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Sample records for moisture sorption isotherm

  1. Mathematical Modeling of Moisture Sorption Isotherms and Determination of Isosteric Heats of Sorption of Ziziphus Leaves

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    Amel Saad

    2014-01-01

    Full Text Available Desorption and adsorption equilibrium moisture isotherms of Ziziphus spina-christi leaves were determined using the gravimetric-static method at 30, 40, and 50°C for water activity (aw ranging from 0.057 to 0.898. At a given aw, the results show that the moisture content decreases with increasing temperature. A hysteresis effect was observed. The experimental data of sorption were fitted by eight models (GAB, BET, Henderson-Thompson, modified-Chung Pfost, Halsey, Oswin, Peleg, and Adam and Shove. After evaluating the models according to several criteria, the Peleg and Oswin models were found to be the most suitable for describing the sorption curves. The net isosteric heats of desorption and adsorption of Ziziphus spina-christi leaves were calculated by applying the Clausius-Clapeyron equation to the sorption isotherms and an expression for predicting these thermodynamic properties was given.

  2. Moisture sorption isotherms of castor beans. Part 2: Thermodynamic properties

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    André L. D. Goneli

    Full Text Available ABSTRACT Knowledge on the water sorption within agricultural products is extremely important for decision making during post-harvest procedures. In order to improve this knowledge, thermodynamic properties regarding water sorption provide useful data. Thermodynamic properties of castor beans, related to sorption, were determined. Static gravimetric technique under different conditions of temperature (25, 35, 45 and 55 ± 1 °C was used. Saturated salt solutions in the range of 37-87% ± 2% were utilized to create the required controlled humidity environment. After the sorption procedure, differential enthalpy, differential entropy and Gibbs free energy of this process were calculated and decreased with increased values of equilibrium moisture content.

  3. Effect of drying methods on the moisture sorption isotherms and thermodynamic properties of mint leaves.

    Science.gov (United States)

    Dalgıç, Ali Coşkun; Pekmez, Hatice; Belibağlı, Kadir Bülent

    2012-08-01

    Mint leaves were dried by three different types of dryers, namely; tray, freeze and distributed (indirect)-type solar dryer. Sorption isotherms of fresh, solar, tray and freeze dried mint were determined at temperatures of 15 °C, 25 °C and 35 °C over a range of relative humidities (10-90%). The effect of drying method on the water sorption isotherms of dried mint samples was evaluated. Experimental data were used to determine the best models for predicting the moisture sorption content of mint. Among nine sorption models tested, Peleg, GAB, Lewicki and modified Mizrahi equations gave the best fit to experimental data. The sorption data were analyzed for determination of monolayer moisture content, density of sorbed water, number of adsorbed monolayers, percent bound water, and surface area of adsorbance. The experimental data were also used to determine some thermodynamic properties of mint.

  4. Effect of plasticizer on moisture sorption isotherm of sugar palm (Arenga Pinnata) starch film

    Science.gov (United States)

    Jatmiko, Tri Hadi; Poeloengasih, Crescentiana D.; Prasetyo, Dwi Joko; Rosyida, Vita Taufika

    2016-02-01

    The effect of plasticizer type (glycerol, sorbitol) and plasticizer concentrations (30, 35, 40, 45% w/w polymer) on the moisture sorption isotherm characteristics of sugar palm (Arenga pinnata) starch films were investigated. Moisture affinity of sugar palm starch films was influenced by the plasticizer type and plasticizer concentration. The affinity of the glycerol plasticized film is stronger than that of sorbitol plasticized film. Sugar palm starch film with a higher concentration of glycerol absorbs more moisture with higher initial absorption rate than that of with sorbitol. Films with higher plasticizer concentration of glycerol and sorbitol show higher equilibrium moisture contents at the given relative humidity. The moisture sorption isotherm characteristic of sugar palm starch films can be described very well with the semi empirical 4 parameter Peleg's model.

  5. Determination of low levels of amorphous content in inhalation grade lactose by moisture sorption isotherms.

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    Vollenbroek, Jasper; Hebbink, Gerald A; Ziffels, Susanne; Steckel, Hartwig

    2010-08-16

    Alpha-lactose monohydrate is widely used as an excipient in dry powder inhalers, and plays a very important role in the efficiency of the drug delivery. Due to the processing, low levels of amorphous lactose could be present in the blends. Varying amounts could have a strong effect on the efficiency of drug delivery of the powder blends. Therefore, the accurate measurement of low levels of amorphous lactose content is very important. A new method was developed to measure the amorphous content, based on dynamic vapour sorption (DVS). In contrast to the traditional re-crystallization approach of amorphous lactose, the new method is based on moisture sorption isotherms. Moisture sorption isotherms of blends of crystalline alpha-lactose and freeze-dried or spray-dried amorphous lactose were measured. By fitting the data with a Brunauer, Emmett, and Teller (BET) isotherm, a linear correlation was found between measured and actual amorphous content for the whole range of 0.1-100%. Differences between freeze-dried and spray-dried lactose, due to different molecular arrangements, could be removed by a preconditioning the samples at 35% RH prior to the isotherm measurement. It was shown that accurate determination of very low concentrations of amorphous lactose content is possible using moisture sorption isotherm analyses. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  6. Moisture Sorption Isotherms and Properties of Sorbed Water of Neem ( Azadirichta indica A. Juss) Kernels

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    Ngono Mbarga, M. C.; Bup Nde, D.; Mohagir, A.; Kapseu, C.; Elambo Nkeng, G.

    2017-01-01

    A neem tree growing abundantly in India as well as in some regions of Asia and Africa gives fruits whose kernels have about 40-50% oil. This oil has high therapeutic and cosmetic qualities and is recently projected to be an important raw material for the production of biodiesel. Its seed is harvested at high moisture contents, which leads tohigh post-harvest losses. In the paper, the sorption isotherms are determined by the static gravimetric method at 40, 50, and 60°C to establish a database useful in defining drying and storage conditions of neem kernels. Five different equations are validated for modeling the sorption isotherms of neem kernels. The properties of sorbed water, such as the monolayer moisture content, surface area of adsorbent, number of adsorbed monolayers, and the percent of bound water are also defined. The critical moisture content necessary for the safe storage of dried neem kernels is shown to range from 5 to 10% dry basis, which can be obtained at a relative humidity less than 65%. The isosteric heats of sorption at 5% moisture content are 7.40 and 22.5 kJ/kg for the adsorption and desorption processes, respectively. This work is the first, to the best of our knowledge, to give the important parameters necessary for drying and storage of neem kernels, a potential raw material for the production of oil to be used in pharmaceutics, cosmetics, and biodiesel manufacturing.

  7. Determination of the Moisture-Sorption Isotherms and Isosteric Heat of Henna Leaves

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    Bennaceur, S.; Draoui, B.; Touati, B.; Benseddik, A.; Saad, A.; Bennamoun, L.

    2015-01-01

    Equilibrium moisture desorption and adsorption isotherms of Lawsonia inermis L. (commonly known as henna) leaves at temperatures of 30, 40 and 50°C with a water activity ranging from 0.057 to 0.898 were obtained by the gravimetric-static method. It was established that when the temperature of these leaves increases, their moisture content increases too with a hysteresis effect. The experimental data on the sorption of the indicated leaves were compared with the corresponding calculation data obtained with the use of the GAB, modified BET, Henderson-Thompson, modified Halsey, modified Oswin, and Peleg models. Evaluation of these models on the basis of statistical processing of the data obtained with them, including the calculus of the standard error and the correlation coefficient, has shown that the GAB and Peleg models represent sorption curves more adequately. The net isosteric heats of desorption and adsorption of henna leaves were determined by the sorption isotherms constructed using the Clausius-Clapeyron equation. An expression for predicting these thermodynamic properties of plants is proposed.

  8. Moisture Sorption Isotherms of Broccoli Interpreted with the Flory-Huggins Free Volume Theory

    NARCIS (Netherlands)

    Jin, X.; Sman, R.G.M. van der; Maanen, J.F.C. van; Deventer, H.C. van; Straten, G. van; Boom, R.M.; Boxtel, A.J.B. van

    2014-01-01

    In this work, the Flory Huggins Free Volume theory is used to interpret the sorption isotherms of broccoli from its composition and using physical properties of the components. This theory considers the mixing properties of water, biopolymers and solutes and has the potential to describe the sorptio

  9. Moisture sorption isotherms and thermodynamic properties of mexican mennonite-style cheese.

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    Martinez-Monteagudo, Sergio I; Salais-Fierro, Fabiola

    2014-10-01

    Moisture adsorption isotherms of fresh and ripened Mexican Mennonite-style cheese were investigated using the static gravimetric method at 4, 8, and 12 °C in a water activity range (aw) of 0.08-0.96. These isotherms were modeled using GAB, BET, Oswin and Halsey equations through weighed non-linear regression. All isotherms were sigmoid in shape, showing a type II BET isotherm, and the data were best described by GAB model. GAB model coefficients revealed that water adsorption by cheese matrix is a multilayer process characterized by molecules that are strongly bound in the monolayer and molecules that are slightly structured in a multilayer. Using the GAB model, it was possible to estimate thermodynamic functions (net isosteric heat, differential entropy, integral enthalpy and entropy, and enthalpy-entropy compensation) as function of moisture content. For both samples, the isosteric heat and differential entropy decreased with moisture content in exponential fashion. The integral enthalpy gradually decreased with increasing moisture content after reached a maximum value, while the integral entropy decreased with increasing moisture content after reached a minimum value. A linear compensation was found between integral enthalpy and entropy suggesting enthalpy controlled adsorption. Determination of moisture content and aw relationship yields to important information of controlling the ripening, drying and storage operations as well as understanding of the water state within a cheese matrix.

  10. Moisture sorption isotherms and thermodynamic properties of Oak wood ( Quercus robur and Quercus canariensis): optimization of the processing parameters

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    Bahar, Rim; Azzouz, Soufien; Remond, Romain; Ouertani, Sahbi; Elaieb, Mohamed Taher; El Cafci, Mohamed Afif

    2017-05-01

    The aim of this paper was to determine the moisture desorption isotherms and essentials thermodynamic properties of two Oak wood varieties. Desorption isotherms were measured using a static gravimetric method at 50, 60, 70 and 80 °C within the range of 5-90 % relative humidity. The equilibrium moisture content decreased with increasing temperature and decreased with decreasing relative humidity at a constant temperature. The `Thermodynamic' sorption equation was found to be the best for describing the experimental moisture sorption isotherms of woods within the range of temperature and water activity investigated. The Fiber saturation point, deduced from the `Thermodynamic' model parameters, depends on the temperature and varying from 22.6 to 54.4 (% kg water/kg dry matter). Isosteric heat of desorption and differential entropy were calculated by applying Clausius-Clapeyron equation to the desorption data fitted by the `Thermodynamic' model. The isosteric heat of desorption and the differential entropy decreased with increasing moisture content according to an exponential law equation and varying from 2.03 to 31.14 kJ/mol and from 73.98 to 4.34 J/(mol K), respectively. The linear relationship between differential enthalpy and entropy satisfied the enthalpy-entropy compensation theory. The sign of Gibbs free energy was found to be positive (+283 J/mol) and (+97 J/mol) for Quercus robur and Quercus canariensis, respectively. The isokinetic temperature was found to be greater than the harmonic temperature. Based on the enthalpy-entropy compensation theory, it could be concluded that the moisture desorption isotherm of Oak wood is a non-spontaneous and enthalpy-controlled process.

  11. Moisture sorption isotherms and thermodynamic properties of Oak wood (Quercus robur and Quercus canariensis): optimization of the processing parameters

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    Bahar, Rim; Azzouz, Soufien; Remond, Romain; Ouertani, Sahbi; Elaieb, Mohamed Taher; El Cafci, Mohamed Afif

    2016-09-01

    The aim of this paper was to determine the moisture desorption isotherms and essentials thermodynamic properties of two Oak wood varieties. Desorption isotherms were measured using a static gravimetric method at 50, 60, 70 and 80 °C within the range of 5-90 % relative humidity. The equilibrium moisture content decreased with increasing temperature and decreased with decreasing relative humidity at a constant temperature. The `Thermodynamic' sorption equation was found to be the best for describing the experimental moisture sorption isotherms of woods within the range of temperature and water activity investigated. The Fiber saturation point, deduced from the `Thermodynamic' model parameters, depends on the temperature and varying from 22.6 to 54.4 (% kg water/kg dry matter). Isosteric heat of desorption and differential entropy were calculated by applying Clausius-Clapeyron equation to the desorption data fitted by the `Thermodynamic' model. The isosteric heat of desorption and the differential entropy decreased with increasing moisture content according to an exponential law equation and varying from 2.03 to 31.14 kJ/mol and from 73.98 to 4.34 J/(mol K), respectively. The linear relationship between differential enthalpy and entropy satisfied the enthalpy-entropy compensation theory. The sign of Gibbs free energy was found to be positive (+283 J/mol) and (+97 J/mol) for Quercus robur and Quercus canariensis, respectively. The isokinetic temperature was found to be greater than the harmonic temperature. Based on the enthalpy-entropy compensation theory, it could be concluded that the moisture desorption isotherm of Oak wood is a non-spontaneous and enthalpy-controlled process.

  12. PENGARUH ISOTERM SORPSI AIR TERHADAP STABILITAS BERAS UBI [Effect of Moisture Sorption Isotherm to Stability of “Sweet Potato Rice”

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    Sri Widowati1*

    2010-12-01

    Full Text Available “Sweet Potato Rice” stability as a dry food product was determined by water activity (aw and equilibrium moisture content (Me. This relationship is known as moisture sorption isotherm. This research were aimed 1 to study moisture sorption isotherm of “Sweet Potato Rice” from sweet potato flour (Cangkuang variety and native/heat moisture treatment (HMT starch which was stored at the range of aw:0.06 - 0.96 and 28oC; 2 to determine an appropriate model for describing product moisture sorption isotherm and 3 to predict “Sweet Potato Rice” shelf of life. Experimental design used was a random complete design with two factor, namely: 1 sweet potato starch: native and HMT, and 2 packaging material: polyethylene (PE and polypropylene (PP.The result showed that the moisture sorption isotherm profiles were sigmoid. Smith equation was the best model which described moisture sorption isotherm with R2= 0,991-0,993 for adsorption and R2= 0,964-0,971 for desorption. Shelf life test showed that “Sweet Potato Rice” from Cangkuang flour and modified starch had longer shelf life (5.67 months when packed in PP bag and 2.3 months when packed in PE bag; while shelf life artificial sweet potato made from Cangkuang flour and native starch was 4.24 months when packed in PP bag and 1.72 months when packed in PE bag.

  13. Sorption isotherms and isosteric heats of sorption of Malaysian paddy.

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    Mousa, Wael; Ghazali, Farinazleen Mohamad; Jinap, S; Ghazali, Hasanah Mohd; Radu, Son

    2014-10-01

    Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50 °C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption.

  14. Moisture sorption isotherms and glass transition temperature of elecampe (Inula helenium L.) and burdock (Arctium lappa L.) roots at 25°C.

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    Cervenka, L; Kubínová, J; Juszczak, L; Witczak, M

    2012-02-01

    Sorption isotherms of elecampe (Inula helenium L.) and burdock (Arctium lappa L.) root samples were obtained at 25 °C. Elecampe exhibited hysteresis loop in the range of 0.35-0.90 a(w) , whereas burdock roots showed significant differences between adsorption and desorption isotherms from 0.65 to 0.80 a(w) . Blahovec-Yanniotis was considered to give the best fit over the whole range of a(w) tested. Various parameters describing the properties of sorbed water derived from GAB, Henderson and Blahovec-Yanniotis models have been discussed. Differential scanning calorimetric method was used to measure the glass transition temperature (T (g)) of root samples in relation to water activity. The safe moisture content was determined in 12.01 and 14.96 g/100 g d. b. for burdock and elecampe root samples at 25 °C, respectively. Combining the T (g) line with sorption isotherm in one plot, it was found that the glass transition temperature concept overestimated the temperature stability for both root samples.

  15. Modeling and Prediction of Soil Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per;

    2015-01-01

    Soil water vapor sorption isotherms describe the relationship between water activity (aw) and moisture content along adsorption and desorption paths. The isotherms are important for modeling numerous soil processes and are also used to estimate several soil (specific surface area, clay content......, cation exchange capacity) and engineering properties (e.g., swelling potential). Our objectives for this work were to: (i) evaluate the potential of several theoretical and empirical isotherm models to accurately describe measured moisture adsorption/desorption isotherms (aw range of 0.03 to 0.......93) for a wide range of soils; and (ii) develop and test regression models for estimating the isotherms from clay content. Preliminary results show reasonable fits of the majority of the investigated empirical and theoretical models to the measured data although some models were not capable to fit both sorption...

  16. Exploring the problem of mold growth and the efficacy of various mold inhibitor methods during moisture sorption isotherm measurements.

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    Yu, X; Martin, S E; Schmidt, S J

    2008-03-01

    Mold growth is a common problem during the equilibration of food materials at high relative humidity values using the standard saturated salt slurry method. Exposing samples to toluene vapor and mixing samples with mold inhibitor chemicals are suggested methods for preventing mold growth while obtaining isotherms. However, no published research was found that examined the effect of mold growth on isotherm performance or the efficacy of various mold inhibitor methods, including their possible effect on the physicochemical properties of food materials. Therefore, the objectives of this study were to (1) explore the effect of mold growth on isotherm performance in a range of food materials, (2) investigate the effectiveness of 4 mold inhibitor methods, irradiation, 2 chemical inhibitors (potassium sorbate and sodium acetate), and toluene vapor, on mold growth on dent corn starch inoculated with A. niger, and (3) examine the effect of mold inhibitor methods on the physicochemical properties of dent corn starch, including isotherm performance, pasting properties, gelatinization temperature, and enthalpy. Mold growth was found to affect starch isotherm performance by contributing to weight changes during sample equilibration. Among the 4 mold inhibitor methods tested, irradiation and toluene vapor were found to be the most effective for inhibiting growth of A. niger on dent cornstarch. However, both methods exhibited a significant impact on the starches' physiochemical properties, suggesting the need to probe the efficacy of other mold inhibitor methods and explore the use of new rapid isotherm instruments, which hamper mold growth by significantly decreasing measurement time.

  17. Moisture Sorption in Porous Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    2007-01-01

    Abstract: Information on pore geometry is very important in any study of the mechanical and physical behavior of porous materials. Unfortunately pores are not very accessible for direct measurements. Indirect methods have to be used which involve impregnation (sorption) experiments from which...... in the subject considered this software is available on request to the author. Keywords: Porous materials, moisture, adsorption, desorption, BET-parameters....

  18. Moisture sorption characteristics of microalgae Spirulina platensis

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    E. G. Oliveira

    2009-03-01

    Full Text Available In recent times, the microalgae Spirulina platensis has been used as a functional ingredient in several food applications; its process involving drying and storage steps. Moisture equilibrium data for adsorption isotherms of microalgae Spirulina were investigated at 10, 20 and 30ºC and for desorption, at 40, 50 and 60ºC, using the gravimetric static method. The experimental data were analyzed by GAB and BET models. The GAB equation showed the best fitting to the experimental data with R² ≈ 99% and MRE < 10%. The water surface area values calculated by GAB and BET models were very similar. The isosteric heats were determined by application of Clausius-Clapeyron equation to sorption isotherms obtained from the best-fitting equation. The isosteric heat and the entropy of desorption isotherm presented similar behavior, with a sharp change in an equilibrium moisture content of 10%. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that they are enthalpy-controlled.

  19. ANALISIS FRAKSI-FRAKSI KURVA ISOTERMI SORPSI AIR DARI TEPUNG ROSELA DAN PENGARUHNYA TERHADAP SIFAT-SIFAT MUTU PRODUK [Analysis of Moisture Sorption Isotherm Fraction of Roselle Powder and Its Effect on Products the Quality Characteristics

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    Rita Hayati

    2013-06-01

    Full Text Available The purpose of this study was to determine the fractions of moisture sorption isotherm curve and the critical water content of roselle powder and its effect on the product quality during storage. Roselle flowers were harvested at 25 days after flowering and sun dried (30ºC for 3 days. The result showed that the moisture sorption isotherm curve of the roselle powder was sigmoid. The critical transition points among the three fractions of the bound water in the roselle flour were first at moisture content (Mp and water activity (ap of 7.97% dry basis (db and 0.23 respectively, and second at Ms 21.1% db water content and water activity (as of 0.65%. Roselle powder samples were stored for 20 days at three relative humidity (RH fractions represented by RH 22% (moisture content at 7.2% db, RH 57 % (20.5% db and 84 % (54.2% db. The samples stored in the first fraction was stable in texture, colour and appearance, while the sample in the secondary bound water fraction (21.1% db, changed in colour into darker red. The sample stored in the tertiary bound water fraction (54.2% db changed into brown colour with musty smell and mouldy after 15 days.

  20. An improved experimental and regression methodology for sorption isotherms

    NARCIS (Netherlands)

    Quirijns, E.J.; Boxtel, van A.J.B.; Loon, van W.K.P.; Straten, van G.

    2005-01-01

    Sorption isotherms of corn and starch cylinders with immobilised catalase are experimentally determined at different temperatures for use in drying models in optimal control studies. This application of the sorption isotherm requires an accurate prediction of the sorption data at different temperatu

  1. Moisture sorption characteristics of freeze-dried human platelets

    Institute of Scientific and Technical Information of China (English)

    Meng-jie XU; Guang-ming CHEN; Ju-li FAN; Jin-hui LIU; Xian-guo XU; Shao-zhi ZHANG

    2011-01-01

    Freeze-drying is a promising method for a long-term storage of human platelets. The moisture sorption characteristics of freeze-dried human platelets (FDHPs) were studied in this paper. The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer (FDLB) were measured at 4, 25, and 37 ℃. The experimental data were fitted to Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) equations. There were no significant statistical differences (P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25 ℃, while FDHPs absorbed more water at 37 ℃. The net isosteric heat of sorption was derived. The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37 ℃ data were used. Dynamic sorption experiments were carried out at 25 ℃ with environmental water activity controlled at 0.75, 0.85, and 0.90. The moisture diffusion coefficient was fitted to be 8.24x 10-12 m2/s when experimental data at initial time were used. These results would be helpful in choosing prehydration and storage condition for FDHPs.

  2. Moisture Sorption Characteristics of Corn Stover and Big Bluestem

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    C. Karunanithy

    2013-01-01

    Full Text Available Moisture content is an important feedstock quality in converting it into energy through biochemical or thermochemical platforms. Knowledge of moisture sorption relationship is useful in drying and storage to preserve the quality of feedstocks. Moisture sorption isotherms for potential feedstocks such as corn stover and big bluestem are missing. EMC values of corn stover and big bluestem were determined using static gravimetric technique with saturated salt solutions (ERH 0.12–0.89 at different temperatures (20, 30, and 40°C. Depending upon the ERH values, EMC values were ranged from 8.0 to 19.6 and 8.8 to 19.2% db for corn stover and big bluestem, respectively, and they followed typical type II isotherm found in food materials. Nonlinear regression was used to fit five commonly used three-parameter isotherm models (i.e., modified Oswin model, modified Halsey model, modified Chung-Pfost model, modified Henderson model, and the modified Guggenheim-Anderson-de Boer (GAB model to the experimental data. Modified Halsey emerged as the best model with high F-statistic and R2 values with low Em and Es and fairly random scattered residual plot for corn stover and big bluestem. These models can be used to predict the equilibrium moisture content of these feedstocks starting from harvesting, drying, preprocessing, transportation, storage, and conversion.

  3. Assessment of suitability of some chosen functions for describing of sorption isotherms in building materials

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    Stolarska, Agata; Garbalińska, Halina

    2016-10-01

    This paper presents results of tests and studies conducted on six common building materials, used for constructing and finishing of external walls. These included: ceramic brick, silicate brick, autoclaved aerated concrete, cement mortar, cement-lime mortar and cement mortar modified with polypropylene fibers. Each of these materials is distinguished by the other structure of porousness, affecting both the course of sorption processes and the isotherms obtained. At first, measurements of moisture sorption kinetics at temperatures of 5, 20 and 35 °C were performed, each time at six levels of relative humidity. Then, when the sorption processes expired, equilibrium moisture sorption values were determined for the materials in 18 individual temperature and humidity conditions. The experimental data were used to determine the sorption isotherm courses for each material at the three temperatures. Then, theoretical analysis was performed in order to determine, which of the models available in the literature described the sorption isotherms of the concerned building materials the best. For each material and each of the three temperature values, twenty-four equations were tested. In each case, those of them were identified which ensured the best matching between the theoretical courses and the experimental data. The obtained results indicate that the Chen's model proved to be the most versatile. It ensured a detailed description of the sorption isotherms for each material and temperature tested.

  4. Experience of Implementing Moisture Sorption Control in Historical Archives

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    P. Zítek

    2006-01-01

    Full Text Available This paper deals with a novel approach to inhibiting the harmful impact of moisture sorption in old art works and historical exhibits preserved in remote historic buildings that are in use as depositories or exhibition rooms for cultural heritage collections. It is a sequel to the previous work presented in [2], where the principle of moisture sorption stabilization was explained. Sorption isotherm investigations and EMC control implementation in historical buildings not provided with heating are the main concern in this paper. The proposed microclimate adjustment consists in leaving the interior temperature to run almost its spontaneous yearly cycle, while the air humidity is maintained in a specific relationship to the current interior temperature. The interior air humidity is modestly adjusted to protect historical exhibits and art works from harmful variations in the content of absorbed moisture, which would otherwise arise owing to the interior temperature drifts. Since direct measurements of moisture content are not feasible, the air humidity is controlled via a model-based principle. Two long-term implementations of the proposed microclimate control have already proved that it can permanently maintain a constant moisture content in the preserved exhibits. 

  5. Study of thermodynamic water properties and moisture sorption hysteresis of mango skin

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    Silvio José Ferreira de Souza

    2015-03-01

    Full Text Available The equilibrium moisture content for adsorption and desorption isotherms of mango skin was determined using the static gravimetric method at temperatures of 20, 26, 33, 38 and 44 oC in the 0.056 to 0.873 water activity range. Both sorption curves show a decrease in equilibrium moisture content as the temperature increasing. The hysteresis effect was observed at constant water activity. The Guggenheim, Anderson, and de Boer (GAB model presented the best fitting accuracy among a group of models and was used to determine the thermodynamic properties of water sorption. Integral enthalpy and integral entropy areas showed inverted values for the adsorption and desorption isotherms over the wide range of water activity studied. These values confirm, in energetic terms, the difference between adsorption and desorption isotherms observed in the hysteresis phenomenon. Finally, the Gibbs free energy revealed that the sorption process was spontaneous for both sorption isotherms.

  6. Isotherm, kinetic, and thermodynamic study of ciprofloxacin sorption on sediments.

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    Mutavdžić Pavlović, Dragana; Ćurković, Lidija; Grčić, Ivana; Šimić, Iva; Župan, Josip

    2017-04-01

    In this study, equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The K d parameter from linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin-Radushkevich (D-R) sorption models were applied to describe the equilibrium isotherms by linear and nonlinear methods. The estimated K d values varied from 171 to 37,347 mL/g. The obtained values of E (free energy estimated from D-R isotherm model) were between 3.51 and 8.64 kJ/mol, which indicated a physical nature of ciprofloxacin sorption on studied sediments. According to obtained n values as measure of intensity of sorption estimate from Freundlich isotherm model (from 0.69 to 1.442), ciprofloxacin sorption on sediments can be categorized from poor to moderately difficult sorption characteristics. Kinetics data were best fitted by the pseudo-second-order model (R (2) > 0.999). Thermodynamic parameters including the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to estimate the nature of ciprofloxacin sorption. Results suggested that sorption on sediments was a spontaneous exothermic process.

  7. Sorption isotherms for oat flakes (Avena sativa L.

    Directory of Open Access Journals (Sweden)

    José Edgar Zapata M.

    2014-04-01

    Full Text Available Moisture sorption isotherms of oat flakes were determined at temperatures of 5, 25 and 37°C, using a gravimetric technique in an a w range of between 0.107 and 0.855. These curves were modeled using six equations commonly applied in food. The quality of the fit was assessed with the regression coefficient (r² and the mean relative percentage error (MRPE. The best fit were obtained with the Caurie model with r² of 0.996, 0.901 and 0.870, and MRPE of 7.190, 17.878 and 16.206, at 5, 25 and 37°C, respectively. The equilibrium moisture presented a dependence on temperature in the studied a w range, as did the security moisture (X S. These results suggest that the recommended storage conditions of oat flakes include: a relative air humidity of 50% between 5 and 25°C and of 38% up to 37°C.

  8. Sorption isotherms modeling approach of rice-based instant soup mix stored under controlled temperature and humidity

    Directory of Open Access Journals (Sweden)

    Yogender Singh

    2015-12-01

    Full Text Available Moisture sorption isotherms of rice-based instant soup mix at temperature range 15–45°C and relative humidity from 0.11 to 0.86 were determined using the standard gravimetric static method. The experimental sorption curves were fitted by five equations: Chung-Pfost, GAB, Henderson, Kuhn, and Oswin. The sorption isotherms of soup mix decreased with increasing temperature, exhibited type II behavior according to BET classification. The GAB, Henderson, Kuhn, and Oswin models were found to be the most suitable for describing the sorption curves. The isosteric heat of sorption of water was determined from the equilibrium data at different temperatures. It decreased as moisture content increased and was found to be a polynomial function of moisture content. The study has provided information and data useful in large-scale commercial production of soup and have great importance to combat the problem of protein-energy malnutrition in underdeveloped and developing countries.

  9. Acquisition of sorption isotherms for modified woods by the use of dynamic vapour sorption instrumentation. Principles and Practice

    DEFF Research Database (Denmark)

    Engelund, Emil Tang; Klamer, Morten; Venås, Thomas Mark

    2010-01-01

    The complex wood-water relationship has been the topic of numerous studies. Sorption isotherms – in particular – have been derived for hundreds of wood species, their sap- and heartwood sections as well as for decayed, engineered and modified wood materials. However, the traditional methods...... was quantified by the reduction in moisture content relative to untreated Scots pine sapwood. This may be used in future documentation of the resistance of modified wood to fungal decay....

  10. Modeling polychlorinated biphenyl sorption isotherms for soot and coal

    NARCIS (Netherlands)

    Jantunen, A.P.K.; Koelmans, A.A.; Jonker, M.T.O.

    2010-01-01

    Sorption isotherms (pg-ng/L) were measured for 11 polychlorinated biphenyls (PCBs) of varying molecular planarity from aqueous solution to two carbonaceous geosorbents, anthracite coal and traffic soot. All isotherms were reasonably log-log-linear, but smooth for traffic soot and staircase-shaped

  11. Implementation of sorption hysteresis in multi-Fickian moisture transport

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan

    2007-01-01

    represent this behavior. The multi-Fickian model describes the combined transport of bound water and vapor and their interaction through sorption. The bound-water concentration is also influenced by sorption hysteresis. In the worst case, sorption hysteresis may result in deviations of up to 30......-35% in moisture content. Hence, for a precise moisture content computation, sorption hysteresis must be taken into account. The present paper explains the relation between sorption hysteresis and multi-Fickian moisture transport, and clarifies how models for the two phenomena are coupled. To illustrate...

  12. Implementation of sorption hysteresis in multi-Fickian moisture transport

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan

    2007-01-01

    this behavior. The multi-Fickian model describes the combined transport of bound water and vapor and their interaction through sorption. The bound-water concentration is also influenced by sorption hysteresis. In the worst case, sorption hysteresis may result in deviations of up to 30-35% in moisture content....... Hence, for a precise moisture content computation, sorption hysteresis must be taken into account. The present paper explains the relation between sorption hysteresis and multi-Fickian moisture transport, and clarifies how models for the two phenomena are coupled. To illustrate the effects, a finite...

  13. Sorption Isotherm of Southern Yellow Pine—High Density Polyethylene Composites

    Directory of Open Access Journals (Sweden)

    Feihong Liu

    2015-01-01

    Full Text Available Temperature and relative humidity (RH are two major external factors, which affect equilibrium moisture content (EMC of wood-plastic composites (WPCs. In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP-high density polyethylene (HDPE composites was investigated. All samples were equilibriumed at 20 °C and various RHs including 16%, 33%, 45%, 66%, 75%, 85%, 93%, and100%. EMCs obtained from desorption and absorption for different WPC samples were compared with Nelson’s sorption isotherm model predictions using the same temperature and humidity conditions. The results indicated that the amount of moisture absorbed increased with the increases in RH at 20 °C. All samples showed sorption hysteresis at a fixed RH. Small difference between EMC data of WPC samples containing different amount of ultraviolet (UV stabilizers were observed. Similar results were observed among the samples containing different amount of zinc borate (ZB. The experimental data of EMCs at various RHs fit to the Nelson’s sorption isotherm model well. The Nelson’s model can be used to predicate EMCs of WPCs under different RH environmental conditions.

  14. Determination of storage conditions for new biscuits using their sorption isotherms

    Directory of Open Access Journals (Sweden)

    G. Diukareva

    2015-05-01

    Full Text Available Introduction For the formation of biscuits quality natural carrier of iodine and sweetener from stevia leaves were used. Desorption of moisture is the dominant process, which will determine the guaranteed shelf life of biscuits. The conditions for the developed biscuits storage was determined by investigating of sorption isotherms and kinetics of reaching the equilibrium moisture content. Materials and Methods. The objects of study arenewly developed biscuits: "Health" (rich in iodine and with the replacement of 50 % sugar by stevioside, "Light" (with the replacement of 75% of sugar by stevioside and enriched with wheat bran, "Fortified" (containselamine, which is a natural source of iodine. Control – the biscuit prepared according to traditional recipes. Tenzometric method was used to study the sorption equilibrium moisture content. Differential function of pore radius distribution was determined using sorption isotherms and then have been subjected to approximation. Results. New biscuits samples are in the area of polymolecular and monomolecular sorption in the range of the relative air humidity (RAH from 10 to 75 ... 80%. The control sample has less distinct plot of monomolecular sorption (10 to 20% and short- moisture range wich is corresponding with polymolecularsorption (from 20 to 65 ... 70%. There is a moisture absorbtion ofmicrocapillary and swelling of samples when RAHincreases to 75 ... 80% for all the samples. The ratio of average pore radius tothe most likely of the test samples are differentthat wasshown by the investigation of differential function of pore distribution. So this ratio for biscuit "Health" is 5.73, for biscuit "Light" − 2.98,forbiscuit "Fortified"− 4.91 and for the control − 3.88. Conclusions. There’s the sense to store developed biscuits in a cardboard packaging with polymeric covering, if RAH is not more than 75%, and vapor-proof if RAH is above that.

  15. Modeling polychlorinated biphenyl sorption isotherms for soot and coal

    Energy Technology Data Exchange (ETDEWEB)

    Jantunen, A.P.K.; Koelmans, A.A.; Jonker, M.T.O. [University of Utrecht, Utrecht (Netherlands)

    2010-08-15

    Sorption isotherms (pg-ng/L) were measured for 11 polychlorinated biphenyls (PCBs) of varying molecular planarity from aqueous solution to two carbonaceous geosorbents, anthracite coal and traffic soot. All isotherms were reasonably log-log-linear, but smooth for traffic soot and staircase-shaped for coal, to which sorption was stronger and more nonlinear. The isotherms were modeled using seven sorption models, including Freundlich, (dual) Langmuir, and Polanyi-Dubinin-Manes (PDM). PDM provided the best combination of reliability and mechanistically-interpretable parameters. The PDM normalizing factor Z appeared to correlate negatively with sorbate molecular volume, dependent on the degree of molecular planarity. The modeling results supported the hypothesis that maximum adsorption capacities (Q{sub max}) correlate positively with the sorbent's specific surface area. Q{sub max} did not decrease with increasing sorbate molecular size, and adsorption affinities clearly differed between the sorbents. Sorption was consistently stronger but not less linear for planar than for nonplanar PCBs, suggesting surface rather than pore sorption.

  16. Rapid and fully automated Measurement of Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per

    2014-01-01

    Eminent environmental challenges such as remediation of contaminated sites, the establishment and maintenance of nuclear waste repositories, or the design of surface landfill covers all require accurate quantification of the soil water characteristic at low water contents. Furthermore, several...... essential but difficult-to-measure soil properties such as clay content and specific surface area are intimately related to water vapor sorption. Until recently, it was a major challenge to accurately measure detailed water vapor sorption isotherms within an acceptable time frame. This priority...... and pesticide volatilization, toxic organic vapor sorption kinetics, and soil water repellency are illustrated. Several methods to quantify hysteresis effects and to derive soil clay content and specific surface area from VSA-measured isotherms are presented. Besides above mentioned applications, potential...

  17. MOISTURE SORPTION IN ARTIFICIALLY AGED WOOD-PLASTIC COMPOSITES

    Directory of Open Access Journals (Sweden)

    B. Kristoffer Segerholm,

    2012-01-01

    Full Text Available Moisture sorption in wood-plastic composites (WPCs affects their durability and dimensional stability. In certain outdoor exposures, the moisture properties of WPCs are altered due to e.g. cracks induced by swelling and shrinkage of the components, as well as UV degradation or biological attack. The aim of this work was to study the effect of different artificial ageing routes on the moisture sorption properties of WPCs. Extruded WPCs were prepared with either unmodified or acetylated wood and recycled high-density polyethylene (HDPE. The WPC samples were artificially aged involving water soaking, artificial weathering, and white- or brown-rot decay in different combinations. After the ageing, the samples were conditioned in either 65% or 90% relative humidity (RH until equilibrium moisture content was reached. A dynamic moisture sorption analyzer was used to monitor the sorption rate of samples subjected to a climate change from 65% to 90% RH. Scanning electron microscopy was used to study the surface morphology of the aged composites. Results showed that the artificial weathering caused cracking of the HDPE matrix at the composite surface, as well as a wood-matrix debonding, resulting in an increased moisture sorption rate. The WPC samples subjected to white-rot decay showed the highest moisture sorption rate.

  18. Hysteresis and Temperature Dependency of Moisture Sorption – New Measurements

    DEFF Research Database (Denmark)

    Rode, Carsten; Hansen, Kurt Kielsgaard

    2011-01-01

    It is well known that sorption characteristics of building materials exhibit hysteresis in the way the equilibrium curves develop between adsorption and desorption, and that the sorption curves are also somewhat temperature dependent. However, these two facts are most often neglected in models...... measurements of hysteresis and temperature dependency of the moisture sorption characteristics of three different porous building materials: aerated concrete, cement paste and spruce. Scanning curves are measured for all three materials where periods with adsorption and desorption interrupt each other...

  19. Peculiarities of sorption isotherm and sorption chemisms of caesium by mixed nickel-potassium ferrocyanide based on hydrated titanium dioxide

    OpenAIRE

    Voronina, A. V.; Semenishchev, V. S.; Nogovitsyna, E. V.; Betenekov, N. D.

    2013-01-01

    Sorption isotherm of caesium from tap water by mixed nickel-potassium ferrocyanide based on hydrated titanium dioxide is obtained for a wide range of concentrations of caesium. It is shown that there are three types of specificity to caesium sorption sites in this sorbent. Sorption chemisms of caesium are studied, factors conditioned high sorption capacity of the sorbent are revealed. It is shown that occupation of sorption sites I and II is well approximated by Langmuir equilibrium and this ...

  20. Moisture ingress into electronics enclosures under isothermal conditions

    DEFF Research Database (Denmark)

    Staliulionis, Zygimantas; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based...

  1. Soil-adjusted sorption isotherms for arsenic(V) and vanadium(V)

    Science.gov (United States)

    Rückamp, Daniel; Utermann, Jens; Florian Stange, Claus

    2017-04-01

    The sorption characteristic of a soil is usually determined by fitting a sorption isotherm model to laboratory data. However, such sorption isotherms are only valid for the studied soil and cannot be transferred to other soils. For this reason, a soil-adjusted sorption isotherm can be calculated by using the data of several soils. Such soil-adjusted sorption isotherms exist for cationic heavy metals, but are lacking for heavy metal oxyanions. Hence, the aim of this study is to establish soil-adjusted sorption isotherms for the oxyanions arsenate (arsenic(V)) and vanadate (vanadium(V)). For the laboratory experiment, 119 soils (samples from top- and subsoils) typical for Germany were chosen. The batch experiments were conducted with six concentrations of arsenic(V) and vanadium(V), respectively. By using the laboratory data, sorption isotherms for each soil were derived. Then, the soil-adjusted sorption isotherms were calculated by non-linear regression of the sorption isotherms with additional soil parameters. The results indicated a correlation between the sorption strength and oxalate-extractable iron, organic carbon, clay, and electrical conductivity for both, arsenic and vanadium. However, organic carbon had a negative regression coefficient. As total organic carbon was correlated with dissolved organic carbon; we attribute this observation to an effect of higher amounts of dissolved organic substances. We conclude that these soil-adjusted sorption isotherms can be used to assess the potential of soils to adsorb arsenic(V) and vanadium(V) without performing time-consuming sorption experiments.

  2. Non-isothermal Moisture Transport Through Insulation Materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2008-01-01

    An experimental investigation was conducted in order to draw some conclusions on the magnitude of moisture transport due to temperature gradient on a range of porous light-weight building materials. A special constructed non-isothermal set-up allowed the creation of a temperature gradient of 10K...... conclusions and therefore the question about existence of the type of transport forms driven by the non-isothermal effects remains open. Rather surprisingly, all the materials, including the almost non-hygroscopic materials (e.g. rock wool) and very hygroscopic materials (e.g. cellulose insulation) showed...... and given humidity gradient over the sample. The resulting moisture ux as well as the hygrothermal states around and within the material were monitored. The hypothesis of relative humidity being a driving force for non-isothermal moisture transport already in the hygroscopic range could not be confirmed...

  3. Investigation of Moisture Sorption, Permeability and Drug Release Behavior of Carrageenan/Poly Vinyl Alcohol Films

    Directory of Open Access Journals (Sweden)

    *S. K. Bajpai

    2014-09-01

    Full Text Available This work describes moisture sorption behavior and water vapor permeability of gluteraldehyde –crosslinked Carrageenen/polyvinyl alcohol (Carr/PVA films. The moisture uptake has been studied under various relative humidity (RH and the data obtained has been interpreted in the terms of various isotherm models such as GAB, Oswin and Halsey models. The moisture permeability through the films has been characterized in the terms of various parameters like water vapor transmission rate (WVTR, permeance (P and Water vapor permeability (WVP. It was found that these parameters are greatly affected by the degree of crosslinking of the films. Finally, the model drug Gentamycin Sulphate was loaded in to the films and its release was monitored kinetically in the physiological buffer (PF at 370C. The films exhibited diffusion controlled release mechanism.

  4. Moisture ingress into electronics enclosures under isothermal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Staliulionis, Ž.; Jabbari, M.; Hattel, J. H. [Process Modelling Group, Department of Mechanical engineering, Technical university of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby (Denmark)

    2016-06-08

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based on a 1D quasi-steady state (QSS) approximation for Fick’s second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared to an analytical solution and very good agreement is found.

  5. Moisture ingress into electronics enclosures under isothermal conditions

    DEFF Research Database (Denmark)

    Staliulionis, Zygimantas; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture...... loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based...... on a 1D quasi-steady state (QSS) approximation for Fick's second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared...

  6. [Sorption isotherms and sorption thermodynamics of faecal sterols on offshore sediment].

    Science.gov (United States)

    Zhang, Xiao-Lei; Xue, Wen-Ping; Xu, Heng-Zhen; Ma, Xin-Dong

    2012-10-01

    Experiments of faecal sterols adsorption from aqueous solutions onto Dalian offshore sediment were done by a batch equilibrium method,and the sorption of 12 kinds of faecal sterols in sediment were investigated in this paper. It was shown that the adsorption equilibrium time was 24 h, and after 24 h the variation tendency of 5 kinds of fingerprint values was stable. It indicated that adsorption isothermal data was interpreted by the Henry, Freundlich, Langmuir, Duhinin-Radushkevich(D-R) and Temkin equations, and demonstrated that the other 4 isotherms provided stronger data fitting than the Langumir isotherm. It inferred that from D-R model the mean free energy of adsorption process of 12 kinds of faecal sterols was from 7 071.1 J x mol(-1) to 9 128.7 J x mol(-1), and concluded that it was mainly physical adsorption of the sorptive process of 12 kinds of faecal sterols in sediment. It discovered that from the Temkin model the value of K(f) of cholestanone was the maximum, and extrapolated that cholestanone was adsorbed most easily on sediment. It stated that the enthalpy and entropy change of the adsorption were both less than zero, and inferred that the adsorption process was exothermic and spontaneous.

  7. ISOFIT - A PROGRAM FOR FITTING SORPTION ISOTHERMS TO EXPERIMENTAL DATA

    Science.gov (United States)

    Isotherm expressions are important for describing the partitioning of contaminants in environmental systems. ISOFIT (ISOtherm FItting Tool) is a software program that fits isotherm parameters to experimental data via the minimization of a weighted sum of squared error (WSSE) obje...

  8. Thermodynamic properties of water sorption of jackfruit (Artocarpus heterophyllus Lam. as a function of moisture content

    Directory of Open Access Journals (Sweden)

    Ana Paula Prette

    2013-03-01

    Full Text Available The Jackfruit tree is one of the most significant trees in tropical home gardens and perhaps the most widespread and useful tree in the important genus Artocarpus. The fruit is susceptible to mechanical and biological damage in the mature state, and some people find the aroma of the fruit objectionable, particularly in confined spaces. The dehydration process could be an alternative for the exploitation of this product, and the relationship between moisture content and water activity provides useful information for its processing and storage. The aim of this study was to determine the thermodynamic properties of the water sorption of jackfruit (Artocarpus heterophyllus Lam. as a function of moisture content. Desorption isotherms of the different parts of the jackfruit (pulp, peduncle, mesocarp, peel, and seed were determined at four different temperatures (313.15, 323.15, 333.15, and 343.15 K in a water activity range of 0.02-0.753 using the static gravimetric method. Theoretical and empirical models were used to model the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to calculate the isosteric heat of sorption, the differential entropy, and Gibbs' free energy using the Guggenhein-Anderson-de Boer and Oswin models considering the effect of temperature on the hygroscopic equilibrium.

  9. Model Based Control of Moisture Sorption in a Historical Interior

    Directory of Open Access Journals (Sweden)

    P. Zítek

    2005-01-01

    Full Text Available This paper deals with a novel scheme for microclimate control in historical exhibition rooms, inhibiting moisture sorption phenomena that are inadmissible from the preventive conservation point of view. The impact of air humidity is the most significant harmful exposure for a great deal of the cultural heritage deposited in remote historical buildings. Leaving the interior temperature to run almost its spontaneous yearly cycle, the proposed non-linear model-based control protects exhibits from harmful variations in moisture content by compensating the temperature drifts with an adequate adjustment of the air humidity. Already implemented in a medieval interior since 1999, the proposed microclimate control has proved capable of permanently maintaining constant a desirable moisture content in organic or porous materials in the interior of a building. 

  10. Inter-laboratory comparison II: CO{sub 2} isotherms measured on moisture-equilibrated Argonne premium coals at 55 C and up to 15 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, A.L.; Romanov, V.; Schroeder, K.; White, C.M. [U.S. Department of Energy, National Energy Technology Laboratory, Pittsburgh, PA (United States); Busch, A.; Gensterblum, Y.; Krooss, B.M. [Institute of Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Aachen (Germany); Bustin, R.M.; Chikatamarla, L. [University of British Columbia, Earth and Ocean Sciences, Vancouver (Canada); Day, S.; Duffy, G.J.; Sakurovs, R. [CSIRO Energy Technology, Newcastle, NSW (Australia); Fitzgerald, J.E.; Gasem, K.A.M.; Jing, C.; Mohammed, S.; Robinson, R.L. Jr. [School of Chemical Engineering, Oklahoma State University, Stillwater, OK (United States); Hartman, C.; Pratt, T. [TICORA Geosciences, Inc.19000 West Hwy. 72, Suite 100, Arvada, CO 80007 (United States)

    2007-11-22

    Sorption isotherms, which describe the coal's gas storage capacity, are important for estimating the carbon sequestration potential of coal seams. This study investigated the inter-laboratory reproducibility of carbon dioxide isotherm measurements on moisture-equilibrated Argonne premium coal samples (Pocahontas No. 3, Illinois No. 6, and Beulah Zap). Six independent laboratories provided isotherm data on the three moisture-equilibrated coal samples at 55 C and pressures up to 15 MPa. Agreement among the laboratories was good up to 8 MPa. At the higher pressures, the data among the laboratories diverged significantly for two of the laboratories and coincided reasonably well for four of the laboratories. (author)

  11. Competitive sorption of CO2 and CH4 on coals as a function of maturity and moisture content

    Science.gov (United States)

    Merkel, Alexej; Gensterblum, Yves; Kroos, Bernhard; Littke, Ralf

    2013-04-01

    The competitive sorption of CH4 and CO2 from a two-component gas mixture on coals of different rank and moisture content has been studied at pressures up to 10 MPa. The aim of this study was to assess, the maximum sorption capacity as well as the selectivity of dry and moisturised coals of different rank with respect to sorption of CH4and CO2. The research addresses possible implications on Enhanced Coal Bed Methane (ECBM) recovery projects, where CO2is to be injected into coal seams to increase CH4production rates. The measurements were conducted using a manometric setup with continuous pressure and temperature recording and periodic analysis of gas compositions in the reference cell and the measuring cell throughout the duration of the experiment. Isotherms were determined with a gas mixture containing 70-80% CH4. Three isotherms were measured at three different moisture states for each of the three coal samples of different rank. A significant decrease of total excess sorption capacity was observed with increasing moisture content from the dry sample to the sample moisturised at 53% relative humidity (RH). The initial reduction of sorption capacity decreases with rank. Only a small further decrease occurred from 53% to the 97% RH moisturised coals. The effect of moisture on sorption capacity and selectivity is highly rank-dependent. In all cases the results show a preferential sorption of CO2from a binary CH4/CO2gas mixture at all three moisture states. Sorption capacity increases with rank for all but the dry state and in all cases the sample with the highest maturity shows the highest sorption capacity by far. Selectivity for CO2 decreases with increasing rank of the coal. The results of this study support that from the thermodynamic point of view coals have a tendency to selectively take up CO2under the conditions of ECBM recovery. The selectivity coefficients are important parameters for ECBM modelling and the design of production strategies.

  12. Moisture sorption curves of fruit and nut cereal bar prepared with sugar and sugar substitutes.

    Science.gov (United States)

    Pallavi, Byrappa Vasu; Chetana, Ramakrishna; Ravi, Ramaswamy; Reddy, Sunkireddy Yella

    2015-03-01

    Low sugar, low fat, dry fruit and nut cereal bars without sugar were prepared using cereals, nuts, and sugar substitutes. The sorption characteristics of the bars prepared with sugar substitutes in comparison with that of sugar were studied by keeping the bars at water activity (aw) from 0.1 to 0.9. The sorption isotherms of low sugar bars were practically identical below aw of 0.5 but above aw of 0.5, a clear differentiation in the isotherms could be observed compared to that of sugar counterpart. A sharp increase in moisture content was observed in the bars prepared with alternative sweeteners, above aw 0.6, whereas a gradual increase in aw was observed in the case of bar prepared with sugar. The ERH (Equilibrium relative humidity) value for bar with sugar was 50 %, and for bars prepared with alternative sweeteners, it was about 60 %. Low sugar cereal bar prepared with sorbitol + maltitol (SM) syrup scored higher sensory quality compared to other product prepared with sorbitol + nutriose (SN) as the former retained softness and chewiness on storage. Thus, it was observed that bars with alternative sweeteners will be more stable as their ERH is closer to normal ambient conditions compared to that prepared with sugar.

  13. A study of laboratory testing and calculation methods for coal sorption isotherms

    Institute of Scientific and Technical Information of China (English)

    Lei ZHANG; Ting-Xiang REN; Naj AZIZ

    2013-01-01

    Measurement of the volume of gas adsorbed per unit mass of coal with increasing pressure at a constant temperature produces an isotherm that describes the gas storage capacity of this type of coal.The accurate testing and interpretation of coal sorption isotherm plays an important role in the areas of coal mine methane drainage,coalbed methane (CBM) reservoir resource assessment,enhanced coalbed methane (ECBM) recovery,as well as the carbon dioxide (CO2) sequestration in deep coal seams or similar geological formations.Different coal sorption isotherm testing apparatus and associated calculation methods are critically reviewed and presented in this paper.These include both volumetric and gravimetric based methods,as well as experimental sorption tests with confining stress and direction sorption methods.The volumetric techniques utilise experimental apparatus with sample cell and injection pump and that with both sample cell and reference cell.Whilst the gravimetric approachesinclude methods with sample cell and suspension magnetic balance and that with both sample cell and reference cell.Different testing methods are compared and discussed in this study.A unique in-house-built coal sorption isotherm testing apparatus at the University of Wollongong was presented together with the calculation method,procedures and experimental results.The isotherm results can be calculated by both Soave-Redlich-Kwong (SRK) equation and calibration cure methods which can be used directly to convert the volume of adsorbed gas in different test conditions to standard condition (NTP).

  14. Nitrate sorption on activated carbon modified with CaCl2: Equilibrium, isotherms and kinetics

    Directory of Open Access Journals (Sweden)

    Zanella Odivan

    2015-01-01

    Full Text Available In this study, nitrate (NO3- removal from aqueous solutions was investigated using granular activated carbon (GAC modified with CaCl2. Batch sorption studies were performed as a function of sorbent dose, initial nitrate concentration and pH. Sorption was maximized between pH 3 and 9. Studies on the effect of pH showed that the ion exchange mechanism might be involved in the sorption process. The percentage of nitrate removed increased with increasing sorbent concentration, and the ideal sorbent dose was found to be 20 g•L-1. Four isotherm models-Langmuir, Freundlich, Redlich-Peterson and Sips-were used to fit the experimental data. The Redlich-Peterson isotherm model explained the sorption process well and showed the best coefficient of determination (0.9979 and Chi-square test statistic (0.0079. Using the Sips isotherm model, the sorption capacity (qe was found to be 1.93 mg nitrate per g of sorbent. Kinetic experiments indicated that sorption was a fast process, reaching equilibrium within 120 min. The nitrate sorption kinetic data were successfully fitted to a pseudo-second-order kinetic model. The overall results demonstrated potential applications of modified GAC for nitrate removal from aqueous solutions.

  15. Moisture sorption and thermal characteristics of polyaramide blend fabrics

    OpenAIRE

    Genç, Gözde; Alp, Burcu; Balköse, Devrim; Ülkü, Semra; Cireli, Aysun

    2006-01-01

    Four types of fabrics woven from various polyaramid fibers of Nomex and Kevlar blends were characterized by morphology, XRD, elemental analysis, thermal analysis, and moisture adsorption isotherms. The blends consisted of Polybenzimidazole/ Kevlar blend (40% FBI and 60% Kevlar®), Nomex Delta A (blend of 60% Kevlar and 40% Nomex®), Nomex Delta T (blend of 75% Nomex, 23% Kevlar, and 2% P140 antistatic fiber), and Nomex III (fabric with a 95/5 blend of Nomex and Kevlar) containing 1% steel fiber...

  16. Gas Permeation Related to the Moisture Sorption in Films of Glassy Hydrophilic Polymers

    NARCIS (Netherlands)

    Laksmana, F. L.; Kok, P. J. A. Hartman; Frijlink, H. W.; Vromans, H.; Maarschalk, K. Van Der Voort

    2010-01-01

    The purpose of this article is to elucidate the effect of integral sorption of moisture on gas permeation in glassy hydrophilic polymers. The oxygen and the simultaneous moisture sorption into various hydroxypropyl methylcellulose (HPMC) films were measured under a wide range of relative humidities

  17. Gas Permeation Related to the Moisture Sorption in Films of Glassy Hydrophilic Polymers

    NARCIS (Netherlands)

    Laksmana, F. L.; Kok, P. J. A. Hartman; Frijlink, H. W.; Vromans, H.; Maarschalk, K. Van Der Voort

    2010-01-01

    The purpose of this article is to elucidate the effect of integral sorption of moisture on gas permeation in glassy hydrophilic polymers. The oxygen and the simultaneous moisture sorption into various hydroxypropyl methylcellulose (HPMC) films were measured under a wide range of relative humidities

  18. Parametric Analysis of a Heavy Metal Sorption Isotherm Based on Fractional Calculus

    Directory of Open Access Journals (Sweden)

    Enrico M. Gomes

    2013-01-01

    Full Text Available Heavy metals are widely recognized as being hazardous to human health and environmentally aggressive. The literature reports different approaches for lead removal, for example, water hyacinths. Heavy metal sorption isotherm modeling represents an important tool towards the study of equilibrium conditions. Fractional calculus represents a novel approach and a growing research field for process modeling, based on derivatives of arbitrary order. Recently, a novel isotherm based on fractional calculus was proposed for lead sorption using water hyacinth (Eichhornia crassipes. This paper reports a general procedure on error analysis and its influence on parameter estimation. It was applied to mathematical models based on fractional differential equations, focusing on a heavy metal novel isotherm sorption model. Parameter variance was calculated by using two different approaches (with the complete Hessian matrix and with a simplified Hessian matrix, and joint parameter confidence regions were generated, being successfully able to show that the fractional nature of the model is statistically valid.

  19. Evaluation of theoretical and empirical water vapor sorption isotherm models for soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per;

    2016-01-01

    sorption isotherms of building materials, food, and other industrial products, knowledge about the 24 applicability of these functions for soils is noticeably lacking. We present validation of nine models for characterizing adsorption/desorption isotherms for a water activity range from 0.03 to 0.......93 for 207 soils, widely varying in texture and organic carbon content. In addition the potential applicability of the models for prediction of sorption isotherms from known clay content was investigated. While in general all investigated models described measured adsorption and desorption isotherms...... reasonably well, distinct differences were observed between physical and empirical models and due to the different degrees of freedom of the model equations. There were also considerable differences in model performance for the adsorption and desorption data. Regression analysis relating model parameters...

  20. Equilibrium sorption isotherms for nitrate on resin Amberlite IRA 400.

    Science.gov (United States)

    Chabani, M; Amrane, A; Bensmaili, A

    2009-06-15

    The adsorption isotherms of nitrate on resin Amberlite IRA 400 at various pH, in the range 2-12, were experimentally determined by batch tests. The experimental data have been analysed using the Langmuir, Freundlich, Redlich-Peterson and Sips isotherms models. In order to determine the best fit isotherm, two error analysis methods were used to evaluate the data: the regression correlation coefficient, and the statistic Chi-square test. In the range of pH tested, the Sips model was found to give the best fit of the adsorption isotherm data. The maximum adsorption capacity can be deduced from the obtained correlation coefficients and was found to decrease for increasing pH.

  1. ISOT_Calc: A versatile tool for parameter estimation in sorption isotherms

    Science.gov (United States)

    Beltrán, José L.; Pignatello, Joseph J.; Teixidó, Marc

    2016-09-01

    Geochemists and soil chemists commonly use parametrized sorption data to assess transport and impact of pollutants in the environment. However, this evaluation is often hampered by a lack of detailed sorption data analysis, which implies further non-accurate transport modeling. To this end, we present a novel software tool to precisely analyze and interpret sorption isotherm data. Our developed tool, coded in Visual Basic for Applications (VBA), operates embedded within the Microsoft Excel™ environment. It consists of a user-defined function named ISOT_Calc, followed by a supplementary optimization Excel macro (Ref_GN_LM). The ISOT_Calc function estimates the solute equilibrium concentration in the aqueous and solid phases (Ce and q, respectively). Hence, it represents a very flexible way in the optimization of the sorption isotherm parameters, as it can be carried out over the residuals of q, Ce, or both simultaneously (i.e., orthogonal distance regression). The developed function includes the most usual sorption isotherm models, as predefined equations, as well as the possibility to easily introduce custom-defined ones. Regarding the Ref_GN_LM macro, it allows the parameter optimization by using a Levenberg-Marquardt modified Gauss-Newton iterative procedure. In order to evaluate the performance of the presented tool, both function and optimization macro have been applied to different sorption data examples described in the literature. Results showed that the optimization of the isotherm parameters was successfully achieved in all cases, indicating the robustness and reliability of the developed tool. Thus, the presented software tool, available to researchers and students for free, has proven to be a user-friendly and an interesting alternative to conventional fitting tools used in sorption data analysis.

  2. Moisture Sorption Behaviour and Mould Ecology of Trade Garri Sold in South Eastern Nigeria

    Directory of Open Access Journals (Sweden)

    Tochukwu Samuel

    2014-01-01

    Full Text Available Garri is a creamy white or yellow starchy grit produced by roasting to gelatinization and dryness of peeled, washed, mashed, and fermented dewatered cassava roots. It is the most important product of cassava in West and Central Africa. Mean moisture content of yellow and white garri was 11.11% and 10.81% within 24 hrs of sampling from the market, increasing to 17.27% and 16.14%, respectively, following 3 months of storage at room temperature. The water activity of samples varied from initial 0.587 to 0.934 following storage. Moisture sorption isotherms, determined by static gravimetric techniques at 20° and 30°C, showed temperature dependent BET Sigmoidal type II behaviour typical of carbohydrate rich foods but modulated very slightly by the content of palm oil. Equilibrium moisture content decreased with increase in temperature at constant water activity. A total of 10 fungal species belonging to the genera Mucor, Penicillium, Cephalosporium, Aspergillus, Scopulariopsis, Rhizopus, and Paecilomyces were identified, with range increasing with water activity of samples.

  3. Sorption of Pb2+ from Aqueous Solution unto Modified Rice Husk: Isotherms Studies

    Directory of Open Access Journals (Sweden)

    A. O. Dada

    2013-01-01

    Full Text Available Investigation of the sorption potential of rice husk, an agricultural waste, as an adsorbent was carried out. The rice husk was modified with orthophosphoric acid and was used for adsorption of lead (II ions (Pb2+ from aqueous solution. Physicochemical properties of the modified rice husk were determined. Equilibrium sorption data were confirmed with Langmuir, Freundlich and Temkin adsorption isotherms. On the basis of adsorption isotherm graphs, R2 values were determined to be 0.995, 0.916, and 0.797 for Langmuir, Temkin, and Freundlich isotherms, respectively, indicating that the data fitted well into the adsorption isotherms, but Langmuir isotherm is a better model. The maximum monolayer coverage from Langmuir studies, Qmax=138.89 mg/g, Langmuir isotherm constant, KL=0.699 L/mg, and the separation factor, RL=1.41×10−2 at 100 mg/L of lead(II ions indicating that the sorption process, was favourable. The suitability of modified rice husk as an adsorbent for the removal of lead ions from aqueous solution and its potential for pollution control is established.

  4. Studies of Dye Sensitisation Kinetics and Sorption Isotherms of Direct Red 23 on Titania

    Directory of Open Access Journals (Sweden)

    Peter J. Holliman

    2008-01-01

    Full Text Available Sorption kinetics and isotherms have been measured for a commercial dye (Direct Red 23 on different samples of powdered Titania, and the data were analysed to better understand the dye sensitization process for dye sensitised solar cells (DSSCs. For the sorption kinetics, the data show rapid initial sorption (<1 hour followed by slower rate of increasing uptake between 1 and 24 hours. While higher initial concentrations of dye correspond to higher sorption overall, less dye is absorbed from higher initial dye concentrations when considered as percentage uptake. The correlation between the sorption data and model isotherms has been considered with time. The Langmuir model shows better correlations compared to the Freundlich isotherm. The dye uptake data has also been correlated with Titania characterization data (X-ray diffraction, scanning electron microscopy, BET and zero point charge analysis. Kinetic data show significantly better fits to second-order models compared to first order. This suggests that chemisorption is taking place and that the interaction between the dye sorbate and the Titania sorbent involves electron sharing to form an ester bond.

  5. Methods for determining the CO2 sorption capacity of coal: Experimental and theoretical high pressure isotherms

    Science.gov (United States)

    Weishauptová, Zuzana; Přibyl, Oldřich

    2016-04-01

    One way to reduce CO2 emissions discharged into the atmosphere is by trapping it and storing it in suitable repositories, including coal-bearing strata. The history of coal mining in the Czech Republic is very rich but most of the mines have been closed down in recent years. However, the unmined coal seams are interesting for the purposes of CO2 storage, especially due the opportunities they offer for recovering coal-bed methane. Mine structures of this kind can be found in large parts of the Upper Silesian Basin, where the total storage capacity has been estimated at about 380 Mt CO2. This is an interesting storage potential. In order to identify a suitable high-capacity locality for CO2 storage within a coal seam, it is necessary to study not only the geological conditions within the seam, but also the textural properties of the coal, which control the mechanism and the extent of the storage. The major storage mechanism is by sorption processes that take place in the coal porous system (adsorption in micropores and on the surface of meso/macropores, and absorption in the macromolecular structure). The CO2 sorption capacity is generally indirectly determined in a laboratory by measuring the amount of carbon dioxide captured in a coal sample at a pressure and temperature corresponding to the in situ conditions, using high pressure sorption techniques. The low pressure sorption technique can be used, by setting the partial volumes of CO2 according to its binding and storage mode. The sorption capacity is determined by extrapolation to the saturation pressure as the sum of the individual partially sorbed volumes. The aim of the study was to determine the partial volumes of CO2 bound by different mechanisms in the individual parts of the porous system of the coal, and to compare the sum with the results obtained by the high pressure isotherm. The study was carried out with 3 samples from a borehole survey in the Czech part of the Upper Silesian Basin. A high pressure

  6. Effective moisture diffusivity, moisture sorption, thermo-physical properties and infrared drying kinetics of germinated paddy

    Directory of Open Access Journals (Sweden)

    Supawan Tirawanichakul

    2014-02-01

    Full Text Available Temperature and relative humidity (RH dependence of moisture sorption phenomena for agricultural products provide valuable information related to the thermodynamics of the system. So the equilibrium moisture contents (EMC, effective moisture diffusivity (Deff and thermo-physical properties in terms of void fraction, specific heat capacity, and the apparent density of germinated non-waxy Suphanburi 1 paddy were evaluated. Five commonly cited EMC equations were fitted to the experimental data among temperatures of 40-60°C correlating with RH of 0-90%. The results showed that the modified GAB equation was the best function for describing experimental results while those evaluated thermo-physical properties depended on moisture content. To determine drying kinetics model, the simulated values using Midilli et al. (2002 model and Page’s model was the best fitting to exact drying kinetics values for infrared (IR and hot air (HA drying, respectively. Finally, the Deff value of paddy dried with IR and HA sources were also evaluated and the calculated Deff value of both HA and IR drying was in order of 10-9 m2/s.

  7. Impact of Sequential Ammonia Fiber Expansion (AFEX) Pretreatment and Pelletization on the Moisture Sorption Properties of Corn Stover

    Energy Technology Data Exchange (ETDEWEB)

    Bonner, Ian J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, David N. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Teymouri, Farzaneh [Michigan Biotechnology Inst., Lansing, MI (United States); Campbell, Timothy [Michigan Biotechnology Inst., Lansing, MI (United States); Bals, Bryan [Michigan Biotechnology Inst., Lansing, MI (United States); Tumuluru, Jaya Shankar [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-05-01

    Combining ammonia fiber expansion (AFEX™) pretreatment with a depot processing facility is a promising option for delivering high-value densified biomass to the emerging bioenergy industry. However, because the pretreatment process results in a high moisture material unsuitable for pelleting or storage (40% wet basis), the biomass must be immediately dried. If AFEX pretreatment results in a material that is difficult to dry, the economics of this already costly operation would be at risk. This work tests the nature of moisture sorption isotherms and thin-layer drying behavior of corn (Zea mays L.) stover at 20°C to 60°C before and after sequential AFEX pretreatment and pelletization to determine whether any negative impacts to material drying or storage may result from the AFEX process. The equilibrium moisture content to equilibrium relative humidity relationship for each of the materials was determined using dynamic vapor sorption isotherms and modeled with modified Chung-Pfost, modified Halsey, and modified Henderson temperature-dependent models as well as the Double Log Polynomial (DLP), Peleg, and Guggenheim Anderson de Boer (GAB) temperature-independent models. Drying kinetics were quantified under thin-layer laboratory testing and modeled using the Modified Page's equation. Water activity isotherms for non-pelleted biomass were best modeled with the Peleg temperature-independent equation while isotherms for the pelleted biomass were best modeled with the Double Log Polynomial equation. Thin-layer drying results were accurately modeled with the Modified Page's equation. The results of this work indicate that AFEX pretreatment results in drying properties more favorable than or equal to that of raw corn stover, and pellets of superior physical stability in storage.

  8. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    for estimating clay content from hygroscopic water at different relative humidity (RH) levels while considering hysteresis and organic matter content. Continuous adsorption/desorption vapour sorption isotherm loops were measured for 150 differently textured soils with a state-of-the-art vapour sorption analyser......Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... vapour sorption, which can be measured within a shorter period of time, have recently been developed. Such models are often based on single-point measurements of water adsorption and do not account for sorption hysteresis or organic matter content. The present study introduces regression relationships...

  9. Isothermal titration calorimetry of sorption processes. A promising approach

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Norbert; Foerstendorf, Harald [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Drobot, B. [Technische Univ. Dresden (Germany); Fahmy, Karim [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Biophysics; Reder, Christian

    2017-06-01

    As a consequence of nuclear waste disintegration heat, elevated temperatures in the near field may influence radionuclide retention significantly. However, there is a nearly complete lack of spectroscopic investigations of sorption processes at elevated temperatures. In addition, experimental data on free Gibbs energy (Δ{sub R}G), enthalpy (Δ{sub R}H) and entropy (Δ{sub R}S) of reactions of most radionuclides including fission products such as {sup 79}Se are sparse. Using the Se(IV)/hematite system, we show that microcalorimetry can provide these thermodynamic parameters with high accuracy and in a manner that allows studying various radionuclides.

  10. Adsorption-desorption isotherms and heat of sorption of prickly pear fruit (Opuntia ficus indica)

    Energy Technology Data Exchange (ETDEWEB)

    Lahsasni, S.; Kouhila, M. E-mail: kouhila@hotmail.com; Mahrouz, M

    2004-01-01

    The equilibrium moisture contents were determined for prickly pear fruit using the gravimetric static method at t=30, 40 and 50 deg. C over a range of relative humidities from 0.05 to 0.9. The sorption curves of prickly pear fruit decreased with increase in temperature at constant relative humidity. The hysteresis effect was observed. The GAB, modified Halsey, modified Chung-Pfost, modified Oswin and modified Henderson models were tested to fit the experimental data. The GAB model was found to be the most suitable for describing the sorption curves. The monolayer moisture content values for the sorption at different temperatures are calculated using a modified BET equation. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures.

  11. Optimization of isotherm models for pesticide sorption on biopolymer-nanoclay composite by error analysis.

    Science.gov (United States)

    Narayanan, Neethu; Gupta, Suman; Gajbhiye, V T; Manjaiah, K M

    2017-04-01

    A carboxy methyl cellulose-nano organoclay (nano montmorillonite modified with 35-45 wt % dimethyl dialkyl (C14-C18) amine (DMDA)) composite was prepared by solution intercalation method. The prepared composite was characterized by infrared spectroscopy (FTIR), X-Ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM). The composite was utilized for its pesticide sorption efficiency for atrazine, imidacloprid and thiamethoxam. The sorption data was fitted into Langmuir and Freundlich isotherms using linear and non linear methods. The linear regression method suggested best fitting of sorption data into Type II Langmuir and Freundlich isotherms. In order to avoid the bias resulting from linearization, seven different error parameters were also analyzed by non linear regression method. The non linear error analysis suggested that the sorption data fitted well into Langmuir model rather than in Freundlich model. The maximum sorption capacity, Q0 (μg/g) was given by imidacloprid (2000) followed by thiamethoxam (1667) and atrazine (1429). The study suggests that the degree of determination of linear regression alone cannot be used for comparing the best fitting of Langmuir and Freundlich models and non-linear error analysis needs to be done to avoid inaccurate results.

  12. Parameterizing sorption isotherms using a hybrid global-local fitting procedure

    Science.gov (United States)

    Matott, L. Shawn; Singh, Anshuman; Rabideau, Alan J.

    2017-05-01

    Predictive modeling of the transport and remediation of groundwater contaminants requires an accurate description of the sorption process, which is usually provided by fitting an isotherm model to site-specific laboratory data. Commonly used calibration procedures, listed in order of increasing sophistication, include: trial-and-error, linearization, non-linear regression, global search, and hybrid global-local search. Given the considerable variability in fitting procedures applied in published isotherm studies, we investigated the importance of algorithm selection through a series of numerical experiments involving 13 previously published sorption datasets. These datasets, considered representative of state-of-the-art for isotherm experiments, had been previously analyzed using trial-and-error, linearization, or non-linear regression methods. The isotherm expressions were re-fit using a 3-stage hybrid global-local search procedure (i.e. global search using particle swarm optimization followed by Powell's derivative free local search method and Gauss-Marquardt-Levenberg non-linear regression). The re-fitted expressions were then compared to previously published fits in terms of the optimized weighted sum of squared residuals (WSSR) fitness function, the final estimated parameters, and the influence on contaminant transport predictions - where easily computed concentration-dependent contaminant retardation factors served as a surrogate measure of likely transport behavior. Results suggest that many of the previously published calibrated isotherm parameter sets were local minima. In some cases, the updated hybrid global-local search yielded order-of-magnitude reductions in the fitness function. In particular, of the candidate isotherms, the Polanyi-type models were most likely to benefit from the use of the hybrid fitting procedure. In some cases, improvements in fitness function were associated with slight ( 50%) changes in parameter values were noted. Despite

  13. A study of the water vapor sorption isotherms of hardened cement pastes: Possible pore structure changes at low relative humidity and the impact of temperature on isotherms

    DEFF Research Database (Denmark)

    Wu, Min; Johannesson, Björn; Geiker, Mette Rica

    2014-01-01

    Using water vapor sorption isotherms measured by the “dynamic vapor sorption” (DVS) method, a resaturation study was conducted to investigate possible pore structure changes of hardened cement paste samples caused by the drying at low relative humidity during desorption measurements. The results...... indicate that either the relatively short term drying does not cause any microstructure changes or the pore structure of the hardened cement paste samples can be restored during the absorption process. Additionally, the temperature dependency of sorption isotherms was investigated using both hardened...... cement paste samples and a model material MCM-41. The pronounced impact of temperature on desorption isotherms of cement based materials as reported in literature was not found in this investigation. The results suggest that the differences between the sorption isotherms measured at different...

  14. THE EFFECT OF MOISTURE SORPTION ON THE STRENGTH AND INTERNAL SURFACE-AREA OF LACTOSE TABLETS

    NARCIS (Netherlands)

    RIEPMA, KA; DEKKER, BG; LERK, CF

    1992-01-01

    Tablets compacted from alpha-lactose monohydrate and from roller dried beta-lactose both show time-dependent moisture uptake when exposed to an ambient humid atmosphere. Moisture sorption tends to reach a plateau within 10 min and is accompanied by a decrease in both crushing strength and specific

  15. THE EFFECT OF MOISTURE SORPTION ON THE STRENGTH AND INTERNAL SURFACE-AREA OF LACTOSE TABLETS

    NARCIS (Netherlands)

    RIEPMA, KA; DEKKER, BG; LERK, CF

    1992-01-01

    Tablets compacted from alpha-lactose monohydrate and from roller dried beta-lactose both show time-dependent moisture uptake when exposed to an ambient humid atmosphere. Moisture sorption tends to reach a plateau within 10 min and is accompanied by a decrease in both crushing strength and specific B

  16. Sorption isotherms of brominated diphenyl ethers on natural soils with different organic carbon fractions

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wenxin, E-mail: wxliu@urban.pku.edu.cn [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Li Weibo [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Xing Baoshan [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States); Chen Jianglin [North China Sea Standard and Metrology Center of State Oceanic Administration (SOA), Qingdao 266033 (China); Tao Shu [Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

    2011-10-15

    Sorption isotherms of BDE-28 and BDE-47 on natural soils with different contents of soil organic matter (SOM) were investigated. Due to low water solubility of BDEs and resulted narrow ranges of aqueous equilibrium concentration, the linear distribution model showed similar and good fitting efficiency to the linear portion of nonlinear Freundlich curve. For the same sample, the linear and nonlinear model fitting sorption coefficients were close. At the statistically significant level of 0.05 or 0.1, significant relationships of total organic carbon fraction (fOC) with the fitting sorption coefficients can be observed. As for BDE-28, the relationships of fOC and SOM fractions with the single point partition coefficients at different aqueous concentrations of BDEs were significant; while for BDE-47, the relationships became less significant or insignificant, especially at higher aqueous concentrations. The findings in this study may facilitate more understanding on transport and fate of studied BDEs in soil systems. - Both linear distribution and nonlinear Freundlich model could well describe the sorption isotherms of PBDEs on natural soils.

  17. Dynamic Moisture Sorption and Desorption in Fumed Silica-filled Silicone Foam

    Energy Technology Data Exchange (ETDEWEB)

    Trautschold, Olivia Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-02

    Characterizing dynamic moisture sorption and desorption in fumed silica-filled silicone foam is necessary for determining material compatibilities and life predictions, particularly in sealed environments that may be exposed to a range of environmental conditions. Thermogravimetric analysis (TGA) and near infrared spectroscopy (NIR) were performed on S5470 fumed silica-filled silicone foam to determine the weight percent of moisture at saturation. Additionally, TGA was used to determine the time, temperature, and relative humidity levels required for sorption and desorption of physisorbed moisture in S5470.

  18. Basic density, extractive content and moisture sorption properties of Pinus pinaster wood infected with the pinewood nematode, Bursaphelenchus xylophilus

    Institute of Scientific and Technical Information of China (English)

    Valeria Reva; Luı´s Fonseca; Jose´ L. Lousada; Isabel Abrantes; Anto´ nio R. Figueiredo; Domingos X. Viegas

    2015-01-01

    The pinewood nematode (PWN), Bursaphe-lenchus xylophilus, has become one of the most severe threats to pine forest worldwide. Nematodes, migrating through resin canals and feeding on the living cells, induce rapid metabolic changes in ray parenchyma cells, create cavitation areas, decrease xylem water content and oleo-resin exudation, and cause necrosis of parenchyma and cambial cells. This study focused on the impact of PWN infection on technological parameters of wood and evalu-ated the impact of anatomic and biochemical incidences of tree defense reactions on basic density, extractive content and moisture sorption properties of Pinus pinaster wood. Samples of infected and uninfected wood were studied. The presence of nematodes reduced wood basic density by 2% and decreased the total content of extractives in infected wood as compared with uninfected (5.98 and 8.90% of dry wood mass, respectively). Extractives in infected trees had inverse distribution along the trunk as compared with uninfected trees. The adsorption isotherms for infected and uninfected wood had similar positioning. We recorded differences (some statistically significant) in the equilibrium moisture content of infected and uninfected wood under varying environmental conditions. Despite the verified differences in wood basic density, extractive con-tent and moisture sorption properties, the overall conclu-sion is that the PWN had a slight impact on these characteristics of wood.

  19. Sorption of norfloxacin in soils: analytical method, kinetics and Freundlich isotherms.

    Science.gov (United States)

    Peruchi, Livia Maniero; Fostier, Anne Hélène; Rath, Susanne

    2015-01-01

    Fluoroquinolones are potent antibacterial agents that are active against a wide range of pathogenic organisms and are widely used in veterinary medicine. Fluoroquinolones and their metabolites may reach the soil through animal excreta or manure and may contaminate water and soils. The degree of sorption of these antimicrobials to soils varies widely, as does the mobility of these drugs. In the present study, sorption of norfloxacin in four soils of the state of São Paulo was investigated with batch equilibrium experiments. A strong matrix effect on the chromatographic determination of norfloxacin was verified. Sorption kinetics were best fit by a pseudo second-order model (r>0.99), and sorption/desorption isotherms were well fit by the Freundlich model in log form (r>0.97). Norfloxacin showed high affinity for soil particles, with KF sorption values ranging from 643 to 2410 μg(1-1/n)(cm(3))(1/n)g(-1) and KF desorption values ranging from 686 to 2468 μg(1-1/n)(cm(3))(1/n)g(-1). The high desorption KF values indicate that norfloxacin is highly immobile in the evaluated soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. HYGROSCOPIC MOISTURE SORPTION KINETICS MODELING OF CORN STOVER AND ITS FRACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Igathinathane, C. [Mississippi State University (MSU); Pordesimo, L. O. [Mississippi State University (MSU); Womac, A.R. [University of Tennessee; Sokhansanj, Shahabaddine [ORNL

    2009-01-01

    Corn stover, a major crop-based lignocellulosic biomass feedstock, is required to be at an optimum moisture content for efficient bioconversion processes. Environmental conditions surrounding corn stover, as in storage facilities, affect its moisture due to hygroscopic sorption or desorption. The measurement and modeling of sorption characteristics of corn stover and its leaf, husk, and stalk fractions are useful from utilization and storage standpoints, hence investigated in this article. A benchtop low-temperature humidity chamber provided the test environments of 20 C, 30 C, and 40 C at a constant 95% relative humidity. Measured sorption characteristics with three replications for each fraction were obtained from instantaneous sample masses and initial moisture contents. Observed sorption characteristics were fitted using exponential, Page, and Peleg models. Corn stover fractions displayed a rapid initial moisture uptake followed by a slower sorption rates and eventually becoming almost asymptotic after 25 h. Sorption characteristics of all corn stover fractions were significantly different (P < 0.0001) but not the effect of temperature (P > 0.05) on these fractions. The initial 30 min of sorption was found to be critical due to peak rates of sorption from storage, handling, and processing standpoints. The Page and Peleg models had comparable performance fitting the sorption curves (R2 = 0.995), however the exponential model (R2 = 0.91) was not found suitable because of patterned residuals. The Arrhenius type relationship (P < 0.05; R2 = 0.80) explained the temperature variation of the fitted sorption model parameters. The Peleg model fitted constants, among the sorption models studied, had the best fit (R2 = 0.93) with the Arrhenius relationship. A developed method of mass proportion, involving individual corn stover fraction dry matter ratios, predicted the whole corn stover sorption characteristics from that of its individual fractions. Sorption

  1. Moisture sorption curves of fruit and nut cereal bar prepared with sugar and sugar substitutes

    OpenAIRE

    Pallavi, Byrappa Vasu; Chetana, Ramakrishna; Ravi, Ramaswamy; Reddy, Sunkireddy Yella

    2013-01-01

    Low sugar, low fat, dry fruit and nut cereal bars without sugar were prepared using cereals, nuts, and sugar substitutes. The sorption characteristics of the bars prepared with sugar substitutes in comparison with that of sugar were studied by keeping the bars at water activity (aw) from 0.1 to 0.9. The sorption isotherms of low sugar bars were practically identical below aw of 0.5 but above aw of 0.5, a clear differentiation in the isotherms could be observed compared to that of sugar counte...

  2. Effectiveness of Protective Action of Coatings from Moisture Sorption into Surface Layer of Sand Moulds

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2016-12-01

    Full Text Available The results of investigations of the sorption process of surface layers of sand moulds covered by zirconium and zirconium - graphite alcohol coatings are presented in the paper. Investigations comprised two kinds of sand grains (silica sand and reclaimed sand of moulding sand with furan resin. Tests were performed under conditions of a high relative air humidity 75 - 85% and a constant temperature within the range 28 – 33°C. To evaluate the effectiveness of coatings protective action from moisture penetration into surface layers of sand moulds gravimetric method of quantitavie moisture sorption and ultrasonic method were applied in measurements.

  3. Dynamic wetting on a thin film of soluble polymer: effects of nonlinearities in the sorption isotherm.

    Science.gov (United States)

    Dupas, Julien; Verneuil, Emilie; Ramaioli, Marco; Forny, Laurent; Talini, Laurence; Lequeux, Francois

    2013-10-08

    The wetting dynamics of a solvent on a soluble substrate interestingly results from the rates of the solvent transfers into the substrate. When a supported film of a hydrosoluble polymer with thickness e is wet by a spreading droplet of water with instantaneous velocity U, the contact angle is measured to be inversely proportionate to the product of thickness and velocity, eU, over two decades. As for many hydrosoluble polymers, the polymer we used (a polysaccharide) has a strongly nonlinear sorption isotherm φ(a(w)), where φ is the volume fraction of water in the polymer and aw is the activity of water. For the first time, this nonlinearity is accounted for in the dynamics of water uptake by the substrate. Indeed, by measuring the water content in the polymer around the droplet φ at distances as small as 5 μm, we find that the hydration profile exhibits (i) a strongly distorted shape that results directly from the nonlinearities of the sorption isotherm and (ii) a cutoff length ξ below which the water content in the substrate varies very slowly. The nonlinearities in the sorption isotherm and the hydration at small distances from the line were not accounted for by Tay et al., Soft Matter 2011, 7, 6953. Here, we develop a comprehensive description of the hydration of the substrate ahead of the contact line that encompasses the two water transfers at stake: (i) the evaporation-condensation process by which water transfers into the substrate through the atmosphere by the condensation of the vapor phase, which is fed by the evaporation from the droplet itself, and (ii) the diffusion of liquid water along the polymer film. We find that the eU rescaling of the contact angle arises from the evaporation-condensation process at small distances. We demonstrate why it is not modified by the second process.

  4. Isothermal and non-isothermal crystallization in amorphous sucrose and lactose at low moisture contents.

    Science.gov (United States)

    Kedward, C J; MacNaughtan, W; Mitchell, J R

    2000-11-03

    Differential scanning calorimetry has been used in isothermal and non-isothermal modes to provide information on the crystallization of sucrose and lactose at low water contents. Using approaches previously applied to polymer crystallization an attempt has been made to combine the isothermal and non-isothermal data into a single curve. This is achieved by the use of appropriate shift factors in the time and temperature domains. This was successful for sucrose but not for lactose. It was suggested that this was because lactose crystallizes into multiple forms whereas sucrose crystallizes in a single form.

  5. Isotherms and isosteric heat of sorption of two varieties of Peruvian quinoa

    Directory of Open Access Journals (Sweden)

    Augusto Pumacahua-Ramos

    2016-01-01

    Full Text Available The isosteric heats of sorption of two varieties of quinoa (Chenopodium quinoaWilld. grain were determined by the static gravimetric method at four temperatures (40, 50, 60 and 70 °C andin relative humidity environments provided by six saturated salt solutions. Six mathematical equations were used to model the experimental data: GAB, Oswin, Henderson, Peleg, Smith and Halsey. The isosteric heat of sorption was determined using the parameters of the GAB model. All the equations were shown to be appropriate by the coefficients of determination (R2 and the mean absolute error (MA%E. The influence of temperature was observed because the adsorption of water by the grains was lower at highertemperatures. The equilibrium moisture contents for security of storage, for long periods of time at water activity lower than 0.65, were 12 -13%. The effect of temperature on the parameters of the GAB model was analysed using the exponential Arrhenius equation. The isosteric heats of sorption were determined by applying the Clausius-Clapeyron equation as a function of humidity. The isosteric heat at 5% moisture for grains of the Blanca de Juli variety was 3663 kJ/kg and for the Pasankalla variety it was 3393 kJ/kg. The experimental data for isosteric heat as a function of humidity were satisfactorily modelled using three mathematical equations.

  6. Isotherm investigation for the sorption of fluoride onto Bio-F: comparison of linear and non-linear regression method

    Science.gov (United States)

    Yadav, Manish; Singh, Nitin Kumar

    2017-08-01

    A comparison of the linear and non-linear regression method in selecting the optimum isotherm among three most commonly used adsorption isotherms (Langmuir, Freundlich, and Redlich-Peterson) was made to the experimental data of fluoride (F) sorption onto Bio-F at a solution temperature of 30 ± 1 °C. The coefficient of correlation (r2 ) was used to select the best theoretical isotherm among the investigated ones. A total of four Langmuir linear equations were discussed and out of which linear form of most popular Langmuir-1 and Langmuir-2 showed the higher coefficient of determination (0.976 and 0.989) as compared to other Langmuir linear equations. Freundlich and Redlich-Peterson isotherms showed a better fit to the experimental data in linear least-square method, while in non-linear method Redlich-Peterson isotherm equations showed the best fit to the tested data set. The present study showed that the non-linear method could be a better way to obtain the isotherm parameters and represent the most suitable isotherm. Redlich-Peterson isotherm was found to be the best representative (r2 = 0.999) for this sorption system. It is also observed that the values of β are not close to unity, which means the isotherms are approaching the Freundlich but not the Langmuir isotherm.

  7. Effect of Durability Treatment on Moisture Sorption Properties of Wood-Plastic Composites

    Directory of Open Access Journals (Sweden)

    Huiyuan Li

    2014-09-01

    Full Text Available In this study, water absorption and desorption behaviors of wood-plastic composites (WPCs treated with ultraviolet agents and zinc borate were investigated. Water diffusion characteristics in the composites were analyzed using a one-dimensional diffusion model. The mechanism of water sorption for all composites deviated from Fick’s law of diffusion. Much larger diffusion coefficient values are observed from the desorption process when compared to the absorption process. Measured final equilibrium moisture content and calculated diffusion coefficients varied with sample formulation in a non-consistent manner; this indicated that the durability treatment used in the current study did not negatively affect the water sorption behavior of WPCs. The results of this study help to clarify the effect of durability treatment on the dynamic moisture sorption process of WPCs.

  8. Phosphate sorption by three potential filter materials as assessed by isothermal titration calorimetry.

    Science.gov (United States)

    Lyngsie, Gry; Penn, Chad J; Hansen, Hans C B; Borggaard, Ole K

    2014-10-01

    Phosphorus eutrophication of lakes and streams, coming from drained farmlands, is a serious problem in areas with intensive agriculture. Installation of phosphate (P) sorbing filters at drain outlets may be a solution. The aim of this study was to improve the understanding of reactions involved in P sorption by three commercial P sorbing materials, i.e. Ca/Mg oxide-based Filtralite-P, Fe oxide-based CFH-12 and Limestone in two particle sizes (2-1 mm and 1-0.5 mm), by means of isothermal titration calorimetry (ITC), sorption isotherms, sequential extractions and SEM-EDS. The results indicate that P retention by CFH is due to surface complexation by rapid formation of strong Fe-P bonds. In contrast, retention of P by Filtralite-P and Limestone strongly depends on pH and time and is interpreted due to formation of calcium phosphate precipitate(s). Consequently, CFH can unambiguously be recommended as P retention filter material in drain outlets, whereas the use of Filtralite-P and Limestone has certain (serious) limitations. Thus, Filtralite-P has high capacity to retain P but only at alkaline pH (pH ≥ 10) and P retention by Limestone requires long-time contact and a high ratio between sorbent and sorbate.

  9. Sorption of organic compounds to activated carbons. Evaluation of isotherm models

    Energy Technology Data Exchange (ETDEWEB)

    Pikaar, I.; Koelmans, A.A.; van Noort, P.C.M. [RIZA, Lelystad (Netherlands). Inst. of Inland Water Management & Wastewater Treatment

    2006-12-15

    Sorption to 'hard carbon' (black carbon, coal, kerogen) in soils and sediments is of major importance for risk assessment of organic pollutants. We argue that activated carbon (AC) may be considered a model sorbent for hard carbon. Here, we evaluate six sorption models on a literature dataset for sorption of 12 compounds onto 12 ACs and one charcoal, at different temperatures (79 isotherms in total). A statistical analysis, accounting for differences in the number of fitting parameters, demonstrates that the dual Langmuir equation is in general superior and/or preferable to the single and triple Langmuir equation, the Freundlich equation, a Polanyi-Dubinin-Manes equation, and the Toth equation. Consequently, the analysis suggests the presence of two types of adsorption sites: a high-energy (HE) type of site and a low-energy (LE) type of site. Maximum adsorption capacities for the HE domain decreased with temperature while those for the LE domain increased. Average Gibbs free energies for adsorption from the hypothetical pure liquid state at 298 K were fairly constant at - 15 {+-} 4 and -5 {+-} 4 kJ mol{sup -1} for the HE and LE domain, respectively.

  10. Isothermal Adsorption Measurement for the Development of High Performance Solid Sorption Cooling System

    Science.gov (United States)

    Saha, Bidyut Baran; Koyama, Shigeru; Alam, K. C. Amanul; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao; Ng, Kim Choon; Chua, Hui Tong

    Interest in low-grade thermal heat powered solid sorption system using natural refrigerants has been increased. However, the drawbacks of these adsorption systems are their poor performance. The objective of this paper is to improve the performance of thermally powered adsorption cooling system by selecting new adsorbent-refrigerant pairs. Adsorption capacity of adsorbent-refrigerant pair depends on the thermophysical properties (pore size, pore volume and pore diameter) of adsorbent and isothermal characteristics of the adsorbent-refrigerant pair. In this paper, the thermophysical properties of three types of silica gels and three types of pitch based activated carbon fibers are determined from the nitrogen adsorption isotherms. The standard nitrogen gas adsorption/desorption measurements on various adsorbents at liquid nitrogen of temperature 77.4 K were performed. Surface area of each adsorbent was determined by the Brunauer, Emmett and Teller (BET) plot of nitrogen adsorption data. Pore size distribution was measured by the Horvath and Kawazoe (HK) method. Adsorption/desorption isotherm results showed that all three carbon fibers have no hysteresis and had better adsorption capacity in comparison with those of silica gels.

  11. Idealized Shale Sorption Isotherm Measurements to Determine Pore Volume, Pore Size Distribution, and Surface Area

    Science.gov (United States)

    Holmes, R.; Wang, B.; Aljama, H.; Rupp, E.; Wilcox, J.

    2014-12-01

    One method for mitigating the impacts of anthropogenic CO2-related climate change is the sequestration of CO2 in depleted gas and oil reservoirs, including shale. The accurate characterization of the heterogeneous material properties of shale, including pore volume, surface area, pore size distributions (PSDs) and composition is needed to understand the interaction of CO2 with shale. Idealized powdered shale sorption isotherms were created by varying incremental amounts of four essential components by weight. The first two components, organic carbon and clay, have been shown to be the most important components for CO2 uptake in shales. Organic carbon was represented by kerogen isolated from a Silurian shale, and clay groups were represented by illite from the Green River shale formation. The rest of the idealized shale was composed of equal parts by weight of SiO2 to represent quartz and CaCO3 to represent carbonate components. Baltic, Eagle Ford, and Barnett shale sorption measurements were used to validate the idealized samples. The idealized and validation shale sorption isotherms were measured volumetrically using low pressure N2 (77K) and CO2 (273K) adsorbates on a Quantachrome Autosorb IQ2. Gravimetric isotherms were also produced for a subset of these samples using CO2 and CH4adsorbates under subsurface temperature and pressure conditions using a Rubotherm magnetic suspension balance. Preliminary analyses were inconclusive in validating the idealized samples. This could be a result of conflicting reports of total organic carbon (TOC) content in each sample, a problem stemming from the heterogeneity of the samples and different techniques used for measuring TOC content. The TOC content of the validation samples (Eagle Ford and Barnett) was measured by Rock-Eval pyrolysis at Weatherford Laboratories, while the TOC content in the Baltic validation samples was determined by LECO TOC. Development of a uniform process for measuring TOC in the validation samples is

  12. Mathematical modeling of handmade recycled paper drying kinetics and sorption isotherms

    Directory of Open Access Journals (Sweden)

    M. G. A. Vieira

    2008-06-01

    Full Text Available The objective of this work is to analyze and compare the natural and forced convective drying of handmade recycled paper. Drying of recycled cellulose pulp was carried out under laboratory environment conditions and in a convective dryer with forced air circulation and controlled conditions of air temperature and velocity. The tests were conducted following a two-factor central composed factorial design of experiments, with six runs at the central point. The drying results were analyzed and fitted to mathematical models of Fick, Henderson and Pabis (Fick’s modified equation, Page and He (considering the nonlinear Fick effect. The model of Page represented best the experimental data and the one of Henderson and Pabis resulted in an adequate fit for the paper drying kinetics. Sorption isotherms were determined for the dried paper and the models of GAB (Guggenheim-Anderson-de Boer and GDW (Generalised D’Arcy and Watt resulted in excellent fits of the experimental data. The water sorption mechanism was suggested by the analysis of the calculated parameters of the GDW model.

  13. Sorption of alkylphenols on Ebro River sediments: Comparing isotherms with field observations in river water and sediments

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Alicia [Center of Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen (Germany); Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain)], E-mail: anoqam@iiqab.csic.es; Endo, Satoshi; Gocht, Tilman [Center of Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen (Germany); Barth, Johannes A.C. [Center of Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen (Germany); Lehrstuhl fuer Angewandte Geologie, GeoZentrum Nordbayern, Universitaet Erlangen-Nuernberg, Schlossgarten 5, 91054 Erlangen (Germany); Lacorte, Silvia [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Barcelo, Damia [Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Institut Catala de Recerca de l' Aigua (ICRA), Parc Cientific i Tecnologic de la Universitat de Girona, Pic de Peguera, 15, 17003 Girona (Spain); Grathwohl, Peter [Center of Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen (Germany)

    2009-02-15

    This study reports sorption isotherms of the endocrine disruptors nonylphenol (NP) and octylphenol (OP) in three sediment samples from the Ebro River basin (NE Spain), with organic carbon fractions (f{sub OC}) ranging from 0.0035 to 0.082 g{sub OC} g{sup -1}. All isotherms were fitted to the Freundlich model with slightly nonlinear exponents ranging from 0.80 to 0.94. The solubility of the compounds as well as the organic carbon (OC) content had the strongest influences on the sorption behavior of these compounds. Comparison of the laboratory-spiked samples with the native contamination of NP of 45 water and concurrent sediment samples resulted in reasonable matches between both data sets, even though the lowest concentrations in the field were not completely reached in laboratory tests. This good agreement indicates that sorption laboratory data can be extrapolated to environmental levels and therefore the distribution of nonylphenol between sediments and water can be predicted with a precision of one order of magnitude. Furthermore, laboratory experiments with simultaneous loading of NP and OP revealed negligible competition for sorption sites at low concentrations. - Laboratory sorption of nonylphenol compared to field concentrations showed good agreements.

  14. Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

    Science.gov (United States)

    Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu

    2016-07-15

    The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values.

  15. Comparison of distribution coefficients (K{sub d} values), sorption isotherms and surface complexation models for evaluating radionuclide sorption in geological media

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Timothy E. [Australian Nuclear Science and Technology Organisation (ANSTO), Menai (Australia); Waite, T. David [School of Civil and Environmental Engineering, University of New South Wales, Sydney (Australia)

    1999-07-01

    The safety assessment of repositories requires models of sorption to be included in the computer codes used for predicting radionuclide migration. Typically, these codes rely on the distribution coefficient (K{sub d} value) to describe sorption. In this paper, the sorption behaviour of U is used as a case study for the development of different types of sorption models. Adsorption isotherms relate the amount of absorbed radionuclide to its dissolved concentration, but usually can not account for the effects of variables such as the pH, ionic strength or the presence of complexing ligands without adjustment of parameter values. The surface complexation model (SCM) offers a more fundamental description of sorption, but requires a large experimental data base, with systematic variation of parameters such as pH and radionuclide concentration. Model uncertainties that derive from the experimental data must be taken into account. The SCM can be used to constrain the range of radionuclide K{sub d} values that may occur in a given environment. (author)

  16. Fluoride Sorption Efficiency of Vermiculite Functionalised with Cationic Surfactant: Isotherm and Kinetics

    Directory of Open Access Journals (Sweden)

    Tayo Oladipo Ologundudu

    2016-09-01

    Full Text Available Groundwater is a major source of water, especially in rural communities. The presence of excess fluoride in groundwater has been a health concern for many decades because it causes fluorosis. The persistence of this problem led to the development of several approaches for reducing fluoride in groundwater to ≤1.5 mg/L, which is the World Health Organization’s (WHO permissible limit. Despite recorded success in fluoride reduction, drawbacks such as cost and efficiency have remained apparent, thus necessitating further research on defluoridation. This paper aims at assessing the defluoridation capacity of a clay mineral, vermiculite, when modified with the cationic surfactant hexadecyltrimethylammonium bromide. The effects of experimental parameters such as pH, agitation time, mass of adsorbent, and temperature were examined to determine the most favourable adsorption conditions. Using batch technique, the results showed a fluoride sorption of 51% from an 8 mg/L fluoride solution. The adsorption conformed more to Freundlich than Langmuir isotherm with an adsorption capacity of 2.36 mg/g, while the kinetics conformed to a pseudo-second-order reaction. pH emerged as the most influential factor in optimisation. The findings of this study indicated that modified vermiculite could be efficient in reducing fluoride in groundwater to more tolerable limits, but requires adequate pH control.

  17. Humidity scanning quartz crystal microbalance with dissipation monitoring setup for determination of sorption-desorption isotherms and rheological changes

    Energy Technology Data Exchange (ETDEWEB)

    Björklund, Sebastian, E-mail: sebastianbjorklund@gmail.com; Kocherbitov, Vitaly [Department of Biomedical Science, Faculty of Health and Society, Malmö University, Malmö (Sweden); Biofilms—Research Center for Biointerfaces, Malmö University, Malmö (Sweden)

    2015-05-15

    A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtone dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.

  18. Effect of soil moisture on the sorption of trichloroethene vapor to vadose-zone soil at picatinny arsenal, New Jersey

    Science.gov (United States)

    Smith, J.A.; Chiou, C.T.; Kammer, J.A.; Kile, D.E.

    1990-01-01

    This report presents data on the sorption of trichloroethene (TCE) vapor to vadose-zone soil above a contaminated water-table aquifer at Picatinny Arsenal in Morris County, NJ. To assess the impact of moisture on TCE sorption, batch experiments on the sorption of TCE vapor by the field soil were carried out as a function of relative humidity. The TCE sorption decreases as soil moisture content increases from zero to saturation soil moisture content (the soil moisture content in equilibrium with 100% relative humidity). The moisture content of soil samples collected from the vadose zone was found to be greater than the saturation soil-moisture content, suggesting that adsorption of TCE by the mineral fraction of the vadose-zone soil should be minimal relative to the partition uptake by soil organic matter. Analyses of soil and soil-gas samples collected from the field indicate that the ratio of the concentration of TCE on the vadose-zone soil to its concentration in the soil gas is 1-3 orders of magnitude greater than the ratio predicted by using an assumption of equilibrium conditions. This apparent disequilibrium presumably results from the slow desorption of TCE from the organic matter of the vadose-zone soil relative to the dissipation of TCE vapor from the soil gas.

  19. Moisture sorption, biological durability, and mechanical performance of WPC containing modified wood and polylactates

    Directory of Open Access Journals (Sweden)

    B. Kristoffer Segerholm

    2012-11-01

    Full Text Available Biological durability is an important feature for wood-plastic composites (WPC intended for outdoor applications. One route to achieving WPC products with increased biological durability is to use wood preservative agents in the formulation of the WPC. Another option could be to use a chemically modified wood component that already exhibits increased resistance to biological degradation. There is also a need to use biobased thermoplastics made from renewable resources, which would decrease the dependency on petrochemically-produced thermoplastics in the future. The objective of this study was to examine moisture sorption properties, biological durability, and mechanical performance of injection-molded WPC samples based on acetylated or thermally modified wood components and a polylactate matrix. The biological durability was evaluated in a terrestrial microcosm (TMC test according to ENV 807, followed by mechanical evaluation in a center point bending test. The moisture sorption properties were investigated via both water soaking and exposure in a high-humidity climate. Low or negligible mass losses were observed in the TMC test for all WPC samples. However, the mechanical evaluation after exposure in the TMC test showed 35-40% losses in both strength and stiffness for the WPC containing an unmodified wood component.

  20. Sorption of organic compounds to activated carbons. Evaluation of isotherm models

    NARCIS (Netherlands)

    Pikaar, I.; Koelmans, A.A.; Noort, van P.C.M.

    2006-01-01

    Sorption to 'hard carbon' (black carbon, coal, kerogen) in soils and sediments is of major importance for risk assessment of organic pollutants. We argue that activated carbon (AC) may be considered a model sorbent for hard carbon. Here, we evaluate six sorption models on a literature dataset for so

  1. Moisture-swing sorption for carbon dioxide capture from ambient air: a thermodynamic analysis.

    Science.gov (United States)

    Wang, Tao; Lackner, Klaus S; Wright, Allen B

    2013-01-14

    An ideal chemical sorbent for carbon dioxide capture from ambient air (air capture) must have a number of favourable properties, such as environmentally benign behaviour, a high affinity for CO(2) at very low concentration (400 ppm), and a low energy cost for regeneration. The last two properties seem contradictory, especially for sorbents employing thermal swing adsorption. On the other hand, thermodynamic analysis shows that the energy cost of an air capture device need only be slightly larger than that of a flue gas scrubber. The moisture swing separation process studied in this paper provides a novel approach to low cost CO(2) capture from air. The anionic exchange resin sorbent binds CO(2) when dry and releases it when wet. A thermodynamic model with coupled phase and chemical equilibria is developed to study the complex H(2)O-CO(2)-resin system. The moisture swing behaviour is compatible with hydration energies changing with the activity of water on the resin surfaces. This activity is in turn set by the humidity. The rearrangement of hydration water on the resin upon the sorption of a CO(2) molecule is predicted as a function of the humidity and temperature. Using water as fuel to drive the moisture swing enables an economical, large-scale implementation of air capture. By generating CO(2) with low partial pressures, the present technology has implications for in situ CO(2) utilizations which require low pressure CO(2) gas rather than liquid CO(2).

  2. Experimental assessment of the spatial variability of porosity, permeability and sorption isotherms in an ordinary building concrete

    Science.gov (United States)

    Issaadi, N.; Hamami, A. A.; Belarbi, R.; Aït-Mokhtar, A.

    2017-10-01

    In this paper, spatial variabilities of some transfer and storage properties of a concrete wall were assessed. The studied parameters deal with water porosity, water vapor permeability, intrinsic permeability and water vapor sorption isotherms. For this purpose, a concrete wall was built in the laboratory and specimens were periodically taken and tested. The obtained results allow highlighting a statistical estimation of the mean value, the standard deviation and the spatial correlation length of the studied fields for each parameter. These results were discussed and a statistical analysis was performed in order to assess for each of these parameters the appropriate probability density function.

  3. Calculation of Safe Moisture and Isosteric Heat of Sorption in Rice Grains%大米安全水分和吸着等热计算

    Institute of Scientific and Technical Information of China (English)

    张元娣; 秦文; 李兴军

    2011-01-01

    对静态称重法测定的5个大米样品吸着等温线数据,分别采用Brunauer - Emmett - Teller (BET)、CAE、修正Chung - Pfost (MCPE)、修正Guggenhein - Anderson - de Boer( MGAB)、修正Henderson、修正Oswin及Strohman - Yoerger 7个方程进行拟合,MCPE被判定为大米最佳吸着等温线方程.以M=f(hr,t)形式表达的平均解吸等温线方程MCPE的3个参数C1、C2及C3各是492.539、39.846及0.176,在RH 70%下,对应的10、15、20、25、30、35℃条件下大米样品平均解吸值,分别是15.88%、15.49%、15.13%、14.80%、14.50%及14.21%.3个粳米(方正香米、东北普通米、松花江米)在25℃的安全水分是14.92% ~ 15.39%,低于15.5%;2个籼米(泰国香米和江苏米)安全水分则是13.88%~14.43%,低于14.5%,与GB 1354-2009大米限量水分一致.大米吸着等热在含水率<20%干基条件下,随着米粒含水率增加而快速减少,在高于20%干基含水率则随含水率增加而缓慢减少.在含水率<22.5%干基条件下,较低温度下的大米吸附等热与解吸等热均高于较高温度;大米解吸等热高于吸附等热,但是随着含水率增加则差异减少.%The sorption isotherm data of 5 rice samples determined by the static weighting method were respectively fitted with 7 equations as Brunauer - Emmett - Teller (BET), CAE, Modified Chung - Pfost (MCPE ) , Modified Guggenhein - Anderson - de Boer ( MGAB), Modified Henderson, Modified Oswin and Strohman - Yoerger, and MCPE was determined as the optimum sorption isotherm equation for the rice. In M =f(hr,t) average sorption isotherm equation ,3 MCPE parameters of C1, C2 and C3 are respectively 492.539,39.846 and 0.176. Under RH 70% , the average sorption values under corresponding 10,15,20,25,30 and 35 ℃ were respectively 15.88% ,15.49% , 15.13% , 14. 80% , 14.50% and 14.21 %. The safe moistures of 3 non - glutinous rice samples ( Fangzheng japonica rice, Northeast common rice and

  4. A Numerical Approach for Non-Linear Moisture Flow in Porous Materials with Account to Sorption Hysteresis

    DEFF Research Database (Denmark)

    Johannesson, Björn; Nyman, U.

    2010-01-01

    A numerical approach for moisture transport in porous materials like concrete is presented. The model considers mass balance equations for the vapour phase and the water phase in the material together with constitutive equations for the mass flows and for the exchange of mass between the two phases....... History-dependent sorption behaviour is introduced by considering scanning curves between the bounding desorption and absorption curves. The method, therefore, makes it possible to calculate equilibrium water contents for arbitrary relative humidity variations at every material point considered......-Raphson equilibrium iteration scheme within the time steps. Examples are presented illustrating the performance and potential of the model. Two different types of measurements on moisture content profiles in concrete are used to verify the relevance of the novel proposed model for moisture transport and sorption...

  5. Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

    NARCIS (Netherlands)

    Hullebusch, van E.D.; Peerbolte, A.; Zandvoort, M.H.; Lens, P.N.L.

    2005-01-01

    The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH = 7) were loaded with nickel and cobalt in. adsorption experiments (monometal and competitive

  6. Mild hydration of didecyldimethylammonium chloride modified DNA by 1H-nuclear magnetic resonance and by sorption isotherm

    Science.gov (United States)

    Harańczyk, H.; Kobierski, J.; Nizioł, J.; Hebda, E.; Pielichowski, J.; Zalitacz, D.; Marzec, M.; El-Ghayoury, A.

    2013-01-01

    The gaseous phase hydration of deoxyribonucleic acid and didecyldimethylammonium chloride (C19H42ClN) complexes (DNA-DDCA) was observed using hydration kinetics, sorption isotherm, and high power nuclear magnetic resonance. Three bound water fractions were distinguished: (i) a very tightly bound water not removed by incubation over silica gel, (ii) a tightly bound water saturating with the hydration time t1h = (0.59 ± 0.04) h, and a loosely bound water fraction, (iii) with the hydration time t2h = (20.9 ± 1.3) h. Proton free induction decay was decomposed into the signal associated with the solid matrix of DNA-DDCA complex (T2S∗≈ 30 μs) and two liquid signal components coming from tightly bound (T2L1∗≈ 100 μs) and from loosely bound water fraction (T2L2∗≈ 1000 μs).

  7. PENGEMBANGAN PRODUK MI KERING DARI TEPUNG UBI JALAR (Ipomoea batatas DAN PENENTUAN UMUR SIMPANNYA DENGAN METODE ISOTERM SORPSI [Development of Dried Noodle Made of Sweet Potato (Ipomoea batatas Flour and Prediction of Its Shelf Life Using Sorption Isotherm Method

    Directory of Open Access Journals (Sweden)

    Sugiyono1*

    2011-12-01

    Full Text Available The objective of this research was to develop dried noodle product made of sweet potato flour and to predict its shelf life using sorption isotherm method. The product was produced through gelatinization of dough, followed by sheeting, steaming, and drying. The best quality product was produced through gelatinization for 20 minutes followed by steaming for 10 minutes. The best quality product had 5.86% moisture, 3.10% ash, 0.23% fat, 2.66% protein, and 88.15% carbohydrate. The product had 54.43 degree of whiteness, 28.75 gf of elasticity, 3.5 minutes of rehydration time, 53.23% of water absorption capacity, and 14.85% of cooking loss. The sorption isotherm curve of the product was best described by Henderson model. The shelf lives of the packed product in low density polyethylene, medium density polyethylene, high density polyethylene, and polypropylene at 80% RH were calculated to be 55, 92, 277 and 150 days respectively.

  8. Histerese das isotermas de sorção da polpa de manga (Mangifera indica L. variedade manteiga Hysteresis of the sorption isotherms of mango pulp (Mangifera indica L. manteiga variety

    Directory of Open Access Journals (Sweden)

    Camila de S. Paglarini

    2013-03-01

    Full Text Available As isotermas de sorção são de grande importância para predizer processos de secagem e armazenamento de um produto. A histerese é um fenômeno que ocorre devido à diferença entre as curvas de adsorção e dessorção. O presente trabalho teve o objetivo de analisar a influência da temperatura nas isotermas de sorção e na histerese da polpa de manga variedade manteiga. As isotermas foram determinadas pelo método gravimétrico estático, com a utilização de diferentes concentrações ácidas, nas temperaturas de 20, 30, 40 e 50 °C e atividade de água variando de 4,3 a 88,8% até atingir a umidade de equilíbrio. Foram analisados seis modelos matemáticos para isotermas de sorção (GAB, BET, Halsey, Henderson-Thompson, Oswin e Luikov ajustados aos dados experimentais, através de regressão não-linear. A histerese foi calculada pela área compreendida entre as curvas de dessorção e adsorção. De acordo com os resultados obtidos o modelo de GAB foi o que melhor se ajustou às isotermas de equilíbrio da manga. A área da histerese reduziu 51% entre as temperaturas de 20 e 50 °C.The sorption isotherms are of great importance for predicting drying and storage of a product. Hysteresis is a phenomenon that occurs due to the difference between the curves of adsorption and desorption. This study aimed to analyse the influence of temperature on sorption isotherms and hysteresis of mango pulp manteiga variety. The isotherms were determined by the static method with the use of different acid concentrations. The samples were submitted to temperatures of 20, 30, 40 and 50 °C and water activity ranging from 4.3 to 88.8% until the equilibrium moisture content. Six mathematical models for the sorption isotherms (GAB, BET, Halsey, Henderson-Thompson, Oswin and Luikov were analysed and adjusted to the experimental data using nonlinear regression. The hysteresis was calculated as the area between the curves of adsorption and desorption

  9. PENENTUAN WAKTU KADALUARSA DAN MODEL SORPSI ISOTERMIS BIJI DAN BUBUK LADA HITAM (Piper ningrum L. [Shelf Life Prediction and Isotherm Sorption Model of Dried Grain and Powdered Black Pepper (Piper ningrum L.

    Directory of Open Access Journals (Sweden)

    Erika Diah2

    2005-04-01

    Full Text Available Black pepper is one of the most popular spice traded around the globe, either in dried grain form or in bulky powder. However, for retailing purpose both are usually packaged in plastic film. This research was conducted to predict the shelf life of packaged black pepper (both dried grain and powder by applying isotherm sorption and Labuza models. Initial moisture content of dried grain was 12.17 % d.b and for the powder was 10.27 % d.b. The shelf life of black pepper calculated for the dried grain was longer than the powder. When stored at 90 % RH, the dried grain black pepper packaged in HDPE demonstrated the longest shelf life which was equal to 2187 days and for the powder equal to 2037 days. The volatile oil loss for dried grain black pepper after 30 days of preservation was 1.36 % and for the powder was 40.82%.

  10. A two-phase moisture transport model accounting for sorption hysteresis in layered porous building constructions

    DEFF Research Database (Denmark)

    Johannesson, Björn; Janz, Mårten

    2009-01-01

    , with account also to sorption hysteresis. The different materials in the considered layered construction are assigned different properties, i.e. vapor and liquid water diffusivities and boundary (wetting and drying) sorption curves. Further, the scanning behavior between wetting and drying boundary curves...

  11. Sorption studies of heavy metal ions by salicylic acid–formaldehyde–catechol terpolymeric resin: Isotherm, kinetic and thermodynamics

    Directory of Open Access Journals (Sweden)

    Riddhish R. Bhatt

    2015-05-01

    Full Text Available Terpolymeric resin has been synthesized by condensing salicylic acid with catechol employing formaldehyde as a cross linking agent at 80 ± 5 °C using DMF as a solvent. The resin was characterized by elemental analysis, FTIR, XRD and thermal analysis (TGA, DTA and DTG. The morphology of the resin was studied by optical photographs and scanning electron micrographs (SEM at different magnifications. The physico-chemical properties have been studied. The uptake behavior of various metal ions viz. Ni(II, Cu(II, Zn(II, Cd(II and Pb(II towards synthesized resin has been studied depending on contact time, pH and temperature. The selectivity order found is: Cu(II > Zn(II > Pb(II > Ni(II > Cd(II. The sorption data obtained at optimized conditions were analyzed by six two parameter isotherm models like Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R, Halsey and Harkins–Jura. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R isotherms were found better to describe the sorption data with high correlation for the adsorption with a low SSE value for all the metals under study. The adsorption capacities of the SFC resin for removal of Ni(II, Cu(II, Zn(II, Cd(II and Pb(II were determined with the Langmuir equation and found to be 0.815, 1.104, 1.215, 0.498, and 0.931 mmol/g respectively. The adsorption process follows first order kinetics and specific rate constant Kr was obtained by the application of Lagergren equation. Thermodynamic parameters viz. ΔGads, ΔSads and ΔHads have also been calculated for the metal-resin systems. The external diffusion rate constant (Ks and intra-particle diffusion rate constant (Kid were calculated by Spahn–Schlunder and Weber–Morris models respectively. Desorption studies were done using various desorbing agents viz. de-ionized water, boiled water, various concentrations of HCl, ammonia, thiourea, citric acid and tartaric acid.

  12. Capillary Condensation, Freezing, and Melting in Silica Nanopores: A Sorption Isotherm and Scanning Calorimetry Study on Nitrogen in Mesoporous SBA-15

    CERN Document Server

    Moerz, Sebastian T; Huber, Patrick; 10.1103/PhysRevB.85.075403

    2012-01-01

    Condensation, melting and freezing of nitrogen in a powder of mesoporous silica grains (SBA-15) has been studied by combined volumetric sorption isotherm and scanning calorimetry measurements. Within the mean field model of Saam and Cole for vapor condensation in cylindrical pores a liquid nitrogen sorption isotherm is well described by a bimodal pore radius distribution. It encompasses a narrow peak centered at 3.3 nm, typical of tubular mesopores, and a significantly broader peak characteristic of micropores, located at 1 nm. The material condensed in the micropores as well as the first two adsorbed monolayers in the mesopores do not exhibit any caloric anomaly. The solidification and melting transformation affects only the pore condensate beyond approx. the second monolayer of the mesopores. Here, interfacial melting leads to a single peak in the specific heat measurements. Homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the mesopores result in a caloric fr...

  13. Sorption isotherms, thermodynamic properties and glass transition temperature of mucilage extracted from chia seeds (Salvia hispanica L.).

    Science.gov (United States)

    Velázquez-Gutiérrez, Sandra Karina; Figueira, Ana Cristina; Rodríguez-Huezo, María Eva; Román-Guerrero, Angélica; Carrillo-Navas, Hector; Pérez-Alonso, César

    2015-05-05

    Freeze-dried chia mucilage adsorption isotherms were determined at 25, 35 and 40°C and fitted with the Guggenheim-Anderson-de Boer model. The integral thermodynamic properties (enthalpy and entropy) were estimated with the Clausius-Clapeyron equation. Pore radius of the mucilage, calculated with the Kelvin equation, varied from 0.87 to 6.44 nm in the temperature range studied. The point of maximum stability (minimum integral entropy) ranged between 7.56 and 7.63kg H2O per 100 kg of dry solids (d.s.) (water activity of 0.34-0.53). Enthalpy-entropy compensation for the mucilage showed two isokinetic temperatures: (i) one occurring at low moisture contents (0-7.56 kg H2O per 100 kg d.s.), controlled by changes in water entropy; and (ii) another happening in the moisture interval of 7.56-24 kg H2O per 100 kg d.s. and was enthalpy driven. The glass transition temperature Tg of the mucilage fluctuated between 42.93 and 57.93°C.

  14. Natural composites: Strength, packing ability and moisture sorption of cellulose fibres, and the related performance of composites

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2012-01-01

    Biobased materials are becoming of increasing interest as potential structural materials for the future. A useful concept in this context is the fibre reinforcement of materials by stiff and strong fibres. The bio-resources can contribute with cellulose fibres and (bio) polymers from hemicellulos...... in stiffness, on the packing ability of cellulose fibres and the related maximum fibre volume fraction in composites, on the moisture sorption of cellulose fibres and the related mass increase and (large) hygral strains induced, and on the mechanical performance of composites....

  15. Comparison of linear and non-linear method in estimating the sorption isotherm parameters for safranin onto activated carbon.

    Science.gov (United States)

    Kumar, K Vasanth; Sivanesan, S

    2005-08-31

    Comparison analysis of linear least square method and non-linear method for estimating the isotherm parameters was made using the experimental equilibrium data of safranin onto activated carbon at two different solution temperatures 305 and 313 K. Equilibrium data were fitted to Freundlich, Langmuir and Redlich-Peterson isotherm equations. All the three isotherm equations showed a better fit to the experimental equilibrium data. The results showed that non-linear method could be a better way to obtain the isotherm parameters. Redlich-Peterson isotherm is a special case of Langmuir isotherm when the Redlich-Peterson isotherm constant g was unity.

  16. Analysis of water sorption isotherms of amorphous food materials by solution thermodynamics with relevance to glass transition: evaluation of plasticizing effect of water by the thermodynamic parameters.

    Science.gov (United States)

    Shimazaki, Eriko; Tashiro, Akiko; Kumagai, Hitomi; Kumagai, Hitoshi

    2017-04-01

    Relation between the thermodynamic parameters obtained from water sorption isotherms and the degree of reduction in the glass transition temperature (Tg), accompanied by water sorption, was quantitatively studied. Two well-known glassy food materials namely, wheat gluten and maltodextrin were used as samples. The difference between the chemical potential of water in a solution and that of pure water ([Formula: see text]), the difference between the chemical potential of solid in a solution and that of a pure solid ([Formula: see text]), and the change in the integral Gibbs free energy ([Formula: see text]) were obtained by analyzing the water sorption isotherms using solution thermodynamics. The parameter [Formula: see text] correlated well with ΔTg (≡Tg - Tg0; where Tg0 is the glass transition temperature of dry material), which had been taken to be an index of plasticizing effect. This indicates that plasticizing effect of water on foods can be evaluated through the parameter [Formula: see text].

  17. Development and characterization of an edible composite film based on chitosan and virgin coconut oil with improved moisture sorption properties.

    Science.gov (United States)

    Binsi, P K; Ravishankar, C N; Srinivasa Gopal, T K

    2013-04-01

    An edible composite film was prepared from an emulsion system based on chitosan and virgin coconut oil (VCO). The effect of incorporation of VCO was evaluated at various concentrations and the optimum concentration was chosen based on resultant changes in the properties of the film. Addition of VCO in film forming solution resulted in increase in film thickness and marginal reduction in film transparency. Compatibility of VCO with chitosan was better at lower concentration of VCO as indicated by the microstructure of composite film in scanning electron micrographs. Phase separation was evident at higher level of oil incorporation and the optimal oil/chitosan ratio was determined to be at 0.5 to 1 mL/g chitosan. Furthermore, chemical interaction took place between VCO and chitosan as revealed by Fourier transform infrared spectroscopy data. Even though control chitosan films exhibited superior gas barrier properties, composite film with optimum VCO concentration revealed better mechanical and moisture sorption properties.

  18. Quantifying Time Dependent Moisture Storage and Transport Properties

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut H

    2003-01-01

    This paper describes an experimental and numerical approach to quantify the time dependence of sorption mechanisms for some hygroscopic building - mostly insulation - materials. Some investigations of retarded sorption and non-Fickian phenomena, mostly on wood, have given inspiration to the present...... analysis on these other materials. The true moisture capacity of a material can not be described by the slope of the sorption isotherms alone, when the material is exposed to dynamic changes in the moisture conditions. Still, the assumption of an immediate equilibrium is well accepted in the simulation...

  19. Physical stability and moisture sorption of aqueous chitosan-amylose starch films plasticized with polyols

    DEFF Research Database (Denmark)

    Cervera, Mirna Fernández; Karjalainen, Milja; Airaksinen, Sari

    2004-01-01

    The short-term stability and the water sorption of films prepared from binary mixtures of chitosan and native amylose maize starch (Hylon VII) were evaluated using free films. The aqueous polymer solutions of the free films contained 2% (w/w) film formers, glycerol, or erythritol as a plasticizer...... in the crystallinity of the films are evident within a 3-month period of storage, and the changes in the solid state are dependent on the plasticizer and storage conditions. When stored at ambient conditions for 3 months, the aqueous chitosan-amylose starch films plasticized with erythritol exhibited a partly...

  20. THE VIBRATIONAL PROPERTIES OF CHINESE FIR WOOD DURING MOISTURE SORPTION PROCESS

    Directory of Open Access Journals (Sweden)

    Jiali Jiang,

    2012-06-01

    Full Text Available The vibrational properties of Chinese fir (Cunninghamia lanceolata wood were investigated in this study as a function of changes in moisture content (MC and grain direction. The dynamic modulus of elasticity (DMOE and logarithmic decrement (δ were examined using a cantilever beam vibration testing apparatus. It was observed that DMOE and δ of wood varied widely during moisture adsorption and desorption. The DMOE of wood conditioned by the adsorption process showed significant increases during the later stages of conditioning when the MC scarcely changed. However, with the desorption process, the DMOE did not increase as much during the later stages of conditioning, though they increased during the early stages of conditioning when the MC greatly decreased. These results suggest that wood in an unstable state, caused via the existing state of moisture, shows different vibrational behaviors. Furthermore, the parallel to grain direction showed much higher DMOE and lower δ when compared to the perpendicular to grain direction. The variation of vibrational properties between parallel and perpendicular to grain direction under constant MC and during moisture adsorption process could be attributed due to the microscopic, macroscopic molecular, as well as chemical constituents of wood.

  1. Water absorption of freeze-dried meat at different water activities: a multianalytical approach using sorption isotherm, differential scanning calorimetry, and nuclear magnetic resonance.

    Science.gov (United States)

    Venturi, Luca; Rocculi, Pietro; Cavani, Claudio; Placucci, Giuseppe; Dalla Rosa, Marco; Cremonini, Mauro A

    2007-12-26

    Hydration of freeze-dried chicken breast meat was followed in the water activity range of aw=0.12-0.99 by a multianalytical approach comprising of sorption isotherm, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). The amount of frozen water and the shape of the T2-relaxogram were evaluated at each water content by DSC and NMR, respectively. Data revealed an agreement between sorption isotherm and DSC experiments about the onset of bulk water (aw=0.83-0.86), and NMR detected mobile water starting at aw=0.75. The origin of the short-transverse relaxation time part of the meat NMR signal was also reinvestigated through deuteration experiments and proposed to arise from protons belonging to plasticized matrix structures. It is proved both by D2O experiments and by gravimetry that the extra protons not contributing to the water content in the NMR experiments are about 6.4% of the total proton NMR CPMG signal of meat.

  2. Capillary condensation, freezing, and melting in silica nanopores: A sorption isotherm and scanning calorimetry study on nitrogen in mesoporous SBA-15

    Science.gov (United States)

    Moerz, Sebastian T.; Knorr, Klaus; Huber, Patrick

    2012-02-01

    Condensation, melting, and freezing of nitrogen in a powder of mesoporous silica grains (SBA-15) has been studied by combined volumetric sorption isotherm and scanning calorimetry measurements. Within the mean-field model of Saam and Cole for vapor condensation in cylindrical pores, a liquid nitrogen sorption isotherm is well described by a bimodal pore radius distribution. It encompasses a narrow peak centered at 3.3 nm, typical of tubular mesopores, and a significantly broader peak characteristic of micropores, located at 1 nm. The material condensed in the micropores as well as the first two adsorbed monolayers in the mesopores do not exhibit any caloric anomaly. The solidification and melting transformation affects only the pore condensate beyond approximately the second monolayer of the mesopores. Here, interfacial melting leads to a single peak in the specific-heat measurements. Homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the mesopores result in a caloric freezing anomaly similarly complex and dependent on the thermal history to that observed for argon in SBA-15. The axial propagation of the crystallization in pore space is more effective in the case of nitrogen than previously observed for argon, which we attribute to differences in the crystalline textures of the pore solids.

  3. Non-equilibrium and equilibrium sorption with a linear-sorption isotherm during mass transport through an infinite, porous medium: some analytical solutions

    Energy Technology Data Exchange (ETDEWEB)

    Carnahan, C.L.; Remer, J.S.

    1981-04-01

    Analytical solutions have been developed for the problem of solute transport in a steady, three dimensional field of groundwater flow with non-equilibrium mass transfer of a radioactive species between fluid and solid phases and with anisotropic hydrodynamic dispersion. Interphase mass transport is described by a linear rate expression. Solutions are presented also for the case of equilibrium distribution of solute between fluid and solid phases. Three types of release from a point source were considered: instantaneous release of a finite mass of solute, continuous release at an exponentially decaying rate, and release for a finite period of time. Graphical displays of computational results for point-source solutions show the expected variation of sorptive retardation effects progressing from the case of no sorption, through several cases of non-equilibrium sorption, to the case of equilibrium sorption. The point-source solutions can be integrated over finite regions of a space to provide analytical solutions for regions of solute release having finite spatial extents and various geometrical shapes, thus considerably extending the utility of the point-source solutions.

  4. Sorption Properties of Some Romanian Gingerbread

    Directory of Open Access Journals (Sweden)

    Tulbure Anca

    2014-06-01

    Full Text Available Water activity of gingerbread is very important for keeping the product freshness and shelf life. Water activity is influenced by composition, water content and temperature. The water content of gingerbread could vary according with storage condition. i.e. rH. 11 gingerbread samples were analysed. The water content and water activity lies between 7.0 and 12.6% and respectively 0.590 and 0.715. The sorption isotherms were determined at 30°C by gravimetric method. The moisture sorption is influenced by composition, especially sweeteners and humectants. Honey and invert sugar have the same impact on gingerbread higroscopicity.

  5. Isosteric Vapor Pressure – Temperature Data for Water Sorption in Hardened Cement Paste: Enthalpy, Entropy and Sorption Isotherms at Different Temperatures

    DEFF Research Database (Denmark)

    Radjy, Fariborz; Sellevold, Erik J.; Hansen, Kurt Kielsgaard

    . The accuracies for pressure, enthalpy and entropy are found to be 0.5% or less. PART II: The TPA-system has been used to generate water vapor pressure – temperature data for room temperature – and steam cured hardened cement pastes as well as porous vycor glass. The moisture contents range from saturated to dry...

  6. "Multi-temperature" method for high-pressure sorption measurements on moist shales.

    Science.gov (United States)

    Gasparik, Matus; Ghanizadeh, Amin; Gensterblum, Yves; Krooss, Bernhard M

    2013-08-01

    A simple and effective experimental approach has been developed and tested to study the temperature dependence of high-pressure methane sorption in moist organic-rich shales. This method, denoted as "multi-temperature" (short "multi-T") method, enables measuring multiple isotherms at varying temperatures in a single run. The measurement of individual sorption isotherms at different temperatures takes place in a closed system ensuring that the moisture content remains constant. The multi-T method was successfully tested for methane sorption on an organic-rich shale sample. Excess sorption isotherms for methane were measured at pressures of up to 25 MPa and at temperatures of 318.1 K, 338.1 K, and 348.1 K on dry and moisture-equilibrated samples. The measured isotherms were parameterized with a 3-parameter Langmuir-based excess sorption function, from which thermodynamic sorption parameters (enthalpy and entropy of adsorption) were obtained. Using these, we show that by taking explicitly into account water vapor as molecular species in the gas phase with temperature-dependent water vapor pressure during the experiment, more meaningful results are obtained with respect to thermodynamical considerations. The proposed method can be applied to any adsorbent system (coals, shales, industrial adsorbents) and any supercritical gas (e.g., CH4, CO2) and is particularly suitable for sorption measurements using the manometric (volumetric) method.

  7. ``Multi-temperature'' method for high-pressure sorption measurements on moist shales

    Science.gov (United States)

    Gasparik, Matus; Ghanizadeh, Amin; Gensterblum, Yves; Krooss, Bernhard M.

    2013-08-01

    A simple and effective experimental approach has been developed and tested to study the temperature dependence of high-pressure methane sorption in moist organic-rich shales. This method, denoted as "multi-temperature" (short "multi-T") method, enables measuring multiple isotherms at varying temperatures in a single run. The measurement of individual sorption isotherms at different temperatures takes place in a closed system ensuring that the moisture content remains constant. The multi-T method was successfully tested for methane sorption on an organic-rich shale sample. Excess sorption isotherms for methane were measured at pressures of up to 25 MPa and at temperatures of 318.1 K, 338.1 K, and 348.1 K on dry and moisture-equilibrated samples. The measured isotherms were parameterized with a 3-parameter Langmuir-based excess sorption function, from which thermodynamic sorption parameters (enthalpy and entropy of adsorption) were obtained. Using these, we show that by taking explicitly into account water vapor as molecular species in the gas phase with temperature-dependent water vapor pressure during the experiment, more meaningful results are obtained with respect to thermodynamical considerations. The proposed method can be applied to any adsorbent system (coals, shales, industrial adsorbents) and any supercritical gas (e.g., CH4, CO2) and is particularly suitable for sorption measurements using the manometric (volumetric) method.

  8. Mold appearance and modeling on selected corn stover components during moisture sorption.

    Science.gov (United States)

    Igathinathane, C; Womac, A R; Pordesimo, L O; Sokhansanj, S

    2008-09-01

    Occurrence of mold was visually monitored for 26days on samples of major anatomical components of corn stover maintained at several storage temperatures (T) and water activities (a(w)). Glass desiccators with saturated salt solutions placed in temperature controlled chambers provided simulated storage conditions with temperatures ranging from 10 degrees C to 40 degrees C and water activities ranging from 0.11 to 0.98. Mold affected leaf, stalk skin, and stalk pith equally at water activity greater than 0.9. As expected, a combination of increased water activity greater than 0.9 and temperatures greater than 30 degrees C was conducive to mold growth. Based on material moisture content during the initial mold growth, it was postulated that among the corn stover components the stalk pith was the least resistant to mold growth followed by stalk skin and leaf for the studied range of temperature and water activity. Mold growth models fitted well with the observation. A linear mold-free days predictions using a three-parameter regression model (T, a(w), and T x a(w)) was superior (R(2)=0.99) to other models considered. The exponential spoilage model using two parameter T and a(w) also gave comparable performance (R(2)=0.95). Among the independent factors, T x a(w) product was the most significant (p=0.0069) followed by T (p=0.0114), and a(w) (p=0.3140) in explaining the experimental data. The developed models can be applied to predict the safe storage period of corn stover components exposed to various temperature and moisture environmental conditions.

  9. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal

    2012-11-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  10. Isosteric Vapor Pressure – Temperature Data for Water Sorption in Hardened Cement Paste: Enthalpy, Entropy and Sorption Isotherms at Different Temperatures

    DEFF Research Database (Denmark)

    Radjy, Fariborz; Sellevold, Erik J.; Hansen, Kurt Kielsgaard

    and the temperatures range from 2 to 95 °C, differing for the specimen types. The data has been analyzed to yield differential enthalpy and entropy of adsorption, as well as the dependence of the relative vapor pressure on temperature at various constant moisture contents. The implications for the coefficient......PART I: In order to generate isosteric (constant mass) vapor pressure – temperature data (P-T data) for adsorbed pore water in hydrated cement paste, the Thermo Piestic Analysis system (the TPA system) described herein was developed. The TPA system generates high precision equilibrium isosteric P....... The accuracies for pressure, enthalpy and entropy are found to be 0.5% or less. PART II: The TPA-system has been used to generate water vapor pressure – temperature data for room temperature – and steam cured hardened cement pastes as well as porous vycor glass. The moisture contents range from saturated to dry...

  11. Modeling of water transport in roof tiles by removal of moisture at isothermal conditions

    Science.gov (United States)

    da Silva, Wilton Pereira; de Oliveira Farias, Vera Solange; de Araújo Neves, Gelmires; de Lima, Antonio Gilson Barbosa

    2012-05-01

    The main objective of this article is to describe the drying process of ceramic roof tiles, shaped from red clay, using diffusion models. Samples of the product with initial moisture content of 0.24 (db) were placed inside an oven in the temperatures of 55.6, 69.7, 82.7 and 98.6°C; and the data of the drying kinetics were obtained. The analytical solutions of the diffusion equation for the parallelepiped with boundary conditions of the first and third kinds were used to describe the drying processes. The process parameters were determined using an optimization algorithm based on inverse method coupled to the analytical solutions. The analysis of the results makes it possible to affirm that the boundary condition of the third kind satisfactorily describes the drying processes. The values obtained for the convective mass transfer coefficient were between 8.25 × 10-7 and 1.64 × 10-6 m s-1, and for the effective water diffusivity were between 9.21 × 10-9 and 1.80 × 10-8 m2 s-1.

  12. Sorption isotherm studies of Cd(II) ions using living cells of the marine microalga Tetraselmis suecica (Kylin) Butch.

    Science.gov (United States)

    Pérez-Rama, M; Torres, E; Suárez, C; Herrero, C; Abalde, J

    2010-10-01

    The present work reports the use of living cells of the marine microalga Tetraselmis suecica for the biosorption of cadmium ions. For a better understanding of the biosorption characteristics, three fractions of removed cadmium (total, bioadsorbed and intracellular) were measured in the cells after 24 and 72 h of exposure to different initial cadmium concentrations (0.6-45 mg L(-1)). Both the Langmuir and Freundlich models were suitable for describing the sorption of cadmium ions by this microalga. The maximum sorption capacity was estimated to be 40.22 mg Cd g(-1) after 72 h using the Langmuir sorption model. In the lower cadmium concentrations, metal removed intracellularly was higher than that removed on the microalgal cell surface. Therefore, the intracellular fraction contributed more to the total removed cadmium than the fraction bioadsorbed to the cellular surface. The results showed that the cadmium removal capacity using living biomass could be much more effective than with non-living biomass due to the intracellular bioaccumulation. According to the microorganism selected and its tolerance to the toxic effect of the metal, the cadmium content in the intracellular fraction can become very significant, just like it happened with Tetraselmis.

  13. Quantification of low levels (<10%) of amorphous content in micronised active batches using dynamic vapour sorption and isothermal microcalorimetry.

    Science.gov (United States)

    Mackin, Lesley; Zanon, Roger; Park, Jung Min; Foster, Kimberly; Opalenik, Holly; Demonte, Matt

    2002-01-14

    During the processing of pharmaceutical solids (e.g. milling, spray drying, tablet compaction, wet granulation and lyophilisation), various degrees of disorder in the form of crystal defects and/or amorphous regions may be generated. Even relatively low levels of amorphous material (developed at a very early stage of the actives development program such that the impact of small quantities of amorphous material on the quality attributes of the formulation can be fully assessed. The methods can be applied to any active, the only criteria is that the amorphous material will recrystallise on exposure to moisture or solvent vapours, and no hydrates or solvates are formed.

  14. Water sorption properties of Dutch type semi-hard cheese edge in the range of common storing temperatures

    Directory of Open Access Journals (Sweden)

    Maria Carolina Soares Pereira

    2011-01-01

    Full Text Available Moisture sorption isotherms of Dutch type semi-hard cheese edge in the temperature range of 10–25 ºC and water activity (Aw from 0.11 to 0.98 were determined using manometric method. The sorption curves had a sigmoid shape. The equilibrium moisture content (EMC of cheese samples increased with an increase in Aw at a constant temperature both for water adsorption and desorption. An increase in temperature caused an increase in Aw for the same moisture content (MC and, if Aw was kept constant, an increase in temperature caused a decrease in the amount of absorbed water. Critical values of equilibrium moisture content, corresponding to the Aw = 0.6, were between 11 % MC (w.b. and 17 % MC (w.b. both for moisture adsorption and desorption. Values of sorption heat were calculated from moisture sorption isotherms by applying the Clausius-Clapeyron equation. Values of the heat of desorption are higher than those of adsorption and the difference increases with the MC decrease. Heat of sorption decreased from 48.5 kJ/mol (~5.5 % MC w.b. to the values approaching the heat of vaporization of pure water, free MC. The critical value for free water evaporation is about w = 27 % (w.b. for the range of temperature 10–25 ºC.

  15. Study of adsorption isotherms of green coconut pulp

    Directory of Open Access Journals (Sweden)

    Fábia Carolina Gonçalves Lavoyer

    2013-03-01

    Full Text Available Brazil is considered one of the largest producers and consumers of tropical fruits. Green coconut (Cocos nucifera L. stands out not only for its production and consumption, but also for the high amount of waste produced by coconut water industry and in natura consumption. Therefore, there is a need for utilization of this by-product. This study aims to study the adsorption isotherms of green coconut pulp and determine its isosteric heat of sorption. The adsorption isotherms at temperatures of 30, 40, 50, 60, and 70 °C were analyzed, and they exhibit type III behavior, typical of sugar rich foods. The experimental results of equilibrium moisture content were correlated by models present in the literature. The Guggenheim, Anderson and De Boer (GAB model proved particularly good overall agreement with the experimental data. The heat of sorption determined from the adsorption isotherms increased with the decrease in moisture content. The heat of sorption is considered as indicative of intermolecular attractive forces between the sorption sites and water vapor, which is an important factor to predict the shelf life of dried products.

  16. Analysis of the effects of the heat of sorption on the process of heat transfer in moisture exchange across a membrane

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A theoretical study has been conducted to investigate the effects of mass transfer on heat transfer in moisture exchange across a membrane and a mathematical model describing the heat transfer process with consideration of the heat of sorption was established.A dimensionless variable,Ψ =JLλ /δ(T10-T20),which controls the effect of the heat of sorption on the heat transfer in membrane process,was obtained through theoretical analysis,and the effects of Ψ on the heat transfer process were analyzed.Results showed that in the case that the temperature gradient and mass transfer are in the same direction,the effective heat flux changes the direction at Ψ =1.For Ψ <1,the heat transfers from high to low temperature sides through the membrane,and the total thermal resistance increases with increasing the moisture flux across membrane or reducing the temperature difference between the bulk flows on the two sides of membrane.For Ψ >1,the overall effect of the heat and mass transfer is that the effective heat flux points from low to high temperature sides and the total thermal resistance decreases with increasing the mass flux or reducing the temperature difference.In the case that the tem-perature gradient and mass transfer are in the opposite directions,the existence of the heat of sorption acts to enhance the heat transfer from high to low temperature sides,causing a reduced total thermal resistance,and the greater the mass flux or the smaller the temperature difference,the smaller the total thermal resistance.

  17. Sorption Isotherms and Sorption Thermodynamics of Faecal Sterols on Offshore Sediment%近海沉积物对粪固醇的等温吸附和热力学研究

    Institute of Scientific and Technical Information of China (English)

    张晓蕾; 薛文平; 徐恒振; 马新东

    2012-01-01

    Experiments of faecal sterols adsorption from aqueous solutions onto Dalian offshore sediment were done by a batch equilibrium method,and the sorption of 12 kinds of faecal sterols in sediment were investigated in this paper.It was shown that the adsorption equilibrium time was 24 h,and after 24 h the variation tendency of 5 kinds of fingerprint values was stable.It indicated that adsorption isothermal data was interpreted by the Henry,Freundlich,Langmuir,Duhinin-Radushkevich(D-R) and Temkin equations,and demonstrated that the other 4 isotherms provided stronger data fitting than the Langumir isotherm.It inferred that from D-R model the mean free energy of adsorption process of 12 kinds of faecal sterols was from 7 071.1 J·mol-1 to 9 128.7 J·mol-1,and concluded that it was mainly physical adsorption of the sorptive process of 12 kinds of faecal sterols in sediment.It discovered that from the Temkin model the value of Kfof cholestanone was the maximum,and extrapolated that cholestanone was adsorbed most easily on sediment.It stated that the enthalpy and entropy change of the adsorption were both less than zero,and inferred that the adsorption process was exothermic and spontaneous.%采用大连湾近海表层沉积物为吸附剂,粪固醇为吸附质,通过批量平衡法,研究了近海沉积物对12种粪固醇的吸附行为.结果表明,12种粪固醇在24 h吸附达到平衡后,5种粪固醇的指纹值变化趋于稳定;用Henry、Freundlich、Langumir、Dubinin-Radushkevich(D-R模型)、Temkin这5种等温吸附模型来拟合,其中Langumir模型不适合拟合沉积物对粪固醇的吸附数据,其他4种模型均能较好地拟合.D-R模型拟合效果表明,12种粪固醇的吸附平均自由能在7 071.1~9 128.7 J.mol-1之间,12种粪固醇的吸附过程主要是物理吸附的作用.Temkin模型拟合效果表明,加氢胆固酮(Kf=8.89×106)的Kf值最大,说明沉积物吸附加氢胆固酮之间的作用最大,加氢胆固酮

  18. Using the internal stress concept to assess the importance of moisture sorption-induced swelling on the moisture transport through the glassy HPMC films

    NARCIS (Netherlands)

    Laksmana, Fesia L.; Kok, Paul J.A. Hartman; Frijlink, Henderik W.; Vromans, Herman; Van der Voort Maarschalk, Kees

    2008-01-01

    The purpose of this research was to elucidate the significance of the changes in the mechanical and the volumetric properties on the moisture diffusivity through the polymer films. The internal stress concept was adapted and applied to estimate the relative impact of these property changes on the to

  19. Analysis of the effects of the heat of sorption on the process of heat transfer in moisture exchange across a membrane

    Institute of Scientific and Technical Information of China (English)

    HU Teng; MIN JingChun; SONG YaoZu

    2008-01-01

    A theoretical study has been conducted to investigate the effects of mass transfer on heat transfer in moisture exchange across a membrane and a mathematical model describing the heat transfer process with consideration of the heat of sorp-tion was established. A dimensionless variable, ψ=JLλ|δ(T10-T20), which controls the effect of the heat of sorpllon on the heat transfer in membrane process, was obtained through theoretical analysis, and the effects of ψon the heat transfer process were analyzed. Results showed that in the case that the temperature gra-dient and mass transfer are in the same direction, the effective heat flux changes the direction at ψ=1. For ψ1, the overall effect of the heat and mass transfer is that the effective heat flux points from low to high temperature sides and the total thermal resistance decreases with increasing the mass flux or reducing the temperature difference. In the case that the tem-perature gradient and mass transfer are in the opposite directions, the existence of the heat of sorption acts to enhance the heat transfer from high to low temperature sides, causing a reduced total thermal resistance, and the greater the mass flux or the smaller the temperature difference, the smaller the total thermal resistance.

  20. Isotermas de sorção de tâmaras: determinação experimental e avaliação de modelos matemáticos Dates sorption isotherms: experimental determination and mathematics models evaluation

    Directory of Open Access Journals (Sweden)

    Mônica E.T. PRADO

    1999-01-01

    Full Text Available As isotermas de sorção de tâmaras (Phoenix dactylifera L., da variedade Zahidi, foram determinadas para três temperaturas, 60, 70 e 80° C pelo método estático gravimétrico. As curvas experimentais foram ajustadas pelas equações de BET, BET linearizada, GAB, HALSEY, OSWIN e PELEG. O desvio relativo entre os valores experimentais e os valores estimados foi calculado para cada curva, a fim de se avaliar qual equação melhor se ajustou aos dados experimentais.Dates sorption isotherms were determined by gravimetric at three differents temperatures (60, 70 and 80° C. Experimental data was adjusted to six sorption models de BET, linear BET, GAB, HALSEY, OSWIN and PELEG. The average relative deviations between calculated and experimental data were calculated do select best fit model.

  1. Non-isothermal moisture balance equation in porous media: a review of mathematical formulations in Building Physics

    Directory of Open Access Journals (Sweden)

    Dubois, S.

    2014-01-01

    Full Text Available Understanding heat and mass transfers in porous materials is crucial in many areas of scientific research. Mathematical models have constantly evolved, their differences lying mainly in the choice of the driving potentials used to describe moisture flows, as well as in the complexity of characterizing the physical phenomena involved. Models developed in the field of Building Physics (HAM models are used to describe the behavior of envelope parts and assess their impact on user comfort and energy performance. The water balance equation can be described in many ways; it is a function of the boundary conditions considered and the fact they induce high or low water content in the porous materials used. This paper gives an overview of various formulations for this equation that are found in the Building Physics literature. It focuses first on the physically based formulation of moisture balance, drawing on the Representative Elementary Volume (REV concept, coupled with thermodynamic flow rates description. This is then reformulated in line with various main moisture state variables offering a wide variety of expressions that are compared with available models. This approach provides access to all secondary transport coefficients associated with the process of mathematical transformation. Particular emphasis is placed on the moisture storage function choice and its impact on the final mathematical formulations.

  2. Effect of drying method on the adsorption isotherms and isosteric heat of passion fruit pulp powder

    Directory of Open Access Journals (Sweden)

    Maria Angélica Marques Pedro

    2010-12-01

    Full Text Available The sorption behavior of dry products is generally affected by the drying method. The sorption isotherms are useful to determine and compare thermodynamic properties of passion fruit pulp powder processed by different drying methods. The objective of this study is to analyze the effects of different drying methods on the sorption properties of passion fruit pulp powder. Passion fruit pulp powder was dehydrated using different dryers: vacuum, spray dryer, vibro-fluidized, and freeze dryer. The moisture equilibrium data of Passion Fruit Pulp (PFP powders with 55% of maltodextrin (MD were determined at 20, 30, 40 and 50 ºC. The behavior of the curves was type III, according to Brunauer's classification, and the GAB model was fitted to the experimental equilibrium data. The equilibrium moisture contents of the samples were little affected by temperature variation. The spray dryer provides a dry product with higher adsorption capacity than that of the other methods. The vibro-fluidized bed drying showed higher adsorption capacity than that of vacuum and freeze drying. The vacuum and freeze drying presented the same adsorption capacity. The isosteric heats of sorption were found to decrease with increasing moisture content. Considering the effect of drying methods, the highest isosteric heat of sorption was observed for powders produced by spray drying, whereas powders obtained by vacuum and freeze drying showed the lowest isosteric heats of sorption.

  3. Humidity sorption on natural building stone

    Science.gov (United States)

    Franzen, C.; Mirwald, P.

    2003-04-01

    processes, physical, chemical or biological, depend on the presence of water. Like most porous materials building stone respond on humidity by water uptake. The sorption isotherm represents the equilibrium moisture, specific for each material. The determination of the isotherm for stone of low and small porosity like marble is difficult. With the help of a newly developed water sorption analysis chamber [2], which allows the simultaneous measurement of 11 samples, good results on stone/rock samples have been obtained. Even at marble species with pore volumes lower than 0.4 % isotherms are measured. This analytical method offers new insights in the pore behaviour of low porosity materials. The advantages of this technique which supplements other techniques (e.g. BET, Hg-porosimetry) are: i) the testing agent is identical to the weathering agent, water; ii) the atmospheric parameters at the measurement reflect the natural conditions - thus no changes to the material properties have to be considered; iii) due to the small diameter of the water molecule (~0.28 nm), smaller pores are reached than e.g. with N2 (~0.31 nm). Sorption isotherms of sandstone (Baumberg, Obernkirchen, Groeden), granite (Brixen), and marble (Sterzing, Laas) are presented. Particular as to marbles the resolution is considerably higher. A previously observed negative hysteresis [3] seems an effect due to limited data resolution. [1] Snethlage, R. (1984) Steinkonservierung, Bayer. LA Denkmalpflege, Ah. 22, 203 S. [2] Griesser, U.J., Dillenz, J. (2002) Neuartiges, vollautomatisches Feuchtesorptionsprüfgerät mit hohem Probendurchsatz, Feuchtetag 2002, Weimar, 85-93. [3] Fimmel, R. (1996) Verwitterungsverhalten der alpinen Marmore von Laas und Sterzing, Diss. Univ. Ibk, 116 S.

  4. A Hysteresis Model Suitable For Numerical Simulation Of Moisture Content in Wood

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan; Damkilde, Lars

    2007-01-01

    The equilibrium moisture content in wood depends not only on the current relative humidity in the ambient air but also on the history of the relative humidity variations. This hysteresis dependency of sorption in wood implies that in the worst case the moisture content for a given relative humidi...... temperatures. These features make the model relatively easy to implement into a numerical method, e.g. the Finite Element Method....... may deviate by 30-35%. While researchers seem to have reached a general agreement on the hypothesis for the sorption hysteresis phenomenon, only a few models describing the phenomenon are available. Current models as the independent domain model have numerical deficiencies and drawbacks. This paper...... presents a new hysteresis model, which mathematically resolves in closed form expressions, with the current relative humidity and moisture content as the only input parameters. Furthermore, the model has the advantage of being applicable to different sorption isotherms, i.e. different species and different...

  5. An enhanced beam model for glued laminated structures that takes moisture, mechano-sorption and time effects into account

    DEFF Research Database (Denmark)

    Ormarsson, Sigurdur; Steinnes, Jan Roar

    2014-01-01

    There is a need of more advanced analysis for studying how the long-term behaviour of glued laminated timber structures is affected by creep and by cyclic variations in climate. A beam theory is presented able to simulate the overall hygro-mechanical and visco-elastic behaviour of (inhomogeneous)...... that occurs to have a significant effect on deformations, section forces and stress distributions within the frame structures that were studied.......) glulam structures. Two frame structures subjected to both mechanical and cyclic environmental loading are analysed to illustrate the advantages the model involved can provide. The results indicate clearly both the (discontinuous) inhomogeneity of the glulam products and the variable moisture-load action...

  6. Water adsorption isotherms and isosteric sorption heat of spray-dried and freeze-dried dehydrated passion fruit pulp with additives and skimmed milk Isotermas de adsorção e calor isostérico de sorção de polpa de maracujá desidratada por spray dryer e liofilizador com aditivos e leite desnatado

    Directory of Open Access Journals (Sweden)

    Kelly Tafari Catelam

    2011-12-01

    Full Text Available Moisture equilibrium data of passion fruit pulp powders with maltodextrin and gum arabic were obtained by two different drying methods (spray drying and freeze drying and determined at 20, 30, 40 and 50º C. Skimmed milk was used to substitute part of these additives in the samples. One formulation using passion fruit pulp/maltodextrin/skimmed milk (PMS was prepared, and another using passion fruit pulp/gum arabic/skimmed milk (PGS. The behavior of curves was type III, according to Brunauer's classification. GAB models were fitted to experimental equilibrium data. The parameters obtained from GAB models was affected by the presence of additives. The behavior of the sorption isotherms for different temperatures are similar, noting only a small effect of temperature. There were little differences between both drying methods and additives used in relation to equilibrium moisture content. The parameters obtained with the addition of the skimmed milk were considered satisfactory (Xm values ranged from 0,04084 to 0,06488 in dry basis, demonstrating that it is an effective and cheap alternative for regular additives. A progressive increase in the heat of sorption in relation to decreasing moisture content was observed and the heat of sorption values of different samples are all similar, comparing the relative equilibrium moisture content.Dados de umidade de equilíbrio da polpa de maracujá em pó com maltodextrina e goma arábica obtidas por dois diferentes processos de secagem (spray dryer e liofilizador foram determinados a 20, 30, 40 e 50° C. Leite desnatado foi utilizado nas amostras em substituição a uma parte desses dois aditivos. Prepararou-se uma formulação, usando polpa de maracujá/maltodextrina/leite desnatado (PMS e outra com polpa de maracujá/goma arábica/leite desnatado (PGS. Os comportamentos das isotermas obedeceram ao tipo III, de acordo com a classificação de Brunauer e utilizou-se o modelo de GAB para ajuste dos dados de

  7. Thermodynamic study on dynamic water vapor sorption in Sylgard-184.

    Science.gov (United States)

    Harley, Stephen J; Glascoe, Elizabeth A; Maxwell, Robert S

    2012-12-01

    The dynamic and equilibrium water vapor sorption properties of Sylgard-184, a commercially available poly(dimethylsiloxane) elastomer (PDMS), were determined via gravimetric analysis from 30 to 70 °C. Described here is a methodology for quantitatively assessing how water vapor diffuses and ad/absorbs into polymeric materials that are traditionally considered hydrophobic. PDMS materials are frequently chosen for their moisture barrier properties; our results, however, demonstrate that moisture is able to penetrate the material over a range of temperatures and humidities. The sorption values measured here ranged from ca. 0.1 to 1.4 cm(3) (STP) H(2)O/g Sylgard. The isotherms exhibited sigmoidal character and were fit to a triple mode sorption model. Asymptotic behavior at low water activities was characterized using a Langmuir type adsorption model, linear behavior was fit to a Henry's law type dependence, and the convex portion at higher activities was fit with good agreement to Park's equation for pooling or clustering. The thermal dependence of these sorption modes was also explored and reported. The dynamics of the sorption process were fit to a Fickian model and effective diffusivities are reported along with corresponding activation energies. The diffusivity values measured here ranged from ca. 0.5 to 3.5 × 10(-5) cm(2)/s depending on the temperature and relative humidity. The concentration dependence of the diffusivity showed a direct correlation with the three modes of uptake obtained from the isotherms. Corrections to the diffusivities were calculated using existing models that take into account adsorption and pooling.

  8. Kinetic modeling of water sorption by roasted and ground coffee

    Directory of Open Access Journals (Sweden)

    Fernanda Machado Baptestini

    2017-05-01

    Full Text Available The objective of this study was to model the kinetics of water sorption in roasted and ground coffee. Crude Arabica coffee beans with an initial moisture content of 0.1234 kgwkgdm-1 were used. These beans were roasted to a medium roast level (SCCA # 55 and ground at three particle sizes: coarse (1.19 mm, medium (0.84 mm and fine (0.59 mm. To obtain the water sorption isotherms and the isosteric heat, different conditions of temperature and relative humidity were analyzed using the dynamic method at 25ºC (0.50, 0.60, 0.70, and 0.80 of RH and 30°C (0.30, 0.40, 0.50, 0.60, 0.70, and 0.80 of RH and using the static method at 25ºC (0.332 and 0.438 of RH. The GAB model best represented the hygroscopic equilibrium of roasted coffee at every particle size. Isosteric heat of sorption for the fine particle size increased with increments of equilibrium moisture content, indicating a strong bond energy between water molecules and the product components. The Gibbs free energy decreased with the increase in equilibrium moisture content and with temperature.

  9. Isotermas de sorção de metais pesados em solos do cerrado de Goiás Sorption isotherm of heavy metals in soils of 'Cerrado' of Goiás

    Directory of Open Access Journals (Sweden)

    Luiz F. C. Oliveira

    2010-07-01

    Full Text Available A contaminação do solo e das águas subterrâneas por metais pesados é, extremamente perniciosa por serem basntante persistentes no ambiente. Objetivou-se, com este trabalho, a análise da sorção do Cu, Cr, Zn, Cd, Pb e Ni em Latossolo Vermelho Acriférrico (LVwf, Argissolo Vermelho Eutrófico (PVe, Nitossolo Vermelho Eutroférrico (NVef e Neossolo Quartzarênico (RQ pelos modelos potencial e linear da isoterma Freundlich. Para o estabelecimento de isotermas de sorção adicionaram-se a 5,0 mL de solo e 50,0 mL de solução contendo o metal pesado a ser avaliado com diferentes concentrações, respeitando-se os limites aceitáveis. As isotermas de sorção potencial e linear apresentaram bom ajuste para descrever o comportamento de adsorção dos metais pesados nas diferentes classes de solo estudadas. A sequência da retenção dos metais pesados em ordem decrescente, foi, para: o PVe: Cr+3 > Cr+6 > Ni+2 > Zn+2 > Cu+2 > Pb+2 > Cd+2; o LVwf: Cr+3 > Cr+6 > Ni+2 > Cu+2 > Cd+2 > Zn+2 > Pb+2; o RQ: Cr+6 > Cr+3 >Cu+2 > Pb+2 > Ni+2 > Zn+2 > Cd+2 e, para, o NVef: Cr+3 > Cr+6 > Pb+2 > Cu+2 > Zn+2 > Ni+2 >Cd+2. O RQ foi a classe de solo que apresentou menor retenção de metais em comparação com as demais classes de solo sendo, portanto, mais vulnerável à contaminação de águas subterrâneas.The contamination of soil and groundwater by heavy metals is extremely damaging due to high persistence of heavy metals in the environment. This work targeted the analysis of the sorption in Oxisol Typic Acrustox(LVwf, Ultisol (PVe, Kandic Oxisol (NVef and Quartzipsamment (RQ of heavy metals Cu, Cr, Zn, Cd, Pb and Ni. The sorption of the heavy metals in the soil was evaluated by batch method and described by potential and linear models of the Freundlich isotherm. For the establishment the of sorption isotherm, 50.0 mL of solution containing the heavy metal were added in 5.0 mL of soil, assessing with different concentrations within the acceptable soil

  10. Moisture diffusion and permeability characteristics of hydroxypropylmethylcellulose and hard gelatin capsules.

    Science.gov (United States)

    Barham, Ahmad S; Tewes, Frederic; Healy, Anne Marie

    2015-01-30

    The primary objective of this paper is to compare the sorption characteristics of hydroxypropylmethylcellulose (HPMC) and hard gelatin (HG) capsules and their ability to protect capsule contents. Moisture sorption and desorption isotherms for empty HPMC and HG capsules have been investigated using dynamic vapour sorption (DVS) at 25°C. All sorption studies were analysed using the Young-Nelson model equations which distinguishes three moisture sorption types: monolayer adsorption moisture, condensation and absorption. Water vapour diffusion coefficients (D), solubility (S) and permeability (P) parameters of the capsule shells were calculated. ANOVA was performed with the Tukey comparison test to analyse the effect of %RH and capsule type on S, P, and D parameters. The moisture uptake of HG capsules were higher than HPMC capsules at all %RH conditions studied. It was found that values of D and P across HPMC capsules were greater than for HG capsules at 0-40 %RH; whereas over the same %RH range S values were higher for HG than for HPMC capsules. S values decreased gradually as the %RH was increased up to 60% RH. To probe the effect of moisture ingress, spray dried lactose was loaded into capsules. Phase evolution was characterised by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and differential scanning calorimetry (DSC). The capsules under investigation are not capable of protecting spray dried lactose from induced solid state changes as a result of moisture uptake. For somewhat less moisture sensitive formulations, HPMC would appear to be a better choice than HG in terms of protection of moisture induced deterioration. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Sorption properties of modified potato starch

    Directory of Open Access Journals (Sweden)

    Teresa Witczak

    2016-12-01

    Full Text Available Background. Starch is one of the biopolymers most commonly used in the food industry. In its native form its applications are limited. In contrast, its structure is relatively readily modified using various methods, producing starch derivatives of greatly diverse properties. The primary methods used to change characteristics of starch include acetylation and oxidation. Thus obtained raw materials are used as food additives. Stability of these raw materials and food products to a considerable extent depends on their composition and parameters characterizing storage facilities, i.e. relative humidity and temperature. One of the methods to specify adequate ambient conditions is based on water activity supplemented by sorption isotherms. As a result studies investigating correlations between water activity and moisture content are of importance for the optimization of storage conditions and design of certain food processing procedures. For this reason the aim of this study was to assess the effect of modification (oxidation, acetylation and their combination on sorption properties (described based on sorption isotherms of potato starch. Material and methods. Analyses were conducted on potato starch and its derivatives produced by acetylation, oxidation and co-modification (acetylation coupled with oxidation. Starch was oxidized using sodium chlorate (I, while acetylation was run using anhydrous acetic acid. Sorption isotherms were determined by the static desiccator method. Results were described applying selected mathematical methods equipped with physical interpretations (BET and GAB and empirical models (Halsey, Oswin, Henderson, Pelega, Lewicki, Blahovec-Yanniotis. Calculations were made using non-linear estimation. Results. The greatest water absorbability was found for native potato starch. Modifications caused a decrease in the amount of adsorbed water vapour, dependent on the applied modification. Acetylation resulted in significantly

  12. Moisture transport in coated wood

    NARCIS (Netherlands)

    Meel, P.A. van; Erich, S.J.F.; Huinink, H.P.; Kopinga, K.; Jong, J. DE; Adan, O.C.G.

    2011-01-01

    Moisture accumulation inside wood causes favorable conditions for decay. Application of a coating alters the moisture sorption of wood and prevents accumulation of moisture. This paper presents the results of a nuclear magnetic resonance (NMR) study on the influence of a coating on the moisture abso

  13. Water sorption properties of HM-pectin and liposomes intended to alleviate dry mouth.

    Science.gov (United States)

    Adamczak, Małgorzata I; Martinsen, Ørjan G; Smistad, Gro; Hiorth, Marianne

    2016-06-15

    Pharmaceutical formulations intended for treatment of xerostomia (dry mouth) should be able to keep the oral mucosa hydrated for a prolonged period of time. The products already existing on the market contain water-soluble polymers, however their ability to moisturize the oral mucosa for a longer period of time seems limited. In this paper the sorption properties of water vapor of high-methoxylated pectin (HM-pectin, a hydrophilic biopolymer) and phosphatidylcholine-based (Soya-PC) liposomes have been studied and compared using a gravimetric method. The kinetics of water desorption and sorption have been recorded over the relative humidity range RH=95-0-95%, at 35°C. The obtained isotherms were found to be well described by the n-layer Brunauer-Emmet-Teller (BET) adsorption model. The water isotherms on HM-pectin were Type II (IUPAC), while water isotherms on liposomes were Type III. The maximum water sorption capacity of liposomes (1.2mg water per mg of adsorbent at 95% RH) was found to be twice as high as for pectin. Due to the slower water release from the liposomes, as well as their high water sorption capacity, they seem to have great potential in relieving the symptoms of dry mouth syndrome.

  14. Equilibrium sorption isotherm studies of Cd(II), Pb(II) and Zn(II) ions detoxification from waste water using unmodified and EDTA-modified maize husk

    OpenAIRE

    Igwe,Jude C; Abia,Augustin A

    2007-01-01

    The mobilization of heavy metals in the environment due to industrial activities is of serious concern due to the toxicity of these metals in humans and other forms of life. The equilibrium adsorption isotherms of Cd(II), Pb(II) and Zn(II) ions, detoxification from waste water using unmodified and EDTA-modified maize husk have been studied. Maize husk was found to be an excellent adsorbent for the removal of these metal ions. The amount of these metal ions adsorbed increased as the initial co...

  15. Carbon Dioxide Sorption Isotherm Study on Pristine and Acid-Treated Olivine and Its Application in the Vacuum Swing Adsorption Process

    Directory of Open Access Journals (Sweden)

    Jiajie Li

    2015-05-01

    Full Text Available This paper investigates the potential of pristine and acid-treated olivine as a substrate for CO2 capture using a vacuum swing adsorption (VSA process from the gas-solid phase. The experiments tested the isotherm of pure CO2 adsorption with partial pressure from 10−5 to 1 bar at ambient temperature. The CO2 adsorption capacity and actual expected working capacity (EWC curves of pristine and acid-treated olivine were determined. Isotherm studies predict that physisorption dominates chemisorptions at ambient temperatures. The adsorption capacity enhances with the increase of specific surface area, pore volume, and the appearance of Mg complexed on the mineral’s surface. Actual EWC studies showed that acid-treated olivine is an adsorbent choice for the VSA process, due to enhanced CO2 adsorption capacities compared to olivine and the potential for 100% recovery of CO2 during the regeneration process. Pristine olivine is not suitable for the VSA process because of bad regenerability, but it can be used in capturing and sequestering dilute CO2 in process streams. Our research reveals excellent viability for the application of VSA in the area of CO2 capture using pristine olivine and acid-treated olivine.

  16. Isotherm Studies of Equilibrium Sorption of Cu2+ and Cd2+ from Aqueous Solutions by Modified and Unmodified Breadfruit Seed Hull

    Directory of Open Access Journals (Sweden)

    Christopher Uchechukwu Sonde

    2015-09-01

    Full Text Available The ability of an economically cheap adsorbent material of natural origin, African breadfruit seed hull, was assessed for Cu(II and Cd(II ions’ adsorption from aqueous solutions. The effects of adsorbent dose, particle size and initial metal ion concentrations were investigated in a batch adsorption process. The experimental data were analyzed using five two-parameter isotherm equations (i.e., Langmuir, Freundlich, Temkin, Harkins-Jura and Halsey isotherm models. Freundlich and Halsey models provided the best description for the adsorption data while the other three models gave fairly good interpretation to the experimental adsorption data. The maximum adsorption capacity corresponding to saturation of sites (qmax, obtained from the Langmuir plots, were 7.76 and 8.06 mg g-1 for Cu(II and Cd(II onto the unmodified breadfruit seed hull (UBSH and 12.67 and 13.97 mg g-1, respectively for Cu(II and Cd(II adsorption onto the modified breadfruit seed hull (MBSH. The experimental results showed that there was an enhancement in the removal of the metal ions by the mercaptoacetic acid-modified breadfruit seed hull. DOI: http://dx.doi.org/10.17807/orbital.v7i3.625 

  17. The influence of clay surface modification with berberine on the sorption of anthocyanins

    Science.gov (United States)

    Chulkov, A. N.; Deineka, V. I.; Tikhova, A. A.; Vesentzev, A. I.; Deineka, L. A.

    2012-03-01

    The influence of preliminary sorption of berberine on the sorption of anthocyanins by bentonite clay was studied. The cation exchange sorption mechanism was found to be replaced by hydrophobic sorption of these compounds after clay modification with berberine. The enthalpy of sorption along the initial isotherm part changed from endothermic to exothermic.

  18. Isotermas e calor isostérico de sorção do feijão Isotherms and isosteric heats of sorptions of the edible bean

    Directory of Open Access Journals (Sweden)

    Osvaldo Resende

    2006-09-01

    Full Text Available O teor de água de equilíbrio dos grãos de feijão foi determinado pelo método dinâmico-gravimétrico para temperaturas entre 25 e 55 °C e atividades de água para cada temperatura, entre 0,20 e 0,75. Observou-se que o teor de água decresce com o aumento da temperatura para uma dada atividade de água à semelhança dos produtos higroscópicos. Aos dados experimentais foram ajustados diversos modelos matemáticos disponíveis na literatura (Brunauer-Emmett-Teller, Chung Pfost, Copace, Guggenhein-Anderson-de Boer, Halsey Modificado, Henderson, Henderson Modificado, Oswin, Sabbah e Sigma Copace. Segundo os parâmetros estatísticos de análise, o modelo de Halsey Modificado foi o que descreveu melhor a higroscopicidade do feijão. A partir dos resultados obtidos calculou-se o calor isostérico para cada teor de água de equilíbrio. Observou-se que o calor isostérico aumenta com a diminuição do conteúdo de água do produto, indicando que a redução do teor de água aumenta a energia necessária para a remoção de água. Os valores de calor isostérico para os grãos de feijão na faixa de umidade de 10,10 a 21,71 (% b.s., variam de 3961 a 2718 kJ kg-1.The equilibrium moisture content of the edible bean was determined using the dynamic-gravimetric method for temperatures between 25 and 55 °C and water activity between 0.20 and 0.75. It was observed that the moisture content decreases when the temperature for a given water activity is increased. Experimental data were adjusted to mathematical models mentioned in the specific literature (Brunauer-Emmett-Teller, Chung Pfost, Copace, Guggenhein-Anderson-de Boer, Modified Halsey, Henderson, Modified Henderson, Oswin, Sabbah and Sigma Copace. According to the results obtained and statistical parameters, the Modified Halsey model was the most effective in representing the hygroscopicity of the edible bean. From the obtained results, the desorption isosteric heats for each equilibrium moisture

  19. Determinação do coeficiente de distribuição (Kd de benzo(apireno em solo por isotermas de sorção Determination of the distribution coefficient (kd of benzo(apyrene in soil using sorption isotherms

    Directory of Open Access Journals (Sweden)

    Adriana D'Agostinho

    2006-07-01

    Full Text Available Leaking of diesel oil from gas stations is frequent in Brazil. The presence of polycyclic aromatic hydrocarbons (PAHs, which are highly toxic is an indication of contamination by heavy hydrocarbons from diesel oil. Here were present the determination of the distribution coefficient (Kd of benzo(apyrene (the most carcinogenic of the PAHs in tropical soils using the sorption isotherm model. The sorption curves acquired for benzo(apyrene were of the S-type, probably due to the water/methanol experimental conditions. The sorption curves allowed calculation of the distribution coefficient (Kd. The experimental Kd values were lower than those calculated from literature Koc values (partition coefficient normalized by organic carbon, due mainly to the cosolvency effect and the percentage of organic matter and clay in soil.

  20. Batch Sorption Experiments: Langmuir and Freundlich Isotherm Studies for the Adsorption of Textile Metal Ions onto Teff Straw (Eragrostis tef Agricultural Waste

    Directory of Open Access Journals (Sweden)

    Mulu Berhe Desta

    2013-01-01

    Full Text Available Adsorption of heavy metals (Cr, Cd, Pb, Ni, and Cu onto Activated Teff Straw (ATS has been studied using batch-adsorption techniques. This study was carried out to examine the adsorption capacity of the low-cost adsorbent ATS for the removal of heavy metals from textile effluents. The influence of contact time, pH, Temperature, and adsorbent dose on the adsorption process was also studied. Results revealed that adsorption rate initially increased rapidly, and the optimal removal efficiency was reached within about 1 hour. Further increase in contact time did not show significant change in equilibrium concentration; that is, the adsorption phase reached equilibrium. The adsorption isotherms could be fitted well by the Langmuir model. The value in the present investigation was less than one, indicating that the adsorption of the metal ion onto ATS is favorable. After treatment with ATS the levels of heavy metals were observed to decrease by 88% (Ni, 82.9% (Cd, 81.5% (Cu, 74.5% (Cr, and 68.9% (Pb. Results indicate that the freely abundant, locally available, low-cost adsorbent, Teff straw can be treated as economically viable for the removal of metal ions from textile effluents.

  1. Kinetic and isotherm studies of bisphenol A adsorption onto orange albedo(Citrus sinensis): Sorption mechanisms based on the main albedo components vitamin C, flavones glycosides and carotenoids.

    Science.gov (United States)

    Kamgaing, Theophile; Doungmo, Giscard; Melataguia Tchieno, Francis Merlin; Gouoko Kouonang, Jimmy Julio; Mbadcam, Ketcha Joseph

    2017-07-03

    Orange albedo and its adsorption capacity towards bisphenol A (BPA) were studied. Adsorption experiments were conducted in batch mode at 25-55°C. Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the biosorbent. The effects of various parameters including adsorption time, equilibrium pH, adsorbent dosage and initial adsorbate concentration were investigated. The optimum contact time and pH for the removal of BPA were 60 min and 2, respectively. It was found that the adsorption isotherms best matched the Freundlich model, the adsorption of BPA being multilayer and that of the albedo surface heterogeneous. From the kinetic studies, it was found that the removal of BPA best matched the pseudo-second order kinetic model. An adsorption mechanism based on the albedo surface molecules is proposed and gives a good account of π-π interactions and hydrogen bonding. Orange albedo, with a maximum BPA loading capacity of 82.36 mg g(-1) (significantly higher than that of most agricultural residues), is a good candidate for BPA adsorption in aqueous media.

  2. A Literature Review on the Study of Moisture in Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Trautschold, Olivia Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-25

    This literature review covers the main chemical and physical interactions between moisture and the polymer matrix. Fickian versus Non-Fickian diffusion behaviors are discussed in approximating the characteristics of moisture sorption. Also, bound water and free water sorbed in polymers are distinguished. Methods to distinguish between bound and free water include differential scanning calorimetry, infrared spectroscopy, and time-domain nuclear magnetic resonance spectroscopy. The difference between moisture sorption and water sorption is considered, as well as the difficulties associated with preventing moisture sorption. Furthermore, specific examples of how moisture sorption influences polymers include natural fiber-polymer composites, starch-based biodegradable thermoplastics, and thermoset polyurethane and epoxies.

  3. Sorption isotherms, kinetic and optimization process of amino acid proline based polymer nanocomposite for the removal of selected textile dyes from industrial wastewater.

    Science.gov (United States)

    Raghunath, Sharista; Anand, K; Gengan, R M; Nayunigari, Mithil Kumar; Maity, Arjun

    2016-12-01

    In this article, adsorption and kinetic studies were carried out on three textile dyes, namely Reactive Blue 222 (RB 222), Reactive Red 195 (RR 195) and Reactive Yellow 145 (RY 145). The dyes studied in a mixture were adsorbed under various conditions onto PRO-BEN, a bentonite modified with a new cationic proline polymer (l-proline-epichlorohydrin polymer). The proline polymer was characterized by (1)H NMR, Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS) and TEM. The PRO-BEN composite was characterized by FT-IR, dynamic light scattering (DLS) (zeta potential), TEM imaging, SEM/EDX and X-ray photoelectron spectroscopy (characterize the binding energy). During adsorption studies, factors involving pH, temperature, the initial concentrations of the dyes and the quantity of PRO-BEN used during adsorption were established. The results revealed that the adsorption mechanism was categorized by the Langmuir type 1 isotherm. The adsorption data followed the pseudo-second order kinetic model. The intraparticle diffusion model indicated that adsorption did not only depend on the intraparticle diffusion of the dyes. The thermodynamic parameters verified that the adsorption process was spontaneous and exothermic. The Gibbs free energy values indicated that physisorption had occurred. Successful adsorption of dyes from an industrial effluent was achieved. Desorption studies concluded that PRO-BEN desorbed the dyes better than alumina. This can thereby be viewed as a recyclable remediation material. The PRO-BEN composite could be a cost efficient alternative towards the removal of organic dyes in wastewater treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Manganese Nitride Sorption Joule-Thomson Refrigerator

    Science.gov (United States)

    Jones, Jack A.; Phillips, Wayne M.

    1992-01-01

    Proposed sorption refrigeration system of increased power efficiency combines MnxNy sorption refrigeration stage with systems described in "Regenerative Sorption Refrigerator" (NPO-17630). Measured pressure-vs-composition isotherms for reversible chemisorption of N2 in MnxNy suggest feasibility to incorporate MnxNy chemisorption stage in Joule-Thomson cryogenic system. Discovery represents first known reversible nitrogen chemisorption compression system. Has potential in nitrogen-isotope separation, nitrogen purification, or contamination-free nitrogen compression.

  5. 从热力学和动力学角度探讨中药吸湿机制%Study on moisture sorption mechanism of traditional Chinese medicine from the View of thermodynamics and dynamics

    Institute of Scientific and Technical Information of China (English)

    熊耀坤; 冯怡; 肖飞艳; 罗晓健; 辛洪亮; 林婷婷; 何雁

    2011-01-01

    Objective:To analyze moisture sorption mechanism of traditional Chinese medicine. Methods:Refered to large amount of internal and abroad documents, make a summary.Results:The basic study on hygroscopicity of traditional Chinese medicine is deficiency,the cognition of moisture still remain the stage of direct-viewing describtion and conjecture. We analyz moisture sorption mechanism of traditional Chinese medicine by some basic theory,such as:adsorption theory,theory of capillary condensation and Fick's diffusion theorem,to study the process of absorbing thermodynamics of water, the capillary action of Internal water phase change process, the relationship between water's diffusing and moisture absorption rate, to explore the mechanism of absorption of Chinese medicine from the view of energy Changes and power perspective of moisture absorption.Meanwhile,we work on further study on traditional Chinese medicine extract about its characteristics and hygroscopic material basis.Conclusion:we can explore the hygroscopicity problem of traditional Chinese medicine and its extract about by mathematic model and theoretical analysis, quantizing the process of moisture sorption,then, guide to solve the problem of hygroscopicity of traditional Chinese medicine in thc process of produce and storage. It is of great value on theoretical guidance and application.%目的:从热力学和动力学角度分析中药吸湿机制.方法:通过查阅国内外相关文献,并进行归纳总结.结果:中药吸湿性缺乏相关的基础研究,对吸湿性的了解仍停留在直观描述和猜测等感性认识阶段,本文从现有的吸附理论、毛细管的凝结理论和Fick's扩散定理等基础理论来探讨中药水分吸附的热力学过程、中药内部毛细管作用下水分的相变过程以及水分扩散与吸湿速率间的关系,从吸湿的能量变化和吸湿动力角度出发,探求中药的吸湿机制.同时,对中药提取物的吸湿特性和物质基础进一

  6. Sorption induced relaxations during water diffusion in S-PEEK

    NARCIS (Netherlands)

    Potreck, Jens; Uyar, Fuat; Sijbesma, Hylke; Nijmeijer, Kitty; Stamatialis, Dimitris; Wessling, Matthias

    2009-01-01

    This paper presents an analysis of the sorption kinetics of water vapor and liquid water in the glassy polymer sulfonated poly(ether ether ketone) (S-PEEK). Sorption isotherms are determined experimentally using a gravimetric sorption balance, and the relative contributions of Fickian diffusion and

  7. Sorption behavior of o-nitrophenol on marine sediment

    Institute of Scientific and Technical Information of China (English)

    YANG Guipeng; WU Ping; KONG Dexin

    2005-01-01

    Systematic study on sorption behavior of o-nitrophenol on marine sediments was conducted.Isotherms of sorption of o-nitrophenol on marine sediments could be described by Freundlich model; and the isotherm of sorption of o-nitrophenol on HCl-treated sediment could be described by Langmuir model. The sorption behavior was affected by various factors including organic carbon content, aqueous solution salinity,temperature, and acidity. The sorption amount of o-nitrophenol increased when salinity and acidity of the aqueous solution increase, but decreased with increasing temperature. Organic carbon content in sediments had apparent effect on the behavior except for HCl-treated sediments.

  8. Modelling of moisture adsorption for sugar palm (Arenga pinnata) starch film

    Science.gov (United States)

    Jatmiko, Tri Hadi; Poeloengasih, Crescentiana D.; Prasetyo, Dwi Joko; Hernawan

    2017-03-01

    Sorption characteristic of food products is important for design, optimization, storage and modelling. Sugar palm starch film with two different plasticizers (sorbitol and glycerol) with varied concentration studied for its adsorption isotherm characteristic. The data of adsorption isotherm fitted with GAB, Oswin, Smith and Peleg models. All models describe the experiment data well, but Peleg model is better than the other models on both sugar palm starch film plasticized with sorbitol and glycerol. Moisture sorption of sugar palm starch increased linearly with plasticizer concentration. A new model by taking account of plasticizer concentration describes the experiment data well with an average of coefficients of determination (R2) 0.9913 and 0.9939 for film plasticized with glycerol and sorbitol respectively.

  9. 水蒸气等温吸附表征水泥基材料孔隙结构%Characterization of Pore Structure of Cement-based Materials by Water Vapor Sorption Isotherms

    Institute of Scientific and Technical Information of China (English)

    罗明勇; 曾强; 庞晓贇; 李克非

    2013-01-01

    Using water vapor sorption isotherm (WVSI) and mercury intrusion porosimetery (MIP) and equilibrium isotherm model of Guggenheim-/Andersen-de Boer (GAB), the WVSI data were used to characterize the pore structure of blended paste, mortar and concrete with water-binder of 0.45. The adsorption, desorption and hysteretic curves of WVSI, and the pore size distribution (PSD) by both WVSI and MIP were analyzed. The results show that the aggregates have little effect on the adsorption and desorption WVSI curves. The adsorption/desorption hysteresis occurs in the whole range of relative humidity (RH) with the maximum hysteresis at RH of 80%. The adsorbed layer can improve the accuracy of PSD from WVSI data. The specific surface area and porosity from WVSI data are comparable with those from MIP. The energy instability in micro-pores (3 nm) can account for the adsorption/desorption hysteresis.%采用水胶比0.45的净浆、砂浆和混凝土材料,以水蒸气等温吸附法和压汞法为试验方法,以GAB吸附模型为数据分析手段,通过等温吸附曲线、脱附曲线、滞回曲线和孔隙分布,研究使用水蒸气等温吸附法表征水泥基材料的孔隙结构。研究结果表明:骨料对水泥基材料的水蒸气等温吸附曲线几乎没有影响;水泥基材料吸附/脱附滞回曲线出现在整个湿度区域,并在湿度为80%达到最大值;考虑表面吸附层能够提高水蒸气等温吸附计算的孔隙分布精度;水蒸气等温吸附法得到的孔隙率和比表面积与压汞法得到的数值具有正相关性;微孔(r3 nm)中“墨水瓶”效应是水蒸气等温吸附过程滞回现象的主要原因。

  10. ISOTERMAS DE SORCION DE AGUA EN RESIDUOS DE EXTRACCIÓN DE JUGO DE NARANJA ISOTERMAS DE SORCAO DA AGUA EM RESIDUOS DE EXTRACAO DE SUCO DE LARANJA SORPTION ISOTHERMS OF WATER IN ORANGE JUICE EXTRACTION RESIDUES

    Directory of Open Access Journals (Sweden)

    MÓNICA OMAÑA

    2010-06-01

    não varié ou alcance o equilibrio. Além demais, realizouse um ajuste com o modelo proposto pelo Smith obtendose erros medios de 8.56% e 7.57% para Túnez e Pomelo, respectivamente.Waste from orange juice extraction, such as skins, shells and seeds, are known as citrus pulp, they may cause two major impacts, be a potential source ofraw material in the food industry concentrates for animals, and reduce problem posed to the environment with unnecessary use of landfills. The purpose of this paper is to obtain experimental sorption isotherms of this waste, at a temperature of 20° in a wide range of water activity (0.33 -0.97 from the two producers of orange juice, called Túnez and Pomelo. The process used to determine isothermal sorption curves, is the method recommended by the COST Project 90, which consisted of placing a known amount of sample in an airtight container with a given relative humidity until the weight does not vary orreaches balance. In addition, an adjustment to the model proposed by Smith obtained average errors of 8.56% and 7.57% for Túnez and Pomelo, respectively.

  11. Thermodynamic properties of water sorption of jackfruit (Artocarpus heterophyllus Lam. as a function of moisture content Propriedades termodinâmicas de sorção de água da jaca (Artocarpus heterophyllus Lam. em função do teor de umidade

    Directory of Open Access Journals (Sweden)

    Ana Paula Prette

    2013-03-01

    Full Text Available The Jackfruit tree is one of the most significant trees in tropical home gardens and perhaps the most widespread and useful tree in the important genus Artocarpus. The fruit is susceptible to mechanical and biological damage in the mature state, and some people find the aroma of the fruit objectionable, particularly in confined spaces. The dehydration process could be an alternative for the exploitation of this product, and the relationship between moisture content and water activity provides useful information for its processing and storage. The aim of this study was to determine the thermodynamic properties of the water sorption of jackfruit (Artocarpus heterophyllus Lam. as a function of moisture content. Desorption isotherms of the different parts of the jackfruit (pulp, peduncle, mesocarp, peel, and seed were determined at four different temperatures (313.15, 323.15, 333.15, and 343.15 K in a water activity range of 0.02-0.753 using the static gravimetric method. Theoretical and empirical models were used to model the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to calculate the isosteric heat of sorption, the differential entropy, and Gibbs' free energy using the Guggenhein-Anderson-de Boer and Oswin models considering the effect of temperature on the hygroscopic equilibrium.A jaqueira é uma das árvores mais significativas nos quintais tropicais e, talvez, a árvore mais importante e útil do gênero Artocarpus. O fruto é suscetível a danos mecânicos e biológicos no estado maduro, e seu aroma é desagradável para algumas pessoas, quando em espaços fechados. O processo de desidratação pode ser uma alternativa para a exploração deste produto, e a relação entre a umidade e a atividade de água fornece informações úteis para seu processamento e armazenamento. O objetivo do trabalho foi determinar as propriedades termodinâmicas de sorção da água em frutos de jaca (Artocarpus

  12. Sorption of water by biochar: Closer look at micropores

    Science.gov (United States)

    Spokas, Kurt; Hall, Kathleen; Joseph, Stephan; Kammann, Claudia; Novak, Jeffrey; Gámiz, Beatriz; Cox, Lucia

    2017-04-01

    Typically, biochar has been assumed to increase total water content of the soil system and thereby positively influence plant-soil moisture hydraulics. In this work, we focused on water's interaction with micro-pores (biochar pores. The temporal scale of liquid water entry into biochar's pore network is very complex, with observed bubbling occurring days, weeks, and even months after a piece of biochar is immersed under water at ambient conditions. Elevated temperature biochar typically has a positive heat of immersion measured calorimetrically, whereas the calculated BET energy of sorption from a water sorption isotherm typically decrease with production temperatures. To further complicate matters, different pieces of biochar interact differently with water even though the entire batch was created in the same reactor at the same time and after liquid water exposure the physical structure of biochar is irreversibly altered, sometimes negligible other times catastrophically. Nevertheless, based on the estimations of diffusion coefficients in biochar from drying curve analyses, pore surface moieties do reduce the effective diffusivity of water vapor in biochar. Contrary to the rule of thumb in soil physics, where higher gas filled porosity correlates with higher soil moisture holding capacities, our results indicate that biochar's water sorption rate and capacity is actually reduced at ambient conditions by an increase in microporous volume. Thereby, biochar's hydrophobic behavior is partly due to the entrapment of gas within the air-filled porosity which prevents liquid water's entry, even though these biochars possess elevated gas phase sorption capacities (e.g., BET N2/CO2 surface areas).

  13. EFFECTS OF BIOSOLIDS ON SORPTION AND DESORPTION BEHAVIOR OF CADMIUM IN BIOSOLIDS-AMENDED SOILS

    Science.gov (United States)

    Cadmium sorption and desorption experiments were conducted on different fractions of soils amended with different biosolids with varying chemical properties and unamended soil (control). Biosolids addition increased the slope of the Cd sorption isotherms compared to the control s...

  14. Hydration and sorption characteristics of a polyfunctional weak-base anion exchanger after the sorption of vanillin and ethylvanillin

    Science.gov (United States)

    Rodionova, D. O.; Voronyuk, I. V.; Eliseeva, T. V.

    2016-07-01

    Features of the sorption of substituted aromatic aldehydes by a weak-base anion exchanger under equilibrium conditions are investigated using vanillin and ethylvanillin as examples. Analysis of the sorption isotherms of carbonyl compounds at different temperatures allows us to calculate the equilibrium characteristics of their sorption and assess the entropy and enthalpy contributions to the energy of the process. Hydration characteristics of the macroporous weak-base anion exchanger before and after the sorption of aromatic aldehydes are compared.

  15. Thermodynamics of cationic surfactant sorption onto natural clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, E.J.; Bowman, R.S. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Carey, J.W. [Los Alamos National Lab., NM (United States)

    1998-10-15

    Sorption enthalpies of hexadecyltrimethylammonium bromide (HDTMA) as monomers and micelles and tetraethylammonium bromide (TEA) were used with surfactant, counterion, and co-ion sorption isotherms to infer the conformation, sorption mechanism, and relative stability of the sorbed surfactants on natural clinoptilolite. The average value of the sorption enthalpy was {minus}10.38 kJ/mol for monomers, {minus}11.98 kJ/mol for micelles, and +3.03 kJ/mol for TEA. Sorption of monomers produced a lower sorption plateau than equivalent micelle sorption (maxima 145 mmol/kg, 225 mmol/kg). Analysis of the sorption data demonstrated a change in the sorption mechanism at the external cation exchange capacity (ECEC) of clinoptilolite. Sorption data from below and above the ECEC were fit to a simple polynomial model and the Gibbs free energy of sorption ({Delta} G{sub m}{sup 0}) and sorption entropies were calculated. Resultant values of {Delta} G{sub m}{sup 0} were {minus}9.27 and {minus}14.38 kJ/mol for HDTMA monomers and micelles, respectively, for sorption below the ECEC, and {minus}16.11 and {minus}23.10 kJ/mol, respectively, for sorption above the ECEC. The value for TEA was {minus}1.04 kJ/mol, indicating weaker sorption than for HDTMA. Monomer sorption to clinoptilolite exceeded the ECEC, even when the solution concentration was below the critical micelle concentration. Hydrophobic (tail-tail) components of {Delta} G{sub m}{sup 0} were the driving force for sorption of HDTMA, both below and above the ECEC. A significant kinetic effect was observed in the sorption isotherms with a period of rapid sorption followed by slow equilibration requiring 7 days to achieve steady state for HDTMA; TEA equilibration occurred within 24 h.

  16. Modeling temperature and moisture fields in conditioned spaces using zonal approach, including sorption phenomena in buildings materials; Modelisation thermo-hydro-aeraulique des locaux climatises selon l'approche zonale (prise en compte des phenomenes de sorption d'humidite)

    Energy Technology Data Exchange (ETDEWEB)

    Cordeiro Mendoca, K.

    2004-05-15

    Building simulation models represent in our days an important tool for building conception and performance analysis. Although moisture interacts in many ways with the whole building affecting therefore its behavior, frequently these models neglects the interactions between them. In addition, in most of them, indoor air conditions are considered uniform, which is a non-realistic assumption in conditioned spaces. In this work, a model to predict temperature and moisture fields in conditioned spaces, using zonal approach, is proposed. This method is based in dividing spatially a room in a relative small number of zones, typically on the order of tens to hundreds, where the state variables of air are considered uniform, with the exception of pressure that varies hydrostatically. While not as fine-grained as CFD simulation, zonal models do give useful information about temperature and moisture distributions that is important in comfort analysis. The proposed model was structured in three groups of sub-models representing the three building domains: indoor air, envelope and HVAC system. The indoor air sub-model is related to the indoor air space, where airflow speed can be considered weak. The envelope sub-model is related to the radiation exchanges between envelope and its neighborhood, and to the simultaneous heat and mass transfers across the envelope material. This latest can be represented by four sub-models of different complexity levels, with two of them taking into account moisture adsorption and desorption by building materials. Concerning to the HVAC system model, it refers to the whole system that means equipment, control and specific airflow from equipment. All sub-models were coupled into a modular simulation environment, SPARK, well-adapted to compare different models. The applicability of the proposed model is shown by two examples. The first one shows the importance of considering moisture sorption phenomena in the prediction of indoor air conditions

  17. Determination of sorption of seventy five pharmaceuticals in sewage sludge

    DEFF Research Database (Denmark)

    Hörsing, Maritha; Ledin, Anna; Grabic, Roman

    2011-01-01

    Sorption of 75 active pharmaceutical ingredients (APIs) to three different types of sludge (primary sludge, secondary sludge with short and long sludge age respectively) were investigated. To obtain the sorption isotherms batch studies with the APIs mixture were performed in four nominal concentr......Sorption of 75 active pharmaceutical ingredients (APIs) to three different types of sludge (primary sludge, secondary sludge with short and long sludge age respectively) were investigated. To obtain the sorption isotherms batch studies with the APIs mixture were performed in four nominal...

  18. Enhanced fluoride sorption by mechanochemically activated kaolinites.

    Science.gov (United States)

    Meenakshi, S; Sundaram, C Sairam; Sukumar, Rugmini

    2008-05-01

    Kaolinite clay obtained from the mines was processed and studied for its fluoride sorption capacity. The surface area of the clay mineral was increased from 15.11 m(2)/g (raw) to 32.43 m(2)/g (activated) by mechanochemical activation. Batch adsorption studies were conducted to optimize various equilibrating conditions like the effect of contact time, dosage, pH for both raw and micronized kaolinites (RK and MK). The effect of other interfering anions on the defluoridation capacity (DC) of the sorbents was studied. Sorption of fluoride by the sorbents was observed over a wide pH range of 3-11. The studies revealed there is an enhanced fluoride sorption on MK. FTIR and XRD were used for the characterization of the sorbent. The surface morphology of the clay material was observed using SEM. The adsorption of fluoride was studied at three different temperatures, viz., 303, 313 and 323 K. The sorption data obtained at optimized conditions were subjected to Freundlich and Langmuir isotherms. Sorption intensity (1/n) (0.770-0.810) has been evaluated using Freundlich isotherm, whereas the values of sorption capacity Q(0) (0.609, 0.714 and 0.782 mg/g) and binding energy b (0.158, 0.145 and 0.133 L/mg) at three different temperatures have been estimated using Langmuir isotherm. Adsorption process was found to be controlled by both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the sorption of fluoride on MK is endothermic and a spontaneous process. The kinetic studies indicate that the sorption of fluoride on MK follows pseudo-first-order and intraparticle diffusion models.

  19. Enhanced fluoride sorption by mechanochemically activated kaolinites

    Energy Technology Data Exchange (ETDEWEB)

    Meenakshi, S. [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Tamilnadu (India)], E-mail: drs_meena@rediffmail.com; Sundaram, C. Sairam [Department of Science and Humanities, Karaikal Polytechnic College, Karaikal 609609, Puducherry (India); Sukumar, Rugmini [Chemical Sciences and Technologies, Regional Research Laboratory, Trivandrum 695019, Kerala (India)

    2008-05-01

    Kaolinite clay obtained from the mines was processed and studied for its fluoride sorption capacity. The surface area of the clay mineral was increased from 15.11 m{sup 2}/g (raw) to 32.43 m{sup 2}/g (activated) by mechanochemical activation. Batch adsorption studies were conducted to optimize various equilibrating conditions like the effect of contact time, dosage, pH for both raw and micronized kaolinites (RK and MK). The effect of other interfering anions on the defluoridation capacity (DC) of the sorbents was studied. Sorption of fluoride by the sorbents was observed over a wide pH range of 3-11. The studies revealed there is an enhanced fluoride sorption on MK. FTIR and XRD were used for the characterization of the sorbent. The surface morphology of the clay material was observed using SEM. The adsorption of fluoride was studied at three different temperatures, viz., 303, 313 and 323 K. The sorption data obtained at optimized conditions were subjected to Freundlich and Langmuir isotherms. Sorption intensity (1/n) (0.770-0.810) has been evaluated using Freundlich isotherm, whereas the values of sorption capacity Q{sup 0} (0.609, 0.714 and 0.782 mg/g) and binding energy b (0.158, 0.145 and 0.133 L/mg) at three different temperatures have been estimated using Langmuir isotherm. Adsorption process was found to be controlled by both Freundlich and Langmuir isotherms. Thermodynamic studies revealed that the sorption of fluoride on MK is endothermic and a spontaneous process. The kinetic studies indicate that the sorption of fluoride on MK follows pseudo-first-order and intraparticle diffusion models.

  20. Sorption equilibria of ethanol on cork.

    Science.gov (United States)

    Lequin, Sonia; Chassagne, David; Karbowiak, Thomas; Bellat, Jean-Pierre

    2013-06-01

    We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of ethanol becomes lower than the liquefaction enthalpy as the filling increases. This result could be attributed to the swelling of the material, which would generate endothermic effects. Sorption of SO₂ on cork containing ethanol was also studied. When the ethanol content in cork is 2 wt %, the amount of SO₂ sorbed is divided by 2. Thus, ethanol does not enhance the sorption rate for SO₂ but, on the contrary, decreases the SO₂ sorption activity onto cork, probably because of competitive sorption mechanisms.

  1. Water Sorption and Transport in Dry, Crispy Bread Crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, N.H. van; Tromp, R.H.; Hamer, R.J.; Vliet, T. van

    2010-01-01

    Water - sorption and dynamic properties of bread crust have been studied in gravimetric sorption experiments. Water uptake and loss were measured while relative humidity (RH) was stepwise increased or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment). Exp

  2. Water sorption and transport in dry crispy bread crust

    NARCIS (Netherlands)

    Meinders, M.B.J.; Nieuwenhuijzen, van N.H.; Tromp, R.H.; Hamer, R.J.; Vliet, van T.

    2010-01-01

    Water sorption and dynamical properties of bread crust have been studied using gravimetric sorption experiments. Water uptake and loss were followed while relative humidity (RH) was stepwise in- or decreased (isotherm experiment) or varied between two adjusted values (oscillatory experiment). Experi

  3. Kinetics and Equilibrium Sorption Models: Fitting Plutonium, Strontium, Uranium and Neptunium Loading on Monosodium Titanate (MST)

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F

    2006-03-08

    The Dubinin-Astashov (DA) isotherm parameters for U, Pu, Sr and Np have been updated to include additional data obtained since the original derivation. The DA isotherms were modified to include a kinetic function derived by Rahn to describe sorbate loading from the beginning of sorption up to steady state. The final functions describe both kinetic and thermodynamic sorption.

  4. Sorption of Ochratoxin A from aqueous solutions using beta-cyclodextrin-polyurethane polymer

    Science.gov (United States)

    The ability of a cyclodextrin-polyurethane polymer to remove ochratoxin A from aqueous solutions, including wine, was examined by batch rebinding assays and equilibrium sorption isotherms. The results were fit to two parameter models. Freundlich analysis of the sorption isotherm indicates the polyme...

  5. Groundwater transport modeling with nonlinear sorption and intraparticle diffusion

    Science.gov (United States)

    Singh, Anshuman; Allen-King, Richelle M.; Rabideau, Alan J.

    2014-08-01

    Despite recent advances in the mechanistic understanding of sorption in groundwater systems, most contaminant transport models provide limited support for nonideal sorption processes such as nonlinear isotherms and/or diffusion-limited sorption. However, recent developments in the conceptualization of "dual mode" sorption for hydrophobic organic contaminants have provided more realistic and mechanistically sound alternatives to the commonly used Langmuir and Freundlich models. To support the inclusion of both nonlinear and diffusion-limited sorption processes in groundwater transport models, this paper presents two numerical algorithms based on the split operator approach. For the nonlinear equilibrium scenario, the commonly used two-step split operator algorithm has been modified to provide a more robust treatment of complex multi-parameter isotherms such as the Polanyi-partitioning model. For diffusion-limited sorption, a flexible three step split-operator procedure is presented to simulate intraparticle diffusion in multiple spherical particles with different sizes and nonlinear isotherms. Numerical experiments confirmed the accuracy of both algorithms for several candidate isotherms. However, the primary advantages of the algorithms are: (1) flexibility to accommodate any isotherm equation including "dual mode" and similar expressions, and (2) ease of adapting existing grid-based transport models of any dimensionality to include nonlinear sorption and/or intraparticle diffusion. Comparisons are developed for one-dimensional transport scenarios with different isotherms and particle configurations. Illustrative results highlight (1) the potential influence of isotherm model selection on solute transport predictions, and (2) the combined effects of intraparticle diffusion and nonlinear sorption on the plume transport and flushing for both single-particle and multi-particle scenarios.

  6. Cd(II) Sorption on Montmorillonite-Humic acid-Bacteria Composites

    OpenAIRE

    Du, H.; Chen, W.; Cai, P.; Rong, X; Dai, K; Peacock, CL; Huang, Q.

    2016-01-01

    Soil components (e.g., clays, bacteria and humic substances) are known to produce mineral-organic composites in natural systems. Herein, batch sorption isotherms, isothermal titration calorimetry (ITC), and Cd K-edge EXAFS spectroscopy were applied to investigate the binding characteristics of Cd on montmorillonite(Mont)-humic acid(HA)-bacteria composites. Additive sorption and non-additive Cd(II) sorption behaviour is observed for the binary Mont-bacteria and ternary Mont-HA-bacteria composi...

  7. ISOTERMAS DE DESORCION DE HUMEDAD EN PITAHAYA AMARILLA (Selenicereus megalanthus ISOTERMAS DE DESSORÇÃO DE UMIDADE EM PITAIAIÁS AMARELO (Selenicereus megalanthus MOISTURE DESORPTION ISOTHERMS IN YELLOW PITAHAYA (Selenicereus megalanthus

    Directory of Open Access Journals (Sweden)

    ALFREDO A. AYALA-APONTE

    2012-12-01

    Full Text Available Se determinaron las isotermas de desorción de humedad en pitahaya amarilla a 15, 25 y 35°C mediante el método gravimétrico en el intervalo de actividad de agua entre 0.111 y 0.901. Los valores experimentales de desorción se ajustaron mediante los modelos de GAB, Henderson, Smith, Oswin y Chung y Fost, usualmente usados en alimentos. El calor isostérico de desorción (Qst se determinó mediante la ecuación de Clausius-Clapeyron. Los resultados mostraron que las isotermas fueron de tipo III. El contenido de humedad de equilibrio (CHE presentó dependencia con la temperatura, esta disminuyó con el aumento de la temperatura para un valor constante de actividad de agua. El modelo GAB fue el de mejor ajuste de los valores experimentales. El Qst disminuyó con el aumento del CHE, desde 61.43 hasta 45.11 kJ/mol para humedades de 0.08 hasta 0.56 (g agua/g ms respectivamente.Se determinaram as isotermas de dessorção de humidade da pitaiaiás amarela, 15, 25 y 35°C utilizando-se o método estático gravimétrico numafaixa de atividade de água entre 0.111 e 0.90, Os valores experimentais de adsorçãoforam ajustados pelos modelos de GAB, Henderson, Smith, Oswin y Chung y Fost, O calor isostérico de adsorção (Qst foi determinado pela ecuação de Clausius-Clapeyron. Os resultados mostraram que as isotermas obtidasforam do tipo III. O teor de humidade de equilíbrio (CHE apresentoudependênciacom a temperatura, diminuindocom o aumento desta a um valor constante de atividade de água. O modelo de GAB foi o que apresentou o melhor ajuste dos valores experimentais. O Qstdiminuíocom o aumento de CHE, obténdo-se um máximo e um mínimo entre 61.43 a 45.11 kJ / mol de humidade entre 0.08 e 0.56 (g de água / g bs, respectivamente.Moisture desorption isotherms for yellow pitahaya fruits were studied at 15, 25, and 35°C using the gravimetric method for a 0.111-0.901 water activity range. Experimental values were adjusted by using the GAB, Henderson

  8. Nitrate Sorption in an Agricultural Soil Profile

    Directory of Open Access Journals (Sweden)

    Wissem Hamdi

    2013-01-01

    Full Text Available Increasing concentrations of in surface water and groundwater can cause ecological and public health effects and has come under increased scrutiny by both environmental scientists and regulatory agencies. For many regions though, including the Sahel of Tunisia, little is known about the sorption capacity of soils. In this project we measured sorption by a profile of an iso-humic soil from Chott Meriem, Tunisia. Soil samples were collected from four soil depths (0–25, 25–60, 60–90, and 90–120 cm on 1 June 2011, and their sorption capacity was determined using batch experiments under laboratory conditions. The effects of contact time, the initial concentration, and the soil-solution ratio on sorption were investigated. In general, the results suggested that was weakly retained by the Chott Meriem soil profile. The quantity of sorption increased with depth, contact time, initial concentration, and soil-solution ratios. To evaluate the sorption capacities of the soil samples at concentrations ranging between 25 and 150 mg L−1 experimental data were fitted to both Freundlich and Langmuir isotherm sorption models. The results indicated that Freundlich model was better for describing sorption in this soil profile.

  9. Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

    Institute of Scientific and Technical Information of China (English)

    Shubo DENG; Danmeng SHUAI; Qiang YU; Jun HUANG; Gang YU

    2009-01-01

    Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics,isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS On the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

  10. Sorption of untreated and humic acid coated silver nanoparticles to environmental and model surfaces

    Science.gov (United States)

    Abraham, Priya M.; Baumann, Thomas; Schaumann, Gabriele E.

    2014-05-01

    The environmental fate of engineered nanoparticles is controlled their colloidal stability and their interaction with different environmental surfaces. Little is known about sorption of nanoparticles to environmental surfaces under quasi-equilibrium conditions. Nevertheless, sorption isotherms may also be a valuable means of studying nanoparticle-sorbent interactions. We investigated sorption of engineered silver nanoparticles (nAg) from stable and unstable suspensions in presence and absence of natural organic matter (NOM) to model surfaces (sorbents with specific chemical functional groups) and environmental materials (plant leaves and sand). Morphology and nanomechanical parameters of the surfaces covered with nanoparticles were assessed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The sorption of nAg from stable suspensions and in absence of NOM was non-linear and best described by a Langmuir model, where Langmuir coefficients varied with sorbent surface chemistry, which suggests monolayer sorption (Abraham et al. 2013). For nAg sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption (Abraham et al. 2013). In contrast, sorption was strongly suppressed and exhibited linear sorption isotherms in the presence of NOM. The difference in sorption isotherms suggests predominance of different sorption mechanisms depending on presence or absence of NOM, which can be only partly explained by the NOM coating alone. On the basis of the current results, a partial release of NOM coating for sorption of certain surfaces cannot be excluded. The validity of the Langmuir isotherm suggests monolayer sorption, which can be explained by the blocking effect due to electrostatic repulsion of individual nanoparticles. In unstable suspensions, aggregates are instead formed in suspension, formed on the surface and then sorbed, or formed in both ways

  11. MOISTURE ADSORPTION ISOTHERMS IN YELLOW PITAHAYA (Selenicereusmegalanthus

    Directory of Open Access Journals (Sweden)

    ALFREDO AYALA APONTE

    2011-01-01

    Full Text Available Se determinaron las isotermas de adsorción de humedad en pitahaya amarrilla a 15, 25, y 35ºC mediante el método gravímetro en el intervalo de actividad de agua (aw entre 0.111 y 0.901. Los valores experimentales de adsorción se ajustaron mediante los modelos de GAB, BET, Henderson, Smith, Caurie, y Peleg. El calor isostérico de adsorción (Qst se determinó mediante la ecuación de Clausius- Clapeyron. Los resultados mostraron que las isotermas fueron de tipo III. El contenido de humedad de equilibrio (CHE presentó dependencia con la temperatura, disminuyendo con el aumento de esta para un valor constante de aw. El modelo GAB fue el que presentó mejor ajuste de los valores experimentales. El Qst disminuyó con el aumento del CHE, variando de 57.154 a 45.79 kJ/mol para humedades de 0.05 y 0.4 (g agua/g ms, respectivamente. Estos resultados son de interés para establecer las mejores condiciones de almacenamiento de la pitahaya deshidratada, así como la predicción de la vida útil, y el diseño de empaque.

  12. Effects of Citrate and Arginine on Sorption of Nickel to Yazd Sepiolite and Calcite

    Directory of Open Access Journals (Sweden)

    Ahmadreza Sheikhhosseini

    2017-03-01

    , and W was the mass (g of the sorbent. The Langmuir, Freundlich and linear isotherm models were fitted to sorption data using Graphpad prism 5.0. For kinetic study,30 mL of 0.01 M CaCl2 solution, with or without 0.1 mM citrate or arginine, containing Ni at a concentration corresponding to the maximum sorption capacity of each mineral (estimated from sorption isotherms were transferred into 50-ml polyethylene centrifuge tubes containing 0.3 g of sepiolite or calcite. The suspensions were shaken (180±2 rpm, 25 °C continuously and after 0.5, 1.5, 3, 6, 12, 18 and 24 hours, corresponding tubes were centrifuged (4000×g for 10 min and supernatants were analyzed for Ni concentration by atomic absorption spectrophotometer. Using Graphpad prism 5.0, kinetic data were fitted to Pseudo-first order, pseudo-second order and power function kinetic models. Results: With or without ligands, the Langmuir model was the best description of Ni sorption to sepiolite while the linear model was the best fit of calcite data showing the physical nature of Ni sorption by this mineral. Kinetics of Ni sorption to sepiolite and calcite were best described by power function model. In the presence of citrate, both capacity and rate of sorption of Ni to sepiolite decreased. There was no considerable change in sorption of Ni to calcite. In the presence of arginine, however, sorption capacity of minerals for Ni increased. Arginine enhanced the rate of Ni sorption on all three minerals. Citrate showed opposing effects on Ni sorption kinetics depending on the studied minerals. Totally, citrate and arginine had opposite effects on sorption of Ni to sepiolite and calcite. Conclusion: Organic ligands can change sorption characteristics of the minerals. It seems that citrate decreases sorption of Ni to sepiolite but its effect on Ni sorption to calcite is negligible, while arginine increases Ni sorption to both minerals. Our results suggested that presence of citrate and arginine in soil influence Ni

  13. Experimental study of strontium sorption on fissure filling material

    Energy Technology Data Exchange (ETDEWEB)

    Eriksen, T.E.; Cui, Daqing [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemistry

    1994-12-01

    We have carried out a comparative study of sorption and desorption of strontium in groundwater on separated magnetic and size fractions of fissure filling material taken from natural fissures in granitic rock. Complete reversibility of the sorption process was demonstrated by identical Freundlich isotherms, isotopic exchangeability and pH dependence of the distribution coefficients Rd. The sorption was found to be strongly pH dependent in the range 3-11. The pH effect can be accommodated in the sorption model by considering the surface areas and surface charges of the minerals in the fissure filling material. 20 refs, 9 figs, 3 tabs.

  14. Influência da temperatura e da concentração do cloreto de sódio (NaCl nas isotermas de sorção da carne de tambaqui (Colossoma macroparum Influence of temperature and concentration of the chloride sodium(NaCl on sorption isotherms of tambaqui meat (Colossoma macroparum

    Directory of Open Access Journals (Sweden)

    Lucídio Molina-Filho

    2006-06-01

    Full Text Available As isotermas de sorção da carne de tambaqui desidratada osmoticamente foram determinadas a três temperaturas (5, 17 e 29ºC e com duas concentrações de solução osmótica (10 e 30% de NaCl, pelo método gravimétrico. Quatro modelos de sorção foram testados para verificar o melhor ajuste; GAB, Oswin, BET e PELEG. Os dados experimentais se ajustaram satisfatoriamente aos modelos. O modelo escolhido para este trabalho foi o de PELEG. Para o ajuste nas curvas de sorção, foi feita a análise de regressão não-linear, usada o programa estatístico ORIGIN 4.0 para estimar as constantes dos modelos. A avaliação do melhor ajuste foi feita pela análise do coeficiente de determinação do ajuste (r² e teste de Qui-quadrado (x². Foram analisadas as influências da variação da temperatura e concentração de NaCl na atividade de água da carne do tambaqui. À medida que decresce a temperatura há um decréscimo na atividade de água. Um aumento na concentração do NaCl diminui a atividade de água. A propriedade termodinâmica estudada foi o calor isostérico de sorção. A medida que aumenta a concentração da solução osmótica aumenta o valor do calor isostérico de sorção.Sorption isotherms were determined for tambaqui fish osmotic treated at three different temperatures (5, 17 e 29ºC and for two concentration (10 e 30% of NaCl, using a standard gravimetric method. Four mathematics models were tested to verify the best fit of the experimental data: GAB, Oswin, BET e PELEG. The experimental data fitted goodness to all models. The chosen model was PELEG. The adjustment on sorption isotherms curves was done by a non-linear regression, using statistical program ORINGIN 4.0 to esteem the constants of the models sorption isotherms. The evaluation of goodness fit was shown through the analysis of the coefficient of determination (r² and Qui-square (x². The influences of the temperature of the meat of the tambaqui had been analysed

  15. Determination of desorption isotherms, latent heat and isosteric heat of pequi diaspore

    Directory of Open Access Journals (Sweden)

    Kelly A. de Sousa

    2016-05-01

    Full Text Available ABSTRACT The objective was to determine water sorption isotherms of diaspores of pequi fruits in order to obtain information on the amount of water that this product desorbs at the temperatures of 10, 20, 30 and 40 °C and water activities from 0.20 to 0.89, adjusting different mathematical models to experimental data, and to determine its latent heat and isosteric heat. The equilibrium moisture content was obtained through the indirect static method, using the device Hygropalm Model Aw 1. The Modified Henderson model was the one that best fitted the data and was selected to predict the equilibrium moisture content of pequi diaspore. It was observed that the higher the temperature for the same equilibrium moisture content (% d.b., the higher the water activity values. As temperature values increased, there was a reduction in the vaporization latent heat of the product. Isosteric heat values of diaspores of pequi fruits in the moisture content range of 4.02 to 16.63 (% d.b. varied from 2,776.49 to 2,558.39 kJ kg-1.

  16. Computer simulation of molecular sorption in zeolites

    CERN Document Server

    Calmiano, M D

    2001-01-01

    The work presented in this thesis encompasses the computer simulation of molecular sorption. In Chapter 1 we outline the aims and objectives of this work. Chapter 2 follows in which an introduction to sorption in zeolites is presented, with discussion of structure and properties of the main zeolites studied. Chapter 2 concludes with a description of the principles and theories of adsorption. In Chapter 3 we describe the methodology behind the work carried out in this thesis. In Chapter 4 we present our first computational study, that of the sorption of krypton in silicalite. We describe work carried out to investigate low energy sorption sites of krypton in silicalite where we observe krypton to preferentially sorb into straight and sinusoidal channels over channel intersections. We simulate single step type I adsorption isotherms and use molecular dynamics to study the diffusion of krypton and obtain division coefficients and the activation energy. We compare our results to previous experimental and computat...

  17. Unified water isotherms for clayey porous materials

    Science.gov (United States)

    Revil, A.; Lu, N.

    2013-09-01

    We provide a unified model for the soil-water retention function, including the effect of bound and capillary waters for all types of soils, including clayey media. The model combines a CEC-normalized isotherm describing the sorption of the bound water (and the filling of the trapped porosity) and the van Genuchten model to describe the capillary water sorption retention but ignore capillary condensation. For the CEC-normalized isotherm, we tested both the BET and Freundlich isotherms, and we found that the Freundlich is more suitable than the BET isotherm in fitting the data. It is also easier to combine the Freundlich isotherm with the van Genuchten model. The new model accounts for (1) the different types of clay minerals, (2) the different types of ions sorbed in the Stern layer and on the basal planes of 2:1 clays, and (3) the pore size distribution. The model is validated with different data sets, including mixtures of kaolinite and bentonite. The model parameters include two exponents (the pore size exponent of the van Genuchten model and the exponent of the Freundlich isotherm), the capillary entry pressure, and two critical water contents. The first critical water content is the water content at saturation (porosity), and the second is the maximum water content associated with adsorption forces, including the trapped nonbound water.

  18. SORPTION PROPERTIES OF PERIODATE OXIDIZED COTTON

    Directory of Open Access Journals (Sweden)

    Tanja Nikolić

    2011-09-01

    Full Text Available The effect of periodate oxidation on the chemical and sorption properties of cotton yarn was investigated by determining aldehyde group content, moisture sorption, water retention and iodine sorption. Oxidation of cotton yarn was performed by varying concentration of sodium periodate solution and reaction time. To measure the aldehyde content present in the oxidized cotton, the aldehyde groups were selectively oxidized to carboxyl groups with sodium chlorite at pH 4-5, at room temperature for 48 h, and carboxyl group content was determined by modified calcium-acetate method. Differences in the sorption properties of untreated and oxidized cotton samples were obtained using conventional methods. The aldehyde groups were introduced into the oxidized cotton up to 99.2 µmol/g. Compared to the untreated fibers, oxidized cotton samples exhibited higher moisture sorption (up to 9% and lower water retention values (up to 19% and iodine sorption values (up to 31%. Based on the obtained results, it can be concluded that the crystalline structure of cellulose is not significantly changed by periodate oxidation, which is of great importance for textile material production.

  19. Sorption of triazoles to soil and iron minerals.

    Science.gov (United States)

    Jia, Yu; Aagaard, Per; Breedveld, Gijs D

    2007-02-01

    Triazoles, additives in runway de-icers, are found in soil and groundwater at airport sites. To better understand the fate and transport of benzotriazole (BTA) and methylbenzotriazole (MeBTA) and to assess possible remediation options of contaminated groundwater, sorption to various soils and ferrous sorbents has been studied. In batch experiments, limited non-linear sorption of BTA to mineral subsoil from the Oslo International Airport, Gardermoen was observed. The sorption to soil could be described using a Freundlich isotherm. pH affected sorption of BTA to subsoil, although the effect was not strong. Increased sorption was observed to zerovalent iron (Fe(0)). MeBTA showed similar sorption behaviour as BTA although the sorption coefficient was generally higher. Sorption to Fe(0) seems to be controlled by multi-layer coverage. Our data suggest that sorption of triazoles to Fe(2)O(3) is negligible. However BTA sorption to 2-line and 6-line ferrihydrites showed strong sorption. The results demonstrate that triazoles are highly mobile in the subsurface environment, however zerovalent iron can be an effective medium for groundwater remediation. Without remediation, wide distribution of triazoles in the environment can be expected due to its extensive application and limited degradability.

  20. Sorption of Acid Dyes onto Silica Modified with Cetrltrimethylammonium Cations

    Institute of Scientific and Technical Information of China (English)

    TahirImranQureshi; Dong-IkSong; 等

    2002-01-01

    The sorption behavior of acid dyes onto cetyltrimethylammonium bromide (CTAB)-modified silica as a function of pH in the aqueous medium was studied. Single-and multi-solute sorption equilibria of orange Ⅱ(OR), phenol red (PR) and Eriochrome Black T (EBT) were studied at pH 3, unbuffered water pH and pH 11. Sorption behavior of EBT could not be conducted at pH3 due to its aggregation in acidic medium. All the reaction conditions, experimental protocols and techniques remained the same throughout the sorption process. Sorption isotherms for single-solute system were fitted by the Langmuir model, while Langmuir competitive model (LCM) and the ideal adsorbed solution theory (IAST) coupled with Langmuir model (IAST/Langmuir) were used for the prediction of multisolute competitive sorption. Sorption affinities influenced by the factors like physical interactive forces between the molecules of CTA on silica and sorbate, structural limitations of the dyes based on their geometrical arrangement were investigated. Sorption affinity of OR was found to be higher than that of EBT and PR at all the pH values investigated. Magnitude of the sorption capacities was observed to be higher in acidic medium but lower in alkaline medium. Trends of the sorption affinities in multisolute system were simlar to those in single-solute system but magnitude of the sorption capacities was significantly reduced due to the prevailing competition among the sorbates.

  1. PENGERINGAN KEMOREAKSI KULTUR Saccharomyces cerecisiae DENGAN CaO SERTA PENGARUH SORPSI KADAR AIR TERHADAP STRES DAN KEMATIAN KULTUR KERING [Chemoreaction Drying of Saccharomyces cerevisiae Culture with CaO and the Influence of Moisture Sorption Upon Stress and Death of the Dried Culture

    Directory of Open Access Journals (Sweden)

    Susono Saono3

    2005-04-01

    Full Text Available The aim of the research was to study chemoreaction drying of Saccharomyces cerevisiae culture and to a analyze the influence of moisture sorption on pattern of viability, stress and mortality of the dried starter culture.The cell culture of S. cerevisiae was produced in glucose media with aerobic process in a fermentor at 30C. The cell obtained was dried in a using chemoreaction process. Drying was conducted by coating with various thickness of coating and various ratio of CaO and calcium oxide ratio used in drying. Dry culture of S. cerevisiae and protective agent of CMC and jelly were added to the dry culture. The mixtrure then was stored at in decicators at R H 11 up to 97% until water equilibrium was achieved. Later the patterns of stress from each sample of dry culture at various conditions of moisture was analyzed.The result of the research showed that the best drying method was using coat thickness of 1.3 mm and calcium oxide 10 times the weight of dried sample. The condition of dry culture at low minimal water from 5 % were mostly in dormant state, the highest viability was at the rate of moisture of 5 % - 8 %, but a lot portion of the cells were inactive, and at the moisture higher than 8%, dead cells were observed. Addition 2% jelly of 2% CMC did not protect cells from stress.

  2. Experimental study of water desorption isotherms and thin-layer convective drying kinetics of bay laurel leaves

    Science.gov (United States)

    Ghnimi, Thouraya; Hassini, Lamine; Bagane, Mohamed

    2016-02-01

    The aim of this work is to determine the desorption isotherms and the drying kinetics of bay laurel leaves (Laurus Nobilis L.). The desorption isotherms were performed at three temperature levels: 50, 60 and 70 °C and at water activity ranging from 0.057 to 0.88 using the statistic gravimetric method. Five sorption models were used to fit desorption experimental isotherm data. It was found that Kuhn model offers the best fitting of experimental moisture isotherms in the mentioned investigated ranges of temperature and water activity. The Net isosteric heat of water desorption was evaluated using The Clausius-Clapeyron equation and was then best correlated to equilibrium moisture content by the empirical Tsami's equation. Thin layer convective drying curves of bay laurel leaves were obtained for temperatures of 45, 50, 60 and 70 °C, relative humidity of 5, 15, 30 and 45 % and air velocities of 1, 1.5 and 2 m/s. A non linear regression procedure of Levenberg-Marquardt was used to fit drying curves with five semi empirical mathematical models available in the literature, The R2 and χ2 were used to evaluate the goodness of fit of models to data. Based on the experimental drying curves the drying characteristic curve (DCC) has been established and fitted with a third degree polynomial function. It was found that the Midilli Kucuk model was the best semi-empirical model describing thin layer drying kinetics of bay laurel leaves. The bay laurel leaves effective moisture diffusivity and activation energy were also identified.

  3. Experimental study of water desorption isotherms and thin-layer convective drying kinetics of bay laurel leaves

    Science.gov (United States)

    Ghnimi, Thouraya; Hassini, Lamine; Bagane, Mohamed

    2016-12-01

    The aim of this work is to determine the desorption isotherms and the drying kinetics of bay laurel leaves ( Laurus Nobilis L.). The desorption isotherms were performed at three temperature levels: 50, 60 and 70 °C and at water activity ranging from 0.057 to 0.88 using the statistic gravimetric method. Five sorption models were used to fit desorption experimental isotherm data. It was found that Kuhn model offers the best fitting of experimental moisture isotherms in the mentioned investigated ranges of temperature and water activity. The Net isosteric heat of water desorption was evaluated using The Clausius-Clapeyron equation and was then best correlated to equilibrium moisture content by the empirical Tsami's equation. Thin layer convective drying curves of bay laurel leaves were obtained for temperatures of 45, 50, 60 and 70 °C, relative humidity of 5, 15, 30 and 45 % and air velocities of 1, 1.5 and 2 m/s. A non linear regression procedure of Levenberg-Marquardt was used to fit drying curves with five semi empirical mathematical models available in the literature, The R2 and χ2 were used to evaluate the goodness of fit of models to data. Based on the experimental drying curves the drying characteristic curve (DCC) has been established and fitted with a third degree polynomial function. It was found that the Midilli Kucuk model was the best semi-empirical model describing thin layer drying kinetics of bay laurel leaves. The bay laurel leaves effective moisture diffusivity and activation energy were also identified.

  4. Sorption of dyes from aqueous solutions onto fly ash.

    Science.gov (United States)

    Janos, Pavel; Buchtová, Hana; Rýznarová, Milena

    2003-12-01

    Brown coal fly ashes were tested as potentially low-cost sorbents for the removal of synthetic dyes from waters. It was shown that both basic (cationic) as well as acid (anionic) dyes can be sorbed onto the fly ash. The adsorption can be described by the multi-site Langmuir isotherm. The sorption capacities were in the range of 10(-1)-10(-3)mmol/g and did not differ significantly for basic and acid dyes. The dye sorption decreased in the presence of organic solvents (methanol, acetone). The presence of oppositely charged surfactants exhibited a pronounced effect on the dye sorption-low concentrations of the surfactant enhanced sorption, whereas high concentrations solubilized the dyes and kept them in solution. Inorganic salts exhibited only a minor effect on the dye sorption. The sorption of basic dyes increased at high pH values, whereas the opposite was true for acid dyes.

  5. Sorption of tylosin on clay minerals.

    Science.gov (United States)

    Zhang, Qian; Yang, Chen; Huang, Weilin; Dang, Zhi; Shu, Xiaohua

    2013-11-01

    The equilibrium sorption of tylosin (TYL) on kaolinite and montmorillonite was measured at different solution pH using batch reactor systems. The results showed that all the sorption isotherms were nonlinear and that the nonlinearity decreased as the solution pH increased for a given clay. At a specific aqueous concentration, the single-point sorption distribution coefficient (KD) of TYL decreased rapidly as the solution pH increased. A speciation-dependent sorption model that accounted for the contributions of the cationic and neutral forms of TYL fit the data well, suggesting that the sorption may be dominated by both ion exchange and hydrophobic interactions. The isotherm data also fit well to a dual mode model that quantifies the contributions of a site-limiting Langmuir component (ion exchange) and a non-specific linear partitioning component (hydrophobic interactions). X-ray diffraction analyses revealed that the interlayers of montmorillonite were expanded due to the uptake of TYL. TYL molecules likely form a monolayer surface coverage.

  6. Water vapor sorption thermodynamics of the Nafion ionomer membrane.

    Science.gov (United States)

    Wadsö, Lars; Jannasch, Patric

    2013-07-18

    The water interactions of polymer electrolyte membranes are of significant interest when these materials are used in, for example, fuel cells. We have therefore studied the sorption thermodynamics of Nafion with a sorption calorimeter that simultaneously measures the sorption isotherm and the mixing (sorption) enthalpy. This unique method is suitable for investigating the sorption thermodynamics of ionic polymers. The measurements were made at 25 °C on a series of samples dried at different temperatures from 25 to 120 °C. The sorption isotherms indicate that the samples dried at 120 °C lost about 0.8 more water molecules per sulfonic group during the drying than did the samples dried at 25 °C, and this result was verified gravimetrically. The mixing enthalpies showed several peaks or plateaus for the samples dried at 60-120 °C. This behavior was seen up to about 2 water molecules per sulfonic group. As these peaks were not directly related to any feature in the sorption isotherm, they probably have their origin in a secondary process, such as a reorganization of the polymer.

  7. Characteristics of Amine Surfactant Modified Peanut Shell and Its Sorption Property for Cr(VI)

    Institute of Scientific and Technical Information of China (English)

    岳敏; 张猛; 刘斌; 许醒; 李小明; 岳钦艳; 马春元

    2013-01-01

    Modified peanut shell (MPS) was prepared by amination reaction with peanut shell (PS) as the starting material. The sorption of Cr(VI) oxyanions on MPS in static and column tests were investigated. In addition, the sorption isotherm and kinetic models were applied to confirm the sorption capacity and the sorption mechanisms. BET surface area analysis showed the physicochemical characteristics of the samples. The results of zeta potential, Fourier transform infrared (FT-IR) and Raman spectra analysis illustrated that chemical adsorption and ion ex-change are the potential sorption mechanism. The static sorption test showed that the maximum sorption capacity (qmax) of MPS for Cr(VI) increased with temperature, which indicated that the Cr(VI) sorption process was endo-thermic. The saturated sorption capacity of Cr(VI) in the column sorption test was 138.34 mg·g-1, which accounted for 93.9%of the qmax at 25 °C. The regeneration capacity of MPS was evaluated using HCl solution as an eluent. The high regeneration efficiency (82.6%) validated the dominance of the ion exchange mechanism in the Cr(VI) sorption process with Cl-ions displacing Cr(VI) oxyanion on MPS. The Langmuir isotherm model showed a higher correlation coefficient than the other adsorption isotherm models. And in the kinetic study, a pseudo-second-order model fit the data best.

  8. Study of the enthalpy-entropy mechanism from water sorption of orange seeds (C. sinensis cv. Brazilian for the use of agro-industrial residues as a possible source of vegetable oil production

    Directory of Open Access Journals (Sweden)

    Daniele Penteado Rosa

    2013-02-01

    Full Text Available Orange seeds are a promising agroindustry-waste which can be implemented in the extraction and production of vegetable oil. The relationship between moisture content and water activity provides useful information for the processing and storage of this waste item. The aim of this study was to determine the mechanism of water sorption enthalpy-entropy of orange seeds (C. sinensis cv. Brazilians according to the moisture content. Therefore, desorption isotherms were determined at five different temperature (30, 40, 50, 60, and 70 ºC under a wide range of moisture content (0.005-0.057 kg kg-1 d.b. and water activity (0.02-0.756. Theoretical and empirical models were used for modeling the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to compute the isosteric heat of sorption, the differential entropy, and Gibbs free energy using the Oswin model when the effect of temperature on the hygroscopic equilibrium was considered.

  9. Temperature dependence of sorption of gases by coals and charcoals

    Energy Technology Data Exchange (ETDEWEB)

    Sakurovs, Richard; Day, Stuart; Weir, Steve; Duffy, Greg (CSIRO Energy Technology PO Box 330 Newcastle 2300 Australia)

    2008-02-01

    Modelling the sorption properties of coals for carbon dioxide under supercritical conditions is necessary for accurate prediction of the sequestering ability of coals in seams. We present recent data for sorption curves of three dry Argonne Premium coals, for carbon dioxide, methane and nitrogen at two different temperatures at pressures up to 15 MPa. The sorption capacity of coals tends to decrease with increasing temperature. An investigation into literature values for sorption of nitrogen and methane by charcoal also show sorption capacities that decrease dramatically with increasing temperature. This is inconsistent with expectations from Langmuir models of coal sorption, which predict a sorption capacity that is independent of temperature. We have successfully fitted the isotherms using a modified Dubinin-Radushkevich equation that uses gas density rather than pressure. A simple pore-filling model that assumes there is a maximum pore width that can be filled in supercritical conditions and that this maximum pore width decreases with increasing temperature, can explain this temperature dependence of sorption capacity. It can also explain why different supercritical gases give apparently different surface sorption capacities on the same material. The calculated heat of sorption for these gases on these coals is similar to those found for these gases on activated carbon. (author)

  10. Available area isotherm

    NARCIS (Netherlands)

    Bosma, JC; Wesselingh, JA

    2004-01-01

    A new isotherm is presented for adsorption of proteins, the available area isotherm. This isotherm has a steric basis, unlike the (steric) mass action model. The shape of the available area isotherm is determined only by geometric exclusion. With the new isotherm, experimental results can be fitted

  11. Isothermal Sorption of Recycled Aggregate Concrete and Its Influence on Drying Shrinkage%再生骨料混凝土吸湿性能及对干燥收缩的影响

    Institute of Scientific and Technical Information of China (English)

    郭远臣; 王雪; 何运祥

    2012-01-01

    根据孔隙结构理论设计了测量材料润湿性能的装置,测试了再生骨料取代率,减水剂、膨胀剂、粉煤灰掺量对再生骨料混凝土吸湿量的影响曲线,并通过曲线拟合给出不同配合比再生骨料混凝土等温吸湿曲线函数关系式;提出可由初期吸湿曲线来计算材料与水接触角大小,并分析了其对再生骨料混凝土干缩性能的影响.研究表明:再生骨料、减水剂的添加可减小混凝土的接触角,增加混凝土的干缩值;粉煤灰的添加改善了混凝土孔隙结构,能降低与水润湿性,有利于抑制混凝土收缩;减水剂的添加减小了再生骨料混凝土的接触角;膨胀再生混凝土收缩机理不能单用材料润湿性和孔隙结构理论来解释.%Based on pore structure theory, a device for measuring the wetting properties of materials was designed. The effect of recycled aggregate replacement rate, and water reducer, expansive agent, fly ash dosage on isothermal absorption of recycled aggregate concrete was investigated. Through curve fitting, the function relationship of isothermal absorption curve of recycled aggregate concrete with different mix proportion was established. It is proposed that the water contact angle can be calculated from the initial absorption curve, and its impact on drying shrinkage of recycled aggregate concrete is analyzed. Research results show that the addition of recycled aggregate and superplasticizer lowers the contact angle of recycled aggregate concrete, and increases the drying shrinkage. The addition of fly ash improves the pore structure of concrete, and can reduce the wettability, which can help inhibit the shrinkage of recycled aggregate concrete: It is difficult to explain the shrinkage mechanism of expanded recycled concrete only from material wettability and pore structure theory.

  12. Sorption of a nonionic surfactant Tween 80 by minerals and soils.

    Science.gov (United States)

    Kang, Soyoung; Jeong, Hoon Young

    2015-03-02

    Batch experiments were conducted to evaluate Tween 80 sorption by oxides, aluminosilicates, and soils. For oxides, the sorption by silica and alumina follow linear isotherms, and that by hematite follows a Langmuir isotherm. Considering isotherm type and surface coverage, Tween 80 may partition into the silica/alumina-water interface, whereas it may bind to hematite surface sites. Among aluminosilicates, montmorillonite shows the greatest sorption due to the absorption of Tween 80 into interlayers. For other aluminosilicates, it sorbs to surfaces, with the sorption increasing as plagioclaseTween 80 sorption. The greater sorption by untreated soils than H2O2-treated soils indicates that soil organic matter is a vital sorbent. The sorption hysteresis, contributed to by clay minerals and soil organic matter, is characterized by the greater sorption during the desorption than the sorption stages. This suggests the potential difficulty in removing surfactants from soils. Also, sorption of surfactants can adversely affect surfactant-enhanced remediation by decreasing the aquifer permeability and the availability of surfactants for micellar solubilization.

  13. Modeling Fission Product Sorption in Graphite Structures

    Energy Technology Data Exchange (ETDEWEB)

    Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)

    2013-04-08

    The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission

  14. Sorption of organophosphate esters by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wei; Yan, Li [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Duan, Jinming [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jing, Chuanyong, E-mail: cyjing@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2014-05-01

    Graphical abstract: The interfacial interactions between the OPE molecules and CNTs. - Highlights: • Oxygen-containing groups on CNTs change the sorption property for OPEs. • Molecular configuration of OPEs has insignificant impact on their sorption. • Hydrophobic, π–π EDA and Brønsted acid–base interaction occurred between the CNTs and OPEs. - Abstract: Insights from the molecular-level mechanism of sorption of organophosphate esters (OPEs) on carbon nanotubes (CNTs) can further our understanding of the fate and transport of OPEs in the environment. The motivation for our study was to explore the sorption process of OPEs on multi-walled CNTs (MWCNTs), single-walled CNTs (SWCNTs) and their oxidized counterparts (O-MWCNTs and O-SWCNTs), and its molecular mechanism over a wide concentration range. The sorption isotherm results revealed that the hydrophobicity of OPEs dominated their affinities on a given CNT and the π–π electron donor–acceptor (EDA) interaction also played an important role in the sorption of aromatic OPEs. This π–π EDA interaction, verified with Raman and FT-IR spectroscopy, could restrict the radial vibration of SWCNTs and affect the deformation vibration γ(CH) bands of OPE molecules. The OPE surface coverage on CNTs, estimated using the nonlinear Dubinin–Ashtakhov model, indicated that the oxygen-containing functional groups on CNTs could interact with water molecules by H-bonding, resulting in a decrease in effective sorption sites. In addition, FTIR analysis also confirmed the occurrence of Brønsted acid–base interactions between OPEs and surface OH groups of SWCNTs. Our results should provide mechanistic insights into the sorption mechanism of OPE contaminants on CNTs.

  15. Investigation of sorption and migration of {sup 90}Sr on clinoptilolite and mordenite

    Energy Technology Data Exchange (ETDEWEB)

    Minglu Ye; Lu shi jun; Chenkou Quin; Lihong Xu; Adi He; Zhihua Tang [Fudan Univ., Shanghai (China). Dept. of Nuclear Science; Guoqing Xu; Xuanlin Fan; Jifang Gu; Zhichao Du [Beijing Research Inst. of Uranium Geology (BRIUG), BJ (China)

    1998-11-01

    In this work the behaviors of sorption and migration of radioactive strontium on clinoptilolite and mordenite in simulated groundwater has been investigated by both batch technique and column experiment. The sorption ratios (Rd) and the sorption equilibrium time were determined. The effects of particle size of samples, water-to-rock ratios, pH values of simulated groundwater and concentration of strontium in the simulated groundwater on the sorption ratios of Sr were studied. The sorption capacity and sorption isotherm of Sr were determined. The behaviors of sorption and migration of Sr in clinoptilolite column were studied. The migration velocity of Sr was calculated. The results show that sorption abilities of clinoptilolite and mordenite for Sr were very strong. (orig.)

  16. Sorption of polycyclic aromatic hydrocarbons (PAHs) to lignin: effects of hydrophobicity and temperature.

    Science.gov (United States)

    Zhang, Ming; Ahmad, Mahtab; Lee, Sang Soo; Xu, Li Heng; Ok, Yong Sik

    2014-07-01

    The study of the sorption of contaminants to lignin is significant for understanding the migration of contaminants in the environment as well as developing low cost sorbent. In this study, sorption of three polycyclic aromatic hydrocarbons (PAHs), naphthalene, acenaphthene and phenanthrene, to lignin was investigated. Sorption isotherms were well described by both linear and Freundlich sorption models. Sorption coefficients of PAHs to lignin from water obtained from regression of both linear model (K d) and Freundlich model (K f) were highly positively correlated with hydrophobicity of PAHs. The amorphous structure of lignin provided sufficient sorption domain for partitioning of PAHs, and the attraction between PAHs molecules and aromatic fractions in lignin via π-π electron-donor-acceptor (π-π EDA) interaction is hypothesized to provide a strong sorption force. Thermodynamic modeling revealed that sorption of PAHs to lignin was a spontaneous and exothermic process.

  17. Water Diffusion from a Bacterial Cell in Low-Moisture Foods.

    Science.gov (United States)

    Syamaladevi, Roopesh M; Tang, Juming; Zhong, QingPing

    2016-09-01

    We used a Fick's unsteady state diffusion equation to estimate the time required for a single spherical shaped bacterium (assuming Enterococcus faecium as the target microorganism) in low-moisture foods to equilibrate with the environment. We generated water sorption isotherms of freeze-dried E. faecium. The water activity of bacterial cells at given water content increased considerably as temperature increased from 20 to 80 °C, as observed in the sorption isotherms of bacterial cells. When the water vapor diffusion coefficient was assumed as between 10(-12) and 10(-10) m(2) /s for bacterial cells, the predicted equilibration times (teq ) ranged from 8.24×10(-4) to 8.24×10(-2) s. Considering a cell membrane barrier with a lower water diffusion coefficient (10(-15) m(2) /s) around the bacterial cell with a water diffusion coefficient of 10(-12) m(2) /s, the teq predicted using COMSOL Multiphysics program was 3.8×10(-1) s. This result suggests that a single bacterium equilibrates rapidly (within seconds) with change in environmental humidity and temperature.

  18. Sorption equilibrium of mercury onto ground-up tree fern

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Y.-S. [Department of Chemical Engineering, I-Shou University, No. 1, Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung County 840, Taiwan (China)], E-mail: ysho@isu.edu.tw; Wang, C.-C. [Department of Chemical Engineering, I-Shou University, No. 1, Section 1, Hsueh-Cheng Road, Ta-Hsu Hsiang, Kaohsiung County 840, Taiwan (China)

    2008-08-15

    The sorption behavior of mercury at different temperatures onto ground-up tree fern was investigated. The experimental results were fitted to two two-parameter isotherms, the Freundlich and Langmuir isotherms, as well as to two three-parameter isotherms, the Redlich-Peterson and Sips isotherms to obtain the characteristic parameters of each model. A comparison of best-fitting was performed using the coefficient of determination and Chi-square test. Both the Langmuir and Redlich-Peterson isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of mercury ions onto ground-up tree fern was 26.5 mg/g at 298 K. It was noted that an increase in temperature resulted in a higher mercury ion loading per unit weight of the tree fern. In addition, various thermodynamic parameters, such as {delta}G{sup o}, {delta}H{sup o}, and {delta}S{sup o}, were calculated and compared with the sorption of mercury by other sorbents.

  19. Sorption of a nonionic surfactant Tween 80 by minerals and soils

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Soyoung, E-mail: soyoung@pusan.ac.kr; Jeong, Hoon Young, E-mail: hjeong@pusan.ac.kr

    2015-03-02

    Highlights: • Tween 80 sorption varies significantly among soil minerals. • Sorption mechanisms and atomic compositions explain to mineral-specific sorption. • Clay minerals and SOM in soils are the key contributors to Tween 80 sorption. • Hysteresis suggests the potential difficulty in removing residual surfactants. - Abstract: Batch experiments were conducted to evaluate Tween 80 sorption by oxides, aluminosilicates, and soils. For oxides, the sorption by silica and alumina follow linear isotherms, and that by hematite follows a Langmuir isotherm. Considering isotherm type and surface coverage, Tween 80 may partition into the silica/alumina–water interface, whereas it may bind to hematite surface sites. Among aluminosilicates, montmorillonite shows the greatest sorption due to the absorption of Tween 80 into interlayers. For other aluminosilicates, it sorbs to surfaces, with the sorption increasing as plagioclase < vermiculite < kaolinite. This results from the relative reactivity among surface sites: ≡NaOH, ≡CaOH << ≡SiOH < ≡AlOH. Experiments using dry- and wet-sieved soils reveal that fine-grained clay minerals, difficult to separate by dry-sieving, contribute significantly to Tween 80 sorption. The greater sorption by untreated soils than H{sub 2}O{sub 2}-treated soils indicates that soil organic matter is a vital sorbent. The sorption hysteresis, contributed to by clay minerals and soil organic matter, is characterized by the greater sorption during the desorption than the sorption stages. This suggests the potential difficulty in removing surfactants from soils. Also, sorption of surfactants can adversely affect surfactant-enhanced remediation by decreasing the aquifer permeability and the availability of surfactants for micellar solubilization.

  20. Sorption of trace metals on calcite: Applicability of the surface precipitation model

    NARCIS (Netherlands)

    Comans, R.N.J.; Middelburg, J.J.

    1987-01-01

    Published Sorption isotherm data of Cd2+, Mn2+, Zn2+, and Co2+ on calcite are adequately described by the surface precipitation model which was originally developed by FArley et al. (1985) for the sorption of cations on metal oxides. In addition to monolayer adsorption, the model accounts for the fo

  1. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows

  2. Preparation, characterization of electrospun meso-hydroxylapatite nanofibers and their sorptions on Co(II)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hualin, E-mail: hlwang@hfut.edu.cn [School of Chemical Technology, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Peng; Ma, Xingkong; Jiang, Suwei; Huang, Yan; Zhai, Linfeng [School of Chemical Technology, Hefei University of Technology, Hefei, Anhui 230009 (China); Jiang, Shaotong [School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2014-01-30

    Highlights: • PVA/HA nanofibers could change into meso-HA nanofibers by calcination process. • Sorption of Co(II) on meso-HA was strongly dependent on pH and ionic strength. • Sorption kinetic data were well fitted by the pseudo-second-order rate equation. • Sorption isotherms could be well described by the Langmuir model. • Sorption process of Co(II) on meso-HA nanofibers was spontaneous and endothermic. -- Abstract: In this work, mesoporous hydroxylapatite (meso-HA) nanofibers were prepared via calcination process with polyvinyl alcohol/HA (PVA/HA) hybrid nanofibers fabricated by electrospinning technique as precursors, and the removal efficiency of meso-HA nanofibers toward Co(II) was evaluated via sorption kinetics and sorption isotherms. Furthermore, the sorption behaviors of Co(II) on meso-HA nanofibers were explored as a function of pH, ionic strength, and thermodynamic parameters. There existed hydrogen bonds between HA and PVA matrix in precursor nanofibers which could change into meso-HA nanofibers with main pore diameter at 27 nm and specific surface area at 114.26 m{sup 2}/g by calcination process. The sorption of Co(II) on meso-HA was strongly dependent on pH and ionic strength. Outer-sphere surface complexation or ion exchange was the main mechanisms of Co(II) adsorption on meso-HA at low pH, whereas inner-sphere surface complexation was the main adsorption mechanism at high pH. The sorption kinetic data were well fitted by the pseudo-second-order rate equation. The sorption isotherms could be well described by the Langmuir model. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature-dependent sorption isotherms suggested that the sorption process of Co(II) on meso-HA nanofibers was spontaneous and endothermic.

  3. Arsenic sorption onto laterite iron concretions: temperature effect.

    Science.gov (United States)

    Partey, Frederick; Norman, David; Ndur, Samuel; Nartey, Robert

    2008-05-15

    We investigated arsenate and arsenite sorption onto laterite iron concretions (LIC) to test its suitability for use in the low-tech treatment of arsenic-bearing drinking water. Batch experiments on crushed LIC from Prestea, Ghana were conducted at a series of temperatures, ionic strengths, and pHs. The point of zero net charge on laterite iron concretion was determined by potentiometric titrations yielding an average pHp(ZNC) around 8.64. Experiments show that sorption capacity for both arsenite and arsenate increase with temperature. The equilibrium sorption capacity for arsenite was larger than that for arsenate over the 25 to 60 degrees C temperature range. A Langmuir model satisfactorily fits the arsenite and arsenate sorption isotherm data. Both arsenite and arsenate sorbed over the pH range of natural waters. Arsenite sorption increases with increasing solution pH to a maximum at pH 7, then decreases with further increase in solution pH. Arsenate sorption, on the other hand, shows little change with increasing solution pH. Increasing solution ionic strength 10-fold results in a slight increase in sorption. Ionic strength experiments show that an inner-sphere sorption mechanism is responsible for As (V) sorption on LIC, while As (III) sorption is by an outer-sphere mechanism. Gibbs free energy (DeltaG degrees) for arsenite and arsenate sorption onto LIC was calculated from Langmuir isotherms; the negative values agree with reaction spontaneity. The positive values of the standard enthalpy (DeltaH degrees) show the endothermic nature of arsenite and arsenate sorption onto LIC. Positive entropy (DeltaS degrees) values suggest the affinity of LIC for the arsenic species in solution. Analysis of the arsenic sorption data suggests that LIC can be used for low-tech natural-materials arsenic water treatment. Laterite iron concretions have a number of advantages for this use over commercial materials, including the ability to remove arsenic from waters with a wide

  4. Pharmaceuticals' sorptions relative to properties of thirteen different soils.

    Science.gov (United States)

    Kodešová, Radka; Grabic, Roman; Kočárek, Martin; Klement, Aleš; Golovko, Oksana; Fér, Miroslav; Nikodem, Antonín; Jakšík, Ondřej

    2015-04-01

    Transport of human and veterinary pharmaceuticals in soils and consequent ground-water contamination are influenced by many factors, including compound sorption on soil particles. Here we evaluate the sorption isotherms for 7 pharmaceuticals on 13 soils, described by Freundlich equations, and assess the impact of soil properties on various pharmaceuticals' sorption on soils. Sorption of ionizable pharmaceuticals was, in many cases, highly affected by soil pH. The sorption coefficient of sulfamethoxazole was negatively correlated to soil pH, and thus positively related to hydrolytic acidity and exchangeable acidity. Sorption coefficients for clindamycin and clarithromycin were positively related to soil pH and thus negatively related to hydrolytic acidity and exchangeable acidity, and positively related to base cation saturation. The sorption coefficients for the remaining pharmaceuticals (trimethoprim, metoprolol, atenolol, and carbamazepine) were also positively correlated with the base cation saturation and cation exchange capacity. Positive correlations between sorption coefficients and clay content were found for clindamycin, clarithromycin, atenolol, and metoprolol. Positive correlations between sorption coefficients and organic carbon content were obtained for trimethoprim and carbamazepine. Pedotransfer rules for predicting sorption coefficients of various pharmaceuticals included hydrolytic acidity (sulfamethoxazole), organic carbon content (trimethoprimand carbamazepine), base cation saturation (atenolol and metoprolol), exchangeable acidity and clay content (clindamycin), and soil active pH and clay content (clarithromycin). Pedotransfer rules, predicting the Freundlich sorption coefficients, could be applied for prediction of pharmaceutical mobility in soils with similar soil properties. Predicted sorption coefficients together with pharmaceutical half-lives and other imputes (e.g., soil-hydraulic, geological, hydro-geological, climatic) may be used for

  5. Sorption of copper by chemically modified aspen wood fibers.

    Science.gov (United States)

    Huang, Liyuan; Ou, Zhaoyang; Boving, Thomas B; Tyson, Julian; Xing, Baoshan

    2009-08-01

    Sorption of copper (Cu(2+)) by untreated and treated (bleaching and hydrolysis) aspen wood fibers, cellulose and lignin was examined to understand the Cu(2+) sorption behavior by these natural sorbents. All sorbents were characterized by solid-state (13)C NMR and FTIR. Bleaching broke up aromatic structures and increased hydrophilicity of the fibers, whereas hydrolysis decreased carbohydrate content, producing a more hydrophobic structure. Copper sorption was a function of pH; the percentage of Cu(2+) sorption steadily increased from pH 1.5 to 4.5 with a maximum sorption amount at around pH 5.5 for all the materials. All isotherms fitted well to the Langmuir equation. Bleached sample (BL) had a highest sorption capacity, followed by untreated (UTR), cellulose (CEL), and hydrolyzed (HHY), while lignin (LIG) had little Cu(2+) sorption under the studied conditions. The results suggested that carboxyl (-COOH) and hydroxyl (-CHOH) in carbohydrates are mainly responsible for Cu(2+) sorption, and that ion exchange may be a main sorption mechanism for the studied sorbents. Additionally, the sorption capacity for Cu(2+) on all sorbents decreased with the increase of the initial concentrations of Ca(2+), Na(+) or Al(3+). Copper sorption decreased rapidly at low initial concentrations of Ca(2+), Na(+) or Al(3+). However, the decline of Cu(2+) sorption slowed down when initial Na(+) and Ca(2+) concentration was higher than 0.05M or initial Al(3+) concentration was greater than 0.005M, indicating that specific adsorption may be taking place. Therefore, the majority of sorbed Cu(2+) to aspen wood fibers could be through ion exchange (especially, for UTR, BL and CEL), while a faction of sorbed Cu(2+) via inner-sphere complex (or specific adsorption).

  6. Sorption of small molecules in polymeric media

    Science.gov (United States)

    Camboni, Federico; Sokolov, Igor M.

    2016-12-01

    We discuss the sorption of penetrant molecules from the gas phase by a polymeric medium within a model which is very close in spirit to the dual sorption mode model: the penetrant molecules are partly dissolved within the polymeric matrix, partly fill the preexisting voids. The only difference with the initial dual sorption mode situation is the assumption that the two populations of molecules are in equilibrium with each other. Applying basic thermodynamics principles we obtain the dependence of the penetrant concentration on the pressure in the gas phase and find that this is expressed via the Lambert W-function, a different functional form than the one proposed by dual sorption mode model. The Lambert-like isotherms appear universally at low and moderate pressures and originate from the assumption that the internal energy in a polymer-penetrant-void ternary mixture is (in the lowest order) a bilinear form in the concentrations of the three components. Fitting the existing data shows that in the domain of parameters where the dual sorption mode model is typically applied, the Lambert function, which describes the same behavior as the one proposed by the gas-polymer matrix model, fits the data equally well.

  7. Sorption/desorption reversibility of polycyclic aromatic hydrocarbons (PAHs) in soils and carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guohui

    2008-07-01

    Understanding sorption/desorption is an important prerequisite for the prediction of fate and transport of pollutants in the environment. During the last two decades, numerous studies have reported hysteresis phenomenon for the interaction of hydrophobic organic contaminants (HOCs) with natural organic matter (NOM). It manifests as nonsingular sorption/desorption isotherms or different rates for sorption and desorption, where during desorption a higher affinity of a compound on a given sorbent and a longer time scale for release than for sorption is observed. Other studies showed that some of the reported sorption/desorption hysteresis phenomena are due to experimental artifacts, mainly resulting from non-attainment of sorption equilibrium before desorption experiments, which result in 'pseudo-hysteresis'. Except for the hypothesis of sorbent reconfiguration, clear experimental evidence for the physical or chemical mechanisms proposed to lead to hysteresis is still lacking. In this study, sorption/desorption equilibrium and kinetics of phenanthrene sorption/desorption from two soils and three carbonaceous samples were investigated using both batch and column techniques. The main objective of this work was to monitor hysteresis phenomenon by carefully recovering the solute mass in the system and to compare sorption/desorption equilibria and kinetics thermodynamically. Nonsingular isotherms and higher desorption enthalpies as well as increased activation energies with proceeding desorption are expected if significant hysteresis exists. Sorption-desorption cycles were carried out to compare equilibrium isotherms and associated sorption/desorption enthalpies (AeH, isosteric heats). Instead of the traditional decant-and-refill batch method, the experiments were conducted using a newly designed batch protocol, which enables the determination of sorption/desorption isotherms at different temperatures using a closed batch system. This method additionally allows

  8. Sorption of polycyclic aromatic hydrocarbons to polystyrene nanoplastic.

    Science.gov (United States)

    Liu, Lijing; Fokkink, Remco; Koelmans, Albert A

    2016-07-01

    Microplastic has become an emerging contaminant of global concern. Bulk plastic can degrade to form smaller particles down to the nanoscale (nanoplastics. Because of their high surface area, nanoplastic may bind hydrophobic chemicals very effectively, increasing their hazard when such nanoplastics are taken up by biota. The present study reports distribution coefficients for sorption of polycyclic aromatic hydrocarbons (PAHs) to 70 nm polystyrene in freshwater, and PAH adsorption isotherms spanning environmentally realistic aqueous concentrations of 10(-5)  μg/L to 1 μg/L. Nanopolystyrene aggregate state was assessed using dynamic light scattering. The adsorption isotherms were nonlinear, and the distribution coefficients at the lower ends of the isotherms were very high, with values up to 10(9) L/kg. The high and nonlinear sorption was explained from π-π interactions between the planar PAHs and the surface of the aromatic polymer polystyrene and was higher than for micrometer-sized polystyrene. Reduction of nanopolystyrene aggregate sizes had no significant effect on sorption, which suggests that the PAHs could reach the sorption sites on the pristine nanoparticles regardless of the aggregation state. Pre-extraction of the nanopolystyrene with C18 polydimethylsiloxane decreased sorption of PAHs, which could be explained by removal of the most hydrophobic fraction of the nanopolystyrene. Environ Toxicol Chem 2016;35:1650-1655. © 2015 SETAC.

  9. Sorption and desorption of 1,4-dichlorobenzene on peat

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Sorption and desorption of 1,4-dichlorobenzene (DCB) on peat (>92% organic matter)display large-scale hysteresis and nonlinearity. The magnitude of desorption hysteresis decreases in the order: untreated Pahokee peat (P)>acid treated peat (FP)>humin (TP). The desorption percentages are lower than 28% of the sorbed 1, 4-DCB after desorbing for 6 days. The sorption and desorption isotherms are well fitted to Freundlich equation, whose parameter 1/n ranges from 0.055 to 0.527. Moreover, the parameter 1/n of the desorption isotherm is significantly lower than that of the sorption isotherm, but the parameter IogK increases on contrary to 1/n. The desorption isotherms are very well fitted to Langmuir equation, whose Qm decreases in the order: TP>FP>P.The apparent partition coefficients (Kp) increase with increasing sorption time or decreasing aqueous equilibrium concentration of DCB. And Kp of P is significantly higher than that of FP or TP.

  10. Study of adsorption isotherms of green coconut pulp Estudo das isotermas de adsorção da polpa de coco verde

    Directory of Open Access Journals (Sweden)

    Fábia Carolina Gonçalves Lavoyer

    2013-03-01

    Full Text Available Brazil is considered one of the largest producers and consumers of tropical fruits. Green coconut (Cocos nucifera L. stands out not only for its production and consumption, but also for the high amount of waste produced by coconut water industry and in natura consumption. Therefore, there is a need for utilization of this by-product. This study aims to study the adsorption isotherms of green coconut pulp and determine its isosteric heat of sorption. The adsorption isotherms at temperatures of 30, 40, 50, 60, and 70 °C were analyzed, and they exhibit type III behavior, typical of sugar rich foods. The experimental results of equilibrium moisture content were correlated by models present in the literature. The Guggenheim, Anderson and De Boer (GAB model proved particularly good overall agreement with the experimental data. The heat of sorption determined from the adsorption isotherms increased with the decrease in moisture content. The heat of sorption is considered as indicative of intermolecular attractive forces between the sorption sites and water vapor, which is an important factor to predict the shelf life of dried products.O Brasil é considerado um dos maiores produtores e consumidores de frutas tropicais. O coco verde (Cocos nucifera L. se destaca tanto em termos de produção e consumo quanto em quantidade de resíduos gerada por indústrias de água de coco e pelo consumo in natura. Portanto, existe uma necessidade de aproveitamento deste subproduto. Este trabalho teve por objetivo estudar as isotermas de adsorção da polpa de coco verde e determinação do calor isostérico de sorção. As isotermas de adsorção para as temperaturas de 30, 40, 50, 60 e 70 °C foram analisadas e evidenciaram curvas do tipo III, típicas de alimentos ricos em açúcares. Os dados experimentais de umidade de equilíbrio foram correlacionados por modelos da literatura. O modelo de GAB apresentou melhor concordância com os dados experimentais, entre os

  11. Norfloxacin sorption and its thermodynamics on surface-modified carbon nanotubes.

    Science.gov (United States)

    Wang, Zhenyu; Yu, Xiaodong; Pan, Bo; Xing, Baoshan

    2010-02-01

    Adsorption on carbon nanotubes (CNTs) may affect the environmental behavior of organic contaminants including antibiotics. In this study, sorption of norfloxacin (NOR) onto graphitized multiwall CNTs (G-CNTs), carboxylated multiwall CNTs (C-CNTs), hydroxylated multiwall CNTs (H-CNTs), and activated carbon (AC) was investigated. All sorption isotherms were highly nonlinear and were fitted well by Freundlich and Polanyi-Manes models. AC showed the highest NOR sorption capacity because of its highest surface area. H-CNTs had much higher NOR sorption than C-CNTs, and the pi-pi electron donor-acceptor (EDA) interactions could explain the distinction between the two types of CNTs. Comparison of sorption coefficients at different pHs indicates that hydrophobic and electrostatic interaction also played major roles in sorption of NOR on CNTs. Furthermore, high sorption capacity and hysteresis of NOR on CNTs were demonstrated in this study, which needs to be considered for predicting environmental risks of CNTs and NOR. The results from thermodynamic analysis show that sorption of NOR on AC and CNTs was thermodynamically favorable and generally endothermic. Sorption site energy analysis illustrates a distribution of sorption energy, consistent with nonlinear isotherms, which indicates the heterogeneous sites on CNTs for NOR adsorption.

  12. Competitive sorption of cadmium and lead in acid soils of central Spain

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, S.; Garrido, F.; Campbell, C.G.; Garcia-Gonzolez, Maria Teresa

    2004-01-30

    The bioavailability and ultimate fate of heavy metals in the environment are controlled by chemical sorption. To assess competitive sorption of Pb and Cd, batch equilibrium experiments (generating sorption isotherms) and kinetics sorption studies were performed using single and binary metal solutions in surface samples of four soils from central Spain. For comparisons between soils, as well as, single and binary metal solutions, soil chemical processes were characterized using the Langmuir equation, ionic strength, and an empirical power function for kinetic sorption. In addition, soil pH and clay mineralogy were used to explain observed sorption processes. Sorption isotherms were well described by the Langmuir equation and the sorption kinetics were well described by an empirical power function within the reaction times in this study. Soils with higher pH and clay content (characterized by having smectite) had the greatest sorption capacity as estimated by the maximum sorption parameter (Q) of the Langmuir equation. All soils exhibited greater sorption capacity for Pb than Cd and the presence of both metals reduced the tendency for either to be sorbed although Cd sorption was affected to a greater extent than that of Pb. The Langmuir binding strength parameter (k) was always greater for Pb than for Cd. However, these k values tended to increase as a result of the simultaneous presence of both metals, that may indicate competition for sorption sites promoting the retention of both metals on more specific sorption sites. The kinetic experiments showed that Pb sorption is initially faster than Cd sorption from both single and binary solutions although the simultaneous presence of both metals affected the sorption of Cd at short times while only a minor effect was observed on Pb. The estimated exponents of the kinetic function were in all cases smaller for Pb than for Cd, likely due to diffusion processes into micropores or interlayer space of the clay minerals which

  13. Comparative equilibrium studies of sorption of Pb(II) ions by sodium and calcium alginate

    Institute of Scientific and Technical Information of China (English)

    KHOTIMCHENKO Maxim; KOVALEV Valeri; KHOTIMCHENKO Yuri

    2008-01-01

    The absorption of Pb(II) ions from aqueous solution by different alginate compounds was studied in a batch sorption system. Water soluble sodium alginate and insoluble calcium alginate beads were investigated. The lead-binding capacity of both alginate compounds was highest within the pH range 6-8. The binding capacities and rates of Pb(II) ions by alginate compounds were evaluated. The Langmuir, Freundlich and Bruneaur, Emmet and Teller (BET) sorption models were applied to describe the isotherms and isotherm constants. Sorption isothermal data could be well interpreted by the Langmuir model. The results obtained through the study suggest that alginate compounds are favorable sorbents. The largest amount of Pb(II) ions were bound by sodium alginate although the difference between two compounds was slight. Therefore, alginate substances may be considered as alternative for sorption and removal of Pb(II) ions from wastewaters.

  14. WATER SORPTION PROPERTIES AND ANTIMICROBIAL ACTION OF ZINC OXIDE NANO PARTICLES LOADED SAGO STARCH FILM

    Directory of Open Access Journals (Sweden)

    Sunil Bajpai

    2013-02-01

    Full Text Available In this work, sago starch based films have been loaded with ZnO nanoparticles prepared insitu via using an unique equilibration-cum-hydrothermal approach. The films have been characterized by XRD, DSC,SPR ,FTIR and SEM analysis. The moisture absorption behavior of plain and ZnO nanoparticles loaded films have been studied at 23, 31 and 37o C.The equilibrium moisture uptake data was found to fit well on GAB isotherm model and the monolayer sorption capacity Mo for the plain and ZnO nanoparticles loaded films was 0.089, 0.039 ,0.021 g/g and 0.042, 0.012, 0.007 g/g at 23,31 and 37 oC respectively. Moreover, the water vapor transmission rates (WVTR for plain and ZnO nanoparticles loaded films at 23,31,37 oC were 11.19x10-4, 48.9x10-4, 62.1x10-4 and 3.73 x10-4, 6.21x10-4, 24.8x10-4 respectively. These films have shown excellent antibacterial action against model bacteria E.coli when investigated qualitatively by zone inhibition method. Films exhibit great potential to be used as packaging films to protect food stuff against microbial contaminents.

  15. Cadmium sorption in solution by a chitin: effect of pH; Sorption du cadmium en solution par une chitine: effet du pH

    Energy Technology Data Exchange (ETDEWEB)

    Benguella, B.; Benaissa, H. [Universtie de Tlemcen, Lab. de Materiaux Sorbants et Traitement des Eaux, Dept. de Chimie, Faculte des Sciences, Tlemcen (Algeria)

    2001-07-01

    The pH is an essential factor to take into consideration in the sorption mechanisms of metals: it acts both on the metal speciation in solution and on the chemical behaviour of the surface of the sorbing material, and thus indirectly on the sorption mechanism. The effect of the initial pH of the solution on the cadmium sorption by raw state chitin has been studied in static conditions. The approach used is the determination of the sorption kinetics and equilibria for different values of initial pH (pH < 7-7.5). An increase of the initial pH value of the solution leads to an increase of the cadmium sorption capacity by chitin at the equilibrium. The Langmuir model has revealed to be convenient for a mathematical description of the sorption isotherms obtained. (J.S.)

  16. Kinetic Model of the Sorption of Cu2+ and Pb2+ From Aqueous Solution Using Carbonized Treculia Africana Husk as Biomass

    OpenAIRE

    , A.K. Asiagwu; , P.E Omuku; , J.I. Odiachi; , V.N. Okafor

    2016-01-01

    The sorption kinetics of model (Cu2+ and Pb“) from aqueous solution using carbonized Africana brad fruit (Treculia Africana) husk was investigated. The effect of contact time, variation in mass and particle size of adsorbent and adsorption isotherms were studied. The time-dependent experiment showed rapid sorption between 15-30 minutes with maximum sorption at 30mins, after which the rate of adsorption became almost constant. The sorption capacity is dependent on its particle size. A particle...

  17. Application of Humidity-Controlled Dynamic Mechanical Analysis (DMA-RH to Moisture-Sensitive Edible Casein Films for Use in Food Packaging

    Directory of Open Access Journals (Sweden)

    Laetitia M. Bonnaillie

    2015-01-01

    Full Text Available Protein-based and other hydrophilic thin films are promising materials for the manufacture of edible food packaging and other food and non-food applications. Calcium caseinate (CaCas films are highly hygroscopic and physical characterization under broad environmental conditions is critical to application development and film optimization. A new technology, humidity-controlled dynamic mechanical analysis (DMA-RH was explored to characterize CaCas/glycerol films (3:1 ratio during isohume temperature (T ramps and steps, and isothermal RH ramps and steps, to determine their mechanical and moisture-sorption properties during extensive T and RH variations. When RH and/or T increased, CaCas/Gly films became strongly plasticized and underwent several primary and secondary humidity-dependent transition temperatures (or transition humidities; the CaCas/Gly network hypothetically rearranged itself to adapt to the increased water-content and heat-induced molecular mobility. Between 5–40 °C and 20%–61% RH, moisture-sorption was rapid and proportional to humidity between transition points and accelerated greatly during transitions. CaCas/Gly films seemed unsuitable for storage or utilization in warm/humid conditions as they lost their mechanical integrity around Tm ~ 40 °C at 50% RH and Tm decreased greatly with increased RH. However, below Tm, both moisture- and heat-induced structural changes in the films were fully reversible and casein films may withstand a variety of moderate abuse conditions.

  18. Separation of (+)-catechin and quercetin on mesoporous MCM-41 composites: Dynamics of the sorption of flavonoids

    Science.gov (United States)

    Karpov, S. I.; Korabel'nikova, E. O.

    2015-06-01

    An analysis of conditions for chromatographic separation of quercetin and (+)-catechin based on experimental data and using the equations of an asymptotic model of sorption dynamics for substances characterized by convex isotherms of sorption is presented. The effects of the equilibrium (distribution coefficient) and kinetic (diffusion coefficient) factors on the dynamics of the sorption of flavonoids by ordered mesoporous material of the MCM-41 type and its composites with grafted organosilane groups is considered. The effects of kinetic and equilibrium parameters on the broadening of adsorption fronts is demonstrated with allowance for the inner and outer diffusion limitations of the sorption process.

  19. Sorption of cesium ions by nanostructured calcium aluminosilicates

    Science.gov (United States)

    Gordienko, P. S.; Shabalin, I. A.; Yarusova, S. B.; Suponina, A. P.; Zhevtun, I. G.

    2016-10-01

    Data on the sorption properties of synthetic calcium aluminosilicates (CASes) with Al: Si ratios of 2: 2, 2: 6, and 2: 10, fabricated within the multicomponent system CaCl2-AlCl3-KOM-SiO2-H2O, are presented. Isotherms of the sorption of Cs+ ions from aqueous solutions with Cs+ concentrations of 0.2 to 6.0 mmol L-1 are analyzed. The CAS maximum sorption capacity and the Langmuir constants are determined. Kinetic data are obtained, and the energy of cation-exchange activation upon the sorption of Cs+ ions is determined. The effect of a salt background (1% KCl + 6% NaCl) has on the values of distribution coefficient ( K d) and the degree of Cs+ ion removal is established.

  20. Moisture in organic coatings - a review

    NARCIS (Netherlands)

    Wel, G.K. van der; Adan, O.C.G.

    1999-01-01

    A review is given on transport and equilibrium sorption of moisture in polymer films and organic coatings. Polymeric material forms the continuous phase of a coating and is therefore important for transport properties. Besides polymer, coatings consist of pigments and fillers and various additives,

  1. Moisture in organic coatings - a review

    NARCIS (Netherlands)

    Wel, G.K. van der; Adan, O.C.G.

    1999-01-01

    A review is given on transport and equilibrium sorption of moisture in polymer films and organic coatings. Polymeric material forms the continuous phase of a coating and is therefore important for transport properties. Besides polymer, coatings consist of pigments and fillers and various additives,

  2. Effect of moisture content on selected physicochemical properties of two commercial hen egg white powders.

    Science.gov (United States)

    Rao, Qinchun; Labuza, Theodore P

    2012-05-01

    After short-term storage at 23°C, selected physicochemical properties of two hen egg white powders (with and without hydrolysis) were studied. Overall, the effect of moisture content on physicochemical properties of Hydrolysed Egg White powder (HEW) was more severe than those of Dried Egg White powder (DEW). The denaturation temperature (Td) and its enthalpy change (ΔHd) of ovalbumin in DEW followed an exponential model, as well as the Td of HEW. The Gordon-Taylor equation modelled well the glass transition temperatures (Tg) of HEW and DEW. The Guggenheim-Anderson-de Boer (GAB) model fitted well to the type II moisture sorption isotherm. At the critical moisture content (12.0%, dry basis), compared with DEW, the colour of HEW began to darken dramatically and its hardness started to change significantly. These changes were closely related to the inherent characteristics of the two products. The mechanisms relevant to these physicochemical changes were discussed. Published by Elsevier Ltd.

  3. Water vapor sorption hysteresis of ceramic bricks

    Science.gov (United States)

    Koronthalyova, Olga

    2016-07-01

    A quantification of the hysteretic effects and their thorough analysis was carried out for three types of ceramic bricks. Water vapor adsorption/desorption isotherms were measured by the standard desiccator method. The desorption measurements were carried out from capillary moisture content as well as from equilibrium moisture content corresponding to the relative humidity of 98 %. For all three tested types of bricks the hysteretic effects were present but their significance differed depending on the particular type of brick. Significant differences were noticed also in desorption curves determined from capillary moisture content and from equilibrium moisture content corresponding to the relative humidity of 98 %. Based on the measured data a possible correlation between pore structure parameters and noticed hysteretic effects as well as relevance of the open pore model are discussed. The obtained adsorption/desorption curves were approximated by an analytical relation.

  4. Sorption of metals by Chlorobium spp.

    Science.gov (United States)

    Garcia-Gil, J; Borrego, C

    1997-12-01

    The capacity of two species of green phototrophic sulfur bacteria, Chlorobium limicola and C. phaeobacteroides, to sorb several metal ions (Mn2+, Fe2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+) has been tested in laboratory batch cultures at increasing concentrations up to 2,000 mumol/l. Except for nickel--which was not sorbed to bacterial cells--the rest of metals tested were bound in a fast and passive process, which was mathematically described by means of Freundlich isotherms models. The sorption capacity of the two species studied were found to be dependent on the metal involved, whereas no differences were observed in the sorption intensity, suggesting that in all cases the sorption process proceeds in a similar way. Further, the comparison of the sorption intensity values as well as the metal recovery index (Ri), for both species, revealed that C. phaeobacteroides was more efficient that C. limicola to attach metal ions. The ecological significance of this ability in the water column of some stratified lakes, where coinciding maxima of ferrous iron and green photosynthetic sulfur bacteria are frequently found, is discussed.

  5. Equilibrium, kinetic and thermodynamic studies for sorption of Ni (II) from aqueous solution using formaldehyde treated waste tea leaves

    OpenAIRE

    2015-01-01

    The sorption characteristic of Ni (II) from aqueous solution using formaldehyde treated waste tea leaves as a low cost sorbent has been studied. The effect of pH, contact time, sorbent dose, initial metal ion concentration and temperature were investigated in batch experiments. The equilibrium data were fitted into four most common isotherm models; Freundlich, Langmuir, Tempkin and Dubinin–Radushkevich (D–R). The Langmuir model described the sorption isotherm best with maximum monolayer sorpt...

  6. Synthesis, characterization and trivalent arsenic sorption potential of Ce-Al nanostructured mixed oxide

    Science.gov (United States)

    Bhattacharya, S.; Gupta, K.; Ghosh, U. C.

    2017-04-01

    Arsenic contamination in the ground water has serious health consequences in many parts of the world. The surface sorption method for arsenic mitigation has been widely investigated due to its simple method, inexpensive operation, highly efficient and low content of by-products. In the present study, nanostructured hydrated cerium aluminum oxide (NHCAO) was synthesized and characterized and its arsenic (III) sorption behavior from the aqueous solution was studied. The material was characterized in SEM, FE-SEM, TEM, AFM, XRD, and FT-IR. Batch method was used for the kinetics of As (III) sorption on nanoparticles at 303 (± 1.6) K and at pH 7.0 (± 0.2). The experiments on isotherm subject were performed individually at 288K, 303K, 318K temperatures at pH 7.0 (± 0.2) using the batch sorption method. In the kinetics study of arsenic (III) sorption, the sorption percentage was observed to remain nearly unchanged up to pH 9.0, thereafter only slight reduction in sorption percentage. The equilibrium sorption results were tested using the models of Langmuir and the Freundlich isotherm. The Langmuir model is the most fitted model for the sorption reaction. NHCAO was highly efficient in As(III) removal out of the water in the extensive range of pH and could be used for arsenic removal from contaminated water.

  7. Isothermal, kinetic and thermodynamic studies on basic dye sorption ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-12-15

    Dec 15, 2009 ... obtained by diluting the dye stock solutions in accurate proportions to different ... with a 752 W Grating Spectrophotometer (Shanghai, China) and computing from the ... The ion exchange mechanism could be used to explain.

  8. Study on sorption of D155 resin for gadolinium

    Institute of Scientific and Technical Information of China (English)

    XIONG Chunhua

    2008-01-01

    The sorption behavior and mechanism of a Macroporous weak acid resin,(D155 resin,)for Gd(III) were investigated. The statically saturated sorption capacity is 283 mg/g resin at 298 K in HAc-NaAc medium. The Gd(III) adsorbed on macroporous weak acid resin,(D155 resin,)could be reductively eluted with the mixed solution of HCl and NaCl, and the elution percentage was as high as 100%. The resin could be regenerated and reused without remarkable decrease in sorption capacity. The apparent sorption rate constant was k298=1.98×10-5 s-1. The apparent activation energy was Ea=2.78 kJ/mol. The sorption behavior of D155 resin for Gd(III) obeyed the Langmuir isotherm. The thermodynamic sorption parameters were (H=33.0 kJ/mol, (S=192 J/mol/K, and (G298=-24.3 kJ/mol. The sorption mechanism of D155 resin for Gd(III) was examined by using chemical method and IR spectrometry. The coordination compound was formed between oxygen atoms in the functional group of D155 resin and Gd (III).

  9. Studying the sorption properties of a clinoptilolite-containing tuff with respect to europium(III) ions

    Science.gov (United States)

    Kozhevnikova, N. M.

    2014-03-01

    The kinetic laws of sorption of europium(III) ions from sulfate solutions by a clinoptilolite-containing tuff are studied. The kinetic parameters of sorption process are determined and absorption isotherms are constructed for europium ions. It is found that both external and internal diffusion are rate-limiting steps, and europium is completely extracted from dilute solutions (<0.0025 m).

  10. Hygrothermal Properties of Cross Laminated Timber and Moisture Response of Wood at High Relative Humidity

    Science.gov (United States)

    AlSayegh, George

    Cross Laminated Timber (CLT) is a new wood-based material composed of cross laminated wood boards that form a structural panel. This study focuses on identifying the appropriate methods to determine the hygrothermal properties of CLTs fabricated with Canadian and European Lumber. The laboratory tests carried out in this study will help establish heat, air and moisture response properties to be used for hygrothermal simulation to assess the durability of CLTs in building envelope construction. Measurement of water vapour permeability, liquid water absorption, sorption isotherms, thermal conductivity, and air permeability were performed on three Canadian CLT specimens composed of Hem-Fir, Eastern Spruce-Pine-Fir, and Western Spruce-Pine-Fir and one European specimen composed of Spruce. The hygrothermal properties of CLT, considered in this study, appear to be similar to commonly used wood specimens reported in the literature. However, liquid water absorption coefficients of CLT were found to be generally lower than common wood species, possibly due to the presence of glue between the wood layers which limits the moisture movement across the specimen. On the other hand, the air permeability across the CLT specimens varied due to the glue discontinuity within the specimen which led some CLTs to be permeable, however all the European specimens were found to be impermeable. This study also critically analyzed the significance of equilibrium moisture content (EMC) of wood at high relative humidity, measured by means of a pressure plate apparatus and humidity chambers, on the moisture management performance of a wood-frame stucco wall, using the hygrothermal simulation tool hygIRC-2D. The simulation results indicate that the prediction of the moisture response of a wood-frame stucco wall assembly depends significantly on the method adopted to derive the EMC of wood at high RH.

  11. Sorption of toxic organic compounds on wastewater solids: Mechanism and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.; Govind, R.; Dobbs, R.A.

    1992-01-01

    Sorption of toxic organic compounds on wastewater solids is an important process in conventional biological wastewater treatment systems. The extent of accumulation of toxic organic compounds by sorption onto wastewater solids not only affects the efficiency of the treatment system, but also impacts the management of wastewater solids. The study is an attempt to propose a mechanism for understanding the sorption phenomenon and to develop a model for sorption on wastewater solids based on the proposed mechanism. It was postulated that sorption was a combination of two processes: adsorption and partitioning. A sorption model was developed for both single component and multicomponent systems. The model was tested using single component experimental isotherm data of eight toxic organic compounds.

  12. A comparative study of phosphate sorption in lowland soils under oxic and anoxic conditions

    DEFF Research Database (Denmark)

    Heiberg, Lisa; Pedersen, Thomas Vils; Jensen, Henning S.;

    2010-01-01

    of 36 to 93% of the dithionite-extractable FeIII (FeBD). Langmuir fitted Pi sorption isotherms showed a Pi release of up to 1.1 mmol kg-1 in six soils when Pi concentrations in the matrix (Psol) were lower than 10 µM. Phosphate desorption was attributed to dissolution of amorphous iron oxides......Received for publication June 13, 2009. Phosphate (Pi) release due to FeIII oxide dissolution is well documented for soils undergoing reduction. The Pi sorption properties of soils in anoxic conditions are, however, still under consideration. In this investigation, Pi sorption to strictly anoxic...... FeII phosphates may have caused the higher sorption capacities. Use of maximum sorption capacity (Smax) is therefore misleading as a measure of Pi sorption at low Psol concentrations. The results demonstrate that none of the strongly anoxic soils, irrespective of the initial FeIII oxide content...

  13. Enhanced sorption of polycyclic aromatic hydrocarbons from aqueous solution by modified pine bark.

    Science.gov (United States)

    Li, Yungui; Chen, Baoliang; Zhu, Lizhong

    2010-10-01

    To enhance removal efficiency of natural sorbent with polycyclic aromatic hydrocarbons (PAHs), single-solute and bi-solute sorption of phenanthrene and pyrene onto raw and modified pine bark were investigated. Pine bark was modified using Soxhlet extraction, saponification and acid hydrolysis, yielding six bark fractions with different chemical compositions. Raw pine bark exhibited high affinities with PAHs, and sorption was dominated by partitioning. The relatively nonlinear sorption isotherms of modified bark were attributed to the specific interaction between sorbate and aromatic core of sorbent. Comparison with lipid and suberin, lignin was the most powerful sorption medium, but which was almost completely suppressed by coexisting polysaccharide. After consuming polysaccharide by acid hydrolysis, sorption of pine bark fractions was notably increased (4-17 folds); and sorption of pyrene just decreased 16-34% with phenanthrene as a competitor. These observations suggest that pine bark is of great potential for PAHs removal and can be significantly promoted by acid hydrolysis for environmental application.

  14. Sorption and transport of atrazine in an agricultural soil

    Science.gov (United States)

    Hakan Akyol, Nihat

    2014-05-01

    Sorption and transport of atrazine in an agricultural soil Atrazine is one of the most commonly used herbicides in large quantity worldwide. The objective of this study was to perform some batch and column experiments to examine the transport of atrazine in an agricultural soil from Turkey. Batch experiments indicated that sorption isotherm was nonlinear with a freundlich isotherm over a range of concentration (0.2-10 mg/L) examined. Column experiments showed that transport of atrazine in the soil was moderately retarded compared to non-reactive tracer (R = 2.9-4.0). The degree of retardation decreased with increasing atrazine concentration and residance time had negligable impact on degree of sorption. Flow interruption tests in the column experiments indicated that the rate-limited desorption of atrazine mainly controlled the non-ideal transport of atrazine due to the presence of organic matter fraction (0.83 %) in the soil. Sorption and desorption behavior of atrazine in such soils could have important impacts for risk assessment of atrazine-contaminated soil and should be taken into account in the regulation, management, and remediation of atrazine-contaminated sites. Keywords: Atrazine, Agricultural soil, Batch, Column, Desorption, Rate-limited desorption, Sorption, Transport.

  15. Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

    Science.gov (United States)

    Evans, K.; Ferris, F.

    2009-05-01

    At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

  16. moisture transfer

    Directory of Open Access Journals (Sweden)

    Don Kulasiri

    2005-01-01

    model drying porous materials. Coupled partial differential equations governing the moisture and heat transfer can be solved using numerical techniques, and in this paper we solve them analytically in a setting suitable for industrial drying situations. We discuss the nature of the solutions using the physical properties of Pinus radiata. It is shown that the temperature gradients play a significant role in deciding the moisture profiles within the material when thickness is large and that models based only on moisture potential gradients may not be sufficient to explain the drying phenomena in moist porous materials.

  17. Impact of Wood Species, Dimensions and Drying Temperature on Sorption Behaviour of Wood

    Directory of Open Access Journals (Sweden)

    Darius Albrektas

    2015-04-01

    Full Text Available This research paper examines the interdependence between wood sorption properties and its dimensions, species and drying temperature. The research was carried out on specimens of six species of wood (oak, ash, aspen, birch, spruce and pine which had different dimensions and were dried at temperatures ranging between 30 and 90 °C. Subsequently specimens underwent the moistening and air drying process, and the following parameters were recorded: moistening and drying rate, moisture content distribution, steady moisture content and sorption hysteresis. It was established that sorption hysteresis was most affected by the cross section dimensions of the specimen. It was determined that, when the thickness of wood specimens increases from 7 to 30 mm, sorption hysteresis grows up to 8 times. The steady moisture content depends on the density, measurements and drying temperature of the specimen.

  18. The Effect of Temperature on Moisture Transport in Concrete.

    Science.gov (United States)

    Wang, Yao; Xi, Yunping

    2017-08-09

    Most concrete structures and buildings are under temperature and moisture variations simultaneously. Thus, the moisture transport in concrete is driven by the moisture gradient as well as the temperature gradient. This paper presents an experimental approach for determining the effect of different temperature gradients on moisture distribution profiles in concrete. The effect of elevated temperatures under isothermal conditions on the moisture transport was also evaluated, and found not to be significant. The non-isothermal tests show that the temperature gradient accelerates the moisture transport in concrete. The part of increased moisture transfer due to the temperature gradient can be quantified by a coupling parameter DHT, which can be determined by the present test data. The test results indicated that DHT is not a constant but increases linearly with the temperature variation. A material model was developed for DHT based on the experimental results obtained in this study.

  19. Tungsten removal from molybdate solutions using chelating ion-exchange resin:Equilibrium adsorption isotherm and kinetics

    Institute of Scientific and Technical Information of China (English)

    朱先正; 霍广生; 倪捷; 宋琼

    2016-01-01

    The equilibrium adsorption isotherm and kinetic of the sorption process for W and Mo on macro chelating resin D403 were investigated on single Na2MoO4 and Na2WO4 solutions. The sorption isotherm results show that the adsorption process of W obeys the Freundlich model very well whereas the exchange process with Mo approximately follows the Henry model. The kinetic experiments show that the intraparticle diffusion process was the rate-determining step for W sorption on the resin, and the corresponding activation energy is calculated to be 21.976 kJ/mol.

  20. Sorption properties of wool

    Directory of Open Access Journals (Sweden)

    Radetić Maja M.

    2004-01-01

    Full Text Available Strict ecological legislation, especially in highly developed countries, imposed requirements for the purification of industrial effluents and the need for efficient oil clean up after sea and inland water spills. Although numerous processes have been developed, the application of sorbents is still one of the most efficient methods to remove heavy metal ions, dyes and crude oil from water. Recently, special attention was paid to sorbents based on natural fibres. A review of studies concerning the sorption properties of wool is presented in this paper. The presence of various functional groups on the wool fibre surface contributes to the efficient sorption of heavy metal ions and dyes. A hydrophobic, scaly surface and fibre crimp strongly influence the high sorption capacity of wool for oil. Wool has great sorption potential even as a recycled material. Accordingly, it can be used as a viable substitute to commercially available synthetic sorbents that show poor biodegradab ility.

  1. Long-term tillage effects on soil metolachlor sorption and desorption behavior.

    Science.gov (United States)

    Ding, Guangwei; Novak, Jeffrey M; Herbert, Stephen; Xing, Baoshan

    2002-09-01

    Sorption and desorption are two important processes that influence the amount of pesticides retained by soils. However, the detailed sorption mechanisms as influenced by soil tillage management are unclear. This study examined the sorption and desorption characteristics of metolachlor [2-chloro-N-(2-ethyl-6-methyphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] using the soil samples collected from the long-term conservation tillage (CnT) and conventional tillage (CT) research plots established in 1979 in Darlinton, SC. Humic acid (HA) and humin were extracted from the soils and used in the sorption experiments along with the whole soil samples. The sorption experiments were conducted using a batch-equilibration method. Three sequential desorption rinses were carried out following the sorption experiments. By comparing metolachlor sorption and desorption results we observed hysteresis for all soil samples and their organic matter fractions. Sorption nonlinearity (N) and hysteresis were dependent on the structure and composition of soil organic matter (SOM), e.g., Freundlich isotherm exponents (N) of HA and humin from CnT were higher than those of CT treatment, which may be related to high aromaticity of SOM fractions in CT treatment. Sorption capacity (K'f) was positively correlated with soil organic carbon (SOC) content. These results show that long-term tillage management can greatly affect metolachlor sorption and desorption behavior probably by qualitative differences in the structural characteristics of the humic substances.

  2. Impact of coal structural heterogeneity on the nonideal sorption of organic contaminants.

    Science.gov (United States)

    Shi, Xin; Fu, Heyun; Li, Yuan; Mao, Jingdong; Zheng, Shourong; Zhu, Dongqiang

    2011-06-01

    Carbonaceous geosorbents (black carbon, coal, and humin/kerogen) play a primary role in the nonideal sorption (isotherm nonlinearity, hysteresis, and multiphasic kinetics) of hydrophobic organic chemicals by soils and sediments. The present study investigated the impact of coal structural heterogeneity on sorption/desorption of two model monoaromatic compounds (1,3-dichlorobenzene and 1,3-dinitrobenzene). Due to the higher degree of aromaticity and condensation, anthracite showed stronger sorption affinity and nonlinearity and slower sorption kinetics than lignite. Removal of humic substances by alkali extraction and/or mineral fraction by acidification did not much affect organic carbon-normalized sorption coefficient to the coal, suggesting nearly complete accessibility of adsorption sites on the condensed organic carbon. However, the treatments greatly increased sorption kinetics and meanwhile alleviated hysteresis of 1,3-dinitrobenzene, as compared with the original lignite. These observations were attributed to the enhanced exposure of high-energy adsorption sites on the condensed organic carbon after exfoliating the surface coverage by humic substances and minerals. An empirical biphasic pseudo-second-order model consisting of a fast sorption phase and a slow sorption phase adequately quantified the overall sorption kinetics for the coal sorbents. The results indicated that the condensed organic carbon, in combination with other structural components, controls the nonideal sorption of unburned coal. Copyright © 2011 SETAC.

  3. Isothermal and Adiabatic Measurements.

    Science.gov (United States)

    McNairy, William W.

    1996-01-01

    Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)

  4. Enthalpy-entropy compensation based on isotherms of mango Compensação entalpia-entropia baseada nas isotermas de mango

    Directory of Open Access Journals (Sweden)

    Javier Telis-Romero

    2005-06-01

    Full Text Available Moisture equilibrium data of mango pulp were determined using the static gravimetric method. Adsorption and desorption isotherms were obtained in the range of 30-70 ºC, to water activities (a w from 0.02 to 0.97. The application of the GAB model to the experimental results, using direct nonlinear regression analysis, provided agreement between experimental and calculated values. The net isosteric heat of sorption was estimated from equilibrium sorption data, using the Clausius-Clapeyron equation. Isosteric heats of sorption were found to increase with increasing temperature and could be well adjusted by an exponential relationship. The enthalpy-entropy compensation theory was applied to sorption isotherms and plots of deltaH versus deltaS provided the isokinetic temperatures, indicating an enthalpy controlled sorption process.Dados de equilíbrio da umidade da polpa de manga foram determinados utilizando-se o método estático gravimétrico. As isotermas de adsorção e dessorção foram obtidas na faixa de 30-70 ºC e as atividades de água (a w de 0,02 a 0,97. A utilização do modelo de GAB nos resultados experimentais, através da análise de regressão não linear, proporcionou um bom ajuste entre os dados experimentais e os valores calculados. O calor isostérico de sorção foi estimado a partir dos dados de equilíbrio de sorção, utilizando-se a equação de Clausius-Clayperon. Notou-se que os calores isostéricos de sorção crescem com o aumento da temperatura e pode ser bem ajustado através de uma relação exponencial. A teoria da compensação entalpia-entropia foi aplicada às isotermas de sorção e gráficos deltaH versus deltaS forneceram as temperaturas isocinéticas, indicando um processo de sorção entalpicamente controlado.

  5. SORPTION OF PHENOL ONTO GEL—TYPE CROSSLINKED POLYSTYRENEISOCYANURIC ACID RESIN

    Institute of Scientific and Technical Information of China (English)

    XUMancai; SHIZuoqing; 等

    2000-01-01

    Spherical crosslinked polystyrene-isocyanuric acid resin was synthesized by reaction of chloromethylated polystryene with isocyanuric acid.The sorption isotherms of phenol from aqueous solution and cyclohexane solution onto the resin were measured.It is of interest to notice that the resin sorbed phenol efficiently though its specific surface area was 0 and did not swell in water,and the sorption capactity from aqueous solution was close to that of phenol onto XAD-4 at the same equilibrium concentration.Sorption enthalpies calculated from the isotherms according to the Clausius-Clapeyron equation were -21-25kJ/mol and -39-41kJ/mol respectively.These values impled that the sorption processes were based on hydrogen bonding.In addition.the details of the hydrogen bonding between the active sites of the resin and phenol were suggested.

  6. Lead sorption-desorption from organic residues.

    Science.gov (United States)

    Duarte Zaragoza, Victor M; Carrillo, Rogelio; Gutierrez Castorena, Carmen M

    2011-01-01

    Sorption and desorption are mechanisms involved in the reduction of metal mobility and bioavailability in organic materials. Metal release from substrates is controlled by desorption. The capacity of coffee husk and pulp residues, vermicompost and cow manure to adsorb Pb2+ was evaluated. The mechanisms involved in the sorption process were also studied. Organic materials retained high concentrations of lead (up to 36,000 mg L(-1)); however, the mechanisms of sorption varied according to the characteristics of each material: degree of decomposition, pH, cation exchange capacity and percentage of organic matter. Vermicompost and manure removed 98% of the Pb from solution. Lead precipitated in manure and vermicompost, forming lead oxide (PbO) and lead ferrite (PbFe4O7). Adsorption isotherms did not fit to the typical Freundlich and Langmuir equations. Not only specific and non-specific adsorption was observed, but also precipitation and coprecipitation. Lead desorption from vermicompost and cow manure was less than 2%. For remediation of Pb-polluted sites, the application of vermicompost and manure is recommended in places with alkaline soils because Pb precipitation can be induced, whereas coffee pulp residue is recommended for acidic soils where Pb is adsorbed.

  7. CO2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk; Hauβ, Thomas; Schaef, Herbert T.; Qafoku, Odeta; Rosso, Kevin M.; Felmy, Andrew R.; Krukowski, Elizabeth G.; Stack, Andrew G.; Grimm, Nico; Bodnar, Robert J.

    2013-01-02

    Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable to CO2. Swelling clays, which are important components of caprocks, may interact with CO2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay-CO2 phase. Finally, at the excess sorption maximum, increasing CO2 sorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak temperature dependence.

  8. Phosphorus isothermal adsorption characteristics of mulch of bioretention

    OpenAIRE

    Mei Ying; Yang Xiao-Hua; Jiang Rong; Di Chong-Li; Zhang Xue-Jun

    2012-01-01

    This study aims to identify mulch of bioretention which has high phosphorus sorption capacity. The phosphorus adsorption characteristics of five types of mulch of bioretention are studied by three isothermal adsorption experiments. Results show that the Langmuir eqution is suitable for describing absorption characteristics of five types of mulch. The positive values of Gibbs free energy for phosphorus indicate that the phosphorus biosorption by five mulches is a non-spontaneous process,...

  9. Porosity and Surface Properites of SBA-15 with Grafted PNIPAAM: A Water Sorption Calorimetry Study

    Science.gov (United States)

    2011-01-01

    Mesoporous silica SBA-15 was modified in a three-step process to obtain a material with poly-N-isopropylacrylamide (PNIPAAM) grafted onto the inner pore surface. Water sorption calorimetry was implemented to characterize the materials obtained after each step regarding the porosity and surface properties. The modification process was carried out by (i) increasing the number of surface silanol groups, (ii) grafting 1-(trichlorosilyl)-2-(m-/p-(chloromethylphenyl) ethane, acting as an anchor for (iii) the polymerization of N-isopropylacrylamide. Water sorption isotherms and the enthalpy of hydration are presented. Pore size distributions were calculated on the basis of the water sorption isotherms by applying the BJH model. Complementary measurements with nitrogen sorption and small-angle X-ray diffraction are presented. The increase in the number of surface silanol groups occurs mainly in the intrawall pores, the anchor is mainly located in the intrawall pores, and the intrawall pore volume is absent after the surface grafting of PNIPAAM. Hence, PNIPAAM seals off the intrawall pores. Water sorption isotherms directly detect the presence of intrawall porosity. Pore size distributions can be calculated from the isotherms. Furthermore, the technique provides information regarding the hydration capability (i.e., wettability of different chemical surfaces) and thermodynamic information. PMID:21928772

  10. Carbon dioxide sorption capacities of coal gasification residues.

    Science.gov (United States)

    Kempka, Thomas; Fernández-Steeger, Tomás; Li, Dong-Yong; Schulten, Marc; Schlüter, Ralph; Krooss, Bernhard M

    2011-02-15

    Underground coal gasification is currently being considered as an economically and environmentally sustainable option for development and utilization of coal deposits not mineable by conventional methods. This emerging technology in combination with carbon capture and sorptive CO2 storage on the residual coke as well as free-gas CO2 storage in the cavities generated in the coal seams after gasification could provide a relevant contribution to the development of Clean Coal Technologies. Three hard coals of different rank from German mining districts were gasified in a laboratory-scale reactor (200 g of coal at 800 °C subjected to 10 L/min air for 200 min). High-pressure CO2 excess sorption isotherms determined before and after gasification revealed an increase of sorption capacity by up to 42%. Thus, physical sorption represents a feasible option for CO2 storage in underground gasification cavities.

  11. Sorption properties of greenwaste biochar for two triazine pesticides.

    Science.gov (United States)

    Zheng, Wei; Guo, Mingxin; Chow, Teresa; Bennett, Douglas N; Rajagopalan, Nandakishore

    2010-09-15

    Biochar is a carbon-rich product generated from biomass through pyrolysis. This study evaluated the ability of an unmodified biochar to sorb two triazine pesticides - atrazine and simazine, and thereby explored potential environmental values of biochar on mitigating pesticide pollution in agricultural production and removing contaminants from wastewater. A greenwaste biochar was produced by heating waste biomass under the oxygen-limited condition at 450 degrees C. The effects of several experimental parameters, including biochar particle size, contact time, solid/solution ratio, and solution pH on the sorption of atrazine and simazine were comprehensively investigated. The biochar with small particle size needed less time to reach sorption equilibrium. The sorption affinity of the biochar for the two pesticides increased with decreasing solid/solution ratio. The sorbed amounts (C(s)) of atrazine and simazine increased from 451 to 1158 mg/kg and 243 to 1066 mg/kg, respectively, when the solid/solution ratio decreased from 1:50 to 1:1000 (g/mL). The sorption of the biochar for both pesticides was favored by low pH. The sorption isotherms of atrazine and simazine on the biochar are nonlinear and follow a Freundlich model. When atrazine and simazine co-existed, a competitive sorption occurred between these two pesticides on the biochar, reflecting a decrease in sorption capacity (K(f)) from 435 to 286 for atrazine and from 514 to 212 for simazine. Combined adsorption and partition mechanisms well depicted sorption of atrazine and simazine on carbonized and noncarbonized fractions of the biochar in the single-solute and co-solute systems.

  12. Moisture buffer capacity of different insulation materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2004-01-01

    lead to more durable constructions. In this paper, a large range of very different thermal insulation materials have been tested in specially constructed laboratory facilities to determine their moisture buffer capacity. Both isothermal and nonisothermal experimental set-ups have been used...

  13. Equilibrium moisture content of waste mixtures from post-consumer carton packaging.

    Science.gov (United States)

    Bacelos, M S; Freire, J T

    2012-01-01

    The manufacturing of boards and roof tiles is one of the routes to reuse waste from the recycled-carton-packaging process. Such a process requires knowledge of the hygroscopic behaviour of these carton-packaging waste mixtures in order to guarantee the quality of the final product (e.g. boards and roof tiles). Thus, with four carton-packaging waste mixtures of selected compositions (A, B, C and D), the sorption isotherms were obtained at air temperature of 20, 40 and 60 degrees C by using the static method. This permits one to investigate which model can relate the equilibrium moisture content of the mixture with that of a pure component through the mass fraction of each component in the mixtures. The results show that the experimental data can be well described by the weighted harmonic mean model. This suggests that the mean equilibrium moisture content of the carton-packaging mixture presents a non-linear relationship with each single, pure compound.

  14. Bio-sorption of neptunium(V) by Pseudomonas fluorescens

    Energy Technology Data Exchange (ETDEWEB)

    Songkasiri, W. [Dept. of Civil Engineering, Northwestern Univ., Evanston, IL (United States); Chemical Technology Div., Argonne National Lab., Argonne, IL (United States); Reed, D.T. [Chemical Technology Div., Argonne National Lab., Argonne, IL (United States); Rittmann, B.E. [Dept. of Civil Engineering, Northwestern Univ., Evanston, IL (United States)

    2002-07-01

    The bio-sorption of neptunyl (NpO{sub 2}{sup +}) by Pseudomonas fluorescens was investigated. The overall goals of this research are to identify key interactions between neptunium and soil bacteria and to model these effects under subsurface-related conditions. Neptunyl, which is generally thought to be non-sorptive, was significantly sorbed under all conditions studied. At initial neptunyl concentrations of 4.75 {mu}M and pH = 7, as much as 85% of the neptunium was sorbed under aerobic conditions. Kinetic studies show that neptunyl was sorbed rapidly within the first 15 minutes. The extent of sorption also increased with pH. In all cases, the sorbed neptunium was shown to be NpO{sub 2}{sup +} by X-ray absorption near edged spectroscopy (XANES) analysis, confirming that there was no reduction to Np(IV) under the conditions of our experiment. The sorption data were modeled using Langmuir and Freundlich isotherms. A comparison of the two approaches showed a significantly better fit for the Freundlich isotherm, and the Freundlich parameter values suggest interactions between sorbed NpO{sub 2}{sup +} molecules. These data show that bio-sorption, even for neptunyl, has a significant role in defining the speciation of neptunium and, hence, its overall mobility in the subsurface. (orig.)

  15. Isothermal Containment Module

    Science.gov (United States)

    1999-01-01

    Isothermal Containment Modules are the temperature-controlling carrier that BioServe built to carry Commercial Generic Bioprocessing Apparatus (CGBA) and in the future, Space Automated Bioproduct Lab (SABL) to the International Space Station.

  16. Non-Isothermal Kinetics.

    Science.gov (United States)

    Brown, M. E.; Phillpotts, C. A. R.

    1978-01-01

    Discusses the principle of nonisothermal kinetics and some of the factors involved in such reactions, especially when considering the reliability of the kinetic parameters, compared to those of isothermal conditions. (GA)

  17. Kinetics, equilibrium and thermodynamics of the sorption of tetrabromobisphenol A on multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Fasfous, Ismail I., E-mail: ismailf@hu.edu.jo [Department of Chemistry, College of Science, Hashemite University, Zarka, Jordan, P.O. Box 330001, Zarka 13133 (Jordan); Radwan, Enas S.; Dawoud, Jamal N. [Department of Chemistry, College of Science, Hashemite University, Zarka, Jordan, P.O. Box 330001, Zarka 13133 (Jordan)

    2010-09-15

    Tetrabromobisphenol A (TBBPA) is widely used as a flame retardant and is relatively persistent in the environment. This study reports the sorption kinetics, equilibrium and thermodynamics of TBBPA on multiwalled carbon nanotubes (MWCNTs). The equilibrium sorption capacity has been significantly improved by increasing the initial TBBPA concentration and contact time. In alkaline conditions and at high temperatures, a large reduction of TBBPA uptake was observed. The equilibrium between TBBPA and MWCNTs was achieved in approximately 60 min with removal of 96% of the TBBPA. The sorption kinetics were well described by a pseudo-second-order rate model, while both Langmuir and Freundlich models described the sorption isotherms well at different temperatures. Thermodynamic parameters suggested that the sorption of TBBPA is exothermic and spontaneous at the temperatures studied.

  18. Heavy metal sorption by marine algae and algal by-products

    Energy Technology Data Exchange (ETDEWEB)

    Sandau, E. [IGV - Inst. fuer Getreideverarbeitung GmbH, Bergholz-Rehbruecke (Germany); Sandau, P. [IGV - Inst. fuer Getreideverarbeitung GmbH, Bergholz-Rehbruecke (Germany); Pulz, O. [IGV - Inst. fuer Getreideverarbeitung GmbH, Bergholz-Rehbruecke (Germany); Zimmermann, M. [Technische Hochschule Berlin (Germany). Fachbereich Chemie und Biotechnik

    1996-12-31

    All the oceans are plentiful with marine algae. Non-viable marine macroalgae are able to adsorb heavy metal ions. Compared with other biosorbents, such as fungi, bacteria, yeasts and microalgae, they have the advantage of being easily available, cheap and having high heavy metal sorption capacities. The by-products of marine phaeophyceae are even more cost-effective heavy metal biosorbers. Experiments of heavy metal sorption using non-viable Fucus vesiculosus, Ascophyllum nodosum and algal by-products were carried out to investigate the factors influencing and optimizing the heavy metal biosorption. The pH value, biomass concentration, heavy metal concentration, heavy metal species, competing ions, algal varieties and time were the most decisive parameters. The sorption isotherms showed increasing sorption capacities and decreasing sorption efficiencies with an increase in the initial heavy metal concentration. Sorption kinetics of different metals were established. Biomass concentration influenced the sorption efficiencies very much, but reduced the sorption capacity per g biomass. The pH value controlled the sorption (pH 3-7) and desorption (pH 1-2) decisively. Beside heavy metal contaminated model waters, actual industrial effluents were treated successfully by algal sorbents in batch experiments and continuous column tests. Transmission electron micrographs of different contaminated and untreated algal specimens are available. (orig.)

  19. SORPTION AND DESORPTION CHARACTERISTICS OF CADMIUM BY FOUR DIFFERENT SOILS IN NORTHEAST CHINA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; SONG Feng-bin

    2005-01-01

    Four soils, phaeozem (PM), saline-alkali soil (SA), meadow albic bleached soil (MA) and dark brown forest soil (DB) from Northeast China were used to examine the sorption and desorption characteristics of Cd and pH influence on it. According to sorption experiment without pH control, the order of amount of absorbed Cd by soils was:SA>PM>DB>MA. The results from non-linear fitting method showed that Langmuir and Freundrich models were more adaptable than Temkin model in describing the sorption data. The maximum sorption amounts from Langmuir model were: PM>SA>MA>DB. Exponential equation for PM and SA and quadratic equation for MA and DB were suitable to fit the desorption data. The order of average desorption percentage was: MA>DB>PM>SA. The amounts of sorption by PM, DB and MA reached the maximum in pH 9.0, while sorption by SA was linearly increased in the experimental range of pH 3.3-11.4. In uniform pH, however, Cd sorption by SA was the minimum among four soils, which indicated that the more amounts of Cd absorbed by SA in isotherm sorption were ascribed to the higher soil pH. The higher sorption of Cd in PM resulted from the higher percentage of organic matter and clay components.

  20. Recommended coefficients for sorption of iodine, silver, and cesium on graphite dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Stempniewicz, Marek M., E-mail: stempniewicz@nrg.eu [NRG Arnhem, Utrechtseweg 310, PO Box 9034, 6800 ES Arnhem (Netherlands); Goede, Pieter, E-mail: goedep@gmail.com [PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa)

    2016-09-15

    Highlights: • Sorption of fission product vapors on dust particles—important safety aspect of HTRs. • Sorption coefficients represent well the AVR data for cesium, iodine, and silver on dust. • Sorption rates higher at low temperatures and lower at high temperatures. • A set of recommended sorption coefficient for computer code users. - Abstract: This paper describes the work performed to find the sorption coefficients that represent well the available experimental data for cesium, iodine, and silver on dust particles. The purpose of this work is to generate a set of coefficients that may be recommended for computer code users. The following data was correlated: • I-131 on AVR dust. • Ag-110m on AVR dust. • Cs-134 and Cs-137 on AVR dust. The results are summarized as follows: • The available data can be correlated. The data scatter is about 4 orders of magnitude. Therefore the coefficients of the Langmuir isotherms vary by 4 orders of magnitude. • Sorption rates are higher at low temperatures and lower at high temperatures. This tendency has been observed in the data compiled at Oak Ridge. It is therefore surmised that the highest value of the sorption coefficients are appropriate for the low temperatures and the lowest value of the sorption coefficients are appropriate for the high temperatures. The recommended sorption coefficients are presented in this paper. • The present set of coefficients is very rough and should be a subject for future verification against experimental data.

  1. Comparative sorption and desorption behaviors of PFHxS and PFOS on sequentially extracted humic substances

    Institute of Scientific and Technical Information of China (English)

    Lixia Zhao; Yifeng Zhang; Shuhong Fang; Lingyan Zhu; Zhengtao Liu

    2014-01-01

    The sorption and desorption behaviors of two perfluoroalkane sulfonates (PFSAs),including perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS) on two humic acids (HAs) and humin (HM),which were extracted from a peat soil,were investigated.The sorption kinetics and isotherms showed that the sorption of PFOS on the humic substances (HSs) was much higher than PFHxS.For the same PFSA compound,the sorption on HSs followed the order of HM > HA2 > HA1.These suggest that hydrophobic interaction plays a key role in the sorption of PFSAs on HSs.The sorption capacities of PFSAs on HSs were significantly related to their aliphaticity,but negatively correlated to aromatic carbons,indicating the importance of aliphatic groups in the sorption of PFSAs.Compared to PFOS,PFHxS displayed distinct desorption hysteresis,probably due to irreversible pore deformation after sorption of PFHxS.The sorption of the two PFSAs on HSs decreased with an increase in pH in the solution.This is ascribed to the electrostatic interaction and hydrogen bonding at lower pH.Hydrophobic interaction might also be stronger at lower pH due to the aggregation of HSs.

  2. Sorption and transformation of the reactive tracers resazurin and resorufin in natural river sediments

    Directory of Open Access Journals (Sweden)

    D. Lemke

    2013-10-01

    Full Text Available Resazurin (Raz and its reaction product resorufin (Rru have increasingly been used as reactive tracers to quantify metabolic activity and hyporheic exchange in streams. Previous works have indicated that these compounds undergo sorption in stream sediments. We present a series of laboratory column and batch experiments on Raz and Rru transport, sorption, and transformation within sediments with different physicochemical properties under neutral and alkaline conditions. The data of the column experiments were fitted by a model accounting for physical transport, equilibrium and kinetic sorption, and three first-order reactions. The most likely parameters and their uncertainty were determined by a Markov-Chain Monte Carlo approach. Linear and non-linear sorption isotherms of both compounds were obtained by batch experiments. We found that kinetic sorption dominates sorption of both Raz and Rru, with characteristic timescales of sorption in the order of > 80 min. The linear sorption models for both Raz and Rru appeared adequate for concentrations that are typically applied in field-tracer tests. The supposed two-site sorption model helps interpreting transient tracer tests using the Raz–Rru system.

  3. Effect of biosurfactant[0] on the sorption of phenanthrene onto original and H2O2-treated soils

    Institute of Scientific and Technical Information of China (English)

    PEI Xiaohong; ZHAN Xinhua; ZHOU Lixiang

    2009-01-01

    The objective of this study was to examine the effect of biosurfactant on sorption of phenanthrene (PHE) onto the original or H2O2-treated black loamy soil (typic isohumisols) and red sandy soil (typic ferralisols). The sorption isotherms were performed with the original and "soft" carbon-removed soils in the presence and absence of biosurfactant (200 mg/L). The sorption and degradation of biosurfactant were investigated. The result showed that organic matter played an important role in PHE sorption onto the black loamy and red sandy soils, and the PHE sorption isotherms on the "soft" carbon-removed soils exhibited more nonlinearity than those on the original soils. The values of partition coefficient (Kd) on the original black loamy soil with or without 200 mg/L biosurfactant were 181.6 and 494.5 mL/g, respectively. Correspondingly, in the red sandy soil, Kd was 246.4 and 212.8 mL/g in the presence or absence of biosurfactant, respectively. The changes of Kd suggested that biosurfactant inhibited PHE sorption onto the black loamy soil, but facilitated PHE sorption onto the red sandy soil. The nonlinearity of PHE sorption isotherm was decreased in the presence of biosurfactant. Site specific sorption might occur during PHE sorption onto both the original and the "soft" carbon-removed soils in the presence of biosurfactant. It was noted that biosurfactant could also be sorbed onto soils. The maximal sorption capacity of the red sandy soil for biosurfactant was (76.9 ± 0.007) μg/g, which was 1.31 times that of black loamy soil. Biosurfactant was degraded quickly in the two selected soils, and 92% of biosurfactant were mineralized throughout the incubation experiment for 7 d. It implied that biosurfactant should be added frequently when the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils was conducted through PAH desorption approach facilitated by biosurfactant.

  4. Measured moisture properties for alternative insulation products

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Padfield, Tim

    1999-01-01

    During the past few years there has been a growing interest in using alternative insulation products in buildings. Among these products are the organic materials cellulose fibre, flax and sheep's wool as well as the inorganic perlite. The organic materials are regarded with some suspicion, because...... of their hygroscopicity. This paper describes two of the moisture-related properties of these materials: the water sorption and the water vapour transmission. For reference, some mineral fibre products are studied as well....

  5. Measured moisture properties for alternative insulation products

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Padfield, Tim

    1999-01-01

    During the past few years there has been a growing interest in using alternative insulation products in buildings. Among these products are the organic materials cellulose fibre, flax and sheep's wool as well as the inorganic perlite. The organic materials are regarded with some suspicion, because...... of their hygroscopicity. This paper describes two of the moisture-related properties of these materials: the water sorption and the water vapour transmission. For reference, some mineral fibre products are studied as well....

  6. Thermodynamics of imidacloprid sorption in Croatian soils

    Science.gov (United States)

    Milin, Čedomila; Broznic, Dalibor

    2015-04-01

    Neonicotinoids are increasingly replacing the organophosphate and methylcarbamate acetylcholinesterase inhibitors which are losing their effectiveness because of selection for resistant pest populations. Imidacloprid is the most important neonicotinoid with low soil persistence, high insecticidal potency and relatively low mammalian toxicity. In Croatia, imidacloprid is most commonly used in olive growing areas, including Istria and Kvarner islands, as an effective means of olive fruit fly infestation control. Sorption-desorption behavior of imidacloprid in six soils collected from five coastal regions in Croatia at 20, 30 and 40°C was investigated using batch equilibrium technique. Isothermal data were applied to Freundlich, Langmuir and Temkin equation, and the thermodynamic parameters ΔH°, ΔG°, ΔS° were calculated. The sorption isotherm curves were of non-linear and may be classified as L-type suggesting a relatively high sorption capacity for imidacloprid. Our results showed that the KFsor values decreased for all the tested soils as the temperature increases, indicating that the temperature strongly influence the sorption. Values of ΔG° were negative (-4.65 to -2.00 kJ/mol) indicating that at all experimental temperatures the interactions of imidacloprid with soils were spontaneous process. The negative and small ΔH° values (-19.79 to -8.89 kJ/mol) were in the range of weak forces, such as H-bonds, consistent with interactions and par¬titioning of the imidacloprid molecules into soil organic matter. The ΔS° values followed the range of -57.12 to -14.51 J/molK, suggesting that imidacloprid molecules lose entropy during transition from the solution phase to soil surface. It was found that imidacloprid desorption from soil was concentration and temperature dependent, i.e. at lower imidacloprid concentrations and temperature, lower desorption percentage occurred. Desorption studies revealed that hysteretic behavior under different temperature

  7. Capacity and mechanisms of ammonium and cadmium sorption on different wetland-plant derived biochars

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xiaoqiang [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); Hao, Hulin [Ningbo Raw Water Resource Research Academy, Ningbo (China); Zhang, Changkuan [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China); He, Zhenli [Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL 34945 (United States); Yang, Xiaoe, E-mail: xyang571@yahoo.com [Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058 (China)

    2016-01-01

    The objective of this study was to investigate the relationship between Cd{sup 2+}/NH{sub 4}{sup +} sorption and physicochemical properties of biochars produced from different wetland plants. Biochars from six species of wetland plants (i.e., Canna indica, Pennisetum purpureum Schum, Thalia dealbata, Zizania caduciflora, Phragmites australis and Vetiveria zizanioides) were obtained at 500 °C and characterized, and their sorption for ammonium and cadmium was determined. There were significant differences in elemental composition, functional groups and specific surface area among the biochars derived from different wetland plant species. Sorption of ammonium and cadmium on the biochars could be described by a pseudo second order kinetic model, and the simple Langmuir model fits the isotherm data better than the Freundlich or Temkin model. The C. indica derived biochar had the largest sorption capacity for NH{sub 4}{sup +} and Cd{sup 2+}, with a maximum sorption of 13.35 and 125.8 mg g{sup −1}, respectively. P. purpureum Schum derived biochar had a similar maximum sorption (119.3 mg g{sup −1}) for Cd{sup 2+}. Ammonium sorption was mainly controlled by cation exchange, surface complexation with oxygen-containing functional groups and the formation of magnesium ammonium phosphate compounds, whereas for Cd{sup 2+} sorption, the formation of cadmium phosphate precipitates, cation exchange and binding to oxygen-containing groups were the major possible mechanisms. In addition, the sorption of ammonium and cadmium was not affected by surface area and microporosity of the biochars. - Highlights: • Biochars varied in physicochemical properties and adsorption capacity. • Canna indica derived biochar has a high sorption capacity for Cd{sup 2+}. • NH{sub 4}{sup +} and Cd{sup 2+} sorption on biochars fits a pseudo second order and Langmuir model. • Sorption mechanism is related to complexation, cation exchange and precipitation.

  8. Sorption of Emerging Organic Wastewater Contaminants to Four Soils

    Directory of Open Access Journals (Sweden)

    Sarah Roberts

    2014-04-01

    Full Text Available Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs, chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal care and cleaning products, have been observed in septic tank effluent and the environment. Sorption of OWC mass to soil is a key mechanism in the removal and retardation of many of these chemicals in effluent as it travels through an STU. The primary purpose of this study was to investigate the relationship between the fraction of organic carbon of soil and the equilibrium sorption partitioning coefficient of a selected group of relevant and diverse OWCs. A secondary goal is to evaluate current methods of modeling the sorption of selected OWCs in soil. Five point Freundlich isotherms were constructed from equilibrium sorption batch tests for target OWCs with four different soils. For soils with organic carbon fraction between 0.021 and 0.054, Kd values were calculated between 60 and 185 for 4-nonylphenol, 75 to 260 for triclosan, 115 to 270 for bisphenol-A, 3 to 255 for 17β-estradiol, 40 to 55 for 17α-ethynylestradiol, and 28 to 70 for estrone. An empirically derived, direct relationship between foc and Kd may be a useful approach to estimating sorption for a soil based on organic carbon content.

  9. A study of dyes sorption on biobased cryogels

    Energy Technology Data Exchange (ETDEWEB)

    Dobritoiu, Rodica; Patachia, Silvia, E-mail: st.patachia@unitbv.ro

    2013-11-15

    Three types of biopolymers based materials were synthesized and tested as adsorbents for the dyes from aqueous solutions. Blends based on poly (vinyl alcohol) [PVA] and scleroglucan [Scl], cellulose micro-fibres [cel] and zein, respectively, have been prepared by repeated freezing–thawing cycles. Methylene blue [MB] was selected as a model dye in order to evaluate the capacity of the prepared materials to remove the dyes from aqueous solutions. The effects of the initial dye concentration, contact time and the composition of materials on the kinetic and thermodynamic parameters of sorption were discussed. The pseudo-second-order kinetics was found to better fit the experimental data thus being able to consistently predict the amount of dye adsorbed over the entire sorption period. The sorption equilibrium data obey Freundlich isotherm. Sorption capacity was evaluated both by dye solution and cryogel analysis by using VIS spectrometry and image analysis with CIELAB system. The sorption of monomer or aggregated dye molecules was identified and correlated with the type and morphology of the gel. The highest efficiency in MB removal was obtained for Scl/PVA cryogels in 1:9 weight ratio (9.5279 mg/g MB for an initial concentration by 8 × 10{sup −5} mol/L in MB). These materials are suitable as sorbents for the advanced removal of dyes from waste water.

  10. Kinetics and thermodynamics of basic dye sorption on phosphoric acid esterifying soybean hull with solid phase preparation technique.

    Science.gov (United States)

    Gong, Renmin; Sun, Jin; Zhang, Demin; Zhong, Keding; Zhu, Guoping

    2008-07-01

    In this paper, the solid phase preparation method of a cationic sorbent, which bears hydroxyl groups of phosphoric acid derived from esterified soybean hull (ESH), was reported. The sorption kinetics and thermodynamics of two basic dyes, acridine orange (AO) and malachite green (MG), from aqueous solution onto ESH were investigated with a batch system. The isothermal data of dye sorptions followed the Langmuir model better than the Freundlich model. The maximum sorption capacity (Q(m)) of ESH for AO and MG was 238.1 mg/g and 178.57 mg/g, respectively. The dye sorption processes could be described by the pseudo-second-order kinetic model. The thermodynamic study indicated that the dye sorptions were spontaneous and exothermic. Lower temperatures were favorable for the sorption processes.

  11. Sorption of malachite green from aqueous solution by potato peel: Kinetics and equilibrium modeling using non-linear analysis method

    Directory of Open Access Journals (Sweden)

    El-Khamsa Guechi

    2016-09-01

    Full Text Available Potato peel (PP was used as a biosorbent to remove malachite green (MG from aqueous solution under various operating conditions. The effect of the experimental parameters such as initial dye concentration, biosorbent dose, initial pH, stirring speed, temperature, ionic strength and biosorbent particle size was investigated through a number of batch sorption experiments. The sorption kinetic uptake for MG by PP at various initial dye concentrations was analyzed by non-linear method using pseudo-first, pseudo-second and pseudo-nth order models. It was found that the pseudo-nth order kinetic model was the best applicable model to describe the sorption kinetic data and the order n of sorption reaction was calculated in the range from 0.71 to 2.71. Three sorption isotherms namely the Langmuir, Freundlich and Redlich–Peterson isotherms in their non-linear forms were applied to the biosorption equilibrium data. Both the Langmuir and Redlich–Peterson models were found to fit the sorption isotherm data well, but the Redlich–Peterson model was better. Thermodynamic parameters show that the sorption process of MG is endothermic and more effective process at high temperatures. The results revealed that PP is very effective for the biosorption of MG from aqueous solutions.

  12. Sorption and desorption studies of a reactive azo dye on effective disposal of redundant material.

    Science.gov (United States)

    Çelekli, Abuzer; Bozkurt, Hüseyin

    2013-07-01

    The effective disposal of redundant elephant dung (ED) is important for environmental protection and utilization of resource. The aim of this study was to remove a toxic-azo dye, Reactive Red (RR) 120, using this relatively cheap material as a new adsorbent. The FTIR-ATR spectra of ED powders before and after the sorption of RR 120 and zero point charge (pHzpc) of ED were determined. The sorption capacity of ED for removing of RR 120 were carried out as functions of particle size, adsorbent dose, pH, temperature, ionic strength, initial dye concentration, and contact time. Sorption isotherm, kinetic, activation energy, thermodynamic, and desorption parameters of RR 120 on ED were studied. The sorption process was found to be dependent on particle size, adsorbent dose, pH, temperature, ionic strength, initial dye concentration, and contact time. FTIR-ATR spectroscopy indicated that amine and amide groups have significant role on the sorption of RR 120 on ED. The pHzpc of ED was found to be 7.3. Sorption kinetic of RR 120 on ED was well described by sigmoidal Logistic model. The Langmuir isotherm was well fitted to the equilibrium data. The maximum sorption capacity was 95.71 mg g(-1). The sorption of RR 120 on ED was mainly physical and exothermic according to results of D-R isotherm, Arrhenius equation, thermodynamic, and desorption studies. The thermodynamic parameters showed that this process was feasible and spontaneous. This study showed that ED as a low-cost adsorbent had a great potential for the removal of RR 120 as an alternative eco-friendly process.

  13. Sorption of tylosin and sulfamethazine on solid humic acid.

    Science.gov (United States)

    Guo, Xuetao; Tu, Bei; Ge, Jianhua; Yang, Chen; Song, Xiaomei; Dang, Zhi

    2016-05-01

    Tylosin (TYL) and sulfamethazine (SMT) are ionizable and polar antimicrobial compounds, which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid (HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions (pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing pH (2.0-7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL(+)/SMT(+) species and the functional groups of HA. Increasing ionic strength resulted in a considerable reduction in the Kd values of TYL and SMT, hinting that interactions between H bonds and π-π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared (FT-IR) and (13)C-nuclear magnetic resonance (NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds, respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions. Copyright © 2015. Published by Elsevier B.V.

  14. Sorption of 1-naphthol by plant cuticular fractions

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment, but sorption mechanism is still not fully understood. In this study,sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction. Toward this end, cuticular materials were isolated from the fruits of tomato by chemical method. The tomato cuticle sheet consisted of waxes(6.5 wt%), cuticular monomer (69.5 wt%), and polysaccharide (24.0 wt%). Isotherms of 1-naphthol to the cuticular fractions were nonlinear (N value (0.82 - 0.90)) at the whole tested concentration ranges. The Koc/Kow ratios for bulk cuticle (TC1), dewaxed cuticle(TC2), cutin (TC4), and desugared cuticle (TC5) were larger than unity, suggested that tomato bulk cuticle and cutin are much powerful sorption medium. Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3). The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions.Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material. There was a linear negative trend between Koc values and the amount of polysaccharides or fraction's polarities((N+O)/C); while a linear positive relationship between Koc values and the content of cutin monomer (linear R2 = 0.993) was observed for present in the cuticular fractions. Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer, contributing to 91.7% of the total sorption of tomato bulk cuticle.

  15. Sorption of Cd{sup 2+} on mercapto and amino functionalized palygorskite

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xuefeng [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Original Environmental Quality of MOA, Agro-Environmental Protection Institute of Ministry of Agriculture, Tianjin 300191 (China); Han, Jun [Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Xu, Yingming, E-mail: dingandliang@gmail.com [Key Laboratory of Original Environmental Quality of MOA, Agro-Environmental Protection Institute of Ministry of Agriculture, Tianjin 300191 (China); Wang, Lin; Sun, Yuebing [Key Laboratory of Original Environmental Quality of MOA, Agro-Environmental Protection Institute of Ministry of Agriculture, Tianjin 300191 (China); Tan, Xin [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2014-12-15

    Graphical abstract: Sorption of Cd{sup 2+} on PAL, PAL-SH and PAL-NH{sub 2} involved different mechanisms. For pristine palygorskite, Cd{sup 2+} reacted with surface hydroxyl groups to form surface complexation; for mercapto functionalized palygorskite, the complexation of Cd{sup 2+} with mercapto groups existed in addition to the complexation with surface hydroxyl groups; for amino functionalized palygorskite, surface precipitation of Cd{sup 2+} with OH- and CO{sub 2} to form CdCO{sub 3} played an important role in the sorption process except complexation with amino and hydroxyl groups. - Highlights: • Surface modification increased the sorption efficiency significantly. • The sorption process was endothermic and driven by entropy changes. • The sorption mechanisms were investigated by XRD, FTIR, {sup 29}Si CP/MAS NMR and XPS. • The sorption mechanisms involved surface complexation and surface precipitation. - Abstract: Mercapto and amino functionalized palygorskite samples were prepared by nanotexturization method, respectively, and applied for the sorption of Cd{sup 2+} from aqueous solution to investigate the sorption mechanism and assess the application potential for the remediation of Cd polluted water and soils. The samples before and after sorption were characterized through XRD, FTIR, {sup 29}Si CP/MAS NMR and XPS. The sorption thermodynamics, kinetics and mechanisms of Cd{sup 2+} sorption on mercapto and amino functionalized palygorskite were studied. Langmuir isotherm was proved to describe the sorption data better and pseudo second order kinetic model could fit the sorption kinetic processes well. Functionalization increased the sorption amounts significantly compared to pristine palygorskite. The positive enthalpy change confirmed that the sorption process was endothermic. The positive entropy changes revealed that sorption of Cd{sup 2+} was driven by entropy changes. Combined the results of analyses of the diffraction peaks by XRD, vibration

  16. Influence of the temperature in the uranium (Vi) sorption in zirconium diphosphate; Influencia de la temperatura en la sorcion de uranio (VI) en difosfato de circonio

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, N.; Solis, D. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon y Paseo Tollocan, 50120 Toluca, Estado de Mexico (Mexico); Ordonez R, E., E-mail: nidgg@yahoo.com.mx [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-10-15

    In the present work was evaluated the uranium (Vi) sorption at 10, 20, 30, 40 and 60 C on the zirconium diphosphate (ZrP{sub 2}O{sub 7}). They were carried out kinetic and isotherms using the method by lots, these will allow to fix the sorption time (kinetic) and to explain the behavior of this sorption in different ph conditions and temperature (isotherm). The quantity of retained uranium in the surface was quantified by means of the fluorescence technique. (Author)

  17. Phosphorus sorption-desorption and effects of temperature, pH and salinity on phosphorus sorption in marsh soils from coastal wetlands with different flooding conditions.

    Science.gov (United States)

    Bai, Junhong; Ye, Xiaofei; Jia, Jia; Zhang, Guangliang; Zhao, Qingqing; Cui, Baoshan; Liu, Xinhui

    2017-12-01

    Wetland soils act as a sink or source of phosphorus (P) to the overlaying water due to phosphorus sorption-desorption processes. Litter information is available on sorption and desorption behaviors of phosphorus in coastal wetlands with different flooding conditions. Laboratory experiments were conducted to investigate phosphorus sorption-desorption processes, fractions of adsorbed phosphorus, and the effects of salinity, pH and temperature on phosphorus sorption on soils in tidal-flooding wetlands (TW), freshwater-flooding wetlands (FW) and seasonal-flooding wetlands (SW) in the Yellow River Delta. Our results showed that the freshly adsorbed phosphorus dominantly exists in Occluded-P and Fe/AlP and their percentages increased with increasing phosphorus adsorbed. Phosphorus sorption isotherms could be better described by the modified Langmuir model than by the modified Freundlich model. A binomial equation could be properly used to describe the effects of salinity, pH, and temperature on phosphorus sorption. Phosphorus sorption generally increased with increasing salinity, pH, and temperature at lower ranges, while decreased in excess of some threshold values. The maximum phosphorus sorption capacity (Qmax) was larger for FW soils (256 mg/kg) compared with TW (218 mg/kg) and SW soils (235 mg/kg) (p < 0.05). The percentage of phosphorus desorption (Pdes) in the FW soils (7.5-63.5%) was much lower than those in TW (27.7-124.9%) and SW soils (19.2-108.5%). The initial soil organic matter, pH and the exchangeable Al, Fe and Cd contents were important factors influencing P sorption and desorption. The findings of this study indicate that freshwater restoration can contribute to controlling the eutrophication status of water bodies through increasing P sorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

    Institute of Scientific and Technical Information of China (English)

    GAO Min-ling; DAI Shu-gui; MA Yong-min; ZHANG Pi

    2007-01-01

    Sorption of chlorotoluron in ammonium sulfate.urea and atrazine multi-solutes system was investigated by batch experiments.The results showed application of nitrogen fertilizers to the soil could affeCt the behavior of chlorotoluron.At the same concentration of N,sorption of chlorotoluron decreased as the concentration of atrazine increased on the day O and 6 in soil.respectively.The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water,ammonium sulfate and urea solution for 6 d.That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments.The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system,but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers.That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.

  19. β-Zeolite modified by ethylenediamine for sorption of Th(IV)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Peng; Wu, Hanyu; Yuan, Ni; Yin, Zhuoxin; Pan, Duoqiang; Wu, Wangsuo [Lanzhou Univ. (China). Radiochemistry Lab.; Ministry of Education, Lanzhou (China). Key Lab. of Special Function Materials and Structure Design

    2017-08-01

    β-Zeolite-EDA was modified with ethylenediamine (EDA) after synthesized. The synthesized material was characterized and used for removal of Th(IV) from aqueous solutions. The influences of pH, ionic strength, contact time, temperature and humic acid (HA) on Th(IV) sorption onto synthesized β-zeolite-EDA was studied by batch technique. The dynamic process showed that the sorption of Th(IV) onto β-zeolite-EDA matched the pseudo-second-order kinetics model. The sorption of Th(IV) on β-zeolite-EDA was significantly dependent on pH values, the sorption percentage increased markedly at pH 3.5-4.5, and then maintained a steady state as pH values increased. Through simulating the sorption isotherms by Langmuir, Freundlich and Dubini-Radushkevich (D-R) models, it could be seen respectively that the sorption pattern of Th(IV) on β-zeolite-EDA was mainly controlled by surface complexation, and that the sorption processes was endothermic and spontaneous. The presence of HA increased Th(IV) sorption on β-zeolite-EDA.

  20. Sorption of benzothiazoles onto sandy aquifer material under equilibrium and nonequlibrium conditions

    Directory of Open Access Journals (Sweden)

    Kragulj Marijana M.

    2014-01-01

    Full Text Available In this study, the sorption behaviour of 1,3-benzothiazole (BT and 2-(methylthiobenzothiazole (MTBT was investigated on Danube geosorbent under equilibrium and nonequilibrium conditions. All sorption isotherms fitted well with the Freundlich model (R2=0.932-0.993. The results showed that organic matter of the Danube geosorbent has a higher sorption affinity for the more hydrophobic MTBT compared to BT. However, sorption-desorption experiments showed that MTBT was more easily desorbed than BT molecules, which indicates the importance of absorption relative to adsorption in the overall sorption mechanism of MTBT. In general, molecules of BT and MTBT were more easily desorbed in the lower concentration range, which resulted in an increase in the hysteresis indices with increasing concentrations. Column experiments revealed that retention of the investigated compounds on the aquifer material followed the compound’s hydrophobicity. BT showed a lower retention, in accordance with its lower sorption affinity obtained in the static experiments, while MTBT showed a greater sorption affinity, and thus had a longer retention time on the column. Thus during transport BT represent greater risk for groundwaters than MTBT. These results have increased our understanding of benzothiazoles sorption and desorption process which represent one of the most important factors which influence the behaviour of organic compounds in the environment.

  1. Energy Aspects of CO2 Sorption in the Context of Sequestration in Coal Deposits

    Institute of Scientific and Technical Information of China (English)

    PawełBaran; Katarzyna Zarębska; Adam Nodzeński

    2014-01-01

    This paper summarises the results of experimental testing of carbon dioxide sorption on five coal samples. Sorption tests were done at the temperature 288, 298, 313 and 323 K, in the pressure range 0-5 MPa. The analysis of sorption isotherms and the effects of temperature on sorp-tion capacity reveal that in the case of samples NR1, Pn, Tu, Be the temperature increase from 298 to 323 K led to 1.3-fold decrease of the sorption value. In the case of coal Th the decrease of sorption capacity was 3-fold. It appears that the analysis of maceral content plays a major role. In the case of coals, porosity is associated with the petrographic composition. The values of the isosteric heat of sorption and the work of expansion and desorption were derived for the investigated sorption sys-tems. Test data reveal that for hard coals the isosteric heat is inversely proportional to the“reserve”of volumetric work-a major parameter triggering the sudden release of gas from the coalbed, thus enabling us to assess the potential risk involved in rapid unsealing of the coalbed.

  2. Sorption and desorption of pentachlorophenol to black carbon of three different origins.

    Science.gov (United States)

    Luo, Ling; Lou, Liping; Cui, Xinyi; Wu, Binbin; Hou, Jiaai; Xun, Bei; Xu, Xinhua; Chen, Yingxu

    2011-01-30

    Rice straw charcoal, soot and fly ash (collectively termed "black carbon" or BC), which were found to widely exist in the environment and exhibit strong sorption of many organic compounds, were prepared for this study, and recorded as RC, SC, and FC, respectively. The characterization, sorption isotherm, and the effect of pH (from 3.0 to 9.0) on sorption capacity of each BC were investigated. It is demonstrated that RC possessed the largest surface area (234.9 m(2)/g), the highest porosity (0.4392 mL/g), and the largest amount of functional groups (2.995 mmol/g) of all. All the Freundlich, Langmuir and Dual-mode model can fit the sorption data of each BC well. The pH value could apparently affect the sorption capacity of pentachlorophenol (PCP) to BCs, which reached maximum value at pH 4.0. Furthermore, in order to validate the effect of pH on desorption capacity, we designed sorption-desorption cycle experiments at pH 9.0 and then pH 7.0, and found that the effect of pH on irreversible sorption and hysteresis effects were significant. As pH value decreasing from 9.0 to 7.0, the irreversible sorption capacities for RC, FC, and SC increased, and the desorption hysteresis index (H) values of PCP increased approximately 3 times for each BC.

  3. An insight into the removal of fluoroquinolones in activated sludge process: Sorption and biodegradation characteristics.

    Science.gov (United States)

    Wang, Lu; Qiang, Zhimin; Li, Yangang; Ben, Weiwei

    2017-06-01

    The detailed sorption steps and biodegradation characteristics of fluoroquinolones (FQs) including ciprofloxacin, enrofloxacin, lomefloxacin, norfloxacin, and ofloxacin were investigated through batch experiments. The results indicate that FQs at a total concentration of 500μg/L caused little inhibition of sludge bioactivity. Sorption was the primary removal pathway of FQs in the activated sludge process, followed by biodegradation, while hydrolysis and volatilization were negligible. FQ sorption on activated sludge was a reversible process governed by surface reaction. Henry and Freundlich models could describe the FQ sorption isotherms well in the concentration range of 100-300μg/L. Thermodynamic parameters revealed that FQ sorption on activated sludge is spontaneous, exothermic, and enthalpy-driven. Hydrophobicity-independent mechanisms determined the FQ sorption affinity with activated sludge. The zwitterion of FQs had the strongest sorption affinity, followed by cation and anion, and aerobic condition facilitated FQ sorption. FQs were slowly biodegradable, with long half-lives (>100hr). FQ biodegradation was enhanced with increasing temperature and under aerobic condition, and thus was possibly achieved through co-metabolism during nitrification. This study provides an insight into the removal kinetics and mechanism of FQs in the activated sludge process, but also helps assess the environmental risks of FQs resulting from sludge disposal. Copyright © 2016. Published by Elsevier B.V.

  4. Effects of dissolved organic matter from sewage sludge on sorption of tetrabromobisphenol A by soils

    Institute of Scientific and Technical Information of China (English)

    SUN Zhaohai; MAO Li; XIAN Qiming; YU Yijun; LI Hui; YU Hongxia

    2008-01-01

    Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics of soils and the concentrations of DOM present. TBBPA sorption by Henan (HN) soil (sandy loam) and Liaoning (LN) soil (loamy clay) was promoted in the presence of DOM at low concentration (≤ 90 mg organic carbon (OC)/L), and the sorption was promoted by HN soil and inhibited by LN soil at DOM added concentration of 180 mg OC/L. TBBPA sorption by Guangxi (GX) soil (silt loam) was always inhibited in the presence of DOM. It was also found that the amount of TBBPA sorbed decreased with the increase in the solution pH value in the absence of DOM. The influencing mechanisms of DOM on the sorption of TBBPA by soils were also discussed.

  5. Chain Length Effects of Linear Alkanes in Zeolite Ferrierite. 1. Sorption and 13C NMR Experiments

    NARCIS (Netherlands)

    Well, van Willy J.M.; Cottin, Xavier; Haan, vde Jan W.; Smit, Berend; Nivarthy, Gautam; Lercher, Johannes A.; Hooff, van Jan H.C.; Santen, van Rutger A.

    1998-01-01

    Temperature-programmed desorption, heat of adsorption, adsorption isotherm, and 13C NMR measurements are used to study the sorption properties of linear alkanes in ferrierite. Some remarkable chain length effects are found in these properties. While propane, n-butane, and n-pentane fill the ferrieri

  6. chain length effects of linear alkanes in zeolite ferrierite.1. sorption and 13C NMR experiments

    NARCIS (Netherlands)

    van Well, Willy J.M.; Cottin, Xavier; vde Haan, Jan W.; Smit, Berend; Nivarthy, G.S.; Lercher, J.A.; van Hooff, Jan H.C.; van Santen, Rutger A.

    1998-01-01

    Temperature-programmed desorption, heat of adsorption, adsorption isotherm, and 13C NMR measurements are used to study the sorption properties of linear alkanes in ferrierite. Some remarkable chain length effects are found in these properties. While propane, n-butane, and n-pentane fill the

  7. Evaluation of Water Vapor Sorption Hysteresis in Soils: The Role of Organic Matter and Clay

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    hysteresis and hysteresis was dependent on the degree of interlayer expansion, where kaolinite exhibited little hysteresis and montmorillonite showed significant hysteresis between the sorption isotherms. For soils, clay and OM effects on hysteresis depended on the method used for quantifying hysteresis...

  8. Sorption Removal of Pb(Ⅱ) from Solution by Uncalcined and Calcined MgAl-Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    ZHANG, Shu-Qin; HOU, Wan-Guo

    2007-01-01

    Layered double hydroxide (LDH) with a Mg/Al molar ratio of 1∶1 was synthesized by using a co-precipitation method and its calcined product (CLDH) was obtained by calcination of the MgAl-LDH at 500 ℃. The sorption removal of Pb2+ from solution was investigated, finding that both LDH and CLDH show good sorption ability and they could be used as a new type of environmental sorbent for the removal of Pb2+ from water. The sorption kinetics and the sorption isotherms of Pb2+ on both LDH and CLDH can be described by the pseudo-second order kinetics and Freundlich isotherm, respectively, under the studied conditions. The sorption amounts of Pb2+ on LDH and CLDH are independent of pH in a pH range of about 3-10. The presence of NaNO3 may inhibit the sorption of Pb2+ on LDH while hardly affect that on CLDH. The sorption mechanism of Pb2+ on LDH and CLDH may be attributed to the surface precipitation and the surface complex adsorption. The surface complex adsorption may be further distinguished to the chemical binding adsorption forming the inner-sphere surface complexes and the electrostatic binding adsorption forming the outer-sphere surface complexes. The sorption mechanism of Pb2+ on LDH may be attributed to the surface precipitation and the electrostatic binding adsorption, while that on CLDH may be attributed to the surface precipitation and the chemical binding adsorption.

  9. Competitive sorption between 17α-ethinyl estradiol and bisphenol A/4-n-nonylphenol by soils

    Institute of Scientific and Technical Information of China (English)

    Jianzhong Li; Lu Jiang; Xi Xiang; Shuang Xu; Rou Wen; Xiang Liu

    2013-01-01

    The sorption of 17αt-ethinyl estradiol (EE2),bisphenol A (BPA),and 4-n-nonylphenol (NP) in single systems and the sorption of EE2 with different initial aqueous concentrations of BPA or NP were examined using three soils.Results showed that all sorption isotherms were nonlinear and fit the Freundlich model.The degree of nonlinearity was in the order BPA (0.537-0.686) > EE2 (0.705-0.858) >NP (0.875-0.0.951) in single systems.The isotherm linearity index of EE2 sorption calculated by the Freundlich model for Loam,Silt Loam and Silt increased from 0.758,0.705 and 0.858,to 0.889,0.910 and 0.969,respectively,when BPA concentration increased from 0 to 1000 μg/L,but the effect of NP was comparably minimal.Additionally,EE2 significantly suppressed the sorption of BPA,but insignificantly suppressed that of NP.These findings can be attributed to the difference of sorption affinity of EE2,NP and BPA on the hard carbon (e.g.,black carbon) of soil organic matter that dominated the sorption in the low equilibrium aqueous concentration range of endocrine-disrupting chemicals (EDCs).Competitive sorption among EDCs presents new challenges for predicting the transport and fate of EDCs under the influence of co-solutes.

  10. Oil spill sorption using raw and acetylated sugarcane bagasse

    Institute of Scientific and Technical Information of China (English)

    Reza Behnood; Bagher Anvaripour; Nematollah Jaafarzadeh; Masoome Farasati

    2016-01-01

    In the recent decades oil spills in the aquatic environments are one of the major sources of environmental pollutions, which are steadily growing with the increase in oil consumption. Adsorption is a rapid and cost effective processto minimize the environmental impacts of oil spills andcleanup these pollutants. In this work, the crude oil sorption capacity was examined with raw sugarcane bagasse and acetylated sugarcane bagasse. Results show that the acetylated bagasse was significantly more oleophilic than the raw bagasse and acetylation reaction can increase bagasse oil sorption ability by about 90%. The maximum sorption capacities of acetylated bagasse were obtained about 11.3 g and 9.1 g in dry system (crude oil sorption) and oil layer sorption, respectively. The physicochemical characteristics of the sorbents such as composition, water solubility, moisture content and density were measured according to ASTM standard methods. Also Fourier transform infrared spectroscopy (FTIR) of raw and acetylated bagasse was performed to investigate the effect of acetylation on sugarcane bagasse structure.

  11. Evaluation of Lagergren Kinetics Equation by Using Novel Kinetics Expression of Sorption of Zn2+ onto Horse Dung Humic Acid (HD-HA

    Directory of Open Access Journals (Sweden)

    Bambang Rusdiarso

    2016-12-01

    Full Text Available Extraction and purification of humic acid from dry horse dung powder (HD-HA was performed successfully and the purified HD-HA was then applied as sorbent to adsorb Zn2+. Extraction and purification were performed based on procedure of Stevenson (1994 under atmospheric air. Parameters investigated in this work consist of effect of medium sorption acidity, sorption rate (ka and desorption rate constant (kd, Langmuir (monolayer and Freundlich (multilayer sorption capacities, and energy (E of sorption. The ka and kd were determined according to the kinetic model of second order sorption reaching equilibrium, monolayer sorption capacity (b and energy (E were determined according to Langmuir isotherm model, and multilayer sorption capacity (B was determined based on Freundlich isotherm model. Sorption of Zn2+ on purified HD-HA was maximum at pH 5.0. The novel kinetic expression resulted from proposed kinetic model has been shown to be more applicable than the commonly known Lagergren equation obtained from the pseudo-first order sorption model. The application of the equation revealed that the intercept of Lagergren equation, ln qe was more complex function of initial concentration of Zn2+ (a, Langmuir sorption capacity (b, and sorbed Zn2+ at equilibrium (xe.

  12. Siderophore sorption to clays.

    Science.gov (United States)

    Maurice, Patricia A; Haack, Elizabeth A; Mishra, Bhoopesh

    2009-08-01

    Siderophores are low molecular weight organic ligands exuded by some aerobic organisms and plants to acquire Fe under Fe-limited conditions. The hydroxamate siderophores may sorb to aluminosilicate clays through a variety of mechanisms depending upon the nature of the clay and of the siderophore along with solution conditions such as pH, ionic strength, and presence of metal cations. They may also affect metal binding to clays. Here, we review previous studies of siderophore sorption to aluminosilicate clays; briefly discuss how the techniques of X-ray diffractometry, Fourier-transform infrared spectroscopy, and X-ray absorption spectroscopy may be applied to such studies; review effects of siderophores on metal sorption to clays; and highlight some areas for future research.

  13. TECHNETIUM SORPTION MEDIA REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN JB; KELLY SE; ROBBINS RA; ADAMS RD; THORSON MA; HAASS CC

    2011-08-25

    This report presents information and references to aid in the selection of 99Tc sorption media for feasibility studies regarding the removal of 99Tc from Hanford's low activity waste. The report contains literature search material for sorption media (including ion exchange media) for the most tested media to date, including SuperLig 639, Reillex HPQ, TAM (Kruion), Purolite A520E and A530E, and Dowex 1X8. The U.S. Department of Energy (DOE), Office of River Protection (ORP) is responsible for management and completion of the River Protection Project (RPP) mission, which comprises both the Hanford Site tank farms and the Waste Treatment and Immobilization Plant (WTP). The RPP mission is to store, retrieve and treat Hanford's tank waste; store and dispose of treated wastes; and close the tank farm waste management areas and treatment facilities in a safe, environmentally compliant, cost-effective and energy-effective manner.

  14. KINETIC MODELING AND ISOTHERM STUDIES ON A BATCH REMOVAL OF ACID RED 114 BY AN ACTIVATED PLANT BIOMASS

    Directory of Open Access Journals (Sweden)

    N. RAJAMOHAN

    2013-12-01

    Full Text Available In this paper, the dye Acid Red 114(AR 114 was removed from aqueous solutions using Acid-Activated Eichornia Crassipes (AAEC under batch conditions. The optimum conditions for AR 114 removal were found to be pH 1.5, adsorbent dosage = 1.25 g/L of solution and equilibrium time = 3 h. The equilibrium data were evaluated for compliance with Langmuir, Freundlich and Temkin isotherms and Langmuir isotherm was found to fit well. The maximum sorption capacity was estimated as 112.34 mg/g of adsorbent. Also, adsorption kinetics of the dye was studied and the rates of sorption were found to follow pseudo-second order kinetics with good correlation (R2 ≥ 0.997.The kinetic study at different temperatures revealed that the sorption was an endothermic process. The activation energy of the sorption process was estimated as 9.722 kJ/mol.

  15. Isothermal Community College

    Science.gov (United States)

    Jones, Karen Kitchens

    2009-01-01

    Isothermal Community College (ICC) is located in Spindale, North Carolina. The college serves approximately 2,000 curriculum students every fall and spring semester and about 1,000 curriculum students in summer semesters. The Student Affairs department at ICC is divided into 10 functional areas. Over the last several years, student affairs staff…

  16. Isothermal Martensite Formation

    DEFF Research Database (Denmark)

    Villa, Matteo

    Isothermal (i.e. time dependent) martensite formation in steel was first observed in the 40ies of the XXth century and is still treated as an anomaly in the description of martensite formation which is considered as a-thermal (i.e. independent of time). Recently, the clarification of the mechanis...

  17. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive str...

  18. A Model For Non-Fickian Moisture Transfer In Wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Damkilde, Lars

    2004-01-01

    A model for non-Fickian moisture transfer in wood is presented. The model considers the transfer of water vapour separate from the transfer of bound water. These two components are linked by an equation describing the sorption on the cell wall level. Hereby, a formulation capable of describing...

  19. A Model For Non-Fickian Moisture Transfer In Wood

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Damkilde, Lars

    2004-01-01

    A model for non-Fickian moisture transfer in wood is presented. The model considers the transfer of water vapour separate from the transfer of bound water. These two components are linked by an equation describing the sorption on the cell wall level. Hereby, a formulation capable of describing kn...

  20. Gas Sorption, Diffusion, and Permeation in Nafion

    KAUST Repository

    Mukaddam, Mohsin Ahmed

    2015-12-22

    The gas permeability of dry Nafion films was determined at 2 atm and 35 °C for He, H2, N2, O2, CO2, CH4, C2H6, and C3H8. In addition, gas sorption isotherms were determined by gravimetric and barometric techniques as a function of pressure up to 20 atm. Nafion exhibited linear sorption uptake for low-solubility gases, following Henry’s law, and convex behavior for highly sorbing condensable gases, indicating rubber-like behavior at 35 °C. XRD results demonstrated that Nafion contains bimodal amorphous chain domains with average d-spacing values of 2.3 and 5.3 Å. Only helium and hydrogen showed relatively high gas permeability of 37 and 7 barrers, respectively; all other gases exhibited low permeability that decreased significantly as penetrant size increased. Dry Nafion was characterized by extraordinarily high selectivities: He/H2 = 5.2, He/CH4 = 445, He/C2H6 = 1275, He/C3H8 = 7400, CO2/CH4 = 28, CO2/C2H6 = 79, CO2/C3H8 = 460, H2/CH4 = 84, H2/C2H6 = 241, and H2/C3H8 = 1400. These high selectivities could make Nafion a potential candidate membrane material for dry feeds for helium recovery and carbon dioxide separation from natural gas and removal of higher hydrocarbons from hydrogen-containing refinery gases.

  1. SORPTION AND DESORPTION OF GLYPHOSATE IN MOLLISOLS AND ULTISOLS SOILS OF ARGENTINA.

    Science.gov (United States)

    Gómez Ortiz, Ana Maria; Okada, Elena; Bedmar, Francisco; Costa, José Luis

    2017-05-08

    In Argentina, glyphosate use has increased exponentially in the past years due to the widespread adoption of no-till management combined with genetically modified glyphosate-resistant crops. This massive use of glyphosate has created concern about its potential environmental impact. Sorption-desorption of glyphosate was studied in three Argentinean soils with contrasting characteristics. Glyphosate sorption isotherms were modeled using the Freundlich equation to estimate the sorption coefficient (Kf ). Glyphosate sorption was high and the Kf varied from 115.6 to 1612 mg (1-1/n) L(1/n) /Kg. Cerro Azul soil had the highest glyphosate sorption capacity due to a combination of factors such as higher clay content, CEC, total Fe, Al oxides and lower available phosphorous and pH. Desorption isotherms were also modeled using the Freundlich equation. In general, desorption was very low (glyphosate strongly sorbs to the soils and that it is almost an irreversible process. Anguil soil had a significant higher desorption coefficient (Kfd ) than the other soils, associated with its lower clay content and higher pH and phosphorous. Glyphosate high sorption and low desorption to the studied soils may prevent groundwater contamination. However, it may also affect its bioavailability increasing its persistence and favoring its accumulation in environment. Results of this study contribute to the knowledge and characterization of glyphosate retention in different soils. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Contributions of a compost-biochar mixture to the metal sorption capacity of a mine tailing.

    Science.gov (United States)

    Forján, R; Asensio, V; Rodríguez-Vila, A; Covelo, E F

    2016-02-01

    One technique applied to restore degraded or contaminated soils is to use amendments made of different types of waste materials, which in turn may contain metals such as Cu, Pb and Zn. For this reason, it is important to determine the capacity of the soil to retain these materials, and to compare the sorption capacity between an amended soil and another unamended soil. The aim of this study was to determine the mobility and availability of these metals in the soil after applying the amendment, and how it affected the soil's sorption capacity. Sorption isotherms were compared with the empirical models of Langmuir and Freundlich to estimate the sorption capacity. The overall capacity of the soils to sorb Cu, Pb or Zn was evaluated as the slope Kr. The amendments used in this study were a mixture made of compost and biochar in different proportions (20, 40, 60, 100 %), which were applied to the mine tailing from a settling pond from a copper mine. The mine tailing that were amended with the mixture of compost and biochar had a higher sorption capacity than the mine tailing from the unamended pond, and their sorption isotherms had a greater affinity towards Cu, Pb and Zn than the mine tailing that was studied. Therefore, the results obtained show that adding a mixture of compost and biochar favours the retention of Cu, Pb and Zn in mine tailing.

  3. Phosphate sorption-desorption characteristics in two Inceptisols and an Alfisol of Chattisgarh, India

    Institute of Scientific and Technical Information of China (English)

    A. K. DOLUI; S. S. ROY

    2005-01-01

    Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradients in physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties. From the P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were also fitted both to the Langmuir and Freundlich Equations. The mean sorption maximum values for three different soil series were: Bastar > Geedam > Mosodi. The fraction of added phosphate sorbed for the 3 series followed this same trend as did SPR; the phosphate sorption maximum and the maximum phosphate buffering capacity, which were estimated by the Langmuir isotherm; and the Freundlich constant 1/n. However, phosphate desorption, as well as the maximum recovery percent did not follow this order. The phosphate affinity constant (K) was also different following the same progression for the 3 soil series as the Freundlich constant K′, which measured sorption strength. Meanwhile, an inverse order existed for K and K′ versus the percent desorbed relative to the sorbed as well as the maximum recovery percent. In addition,significant correlation coefficients among sorption parameters of P and soil factors were found.

  4. Sorption of Arsenite onto Mackinawite Coated Sand

    Science.gov (United States)

    Gallegos, T. J.; Hayes, K. F.; Abriola, L. M.

    2004-05-01

    Arsenic contamination of groundwater is a widespread problem affecting aquifers in the United States as well as abroad. Recent strengthening of the US EPA MCL for arsenic has prompted the need for technology capable of removing both arsenite and arsenate from solution. Arsenite, the more toxic form of arsenic, is more difficult to remove from anoxic zones in the subsurface. Studies by others have demonstrated the affinity of some types of iron sulfides for arsenite, such as troilite, pyrite, amorphous iron sulfide and mackinawite. However, these studies have not provided a comprehensive investigation of the macroscopic behavior of arsenite in the presence of crystalline mackinawite in a form that can be readily applied to real-world treatment technologies. This study examines the behavior of arsenite in the presence of mackinawite coated sand. PH edge results demonstrate that arsenite sorption onto mackinawite coated sand increases with increasing pH, reaching maximum removal at pH 10. Arsenite removal, albeit slight, occurring below pH 5 is independent of pH indicative of a different removal mechanism. Isotherm studies show that at low concentrations, removal is Langmuirian in nature. Arsenite sorption abruptly converts to linear behavior at high concentrations, possibly attributed to the saturation of the monolayer. Ionic strength effects were assessed by comparing pH edge data developed for three different concentrations of NaCl background electrolyte solution. Increases in ionic strength enhance the removal of arsenite from solution, suggesting possible inner-sphere surface complexation removal mechanisms. Information gathered in this study can be used to further develop surface complexation models to describe and predict reactivity of arsenite in the presence of mackinawite coated sands in anoxic regions. Mackinawite coated sands investigated here may provide a feasible reactive medium for implementation in above-ground sorption reactors or subsurface

  5. ISOTHERMAL PYROLYSIS OF KRAFT PULP MILL SLUDGE

    Directory of Open Access Journals (Sweden)

    Syamsudin Syamsudin

    2014-12-01

    Full Text Available Kraft pulp mill sludge cake composed of rejected wood fibers and activated sludge microorganisms. With a heating value about 14 MJ/kg (dried basis, this type of biomass had a potential as an alternative energy source. Unfortunately, it had an ash content of 27.6% and a moisture content of 80%. For reducing moisture content with minimum energy consumption, a combination of mechanical dewatering and thermal drying was studied previously. Meanwhile, experiments on isothermal pyrolysis had been carried out for further improvement on ultimate and proximate analysis of solid fuel. Final mass of char obtained from pyrolysis at 500oC was not significantly different from that of 700oC, so pyrolysis was considered to be optimum at 500oC. A char obtained from pyrolysis at temperature of 500oC had a pore surface area of 77.049 m2/g (highest among other temperatures. Kinetic of isothermal pyrolysis was well represented with a first order modified volumetric model with a frequency factor of 0.782 1/s and an activation of 34.050 kJ/mol.

  6. Sorption of actinides onto nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Buchatskaya, Yulia; Romanchuk, Anna; Yakovlev, Ruslan; Kulakova, Inna [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Shiryaev, Andrei [Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry; Kalmykov, Stepan [Lomonosov Moscow State Univ., Moscow (Russian Federation). Dept. of Chemistry; Russian Academy of Sciences, Moscow (Russian Federation). Frumkin Institute of Physical Chemistry and Electrochemistry; Russian Academy of Sciences, Moscow (Russian Federation). Vernadsky Institute of Geochemistry and Analytical Chemistry

    2015-06-01

    Detonation nanodiamonds (ND) present a significant part of nanocarbons group, which could be produced on commercial scale by detonation of explosives in a closed chamber. Their unique properties of high surface area, low weight and radiation resistance make ND a prospective candidate for applications in sorption processes in radiochemistry. To study the influence of surface chemistry on sorption properties, apristine sample of ND was treated with acids and hydrogen. The surface chemistry of the samples was characterised by infrared spectroscopy, X-ray photoelectron spectroscopy and Boehm titration. The sorption properties of ND were tested fordifferent radionuclides. The sorption capacity of ND was shown to be higher than those of commonly used radionuclide sorbents like activated carbon and compariable to other members of nanocarbon group like graphene oxide and carbon nanotubes. The sorption properties were shown to be influenced by the presence of oxygen-containing groups on the surface of ND. This represents an opportunity to increase the sorption capacity of ND.

  7. Single time point isothermal drug stability experiments at constant humidity.

    Science.gov (United States)

    Tao, Jian-Lin; Zhan, Xian-Cheng; Li, Lin-Li; Lin, Bing; Jiang, Lu

    2009-03-01

    A single time point isothermal drug stability experiments at constant humidity is introduced. In the new method, kinetic parameters related to both moisture and temperature were obtained by a single pair of experiments: these related to moisture by one with a group of testing humidities and a fixed temperature, those related to temperature by the other with a group of testing temperatures and a constant humidity. By a simulation, the estimates for the kinetic parameters (E(a), m, A) obtained by the proposed method and the reported programmed humidifying and heating method were statistically evaluated and were compared with those obtained by the isothermal measurements at constant humidity. Results indicated that under the same experimental conditions, the estimates obtained by the proposed method were significantly more precise than those obtained by the reported programmed humidifying and heating method. The estimates obtained by the isothermal method at constant humidity were somewhat more precise than those obtained by the proposed method. However, the experimental period needed by the isothermal method at constant humidity was greatly longer than that needed by the proposed method. The stability of dicloxacillin sodium, as a solid state model, was investigated by the single time point isothermal drug stability experiments at constant humidity. The results indicated that the kinetic parameters obtained by the proposed method were comparable to those from the reported.

  8. SORPTION OF Ga (III ON FLEXIBLE OPEN CELL POLYURETHANE FOAM OF POLYETHER TYPE IMPREGNATED WITH TRI-N-BUTHYL PHOSPATE

    Directory of Open Access Journals (Sweden)

    Lavinia Tofan

    2007-06-01

    Full Text Available The obtained results concerning the Ga (III ion retention on flexible open cell polyurethane foam of polyether type pretreated with tri-n-butyl phosphate are presented. The influence of solution acidity, phases contact time, Ga (III concentration and solution temperature have been investigated. The parameters of Ga (III batch sorption have been optimized. On the basis of Langmuir isotherms, the sorption constants and the thermodynamic parameters, ∆G, ∆Η and ∆S have been calculated.

  9. Saturated salt method determination of hysteresis of Pinus sylvestris L. wood for 35 ºC isotherms

    Directory of Open Access Journals (Sweden)

    García Esteban, L.

    2004-12-01

    Full Text Available The saturated salts method was used in this study to quantify hysteresis in Pinus sylvestris L. wood, in an exercise that involved plotting the 35 ºC desorption and sorption isotherms. Nine salts were used, all of which establish stable and known relative humidity values when saturated in water The wood was kept at the relative humidity generated by each of these salts until the equilibrium moisture content (EMC was reached, both in the water loss or desorption, and the water uptake or sorption processes. The Guggenheim method was used to fit the values obtained to the respective curves. Hysteresis was evaluated in terms of the hysteresis coefficient, for which a mean value of 0.87 was found.

    Con este trabajo se ha cuantificado la histéresis de la madera de Pinus sylvestris L. Para ello, se han construido las isotermas de 35 ºC de adsorción y sorción, mediante el método de las sales saturadas. Se han utilizado nueve sales que cuando se saturan en agua dan lugar a unas humedades relativas estables y conocidas. La madera fue colocada bajo las distintas humedades relativas que confieren cada una de las sales hasta que alcanzaron las distintas humedades de equilibrio higroscópico, tanto en el proceso de pérdida de agua o desorción, como en el de adquisición de agua o de sorción. Los valores obtenidos fueron ajustados a las respectivas sigmoides, haciendo uso del método de Guggenheim. La valoración de la histéresis se determinó mediante el coeficiente de histéresis, obteniendo un valor medio de 0,87.

  10. The dynamic process of atmospheric water sorption in [BMIM][Ac]: quantifying bulk versus surface sorption and utilizing atmospheric water as a structure probe.

    Science.gov (United States)

    Chen, Yu; Cao, Yuanyuan; Yan, Chuanyu; Zhang, Yuwei; Mu, Tiancheng

    2014-06-19

    The dynamic process of the atmospheric water absorbed in acetate-based ionic liquid 1-butyl-3-methyl-imidazolium acetate ([BMIM][Ac]) within 360 min could be described with three steps by using two-dimensional correlation infrared (IR) spectroscopy technique. In Step 1 (0-120 min), only bulk sorption via hydrogen bonding interaction occurs. In Step 2 (120-320 min), bulk and surface sorption takes place simultaneously via both hydrogen bonding interaction and van der Waals force. In Step 3, from 320 min to steady state, only surface sorption via van der Waals force occurs. Specifically, Step 2 could be divided into three substeps. Most bulk sorption with little surface sorption takes place in Step 2a (120-180 min), comparative bulk and surface sorption happens in Step 2b (180-260 min), and most surface sorption while little bulk sorption occurs in Step 2c (260-320 min). Interestingly, atmospheric water is found for the first time to be able to be used as a probe to detect the chemical structure of [BMIM][Ac]. Results show that one anion is surrounded by three C4,5H molecules and two anions are surrounded by five C2H molecules via hydrogen bonds, which are very susceptible to moisture water especially for the former one. The remaining five anions form a multimer (equilibrating with one dimer and one trimer) via a strong hydrogen bonding interaction, which is not easily affected by the introduction of atmospheric water. The alkyl of the [BMIM][Ac] cation aggregates to some extent by van der Walls force, which is moderately susceptible to the water attack. Furthermore, the proportion of bulk sorption vs surface sorption is quantified as about 70% and 30% within 320 min, 63% and 37% within 360 min, and 11% and 89% until steady-state, respectively.

  11. Sorption of 2,4-dinitroanisole (DNAN) on lignin

    Institute of Scientific and Technical Information of China (English)

    Rabih Saad; Zorana Radovic-Hrapovic; Behzad Ahvazi; Sonia Thiboutot; Guy Ampleman; Jalal Hawari

    2012-01-01

    The present study describes the use of two commercially available lignins,namely,alkali and organosolv lignin,for the removal of 2,4-dinitroanisole (DNAN),a chemical widely used by the military and the dye industry,from water.Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin,i.e.k2 10.3 and 0.3 g/(mg.hr),respectively.In a separate study we investigated sorption of DNAN between 10 and 40℃ and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin.Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation,△H0 equaled to 14 or 80 kJ/mol.To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis,BET nitrogen adsorption-desorption and 31p NMR.Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding.The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption.31p NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin,i.e.,70% and 45%,respectively.The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.

  12. Sorption of 2,4-dinitroanisole (DNAN) on lignin.

    Science.gov (United States)

    Saad, Rabih; Radovic-Hrapovic, Zorana; Ahvazi, Behzad; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

    2012-01-01

    The present study describes the use of two commercially available lignins, namely, alkali and organosolv lignin, for the removal of 2,4-dinitroanisole (DNAN), a chemical widely used by the military and the dye industry, from water. Sorption of DNAN on both lignins reached equilibrium within 10 hr and followed pseudo second-order kinetics with sorption being faster with alkali than with organosolv lignin, i.e. k2 10.3 and 0.3 g/(mg x hr), respectively. In a separate study we investigated sorption of DNAN between 10 and 40 degrees C and found that the removal of DNAN by organosolv lignin increased from 0.8 to 7.5 mg/g but reduced slightly from 8.5 to 7.6 mg/g in the case of alkali lignin. Sorption isotherms for either alkali or organosolv lignin best fitted Freundlich equation with enthalpy of formation, deltaH0 equaled to 14 or 80 kJ/mol. To help understand DNAN sorption mechanisms we characterized the two lignins by elemental analysis, BET nitrogen adsorption-desorption and 31P NMR. Variations in elemental compositions between the two lignins indicated that alkali lignin should have more sites (O- and S-containing functionalities) for H-bonding. The BET surface area and calculated total pore volume of alkali lignin were almost 10 times greater than that of organosolv lignin suggesting that alkali lignin should provide more sites for sorption. 31P NMR showed that organosolv lignin contains more phenolic -OH groups than alkali lignin, i.e., 70% and 45%, respectively. The variations in the type of OH groups between the two lignins might have affected the strength of H-bonding between DNAN and the type of lignin used.

  13. Sorption of cesium in young till soils

    Energy Technology Data Exchange (ETDEWEB)

    Lusa, Merja; Lempinen, Janne; Ahola, Hanna; Soederlund, Mervi; Lehto, Jukka [Helsinki Univ. (Finland). Laboratory of Radiochemistry; Lahdenperae, Anne-Maj [Saanio and Riekkola Oy, Consulting Engineers, Helsinki (Finland); Ikonen, Ari T.K. [Posiva Oy, Eurajoki (Finland)

    2014-10-01

    Soil samples from three forest soil pits were examined down to a depth of approximately three metres using 1 M ammonium acetate extraction and microwave-assisted extraction with concentrated nitric acid (HNO{sub 3}), to study the binding of cesium (Cs) at Olkiluoto Island, southern Finland. Ammonium acetate was used to extract the readily exchangeable Cs fractions roughly representing the Cs fraction in soil which is available for plants. Microwave-assisted HNO{sub 3} extraction dissolves various minerals, e.g. carbonates, most sulphides, arsenides, selenides, phosphates, molybdates, sulphates, iron (Fe) and manganese (Mn) oxides and some silicates (olivine, biotite, zeolite), and reflects the total Cs concentrations. Cs was mostly found in the strongly bound fraction obtained through HNO{sub 3} extraction. The average Cs concentrations found in this fraction were 3.53 ± 0.30 mg/kg (d.w.), 3.06 ± 1.86 mg/kg (d.w.) and 1.83 ± 0.42 mg/kg (d.w.) in the three soil pits, respectively. The average exchangeable Cs found in the ammonium acetate extraction in all three sampling pits was 0.015 ± 0.008 mg/kg (d.w.). In addition, Cs concentrations in the soil solution were determined and in situ distribution coefficients (K{sub d}) for Cs were calculated. Furthermore, the in situ K{sub d} data was compared with the Cs K{sub d} data obtained using the model batch experiments. The in situ K{sub d} values were observed to fairly well follow the trend of batch sorption data with respect to soil depth, but on average the batch distribution coefficients were almost an order of magnitude higher than the in situ K{sub d} data. In situ Cs sorption data could be satisfactory fitted with the Langmuir sorption isotherm, but the Freundlich isotherm failed to fit the data. Finally, distribution coefficients were calculated by an ion exchange approach using soil solution data, the cation exchange capacity (CEC) as well as Cs to sodium (Na) and Cs to potassium (K) ion exchange selectivity

  14. Using ground and intact coal Samples to evaluate hydrocarbon fate during supercritical CO2 injection into coal beds: effects of particle size and coal moisture

    Science.gov (United States)

    Kolak, Jon; Hackley, Paul C.; Ruppert, Leslie F.; Warwick, Peter D.; Burruss, Robert

    2015-01-01

    To investigate the potential for mobilizing organic compounds from coal beds during geologic carbon dioxide (CO2) storage (sequestration), a series of solvent extractions using dichloromethane (DCM) and using supercritical CO2 (40 °C and 10 MPa) were conducted on a set of coal samples collected from Louisiana and Ohio. The coal samples studied range in rank from lignite A to high volatile A bituminous, and were characterized using proximate, ultimate, organic petrography, and sorption isotherm analyses. Sorption isotherm analyses of gaseous CO2 and methane show a general increase in gas storage capacity with coal rank, consistent with findings from previous studies. In the solvent extractions, both dry, ground coal samples and moist, intact core plug samples were used to evaluate effects of variations in particle size and moisture content. Samples were spiked with perdeuterated surrogate compounds prior to extraction, and extracts were analyzed via gas chromatography–mass spectrometry. The DCM extracts generally contained the highest concentrations of organic compounds, indicating the existence of additional hydrocarbons within the coal matrix that were not mobilized during supercritical CO2 extractions. Concentrations of aliphatic and aromatic compounds measured in supercritical CO2 extracts of core plug samples generally are lower than concentrations in corresponding extracts of dry, ground coal samples, due to differences in particle size and moisture content. Changes in the amount of extracted compounds and in surrogate recovery measured during consecutive supercritical CO2extractions of core plug samples appear to reflect the transition from a water-wet to a CO2-wet system. Changes in coal core plug mass during supercritical CO2 extraction range from 3.4% to 14%, indicating that a substantial portion of coal moisture is retained in the low-rank coal samples. Moisture retention within core plug samples, especially in low-rank coals, appears to inhibit

  15. Sorption of 4-ethylphenol and 4-ethylguaiacol by suberin from cork.

    Science.gov (United States)

    Gallardo-Chacón, Joan-Josep; Karbowiak, Thomas

    2015-08-15

    Cork shows an active role in the sorption of volatile phenols from wine. The sorption properties of 4-ethylphenol and 4-ethylguaiacol phenols in hydro-alcoholic medium placed in contact with suberin extracted from cork were especially investigated. To that purpose, suberin was immersed in model wine solutions containing several concentrations of each phenol and the amount of the compound remaining in the liquid phase was determined by SPME-GC-MS. Sorption isotherms of 4-ethylguaiacol and 4-ethylphenol by suberin followed the Henry's model. The solid/liquid partition coefficients (KSL) between the suberin and the model wine were also determined for several other volatile phenols. Suberin displayed rather high sorption capacity, which was positively correlated to the hydrophobicity of the volatile. Finally, the capacity of suberin to decrease the concentration of 4-ethylphenol and 4-ethylguaiacol was also tested in real wines affected by a Brettanomyces character. It also lead to a significant reduction of their concentration in wine.

  16. Study on Mechanisms of Cd2+ Sorption on Goethite by Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    ZHANGGUIYIN; WANGTIANZHI; 等

    1999-01-01

    A study on energy changes and mechanisms of Cd sorbed on goethite was performed using the technique of microcalorimetry.The data of the amount of Cd sorpion(Aq) and concentration of Cd in equilibrium solution(Ce),and the data of Aq and the heat effect(AH) caused by Cd2+ sorption on goethite all fitted Langmuir isotherm.The amount of heat released from Cd sorption on goethite increased with the amount of Ce or Aq.The reaction process of Cd sorption on goethite may be divided into five stages and three plateaus,depending on the variation of enthalpy change(ΔaHm) of Cd sorption with Aq,which implied three mechanisms of interaction between Cd and goethite.The experimental results showed that the microcalorimetry may be useful for determination of microcalorie variation in soil.

  17. [Sorption-desorption of phosphate in wastewater by hydrous iron oxide].

    Science.gov (United States)

    Xiang, Xue-Min; Liu, Ying; Zhou, Ji-Ti; Wang, Ren

    2008-11-01

    FeCl3 was used t o prepare hydrous iron oxide (HIO) as a n absorbent for phosphate (P) sorption and desorption study. The results showed that as pH decreased, the sorption capacity of HIO increased, and the sorption kinetics followed the second-order model, and the sorption isotherm could be fitted by the Langmuir equation. A 50 g/L NaOH solution was used for desorption of P from HIO, and the desorption rate could be reached over 98% . No relation was found between desorption rate and adsorption capacity. Based on above results, HIO was applied to adsorption of P from supernatant of sludge thickener, and after desorption, more than 90% of P was recovered. According to the results obtained, an effective system for P removal and recovery from municipal wastewater was suggested, which includes the following processes: adsorption, desorption, regeneration of HIO, and of recovery of P from P-rich desorption solution.

  18. Phosphorus isothermal adsorption characteristics of mulch of bioretention

    Directory of Open Access Journals (Sweden)

    Mei Ying

    2012-01-01

    Full Text Available This study aims to identify mulch of bioretention which has high phosphorus sorption capacity. The phosphorus adsorption characteristics of five types of mulch of bioretention are studied by three isothermal adsorption experiments. Results show that the Langmuir eqution is suitable for describing absorption characteristics of five types of mulch. The positive values of Gibbs free energy for phosphorus indicate that the phosphorus biosorption by five mulches is a non-spontaneous process, and the values of mean sorption free energy of mulch are less than 8 kJ/mol, which proves that the adsorption process can be dominated by physical forces. The vermiculite is the better mulch of bioretention based on high phosphorus removal capacity.

  19. Sorption of perfluorinated compounds from contaminated water to activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Mona C.; Boerresen, Marion H. [Norwegian Geotechnical Inst. (NGI), Oslo (Norway); Schlabach, Martin [Norwegian Inst. for Air Research, Kjeller (Norway); Cornelissen, Gerard [Norwegian Geotechnical Inst. (NGI), Oslo (Norway); Dept. of Applied Environmental Sciences (ITM), Stockholm Univ. (Sweden)

    2010-03-15

    Introduction: Perfluorinated compounds (PFC) are toxic and bioaccumulative compounds that are ubiquitous in the environment. It is important to develop effective techniques to remove PFC from water. This study is the first to investigate sorption of PFC to activated carbon (AC) at environmentally relevant nanogram per liter concentrations. Methods: Batch AC sorption isotherms were measured for water from a contaminated groundwater well, for three perfluorosulfonates and five perfluoroacetic acids. Results: For perfluorooctane sulfonate and perfluorooctanoic acid Freundlich sorption coefficients, log K{sub iF} for powdered activated carbon (PAC) were 4.0 and 3.8 (ng/g)(ng/L){sup -n}, respectively, and for granular activated carbon (GAC) were 2.7 and 2.3 (ng/g)(ng/L){sup -n}, respectively. Sorption was nonlinear, with Freundlich n coefficients generally around 0.5. The K{sub iF} on both GAC and PAC were PFC chain-length dependant, with increasing number of carbon yielding increasing K{sub iF}. This chain-length dependence appeared stronger for perfluorosulfonates than for perfluoroacetic acids. Tests with short (10 min) adsorption times still yielded substantial PFC removal (20-40% for GAC, 60-90% for PAC) and revealed that AC is probably suitable for PFC removal in flow-through systems. A perfluorinated polymer, Teflon, was also tested as a PFC removal agent but proved not to be effective for PFC-contaminated water purification. (orig.)

  20. The effect of inositol hexaphosphate on cadmium sorption to gibbsite.

    Science.gov (United States)

    Ruyter-Hooley, Maika; Larsson, Anna-Carin; Johnson, Bruce B; Antzutkin, Oleg N; Angove, Michael J

    2016-07-15

    Oxides, hydrous oxides and hydroxides of aluminium and iron are important in determining the availability of trace and heavy metals in soil systems. The presence of complexing anions is also known to affect the binding of these metals in soils. Since organophosphates, such as inositol hexaphosphate (IP6), are present in most soil systems they are expected to affect the nature of the interaction between metal ions and metal (hyr)oxides. Both adsorption edge and isotherm experiments were conducted on Cd(II)-gibbsite and Cd(II)-IP6-gibbsite systems. In addition, solid-state (31)P MAS NMR measurements were performed on the ternary system. All results were used to develop Extended Constant Capacitance surface complexation models of both the Cd(II)-gibbsite and IP6-Cd(II)-gibbsite sorption systems. The presence of IP6 significantly increased sorption of Cd(II) to gibbsite below pH 8 especially at higher concentrations of Cd(II) and IP6. The (31)P MAS NMR spectra, together with surface complexation modeling, indicated the presence of two outer-sphere ternary complexes with the first, [(SOH2)3(3+)(LHCd)(9-)](6-), important at relatively low concentrations, while the second, [SLH3(8-)Cd(2+)](6-), dominated sorption at higher sorbate concentrations. Thus the presence of organophosphates in soil systems increases sorption and may therefore decrease the availability of trace and heavy metals to plants. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Sorption and desorption of silver ions by bentonite clays.

    Science.gov (United States)

    Constantino, Leonel Vinicius; Quirino, Juliana Nunes; Monteiro, Alessandra Maffei; Abrão, Taufik; Parreira, Paulo Sérgio; Urbano, Alexandre; Santos, Maria Josefa

    2017-04-01

    Anthropogenic activities have increased the concentration of metal species in the environment. The toxicity of silver ions to aquatic and terrestrial organisms has required monitoring by analytical methods, besides actions to promote its control as pollutant. Sorption and desorption processes are directly related to the mobility and availability of metal ions in the environment. In this context, clay minerals can be used for pre-concentration, removal and recovery of silver ions from aqueous solution. Herein, two bentonite clays (BaVC-1 and SWy-2) were characterised and applied to investigate the sorption and desorption of silver ions. Isotherms were fitted to the dual-mode Langmuir-Freundlich model to qualify and quantify sorption sites and evaluate the mobilisation process. The maximum sorption capacity was 743 and 849 meq kg(-1) for BaVC-1 and SWy-2, respectively. Hysteresis index (HI) and mobilisation factor (MF) suggest that the desorption of silver ions in BaVC-1 is about four times more conducive compared to that in SWy-2, although both materials have demonstrated a great potential for Ag(+) pre-concentration from aqueous solutions.

  2. Sorption product heat pump

    Energy Technology Data Exchange (ETDEWEB)

    Antonini, G.; Francois, O.; Gendarme, J.P.; Guilleminot, J.J.; Meunier, F.

    1988-07-15

    A continuous operating, and thus with enhanced performance, heat pump is presented. In this heat pump, the heat transfer between the hot source and the output system or network is realized through a solid adsorbent-refrigerant couple having endothermal desorption properties and exothermal adsorption or absorption properties. The sorption products are carried in a closed cycle movement between the two parts of the reactor. Each side of the reactor is assuming always the same function and the thermal inertia have to be overcome only when starting the reactor.

  3. Characteristics and influencing factors of tetrachloroethylene sorption-desorption on soil and its components.

    Science.gov (United States)

    Qiu, Zhaofu; Yang, Weiwei; He, Long; Zhao, Zhexuan; Lu, Shuguang; Sui, Qian

    2016-02-01

    To investigate the effects of soil structure, soil organic carbon (SOC), minerals, initial tetrachloroethylene (PCE) concentration (C0), and ionic strength (Ci) on PCE sorption-desorption, six types of soil were adopted as adsorbents, including two types of natural soil and four types of soil with most of the "soft carbon" pre-treated by H2O2 or with all SOC removed from the original soil by 600 °C ignition. The results showed that all of the sorption-desorption isotherms of PCE were non-linear within the experimental range, and the H2O2-treated samples exhibited higher non-linear sorption isotherms than those of the original soils. The hysteresis index of PCE sorption to original soil is less pronounced than that of the H2O2-treated and 600 °C-heated samples due to the entrapment of sorbate molecules in the "hard carbon" domain, together with the meso- and microporous structures within the 600 °C-heated samples. Both SOC and minerals have impacts on the sorption-desorption of PCE, and the sorption-desorption contribution rate of minerals increased with decreasing SOC content. C0 has almost no influence on the sorption to minerals of the soils, but the contribution rate of minerals decreased with increasing C0 in the desorption stage. As a result of the salting-out effect, PCE sorption capacity was increased by increasing Ci, especially when Ci ≥ 0.1 M. Moreover, desorption increased and hysteresis weakened with increasing Ci, except for the 600 °C-heated samples. In addition, no significant effect of Ci on desorption of PCE and no hysteresis was observed in this experimental range for the 600 °C-heated samples.

  4. Sorption of atrazine, acetochlor, and 2,4-D by hardwood-derived biochar

    Science.gov (United States)

    Gonzalez, J. M.; Shipitalo, M. J.

    2016-12-01

    Offsite transport of herbicides and other agricultural pesticides to streams and other bodies of water can adversely impact drinking water supplies and aquatic ecology. Atrazine, acetochlor, and 2,4-D are herbicides commonly used to control weeds in maize (Zea mays) and soybean (Glycine max), the dominant crops in the U.S. Midwest. Unfortunately, these materials are frequently detected at high concentrations in surface runoff and subsurface drainage, especially when rainstorms occur shortly after their application. Thus, edge-of-field technologies employing effective sorbents to remove pesticides in water are needed to reduce this concern. In this study, we investigated the sorption of atrazine, acetochlor, and 2,4-D by a hardwood-derived biochar. Sorption kinetics and isotherms were determined for each pesticide using concentrations ranging from 5 to 100 ug L-1. The results from the kinetic sorption studies were fitted to pseudo first- and second-order reaction models and demonstrated that sorption was fast; in less than an hour > 90% of the added pesticides were sorbed and after 24 hours up to 100% was removed. The pH of the suspensions after the sorption kinetic and isotherm studies was 8.26 ± 0.51. Thus, because of the nature of the biochar and the pesticides used in this study, hydrophobic interactions appear to be the main mechanism of sorption. Furthermore, since the sorption was fast, we hypothesize that sorption occurred on the surface of biochar. The information from this study can be used to develop agricultural best management practices to remove pesticides in water.

  5. Polycyclic aromatic hydrocarbon (PAH) sorption process to the "black carbon" (BC) component in river sediments

    Science.gov (United States)

    Zhang, Jing; Séquaris, Jean-Marie; Narres, Hans-Dieter; Vereecken, Harry; Klumpp, Erwin

    2010-05-01

    The importance of BC for the long term sequestration of organic carbon is actually discussed for mitigating climate change. In this context, the role of BC as a filter or source of nutrients or toxic chemicals is questioned. The fate of polycyclic aromatic hydrocarbons (PAHs) is especially concerned. In this study, we have investigated the binding of PAH compounds, pyrene and phenanthrene, to Yangtze River sediments. For this purpose, the PAHs sorption to pristine and preheated sediments at 375°C was studied, which allow discriminating the contributions of amorphous organic carbon (AOC) and black carbon (BC) fractions to the PAH sorption extent. An analytical procedure for the determination of PAHs in the solution phase of the batch experiments has been developed with fluorescence spectroscopy. The PAHs sorption isotherms to pristine sediments were fitted by Freundlich and composite models as linear Langmuir model (LLM) and linear Polanyi-Dubinin-Manes model (LPDMM). The sequential application of composite models LLM and LPDMM to the sorption isotherms allows assessing the partition of PAHs into AOC and its nonlinear adsorption in the porous structure of BC. The modelling results indicate that the PAHs sorption to minor BC component of sediments (molecular sieving plays an important role in the competitive PAHs sorption in a multi-solute system. J. Zhang, Ph.D. Dissertation, RWTH Aachen, Germany, 2010 J. Zhang et al., Effects of organic carbon and clay fractions on the pyrene sorption and distribution in Yangtze River sediments (submitted). J. Zhang et al., Pyrene and phenanthrene sorptions to Yangtze River sediments and their components in single and binary solute systems (submitted)

  6. Water sorption-induced crystallization, structural relaxations and strength analysis of relaxation times in amorphous lactose/whey protein systems

    OpenAIRE

    Fan, Fanghui; Mou, Tian; Nurhadi, Bambang; Roos, Yrjö H.

    2016-01-01

    Water sorption-induced crystallization, α-relaxations and relaxation times of freeze-dried lactose/whey protein isolate (WPI) systems were studied using dynamic dewpoint isotherms (DDI) method and dielectric analysis (DEA), respectively. The fractional water sorption behavior of lactose/WPI mixtures shown at aw ≤ 0.44 and the critical aw for water sorption-related crystallization (aw(cr)) of lactose were strongly affected by protein content based on DDI data. DEA results showed that the α-rel...

  7. Sorption of Cu2+ and Co2+ from aqueous solutions onto sepiolite: an equilibrium, kinetic and thermodynamic study

    Directory of Open Access Journals (Sweden)

    SLAVICA LAZAREVIĆ

    2011-01-01

    Full Text Available The efficiency of natural sepiolite for the removal of Cu2+ and Co2+ from aqueous solution was determined using the batch method. The sorption experiments were performed as a function of the initial metal concentration, the equilibration time and temperature. Thermodynamic parameters, such as enthalpy, free energy and entropy, were calculated from the temperature dependent sorption isotherms and these values showed that the sorption of the investigated metals onto sepiolite was endothermic. The pseudo-second order kinetic model provides the best correlation of the experimental kinetic data.

  8. Sorption characteristics of pesticides on matrix substrates used in biopurification systems.

    Science.gov (United States)

    De Wilde, Tineke; Spanoghe, Pieter; Ryckeboer, Jaak; Jaeken, Peter; Springael, Dirk

    2009-03-01

    On-farm biopurification systems were developed to remove pesticides from contaminated water generated at the farmyard. An important process in the system's efficiency is the sorption of pesticides to the substrates used in the biopurification systems. The composition and type of material present in the biobed are crucial for retention of chemicals. This study investigated the sorption of linuron, isoproturon, metalaxyl, isoxaben, bentazon and lenacil on substrates commonly used in a biopurification system, i.e. cow manure, straw, willow chopping, soil, coconut chips, garden waste compost, and peat mix. Linear, Freundlich, and Langmuir sorption isotherms were fitted to the obtained data. The best fit was obtained with the Freundlich model. More immobile pesticides (i.e. linuron and isoxaben) tended to associate with the organic substrate, while more mobile pesticides partition in the water (i.e. bentazon). According to sorption capacity, the substrates could be classified as peat mix > compost, coco chips, straw > cow manure, willow chopping > sandy loam soil. Sorption capacity was positively correlated with the organic carbon content, CaO and the cation exchange capacity. Furthermore, no significant differences in sorption could be found between technical and formulated isoproturon and bentazon. Moreover, the individual sorption coefficient K(d) was additive, which means that individual sorption coefficients can be used to calculate the sorption coefficients of a mixture of substrates. What concerns the mutual interaction of pesticides it could be observed that the sorption of linuron and metalaxyl was significantly lower in combination with isoproturon and bentazon, while the latter pesticides were not influenced by the presence of linuron and metalaxyl. As guidelines, firstly, it could be stated that using the most sorbing materials such as peat mix, might significantly increase the biopurification systems efficiency. Secondly, the treatment of very mobile

  9. Moisture conditions in buildings

    DEFF Research Database (Denmark)

    Rode, Carsten

    2012-01-01

    Growth of mould requires the presence of moisture at a certain high level. In a heated indoor environment such moisture levels occur only if there is a reason for the moisture supply. Such moisture can come from the use of the building, because of malfunctioning constructions, or it can be the re......Growth of mould requires the presence of moisture at a certain high level. In a heated indoor environment such moisture levels occur only if there is a reason for the moisture supply. Such moisture can come from the use of the building, because of malfunctioning constructions, or it can...

  10. On the zinc sorption by the Serbian natural clinoptilolite and the disinfecting ability and phosphate affinity of the exhausted sorbent.

    Science.gov (United States)

    Stojakovic, Djordje; Hrenovic, Jasna; Mazaj, Matjaz; Rajic, Nevenka

    2011-01-15

    The Serbian natural zeolite is moderately effective in removing the zinc(II) ions from aqueous solutions. At 298 K the sorption capacity varies from 13 to 26% for the initial Zn(II) solution concentration of 100 and 600 mg Zndm(-3), respectively. The sorption isotherm at 298-338 K is best represented by the Langmuir model and the sorption kinetics by the pseudo-second-order model. The sorption involves a combination of film diffusion, intra-particle diffusion, and a chemical cation-exchange between the Na(+) ions of clinoptilolite and Zn(2+) ions. The sorption was found to be endothermic and spontaneous in the 298-338 K range. The exhausted sorbent can remove phosphate ions and it exhibits an excellent antibacterial activity towards Acinetobacter junii. By dehydration at about 500 °C it transforms to a ZnO-containing product featuring nano-sized wurtzite ZnO particles widespread over the clinoptilolite surface.

  11. Removal of basic (Methylene Blue) and acid (Egacid Orange) dyes from waters by sorption on chemically treated wood shavings.

    Science.gov (United States)

    Janos, Pavel; Coskun, Sezen; Pilarová, Vera; Rejnek, Jaroslav

    2009-02-01

    Spruce wood shavings from Picea abies were used for an adsorptive removal of both basic as well as acid dyes from waters. The sorption properties of the sorbents were modified with HCl, Na(2)CO(3) and Na(2)HPO(4). The treatment of the wood sorbents with alkaline carbonate solution as well as with phosphate solution increased the sorption ability for the basic dye (Methylene Blue), whereas the treatment with mineral acid decreased the sorption ability for Methylene Blue to some extent. The opposite is true for the sorption of the acid dye--Egacid Orange. The maximum sorption capacities estimated from the Langmuir-Freundlich isotherms ranged from 0.060 to 0.165 mmol g(-1) for Methylene Blue, and from 0.045 to 0.513 mmol g(-1) for Egacid Orange. The basic dye sorption decreased at low pH values in accordance with a presupposed ion-exchange mechanism of the sorption. The sorption of acid dye, on the other hand, decreased with increasing pH. The presence of inorganic salts as well as surfactants exhibited only minor effects on the dye sorption.

  12. Effect of hydrolyzed whey protein on surface morphology, water sorption, and glass transition temperature of a model infant formula.

    Science.gov (United States)

    Kelly, Grace M; O'Mahony, James A; Kelly, Alan L; O'Callaghan, Donal J

    2016-09-01

    Physical properties of spray-dried dairy powders depend on their composition and physical characteristics. This study investigated the effect of hydrolyzed whey protein on the microstructure and physical stability of dried model infant formula. Model infant formulas were produced containing either intact (DH 0) or hydrolyzed (DH 12) whey protein, where DH=degree of hydrolysis (%). Before spray drying, apparent viscosities of liquid feeds (at 55°C) at a shear rate of 500 s(-1) were 3.02 and 3.85 mPa·s for intact and hydrolyzed infant formulas, respectively. On reconstitution, powders with hydrolyzed whey protein had a significantly higher fat globule size and lower emulsion stability than intact whey protein powder. Lactose crystallization in powders occurred at higher relative humidity for hydrolyzed formula. The Guggenheim-Anderson-de Boer equation, fitted to sorption isotherms, showed increased monolayer moisture when intact protein was present. As expected, glass transition decreased significantly with increasing water content. Partial hydrolysis of whey protein in model infant formula resulted in altered powder particle surface morphology, lactose crystallization properties, and storage stability.

  13. Streptococcus suis sorption on agricultural soils: role of soil physico-chemical properties.

    Science.gov (United States)

    Zhao, Wenqiang; Liu, Xing; Huang, Qiaoyun; Cai, Peng

    2015-01-01

    Understanding pathogen sorption on natural soil particles is crucial to protect public health from soilborne and waterborne diseases. Sorption of pathogen Streptococcus suis on 10 agricultural soils was examined, and its correlations with soil physico-chemical properties were also elucidated. S. suis sorption isotherms conformed to the linear equation, with partition coefficients (Ks) ranging from 12.7 mL g(-1) to 100.1 mL g(-1). Bacteria were observed to sorb on the external surfaces of soil aggregates by scanning electron microscopy. Using Pearson correlation and linear regression analysis, solution pH was found to have significant negative correlations with Ks. Stepwise multiple regression and path analysis revealed that pH and cation exchange capacity (CEC) were the main factors influencing sorption behaviors. The obtained overall model (Ks=389.6-45.9×pH-1.3×CEC, R(2)=0.943, PKs values. However, the variability in Ks was less dependent on soil organic matter, specific surface area, soil texture and zeta potential, probably due to the internal-surface shielding phenomenon of soil aggregates. Additionally, the sorption trends cannot be interpreted by interaction energy barriers calculated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, suggesting the limits of DLVO theory in describing pathogen sorption on natural soils. Our results also indicated soil pH and CEC should be preferentially considered when modeling S. suis sorption process.

  14. Ammonia-nitrogen and phosphates sorption from simulated reclaimed waters by modified clinoptilolite.

    Science.gov (United States)

    Huo, Hanxin; Lin, Hai; Dong, Yingbo; Cheng, Huang; Wang, Han; Cao, Lixia

    2012-08-30

    This paper presents the investigation of the ammonia-nitrogen and phosphates sorption from simulated reclaimed wastewater by modified clinoptilolite. The results showed that the modified clinoptilolite has a high sorption efficiency and removal performance. The ammonia-nitrogen and phosphates removal rate of the modified clinoptilolite reached to 98.46% and 99.80%, respectively. The surface of modified clinoptilolite became loose and some pores appeared, which enlarged the specific surface area; the contents of Na and Fe increased, and the contents of Ca and Mg decreased. The modified clinoptilolite possesses rapid sorption and slow balance characteristics and ammonia-nitrogen and phosphates sorption is more consistent with the Langmuir isotherm model. The adsorption kinetics of ammonia-nitrogen and phosphates follows the Elovich adsorption dynamics equation, which describes the sorption of ammonia-nitrogen and phosphates in aqueous solution as mainly a chemical sorption. Results from the thermodynamics experiment involving ammonia-nitrogen and phosphates sorption reveal that the process is a spontaneous and endothermic process, and is mainly driven by entropy effect.

  15. Modeling sorption of neutral organic compound mixtures to simulated aquifer sorbents with pseudocompounds.

    Science.gov (United States)

    Joo, Jin Chul; Shackelford, Charles D; Reardon, Kenneth F

    2013-01-01

    The feasibility of the ideal adsorbed solution theory (IAST) in reducing the complexity associated with predicting the sorption behaviors of 12 neutral organic compounds (NOCs) contained in complex mixtures as a fewer number (four to six) of pseudocompounds (groups of compounds) to simulated aquifer sorbents was investigated. All sorption isotherms from individual- and multiple-pseudocompound systems were fit reasonably well ( ≥ 0.953) by the Freundlich sorption model over the range of aqueous concentrations evaluated (i.e., ≤200 μmol L). The presence and magnitude of mutual competition among pseudocompounds varied depending on the composition of the mixtures (i.e., concentrations and polarities of pseudocompounds) and the properties of sorbents (i.e., the fraction of organic carbon and the availability of hydrophilic specific sorption sites). Finally, comparisons between the IAST-based predictions with individual-pseudocompound sorption parameters and experimentally measured data revealed that the accuracy in predicting the sorption behaviors of several NOCs in terms of a fewer number of pseudocompounds decreased with increasing deviations from the assumption of equal and ideal competition in the IAST (i.e., differential availability of sorption sites and nonideal competitions among pseudocompounds).

  16. Sorption of basic and acid dyes from aqueous solutions onto oxihumolite.

    Science.gov (United States)

    Janos, Pavel; Sedivý, Pavel; Rýznarová, Milena; Grötschelová, Sylvie

    2005-05-01

    Naturally occurring kind of weathered and oxidised young brown coal called oxihumolite was used for an adsorptive removal of basic (Methylene Blue, Malachite Green) as well as acid (Egacid Orange, Midlon Black) dyes from waters. It was shown that both kinds of dyes can be sorbed onto oxihumolite. The maximum sorption capacities determined from the parameters of Langmuir isotherms ranged from 0.070 mmol g-1 (for Midlon Black) to 0.278 mmol g-1 (for Malachite Green) and did not differ significantly for basic and acid dyes. The dye sorption (except of Midlon Black) increased in the presence of inorganic salt. Non-ionic surfactants, and surfactants bearing the same charge as the dye exhibited only a minor effect on the dye sorption, whereas oppositely charged surfactants enhanced the dye sorption to a certain extent. The pH value of the aqueous phase exhibited rather pronounced effect on the sorption of acid dyes causing a suppression of the sorption with increasing pH. The sorption of basic dyes, on the other hand, remained almost unchanged in the examined pH range. Oxihumolite is recommended for the treatment of acid wastewaters because of its limited stability in alkaline aqueous solutions.

  17. Using polyacrylate-coated SPME fibers to quantify sorption of polar and ionic organic contaminants to dissolved organic carbon.

    Science.gov (United States)

    Haftka, Joris J-H; Scherpenisse, Peter; Jonker, Michiel T O; Hermens, Joop L M

    2013-05-07

    A passive sampling method using polyacrylate-coated solid-phase microextraction (SPME) fibers was applied to determine sorption of polar and ionic organic contaminants to dissolved organic carbon (DOC). The tested contaminants included pharmaceuticals, industrial chemicals, hormones, and pesticides and represented neutral, anionic, and cationic structures. Prior to the passive sampler application, sorption of the chemicals to the fibers was characterized. This was needed in order to accurately translate concentrations measured in fibers to freely dissolved aqueous concentrations during the sorption tests with DOC. Sorption isotherms of neutral compounds to the fiber were linear, whereas isotherms of basic chemicals covered a nonlinear and a linear range. Sorption of acidic and basic compounds to the fiber was pH-dependent and was dominated by sorption of the neutral sorbate species. Fiber- and DOC-water partition coefficients of neutral compounds were both linearly related to octanol-water partition coefficients (log Kow). The results of this study show that polyacrylate fibers can be used to quantify sorption to DOC of neutral and ionic contaminants, having multiple functional groups and spanning a wide hydrophobicity range (log Kow = 2.5-7.5).

  18. Equilibrium, kinetic and thermodynamic studies for sorption of Ni (II from aqueous solution using formaldehyde treated waste tea leaves

    Directory of Open Access Journals (Sweden)

    Jasmin Shah

    2015-05-01

    Full Text Available The sorption characteristic of Ni (II from aqueous solution using formaldehyde treated waste tea leaves as a low cost sorbent has been studied. The effect of pH, contact time, sorbent dose, initial metal ion concentration and temperature were investigated in batch experiments. The equilibrium data were fitted into four most common isotherm models; Freundlich, Langmuir, Tempkin and Dubinin–Radushkevich (D–R. The Langmuir model described the sorption isotherm best with maximum monolayer sorption capacity of 120.50 mg g−1. Four kinetic models, pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich were employed to explain the sorption mechanism. The kinetics of sorption data showed that the pseudo-second-order model is the best with correlation coefficient of 0.9946. The spontaneous and exothermic nature of the sorption process was revealed from thermodynamic investigations. The effect of some common alkali and alkaline earth metal ions were also studied which showed that the presence of these ions have no effect on the sorption of Ni (II. The results showed that waste tea leaves have the potential to be used as a low cost sorbent for the removal of Ni (II from aqueous solutions.

  19. Setting up the drying regimes based on the theory of moisture migration during drying

    Science.gov (United States)

    Vasić, M.; Radojević, Z.

    2016-08-01

    Drying is energy intensive process which has important effect on the quality of the clay tiles that are dried commercially. Chamber and tunnel dryers are constantly improving. Better technical equipment and operational strategies have lead to higher quality of the dried clay products. The moisture migration during isothermal drying process can be visually traced on the curve that represents the relationship between variable effective moisture diffusivity (MR) with time (t). Proposed non isothermal drying regimes were consisted from several isothermal segments. For the first time, the choice of isothermal segments specification and its duration was not specified by experience or by trial-and-error method. It was detected from the isothermal curves Deff - MR in accordance with the theory of moisture migration during drying. Proposed drying regimes were tested. Clay roofing tiles were dried without cracks. Dried clay roofing tiles has satisfied all requirements defined in EN 1304 norm related to the shape regularity and mechanical properties.

  20. A Universal Isotherm Model to Capture Adsorption Uptake and Energy Distribution of Porous Heterogeneous Surface

    KAUST Repository

    Ng, Kim Choon

    2017-08-31

    The adsorbate-adsorbent thermodynamics are complex as it is influenced by the pore size distributions, surface heterogeneity and site energy distribution, as well as the adsorbate properties. Together, these parameters defined the adsorbate uptake forming the state diagrams, known as the adsorption isotherms, when the sorption site energy on the pore surfaces are favorable. The available adsorption models for describing the vapor uptake or isotherms, hitherto, are individually defined to correlate to a certain type of isotherm patterns. There is yet a universal approach in developing these isotherm models. In this paper, we demonstrate that the characteristics of all sorption isotherm types can be succinctly unified by a revised Langmuir model when merged with the concepts of Homotattic Patch Approximation (HPA) and the availability of multiple sets of site energy accompanied by their respective fractional probability factors. The total uptake (q/q*) at assorted pressure ratios (P/P s ) are inextricably traced to the manner the site energies are spread, either naturally or engineered by scientists, over and across the heterogeneous surfaces. An insight to the porous heterogeneous surface characteristics, in terms of adsorption site availability has been presented, describing the unique behavior of each isotherm type.

  1. Sorption of vanadium (V) onto natural soil colloids under various solution pH and ionic strength conditions.

    Science.gov (United States)

    Luo, Xiuhua; Yu, Lin; Wang, Changzhao; Yin, Xianqiang; Mosa, Ahmed; Lv, Jialong; Sun, Huimin

    2017-02-01

    Batch sorption kinetics and isothermal characteristics of V(V) were investigated on three natural soil colloids (manual loessial soil colloid (MSC), aeolian sandy soil colloid (ASC), and cultivated loessial soil colloid (CSC)) under various solution pH and ionic strength (IS) conditions. Colloids were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). AFM micrographs showed CSC with an aggregated shape with larger particle diameter as compared with ASC and MSC. XRD spectra revealed the presence of different minerals in natural soil colloids including biotite, kaolinite, calcite and quartz, which might contribute to sorption process. The sorption ability decreased with increase of colloidal particle size. The sorption was mainly attributed to complexation by active carboxylate and alcohol groups of colloidal components. Sorption kinetics and isotherms of V(V) onto natural soil colloids were best fitted with Pseudo-second-order and Freundlich models. Langmuir model indicated that sorption capacity of MSC and ASC was comparable (285.7 and 238.1 mg g(-1)); however, CSC exhibited the lowest sorption capacity (41.5 mg g(-1)) due to its larger particle diameter and aggregated shape. The maximum V(V) sorption capacity reached plateau values at a solution pH ranged between 5.0 and 9.0 for MSC and ASC, and 6.0-8.0 for CSC. Sorption capacity of V(V) onto natural soil colloids decreased with increasing IS. Based on result of this study we can conclude that sorption of V(V) onto natural soil colloids is pH- and IS-dependent. These findings provide insights on the remediation of vanadium-contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Sorption-desorption of imidacloprid onto a lacustrine Egyptian soil and its clay and humic acid fractions.

    Science.gov (United States)

    Kandil, Mahrous M; El-Aswad, Ahmed F; Koskinen, William C

    2015-01-01

    Sorption-desorption of the insecticide imidacloprid 1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine onto a lacustrine sandy clay loam Egyptian soil and its clay and humic acid (HA) fractions was investigated in 24-h batch equilibrium experiments. Imidacloprid (IMDA) sorption-desorption isotherms onto the three sorbents were found to belong to a non-linear L-type and were best described by the Freundlich model. The value of the IMDA adsorption distribution coefficient, Kd(ads), varied according to its initial concentration and was ranged 40-84 for HA, 14-58 for clay and 1.85-4.15 for bulk soil. Freundlich sorption coefficient, Kf(ads), values were 63.0, 39.7 and 4.0 for HA, clay and bulk soil, respectively. The normalized soil Koc value for imidacloprid sorption was ∼800 indicating its slight mobility in soils. Nonlinear sorption isotherms were indicated by 1/n(ads) values imidacloprid sorption process with all tested sorbents. Gibbs free energy (ΔG) values indicated a spontaneous and physicosorption process for IMDA and a more favorable sorption to HA than clay and soil. In conclusion, although the humic acid fraction showed the highest capacity and affinity for imidacloprid sorption, the clay fraction contributed to approximately 95% of soil-sorbed insecticide. Clay and humic acid fractions were found to be the major two factors controlling IMDA sorption in soils. The slight mobility of IMDA in soils and the hysteresis phenomenon associated with the irreversibility of its sorption onto, mainly, clay and organic matter of soils make its leachability unlikely to occur.

  3. Sorption selectivity of birnessite particle edges: a d-PDF analysis of Cd(ii) and Pb(ii) sorption by δ-MnO2 and ferrihydrite.

    Science.gov (United States)

    van Genuchten, Case M; Peña, Jasquelin

    2016-08-10

    Birnessite minerals (layer-type MnO2), which bear both internal (cation vacancies) and external (particle edges) metal sorption sites, are important sinks of contaminants in soils and sediments. Although the particle edges of birnessite minerals often dominate the total reactive surface area, especially in the case of nanoscale crystallites, the metal sorption reactivity of birnessite particle edges remains elusive. In this study, we investigated the sorption selectivity of birnessite particle edges by combining Cd(ii) and Pb(ii) adsorption isotherms at pH 5.5 with surface structural characterization by differential pair distribution function (d-PDF) analysis. We compared the sorption reactivity of δ-MnO2 to that of the nanomineral, 2-line ferrihydrite, which exhibits only external surface sites. Our results show that, whereas Cd(ii) and Pb(ii) both bind to birnessite layer vacancies, only Pb(ii) binds extensively to birnessite particle edges. For ferrihydrite, significant Pb(ii) adsorption to external sites was observed (roughly 20 mol%), whereas Cd(ii) sorption was negligible. These results are supported by bond valence calculations that show comparable degrees of saturation of oxygen atoms on birnessite and ferrihydrite particle edges. Therefore, we propose that the sorption selectivity of birnessite edges follows the same order of that reported previously for ferrihydrite: Ca(ii) < Cd(ii) < Ni(ii) < Zn(ii) < Cu(ii) < Pb(ii).

  4. Single-solute and bisolute sorption of phenol and trichloroethylene from aqueous solution onto modified montmorillonite and application of sorption models.

    Science.gov (United States)

    Wu, C D; Wang, L; Hu, C X; He, M H

    2013-01-01

    The single-solute and bisolute sorption behaviour of phenol and trichloroethylene, two organic compounds with different structures, onto cetyltrimethylammonium bromide (CTAB)-montmorillonite was studied. The monolayer Langmuir model (MLM) and empirical Freundlich model (EFM) were applied to the single-solute sorption of phenol or trichloroethylene from water onto monolayer or multilayer CTAB-montmorillonite. The parameters contained in the MLM and EFM were determined for each solute by fitting to the single-solute isotherm data, and subsequently utilized in binary sorption. The extended Langmuir model (ELM) coupled with the single-solute MLM and the ideal adsorbed solution theory (IAST) coupled with the single-solute EFM were used to predict the binary sorption of phenol and trichloroethylene onto CTAB-montmorillonite. It was found that the EFM was better than the MLM at describing single-solute sorption from water onto CTAB-montmorillonite, and the IAST was better than the ELM at describing the binary sorption from water onto CTAB-montmorillonite.

  5. Pentachlorophenol sorption in nylon fiber and removal by immobilized Rhizopus oryzae ENHE.

    Science.gov (United States)

    León-Santiestebán, Hugo; Meraz, Mónica; Wrobel, Kazimierz; Tomasini, Araceli

    2011-06-15

    This study describes pentachlophenol (PCP) sorption in nylon fiber in which Rhizopus oryzae ENHE was immobilized to remove the chemical compound. The experimental sorption data were analyzed using the Langmuir, Freundlich, and Redlich-Peterson isotherm models using non-linear error functions to fit the experimental data to the three models. Results showed that the isotherm obtained from the data fitted the three models used. However, the g parameter from Redlich-Peterson model showed that the isotherm obtained approaches the Freundlich model. This support reached the sorption equilibrium concentration at 3mg PCPg(-1)nylon. To study PCP removal capability by R. oryzae ENHE and to eliminate the error caused by PCP sorbed by the nylon fiber during its quantification, nylon fiber at PCP equilibrium sorption concentration was used to immobilize R. oryzae ENHE. It was found that this fungus grew within nylon fiber cubes in presence or not of PCP, even when PCP caused growth inhibition. Maximum biomass accumulated into nylon cubes without PCP was of 32 mg biomass g(-1)nylon and into nylon cubes at PCP equilibrium concentration was of 18 mg g(-1)nylon. The results showed that R. oryzae ENHE immobilized into nylon fiber removed 88.6% and 92% of PCP in cultures with 12.5 and 25 mg PCPL(-1), as initial concentration, respectively. This is the first work to report that a zygomycete, such as R. oryzae ENHE, immobilized into nylon fiber kept its potential to remove PCP.

  6. Sorption of Pyrene by Clay Minerals Coated with Dissolved Organic Matter (DOM from Landfill Leachate

    Directory of Open Access Journals (Sweden)

    Pingxiao Wu

    2015-01-01

    Full Text Available Interactions of dissolved organic matter (DOM from landfill leachate with clays could affect significantly the fate of hydrophobic organic compounds (HOCs in soils. The complexes of montmorillonite (MT and kaolinite (KL with DOM extracted from landfill leachate were prepared under controlled conditions, termed CMT and CKL, respectively. The bare clays and their complexes were characterized by powder X-ray diffraction (XRD, Fourier transform infrared (FTIR, thermogravimetry (TG, differential scanning calorimetry (DSC, and scanning electron microscopy (SEM. Batch experiments were designed to investigate the sorption behavior of pyrene onto the clays in the presence of DOM. The maximum sorption capacities of pyrene on MT, CMT, KL, and CKL were 22.18, 38.96, 42.00, and 44.99 μg·g−1, respectively, at the initial concentration of 1000 ± 150 μg·L−1. The sorption isotherms of pyrene by the bare clays followed the Henry model well, whereas the Freundlich sorption isotherm provided a better fit to the equilibrium data of the sorption by the complexes. The role of montmorillonite and kaolinite complexes with DOM in the retention of pyrene in soils was different. This may be due to the different crystal structures between montmorillonite and kaolinite.

  7. Sorption of selected veterinary antibiotics onto dairy farming soils of contrasting nature.

    Science.gov (United States)

    Srinivasan, Prakash; Sarmah, Ajit K; Manley-Harris, Merilyn

    2014-02-15

    The sorption potential for three sulfonamides (SAs), sulfamethoxazole (SMO), sulfachloropyridazine (SCP) and sulfamethazine (SM) and a macrolide, tylosin tartrate (TT) was assessed on six New Zealand dairy farming soils of contrasting physico-chemical properties. Kinetics studies showed that the sorption was rapid in the first few hours of the contact time (0-2h for SA and 0-4h for TT) and thereafter apparent equilibrium was achieved. Batch sorption isotherm data revealed that the degree of isotherm linearity (N) for SCP and SM varied between 0.50 and 1.08 in the six soils. Isotherms of both TT and SMO were mostly non-linear with the degree of non-linearity for TT (N=0.38-0.71) being greater than for SMO (0.42-0.75) in all soils except Manawatu (TT) and Te Kowhai (SMO) where a linear pattern was observed. Concentration-dependent effective distribution coefficient (Kd(eff)) values for the SMO, SCP and SM antibiotics in the soils ranged from 0.85 to 16.35 L kg(-1), while that for TT was 1.6 to 1,042 L kg(-1). The sorption affinity for all soils followed an order: TT>SCP>SM>SMO. Remarkable high sorption for tylosin in Matawhero soil as compared to other soils was attributed to the presence of oxygen containing acidic polar functional groups as evident in the FT-IR spectra of the soil. Furthermore, it was hypothesised that sorption of TT onto soils was mostly driven by metal oxide-surface mediated transformations whereas for sulfonamides it was primarily due to hydrophobic interactions.

  8. Experimental studies of Cs, Sr, Ni, and Eu sorption on Na-illite and the modelling of Cs sorption

    Energy Technology Data Exchange (ETDEWEB)

    Poinssot, C.; Baeyens, B.; Bradbury, M.H.

    1999-08-01

    A natural illite (illite du Puy) was purified and converted to the homo-ionic Na-form. The conditioned Na-illite was characterised in terms of its mineralogy, chemical inventory and physico-chemical properties. The structural formula was determined from energy dispersive spectroscopic analyses (SEM/TEM-EDS) and bulk chemistry measurements. A cation exchange capacity of 127 meq kg{sup -1} was determined by the {sup 22}Na isotope dilution method at neutral pH. The Na-CEC was also measured as a function of pH. The stability of Na-illite as a function of pH in the range between 3 and 6 was investigated. At low pH values partial dissolution of the illite occurs releasing the structural elements Al, Si, Mg, and K into solution. The presence of Ca and Sr in solution was interpreted as being due to desorption from cation exchange sites. All of these elements are also present at neutral pH but at considerably lower levels. Such effects cannot be avoided and must be considered in the interpretation of the sorption measurements. The main focus of the experimental work presented here is on the sorption behaviour of Cs, Sr, Ni and Eu on conditioned Na-illite as a function of NaClO{sub 4} background electrolyte concentration (0.1 and 0.01 M), nuclide concentration and pH in the range between 3 and 11. Sorption edge data (R{sub d} versus pH) and sorption isotherms (quantity of nuclide sorbed versus equilibrium nuclide concentration) are presented for these four elements. Prior to beginning these experiments, sorption kinetics were measured. The broad based pool of sorption measurements generated from this work will provide the source data sets for subsequent modelling. So far only the Cs sorption measurements have been modelled. A two site cation exchange model was developed to describe the sorption of Cs over the whole range of experimental conditions. The two site types were termed 'frayed edge sites' (FES, high affinity/low capacity) and 'type II sites

  9. Sorption Behaviours of Exfoliated Graphite

    Institute of Scientific and Technical Information of China (English)

    戴光泽; 伍川辉

    2002-01-01

    Exfoliated graphite (EG) is selected as a new kind of sorbent to sorb heavy oil spilled. In order to make use of EG more effectively, some basic experiments are performed to investigate its sorption properties,i.e., specific sorption, height of saturation layer, sorption time constant. In the present experiments, A-grade heavy oil is employed as a standard sorbate. It is concluded that 1) under the condition that the area of solid (filter bottom)-liquid (heavy oil) interface is a constant, specific sorption usually decreases when the amount of EG filled or the apparent bulk density increase; however, the specific sorption initially increases when the apparent bulk density is too low and the amount of EG filled is too much; 2) under the condition that the apparent bulk density of EG filled is a constant, the sorption time constant tends to increase when the amount of EG filled increases; however, for a constant amount of EG filled, the sorption time constant will decrease when the apparent bulk density increases.

  10. Sorption of Pesticides to Natural and Synthetic Nanoparticles

    Science.gov (United States)

    Guluzada, Leyla; Luo, Leilei; Pattky, Martin; Anwander, Reiner; Huhn, Carolin; Haderlein, Stefan

    2017-04-01

    Many organic pollutants tend to associate with particles in environment. Such interactions with solid surfaces may not only alter the reactivity and bioavailability of pesticides, but also their uptake. This alteration may occur both in the way and in the amount the compound enters the organisms. In its turn this may change the overall effects of these compounds on organisms and ecosystems. The main goal of the work presented here is to provide mechanistic information on the sorbate-sorbent interactions between nanoparticles and a set of pesticides under environmentally relevant and physiological conditions. As such, the work is part of the interdisciplinary graduate research program EXPAND at the University of Tübingen investigating molecular interactions between pesticides and particles to elucidate how such interactions impact the toxicological effects. To this end, natural and synthetic nanoparticles covering a wide range of physicochemical properties and pesticides for different target organisms were used. Sorption experiments were carried out with insecticides (imidacloprid; thiacloprid), fungicides (hexaconazole; propiconazole) and herbicides (glyphosate with its metabolite AMPA; glufosinate). The choice of the pesticides was based on their environmental significance and their mode of action. Both engineered nanoparticles with tailored surface properties and nanoparticles of natural origin were characterized and applied to cover various modes of sorptive interactions with the pesticides. The impact of various geochemical and physiological conditions including pH, temperature, ionic strength, background electrolytes and DOM (dissolved organic matter) on the sorption of the pesticides to nanoparticles was studied. Sorption kinetics and sorption isotherms were determined and the results are discussed in terms of predominant sorption mechanisms and the suitability of certain nanoparticles for toxicological studies in the framework of the EXPAND project.

  11. Sorption study of U{sup +6} in Brazilian soils

    Energy Technology Data Exchange (ETDEWEB)

    Junior, Antonio P.; Wasserman, Maria A.V.; Mantovano, Jose L.; Carvalho, Leonel M., E-mail: apjunior@ien.gov.br, E-mail: mwasserman@ien.gov.br, E-mail: mantovan@ien.gov.br, E-mail: leonel@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Perez, Daniel V., E-mail: daniel@cnps.embrapa.br [Empresa Brasileira de Pesquisas Agropecuarias (Embrapa Solos-CNPS), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    The uranium mining is one of the main activities of the nuclear fuel cycle that can contribute to the increased exposure to radioactive materials and is one of the main routes of contamination of soil by natural radionuclides. This study investigated the sorption of uranium in brazilian soils, through sorption isotherms performed in batch. In this study, two types of soils were selected: Ferralsols Red and Nitosol. The adjustment of the experimental data to the kinetic models were evaluated by two approaches: the traditional, based on the coefficient of determination (R{sup 2}); and the theoretical and informative, based on Corrected Akaike Information Criteria (AIC{sub C}). The coefficient of determination (R{sup 2}), revealed that, although empirical, both the kinetic model, Freundlich and Langmuir, describes satisfactorily the experimental data, showing R{sup 2} values higher than 0.9, while the partition constant model was not suitable for describe these sorption data. The AICC model analysis showed that the Langmuir model fit the U sorption curve well for Ferralsols Red, while the Freundlich model fits better to Nitosol. This study has highlighted the role of organic matter on the sorption of uranium in highly weathered soils, rich in oxyhydroxides and low activity clays. The Kd values reported in this study differ from those recommended by the United States Environmental Protection Agency, therefore must be considered as reference values for highly weathered soils, since it refers to Brazilian pedoenvironmental conditions. The low Kd values obtained in this study allowed to evaluate the high vulnerability of highly weathered soils to uranium contamination. (author)

  12. Abamectin in soils: Analytical methods, kinetics, sorption and dissipation.

    Science.gov (United States)

    Dionisio, Andreza Camilotti; Rath, Susanne

    2016-05-01

    Abamectin is a broad-spectrum antiparasitic agent that has been widely employed in veterinary medicine and has also been used as a pesticide in agriculture. Veterinary drugs may reach the soil and may be transported to surface and ground waters, posing risks to terrestrial and aquatic organisms. Sorption, transformation and transport processes are primarily responsible for the fate of these substances in the environment. In this study, the sorption and the aerobic dissipation of abamectin in Brazilian soils (sand, clay and sandy-clay) were evaluated. For sorption studies, batch equilibrium experiments were performed. Sorption and desorption isotherms were fitted to the Freundlich model. Abamectin showed a high affinity to soil particles, with Freundlich sorption and desorption coefficients ranging from 44 to 138 μg(1-1/n) (cm(3))(1/n) g(-1) and from 89 to 236 μg(1-1/n) (cm(3))(1/n) g(-1), respectively. Dissipation of abamectin was evaluated in sterile and non-sterile soils in an aerobic and dark environment under controlled temperature and humidity. The time required for a 50% reduction of the amount of abamectin present in non-sterile soils was up to 4 days, and the time period for 90% dissipation was up to 12 days. In sterilized soils, there was no reduction in the concentration of abamectin over 37 days of exposure, suggesting that aerobic microbial degradation must have been the primary mechanism responsible for the dissipation of abamectin in soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. SORPTION BEHAVIOR OF MONOSODIUM TITANATE AND AMORPHOUS PEROXOTITANATE MATERIALS UNDER WEAKLY ACIDIC CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.; Elvington, M.; Click, D.

    2009-11-11

    Inorganic, titanate-based sorbents are tested with respect to adsorption of a variety of sorbates under weakly acidic conditions (pH 3). Specifically, monosodium titanate (MST) and amorphous peroxotitanate (APT) sorption characteristics are initially probed through a screening process consisting of a pair of mixed metal solutions containing a total of 29 sorbates including alkali metals, alkaline earth metals, transition metals, metalloids and nonmetals. MST and APT sorption characteristics are further analyzed individually with chromium(III) and cadmium(II) using a batch method at ambient laboratory temperature, varying concentrations of the sorbents and sorbates and contact times. Maximum sorbate loadings are obtained from the respective adsorption isotherms.

  14. Sorption and degradation of selected pharmaceuticals in representative soils of the Czech Republic

    Science.gov (United States)

    Kodesova, Radka; Kocarek, Martin; Klement, Ales; Golovko, Oksana; Grabic, Roman; Fer, Miroslav; Nikodem, Antonin; Jaksik, Ondrej

    2015-04-01

    Knowledge of contaminant behavior (e.g. its sorption onto soil particle, degradation etc.) is essential when assessing contaminant migration in soil and groundwater environment. This study was focused on evaluating sorption isotherms and half-lives for 7 pharmaceuticals (clarithromycin, trimethoprim, metoprolol, atenolol, clindamycin, carbamazepine, sulfamethoxazole) on 13 soils of different soil properties. Sorption of ionizable compounds was highly affected by soil pH. The sorption coefficient of sulfamethoxazole was negatively correlated to soil pH and thus positively related to hydrolytic acidity and exchangeable acidity. Sorption coefficients for clindamycin and clarithromycin were positively related to soil pH and thus negatively related to hydrolytic acidity and exchangeable acidity and positively related to base cation saturation. Sorption coefficients for the remaining pharmaceuticals (trimethoprim, metoprolol, atenolol, and carbamazepine) were also positively correlated with the base cation saturation and cation exchange capacity. Degradation rates in some degree reflected sorption of studied pharmaceuticals on soil particles and increased with decreasing sorption. The highest mobility in studied soils was observed for sulfamethoxazole, but this pharmaceutical was relatively quickly degraded. The second highest mobility was found for carbamazepine, which mostly did not noticeably degrade during our experiments. Thus this pharmaceutical has the highest potential to migrate in water environment. The lowest mobility was observed for clarithromycin. However, this pharmaceutical due to its stability may be retained in an environment for a long time. Acknowledgement: The authors acknowledge the financial support of the Czech Science Foundation (Project No. 13-12477S, Transport of pharmaceuticals in soils). References: Kodesova, R., Grabic, R., Kocarek, M., Klement, A., Golovko, O., Fer, M., Nikodem, A., Jaksik, O., Pharmaceuticals' sorptions relative to

  15. Sorption and transformation of the reactive tracers resazurin and resorufin in natural river sediments

    Science.gov (United States)

    Lemke, D.; González-Pinzón, R.; Liao, Z.; Wöhling, T.; Osenbrück, K.; Haggerty, R.; Cirpka, O. A.

    2014-08-01

    Resazurin (Raz) and its reaction product resorufin (Rru) have increasingly been used as reactive tracers to quantify metabolic activity and hyporheic exchange in streams. Previous work has indicated that these compounds undergo sorption in stream sediments. We present laboratory experiments on Raz and Rru transport, sorption, and transformation, consisting of 4 column and 72 batch tests using 2 sediments with different physicochemical properties under neutral (pH = 7) and alkaline (pH = 9) conditions. The study aimed at identifying the key processes of reactive transport of Raz and Rru in streambed sediments and the experimental setup best suited for their determination. Data from column experiments were simulated by a travel-time-based model accounting for physical transport, equilibrium and kinetic sorption, and three first-order reactions. We derived the travel-time distributions directly from the breakthrough curve (BTC) of the conservative tracer, fluorescein, rather than from fitting an advective-dispersive transport model, and inferred from those distributions the transfer functions of Raz and Rru, which provided conclusive approximations of the measured BTCs. The most likely reactive transport parameters and their uncertainty were determined by a Markov chain-Monte Carlo approach. Sorption isotherms of both compounds were obtained from batch experiments. We found that kinetic sorption dominates sorption of both Raz and Rru, with characteristic timescales of sorption in the order of 12 to 298 min. Linear sorption models for both Raz and Rru appeared adequate for concentrations that are typically applied in field tracer tests. The proposed two-site sorption model helps to interpret transient tracer tests using the Raz-Rru system.

  16. Ammonia-nitrogen and phosphates sorption from simulated reclaimed waters by modified clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Hanxin [School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of the Ministry of Education of China for High-Efficient Mining and Safety of Metal Mines, Beijing 100083 (China); Lin, Hai, E-mail: linhai@ces.ustb.edu.cn [School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of the Ministry of Education of China for High-Efficient Mining and Safety of Metal Mines, Beijing 100083 (China); Dong, Yingbo; Cheng, Huang; Wang, Han; Cao, Lixia [School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of the Ministry of Education of China for High-Efficient Mining and Safety of Metal Mines, Beijing 100083 (China)

    2012-08-30

    Highlights: Black-Right-Pointing-Pointer The salt and thermally modified clinoptilolite can effectively sorb NH{sub 3}-N and phosphates. Black-Right-Pointing-Pointer The phosphorus and nitrogen removal was consistent with Langmuir isotherm model. Black-Right-Pointing-Pointer The modified clinoptilolite possesses rapid adsorption and slow balance characteristics. Black-Right-Pointing-Pointer The adsorption is more in line with the Elovich adsorption dynamics equation. Black-Right-Pointing-Pointer The entropy effect plays the role of the main driving force in the adsorption. - Abstract: This paper presents the investigation of the ammonia-nitrogen and phosphates sorption from simulated reclaimed wastewater by modified clinoptilolite. The results showed that the modified clinoptilolite has a high sorption efficiency and removal performance. The ammonia-nitrogen and phosphates removal rate of the modified clinoptilolite reached to 98.46% and 99.80%, respectively. The surface of modified clinoptilolite became loose and some pores appeared, which enlarged the specific surface area; the contents of Na and Fe increased, and the contents of Ca and Mg decreased. The modified clinoptilolite possesses rapid sorption and slow balance characteristics and ammonia-nitrogen and phosphates sorption is more consistent with the Langmuir isotherm model. The adsorption kinetics of ammonia-nitrogen and phosphates follows the Elovich adsorption dynamics equation, which describes the sorption of ammonia-nitrogen and phosphates in aqueous solution as mainly a chemical sorption. Results from the thermodynamics experiment involving ammonia-nitrogen and phosphates sorption reveal that the process is a spontaneous and endothermic process, and is mainly driven by entropy effect.

  17. Thermodynamics of cadmium sorption on different soils of West Bengal, India.

    Science.gov (United States)

    Karak, Tanmoy; Paul, Ranjit Kumar; Das, D K; Boruah, Romesh K; Sonar, Indira

    2014-01-01

    A sorption study was conducted on different soils collected from five agroecological zones of West Bengal, India, to understand the soil environmental behavior and fate of cadmium. For this purpose batch adsorption experiments were carried out at the native soil pH and at three different temperatures (25°C, 35°C, and 45°C). The adsorption data fitted by a linear least squares technique to the different sorption isotherms. Most data obtained give the good fit to both Freundlich and modified Langmuir isotherms, but they are not consistent with the linear Langmuir adsorption model. Thermodynamic parameters, namely, thermodynamics equilibrium constant at a particular temperature T (K T (0)), Gibbs free energy at a particular temperature T (ΔG T (0)), and change of enthalpy (ΔH (0)) and change of entropy at temperature T (ΔS T (0)), were also determined by applying sorption value and concentrations of Cd in equilibrium solution within the temperature range. The thermodynamic parameters revealed that Cd sorption increases as the values of K T (0), ΔG T (0), ΔH (0), and ΔS T (0) were increased on reaction temperatures. The spontaneous sorption reaction can be concluded due to high values of ΔG T (0). The positive values of ΔH (0) indicated that the Cd sorption is an endothermic one. Under these present conditions, the soil and its components possibly supply a number of sites having different adsorption energies for cadmium sorption.

  18. Thermodynamics of Cadmium Sorption on Different Soils of West Bengal, India

    Directory of Open Access Journals (Sweden)

    Tanmoy Karak

    2014-01-01

    Full Text Available A sorption study was conducted on different soils collected from five agroecological zones of West Bengal, India, to understand the soil environmental behavior and fate of cadmium. For this purpose batch adsorption experiments were carried out at the native soil pH and at three different temperatures (25°C, 35°C, and 45°C. The adsorption data fitted by a linear least squares technique to the different sorption isotherms. Most data obtained give the good fit to both Freundlich and modified Langmuir isotherms, but they are not consistent with the linear Langmuir adsorption model. Thermodynamic parameters, namely, thermodynamics equilibrium constant at a particular temperature T  (KT0, Gibbs free energy at a particular temperature T  (ΔGT0, and change of enthalpy (ΔH0 and change of entropy at temperature T  (ΔST0, were also determined by applying sorption value and concentrations of Cd in equilibrium solution within the temperature range. The thermodynamic parameters revealed that Cd sorption increases as the values of KT0, ΔGT0, ΔH0, and ΔST0 were increased on reaction temperatures. The spontaneous sorption reaction can be concluded due to high values of ΔGT0. The positive values of ΔH0 indicated that the Cd sorption is an endothermic one. Under these present conditions, the soil and its components possibly supply a number of sites having different adsorption energies for cadmium sorption.

  19. FORMULASI TEPUNG PENYALUT BERBASIS TEPUNG JAGUNG DAN PENENTUAN UMUR SIMPANNYA DENGAN PENDEKATAN KADAR AIR KRITIS [Formulation of Corn Flour-Based Batter and Prediction of Its Shelf Life using Critical Moisture Approach

    Directory of Open Access Journals (Sweden)

    Sugiyono1*

    2010-12-01

    Full Text Available The objectives of this study were to obtain the best formula for corn flour-based batter and to predict its shelf life using critical moisture approach. According to a hedonic test, the best batter formula was composed of 60% corn flour, 12.5% rice flour, 12.5% tapioca starch, and 15% glutinous rice flour. Addition of glutinous rice flour in the formula changed the proportion of amylose and amylopectin in the batter. As a result, the retrogradation of the batter decreased and the texture of its fried product was preferred. A critical moisture approach was used to predict the shelf life of the batter. The critical moisture content of the batter was 0.16 g H2O/g solid.The isotherm sorption phenomenon of the batter was best described using Hasley model. The shelf life of the product was 7 months when packaged in polypropylene (0,07 g/m2day.mmHg at 85% RH.

  20. Effects of humidity and soil organic matter on the sorption of chlorinated methanes in synthetic humic-clay complexes.

    Science.gov (United States)

    Canan Cabbar, H

    1999-09-10

    Vapor-phase sorption is the most influential process governing the transport and the fate of volatile organic compounds in soil. To understand the influence of both soil organic content and the humidity of soil on the vapor sorption is an important process for degradation processes. The single-pellet moment technique was used to investigate sorption and diffusion of trichloromethane (TCM) and carbon tetrachloride (CTC) at varying relative humidities (0-80%) of synthetic humic-clay complex pellets consisting of clay (montmorillonite) and different amounts of organic matter (humic acid). The effective diffusivities of TCM and CTC did not show a noticeable change with moisture and humic acid content. On the other hand, with increasing humic acid content of clay at 0% relative humidity, an appreciable decrease of the equilibrium sorption constants of the tracers (TCM, CTC) was found because of the blockage of some sites of the mineral surfaces and especially micropores by the humic acid. The presence of water also reduced dramatically the sorption of TCM and CTC on synthetic humic-clay complexes. Above 20% relative humidity, the sorption coefficient of TCM and CTC varied only slightly with humic acid content. It was concluded that the sorption of TCM and CTC in synthetic humic-clay complexes was strongly effected by the moisture and humic acid content.

  1. Sorption-desorption of fipronil in some soils, as influenced by ionic strength, pH and temperature.

    Science.gov (United States)

    Singh, Anand; Srivastava, Anjana; Srivastava, Prakash C

    2016-08-01

    The sorption-desorpion of fipronil insecticide is influenced by soil properties and variables such as pH, ionic strength, temperature, etc. A better understanding of soil properties and these variables in sorption-desorption processes by quantification of fipronil using liquid chromatography may help to optimise suitable soil management to reduce contamination of surface and groundwaters. In the present investigation, the sorption-desorption of fipronil was studied in some soils at varying concentrations, ionic strengths, temperatures and pH values, and IR specta of fipronil sorbed onto soils were studied. The sorption of fipronil onto soils conformed to the Freundlich isotherm model. The sorption-desorption of fipronil varied with ionic strength in each of the soils. Sorption decreased but desorption increased with temperature. Sorption did not change with increasing pH, but for desorption there was no correlation. The cumulative desorption of fipronil from soil was significantly and inversely related to soil organic carbon content. IR spectra of sorbed fipronil showed the involvement of amino, nitrile, sulfone, chloro and fluoro groups and the pyrazole nucleus of the fipronil molecule. The sorption of fipronil onto soils appeared to be a physical process with the involvement of hydrogen bonding. An increase in soil organic carbon may help to reduce desorption of fipronil. High-temperature regimes are more conducive to the desorption. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  2. Arsenic(III) sorption on nanostructured cerium incorporated manganese oxide (NCMO): a physical insight into the mechanistic pathway

    CSIR Research Space (South Africa)

    Gupta, K

    2012-07-01

    Full Text Available ° = +0.14 kJ mol-1 K-1) at solid–liquid interface. Energy of arsenic(III) sorption estimated by analyzing the equilibrium data using the D–R isotherm model was 15.4 kJ mol-1, indicating the ion-exchange type mechanism. Raman, FT-IR, pH effect, desorption...

  3. Sorption of organic cations to phyllosilicate clay minerals: CEC-normalization, salt dependency, and the role of electrostatic and hydrophobic effects.

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    Sorption to the phyllosilicate clay minerals Illite, kaolinite, and bentonite has been studied for a wide variety of organic cations using a flow-through method with fully aqueous medium as the eluent. Linear isotherms were observed at concentrations below 10% of the cation-exchange capacity (CEC) for Illite and kaolinite and below 1 mmol/kg (<1% CEC) for bentonite. Sorption to clays was strongly influenced by the electrolyte composition of the eluent but with a consistent trend for a diverse set of compounds on all clays, thus allowing for empirical correction factors. When sorption affinities for a given compound to a given clay are normalized to the CEC of the clay, the differences in sorption affinities between clays are reduced to less than 0.5 log units for most compounds. Although CEC-normalized sorption of quaternary ammonium compounds to clay was up to 10-fold higher than CEC-normalized sorption to soil organic matter, CEC-normalized sorption for most compounds was comparable between clays and soil organic matter. The clay fraction is thus a potentially relevant sorption phase for organic cations in many soils. The sorption data for organic cations to clay showed several regular trends with molecular structure but also showed quite a few systematic effects that we cannot explain. A model on the basis of the molecular size and charge density at the ionized nitrogen is used here as a tool to obtain benchmark values that elucidate the effect of specific polar moieties on the sorption affinity.

  4. Isothermal Amplification of Nucleic Acids.

    Science.gov (United States)

    Zhao, Yongxi; Chen, Feng; Li, Qian; Wang, Lihua; Fan, Chunhai

    2015-11-25

    Isothermal amplification of nucleic acids is a simple process that rapidly and efficiently accumulates nucleic acid sequences at constant temperature. Since the early 1990s, various isothermal amplification techniques have been developed as alternatives to polymerase chain reaction (PCR). These isothermal amplification methods have been used for biosensing targets such as DNA, RNA, cells, proteins, small molecules, and ions. The applications of these techniques for in situ or intracellular bioimaging and sequencing have been amply demonstrated. Amplicons produced by isothermal amplification methods have also been utilized to construct versatile nucleic acid nanomaterials for promising applications in biomedicine, bioimaging, and biosensing. The integration of isothermal amplification into microsystems or portable devices improves nucleic acid-based on-site assays and confers high sensitivity. Single-cell and single-molecule analyses have also been implemented based on integrated microfluidic systems. In this review, we provide a comprehensive overview of the isothermal amplification of nucleic acids encompassing work published in the past two decades. First, different isothermal amplification techniques are classified into three types based on reaction kinetics. Then, we summarize the applications of isothermal amplification in bioanalysis, diagnostics, nanotechnology, materials science, and device integration. Finally, several challenges and perspectives in the field are discussed.

  5. Influence of molecular structure and adsorbent properties on sorption of organic compounds to a temperature series of wood chars.

    Science.gov (United States)

    Lattao, Charisma; Cao, Xiaoyan; Mao, Jingdong; Schmidt-Rohr, Klaus; Pignatello, Joseph J

    2014-05-01

    Chars from wildfires and soil amendments (biochars) are strong adsorbents that can impact the fate of organic compounds in soil, yet the effects of solute and adsorbent properties on sorption are poorly understood. We studied sorption of benzene, naphthalene, and 1,4-dinitrobenzene from water to a series of wood chars made anaerobically at different heat treatment temperatures (HTT) from 300 to 700 °C, and to graphite as a nonporous, unfunctionalized reference adsorbent. Peak suppression in the NMR spectrum by sorption of the paramagnetic relaxation probe TEMPO indicated that only a small fraction of char C atoms lie near sorption sites. Sorption intensity for all solutes maximized with the 500 °C char, but failed to trend regularly with N2 or CO2 surface area, micropore volume, mesopore volume, H/C ratio, O/C ratio, aromatic fused ring size, or HTT. A model relating sorption intensity to a weighted sum of microporosity and mesoporosity was more successful. Sorption isotherm linearity declined progressively with carbonization of the char. Application of a thermodynamic model incorporating solvent-water and char-graphite partition coefficients permitted for the first time quantification of steric (size exclusion in pores) and π-π electron donor-acceptor (EDA) free energy contributions, relative to benzene. Steric hindrance for naphthalene increases exponentially from 9 to 16 kJ/mol (∼ 1.6-2.9 log units of sorption coefficient) with the fraction of porosity in small micropores. π-π EDA interactions of dinitrobenzene contribute -17 to -19 kJ/mol (3-3.4 log units of sorption coefficient) to sorption on graphite, but less on chars. π-π EDA interaction of naphthalene on graphite is small (-2 to 2 kJ/mol). The results show that sorption is a complex function of char properties and solute molecular structure, and not very predictable on the basis of readily determined char properties.

  6. Phosphate Sorption Characteristics and External P Requirements of Selected South African Soils

    Directory of Open Access Journals (Sweden)

    E. M. Gichangi

    2008-10-01

    Full Text Available The Transkei is the largest consolidated area in South Africa where land is held by smallholder farmers but little is known about the extent of phosphate fixation in the region. This study was conducted to determine the phosphate sorption properties and external P requirements (EPR of selected soils from the Transkei region, South Africa and to relate derived sorption values to selected soil parameters. The P sorption maxima and EPR values varied widely ranging from 192.3 to 909.1 mg P kg−1 and from 2 to 123 mg P kg−1−1 soil, respectively. Citrate dithionite bicarbonate-extractable aluminum explained most of the observed variations in P sorption. About 43% of the soils were found to be moderate P fixers and may need management interventions to ensure adequate P availability to crops. The single point sorption index accurately predicted the EPR of the soils obviating the need to use multiple point sorption isotherms. The results suggested that the use of blanket phosphate fertilizer recommendations may not be a good strategy for the region as it may lead to under-application or over-application of P in some areas.

  7. Sorption and biodegradation characteristics of the selected pharmaceuticals and personal care products onto tropical soil.

    Science.gov (United States)

    Foolad, Mahsa; Hu, Jiangyong; Tran, Ngoc Han; Ong, Say Leong

    2016-01-01

    In the present study, the sorption and biodegradation characteristics of five pharmaceutical and personal care products (PPCPs), including acetaminophen (ACT), carbamazepine (CBZ), crotamiton (CTMT), diethyltoluamide (DEET) and salicylic acid (SA), were studied in laboratory-batch experiments. Sorption kinetics experimental data showed that sorption systems under this study were more appropriately described by the pseudo second-order kinetics with a correlation coefficient (R2)>0.98. Sorption equilibrium data of almost all target compounds onto soil could be better described by the Freundlich sorption isotherm model. The adsorption results showed higher soil affinity for SA, following by ACT. Results also indicated a slight effect of pH on PPCP adsorption with lower pH causing lower adsorption of compounds onto the soil except for SA at pH 12. Moreover, adsorption of PPCPs onto the soil was influenced by natural organic matter (NOM) since the higher amount of NOM caused lower adsorption to the soil. Biodegradation studies of selected PPCPs by indigenous microbial community present in soil appeared that the removal rates of ACT, SA and DEET increased with time while no effect had been observed for the rest. This study suggests that the CBZ and CTMT can be considered as suitable chemical sewage indicators based on their low sorption affinity and high resistance to biodegradation.

  8. [Effects of soil compositions on sorption and desorption behavior of tetrachloroethylene in soil].

    Science.gov (United States)

    Hu, Lin; Qiu, Zhao-Fu; He, Long; Dou, Ying; Lü, Shu-Guang; Sui, Qian; Lin, Kuang-Fei

    2013-12-01

    Sorption and desorption play an important role in the transport and the fate of tetrachloroethylene (PCE) in soil. In order to examine influences of different soil compositions on PCE sorption-desorption, equilibrium batch experiments were carried out using four sorbents (natural soil with 2.23% total organic carbon (TOC), H2O2-treated soil, 375 degrees C-treated soil and 600 degrees C-treated soil) with different initial PCE liquid concentrations (c0). The effects of main parameters (TOC, soft carbon, hard carbon, minerals, c0) on PCE sorption-desorption were investigated. At 16 degrees C, when c0 was increased from 5 to 80 mg x L(-1), the results showed that sorption and desorption isotherms of PCE on four sorbents can be best described by the Freundlich model (r2 > 0.96). The sorption contribution rate of SOM was higher than 60% in natural soil, and hard carbon was the main influencing factor,while the desorption contribution rate of SOM was close to that of minerals in natural soil, and soft carbon accounted for more than 80% in the total desorption contribution rate of SOM. In addition, the higher the c0, the higher the sorption contribution rate of PCE in hard carbon and desorption contribution rate of PCE in soft carbon and minerals were. Moreover, desorption of PCE from four sorbents exhibited hysteresis, and hard carbon played a remarkable role in the hysteresis of natural soil.

  9. Competitive sorption of persistent organic pollutants onto microplastics in the marine environment.

    Science.gov (United States)

    Bakir, Adil; Rowland, Steven J; Thompson, Richard C

    2012-12-01

    Plastics are known to sorb persistent organic pollutants from seawater. However, studies to quantify sorption rates have only considered the affinity of chemicals in isolation, unlike the conditions in the environment where contaminants are present as complex mixtures. Here we examine whether phenanthrene and 4,4'-DDT, in a mixture, compete for sorption sites onto PVC with no added additives (unplasticised PVC or uPVC) and Ultra-High Molecular Weight polyethylene. Interactions were investigated by exposing particles of uPVC and UHMW PE to mixtures of 3H and 14C radiolabelled Phe and DDT. Changes in sorption capacity were modelled by applying a Freundlich binding sorption isotherms. An Extended Langmuir Model and an Interaction Factor Model were also applied to predict equilibrium concentrations of pollutants onto plastic. This study showed that in a bi-solute system, DDT exhibited no significantly different sorption behaviour than in single solute systems. However, DDT did appear to interfere with the sorption of Phe onto plastic, indicating an antagonistic effect.

  10. Sorption of a triazol derivative by soils: importance of surface acidity

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H2O2-treated soils was investigated. The sorption isotherm for each untreated and treated soil was non-linear, and was best fitted to Freundlich sorption equation. Soils containing high amount of clay content or organic matter or both sorbed much higher amounts of the chemical than soils that had low contents of these soil constituents. H2O2-treated soils showed considerable sorptive affinity for S3307D. It was concluded that both organic matter and mineral fraction in natural soils contributed to the sorption of the basic compound. Sorption by the H2O2 treated soils increased as suspension pH decreased, but all suspension pHs exceeded the pKa of the compound by more than two units. This implies that organic base protonation can occur on surfaces of soil components, and surface acidity (exchangeable acidity ) is important in sorption process of the organic base rather than suspension pH.

  11. Competitive sorption of intermixed heavy metals in water repellent soil in Southern Australia

    Science.gov (United States)

    Li, P. J.; Stagnitti, F.; Xiong, X.; Li, P.

    2007-04-01

    In water repellent soil, Cr, Pb and Cu showed higher adsorption intensities than Zn, Cd and Ni did. Soil water repellency is much more widespread than formerly thought. In order to promote fertility and productivity, the irrigation of recycled water onto water repellent soil may be an applied technology to be used in some areas of Southern Australia. Therefore, heavy metals in recycled water potentially enter into the soil. The competitive sorption and retention capacity of heavy metals in soil are important to be determined, especially considering the special geochemical origin of water repellent soil that was caused by waxes on or between the soil particles. Batch equilibrium sorption experiments on Cd, Cr, Cu, Ni, Pb and Zn in their typical proportion in recycled water were conducted in water repellent soil. The sorption intensity, sorption isotherm in the experiments together showed that Cr, Pb and Cu have higher sorption intensity than those of Zn, Ni and Cd in the competitive system. The risk assessment for the application of recycled water onto water repellent soil is definitely necessary, especially for the metal cations with relatively weak sorption.

  12. Arsenite sorption and co-precipitation with calcite

    CERN Document Server

    Roman-Ross, Gabriela; Turrillas, Xavier; Fernandez-Martinez, Alejandro; Charlet, Laurent

    2008-01-01

    Sorption of As(III) by calcite was investigated as a function of As(III) concentration, time and pH. The sorption isotherm, i.e. the log As(III) vs. log [As(OH)3 degrees / Assat] plot is S-shaped and has been modelled on an extended version of the surface precipitation model. At low concentrations, As(OH)3 degrees is adsorbed by complexation to surface Ca surface sites, as previously described by the X-ray standing wave technique. The inflexion point of the isotherm, where As(OH)3 degrees is limited by the amount of surface sites (ST), yields 6 sites nm-2 in good agreement with crystallographic data. Beyond this value, the amount of sorbed arsenic increases linearly with solution concentration, up to the saturation of arsenic with respect to the precipitation of CaHAsO3(s). The solid solutions formed in this concentration range were examined by X-ray and neutron diffraction. The doped calcite lattice parameters increase with arsenic content while c/a ratio remains constant. Our results made on bulk calcite on...

  13. The effect of changing ambient humidity on moisture condition in timber elements

    DEFF Research Database (Denmark)

    Hozjan, Tomaẑ; Turk, Goran; Srpĉiĉ, Stanislav;

    2012-01-01

    This paper deals with the effect of the changing ambient humidity on moisture conditions in timber elements. The naturally varying humidity is possible to model as a relative combination of different harmonic cycles, with different periods and amplitudes. For the determination of the moisture field...... a fully coupled transport model including a model for the influential sorption hysteresis of wood is used. The coupled model accounts for both vapor transport in pores and bound water transport in wood tissue. Moisture state history influences relationship between moisture state of wood and air humidity...

  14. Investigating the gas sorption mechanism in an rht -metal-organic framework through computational studies

    KAUST Repository

    Pham, Tony T.

    2014-01-09

    Grand canonical Monte Carlo (GCMC) simulations were performed to investigate CO2 and H2 sorption in an rht-metal-organic framework (MOF) that was synthesized with a ligand having a nitrogen-rich trigonal core through trisubstituted triazine groups and amine functional groups. This MOF was synthesized by two different groups, each reporting their own distinct gas sorption measurements and crystal structure. Electronic structure calculations demonstrated that the small differences in the atomic positions between each group\\'s crystal structure resulted in different electrostatic parameters about the Cu2+ ions for the respective unit cells. Simulations of CO2 sorption were performed with and without many-body polarization effects and using our recently developed CO2 potentials, in addition to a well-known bulk CO2 model, in both crystallographic unit cells. Simulated CO2 sorption isotherms and calculated isosteric heats of adsorption, Qst, values were in excellent agreement with the results reported previously by Eddaoudi et al. for both structures using the polarizable CO2 potential. For both crystal structures, the initial site for CO2 sorption were the Cu 2+ ions that had the higher positive charge in the unit cell, although the identity of this electropositive Cu2+ ion was different in each case. Simulations of H2 sorption were performed with three different hydrogen potentials of increasing anisotropy in both crystal structures and the results, especially with the highest fidelity model, agreed well with Eddaoudi et al.\\'s experimental data. The preferred site of H 2 sorption at low loading was between two Cu2+ ions of neighboring paddlewheels. The calculation of the normalized hydrogen dipole distribution for the polarizable model in both crystal structures aided in the identification of four distinct sorption sites in the MOF, which is consistent to what was observed in the experimental inelastic neutron scattering (INS) spectra. Lastly, while the

  15. Sorption behavior of U(VI) on phyllite: experiments and modeling

    Science.gov (United States)

    Arnold, Thuro; Zorn, T.; Zänker, H.; Bernhard, G.; Nitsche, H.

    2001-02-01

    The sorption of U(VI) onto low-grade metamorphic rock phyllite was modeled with the diffuse double layer model (DDLM) using the primary mineralogical constituents of phyllite, i.e. quartz, chlorite, muscovite, and albite, as input components, and as additional component, the poorly ordered Fe oxide hydroxide mineral, ferrihydrite. Ferrihydrite forms during the batch sorption experiment as a weathering product of chlorite. In this process, Fe(II), leached from the chlorite, oxidizes to Fe(III), hydrolyses and precipitates as ferrihydrite. The formation of ferrihydrite during the batch sorption experiment was identified by Mössbauer spectroscopy, showing a 2.8% increase of Fe(III) in the phyllite powder. The ferrihydrite was present as Fe nanoparticles or agglomerates with diameters ranging from 6 to 25 nm, with indications for even smaller particles. These Fe colloids were detected in centrifugation experiments of a ground phyllite suspension using various centrifugal forces. The basis for the successful interpretation of the experimental sorption data of uranyl(VI) on phyllite were: (1) the determination of surface complex formation constants of uranyl with quartz, chlorite, muscovite, albite, and ferrihydrite in individual batch sorption experiments, (2) the determination of surface acidity constants of quartz, chlorite, muscovite, and albite obtained from separate acid-base titration, (3) the determination of surface site densities of quartz, chlorite, muscovite, and albite evaluated independently of each other with adsorption isotherms, and (4) the quantification of the secondary phase ferrihydrite, which formed during the batch sorption experiments with phyllite. The surface complex formation constants and the protolysis constants were optimized by using the experimentally obtained data sets and the computer code FITEQL. Surface site densities were evaluated from adsorption isotherms at pH 6.5. The uranyl(VI) sorption onto phyllite was accurately modeled with

  16. Characterization of U(VI) Sorption-Desorption Processes and Model Upscaling

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Jing; Dong, Wenming; Ball, William P.

    2006-10-12

    (VI) diffusion in silt/clay layers. Batch isotherm experiments were first used to confirm sorption isotherms under the intended test conditions and diffusion cell experiments were then conducted to explore the diffusion hypotheses. Important new information was obtained about the role of aqueous calcium and solid calcium carbonate in controlling sorption equilibrium with Hanford sediments. The retarded interparticle diffusion model with local sorption equilibrium was shown to very successfully simulate diffusion at high aqueous concentration of U(VI). By contrast, however, diffusion data obtained at low concentration suggested nonequilibrium of sorption even at diffusion time scales. Such nonequilibrium effects at low concentration are likely to be the result of sorption retarded intraparticle diffusion, and strong U(VI) sorption in the low concentration range.

  17. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  18. Hydrogen sorption in Pd monolayers in alkaline solution

    Energy Technology Data Exchange (ETDEWEB)

    Martin, M.H. [Departement de chimie, Universite de Sherbrooke, 2500 blvd. de l' Universite, Sherbrooke, Quebec, J1K 2R1 (Canada); Lasia, A. [Departement de chimie, Universite de Sherbrooke, 2500 blvd. de l' Universite, Sherbrooke, Quebec, J1K 2R1 (Canada)], E-mail: a.lasia@usherbrooke.ca

    2009-09-01

    Hydrogen adsorption/absorption at palladium monolayers (ML) deposited on monocrystalline Au(1 1 1) electrode was studied in 0.1 M NaOH solution. H charge isotherms demonstrated that adsorption started at potentials more positive than at thicker nanometric Pd/Au(polycrystal) deposits. Due to 3-dimensional deposit growth, absorption could be seen at all deposits thicker than 1 ML. Besides, H sorption at Pd/Au(1 1 1) monolayers was more reversible than at nanometric Pd/Au(polycrystal) deposits. Strong geometric and electronic effects due to the Au substrate were observed up to 5 Pd ML. Influence of benzotriazole (BTA) on H sorption was also investigated. BTA blocked H adsorption above 250 mV vs. RHE. At less positive potentials adsorbed BTA layer seemed to undergo a reorientation allowing H adsorption. Stationary and dynamic electrochemical impedance spectroscopy was used to obtain double layer capacitance and charge transfer resistance. BTA also promoted kinetically H sorption into Pd/Au(1 1 1) monolayer and Pd/Au(polycrystal) nanometric deposits.

  19. Glassy crystalline state and water sorption of alkyl maltosides.

    Science.gov (United States)

    Kocherbitov, Vitaly; Söderman, Olle

    2004-04-13

    A differential scanning calorimetric and sorption calorimetric study of two alkyl maltosides, C8G2 and C10G2, was performed. In the dry state, C8G2 and C10G2 do not form solid crystals but undergo a glass transition upon temperature change. The glass is partly ordered and has the same lamellar structure as the liquid crystals formed by the two maltosides. To reflect the presence of the glass transition and the structure, the terms "glassy crystals" and "glassy liquid crystals" can be used. A mechanism of the relaxation of the glassy crystals based on the results of small-angle X-ray scattering experiments is proposed. Experiments on water sorption showed that the glassy crystals turn into lyotropic liquid crystals upon sorption of water at constant temperature. This isothermal glass transition can be characterized by water content and change of partial molar enthalpy of mixing of water. A method to calculate the phase diagram liquid crystals-glassy liquid crystals is proposed.

  20. Adsorption isotherm special study. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-05-01

    The study was designed to identify methods to determine adsorption applicable to Uranium Mill Tailings Remedial Action (UMTRA) Project sites, and to determine how changes in aquifer conditions affect metal adsorption, resulting retardation factors, and estimated contaminant migration rates. EPA and ASTM procedures were used to estimate sediment sorption of U, As, and Mo under varying groundwater geochemical conditions. Aquifer matrix materials from three distinct locations at the DOE UMTRA Project site in Rifle, CO, were used as the adsorbents under different pH conditions; these conditions stimulated geochemical environments under the tailings, near the tailings, and downgradient from the tailings. Grain size, total surface area, bulk and clay mineralogy, and petrography of the sediments were characterized. U and Mo yielded linear isotherms, while As had nonlinear ones. U and Mo were adsorbed strongly on sediments acidified to levels similar to tailings leachate. Changes in pH had much less effect on As adsorption. Mo was adsorbed very little at pH 7-7.3, U was weakly sorbed, and As was moderately sorbed. Velocities were estimated for metal transport at different pHs. Results show that the aquifer materials must be characterized to estimate metal transport velocities in aquifers and to develop groundwater restoration strategies for the UMTRA project.

  1. Settlement determination of operating moisture of autoclaved aerated concrete in different climatic zones

    Directory of Open Access Journals (Sweden)

    Pastushkov Pavel Pavlovich

    Full Text Available In the process of operation of buildings the moisture state of enveloping structures materials is changing depending on their construction features, properties of the material, temperature and moisture conditions in the premises, climatic conditions of the construction area. Moisture mode determines the operational properties of the enveloping structures of a building. It directly influences the thermal characteristics of enveloping structure and energy efficiency of the applied materials. The analysis of the methods for calculation of moisture behavior of enclosing structures is carried out. The research relevance of operational moisture of AAC is substantiated. Experimental studies and results of the sorption moisturizing and water vapor permeability of leading marks of aerated concrete are carried out. The authors offer the results of numerical calculations of the moisture behavior of aerated concrete in the walls with mark D400 with facade thermal insulation composite systems - with external plaster layers for different climatic zones of construction.

  2. Preparation and hydrogen sorption properties of Mg-Cu-Y-H systems

    Institute of Scientific and Technical Information of China (English)

    LI Zhinian; LIU Xiaopeng; HUANG Zuo; JIANG Lijun; WANG Shumao

    2006-01-01

    Mg-xwt.%CuY (x=15, 20, 25) composites were successfully prepared by reactive mechanical alloying (RMA).X-ray diffraction (XRD) measurement shows that main phases of the as milled composites are MgH2 and Mg2Cu, and they converted into Mg and MgCu2 after dehydrogenation, respectively.Pressure-Composition-Isotherm (PCI) test shows that the composites exhibit double pressure plateau at each isothermal desorption process.The hydrogen absorption and desorption kinetics of the composites become worse with increasing x content, indicating that Mg-Cu phase has a negative effect on the hydrogen sorption properties of the composites.It is supposed that the good hydrogen sorption properties of the composites attribute to the catalyst effect of yttrium hydride distributed in Mg substrate and the particles size reduction and crystal defects formed by RMA.

  3. Hydrophobic and moisture-stable metal–organic frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Carlos A.; Nune, Satish K.; Annapureddy, Harsha V.; Dang, Liem X.; McGrail, B. Peter; Zheng, Feng; Polikarpov, Evgueni; King, David L.; Freeman, Charles J.; Brooks, Kriston P.

    2015-08-15

    Metal-organic frameworks (MOFs) have proved to be very attractive for applications including gas storage, separation, sensing and catalysis. In particular, CO2 separation from flue gas in post-combustion processes is one of the main focuses of research among the scientific community. One of the major issues that are preventing the successful commercialization of these novel materials (e.g., MgDOBDC and NiDOBDC) is their high affinity towards water that not only compromises gas sorption capacity but also the chemical stability. In this paper, we demonstrate a novel post-synthesis modification approach to modify MOFs towards increasing hydrophobic behavior and chemical stability against moisture without compromising CO2 sorption capacity. Our approach consists of incorporating hydrophobic moieties on the external surface of the MOFs via physical adsorption. The rationale behind this concept is to increase the surface hydrophobicity in the porous materials without the need of introducing bulky functionalities inside the pore which compromises the sorption capacity toward other gases. This allows MOF interaction/sorption of CO2 molecules comparable to unmodified MOFs. We herein report preliminary results on three routinely studied MOF materials [MIL-101(Cr), MgDOBDC and NiDOBDC] demonstrating that the polymer-modified MOFs retain CO2 sorption capacity while reducing the water adsorption up to three times, respect to the un-modified materials, via an equilibrium effect. Furthermore, the water stability of the polymer-functionalized MOFs is significantly higher than the water stability of the bare material. Molecular dynamic simulations demonstrated that this equilibrium effect implies a fundamental and permanent change in the water sorption capacity of MOFs. This approach can also be employed to render moisture stability and selectivity to MOFs that find applications in gas separations, catalysis and sensing where water plays a critical role in compromising MOF

  4. Isotermas de adsorção do pedúnculo seco do caju Adsorption isotherms of the dry cashew apple

    Directory of Open Access Journals (Sweden)

    Siumara R. Alcântara

    2009-02-01

    Full Text Available A atividade de água constitui um fator importante no processo de fermentação semi-sólida, haja vista sua relação com a quantidade de água disponível ao microrganismo responsável pelo metabolismo do produto, sendo necessário à obtenção de isotermas de sorção para caracterização do substrato. Ante o exposto, objetivou-se a construção das isotermas de adsorção do pedúnculo seco do caju (Anacardium occidentale L. nas temperaturas usuais de fermentação (25, 30, 35 e 40 ºC. Ajustaram-se as isotermas com os modelos de BET, GAB, Oswin, Henderson e Smith. Observou-se que o modelo de GAB apresentou melhor ajuste, de vez que, na faixa de atividade de água que maximiza a biossíntese do microrganismo, para produção de pectinases por Aspergillus niger, a umidade do substrato deve estar acima de 35% b.s.Water activity is a very important factor in a solid state fermentation process due to its relation with the water quantity available to the microorganism that will synthesize the product. Therefore, it is necessary to obtain the sorption isotherms for the characterization of the substrate. The objective of this study is to obtain adsorption isotherms of the dry cashew apple (Anacardium occidentale L. at normal temperatures of fermentation process (25, 30, 35 e 40 ºC. Five mathematical models were fitted to the experimental data: BET, GAB, Oswin, Henderson e Smith. The GAB model was better fitted to the product. The isotherms allowed the determination of the appropriate moisture content to obtain the water activities that maximize the biosynthesis of the microorganism for the pectin production by solid state fermentation process. The moisture content of the substrate should be above 35% d.b.

  5. Agro-waste biosorbents: Effect of physico-chemical properties on atrazine and imidacloprid sorption.

    Science.gov (United States)

    Mandal, Abhishek; Singh, Neera; Nain, Lata

    2017-07-05

    Low cost agro-waste biosorbents namely eucalyptus bark (EB), corn cob (CC), bamboo chips (BC), rice straw (RS) and rice husk (RH) were characterized and used to study atrazine and imidacloprid sorption. Adsorption studies suggested that biosorbents greatly varied in their pesticide sorption behaviour. The EB was the best biosorbent to sorb both atrazine and imidacloprid with KF values of 169.9 and 85.71, respectively. The adsorption isotherm were nonlinear in nature with slope (1/n) values lacunarity and relative C-O band intensity parameters of biosorbents. Probably, both physisorption and electrostatic interactions were responsible for the pesticide sorption. The eucalyptus bark can be exploited as low cost adsorbent for the removal of these pesticides as well as a component of on-farm biopurification systems.

  6. Preparation of Polysulfone-supported Phosphoramidic Acid Type Chelate Membrane and Its Sorption Properties for Ag+

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; CUI Yong-fang; DU Qi-yun; PEI Guang-ling

    2002-01-01

    A blending chelate filter membrane with high chelate capacity for Ag+ has been prepared by blending of phosphoramidic acid resin and polysulfone. The major parameters influencing structure of the chelate filter membranes such as the blending ratio, phosphoramidic acid resin grain size and temperature of casting solution have been studied. The relationship among the chelate amount of Ag+, pH value, Ag+ concentration and phosphoramidic acid resin grain diameter were examined. The chelate filter membrane had a capacity of1438μg/cm2 for Ag+ under appropriate conditions.Sorption isotherm of Ag + could be expressed with the Freundlich sorption model. The dynamic chelate experiments proved that the sorption and desorption of membranes could be realized simultaneously for Ag+.

  7. Sorption of wastewater containing reactive red X-3B on inorgano-organo pillared bentonite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Bentonite is a kind of natural clay with good exchanging ability. By exchanging its interlamellar cations with various soluble cations, such as quaternary ammonium cations and inorganic metal ions, the properties of natural bentonite can be greatly improved. In this study, hexadecyltrimethylammonium bromide (HDTMA), CaCl2, MgCl2, FeCl3, AlCl3 were used as organic and inorganic pillared materials respectively to produce several kinds of Ca-, Mg-, Fe-, Al-organo pillared bentonites. Sorption of reactive red X-3B on them was studied to determine their potential application as sorbents in wastewater treatment. The results showed that these pillared bentonites had much improved sorption properties, and that the dye solutions' pH value had some effect on the performance of these inorgano-organo pillared bentonites. Isotherms of reactive X-3B on these pillared bentonites suggested a Langmuir-type sorption mechanism.

  8. Investigation of acetylated kapok fibers on the sorption of oil in water

    Institute of Scientific and Technical Information of China (English)

    Jintao Wang; Yian Zheng; Aiqin Wang

    2013-01-01

    Kapok fibers have been acetylated for oil spill cleanup in the aqueous environment.The structures of raw and acetylated kapok fiber were characterized using Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM).Without severe damage to the lumen structures,the kapok fibers were successfully acetylated and the resulting fibers exhibited a better oil sorption capacity than raw fibers for diesel and soybean oil.Compared with high viscosity soybean oil,low viscosity diesel shows a better affinity to the surface of acetylated fibers.Sorption kinetics is fitted well by the pseudo second-order model,and the equilibrium data can be described by the Freundlich isotherm model.The results implied that acetylated kapok fiber can be used as the substitute for non-biodegradable oil sorption materials.

  9. Sorption of phenanthrene and benzene on differently structural kerogen: important role of micropore-filling.

    Science.gov (United States)

    Zhang, Yulong; Ma, Xiaoxuan; Ran, Yong

    2014-02-01

    Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23-46% and 36-65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling.

  10. Effects of dissolved organic matter from sewage sludge on the atrazine sorption by soils

    Institute of Scientific and Technical Information of China (English)

    LING Wanting; XU Jianming; GAO Yanzheng

    2005-01-01

    The effects of dissolved organic matter (DOM), water soluble organic matter derived from sewage sludge, on the sorption of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trazine) by soils were studied using a batch equilibrium technique. Six paddy soils, chosen so as to have different organic carbon contents, were experimented in this investigation. Atrazine sorption isotherms on soils were described by the linear equation, and the distribution coefficients without DOM (Kd) or with DOM (Kd*) were obtained. Generally, the values of Kd*/Kd initially insoil-solution system form. Critical concentrations of DOM (DOMnp) were obtained where the value of Kd* was equal to Kd. The presence of DOM with concentrations lower than DOMnp promoted atrazine sorption on soils (Kd* > Kd), whereas the presence of DOM with concentrations higher than DOMnp tended to inhibit atrazine sorption (Kd* < Kd). Interestingly, DOMnp for tested soils was negatively correlated to the soil organic carbon content, and the maximum of Kd*/Kd (i.e.Kmax) correlated positively with the maximum of DOM sorption on soil (Xmax). Further investigations showed that the presence of hydrophobic fraction of DOM evidently promoted the atrazine sorption on soils, whereas the presence of hydrophilic DOM fraction obviously tended to inhibit the atrazine sorption. Interactions of soil surfaces with DOM and its fractions were suggested to be the major processes determining atrazine sorption on soils. The results of this work provide a reference to the agricultural use of organic amendment such as sewage sludge for improving the availability of atrazine in soils.

  11. Effect of glutamic acid on copper sorption onto kaolinite - Batch experiments and surface complexation modeling.

    Science.gov (United States)

    Karimzadeh, Lotfollah; Barthen, Robert; Stockmann, Madlen; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna

    2017-07-01

    High carbonate content of the European Kupferschiefer ore deposits is a challenge for acid copper leaching (pH ≤ 2). Therefore investigating the mobility behavior of Cu(II) under conditions related to an alternative, neutrophil biohydrometallurgical Cu(II) leaching approach is of interest. As glutamic acid (Glu) might be present as a component in the growth media, we studied its effects on the adsorption of Cu(II) onto kaolinite. The binary and ternary batch sorption measurements of Cu(II) and Glu onto kaolinite were performed in the presence of 10 mM NaClO4 as background electrolyte and at a pH range from 4 to 9. Sorption experiments were modeled by the charge-distribution multi-site ion complexation (CD-MUSIC) model by using single sorption site (≡SOH) and monodentate surface complexation reactions. Glu sorption on kaolinite is weak (<10%) and independent of pH. Furthermore, Glu slightly enhances the Cu(II) sorption at low pH but strongly hinders (up to 50%) the sorption at higher pH and therewith enhances copper mobility. The results of isotherms show that Cu(II)-Glu sorption onto kaolinite mimics the Freundlich model. The proposed CD-MUSIC model provides a close fit to the experimental data and predicts the sorption of Cu(II), Cu(II)-Glu and Glu onto kaolinite as well as the effect of Glu on Cu(II) mobility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Sorption of indigo carmine by a Fe-zeolitic tuff and carbonaceous material from pyrolyzed sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Segura, E. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Paseo Colon y Tollocan s/n., C.P. 50000 Toluca (Mexico); Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico); Solache-Rios, M., E-mail: marcos.solache@inin.gob.mx [Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico); Colin-Cruz, A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Paseo Colon y Tollocan s/n., C.P. 50000 Toluca (Mexico)

    2009-10-30

    Indigo carmine removal from aqueous solution has been evaluated using Fe-zeolitic tuff and carbonaceous material from pyrolyzed sewage sludge treated with HCl (CM). The adsorbents were characterized by scanning electron microscopy, BET surface area and X-ray diffraction. Sorption kinetics and isotherms were determined and the adsorption behaviors analyzed. Kinetic pseudo-second order and Langmuir-Freundlich models were successfully applied to the experimental results obtained with the Fe-zeolitic material, while kinetic first order and Langmuir-Freundlich models were applied to the results from the carbonaceous materials. This indicates mechanisms of chemisorption and physic sorption, respectively, on the heterogeneous materials. The results indicate that the carbonaceous material from the pyrolysis of sewage sludge (sorption capacity 92.83 mg/g) is a better adsorbent of indigo carmine than the zeolitic material (sorption capacity 32.83 mg/g).

  13. Sorption and Transport of Sildenafil in Natural Soils

    Science.gov (United States)

    Boudinot, F. G.; Vulava, V. M.

    2013-12-01

    Pharmaceutical Chemicals (PCs) mainly enter our ecosystems from discharges of treated wastewater and have direct effects on the ecological health of that area. Sildenafil citrate (Viagra) is one such PC, whose presence has been reported in stream waters. Although one study has shown that sildenafil is not harmful in bacterial and fungal environments, there remains much unknown about its fate elsewhere in ecosystems. Sildenafil is a complex organic molecule with two amino functional groups that result in pKa's of 7.27 and 5.97. It also has a high solubility of 3.5 g/L. Given that sildenafil consumption (and concurrently disposal) is on the rise, it is essential that its behavior in the natural environment be better understood. The goal of this study was to quantify the sorption and transport behavior of sildenafil in differing natural soils with varying compositions. Pristine A- and B- horizon soil samples from several soil series were collected in a managed forest near Charleston, SC and used for these studies. The soils were characterized for physical and chemical properties: soil organic matter content ranged between 0.6-7.6%, clay content between 6-20%, and soil pH between 4-5. These soils were then used to perform kinetic reaction, sorption, and column transport experiments. Batch kinetic experiments showed a fast reaction rate in both clay-rich and organic-rich soils and an equilibration time of less than 24 hours. Batch reactor sorption experiments provided data for sorption isotherms (plot of sildenafil in solution, C vs. sildenafil sorbed in soil, q) which were nonlinear. The isotherms were fit using Freundlich model (q=KfCn, where Kf and n are fitting parameters). Sildenafil sorbed more strongly to clay-rich soils compared with organic-rich soils with less clay. It is hypothesized that permanent negative charge on clay mineral surfaces form ionic bonds with positively charged amines in sildenafil in acidic pHs. Transport experiments were conducted using

  14. Sorption of Atrazine in Tropical Soil by Biochar Prepared from Cassava Waste

    Directory of Open Access Journals (Sweden)

    Hui Deng

    2014-09-01

    Full Text Available Biochar (BC is a carbonaceous and porous product generated from the incomplete combustion of biomass and has been recognized as an efficient adsorbent. This study evaluated the ability of BC to sorb atrazine pesticide in tropical soil, and explored potential environmental values of BC on mitigating organic micro-pollutants. BC was produced from cassava waste via pyrolyzation under oxygen-limiting conditions at 350, 550, and 750 °C (MS350, MS550, and MS750, respectively. Three biochars were characterized and investigated as sorbents for the removal atrazine from tropical soil. BC pyrolyzed at higher temperatures more quickly reached equilibrium. The pseudo-second-order model perfectly simulated the sorption kinetics for atrazine with the coefficients R2 above 0.996, and the sorption amount at equilibrium (qe was 0.016 mg/g for MS350, 0.025 mg/g for MS550 and 0.050 mg/g for MS750. The isotherms of MS350 displayed relatively linear behavior, whereas the sorption of atrazine on MS550 and MS750 followed a nonlinear isotherm. The sorption data were well described by the Freundlich model with logKF of 0.476 for MS350, 0.771 for MS550, 1.865 for MS750. A thermodynamic study indicated that the sorption of atrazine in BC-added soil was a spontaneous and endothermic process and was primarily controlled by physisorption. In addition, lower pH was conducive to the sorption of atrazine in BC-added soil.

  15. Sorption irreversibility of 1,4-dichlorobenzene in two natural organic matter-rich geosorbents.

    Science.gov (United States)

    Sander, Michael; Pignatello, Joseph J

    2009-03-01

    Hysteresis, a frequently observed phenomenon in sorption studies, is inconsistent with the key assumption of sorption reversibility in most fate and bioavailability models. Therefore, a study of the underlying causes of hysteresis is essential. Carbon-radiolabeled 1,4-dichlorobenzene (DCB) isotope tracer exchange was carried out at select points along the isotherms of DCB in a brown coal and a peat soil, holding total DCB concentration constant. Tracer exchange was performed both in the forward (sorption) and reverse (desorption) directions at the bulk sorption points and in the desorption direction at the corresponding bulk desorption points. Bulk DCB isotherms showed concentration-dependent hysteresis. However, tracer reequilibration in all cases was consistent with free exchange between sorbed and aqueous-phase molecules. These results rule out common experimental artifacts and demonstrate that sorption of bulk DCB is truly hysteretic (i.e., irreversible). The differences in rates between bulk and tracer sorption and desorption are consistent with the coupling of bulk DCB diffusion to other processes that retard equilibration, which we assign to matrix swelling or shrinking. Hysteresis is attributed to matrix deformation--specifically, to inelastic expansion and creation of voids accommodating sorbate molecules in the matrix, which leads to enhanced affinity in the desorption step. Comparing the results to previous results for naphthalene in the coal, we find that irreversible effects are similar for DCB and naphthalene in the coal but differ for DCB between the two sorbents. An explanation based on the different physical properties of these sorbents is provided. Solid-phase extraction of equilibrated DCB with Tenax revealed a highly desorption-resistant fraction. While too small to account for the observed hysteresis, this fraction may represent molecules that become trapped as the matrix collapses and simultaneously stiffens during abrupt desorption.

  16. Sulfamethazine Sorption to Soil: Vegetative Management, pH, and Dissolved Organic Matter Effects.

    Science.gov (United States)

    Chu, Bei; Goyne, Keith W; Anderson, Stephen H; Lin, Chung-Ho; Lerch, Robert N

    2013-01-01

    Elucidating veterinary antibiotic interactions with soil is important for assessing and mitigating possible environmental hazards. The objectives of this study were to investigate the effects of vegetative management, soil properties, and >1000 Da dissolved organic matter (DOM) on sulfamethazine (SMZ) behavior in soil. Sorption experiments were performed over a range of SMZ concentrations (2.5-50 μmol L) using samples from three soils (Armstrong, Huntington, and Menfro), each planted to one of three vegetation treatments: agroforestry buffers strips (ABS), grass buffer strips (GBS), and row crops (RC). Our results show that SMZ sorption isotherms are well fitted by the Freundlich isotherm model (log = 0.44-0.93; Freundlich nonlinearity parameter = 0.59-0.79). Further investigation of solid-to-solution distribution coefficients () demonstrated that vegetative management significantly ( GBS > RC). Multiple linear regression analyses indicated that organic carbon (OC) content, pH, and initial SMZ concentration were important properties controlling SMZ sorption. Study of the two most contrasting soils in our sample set revealed that increasing solution pH (pH 6.0-7.5) reduced SMZ sorption to the Armstrong GBS soil, but little pH effect was observed for the Huntington GBS soil containing 50% kaolinite in the clay fraction. The presence of DOM (150 mg L OC) had little significant effect on the Freundlich nonlinearity parameter; however, DOM slightly reduced SMZ values overall. Our results support the use of vegetative buffers to mitigate veterinary antibiotic loss from agroecosystems, provide guidance for properly managing vegetative buffer strips to increase SMZ sorption, and enhance understanding of SMZ sorption to soil.

  17. Phosphorus sorption, desorption and resorption by soils of the Brazilian Cerrado supporting eucalypt

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Nairam F. Filho [Universidade Federal de Santa Maria, Dept. de Ciencia Florestal, Porto Alegre, RS (Brazil); Comerford, N.B. [Florida Univ., Soil and Water Science Dept., Gainesville, FL (United States); Barros, Nairam F. [Universidade Federal de Vicosa, Dept. do Solos, Vicosa, MG (Brazil)

    2005-02-01

    Oxisols of the Brazilian Cerrado are highly weathered phosphorus deficient soils, on which eucalypt is increasingly being grown as a source of carbon and energy for steel manufacturing. Phosphorus (P) fertilization is a necessary practice to assure adequate eucalypt production; therefore, an understanding of cycling by inorganic soil P should lead to efficient P management and more accurate modeling of P bioavailability. Since sorption and desorption reactions control inorganic P bioavailability, the purpose of this study was to contrast P sorption, desorption and subsequent resorption for a range of Cerrado soils. Its specific objectives were to determine (i) if desorption and resorption show the same hysteresis shown by sorption and desorption, (ii) if K{sub d} values of resorption and desorption for Cerrado soils are dependent on the soil's clay content and (iii) if resorption and desorption K{sub d} values are a function of the amount of labile P on the soil surface. Three levels of P were sorbed onto four Cerrado soils with clay contents between 13% and 81%. Phosphorus desorption was measured using anion-exchange membranes. Sorption was a function of soil clay content, and a pedotransfer function for the soil partition coefficient was calculated with an r{sup 2} = 0.99. Desorption and resorption were dependent on both the clay content of the soil (r{sup 2} = 0.59-0.99) and the amount of sorbed labile P. Pedotransfer functions for each of these processes depend on accurate measurement of the inorganic P that responds to disequilibria exchange. Desorption and resorption were not hysteretic; yet desorption was hysteretic with the original sorption isotherm. This suggests the question: how useful are commonly produced sorption isotherms? (Author)

  18. The dynamics of H 2 and N 2 sorption in carbon nanotubes

    Science.gov (United States)

    Ötvös, Zs.; Onyestyák, Gy.; Valyon, J.; Kiricsi, I.; Kónya, Z.; Rees, L. V. C.

    2004-11-01

    Single-walled and multi-walled carbon nanotubes (SWNT and MWNT) were prepared by catalytic decomposition of methane and acetylene, respectively. The resulting catalyst/carbon composites were subjected to chemical treatments to obtain samples which were enriched in nanotubes. Isotherms and frequency response (FR) spectra of N2 and H2 were recorded at 195 and 77 K, respectively, in the 1-800 Pa pressure range. The adsorption isotherms for N2 were found to obey Henry's law, while the isotherms of H2 adsorption indicated some energetic heterogeneity of the sorption sites. Stronger adatom-substrate interaction was detected for those samples which had been subjected to oxidative treatment. The FR measurements showed that treatment of MWNT in KMnO4 solution changed the rate-controlling mechanism of mass transport from one of sorption to one of diffusion. Results substantiated that the surface functional groups, generated by the oxidative treatment, have significant influence on both the equilibrium and the dynamic N2 and H2 sorption properties of the carbon nanotubes.

  19. Hydrogen isotherms in palladium loaded carbon nanotubes and activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M. T.; Anson, A.; Lafuente, E.; Urriolabeitia, E.; Navarro, R.; Benito, A. M.; Maser, W. K.

    2005-07-01

    Session 5a In order to increase the hydrogen sorption capacity of carbon materials, a sample of single-wall carbon nanotubes (SWNTs) and the activated carbon MAXSORB have been loaded with palladium nanoparticles. While carbon materials adsorb hydrogen due to physical interactions, palladium can capture hydrogen into the bulk structure or chemically react to form hydrides. Experiental SWNTs have been synthesized in an electric arc reactor, using Ni and Y as catalysts in a 660 mbar He atmosphere. MAXSORB is a commercial activated carbon obtained from petroleum coke through a chemical treatment with KOH. Palladium has been deposited over the carbon support by means of a reflux method in a solution of an organometallic complex. Different samples have been prepared depending on the weight ratio (Carbon material / Pd) in the original reactants. The effectiveness of the deposition method has been examined by means of X-ray diffraction (XRD), induction coupled plasma spectrometry (ICPS) and transmission electron microscopy (TEM). The volumetric system Autosorb-1 from Quantachrome Instruments has been used to obtain the nitrogen adsorption isotherms at 77 K for all the materials. The hydrogen isotherms at 77 K and room temperature and up to 800 torr have also been obtained in the Autosorb-1. The BET specific surface area and the micropore volume have been calculated from the nitrogen adsorption data. High pressure hydrogen isotherms up to 90 bar have been carried out at room temperature in a VTI system provided with a Rubotherm microbalance. (Author)

  20. Sorption phenomena of PCBs in environment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The relationship between the properties of PCBs and the behavior of soil and sediment is reviewed. The sorption phenomena of PCBs in the environment are described with different models. The research progress on the sorption mechanisms is also discussed.

  1. Sorption of Am(Ⅲ) on Na-bentonite: Effect of pH, ionic strength,temperature and humic acid

    Institute of Scientific and Technical Information of China (English)

    Tao Yu; Wang Suo Wu; Qiao Hui Fan

    2012-01-01

    Sorption of Am(Ⅲ) on Na-bentonite as a function of contact time,pH,ionic strength,humic acid (HA) and temperature was investigated under ambient conditions.The results showed that the sorption was strongly dependent on pH and ionic strength.Am(Ⅲ) sorption can be described well by pseudo-second-order model.The presence of HA takes a positive effect at low pH; but a negative influence under high pH range.Enthalpy,entropy and Gibbs free energy (i.e.,AH0,AS0 and AG0) calculated from sorption isotherms suggested that sorption process of Am(Ⅲ) was spontaneous and endothermic.

  2. The effect of changing ambient humidity on moisture condition in timber elements

    DEFF Research Database (Denmark)

    Hozjan, Tomaž; Turk, Goran; Srpcic, Stanislav;

    2012-01-01

    fully coupled transport model including a model for the influential sorption hysteresis of wood is used. The coupled model accounts for both vapor transport in pores and bound water transport in wood tissue. Moisture state history influences relationship between moisture state of wood and air humidity......, it must therefore be taken into account. In order to include history dependency, a hysteresis model is used here. Numerical results for timber specimen exposed to combined daily and annually cyclic variation of outside humidity are presented....

  3. Effect of sediment properties on the sorption of C{sub 12}-2-LAS in marine and estuarine sediments

    Energy Technology Data Exchange (ETDEWEB)

    Rico-Rico, Angeles [Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3508 TD Utrecht (Netherlands)], E-mail: a.ricorico@uu.nl; Temara, Ali [Procter and Gamble Company, Central Product Safety, Temselaan 100, 1853 Strombeek-Bever (Belgium); Behrends, Thilo [Department of Earth Sciences-Geochemistry, Faculty of Geosciences, Utrecht University, 3508 TA Utrecht (Netherlands); Hermens, Joop L.M. [Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 2, 3508 TD Utrecht (Netherlands)

    2009-02-15

    Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments. C{sub 12}-2-LAS was used as a model compound. Sorption to the clays montmorillonite and kaolinite resulted in non-linear isotherms very similar for both clays. When reducing the organic content, sorption coefficients decreased proportionally to the fraction removed in fine grain sediments but this was not the case for the sandy sediment. The correlation of the sediment characteristics with the sorption coefficients at different surfactant concentrations showed that at concentrations below 10 {mu}g C{sub 12}-2-LAS/L, the clay content correlated better with sorption, while the organic fraction became more significant at higher concentrations. - Sorption of C{sub 12}-2-LAS to marine sediments mainly depends on both clay and organic carbon content. The importance of each parameter varies with the surfactant concentration.

  4. Alginate and Algal-Based Beads for the Sorption of Metal Cations: Cu(II) and Pb(II)

    Science.gov (United States)

    Wang, Shengye; Vincent, Thierry; Faur, Catherine; Guibal, Eric

    2016-01-01

    Alginate and algal-biomass (Laminaria digitata) beads were prepared by homogeneous Ca ionotropic gelation. In addition, glutaraldehyde-crosslinked poly (ethyleneimine) (PEI) was incorporated into algal beads. The three sorbents were characterized by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX): the sorption occurs in the whole mass of the sorbents. Sorption experiments were conducted to evaluate the impact of pH, sorption isotherms, and uptake kinetics. A special attention was paid to the effect of drying (air-drying vs. freeze-drying) on the mass transfer properties. For alginate, freeze drying is required for maintaining the porosity of the hydrogel, while for algal-based sorbents the swelling of the material minimizes the impact of the drying procedure. The maximum sorption capacities observed from experiments were 415, 296 and 218 mg Pb g−1 and 112, 77 and 67 mg Cu g−1 for alginate, algal and algal/PEI beads respectively. Though the sorption capacities of algal-beads decreased slightly (compared to alginate beads), the greener and cheaper one-pot synthesis of algal beads makes this sorbent more competitive for environmental applications. PEI in algal beads decreases the sorption properties in the case of the sorption of metal cations under selected experimental conditions. PMID:27598128

  5. 十六烷基三甲基季铵阳离子改良二氧化硅对酸性染料的吸着%Sorption of Acid Dyes onto Silica Modified with Cetyltrimethylammonium Cations

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The sorption behavior of acid dyes onto cetyltrimethylammonium bromide (CTAB)- modified silica as a function of pH in the aqueous medium was studied. Single- and multi-solute sorption equilibria of orange Ⅱ(OR),phenol red (PR) and Eriochrome Black T (EBT) were studied at pH 3, unbuffered water pH and pH 11. Sorption behavior of EBT could not be conducted at pH 3 due to its aggregation in acidic medium. All the reaction conditions,experimental protocols and techniques remained the same throughout the sorption process. Sorption isotherms for single-solute system were fitted by the Langmuir model, while Langmuir competitive model (LCM) and the ideal adsorbed solution theory (IAST) coupled with Langmuir model (IAST/Langmuir) were used for the prediction of multisolute competitive sorption. Sorption affinities influenced by the factors like physical interactive forces between the molecules of CTA on silica and sorbate, structural limitations of the dyes based on their geometrical arrangement were investigated. Sorption affinity of OR was found to be higher than that of EBT and PR at all the pH values investigated. Magnitude of the sorption capacities was observed to be higher in acidic medium but lower in alkaline medium. Trends of the sorption affinities in multisolute system were similar to those in single-solute system but magnitude of the sorption capacities was significantly reduced due to the prevailing competition among the sorbates.

  6. Atrazine sorption by biochar, tire chips, and steel slag as media for blind inlets: A kinetic and isotherm sorption approach

    Science.gov (United States)

    Surface inlets are installed in subsurface drainage systems to reduce ponding duration and surface runoff, but can contribute to water quality concerns by allowing water to directly enter buried drains. Blind inlets, consist of perforated pipes covered with gravel and are separated from an overlying...

  7. Equilibrium isotherms and isosteric heat of pepper variety bico (Capsicum chinense Jacq.

    Directory of Open Access Journals (Sweden)

    Philipe dos Santos

    2015-01-01

    Full Text Available During processing, the storage requires attention, since the moisture content is a major factor that influences the quality of raw materials and manufactured products. Equilibrium isotherm represents the relationship between the material moisture content and water activity for a given temperature, providing important information for use in industrial operations such as drying and storage. This study aimed to determine the equilibrium isotherms of peppers variety bico (Capsicum chinense Jacq. in whole and paste forms, calculate the isosteric heat of desorption and determine its behavior. To this end, we used six mathematical models to fit experimental data of desorption isotherms. The GAB model fitted well the experimental desorption data of pepper variety bico, in paste and whole forms. The isosteric heat obtained for the whole form was higher than for the paste form.

  8. Moisture buffer capacity of different insulation materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2004-01-01

    There is an increasing focus on the possibilities of utilizing the absorptive ability of porous materials to create passive control of humidity variations in the indoor air. These variations result in peaks in the indoor air humidity due to moisture production, or in the exterior building envelope...... due to the diurnal variations of outdoor air temperature and humidity. A passive control of the humidity of the indoor air - particularly together with passive thermal control - may lead to smaller energy use for climatization of buildings. For exterior envelopes, the choice of right materials can...... lead to more durable constructions. In this paper, a large range of very different thermal insulation materials have been tested in specially constructed laboratory facilities to determine their moisture buffer capacity. Both isothermal and nonisothermal experimental set-ups have been used...

  9. Bound water measurement methods and moisture distribution within sewage sludge%污泥结合水测量方法和水分分布特性

    Institute of Scientific and Technical Information of China (English)

    谢浩辉; 麻红磊; 池涌; 马增益

    2012-01-01

    为了实现污泥高效脱水,对污泥水分分布特征与脱水性能变化的关系进行研究.分别利用热干燥法、抽滤法、压滤法、水活度法和膨胀计法测定同一市政污泥的结合水相对质量分数,通过分析比较测量数据和应用原理,总结出各种方法的优缺点和适用条件.基于膨胀计法对污泥水分能量状态进行了分析,构建了污泥水分分布特征曲线,并阐明污泥在不同水分质量分数时的机械脱水效果.研究表明:5种方法的结合水质量分数(结合水/干基)测量结果差异明显,其中抽滤法测量值最大为628%,水活度法测量值最小,只有34%;膨胀计法操作快捷、原始数据容易处理,优于其余4种测量方法.当污泥水分相对质量分数(全水分/干基)大于183%时,适当提高设备的脱水强度能够较好地改善脱水效果.%Relationship between sludge moisture distribution and dewatering performance was studied to achieve effective dewatering of sewage sludge. Five measurement methods, including drying test, filtration test, expression test, sorption isotherms test and dilatometric test were applied to determine the bound water content within a typical sewage sludge sample. Features and applicable conditions of each method were obtained via analysis and comparison of their measurement data and theories. A sludge moisture distribution curve was constructed via analysis of the sludge moisture energy status in dilatometric method, which could be utilized to elucidate the sludge dewatering performance at different moisture contents. The experimental results indicate that the sludge bound water measurement results from five methods are different, and the maximum data of 628% mass fraction of the sludge bound water (bound water/ dry water) measurement result is obtained from filtration test whereas the minimum data of 34% from sorption isotherms test. The dilatometric method is preferable to the other methods due to its

  10. KINETICS OF NON-ISOTHERMAL CRYSTALLIZATION

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhiying; CAO Zhenlin

    1990-01-01

    A kinetic equation of non-isothermal crystamzation was derived by extending Avrami's equation to the non-isothermal situation. More crystallization information can be obtained from this kinetic equation. The curves of non-isothermal and isothermal crystallizations were analysed and compared for poly (ethylene terephthalate ) (PET), and the results were discussed.

  11. Oil sorption by lignocellulosic fibers

    Science.gov (United States)

    Beom-Goo. Lee; James S. Han; Roger M. Rowell

    1999-01-01

    The oil sorption capacities of cotton fiber, kenaf bast fiber, kenaf core fiber, and moss fiber were compared after refining, extraction, and reduction in particle sizes. The tests were conducted on diesel oil in a pure form. Cotton fiber showed the highest capacity, followed by kenaf core and bast fibers. Wetting, extraction, and reduction in particle size all...

  12. Kinetic and isotherm studies of Cu(II) biosorption onto valonia tannin resin

    Energy Technology Data Exchange (ETDEWEB)

    Sengil, I. Ayhan [Department of Environmental Engineering, Engineering Faculty, Sakarya University, 54100 Sakarya (Turkey)], E-mail: asengil@sakarya.edu.tr; Ozacar, Mahmut [Department of Chemistry, Science and Arts Faculty, Sakarya University, 54100 Sakarya (Turkey); Tuerkmenler, Harun [Institute of Sciences and Technology, Sakarya University, 54040 Sakarya (Turkey)

    2009-03-15

    The biosorption of Cu(II) from aqueous solutions by valonia tannin resin was investigated as a function of particle size, initial pH, contact time and initial metal ion concentration. The aim of this study was to understand the mechanisms that govern copper removal and find a suitable equilibrium isotherm and kinetic model for the copper removal in a batch reactor. The experimental isotherm data were analysed using the Langmuir, Freundlich and Temkin equations. The equilibrium data fit well in the Langmuir isotherm. The experimental data were analysed using four sorption kinetic models - the pseudo-first- and second-order equations, the Elovich and the intraparticle diffusion model equation - to determine the best fit equation for the biosorption of copper ions onto valonia tannin resin. Results show that the pseudo-second-order equation provides the best correlation for the biosorption process, whereas the Elovich equation also fits the experimental data well.

  13. Adsorption isotherms of hog plum (Spondias mombin L. pulp powder obtained by spray dryer

    Directory of Open Access Journals (Sweden)

    Luís Gomes de Moura Neto

    2015-05-01

    Full Text Available Food sorption isotherms are highly important to predict drying time and storage conditions of a product. Current assay evaluates the behavior of adsorption isotherms of hog plum powder obtained by spray-dryer, through mathematical models. GAB, BET, Henderson and Oswin models were adjusted to the experimental data at 25, 30, 35 and 40ºC. The BET model best adjusted to the atomized hog plum for all temperatures tested, with an error ranging between 8.45 and 11.17%. The coefficient of determination (R2 had rates higher than 0.9900 for all the adjusted models. The behavior of hog plum powder adsorption isotherms was classified as Type III.

  14. Examination of competitive lanthanide sorption onto smectites and its significance in the management of radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Galunin, Evgeny [Departament de Quimica Analitica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Alba, Maria D. [Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Cientificas - Universidad de Sevilla, Av. Americo Vespucio 49, 41092 Sevilla (Spain); Santos, Maria J. [Departamento de Quimica, Universidade Estadual de Londrina, Londrina, PR 86051-990 (Brazil); Abrao, Taufik [Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Cientificas - Universidad de Sevilla, Av. Americo Vespucio 49, 41092 Sevilla (Spain); Vidal, Miquel, E-mail: miquel.vidal@ub.edu [Departament de Quimica Analitica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2011-02-28

    The competitive effect of La and Lu (analogues of radionuclides appearing in radioactive waste) in the sorption in four smectites was examined. Sorption and desorption distribution coefficients (K{sub d}; K{sub d,des}), and desorption rates (R{sub des}) were determined from batch tests in two media: deionized water and, to consider the influence of cement leachates, 0.02 mol L{sup -1} Ca. The competitive effect was lower when high-affinity sites were available, as in the water medium at the lowest range of initial lanthanide concentration, with high K{sub d} for La and for Lu (5-63 x 10{sup 4} L kg{sup -1}). Lower K{sub d} was measured at higher initial concentrations and in the Ca medium, where Lu showed a stronger competitive effect. This was confirmed by fitting the sorption data to a two-solute Langmuir isotherm. The desorption data indicated that sorption was virtually irreversible for the scenarios with high sorption, with an excellent correlation between K{sub d} and K{sub d,des} (R{sup 2} around 0.9 for the two lanthanides). Assuming that radioactive waste is a mixture of radionuclides, and that Ca ions will be provided by the cement leachates, this would reduce the retention capacity of clay engineered barriers.

  15. Influence of temperature and macromolecular mobility on sorption of TCE on humic acid coated mineral surfaces.

    Science.gov (United States)

    Bell, Katherine Young; LeBoeuf, Eugene J

    2013-01-01

    This study demonstrates differences in sorptive capacity of volatile organic compound (VOC) trichloroethylene (TCE) onto natural organic matter (NOM) coated and uncoated mineral surfaces above and below the NOM glass transition temperature. TCE sorption isotherms for dry NOM-mineral systems below the NOM glass transition temperature (T(g)) demonstrated sorption behavior characteristic of micropore filling, with sorption capacities reduced relative to uncoated mineral matrices. Such differences were not entirely associated with differences in surface areas of the coated and uncoated mineral matrices, but were likely associated with either a blockage of pore space available to the VOC or a kinetic limitation that does not allow the VOC access to the internal porosity of the model soil within the time periods of the experiment. TCE sorption in dry NOM-mineral matrices above the T(g), however, was described in terms of sorption within a more fluid, macromolecular dissolution medium that does not hinder access to mineral surfaces. Such observations have potential important implications for modeling the fate and transport of VOCs in soils and sediment systems.

  16. Sorption performance of cysteine-modified bentonite in heavy metals uptake

    Directory of Open Access Journals (Sweden)

    SSEIN FAGHIHIAN

    2009-07-01

    Full Text Available local clay, bentonite (N-Ben, was modified by the biologically-based ligand, cysteine (Cys, through a simple sorption technique. The modified sorbent (Cys–Ben demonstrated affinity for soft and moderately soft heavy metal ions (HMI, such as Cd(II and Pb(II, probably as a result of the soft basic character of the thiol ligand side chains. The resulting modified system was effective for metal binding with capacities of 0.503 and 0.525 mmol g-1, for Pb(II and Cd(II, respectively. Comparative batch experiments were performed for removing lead and cadmium from aqueous solutions. The sorption parameters were derived from a Langmuir fit to the sorption isotherms of the studied ions. The study showed that the sorption capacity of Cys–Ben was higher than that of N-Ben for these ions. The effect of pH was examined over the range 2.0–6.0. The sorption capacities of Cys–Ben showed that this modified clay is a good sorbent for the examined heavy metal ions.

  17. STUDY OF THE STRUCTURE OF WOOD-RELATED BIOPOLYMERS BY SORPTION METHODS

    Directory of Open Access Journals (Sweden)

    Jelena Chirkova

    2009-08-01

    Full Text Available The potentialities of different vapour sorption methods are analized for the investigation of the microstructure of wood sorbents (wood, cellulose and lignin as a particular case of biopolymers. There are two important distinctions in the sorption behaviour of biopolymers from traditional rigid sorbents, namely, the dependence of the characteristics of the porous structure on the thermodynamic properties of the sorbate, and the manifestation of the sorption hysteresis over the whole region of the sorption–desorption isotherm. The reason for these distinctions is the low rigidity (low values of modulus of elasticity of biopolymers, hence, their considerable deformability under the action of sorption forces, resulting in the cleavage of interstructural bonds. This process, manifesting itself phenomenologically as swelling, depends on the activity of the sorbate and results in the appearance of porosity and a new surface. The criterion for the activity of the sorbate is close values of the solubility parameters of the polymer and the sorbate. Inert substances are adsorbed on the surface of large morphological formations and characterise the intact structure of the sorbent, while active sorbates cause the swelling of these formations and penetrate them, which enables a study of the microstructure of sorbents. In the desorption process, the cleaved bonds are restored, blocking a part of the sorbate in the polymer’s structure, which results in the appearance of sorption hysteresis, not connected directly with the porous structure of the sorbent.

  18. Influence of clay minerals on sorption and bioreduction of arsenic under anoxic conditions.

    Science.gov (United States)

    Ghorbanzadeh, Nasrin; Lakzian, Amir; Halajnia, Akram; Kabra, Akhil N; Kurade, Mayur B; Lee, Dae S; Jeon, Byong-Hun

    2015-12-01

    Adsorption of As(V) on various clay minerals including kaolinite (KGa-1), montmorillonite (SWy-1) and nontronites (NAU-1 and NAU-2), and subsequent bioreduction of sorbed As(V) to As(III) by bacterium Shewanella putrefaciens strain CN-32 were investigated. Nontronites showed relatively higher sorption capacity for As(V) primarily due to higher iron oxide content. Freundlich equation well described the sorption of As(V) on NAU-1, NAU-2 and SWy-1, while As(V) sorption isotherm with KGa-1 fitted well in the Langmuir model. The bacterium rapidly reduced 50% of dissolved As(V) to As(III) in 2 h, followed by its complete reduction (>ca. 98%) within 12 h. In contrast, sorption of As(V) to the mineral surfaces interferes with the activity of bacterium, resulting in low bioreduction of As(V) by 27% for 5 days of incubation. S. putrefaciens also promoted the reduction of Fe(III) present in the clay mineral to Fe(II). This study indicates that the sorption and subsequent bioreduction of As(V) on clay minerals can significantly influence the mobility of As(V) in subsurface environment.

  19. Simultaneous removal of copper and lead ions from a binary solution by sono-sorption process

    Energy Technology Data Exchange (ETDEWEB)

    Entezari, M.H. [Department of Chemistry, Ferdowsi University of Mashhad, 91775 Mashhad (Iran, Islamic Republic of)], E-mail: moh_entezari@yahoo.com; Soltani, T. [Department of Chemistry, Ferdowsi University of Mashhad, 91775 Mashhad (Iran, Islamic Republic of)

    2008-12-15

    The aim of this work is to compare the simultaneous sorption of copper and lead ions from a binary aqueous solution in the presence and in the absence of ultrasound. The experiments under sonication were carried out by 20-kHz apparatus. Results indicated that the removal of copper and lead ions from a binary aqueous solution was greater in the presence of ultrasound than in control method. The removal of these ions was examined by varying experimental conditions such as the amount of sorbent, contact time, and temperature. In addition, the competitive sorption of ions was considered with different concentrations of each ion under the constant total concentration. The Langmuir isotherm model fits adequately the experimental data. In point of kinetics, the second-order kinetic model describes the sorption process for both ions. It was found that more than 90% of the lead and 60% of the copper ions was removed in less than 2 min from the solution under sonication. The thermodynamic parameters such as {delta}G{sup o}, {delta}H{sup o}, and {delta}S{sup o} were determined for the sorption of Cu{sup 2+} and Pb{sup 2+} from the temperature dependence of the sorption process.

  20. Efficient sorption and reduction of U(VI) on zero-valent iron-polyaniline-graphene aerogel ternary composite.

    Science.gov (United States)

    Chen, Lili; Feng, Shaojie; Zhao, Donglin; Chen, Shaohua; Li, Feifei; Chen, Changlun

    2017-03-15

    In this work, zero-valent iron-polyaniline-graphene aerogel composite (Fe-PANI-GA) was prepared and applied in the removal of U(VI) from aqueous solutions by batch sorption experiments. The experimental results showed that the Fe-PANI-GA composite had an excellent removal capacity for the removal of U(VI) in acidic solutions. The results also showed that the maximum removal capacity of the Fe-PANI-GA toward U(VI) was 350.47mg/g at pH 5.5. The sorption kinetics data were well-described by pseudo-second-order. The sorption isotherms of U(VI) fitted well with Langmuir isotherm and exhibited better removal efficiency with the increase of temperature. The thermodynamic parameters (ΔG, ΔS, ΔH) indicated that the sorption of U(VI) on the Fe-PANI-GA was an endothermic and spontaneous process. Moreover, removal mechanisms were studied based on the results of XRD, FTIR and XPS. Both U(VI) sorption and partially reductive precipitation of U(VI) to U(IV) contributed to the removal of U(VI) on Fe-PANI-GA. Therefore, Fe-PANI-GA was an economic and effective material for the removal of uranium from nuclear waste in practical application.

  1. Sorption of the organic cation metoprolol on silica gel from its aqueous solution considering the competition of inorganic cations.

    Science.gov (United States)

    Kutzner, Susann; Schaffer, Mario; Börnick, Hilmar; Licha, Tobias; Worch, Eckhard

    2014-05-01

    Systematic batch experiments with the organic monovalent cation metoprolol as sorbate and the synthetic material silica gel as sorbent were conducted with the aim of characterizing the sorption of organic cations onto charged surfaces. Sorption isotherms for metoprolol (>99% protonated in the tested pH of around 6) in competition with mono- and divalent inorganic cations (Na(+), NH4(+), Ca(2+), and Mg(2+)) were determined in order to assess their influence on cation exchange processes and to identify the role of further sorptive interactions. The obtained sorption isotherms could be described well by an exponential function (Freundlich isotherm model) with consistent exponents (about 0.8). In general, a decreasing sorption of metoprolol with increasing concentrations in inorganic cations was observed. Competing ions of the same valence showed similar effects. A significant sorption affinity of metoprolol with ion type dependent Freundlich coefficients KF,0.77 between 234.42 and 426.58 (L/kg)(0.77) could still be observed even at very high concentrations of competing inorganic cations. Additional column experiments confirm this behavior, which suggests the existence of further relevant interactions beside cation exchange. In subsequent batch experiments, the influence of mixtures with more than one competing ion and the effect of a reduced negative surface charge at a pH below the point of zero charge (pHPZC ≈ 2.5) were also investigated. Finally, the study demonstrates that cation exchange is the most relevant but not the sole mechanism for the sorption of metoprolol on silica gel.

  2. Moisture Transport in Wood

    DEFF Research Database (Denmark)

    Astrup, T.; Hansen, K. K.; Hoffmeyer, P.

    2005-01-01

    Modelling of moisture transport in wood is of great importance as most mechanical and physical properties of wood depend on moisture content. Moisture transport in porous materials is often described by Ficks second law, but several observations indicate that this does not apply very well to wood....... Recently at the Technical University of Denmark, Department of Civil Engineering, a new model for moisture transport in wood has been developed. The model divides the transport into two phases, namely water vapour in the cell lumens and bound water in the cell walls....

  3. Moisture Transport in Wood

    DEFF Research Database (Denmark)

    Astrup, T.; Hansen, K. K.; Hoffmeyer, P.;

    2005-01-01

    Modelling of moisture transport in wood is of great importance as most mechanical and physical properties of wood depend on moisture content. Moisture transport in porous materials is often described by Ficks second law, but several observations indicate that this does not apply very well to wood....... Recently at the Technical University of Denmark, Department of Civil Engineering, a new model for moisture transport in wood has been developed. The model divides the transport into two phases, namely water vapour in the cell lumens and bound water in the cell walls....

  4. Sorption and degradation of pharmaceuticals and personal care products (PPCPs) in soils.

    Science.gov (United States)

    Yu, Yong; Liu, Yin; Wu, Laosheng

    2013-06-01

    Pharmaceuticals and personal care products (PPCPs) are one class of the most urgent emerging contaminants, which have drawn much public and scientific concern due to widespread contamination in aquatic environment. Most studies on the environmental fate and behavior of PPCPs have focused on nonsteroidal anti-inflammatory drugs. Some other compounds with high concentrations were less mentioned. In this study, sorption and degradation of five selected PPCPs, including bisphenol A (BPA), carbamazepine (CBZ), gemfibrozil (GFB), octylphenol (OP), and triclosan (TCS) have been investigated using three different soils. Sorption isotherms of all tested PPCPs in soils were well described by Freundlich equation. TCS and OP showed moderate to strong sorption, while the sorption of GFB and CBZ in soils was negligible. Degradation of PPCPs in three soils was generally fitted first-order exponential decay model, with half-lives (t 1/2) varying from 9.8 to 39.1 days. Sterilization could prolong the t 1/2 of PPCPs in soil, indicating that microbial activity played an important role in the degradation of these chemicals in soils. Degradation of PPCPs in soils was also influenced by the soil organic carbon (f oc) contents. Results from our data show that sorption to the soils varied among the different PPCPs, and their sorption affinity on soil followed the order of TCS > OP > BPA > GFB > CBZ. The degradation of the selected PPCPs in soil was influenced by the microbial activity and soil type. The poor sorption and relative persistence of CBZ suggest that it may pose a high leaching risk for groundwater contamination when recycled for irrigation.

  5. Kinetics and thermodynamics of uranium(VI) sorption on hydrous silica

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, P.N.; Choppin, G.R. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemistry and Biochemistry

    2007-07-01

    Sorption of uranyl ion, UO{sub 2}{sup 2+}, on SiO{sub 2}.{chi}H{sub 2}O (silica gel) has been investigated as a function of time, amount of silica gel (0.10-0.60g), uranium concentration (5.00 x 10{sup -5}-1.00 x 10{sup -3}M), ionic strength (0.20-1.40M NaClO{sub 4}), pH ({proportional_to} 2.0-6.0), and temperature (283-333K). Based on kinetic data, the diffusion coefficient of UO{sub 2}{sup 2+} ion was calculated to be 6.83({+-}0.22) x 10{sup -12}m{sup 2}s{sup -1} under particle diffusion-controlled conditions. The rate of sorption of uranyl ion on silica gel was determined to be 8.56({+-}0.50) x 10{sup -2}min{sup -1} at 298K, pH 1.82{+-}0.05 and 0.20M NaClO{sub 4}. The uranyl sorption data on silica gel followed the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Uranyl sorption (%) in creased with ionic strenght from 11.48{+-}0.03 (0.20M NaClO{sub 4}) to 34.81{+-}0.20 (1.40M NaClO{sub 4}) at pH 2.79{+-}0.03 using 0.10g silica gel. The sorption decreased in the presence of 1.00 x 10{sup -3} M fluoride and oxalate ions; while the presence of carbonate anion showed negligible change in uranyl sorption profile in the pH range of 2 to 6 at 0.20M NaClO{sub 4}. Temperature variation experiments showed that the sorption of uranium on silica gel had an endothermic enthalpy, which became more spontaneous at elevated temperatures. (orig.)

  6. Soil Components Affecting Phosphate Sorption Parameters of Acid Paddy Soils in Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Soil components affecting phosphate sorption parameters were studied using acid paddy soils derived from basalt, granite, sand-shale and the Pearl River Delta sediments, respectively, in Guangdong Province.For each soil, seven 2.50 g subsamples were equilibrated with 50 mL 0.02 mol L-1 (pH=7.0) of KCl containing 0, 5, 10, 15, 25, 50 and 100 ng P kg-1, respectively, in order to derive P sorption parameters (P sorption maximum, P sorption intensity factor and maximum buffer capacity) by Langmuir isotherm equation. It was shown that the main soil components influencing phosphate sorption maximum (Xm) included soil clay, pH,amorphous iron oxide (Feo) and amorphous aluminum oxide (Alo), with their effects in the order of Alo >Feo > pH > clay. Among these components, pH had a negative effect, and the others had a positive effect.Organic matter (OM) was the only soil component influencing P sorption intensity factor (K). The main components influencing maximum phosphate buffer capacity (MBC) consisted of soil clay, OM, pH, Feo and Alo, with their effects in the order of Alo > OM > pH > Feo > clay. Path analysis indicated that among the components with positive effects on maximum phosphate buffer capacity (MBC), the effect was in the order of Alo > Feo > Clay, while among the components with negative effects, OM > pH. OM played an important role in mobilizing phosphate in acid paddy soils mainly through decreasing the sorption intensity of phosphate by soil particles.

  7. Behavior of Cs in Grimsel granodiorite. Sorption on main minerals and crushed rock

    Energy Technology Data Exchange (ETDEWEB)

    Muuri, Eveliina; Ikonen, Jussi; Matara-aho, Minja; Voutilainen, Mikko; Siitari-Kauppi, Marja [Helsinki Univ. (Finland). Dept. of Chemistry; Lindberg, Antero [Geological Survey of Finland, Espoo (Finland); Holgersson, Stellan [Chalmers University of Technology, Goeteborg (Sweden). Dept. of Chemical and Biological Engineering, Nuclear Chemistry; Martin, Andrew [Nagra (National Cooperative for the Disposal of Radioactive Waste), Wettingen (Switzerland)

    2016-11-01

    In this study the sorption of cesium was investigated on four different minerals; quartz, plagioclase, potassium feldspar and biotite as well as granodiorite obtained from the Grimsel test site in Switzerland. The experiments were conducted in the presence of the weakly saline Grimsel groundwater simulant by determining the distribution coefficients using batch sorption experiments and PHREEQC-modelling across a large concentration range. In addition, the purity of the minerals was measured by XRD and the specific surface areas by BET method using krypton. The distribution coefficients of cesium were largest on biotite (0.304±0.005 m{sup 3}/kg in 10{sup -8} M). Furthermore, the sorption of cesium on quartz was found to be negligibly small in all investigated concentrations and the sorption of cesium on potassium feldspar and plagioclase showed similar behavior against a concentration isotherm with distribution coefficients of 0.0368±0.0004 m{sup 3}/kg and 0.18±0.04 m{sup 3}/kg in 10{sup -8} M. Finally, cesium sorption behavior on crushed granodiorite followed the trend of one of its most abundant mineral, plagioclase with distribution coefficient values of 0.107±0.003 m{sup 3}/kg in 10{sup -8} M. At low concentrations (<1.0.10{sup -6} M) cesium was sorbed on the frayed edge sites of biotite and once these sites are fully occupied cesium sorbs additionally to the Type II and Planar sites. As a consequence, the sorption of cesium on biotite is decreased at concentrations >1.0.10{sup -6} M. Secondly cesium sorption on potassium feldspar and plagioclase showed similar non-linear behavior with varying concentration. The results were used to assist the interpretation of cesium diffusion process in the 2.5 year in-situ experiment carried out in the underground laboratory at Grimsel test site in Switzerland (2007-2009).

  8. Prediction of the sorption capacities and affinities of organic chemicals by XAD-7.

    Science.gov (United States)

    Yang, Kun; Qi, Long; Wei, Wei; Wu, Wenhao; Lin, Daohui

    2016-01-01

    Macro-porous resins are widely used as adsorbents for the treatment of organic contaminants in wastewater and for the pre-concentration of organic solutes from water. However, the sorption mechanisms for organic contaminants on such adsorbents have not been systematically investigated so far. Therefore, in this study, the sorption capacities and affinities of 24 organic chemicals by XAD-7 were investigated and the experimentally obtained sorption isotherms were fitted to the Dubinin-Ashtakhov model. Linear positive correlations were observed between the sorption capacities and the solubilities (SW) of the chemicals in water or octanol and between the sorption affinities and the solvatochromic parameters of the chemicals, indicating that the sorption of various organic compounds by XAD-7 occurred by non-linear partitioning into XAD-7, rather than by adsorption on XAD-7 surfaces. Both specific interactions (i.e., hydrogen-bonding interactions) as well as nonspecific interactions were considered to be responsible for the non-linear partitioning. The correlation equations obtained in this study allow the prediction of non-linear partitioning using well-known chemical parameters, namely SW, octanol-water partition coefficients (KOW), and the hydrogen-bonding donor parameter (αm). The effect of pH on the sorption of ionizable organic compounds (IOCs) could also be predicted by combining the correlation equations with additional equations developed from the estimation of IOC dissociation rates. The prediction equations developed in this study and the proposed non-linear partition mechanism shed new light on the selective removal and pre-concentration of organic solutes from water and on the regeneration of exhausted XAD-7 using solvent extraction.

  9. p-Nitrophenol, phenol and aniline sorption by organo-clays.

    Science.gov (United States)

    Ko, Chun Han; Fan, Chihhao; Chiang, Po Neng; Wang, Ming Kuang; Lin, Kuo Chuan

    2007-10-22

    The aims of this study were to make use of organo-clays (i.e., Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A), to remove p-nitrophenol, phenol and aniline of organic pollutants. The organo-clays were characterized by X-ray diffraction (XRD). Sorption isotherm, kinetic and pH effect of p-nitrophenol, phenol and aniline sorbed by four organo-clays were evaluated. The d-spacings (001) of the XRD peak of Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A are 1.98, 2.76, 1.93 and 2.64 nm, respectively. The d(001)-spacings of XRD indicated that these p-nitropheno, phenol and aniline could penetrate into the interlayer of clays and expand the d(001)-spacings. The linear sorption isotherm of constant partition was employed to describe the sorption isotherms of phenols sorbed by organo-clays through hydrophobic-hydrophobic chemical reactions. The parabolic diffusion and power-function of kinetic models were employed to describe properly the kinetic experiments. The rate limiting step of the p-nitrophenol sorption reactions on organo-clays were diffusion-controlled processes (i.e., 15A, 30B, 93A) and chemical-controlled process for 10A organo-clays. The pre-exponential factor of the p-nitrophenol sorbed by four organo-clays showed the trend as follows: 10A> 30B> 93A> 15A. The efficiency of these organo-clays in removing phenol compounds in water treatments merit further study.

  10. Sorption of Ni(II) ions from aqueous solution by Lewatit cation-exchange resin.

    Science.gov (United States)

    Dizge, Nadir; Keskinler, Bülent; Barlas, Hulusi

    2009-08-15

    Ion-exchange is an alternative process for uptake of heavy metals from aqueous solutions. In the present study, the sorption of nickel(II) ions from aqueous solution was investigated by using Lewatit MonoPlus SP 112 (strongly acidic, macroporous cation-exchange resin) in a batch adsorption system as a function of pH (2.0-8.0), initial nickel concentration (50-200 mg/L), resin dosage (0.5-2.0 g/L), contact time (0.5-3h), and temperatures (298-318K). The data were analyzed on the basis of Lagergren pseudo-first order, pseudo-second order (Types 1-5), Elovich and external, Weber-Morris intraparticle, pore-surface mass diffusion models. The experimental data showed that the maximum pH for efficient sorption of nickel(II) was 6.0. At the optimal conditions, nickel(II) ions sorption on the resin was decreased when the initial metal concentration increased. The results indicated that the resin dosage strongly affected the amount of nickel(II) ions removed from aqueous solution. The adsorption process was very fast due to 80% of nickel(II) sorption was occurred within 30 min and equilibrium was reached at about 90 min. Freundlich and Langmuir adsorption isotherm models were used for sorption equilibrium data and the maximum adsorption capacity (171 mg/g) of Lewatit MonoPlus SP 112 was obtained from Langmuir isotherm. The thermodynamic parameters (DeltaG degrees, free energy change; DeltaS degrees, enthalpy change; and DeltaH degrees, entropy change) for sorption of nickel(II) ions were evaluated. The rise in temperature caused a partly increase in the value of the equilibrium constant (K(c)) for the sorption of nickel(II) ions. Moreover, column flow adsorption study was also studied. Breakthrough curves were obtained from column flow studies by using both synthetic solution and rinsing bath water of filter industry. The column regeneration was carried out for two sorption-desorption cycles. The eluant used for regeneration of the cation-exchange resin was 7% (w/w) HCl. The

  11. Sorption of lindane to river biofilms, suspended particles and sediments in the presence and absence of Cr(VI) and As(V)

    Science.gov (United States)

    Guo, Z.; Dong, D.; Hua, X.; Lan, X.; Liang, D.

    2013-12-01

    Few study has focused on the effects of Cr(VI) and As(V) which are often in the form of anionic groups in natural aquatic environment on the sorption of dissolved hydrophobic organic pollutants (HOPs) onto natural solid materials from water. In this study, we compared the sorption thermodynamics of lindene as a model dissolved HOP on biofilms, suspended particles and surface sediments collected from the same river in the presence and absence of Cr(VI) and As(V). Visual MINTEQ (version 3.0) was applied to calculate Cr(VI) and As(V) species in the sorption system. CrO42- (89%) was the main Cr(VI) species and HAsO42- (78%) and H2AsO4- (22%) were the As(V) species. Compared with Freundlich and the dual reactive domain model, linear model gave a better fit for the lindane sorption isotherms on the biofilms, particles and sediments (Fig.1). For the lindane sorption on the biofilms, the linear model distribution coefficient (KL) were reduced by 48.0% and 47.6% in the presence of Cr(VI) and As(V), respectively; For that on the suspended particles, KL were reduced by 6.2% and 10.8%, respectively; For the sediments, KL were reduced by 30.2% and 34.5%, respectively. In general, the presence of Cr(VI) and As(V) inhibited lindane sorption onto the three solids and inhibition level decreased in the order biofilms > sediments > particles. In contrast to the promotion of metal cations on the dissolved HOPs sorption onto natural solid materials, anionic Cr(VI) and As(V) groups suppressed the sorption. This indicated that anionic Cr(VI) and As(V) groups might occupy some sorption sites on solids and then occurred competitive sorption with lindane. Taking account of the errors in experiment, effects on the sorption between Cr(VI) and As(V) has no significant difference. This shown that the type of metal has little effect on the HOPs sorption onto natural solids. This result was consistent with that in other related studis. In addition, we inferred that the differences of component

  12. The sorption characteristics of mercury as affected by organic matter content and/or soil properties

    Science.gov (United States)

    Šípková, Adéla; Šillerová, Hana; Száková, Jiřina

    2014-05-01

    The determination and description of the mercury sorption extend on soil is significant for potential environmental toxic effects. The aim of this study was to assess the effectiveness of mercury sorption at different soil samples and vermicomposts. Mercury interactions with soil organic matter were studied using three soils with different physical-chemical properties - fluvisol, cambisol, and chernozem. Moreover, three different vermicomposts based on various bio-waste materials with high organic matter content were prepared in special fermentors. First was a digestate, second was represented by a mixture of bio-waste from housing estate and woodchips, and third was a garden bio-waste. In the case of vermicompost, the fractionation of organic matter was executed primarily using the resin SuperliteTM DAX-8. Therefore, the representation of individual fractions (humic acid, fulvic acid, hydrophilic compounds, and hydrophobic neutral organic matter) was known. The kinetics of mercury sorption onto materials of interest was studied by static sorption experiments. Samples were exposed to the solution with known Hg concentration of 12 mg kg-1 for the time from 10 minutes to 24 hours. Mercury content in the solutions was measured by the inductively coupled plasma mass spectrometry (ICP-MS). Based on this data, the optimum conditions for following sorption experiments were chosen. Subsequently, the batch sorption tests for all soil types and vermicomposts were performed in solution containing variable mercury concentrations between 1 and 12 mg kg-1. Equilibrium concentration values measured in the solution after sorption and calculated mercury content per kilogram of the soil or the vermi-compost were plotted. Two basic models of sorption isotherm - Langmuir and Freundlich, were used for the evaluation of the mercury sorption properties. The results showed that the best sorption properties from studied soil were identified in chernozem with highest cation exchange

  13. An unusual H2 sorption mechanism in PCN-14: insights from molecular simulation.

    Science.gov (United States)

    Pham, Tony; Forrest, Katherine A; Space, Brian

    2016-08-01

    Simulations of H2 sorption were performed in PCN-14, a metal-organic framework (MOF) that consists of Cu(2+) ions coordinated to 5,5'-(9,10-anthracenediyl)diisophthalate (adip) linkers. This MOF displays an excess H2 uptake of 2.70 wt% at 77 K and 1.0 atm and an initial H2Qst value of 8.6 kJ mol(-1) according to previous experimental measurements. The experimental H2 sorption isotherms and Qst values in PCN-14 were reproduced in simulations using well-known H2 potentials that have been widely used for MOF-H2 theoretical studies. H2 sorption in PCN-14 was dominated by repulsion/dispersion energetics; this allowed the experimental observables to be reproduced by a model that includes only Lennard-Jones parameters. The most energetically favorable H2 sorption site in PCN-14 corresponds to sorption within a small cage that is enclosed by three [Cu2(O2CR)4] units and three adip linkers. The anthracenyl rings of the adip linkers represent the secondary sorption sites within the MOF. In contrast to expectations, sorption of H2 onto the Cu(2+) ions of the copper paddlewheels was not observed within the simulations at low loading. The simulations revealed that the open-metal sites in PCN-14 were occupied at high loading. Control simulations of H2 sorption in PCN-14 for different cases in which the partial positive charge of one of the paddlewheel Cu(2+) ions was increased relative to the other revealed that sorption onto the open-metal sites can be captured if there is a very high positive charge on the metal. Otherwise, the calculated partial charge for the Cu(2+) ions in PCN-14 in this work was not high enough in magnitude to facilitate strong H2-metal interactions in simulation. This study shows the power of using molecular simulations to elucidate an unusual H2 sorption behavior in a MOF.

  14. Deviations from sorption linearity on soils of polar and nonpolar organic compounds at low relative concentrations

    Science.gov (United States)

    Chiou, C.T.; Kile, D.E.

    1998-01-01

    A series of single-solute and binary-solute sorption data have been obtained on representative samples of polar compounds (substituted ureas and phenolic compounds) and of nonpolar compounds (e.g., EDB and TCE) on a peat soil and a mineral (Woodburn) soil; the data extend to low relative solute concentrations (C(e)/S(w)). At relatively low C(e)/S(w), both the nonpolar and the polar solutes exhibit nonlinear sorption. The sorption nonlinearity approaches apparent saturation at about C(e)/S(w) = 0.010-0.015 for the nonpolar solutes and at about C(e)/S(w) = 0.10-0.13 for the polar solutes; above these C(e)/S(w) regions, the isotherms are practically linear. The nonlinear sorption capacities are greater for polar solutes than for nonpolar solutes and the peat soil shows a greater effect than the Woodburn soil. The small nonlinear sorption capacity for a nonpolar solute is suppressed indiscriminately by either a nonpolar or a polar cosolute at relatively low C(e)/S(w) of the cosolute. By contrast, the abilities of different cosolutes to suppress the nonlinear capacity of a nominal polar solute differ drastically. For polar solutes, a nonpolar cosolute exhibits a limited suppression even at high cosolute C(e)/S(w); effective suppression occurs when the cosolute is relatively polar and at various C(e)/S(w). These differences suggest that more than a single mechanism is required to account for the nonlinear sorption of both nonpolar and polar compounds at low C(e)/S(w). Mechanistic processes consistent with these observations and with soil surface areas are discussed along with other suggested models. Some important consequences of the nonlinear competitive sorption to the behavior of contaminants in natural systems are discussed.A number of conceptual models was postulated to account for the nonlinear solute sorption on soils of significant soil organic matter. A series of single-solute and binary-route sorption data was obtained representing samples of polar compounds of

  15. Isothermal and Near Isothermal Processing of Titanium Alloys

    Directory of Open Access Journals (Sweden)

    T. Raghu

    2011-01-01

    Full Text Available Isothermal and near isothermal forging are specialized metal processing techniques which are used for producing critical aeroengine components out of advanced materials such as titanium alloys. The process can be used to produce net / near net shape components leading to optimum utilization of materials. As titanium alloys are highly sensitive to temperature and strain rate, these processes help to deform them under slow and controlled strain rates.  Further, these processes can be combined with other conventional and non conventional metal forming processes to refine the microstructure. For example, multiaxial isothermal forging coupled with pack rolling can be used to produce thin sheets out of titanium alloys with submicron grain size. The refined structure exhibits superplastic characteristics at low temperatures and high strain rates. This lower temperature superplastic characteristic can be exploited to establish technologies for producing various components. The paper throws light on the capabilities of isothermal forging process and its variants.Defence Science Journal, 2011, 61(1, pp.72-80, DOI:http://dx.doi.org/10.14429/dsj.61.321

  16. Sorption Enhanced Reaction Process (SERP) for production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Anand, M.; Hufton, J.; Mayorga, S. [Air Products and Chemicals, Inc., Allentown, PA (United States)] [and others

    1996-10-01

    Sorption Enhanced Reaction Process (SERP) is a novel process that is being developed for the production of lower cost hydrogen by steam-methane reforming (SMR). In this process the reaction of methane with steam is carried out in the presence of an admixture of a catalyst and a selective adsorbent for carbon dioxide. The key consequences of SERP are: (i) reformation reaction is carried out at a significantly lower temperature (300-500{degrees}C) than that in a conventional SMR reactor (800-1100{degrees}C), while achieving the same conversion of methane to hydrogen, (ii) the product hydrogen is obtained at reactor pressure (200-400 psig) and at 98+% purity directly from the reactor (compared to only 70-75% H{sub 2} from conventional SMR reactor), (iii) downstream hydrogen purification step is either eliminated or significantly reduced in size. The first phase of the program has focused on the development of a sorbent for CO{sub 2} which has (a) reversible CO{sub 2} capacity >0.3 mmol/g at low partial pressures of CO{sub 2} (0.1 - 1.0 atm) in the presence of excess steam (pH{sub 2}O/pCO{sub 2}>20) at 400-500{degrees}C and (b) fast sorption-desorption kinetics for CO{sub 2}, at 400-500{degrees}C. Several families of supported sorbents have been identified that meet the target CO{sub 2} capacity. A few of these sorbents have been tested under repeated sorption/desorption cycles and extended exposure to high pressure steam at 400-500{degrees}C. One sorbent has been scaled up to larger quantities (2-3 kg) and tested in the laboratory process equipment for sorption and desorption kinetics of CO{sub 2}. The CO{sub 2}, sorption and desorption kinetics are desirably fast. This was a critical path item for the first phase of the program and now has been successfully demonstrated. A reactor has been designed that will allow nearly isothermal operation for SERP-SMR. This reactor was integrated into an overall process flow diagram for the SERP-SMR process.

  17. Mechanistic understanding and performance of biosorption of metal ions by grapefruit peel using FTIR spectroscopy, kinetics and adsorption isotherms modeling, alkali and alkaline metal displacement and EDX analysis

    Science.gov (United States)

    The performance and mechanism of the sorptive removal of Ni2+ and Zn2+ from aqueous solution using grapefruit peel (GFP) as a new sorbent was investigated. The sorption process was fast, equilibrium was established in 60 min. The equilibrium process was described well by the Langmuir isotherm model,...

  18. Sorption and Transport of Ranitidine in Natural Soils

    Science.gov (United States)

    Gaynor, A. J.; Vulava, V. M.

    2013-12-01

    Increasing levels of pharmaceuticals and their degradants are being discovered in natural water systems all over the world. These chemicals are reported to be discharged from wastewater treatment plants, sewage overflow, and leaking septic tanks. Ranitidine is an example of one such pharmaceutical chemical found in municipal drinking water, streams, and streambed sediments. It is a histamine H2-receptor antagonist, which inhibits the production of stomach acid and is commonly used to treat peptic ulcers and gastro esophageal reflux disease. Ranitidine is a complex organic compound; it is acidic, highly polar, and has two pKa values of approximately 8.2 and 2.7 because of the amine functional groups. When administered orally 25 - 30% of unchanged ranitidine has been shown to expel through urine. The objective of this research is to establish sorption and transport patterns of ranitidine in natural soils and to determine which soil properties influence these patterns the most. Laboratory experiments were preformed on A-horizon and B-horizon soil samples collected from the relatively undisturbed Francis Marion National Forest, a managed forest near Charleston, SC. The soils were characterized for chemical and physical properties: ranges of clay content = 6-20%, total organic content = 1-8%, and pH = 3.6-4.9. Kinetic reaction rates and equilibrium sorption isotherms were measured using batch experiments, whereas column experiments were used to quantify transport behavior. The reaction rates were -0.22/day and -0.33/day for organic-rich and clay-rich soils, respectively. The kinetic reaction rates were used to determine equilibration times for further equilibrium batch reactor experiments, which have soil solutions spiked with concentrations of ranitidine ranging from 0.1 mg/L to 100 mg/L. The concentration remaining in solution (C, mg/L) was plotted against the concentration in the soil (q, mg/kg) to create sorption isotherms. Ranitidine was more strongly sorbed to B

  19. Combination moisture and hydrogen getter

    Science.gov (United States)

    Harrah, L.A.; Mead, K.E.; Smith, H.M.

    1983-09-20

    A combination moisture and hydrogen getter comprises (a) a moisture getter comprising a readily oxidizable metal; and (b) a hydrogen getter comprising (1) a solid acetylenic compound and (2) a hydrogenation catalyst. A method of scavenging moisture from a closed container uses the combination moisture and hydrogen getter to irreversibly chemically reduce the moisture and chemically bind the resultant hydrogen.

  20. Hemp yarn reinforced composites – III. Moisture content and dimensional changes

    DEFF Research Database (Denmark)

    Madsen, Bo; Hoffmeyer, Preben; Lilholt, Hans

    2012-01-01

    Based on a comprehensive set of experimental data it is demonstrated that the moisture properties of aligned hemp fibre yarn/thermoplastic matrix composites are showing low moisture sorption capacity and low dimensional changes. Using a reference humidity of 65% RH, and a common span of ambient...... content of the composites is shown to be well predicted by a mixtures relationship using the measured moisture contents of the constituents. The dimensional changes of the composites are well predicted by micromechanical models of the transverse and axial hygral strains....

  1. Sorption of different phenol derivatives on functionalized macroporous nanocomposite of poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate and acid modified bentonite

    Directory of Open Access Journals (Sweden)

    Marinović Sanja R.

    2014-01-01

    Full Text Available Macroporous nanocomposite of poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate and acid modified bentonite was prepared by radical suspension copolymerization. Nanocomposite was functionalized with diethylene triamine (deta, by ring-opening reaction of the pendant epoxy groups. Functionalization was performed in order to enable phenol derivatives sorption. This new, not sufficiently investigated material, with developed porous structure was denoted CP-SA-deta. In this study, the influence of temperature on 4-nitrophenol (4NP sorption on CP-SA-deta was investigated. The chemisorption was estimated as dominant process since activation energy of sorption of 4NP of 54.8 kJ mol-1 was obtained. After determining the optimal sorption conditions for 4NP, the sorption of 2-nitrophenol (2NP and 2-chloro 4-nitrophenol (2Cl4NP on CP-SA-deta was investigated with respect to pH, initial concentration and contact time. The 2NP sorption was seldom tested, while according to our knowledge, the 2Cl4NP sorption was not investigated. The isotherm data were best fitted with Langmuir model, while the sorption dynamics obeyed the pseudo-second-order kinetic model for all derivatives. [Projekat Ministarstva nauke Republike Srbije, br. III 45001 i br. III 43009

  2. Heterogeneous carbonaceous matter in sedimentary rock lithocomponents causes significant trichloroethylene (TCE) sorption in a low organic carbon content aquifer/aquitard system

    Science.gov (United States)

    Choung, Sungwook; Zimmerman, Lisa R.; Allen-King, Richelle M.; Ligouis, Bertrand; Feenstra, Stanley

    2014-10-01

    This study evaluated the effects of heterogeneous thermally altered carbonaceous matter (CM) on trichloroethylene (TCE) sorption for a low fraction organic carbon content (foc) alluvial sedimentary aquifer and aquitard system (foc = 0.046-0.105%). The equilibrium TCE sorption isotherms were highly nonlinear with Freundlich exponents of 0.46-0.58. Kerogen + black carbon was the dominant CM fraction extracted from the sediments and accounted for > 60% and 99% of the total in the sands and silt, respectively. Organic petrological examination determined that the kerogen included abundant amorphous organic matter (bituminite), likely of marine origin. The dark calcareous siltstone exhibited the greatest TCE sorption among aquifer lithocomponents and accounted for most sorption in the aquifer. The results suggest that the source of the thermally altered CM, which causes nonlinear sorption, was derived from parent Paleozoic marine carbonate rocks that outcrop throughout much of New York State. A synthetic aquifer-aquitard unit system (10% aquitard) was used to illustrate the effect of the observed nonlinear sorption on mass storage potential at equilibrium. The calculation showed that > 80% of TCE mass contained in the aquifer was sorbed on the aquifer sediment at aqueous concentration < 1000 μg L- 1. These results show that sorption is likely a significant contributor to the persistence of a TCE groundwater plume in the aquifer studied. It is implied that sorption may similarly contribute to TCE persistence in other glacial alluvial aquifers with similar geologic characteristics, i.e., comprised of sedimentary rock lithocomponents that contain thermally altered CM.

  3. MEASUREMENT AND MODELLING OF SORPTION EQUILIBRIUM CURVE OF WATER ON PA6, PP, HDPE AND PVC BY USING FLORY-HUGGINS MODEL

    Directory of Open Access Journals (Sweden)

    Suherman Suherman

    2012-02-01

    Full Text Available The sorption of water on granular polyamide-6 (PA6, granular polypropylene (PP, and powdery high density polyethylene (HDPE and powdery polyvinyl chloride (PVC were measured using a gravimetric method in a magnetic suspension balance (MSB. The Flory-Huggins model was successfully applied on the sorption equilibrium curve of all investigated polymers. The influence of temperature is low. The value of Flory-Huggins parameters(c of PA6, PVC, PP and HDPE were 1.8, 5.8, 6.3, and 8.1, respectively. The water in PA6 is mainly bound moisture, while in PP, HDPE and PVC it is mainly surface moisture.

  4. Equilíbrio higroscópico da palma forrageira: relação com a umidade ótima para fermentação sólida Hygroscopic equilibrium of the cactus pear: relation with the optimum moisture for the solid fermentation

    Directory of Open Access Journals (Sweden)

    Lúcia de F. Araújo

    2005-09-01

    Full Text Available No estudo do processo de enriquecimento protéico da palma forrageira (Opuntia ficus-indica Mill através da levedura Saccharomyces cerevisiae em meio semi-sólido, a atividade de água é uma das variáveis que mais afetam não apenas o processo fermentativo mas, também, o armazenamento desse enriquecido; desta forma, o presente trabalho foi realizado com o objetivo de se obter isotermas de dessorção da cactácea palma forrageira, nas temperaturas usuais dos processos das fermentações, 30, 35 e 40 oC, de modo a correlacionar atividade de água e umidade. As isotermas obtidas foram analisadas mediante os modelos de GAB e BET sendo que, em geral, o modelo de GAB foi o que melhor se ajustou aos dados experimentais. A partir das isotermas obtidas, encontraram-se as faixas de umidades adequadas para obtenção das atividades de água recomendadas para o processo fermentativo e durante o armazenamento do enriquecido.In the study of the protein enrichment process of the cactus pear (Opuntia ficus-indica Mill through the yeast Saccharomyces cerevisiae in semi-solid state fermentation, the water activity is one of the variables that most affects the fermentation process as well as the storage. The present work had the objective of obtaining isotherms of sorption of the cactus pear, in the usual temperatures of the fermentations processes, 30, 35 and 40 oC, in order to correlate water activity and moisture content. The obtained isotherms were analyzed by the GAB and BET models, the GAB model being, in general, the one that adjusted better to the experimental data. The isotherms allowed to find appropriate moisture content to obtain the water activities recommended for the fermentation process as well as during the storage of this enriched product.

  5. Sorption of chromium in soils of the Cerrado Goias, Brazil

    Directory of Open Access Journals (Sweden)

    Welershon José de Castro

    2010-08-01

    Full Text Available Land application of tannery sludge, which usually contain high levels of chromium, and considerable amounts of organic matter, macronutrients and micronutrients may contribute to the improvement of soil fertility and plant nutrition, and constitutes a form of disposal residue in the environment. The objective of this work was to determine the sorption isotherms of metal chromium (Cr+3 in a Ultisol, Oxisol Typic Acrustox, Quartzipsamment and Kandic Oxisol, identify soil classes that are prone to chromium mobility, and characterize the potential of agricultural soils of Goiás that are subject to groundwater contamination by the potentially toxic metal. For the establishment of sorption isotherms, solutions were prepared at 1:10 in volume. Air dried samples of 5.0 cm3 of each class of soil were placed in triplicates in beakers of 250.0 cm3. A solution containing 50.0 cm3 of the potentially toxic metal was added to solution. The solutions were prepared in CaCl2.(2H2O (0.01 mol.L-1 as electrolyte support and employing the basic chromium sulphate as a source of metal. Adjustments were made to the polynomial regression between the concentrations of potentially toxic levels of metal contaminants in the solution depending on the concentration of metal in the filtered solution after equilibrium. The Quartzipsamment showed lower retention compared to other classes of soils. Therefore it is more vulnerable to groundwater contamination if industrial wastes containing trivalent chromium are used as fertilizer.

  6. Sorption of dissolved organic matter and its effects on the atrazine sorption on soils

    Institute of Scientific and Technical Information of China (English)

    LING Wan-ting; WANG Hai-zhen; XU Jian-ming; GAO Yan-zheng

    2005-01-01

    The dissolved organic matter(DOM), water soluble organic matter derived from sewage sludge was separated into hydrophobic fraction(Ho) and hydrophilic fraction(Hi). The sorption of DOM and its fractions on soils and the effects of DOM sorption on a nonionic pesticide(atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trazine)) distribution between soil and water were investigated using a batch equilibrium technique. The total DOM sorption on soils described by the Langmuir equation reached saturation as the DOMconcentration increased. The sorption of Ho fit the Freundlich model. In contrast, a negative retention evidently occurred as adding Hi at higher level in tested soils. The sorption of Ho dominated the total DOM sorption and the release of soil organic matter(SOM). Effects of DOM on the atrazine sorption by soils were DOM-concentration dependent and dominated by the interaction of atrazine, DOM, and soil solids. Generally, the presence of DOM with lower concentration promoted atrazine sorption on soils, namely the apparent partitioning constant( K; ) for atrazine sorption in the presence of DOM was larger than the distribution constant ( Kd ) without DOM; whereas the presence of DOM with higher concentration inhibited atrazine sorption(i. e., K; < Kd ) . The overall effects of DOM on atrazine sorption in soils might be related to the DOM sorption and the release of soil intrinsic organic matter into aqueous solution. The sorption of Ho on soils promoted the atrazine sorption on soil, while the release of SOM by Hi and the competitive sorption between Hi and atrazine on soil surface led to a decrease of atrazine sorption. Information provided in this work may contribute to a better understanding of the DOM sorption and its impacts on the contaminant soil-water distribution.

  7. Indium Sorption to Iron Oxides

    Science.gov (United States)

    White, S. J.; Sacco, S. A.; Hemond, H.; Hussain, F. A.; Runkel, R. L.; Walton-Day, K. E.; Kimball, B. A.; Shine, J. P.

    2014-12-01

    Indium is an increasingly important metal in semiconductors and electronics, and its use is growing rapidly as a semiconductive coating (as indium tin oxide) for liquid crystal displays (LCDs) and flat panel displays. It also has uses in important energy technologies such as light emitting diodes (LEDs) and photovoltaic cells. Despite its rapid increase in use, very little is known about the environmental behavior of indium, and concerns are being raised over the potential health effects of this emerging metal contaminant. One source of indium to the environment is acid mine drainage from the mining of lead, zinc, and copper sulfides. In our previous studies of a stream in Colorado influenced by acid mine drainage from lead and zinc mining activities, indium concentrations were found to be 10,000 times those found in uncontaminated rivers. However, the speciation and mobility of indium could not be reliably modeled because sorption constants to environmental sorbents have not been determined. In this study, we generate sorption constants for indium to ferrihydrite in the laboratory over a range of pHs, sorbent to sorbate ratios, and ionic strengths. Ferrihydrite is one of the most important sorbents in natural systems, and sorption to amorphous iron oxides such as ferrihydrite is thought to be one of the main removal mechanisms of metals from the dissolved phase in aqueous environments. Because of its relatively low solubility, we also find that indium hydroxide precipitation can dominate indium's partitioning at micromolar concentrations of indium. This precipitation may be important in describing indium's behavior in our study stream in Colorado, where modeling sorption to iron-oxides does not explain the complete removal of indium from the dissolved phase when the pH of the system is artificially raised to above 8. This study contributes much-needed data about indium's aqueous behavior, in order to better understand its fate, transport, and impacts in the

  8. Isothermal Dendritic Growth Experiment Video

    Science.gov (United States)

    1997-01-01

    This video, captured during the Isothermal Dendritic Growth Experiment (IDGE) flown on STS-87 as a part of the fourth United States Microgravity payload, shows the growth of a dendrite, and the surface solidification that occurred on the front and back windows of the growth chamber. Dendrites are tiny, tree like structures that form as metals solidify.

  9. Isothermal Amplification of Insect DNA

    Science.gov (United States)

    The loop-mediated isothermal amplification of DNA (LAMP) method can amplify a target DNA sequence at a constant temperature in about one hour. LAMP has broad application in agriculture and medicine because of the need for rapid and inexpensive diagnoses. LAMP eliminates the need for temperature cycl...

  10. Covariant description of isothermic surfaces

    CERN Document Server

    Tafel, Jacek

    2014-01-01

    We present a covariant formulation of the Gauss-Weingarten equations and the Gauss-Mainardi-Codazzi equations for surfaces in 3-dimensional curved spaces. We derive a coordinate invariant condition on the first and second fundamental form which is necessary and sufficient for the surface to be isothermic.

  11. BINDING ISOTHERMS SURFACTANT-PROTEINS

    Directory of Open Access Journals (Sweden)

    Elena Irina Moater

    2011-12-01

    Full Text Available The interactions between surfactants and proteins shows some similarities with interactions between surfactants and polymers, but the hydrophobic amphoteric nature of proteins and their secondary and tertiary structure components make them different from conventional polymer systems. Many studies from the past about surfactant - proteins bonding used the dialysis techniques. Other techniques used to determine the binding isotherm, included ultrafiltration, ultracentrifugation, potentiometry, ion-selective electrode method and surface tension. High affinity isotherms which are typical of an anionic surfactant - protein bonding, exhibit an initial increase steep followed by a slow growth region and then a vertical growth above a certain concentration. This isotherm is typical of ionic surfactant to protein binding. Often the high affinity initial bond appears at very low concentrations of surfactant and therefore in some protein-surfactant systems, the exact shape of the isotherm in this region may be missing. The surfactant - protein binding is influenced by a number of variables such as the nature and chain length of surfactant, pH, ionic strength, temperature, nature of this protein and additives.

  12. Effect of pyrolysis temperature on polycyclic aromatic hydrocarbons toxicity and sorption behaviour of biochars prepared by pyrolysis of paper mill effluent treatment plant sludge.

    Science.gov (United States)

    Devi, Parmila; Saroha, Anil K

    2015-09-01

    The polycyclic aromatic hydrocarbons (PAHs) toxicity and sorption behaviour of biochars prepared from pyrolysis of paper mill effluent treatment plant (ETP) sludge in temperature range 200-700 °C was studied. The sorption behaviour was found to depend on the degree of carbonization where the fractions of carbonized and uncarbonized organic content in the biochar act as an adsorption media and partition media, respectively. The sorption and partition fractions were quantified by isotherm separation method and isotherm parameters were correlated with biochar properties (aromaticity, polarity, surface area, pore volume and ash content). The risk assessment for the 16 priority EPA PAHs present in the biochar matrix was performed and it was found that the concentrations of the PAHs in the biochar were within the permissible limits prescribed by US EPA (except BC400 and BC500 for high molecular weight PAHs).

  13. Investigating H₂ Sorption in a Fluorinated Metal-Organic Framework with Small Pores Through Molecular Simulation and Inelastic Neutron Scattering.

    Science.gov (United States)

    Forrest, Katherine A; Pham, Tony; Georgiev, Peter A; Pinzan, Florian; Cioce, Christian R; Unruh, Tobias; Eckert, Juergen; Space, Brian

    2015-07-07

    Simulations of H2 sorption were performed in a metal-organic framework (MOF) consisting of Zn(2+) ions coordinated to 1,2,4-triazole and tetrafluoroterephthalate ligands (denoted [Zn(trz)(tftph)] in this work). The simulated H2 sorption isotherms reported in this work are consistent with the experimental data for the state points considered. The experimental H2 isosteric heat of adsorption (Qst) values for this MOF are approximately 8.0 kJ mol(-1) for the considered loading range, which is in the proximity of those determined from simulation. The experimental inelastic neutron scattering (INS) spectra for H2 in [Zn(trz)(tftph)] reveal at least two peaks that occur at low energies, which corresponds to high barriers to rotation for the respective sites. The most favorable sorption site in the MOF was identified from the simulations as sorption in the vicinity of a metal-coordinated H2O molecule, an exposed fluorine atom, and a carboxylate oxygen atom in a confined region in the framework. Secondary sorption was observed between the fluorine atoms of adjacent tetrafluoroterephthalate ligands. The H2 molecule at the primary sorption site in [Zn(trz)(tftph)] exhibits a rotational barrier that exceeds that for most neutral MOFs with open-metal sites according to an empirical phenomenological model, and this was further validated by calculating the rotational potential energy surface for H2 at this site.

  14. Enantioselective sorption of the chiral fungicide metalaxyl on soil from non-racemic aqueous solutions: Environmental implications.

    Science.gov (United States)

    Celis, Rafael; Gámiz, Beatriz; Facenda, Gracia; Hermosín, María C

    2015-12-30

    Mechanisms governing the enantioselectivity of the processes that determine the behavior of chiral pollutants in the environment need to be better understood. Understanding these mechanisms should help improve predictions of the hazards and risks chiral compounds can pose to people and the environment. We report the results of batch sorption experiments indicating that the sorption of the chiral fungicide metalaxyl on soil from non-racemic initial solutions was enantioselective. While from a racemic initial solution the two enantiomers of metalaxyl were sorbed on the soil to the same extent, increasing the fraction of R-enantiomer in the initial solution led to enhanced sorption of this enantiomer and to reduced sorption of the S-enantiomer. Considering the shape of the sorption isotherms (S-type) and the sorption behavior of model sorbents, we attributed this effect to molecular interactions between metalaxyl enantiomer species at the sorbed state, where R-R metalaxyl interactions appeared to be more favorable than R-S metalaxyl interactions. We discuss important environmental implications of the proposed mechanism, such as those related to the fact that the biological degradation of metalaxyl is known to be an enantioselective process that can yield non-racemic residues in soils shortly after application of the fungicide as a racemic mixture. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Multiparametric investigation of competitive and noncompetitive sorption characteristics of SMP fractions (carbohydrate and protein) on activated carbon.

    Science.gov (United States)

    Dizge, Nadir; Tansel, Berrin

    2011-01-30

    Sorption characteristics of soluble microbial products (SMPs) as carbohydrate and protein on activated carbon were investigated. Batch experiments were conducted to evaluate the sorption kinetics and the equilibrium conditions. The parameters studied included initial SMP concentration (50-200mg/L), activated carbon dosage (0.25-50 g/L), contact time (0.02-4h), particle size of activated carbon used (5-75 μm, 75-850 μm, and 850-1000 μm), and presence of one or both SMP fractions. The equilibrium sorption of carbohydrate and protein were significantly affected by the presence of the second SMP fraction in the solutions. Adsorption isotherms were expressed by the Langmuir and Freundlich models. The adsorption rates under noncompetitive and competitive conditions were analyzed with kinetics-based Lagergren pseudo-first order and pseudo-second order models; and diffusion-based external diffusion and Weber-Morris intraparticle models. Both SMP fractions were removed effectively, however, sorption of protein was significantly better than that of carbohydrate in all cases. The relatively significant effect of particle size on sorption of protein indicates that protein is most likely adsorbed as a single layer on the carbon surface. For the carbohydrate, the increase in particle size did not decrease the sorption significantly indicating that carbohydrate may be adsorbed in multiple layers or may diffuse into the porous matrix more effectively.

  16. Batch and column study: sorption of perfluorinated surfactants from water and cosolvent systems by Amberlite XAD resins.

    Science.gov (United States)

    Xiao, Feng; Davidsavor, Kerry Jade; Park, Sangyoo; Nakayama, Michio; Phillips, Brian Ray

    2012-02-15

    Amberlite XAD resins have been employed to a great extent as the sorbent for removing or concentrating organic compounds from different matrices. We present for the first time a systematic study on the sorption of perfluorochemical (PFC) surfactants, an emerging class of environmental contaminants, by XAD-7HP (moderately polar) and XAD-2 (nonpolar). The results show that XAD-7HP can strongly sorb PFCs at circumneutral pH; the isotherm-determined linear sorption coefficient can reach 10(6)L/kg. On the other hand, the sorption coefficient for XAD-2 was two orders of magnitude lower than that for XAD-7HP. PFC sorption on XAD-7HP increased with an increase of the perfluorocarbon chain length of PFC and a decrease of the solution pH, indicating the importance of hydrophobic and electrostatic effects. The sorption coefficient for XAD-7HP reduced markedly with increasing fraction of the organic cosolvent (methanol) in the water-cosolvent mixture; however, the trend could not be predicted by a log-linear cosolvency model. Furthermore, the statistical analysis of column test results showed that after regeneration XAD-7HP can be used at least eight times without significant loss of performance. Finally, the experimental results imply that XAD-7HP sorption of shorter-chained PFCs (≤5 perfluorinated carbons) from water can be thermodynamically favorable.

  17. Sorption and Dissipation of Tetracyclines in Soils and Compost

    Institute of Scientific and Technical Information of China (English)

    LI Ling-Ling; HUANG Li-Dong; CHUNG Ren-Shih; FOK Ka-Hang; ZHANG Yong-Song

    2010-01-01

    Two agricultural soils were collected from Dahu and Pinchen counties and swine manure compost(SMC)from Ping-tung County in Taiwan,China to investigate the sorption and dissipation of three tetracyclines(TCs),i.e.,oxytetracycline(OTC),tetracycline(TC)and chlortetracycline(CTC),in compost,soils and soil/compost mixtures with different organic carbon(OC)contents.There were seven treatments in total.TCs were most strongly adsorbed to SMC in all treatments due to the high OC content.When SMC was present in the soils,the sorption of TCs was significantly enhanced,which might be attributed to the increased OC content and CEC.The adsorption of TCs showed non-linear adsorption isotherms and fitted well to the Preundlich model.After 49 d of incubation at 25 ℃ in soils and soil/compost mixtures in the dark,TCs elapsed in all substrates,with the time required for 50% degradation(DT50)between 20 and 41 d,and the time for90% degradation(DT90)between 68 and 137 d.Soil amended with compost enhanced the stability of TCs and reduced their mobility.The dissipation of TCs in a soil environment was slow,indicating that these compounds might be persistent in soil.

  18. Selective polymer materials: absolute determination of their sorption properties

    Science.gov (United States)

    Jakusch, Michael; Mizaikoff, Boris

    2001-02-01

    Several types of selective materials are frequently used in chemical sensors such as natural antibodies, synthetic host substances (calixarenes, cyclodextrines, etc.) molecularly imprinted materials, or conventional polymers. For a systematic development of those materials, their sorption behavior for interesting analyte substances and potentially interfering compounds has to be thoroughly characterized, which can be a time-consuming and error-prone task. Moreover, using the respective sensor principle itself for this characterization an exact relation between the sensor signal and the underlying partition coefficient or sorption isotherm can often not be obtained. In this paper, we present an automated method for the direct determination of polymer/water partition coefficients of volatile organic compounds that consists of an automated fluid handling system, a dedicated partitioning cell and a purge-and-trap gas chromatography (PT-GC) unit. The main application of this novel system is the characterization of layer materials for infrared evanescent wave spectroscopic (IR-EWS) sensors, however an extension to other problems is conceivable. The whole experimental procedure comprising calibration of the GC system, preparation of test solutions, analyte partitioning, sample analysis, as well as the necessary cleaning steps is performed automatically under computer control. Hence, this system can be operated unattendedly, yielding a reasonable throughput with comparatively low expenditure of human labor.

  19. Sorption of cobalt in zeolites and natural clays of the clinoptilolite and kaolinite type; Sorcion de cobalto en zeolitas y arcillas naturales del tipo clinoptilolita y caolinita

    Energy Technology Data Exchange (ETDEWEB)

    Davila R, J.I.; Solache R, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2006-07-01

    In this work the sorption of cobalt of aqueous solutions in two natural zeolites (clinoptilolite) and a clay (kaolinite) of origin in the center-north region of Mexico is evaluated. The effect of the pH and the time of contact in the process of sorption were evaluated. The cobalt retained in the aluminosilicates was determined by neutron activation analysis. The cobalt sorption in the materials in a range of pH from 4 to 7 does not present significant variations. The studies of reaction kinetics show a very fast sorption in the first 5 hours of contact, reaching the equilibrium in approximately 24 hours. The kinetics of sorption of the cobalt ions was represented better by the Ritchie reaction model modified of second order. The experimental data for the zeolites obtained at ambient temperature and varying the concentration were adjusted to the models of Freundlich, Langmuir and Freundlich-Langmuir isotherms and it was observed that the cobalt sorption it behaves according to the Freundlich isotherm model. (Author)

  20. Sorption characteristics of polycyclic aromatic hydrocarbons in aluminum smelter residues.

    Science.gov (United States)

    Breedveld, Gijs D; Pelletier, Emilien; St Louis, Richard; Cornelissen, Gerard

    2007-04-01

    High temperature carbon oxidation in primary aluminum smelters results in the release of polycyclic aromatic hydrocarbons (PAH) into the environment. The main source of PAH are the anodes, which are composed of petroleum coke (black carbon, BC) and coal tar pitch. To elucidate the dominant carbonaceous phase controlling the environmental fate of PAH in aluminum smelter residues (coke BC and/or coal tar), the sorptive behavior of PAHs has been determined, using passive samplers and infinitesink desorption methods. Samples directly from the wet scrubber were studied as well as ones from an adjacent 20-year old storage lagoon and roof dust from the smelter. Carbon-normalized distribution coefficients of native PAHs were 2 orders of magnitude higher than expected based on amorphous organic carbon (AOC)/water partitioning, which is in the same order of magnitude as reported literature values for soots and charcoals. Sorption isotherms of laboratory-spiked deuterated phenanthrene showed strong (-100 times stronger than AOC) but nonetheless linear sorption in both fresh and aged aluminum smelter residues. The absence of nonlinear behavior typical for adsorption to BC indicates that PAH sorption in aluminum smelter residues is dominated by absorption into the semi-solid coal tar pitch matrix. Desorption experiments using Tenax showed that fresh smelter residues had a relatively large rapidly desorbing fraction of PAH (35-50%), whereas this fraction was strongly reduced (11-16%) in the lagoon and roof dust material. Weathering of the coal tar residue and/or redistribution of PAH between coal tar and BC phases could explain the reduced availability in aged samples.

  1. A Revised Multi-Fickian Moisture Transport Model To Describe Non-Fickian Effects In Wood

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Svensson, Staffan; Damkilde, Lars

    2007-01-01

    This paper presents a study and a refinement of the sorption rate model in a so-called multi-Fickian or multiphase model. This type of model describes the complex moisture transport system in wood, which consists of separate water vapor and bound-water diffusion interacting through sorption....... At high relative humidities, the effect of this complex moisture transport system becomes apparent, and since a single Fickian diffusion equation fails to model the behavior, it has been referred to as non-Fickian or anomalous behavior. At low relative humidities, slow bound-water transport and fast...... conditions for the model are discussed, since discrepancies from corresponding models of moisture transport in paper products have been found....

  2. A revised multi-Fickian moisture transport model to describe non-Fickian effects in wood

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Damkilde, Lars; Svensson, Staffan

    2007-01-01

    This paper presents a study and a refinement of the