Studies of the water adsorption on Lampung’s natural zeolite of Indonesia for cooling application

Science.gov (United States)

Wulandari, D. A.; Nasruddin; Lemington

2018-03-01

Part of minerals that originally formed from volcanic rock and ash layers reacting further with alkaline groundwater is called natural zeolite, where its sources are not always available in all countries. Indonesia is located in the ring of fire which have a huge sources of zeolite, one of the area is Lampung, South Sumatra. Natural zeolite has been considered as one of potential heat adsorbent medium which can contribute to the energy consumption and reduce air pollution in the using of cooling application. The characteristic of this Lampung natural zeolite such as adsorption kinetics, adsorption water uptake, and adsorption capacity were test with ASAP 2020 system. Sorption kinetics by this experiment of zeolite samples were carried out in a constant temperature and humidity chamber. The chamber can supply constant air condition with deviations of ±0.5 °C for temperature and ±3% for relative humidity. The data based on rate of adsorption and the defined working condition was set as 20°C and 70% RH. Pore volume is a significant parameter for determining the limitation of water uptake, which can describe the saturated condition of zeolite. Sorption isotherm models used to describe sorption phenomena are commonly deduced from the Polanyi potential theory were investigated. The water adsorption quantity increased with the increase of relative pressure. To sum up, this pure zeolite has a less heat and mass transfer performance so its need to be activated before using in cooling application to get their great potential and by being coated in a desiccant heat exchanger systems.

Modeling Ethanol Decomposition on Transition Metals: A Combined Application of Scaling and Bronsted-Evans-Polanyi Relations

DEFF Research Database (Denmark)

Ferrin, P.; Simonetti, D.; Kandoi, S.

2009-01-01

calculations necessary to describe trends in activity and selectivity across metal and alloy surfaces, thus extending the reach of DFT to more complex systems. In-this work, the well-known family of Bronsted-Evans-Polanyi (BEP) correlations, connecting minima with maxima in the potential energy surface...... on a subset of these surfaces are calculated. Experiments on supported catalysts verify that this simple model is reasonably accurate in describing reactivity trends across metals, suggesting that the combination of BEP and scaling relations may substantially reduce the cost of DFT calculations required...

Karl Polanyi e o "Grande Debate" entre substantivistas e formalistas na antropologia econômica Karl Polanyi and the "Great Debate" between the substantivists and formalists in economic anthropology

Directory of Open Access Journals (Sweden)

Nuno Miguel Cardoso Machado

2012-04-01

Full Text Available Na raiz do pensamento Polanyiano, encontra-se a distinção entre economia no sentido substantivo e economia no sentido formal. Com efeito, a concepção substantivista - que define a economia como um processo instituído de interação entre o homem e o ambiente natural e social que o rodeia e resulta em contínua oferta de meios para satisfazer as necessidades humanas - constitui a base do método preconizado pelo autor: a análise institucional. Com tal distinção, Polanyi (1977a pretende evitar a "falácia economicista" que consiste na identificação automática da economia com sua forma de mercado. Ao contrário, só na moderna economia capitalista é que um "sistema de mercados formadores de preços" desempenha papel fundamental. Essas questões foram alvo de um "Grande Debate" entre as correntes substantivista - encabeçada por Polanyi - e formalista no contexto da disciplina da Antropologia Econômica.At the root of Polanyian thought, a distinction can be found between the substantive and formal concepts of the economy. In fact, the substantivist conception, that defines the economy as an instituted process of interaction between man and its natural and social environment, which results in a continuous supply of material means to meet human needs, constitutes the basis of the method recommended by the author: institutional analysis. With this distinction, Polanyi intends to avoid the "economistic fallacy", which consists of the automatic identification of the economy in its market form. Only in the modern capitalist economy does a system of "price-making markets" play a fundamental role. These questions were amply discussed in the so-called "Great Debate" between the substantivist and formalist schools of thought in the discipline of Economic Anthropology.

Adsorption of tetracycline on soil and sediment: Effects of pH and the presence of Cu(II)

International Nuclear Information System (INIS)

Zhang Zheyun; Sun Ke; Gao Bo; Zhang Guixiang; Liu Xitao; Zhao Ye

2011-01-01

Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K OC ) and PMM saturated adsorption capacity (Q OC 0 ) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH < 5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH.

Unintended Learning in Primary School Practical Science Lessons from Polanyi's Perspective of Intellectual Passion

Science.gov (United States)

Park, Jisun; Song, Jinwoong; Abrahams, Ian

2016-01-01

This study explored, from the perspective of intellectual passion developed by Michael Polanyi, the unintended learning that occurred in primary practical science lessons. We use the term "unintended" learning to distinguish it from "intended" learning that appears in teachers' learning objectives. Data were collected using…

On the behavior of Brønsted-Evans-Polanyi relations for transition metal oxides

DEFF Research Database (Denmark)

Vojvodic, Aleksandra; Vallejo, Federico Calle; Guo, Wei

2011-01-01

Versatile Brønsted-Evans-Polanyi (BEP) relations are found from density functional theory for a wide range of transition metal oxides including rutiles and perovskites. For oxides, the relation depends on the type of oxide, the active site, and the dissociating molecule. The slope of the BEP...

Effect of temperature on microbial growth rate - thermodynamic analysis, the arrhenius and eyring-polanyi connection

Science.gov (United States)

The objective of this work is to develop a new thermodynamic mathematical model for evaluating the effect of temperature on the rate of microbial growth. The new mathematical model is derived by combining the Arrhenius equation and the Eyring-Polanyi transition theory. The new model, suitable for ...

Correlations and adsorption mechanisms of aromatic compounds on biochars produced from various biomass at 700 °C.

Science.gov (United States)

Yang, Kun; Jiang, Yuan; Yang, Jingjing; Lin, Daohui

2018-02-01

Knowledge of adsorption behavior of organic contaminants on high heat temperature treated biochars is essential for application of biochars as adsorbents in wastewater treatment and soil remediation. In this study, isotherms of 25 aromatic compounds adsorption on biochars pyrolyzed at 700 °C from biomass including wood chips, rice straw, bamboo chips, cellulose, lignin and chitin were investigated to establish correlations between adsorption behavior and physicochemical properties of biochars. Isotherms were well fitted by Polanyi theory-based Dubinin-Ashtakhov (DA) model with three parameters, i.e., adsorption capacity (Q 0 ) and adsorption affinity (E and b). Besides the negative correlation of Q 0 with molecular maximum cross-sectional areas (σ) of organic compounds, positive correlations of Q 0 with total pore volume (V total ) and average diameter of micropore (D) of biochars were observed, indicating that adsorption by biochars is captured by the pore-filling mechanism with molecular sieving effect in biochar pores. Linear solvation energy relationships (LSERs) of adsorption affinity (E) with solvatochromic parameters of organic compounds (i. e., α m and π ∗ ) were established, suggesting that hydrophobic effect, π-π interaction and hydrogen-bonding interaction are the main forces responsible for adsorption. The regression coefficient (π 1 ) and intercept (C) of obtained LSERs are correlated with biochar H/C and R micro , respectively, implying that biochars with higher aromaticity and more micropores have stronger π-π bonding potential and hydrophobic effect potential with aromatic molecule, respectively. However, hydrogen-bonding potential of biochars for organic molecules is not changed significantly with properties of biochars. A negative correlation of b with biochar H/C is also obtained. These correlations could be used to predict the adsorption behavior of organic compounds on high heat temperature treated biochars from various biomass for

Modeling of boldine alkaloid adsorption onto pure and propyl-sulfonic acid-modified mesoporous silicas. A comparative study

Energy Technology Data Exchange (ETDEWEB)

Geszke-Moritz, Małgorzata, E-mail: Malgorzata.Geszke-Moritz@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Moritz, Michał, E-mail: michal.moritz@put.poznan.pl [Poznan University of Technology, Faculty of Chemical Technology, Institute of Chemistry and Technical Electrochemistry, Berdychowo 4, 60-965 Poznań (Poland)

2016-12-01

The present study deals with the adsorption of boldine onto pure and propyl-sulfonic acid-functionalized SBA-15, SBA-16 and mesocellular foam (MCF) materials. Siliceous adsorbents were characterized by nitrogen sorption analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric analysis. The equilibrium adsorption data were analyzed using the Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherms. Moreover, the Dubinin-Radushkevich and Dubinin-Astakhov isotherm models based on the Polanyi adsorption potential were employed. The latter was calculated using two alternative formulas including solubility-normalized (S-model) and empirical C-model. In order to find the best-fit isotherm, both linear regression and nonlinear fitting analysis were carried out. The Dubinin-Astakhov (S-model) isotherm revealed the best fit to the experimental points for adsorption of boldine onto pure mesoporous materials using both linear and nonlinear fitting analysis. Meanwhile, the process of boldine sorption onto modified silicas was described the best by the Langmuir and Temkin isotherms using linear regression and nonlinear fitting analysis, respectively. The values of adsorption energy (below 8 kJ/mol) indicate the physical nature of boldine adsorption onto unmodified silicas whereas the ionic interactions seem to be the main force of alkaloid adsorption onto functionalized sorbents (energy of adsorption above 8 kJ/mol). - Graphical abstract: Modeling of boldine adsorption onto unmodified and propyl-sulfonic acid-modified mesoporous adsorbents. - Highlights: • The process of boldine adsorption onto SBA-15, SBA-16 and MCF silicas was examined. • Siliceous adsorbents were functionalized with propyl-sulfonic acid groups. • The equilibrium adsorption data were analyzed using several isotherm models. • Both linear regression and nonlinear fitting analysis were carried out. �

Adsorption of polycyclic aromatic hydrocarbons on graphene oxides and reduced graphene oxides.

Science.gov (United States)

Sun, Yubing; Yang, Shubin; Zhao, Guixia; Wang, Qi; Wang, Xiangke

2013-11-01

Graphene has attracted increasing attention in multidisciplinary studies because of its unique physical and chemical properties. Herein, the adsorption of polycyclic aromatic hydrocarbons (PAHs), such as naphthalene (NAP), anthracene (ANT), and pyrene (PYR), on reduced graphene oxides (rGOs) and graphene oxides (GOs) as a function of pH, humic acid (HA), and temperature were elucidated by means of a batch technique. For comparison, nonpolar and nonporous graphite were also employed in this study. The increasing of pH from 2 to 11 did not influence the adsorption of PAHs on rGOs, whereas the suppressed adsorption of NAP on rGOs was observed both in the presence of HA and under high-temperature conditions. Adsorption isotherms of PAHs on rGOs were in accordance with the Polanyi-Dubinin-Ashtahhov (PDA) model, providing evidence that pore filling and flat surface adsorption were involved. The saturated adsorbed capacities (in mmol g(-1)) of rGOs for PAHs calculated from the PDA model significantly decreased in the order of NAP>PYR>ANT, which was comparable to the results of theoretical calculations. The pore-filling mechanism dominates the adsorption of NAP on rGOs, but the adsorption mechanisms of ANT and PYR on rGOs are flat surface adsorption. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water Adsorption and Dissociation on Ceria-Supported Single-Atom Catalysts: A First-Principles DFT+U Investigation.

Science.gov (United States)

Han, Zhong-Kang; Gao, Yi

2016-02-01

Single-atom catalysts have attracted wide attention owing to their extremely high atom efficiency and activities. In this paper, we applied density functional theory with the inclusion of the on-site Coulomb interaction (DFT+U) to investigate water adsorption and dissociation on clean CeO 2 (111) surfaces and single transition metal atoms (STMAs) adsorbed on the CeO 2 (111) surface. It is found that the most stable water configuration is molecular adsorption on the clean CeO 2 (111) surface and dissociative adsorption on STMA/CeO 2 (111) surfaces, respectively. In addition, our results indicate that the more the electrons that transfer from STMA to the ceria substrate, the stronger the binding energies between the STMA and ceria surfaces. A linear relationship is identified between the water dissociation barriers and the d band centers of STMA, known as the generalized Brønsted-Evans-Polanyi principle. By combining the oxygen spillovers, single-atom dispersion stabilities, and water dissociation barriers, Zn, Cr, and V are identified as potential candidates for the future design of ceria-supported single-atom catalysts for reactions in which the dissociation of water plays an important role, such as the water-gas shift reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Karl Polanyi et les monnaies modernes : un réexamen

OpenAIRE

Blanc , Jérôme

2006-01-01

Karl Polanyi a établi une célèbre distinction entre "all purpose money", caractéristiques des sociétés modernes, et "special purpose money", caractéristiques des sociétés anciennes. C'est la conception polanyienne des monnaies modernes qui est critiquée dans ce texte : non seulement elle conduit à considérer que les sociétés modernes ne connaissent pas de "special purpose money", mais en plus elle ne permet pas de renouveler la conception courante de la monnaie (sous-entendu moderne) qui en f...

Direct NO decomposition over stepped transition-metal surfaces

DEFF Research Database (Denmark)

Falsig, Hanne; Bligaard, Thomas; Christensen, Claus H.

2007-01-01

We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition-metal surfaces by combining a database of adsorption energies on stepped metal surfaces with known Bronsted-Evans-Polanyi (BEP) relations for the activation barriers of dissociation...

Adsorption of diuron and dichlobenil on multiwalled carbon nanotubes as affected by lead.

Science.gov (United States)

Chen, Guang-Cai; Shan, Xiao-Quan; Pei, Zhi-Guo; Wang, Huanhua; Zheng, Li-Rong; Zhang, Jing; Xie, Ya-Ning

2011-04-15

The effect of lead on the adsorption of diuron and dichlobenil on multiwalled carbon nanotubes (MWCNTs) was investigated to explore the possible application of MWCNTs for removal of both herbicides from contaminated water. The adsorption of diuron and dichlobenil on MWCNTs at pH 6 was nonlinear and fit the Polanyi-Manes model well. The adsorption of diuron and dichlobenil was closely correlated with specific surface areas and micropore volumes of MWCNTs. An increase in oxygen content of MWCNTs with same diameters and similar surface areas decreased the adsorption of diuron and dichlobenil, while increased the adsorption of lead. Micro-Fourier transform infrared spectroscopic study indicated that hydrogen bonding is a main mechanism responsible for the adsorption of diuron or dichlobenil onto MWCNTs-O. Oxygen containing groups, mainly carboxylic groups, significantly increased the adsorption of lead through the formations of outer-sphere and inner-sphere complexes, which are verified by X-ray absorption spectroscopic measurements. Oxygen containing groups and the presence of lead diminished the adsorption of diuron and dichlobenil. The suppression mechanisms of lead were ascribed to hydration and complexation of lead with carboxylic groups, which may occupy part of surface of MWCNTs-O. The large hydration shell of lead cations may intrude or shield hydrophobic and hydrophilic sites, resulting in a decreased adsorption of diuron and dichlobenil at the lead-complexed moieties. Copyright © 2011 Elsevier B.V. All rights reserved.

Potential theory of adsorption for associating mixtures: possibilities and limitations

DEFF Research Database (Denmark)

Bjørner, Martin Gamel; Shapiro, Alexander; Kontogeorgis, Georgios

2013-01-01

The applicability of the Multicomponent Potential Theory of Adsorption (MPTA) for prediction of the adsorption equilibrium of several associating binary mixtures on different industrial adsorbents is investigated. In the MPTA the adsorbates are considered to be distributed fluids subject...... to describe the solid-fluid interactions. The potential is extended to include adsorbate-absorbent specific capacities rather than an adsorbent specific capacity. Correlations of pure component isotherms are generally excellent with individual capacities, although adsorption on silicas at different...... temperatures still poses a challenge. The quality of the correlations is usually independent on the applied EoS. Predictions for binary mixtures indicate that the MPTA+SRK is superior when adsorption occurs on non-polar or slightly polar adsorbents, while MPTA+CPA performs better for polar adsorbents, or when...

Elementary Steps of Syngas Reactions on Mo2C(001): Adsorption Thermochemistry and Bond Dissociation

Energy Technology Data Exchange (ETDEWEB)

Medford, Andrew

2012-02-16

Density functional theory (DFT) and ab initio thermodynamics are applied in order to investigate the most stable surface and subsurface terminations of Mo{sub 2}C(001) as a function of chemical potential and in the presence of syngas. The Mo-terminated (001) surface is then used as a model surface to evaluate the thermochemistry and energetic barriers for key elementary steps in syngas reactions. Adsorption energy scaling relations and Broensted-Evans-Polanyi relationships are established and used to place Mo{sub 2}C into the context of transition metal surfaces. The results indicate that the surface termination is a complex function of reaction conditions and kinetics. It is predicted that the surface will be covered by either C{sub 2}H{sub 2} or O depending on conditions. Comparisons to transition metals indicate that the Mo-terminated Mo{sub 2}C(001) surface exhibits carbon reactivity similar to transition metals such as Ru and Ir, but is significantly more reactive towards oxygen.

The Consequences of the Progress and Market Economy: Karl Polanyi's Reflections Applicable to Neoliberalism

Directory of Open Access Journals (Sweden)

Juliana Mongon Petroni

2015-12-01

Full Text Available As a consequence of the progress after the Industrial Revolution, the values of society, economy  and  politics  have  changed.  The  market economy  was  allowed,  generating  a catastrophic dislocation in people's lives. Polanyis "Satanic Mill" is the process that crunched men and turned then into mass. Social relations were inserted into the economic system and human society became an accessory of it. With the expansion and organization of global markets, the society had to protected itself against the risks of self-regulated market system. Although there are economic advantages in a free labor market, these do not justify the potential social destruction.  However, nowadays  the  idea  of  deregulation  to  allow competition and international competitiveness of goods. Our contemporary society has changed its values and the money was prioritized instead of human life. Today, men have become just a commodity. In fact, a fictitious commodity.

Study of high-pressure adsorption from supercritical fluids by the potential theory

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2009-01-01

The multicomponent potential theory of adsorption (MPTA), which has been previously used to study low-pressure adsorption of subcritical fluids, is extended to adsorption equilibria from supercritical fluids up to high pressures. The MPTA describes an adsorbed phase as an inhomogeneous fluid...... the adsorbed and the gas phases. We have also evaluated the performance of the classical Soave-Redlich-Kwong (SRK) EoS. The fluid-solid interactions are described by simple Dubinin-Radushkevich-Astakhov (DRA) potentials. In addition, we test the performance of the 10-4-3 Steele potential. It is shown...... that application of sPC-SAFT slightly improves the performance of the MPTA and that in spite of its simplicity, the DRA model can be considered as an accurate potential, especially, for mixture adsorption. We show that, for the sets of experimental data considered in this work, the MPTA is capable of predicting...

A Symposium on the Relevance of Michael Polanyi's Insights to a Reformulated Understanding of Science, Technology, and Society

Science.gov (United States)

Mead, Walter B.

2011-01-01

This is intended as an introductory statement to the explorations undertaken in the essays that follow. The authors of these essays attempt to introduce the reader to some of the insights of Michael Polanyi and their implications for the reader who wishes to come to a greater understanding of modern technological society, which--for better or…

Prediction of adsorption from liquid mixtures in microporous media by the potential theory

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2007-01-01

Despite its industrial importance, adsorption from the liquid phase has been studied much less extensively than adsorption from the gas phase. In this paper, we study the adsorption of liquid mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). The MPTA is based on t...

Os principios de economia substantiva de Karl Polanyi em relações de economia solidária: o caso do povoado Cruz (Currais Novos/RN [doi: 10.5329/RECADM.20111002007

Directory of Open Access Journals (Sweden)

Fabiano André Gonçalves Silva

2011-12-01

Full Text Available OS PRINCIPIOS DE ECONOMIA SUBSTANTIVA DE KARL POLANYI EM RELAÇÕES DE ECONOMIA SOLIDÁRIA: O CASO DO POVOADO CRUZ (CURRAIS NOVOS/RN RESUMO Este estudo aborda relações econômicas e sociais em uma comunidade de fruticultores à luz dos princípios expostos por Polanyi (2000 na obra “A Grande Transformação” e dos pressupostos básicos da Nova Sociologia Econômica (NSE e da Economia Solidária. A unidade de observação foi o Povoado Cruz, no município de Currais Novos (RN. A técnica utilizada foi a observação não participante, com abordagem qualitativa na análise de dados. Em uma aproximação com a realidade buscou-se identificar como, e se, relações sociais não capitalistas, balizadas nos princípios de reciprocidade, domesticidade e redistribuição, sobrevivem em meio a relação capitalista. Percebeu-se que, mesmo dentro da realidade de mercado, predominam princípios elencados por Polanyi e pela Economia Solidária. Tais princípios têm base em valores como solidariedade, integração, respeito, ajuda mútua, cooperação e autonomia.   Palavras-Chave Reciprocidade; Redistribuição; Domesticidade; Economia Solidária; Agroindústria Familiar.     PRINCIPLES OF ECONOMICS SUBSTANTIVE OF KARL POLANYI RELATIONS IN SOLIDARITY ECONOMY: THE CASE OF CRUZ VILLAGE (CURRAIS NOVOS/RN   ABSTRACT This study focuses economic and social relationships in a fruit culture community under the prism of both principles established by Polanyi (2000 in his work “The Great Transformation” and central assumptions of New Economic Sociology (NES and Solidarity Economy. The community of Povoado cruz, in the municipality of Currais Novos (Rio Grande do Norte - Brazil, was studied through non-participant observation, and data gathered was analyzed with a qualitative approach. The paper aims at identifying how, and if, social not capitalist relationships, guided by reciprocity, domesticity and redistribution principles, survive within the

Adsorption of metal atoms at a buckled graphene grain boundary using model potentials

International Nuclear Information System (INIS)

Helgee, Edit E.; Isacsson, Andreas

2016-01-01

Two model potentials have been evaluated with regard to their ability to model adsorption of single metal atoms on a buckled graphene grain boundary. One of the potentials is a Lennard-Jones potential parametrized for gold and carbon, while the other is a bond-order potential parametrized for the interaction between carbon and platinum. Metals are expected to adsorb more strongly to grain boundaries than to pristine graphene due to their enhanced adsorption at point defects resembling those that constitute the grain boundary. Of the two potentials considered here, only the bond-order potential reproduces this behavior and predicts the energy of the adsorbate to be about 0.8 eV lower at the grain boundary than on pristine graphene. The Lennard-Jones potential predicts no significant difference in energy between adsorbates at the boundary and on pristine graphene. These results indicate that the Lennard-Jones potential is not suitable for studies of metal adsorption on defects in graphene, and that bond-order potentials are preferable

Karl Polanyi, la Nouvelle sociologie économique et les forces du marché

Directory of Open Access Journals (Sweden)

Ronan Le Velly

2008-12-01

Full Text Available Cet article montre en quoi plusieurs auteurs de la Nouvelle sociologie économique tendent à adopter un regard incomplet sur les forces du marché. Pour cela, l’auteur distingue deux notions d’encastrement renvoyant pour la première à un cadre méthodologique institutionnaliste et pour la seconde à l’observation du poids variable des forces du marché. Il établit qu’autant des sociologues classiques comme Weber ou Polanyi ont su coupler ces deux approches, autant plusieurs travaux majeurs de la Nouvelle sociologie économique, notamment ceux de Zelizer, de Fligstein et de Biggart, adoptent la première perspective mais ne traitent que de façon partielle de la seconde. L’auteur met particulièrement en cause les objets de recherche retenus par ces derniers auteurs, dès lors que sont systématiquement privilégiées des situations où les forces du marché sont tenues à l’écart.This article shows how many authors of the New Economic Sociology tend to adopt an incomplete view of market forces. The author distinguishes two notions of embeddedness, one related to the institutionalist theories and the second to the observation of the variable weight of market forces. It is established that classical sociologists such as Weber or Polanyi have joined these two approaches, while manyu works of the New sociological economy, for examle those of Zelizer, Fligstein or Biggart adopt the first perspective, but only treat the second partially. The author particularly questions the research objects chosen by these authors, since he considers that they generally refer to situations where market forces are held at bay.

Correlations and adsorption mechanisms of aromatic compounds on a high heat temperature treated bamboo biochar

International Nuclear Information System (INIS)

Yang, Kun; Yang, Jingjing; Jiang, Yuan; Wu, Wenhao; Lin, Daohui

2016-01-01

Adsorption of aromatic compounds, including polycyclic aromatic hydrocarbons, nitrobenzenes, phenols, and anilines, on a bamboo biochar produced at 700 °C (Ba700) was investigated with the mechanism discussion by isotherm fitting using the Polanyi-theory based Dubinin–Ashtakhov (DA) model. Correlations of adsorption capacity (Q 0 ) of organic compounds with their molecular sizes and melting points, as well as correlations of adsorption affinity (E) with their solvatochromic parameters (i.e., π* and α m ), on the biochar, were developed and indicating that adsorption is captured by the pore filling mechanism and derived from the hydrophobic effects of organic compounds and the forming of π-π electron donor-acceptor (EDA) interactions and hydrogen bonding interactions of organic molecules with surface sites of the biochar. The effects of organic molecular sizes and melting points on adsorption capacity are ascribed to the molecular sieving effect and the packing efficiency of the organic molecules in the biochar pores, respectively. These correlations can be used to quantitatively estimate the adsorption of organic compounds on biochars from their commonly physicochemical properties including solvatochromic parameters, melting points and molecular cross-sectional area. The prediction using these correlations is important for assessing the unknown adsorption behaviors of new organic compounds and also helpful to guide the surface modification of biochars and make targeted selection in the environmental applications of biochars as adsorbents. - Highlights: • Adsorption of organic chemicals on biochars are captured by pore filling mechanism. • Adsorption is derived from Van der Waals force, π-π EDA and H-bonding interactions. • Adsorption capacity is negatively correlated with organic molecular sizes/melting points. • Adsorption capacity is restricted by molecular sieving effect and packing efficiency. • Adsorption affinity has a LSER with chemical

Una lectura de Polanyi desde la economía social y solidaria en América Latina

OpenAIRE

Coraggio, José Luis

2014-01-01

Se presentan elementos del pensamiento social y de conceptos desarrollados por Karl Polanyi, en confrontación con el liberalismo económico, haciendo un paralelo con la lucha actual contra el neoliberalismo. Se plantean diferencias que surgen al hacer una lectura desde América Latina: un sesgo que podría calificarse como eurocéntrico, que excluye consideraciones sobre la co-constitución de AMérica y Europa, la heterogeneidad estructural que nos hace economías de mercado incompleta. A la vez se...

The effects of ion adsorption on the potential of zero charge and the differential capacitance of charged aqueous interfaces

Science.gov (United States)

Uematsu, Yuki; Netz, Roland R.; Bonthuis, Douwe Jan

2018-02-01

Using a box profile approximation for the non-electrostatic surface adsorption potentials of anions and cations, we calculate the differential capacitance of aqueous electrolyte interfaces from a numerical solution of the Poisson-Boltzmann equation, including steric interactions between the ions and an inhomogeneous dielectric profile. Preferential adsorption of the positive (negative) ion shifts the minimum of the differential capacitance to positive (negative) surface potential values. The trends are similar for the potential of zero charge; however, the potential of zero charge does not correspond to the minimum of the differential capacitance in the case of asymmetric ion adsorption, contrary to the assumption commonly used to determine the potential of zero charge. Our model can be used to obtain more accurate estimates of ion adsorption properties from differential capacitance or electrocapillary measurements. Asymmetric ion adsorption also affects the relative heights of the characteristic maxima in the differential capacitance curves as a function of the surface potential, but even for strong adsorption potentials the effect is small, making it difficult to reliably determine the adsorption properties from the peak heights.

On the behavior of Bronsted-Evans-Polanyi Relations for Transition Metal Oxides

Energy Technology Data Exchange (ETDEWEB)

Vojvodic, Aleksandra

2011-08-22

Versatile Broensted-Evans-Polanyi (BEP) relations are found from density functional theory for a wide range of transition metal oxides including rutiles and perovskites. For oxides, the relation depends on the type of oxide, the active site and the dissociating molecule. The slope of the BEP relation is strongly coupled to the adsorbate geometry in the transition state. If it is final state-like the dissociative chemisorption energy can be considered as a descriptor for the dissociation. If it is initial state-like, on the other hand, the dissociative chemisorption energy is not suitable as descriptor for the dissociation. Dissociation of molecules with strong intramolecular bonds belong to the former and molecules with weak intramolecular bonds to the latter group. We show, for the prototype system La-perovskites, that there is a 'cyclic' behavior in the transition state characteristics upon change of the active transition metal of the oxide.

A review on the removal of antibiotics by carbon nanotubes.

Science.gov (United States)

Cong, Qiao; Yuan, Xing; Qu, Jiao

2013-01-01

Increasing concerns have been raised regarding the potential risks of antibiotics to human and ecological health due to their extensive use. Carbon nanotubes (CNTs) have drawn special research attention because of their unique properties and potential applications as a kind of adsorbents. This review summarizes the currently available research on the adsorption of antibiotics on CNTs, and will provide useful information for CNT application and risk assessment. Four different models, the Freundlich model (FM), Langmuir model (LM), Polanyi-Mane model (PMM), and Dubinin-Ashtakhov model (DAM), are often used to fit the adsorption isotherms. Because different mechanisms may act simultaneously, including electrostatic interactions, hydrophobic interactions, π-π bonds, and hydrogen bonds, the prediction of organic chemical adsorption on CNTs is not straightforward. Properties of CNTs, such as specific surface area, adsorption sites, and oxygen content, may influence the adsorption of antibiotics on CNTs. Adsorption heterogeneity and hysteresis are two features of antibiotic-CNT interactions. In addition, CNTs with adsorbed antibiotics may have potential risks for human health. So, further research examining how to reduce such risks is needed.

Unintended Learning in Primary School Practical Science Lessons from Polanyi's Perspective of Intellectual Passion

Science.gov (United States)

Park, Jisun; Song, Jinwoong; Abrahams, Ian

2016-03-01

This study explored, from the perspective of intellectual passion developed by Michael Polanyi, the unintended learning that occurred in primary practical science lessons. We use the term `unintended' learning to distinguish it from `intended' learning that appears in teachers' learning objectives. Data were collected using video and audio recordings of a sample of twenty-four whole class practical science lessons, taught by five teachers, in Korean primary schools with 10- to 12-year-old students. In addition, video and audio recordings were made for each small group of students working together in order to capture their activities and intra-group discourse. Pre-lesson interviews with the teachers were undertaken and audio-recorded to ascertain their intended learning objectives. Selected key vignettes, including unintended learning, were analysed from the perspective of intellectual passion developed by Polanyi. What we found in this study is that unintended learning could occur when students got interested in something in the first place and could maintain their interest. In addition, students could get conceptual knowledge when they tried to connect their experience to their related prior knowledge. It was also found that the processes of intended learning and of unintended learning were different. Intended learning was characterized by having been planned by the teacher who then sought to generate students' interest in it. In contrast, unintended learning originated from students' spontaneous interest and curiosity as a result of unplanned opportunities. Whilst teachers' persuasive passion comes first in the process of intended learning, students' heuristic passion comes first in the process of unintended learning. Based on these findings, we argue that teachers need to be more aware that unintended learning, on the part of individual students, can occur during their lesson and to be able to better use this opportunity so that this unintended learning can be

Influence of Surface Charge/Potential of a Gold Electrode on the Adsorptive/Desorptive Behaviour of Fibrinogen

International Nuclear Information System (INIS)

Dargahi, Mahdi; Konkov, Evgeny; Omanovic, Sasha

2015-01-01

Highlights: • Adsorptive/desorptive behavior of fibrinogen (FG) on an electrochemically-polarized gold substrate is reported. • The adsorption affinity of FG (afFG) is constant on a negatively-charged substrate surface. • The afFG increases linearly with an increase in positive substrate surface charge. • The FG adsorption kinetics is strongly dependant on substrate surface charge. • The adsorbed FG layer can be desorbed by electrochemical evolution of hydrogen and oxygen. - Abstract: The effect of gold substrate surface charge (potential) on adsorptive/desorptive behaviour of fibrinogen (FG) was studied by employing differential capacitance (DC) and polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), in terms of FG adsorption thermodynamics, kinetics, and desorption kinetics. The gold substrate surface charge was modulated in-situ within the electrochemical double-layer region by means of electrochemical potentiostatic polarization in a FG-containing electrolyte, thus avoiding the interference of other physico-chemical properties of the gold surface on FG’s interfacial behaviour. The FG adsorption equilibrium was modeled using the Langmuir isotherm. Highly negative values of apparent Gibbs free energy of adsorption (ranging from from −52.1 ± 0.4 to −55.8 ± 0.8 kJ mol −1 , depending on the FG adsorption potential) indicated a highly spontaneous and strong adsorption of FG onto the gold surface. The apparent Gibbs free energy of adsorption was found to be independent of surface charge when the surface was negatively charged. However, when the gold surface was positively charged, the apparent Gibbs free energy of adsorption exhibited a pronounced linear relationship with the surface charge, shifting to more negative values with an increase in positive electrode potential. The adsorption kinetics of FG was also found to be dependent on gold surface charge in a similar manner to the apparent Gibbs free energy of adsorption

Recombinant albumin adsorption on mica studied by AFM and streaming potential measurements.

Science.gov (United States)

Kujda, Marta; Adamczyk, Zbigniew; Morga, Maria; Sofińska, Kamila

2015-03-01

Recombinant human serum albumin (rHSA) in monomeric state is widely used in pharmaceutical industry as a drug excipient and for preparing coatings for medical devices. In this work the adsorption process of rHSA on model mica surface at pH 3.5 was studied using the atomic force microscopy (AFM) and in situ streaming potential measurements. The kinetics of albumin adsorption was determined by a direct enumeration of single molecules over various substrate areas. These results were consistent with streaming potential measurements carried out for the parallel-plate channel flow and with theoretical predictions derived from the random sequential adsorption (RSA) model. Desorption kinetics of albumin under flow conditions was also evaluated via the streaming potential measurements. In this way, the amount of irreversibly bound albumin was quantitatively evaluated to be 0.64 and 1.2 mg m(-2) for ionic strength of 0.01 and 0.15 M, respectively. This agrees with previous results obtained for HSA and theoretical calculations derived from the RSA model. Additionally, it was demonstrated that there existed a fraction of reversibly bound albumin that can be fully eluted within a few hours. The binding energy of these fraction of molecules was -18 kT that is consistent with the electrostatic controlled adsorption mechanism of albumin at this pH. It was concluded that the rHSA monolayers of well-defined coverage can find applications for quantitatively analyzing ligand binding and for performing efficient biomaterials and immunological tests. Copyright © 2015 Elsevier B.V. All rights reserved.

Metal-Organic Frameworks in Adsorption-Driven Heat Pumps: The Potential of Alcohols as Working Fluids.

Science.gov (United States)

de Lange, Martijn F; van Velzen, Benjamin L; Ottevanger, Coen P; Verouden, Karlijn J F M; Lin, Li-Chiang; Vlugt, Thijs J H; Gascon, Jorge; Kapteijn, Freek

2015-11-24

A large fraction of global energy is consumed for heating and cooling. Adsorption-driven heat pumps and chillers could be employed to reduce this consumption. MOFs are often considered to be ideal adsorbents for heat pumps and chillers. While most published works to date on this topic have focused on the use of water as a working fluid, the instability of many MOFs to water and the fact that water cannot be used at subzero temperatures pose certain drawbacks. The potential of using alcohol-MOF pairs in adsorption-driven heat pumps and chillers is investigated. To this end, 18 different selected MOF structures in combination with either methanol or ethanol as a working fluid are considered, and their potential is assessed on the basis of adsorption measurements and thermodynamic efficiencies. If alcohols are used instead of water, then (1) adsorption occurs at lower relative pressures for methanol and even lower pressure for ethanol, (2) larger pores can be utilized efficiently, as hysteresis is absent for pores smaller than 3.4 nm (2 nm for water), (3) larger pore sizes need to be employed to ensure the desired stepwise adsorption, (4) the effect of (polar/apolar) functional groups in the MOF is far less pronounced, (5) the energy released or taken up per cycle is lower, but heat and mass transfer may be enhanced, (6) stability of MOFs seems to be less of an issue, and (7) cryogenic applications (e.g., ice making) become feasible. From a thermodynamic perspective, UiO-67, CAU-3, and ZIF-8 seem to be the most promising MOFs for both methanol and ethanol as working fluids. Although UiO-67 might not be completely stable, both CAU-3 and ZIF-8 have the potential to be applied, especially in subzero-temperature adsorption chillers (AC).

Surface potential of methyl isobutyl carbinol adsorption layer at the air/water interface.

Science.gov (United States)

Phan, Chi M; Nakahara, Hiromichi; Shibata, Osamu; Moroi, Yoshikiyo; Le, Thu N; Ang, Ha M

2012-01-26

The surface potential (ΔV) and surface tension (γ) of MIBC (methyl isobutyl carbinol) were measured on the subphase of pure water and electrolyte solutions (NaCl at 0.02 and 2 M). In contrast to ionic surfactants, it was found that surface potential gradually increased with MIBC concentration. The ΔV curves were strongly influenced by the presence of NaCl. The available model in literature, in which surface potential is linearly proportional to surface excess, failed to describe the experimental data. Consequently, a new model, employing a partial charge of alcohol adsorption layer, was proposed. The new model predicted the experimental data consistently for MIBC in different NaCl solutions. However, the model required additional information for ionic impurity to predict adsorption in the absence of electrolyte. Such inclusion of impurities is, however, unnecessary for industrial applications. The modeling results successfully quantify the influence of electrolytes on surface potential of MIBC, which is critical for froth stability.

Austeridad, democracia y financiarización: Relevancia de K. Polanyi en una economía monetaria de producción en la post-crisis

Directory of Open Access Journals (Sweden)

Alicia Girón

2015-05-01

Full Text Available La importancia de la moneda y el dinero crédito en Polanyi, base de la estabilidad de las relaciones de intercambio en una sociedad, establece una relación de causalidad entre democracia y libertad del ser humano en una economía monetaria de producción. En la coyuntura actual, La Gran transformación otorga elementos para debatir las políticas de austeridad a partir del prevaleciente deterioro de la democracia y la libertad en el actual periodo post-crisis. La austeridad ha obstaculizado las relaciones de intercambio al disminuir la creación de riqueza y las oportunidades de empleo. No sólo ha subsumido al ser humano al capital rentista, sino que además ha trastocado al propio mercado. Uno de los pilares de una sociedad democrática es la existencia de un sistema monetario que garantice las relaciones sociales del intercambio y el dinero crédito bajo los principios de la ética, la justicia social y la libertad. La democracia y la libertad desde la visión de Polanyi coexisten a través del buen desempeño de las relaciones monetarias de intercambio y de crédito definitorias para el acceso al empleo a través de un Estado regulador que garantice el bienestar económico.

A Classical Potential to Model the Adsorption of Biological Molecules on Oxidized Titanium Surfaces.

Science.gov (United States)

Schneider, Julian; Ciacchi, Lucio Colombi

2011-02-08

The behavior of titanium implants in physiological environments is governed by the thin oxide layer that forms spontaneously on the metal surface and mediates the interactions with adsorbate molecules. In order to study the adsorption of biomolecules on titanium in a realistic fashion, we first build up a model of an oxidized Ti surface in contact with liquid water by means of extensive first-principles molecular dynamics simulations. Taking the obtained structure as reference, we then develop a classical potential to model the Ti/TiOx/water interface. This is based on the mapping with Coulomb and Lennard-Jones potentials of the adsorption energy landscape of single water and ammonia molecules on the rutile TiO2(110) surface. The interactions with arbitrary organic molecules are obtained via standard combination rules to established biomolecular force fields. The transferability of our potential to the case of organic molecules adsorbing on the oxidized Ti surface is checked by comparing the classical potential energy surfaces of representative systems to quantum mechanical results at the level of density functional theory. Moreover, we calculate the heat of immersion of the TiO2 rutile surface and the detachment force of a single tyrosine residue from steered molecular dynamics simulations, finding good agreement with experimental reference data in both cases. As a first application, we study the adsorption behavior of the Arg-Gly-Asp (RGD) peptide on the oxidized titanium surface, focusing particularly on the calculation of the free energy of desorption.

Polanyi's tacit knowing and the relevance of epistemology to clinical medicine.

Science.gov (United States)

Henry, Stephen G

2010-04-01

Most clinicians take for granted a simple, reductionist understanding of medical knowledge that is at odds with how they actually practice medicine; routine medical decisions incorporate more complicated kinds of information than most standard accounts of medical reasoning suggest. A better understanding of the structure and function of knowledge in medicine can lead to practical improvements in clinical medicine. This understanding requires some familiarity with epistemology, the study of knowledge and its structure, in medicine. Michael Polanyi's theory of tacit knowing is advanced as the basis for developing a more accurate understanding of medical knowledge. Tacit knowing, which explores the taken-for-granted background knowledge that underlies all human knowing, is explained in detail with a focus on its relevance for clinical medicine. The implications of recognizing tacit knowing in medicine and medical decisions are discussed. These include the ability to explain the importance of the clinical encounter in medical practice, mechanisms for analysing patient and doctor as persons, and the need for humility given the uncertainty that the tacit dimension injects into all medical decisions. This more robust medical epistemology allows clinicians to better articulate the nature and importance of patient-centred care, to avoid pitfalls inherent in reductionist approaches to medical knowledge, and to think more clearly about the relationships between medicine and health care at the individual and population levels.

Doping as a means to probe the potential dependence of dopamine adsorption on carbon-based surfaces: A first-principles study

Science.gov (United States)

Aarva, Anja; Laurila, Tomi; Caro, Miguel A.

2017-06-01

In this work, we study the adsorption characteristics of dopamine (DA), ascorbic acid (AA), and dopaminequinone (DAox) on carbonaceous electrodes. Our goal is to obtain a better understanding of the adsorption behavior of these analytes in order to promote the development of new carbon-based electrode materials for sensitive and selective detection of dopamine in vivo. Here we employ density functional theory-based simulations to reach a level of detail that cannot be achieved experimentally. To get a broader understanding of carbonaceous surfaces with different morphological characteristics, we compare three materials: graphene, diamond, and amorphous carbon (a-C). Effects of solvation on adsorption characteristics are taken into account via a continuum solvent model. Potential changes that take place during electrochemical measurements, such as cyclic voltammetry, can also alter the adsorption behavior. In this study, we have utilized doping as an indirect method to simulate these changes by shifting the work function of the electrode material. We demonstrate that sp2- and sp3-rich materials, as well as a-C, respond markedly different to doping. Also the adsorption behavior of the molecules studied here differs depending on the surface material and the change in the surface potential. In all cases, adsorption is spontaneous, but covalent bonding is not detected in vacuum. The aqueous medium has a large effect on the adsorption behavior of DAox, which reaches its highest adsorption energy on diamond when the potential is shifted to more negative values. In all cases, inclusion of the solvent enhances the charge transfer between the slab and DAox. Largest differences in adsorption energy between DA and AA are obtained on graphene. Gaining better understanding of the behavior of the different forms of carbon when used as electrode materials provides a means to rationalize the observed complex phenomena taking place at the electrodes during electrochemical oxidation

A new analytical potential energy surface for the adsorption systemk CO/Cu(100)

NARCIS (Netherlands)

Marquardt, R.; Cuvelier, F.; Olsen, R.A.; Baerends, E.J.; Tremblay, J.C.; Saalfrank, P.

2010-01-01

Electronic structure data and analytical representations of the potential energy surface for the adsorption of carbon monoxide on a crystalline copper Cu(100) substrate are reviewed. It is found that a previously published and widely used analytical hypersurface for this process [J. C. Tully, M.

LEPS potential for H3 from force field data

International Nuclear Information System (INIS)

Varandas, A.J.C.

1979-01-01

A new potential energy surface for H 3 of the London--Eyring--Polanyi--Sato type has been obtained which reproduces the best available estimates for the geometry, classical barrier height, and quadratic force constants of the D/sub infinityh/ saddle point. Other attributes of the surface, e.g., minimum energy profile for the exchange process, spherically averaged potential V 0 , and leading anisotropic potential V 2 , are also shown to be in good agreement with the best available estimates. The simplicity of its functional form further commends it for future dynamical studies

Effects of van der Waals density functional corrections on trends in furfural adsorption and hydrogenation on close-packed transition metal surfaces

Science.gov (United States)

Liu, Bin; Cheng, Lei; Curtiss, Larry; Greeley, Jeffrey

2014-04-01

The hydrogenation of furfural to furfuryl alcohol on Pd(111), Cu(111) and Pt(111) is studied with both standard Density Functional Theory (DFT)-GGA functionals and with van der Waals-corrected density functionals. VdW-DF functionals, including optPBE, optB88, optB86b, and Grimme's method, are used to optimize the adsorption configurations of furfural, furfuryl alcohol, and related intermediates resulting from hydrogenation of furfural, and the results are compared to corresponding values determined with GGA functionals, including PW91 and PBE. On Pd(111) and Pt(111), the adsorption geometries of the intermediates are not noticeably different between the two classes of functionals, while on Cu(111), modest changes are seen in both the perpendicular distance and the orientation of the aromatic ring with respect to the planar surface. In general, the binding energies increase substantially in magnitude as a result of van der Waals contributions on all metals. In contrast, however, dispersion effects on the kinetics of hydrogenation are relatively small. It is found that activation barriers are not significantly affected by the inclusion of dispersion effects, and a Brønsted-Evans-Polanyi relationship developed solely from PW91 calculations on Pd(111) is capable of describing corresponding results on Cu(111) and Pt(111), even when the dispersion effects are included. Finally, the reaction energies and barriers derived from the dispersion-corrected and pure GGA calculations are used to plot simple potential energy profiles for furfural hydrogenation to furfuryl alcohol on the three considered metals, and an approximately constant downshift of the energetics due to the dispersion corrections is observed.

Role of spent shale in oil shale processing and the management of environmental residues. Final technical report, January 1979-May 1980

Energy Technology Data Exchange (ETDEWEB)

Hines, A.L.

1980-08-15

The adsorption of hydrogen sulfide on retorted oil shale was studied at 10, 25, and 60/sup 0/C using a packed bed method. Equilibrium isotherms were calculated from the adsorption data and were modeled by the Langmuir, Freundlich, and Polanyi equations. The isosteric heat of adsorption was calculated at three adsorbent loadings and was found to increase with increased loading. A calculated heat of adsorption less than the heat of condensation indicated that the adsorption was primarily due to Van der Waals' forces. Adsorption capacities were also found as a function of oil shale retorting temperature with the maximum uptake occurring on shale that was retorted at 750/sup 0/C.

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties.

Science.gov (United States)

Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

2016-03-11

GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5-11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm(3) g(-1) (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g(-1)) and P7 (1388.8 mg g(-1)) samples reveal that these two particular samples can absorb even more water than their own weights.

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

Science.gov (United States)

Sharma, Pankaj; Song, Ju-Sub; Han, Moon Hee; Cho, Churl-Hee

2016-01-01

GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5–11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm3 g−1 (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g−1) and P7 (1388.8 mg g−1) samples reveal that these two particular samples can absorb even more water than their own weights. PMID:26964638

The use of sugar and alcohol industry waste in the adsorption of potentially toxic metals.

Science.gov (United States)

Santos, Oseas Silva; Mendonça, André Gustavo Ribeiro; Santos, Josué Carinhanha Caldas; Silva, Amanda Paulina Bezerra; Costa, Silvanio Silverio Lopes; Oliveira, Luciana Camargo; Carmo, Janaina Braga; Botero, Wander Gustavo

2016-01-01

One of the waste products of the industrial process of the sugar and alcohol agribusiness is filter cake (FC). This waste product has high levels of organic matter, mainly proteins and lipids, and is rich in calcium, nitrogen, potassium and phosphorous. In this work we characterized samples of FC from sugar and alcohol industries located in sugarcane-producing regions in Brazil and assessed the adsorption of potentially toxic metals (Cu(II), Cd(II), Pb(II), Ni(II) and Cr(III)) by this waste in mono- and multi-elemental systems, seeking to use FC as an adsorbent in contaminated environments. The characterization of FCs showed significant differences between the samples and the adsorption studies showed retention of over 90% of potentially toxic metals. In a competitive environment (multi-metallic solution), the FC was effective in adsorbing all metals except lead, but less effective compared to the mono-metallic solution. These results show the potential for use of this residue as an adsorbent in contaminated environments.

Evaluation of the potential of red mud heat treated at 400 deg C in adsorption of reactive yellow 145 dye

International Nuclear Information System (INIS)

Rangueri, T.B.; Souza, K.C. de; Lima, V.F. de; Antunes, M.L.P.

2012-01-01

Red mud is the generic name for the industrial waste generated during the Bayer process. Storing this material can cause environmental damage and requires a large area for their disposal. Red mud has properties to be used in treatment of effluents. The red mud was dried and activated at 400°C. This work presents the characterization by pH, conductivity and zero charge potential of the red mud thermally activated. The assessment of adsorption capacity of this material to dye reactive Yellow 145 in pH 4 was done. The percentage of adsorption to concentrations of 500 mg/L of dye reaches 97%. This work presents results of adsorption isotherms, using the Langmuir model, and reaction kinetics. It is concluded that, in an acid medium, the red mud presents excellent potential of adsorption and could be an alternative material to absorb the Yellow 145 dye. (author)

Adsorption Properties and Potential Applications of Bamboo Charcoal: A Review

Directory of Open Access Journals (Sweden)

Isa S.S.M.

2016-01-01

Full Text Available Bamboo charcoal was produced by pyrolysis or carbonization process with extraordinary properties such as high conductivity, large surface area and adsorption property. These properties can be improved by activation process that can be done thermally or chemically. In this paper, carbonization and activation process of bamboo, its structural and adsorption properties will be presented. Herein, the adsorption properties of bamboo charcoal that has fully utilized in solar cell as the electrode, adsorbent for water purification and electromagnetic wave absorber are reviewed.

[Bidens maximowicziana's adsorption ability and remediation potential to lead in soils].

Science.gov (United States)

Wang, Hong-qi; Li, Hua; Lu, Si-jin

2005-11-01

Bidens maximowicziana's adsorption ability and remediation potential to lead were studied. The results show: (1) The Bidens maximowicziana has a strong adsorption to lead, the concentration of lead in plants increased linearly with the increase of lead concentration in soil. Then maximum concentration was 1509.3 mg x kg(-1) in roots and 2164.7 mg x kg(-1) in shoots when lead concentration in soil was 2000 mg x L(-1); (2) The lead concentration distribution order in the Bidens maximorwicziana is: leaf>stem>root>seed, which indicate that Bidens maximowicziana has a strong ability to transfer lead; (3) Uptaking ability differes in different vegetal periods. Maximum lead uptaking rate occured in the period of blooming for 40-60 days, in which daily uptake capacity was 15.81 mg x (kg x d)(-1) in roots and 19.83 mg x (kg x d)(-1) in shoots respectively. It can be concluded that Bidens maximowicziana appeares to be a moderate Pb accumulator making it suitable for phytoremediation of Pb contaminated soil.

Multicomponent Adsorption Model for Polar and Associating Mixtures

DEFF Research Database (Denmark)

Nesterov, Igor; Shapiro, Alexander; Kontogeorgis, Georgios M.

2015-01-01

of these problems could be due to the fact that the original MPTA assumes that a given adsorbent has the same adsorption capacity (for example, porous volume) for all the adsorbed substances and is adjusted simultaneously to many data. This is a simplified picture, as experimental data indicate that the adsorption......-Radushkevich-Astakhov potentials and the potentials directly restored from experimental data by solving the inverse problem. Application of the latter potentials Clearly demonstrates the importance of the difference in adsorption capacities. However, the quality of prediction of binary adsorption is similar for both potentials...

Nanoporous spongy graphene: Potential applications for hydrogen adsorption and selective gas separation

Energy Technology Data Exchange (ETDEWEB)

Kostoglou, Nikolaos, E-mail: nikolaos.kostoglou@stud.unileoben.ac.at [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus); Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, 8700 Leoben (Austria); Constantinides, Georgios [Research Unit for Nanostructured Materials Systems, Department of Mechanical Engineering and Materials Science and Engineering, Cyprus University of Technology, 3036 Lemesos (Cyprus); Charalambopoulou, Georgia; Steriotis, Theodore [National Center for Scientific Research Demokritos, Agia Paraskevi Attikis, 15310 Athens (Greece); Polychronopoulou, Kyriaki [Department of Mechanical Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); Li, Yuanqing; Liao, Kin [Department of Aerospace Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); Ryzhkov, Vladislav [Nanotube Production Department, Fibrtec Incorporation, TX, 75551 Atlanta (United States); Mitterer, Christian [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, 8700 Leoben (Austria); Rebholz, Claus, E-mail: claus@ucy.ac.cy [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus)

2015-12-01

In the present work, a nanoporous (pore width ~ 0.7 nm) graphene-based sponge-like material with large surface area (~ 350 m{sup 2}/g) was synthesized by wet chemical reduction of graphene oxide in combination with freeze-drying. Surface morphology and elemental composition were studied by scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy. Surface chemistry was qualitatively examined by Fourier-transform infrared spectroscopy, while the respective structure was investigated by X-ray diffraction analysis. Textural properties, including Brunauer–Emmet–Teller (BET) surface area, micropore volume and surface area as well as pore size distribution, were deduced from nitrogen gas adsorption/desorption data obtained at 77 K and up to 1 bar. Potential use of the spongy graphene for gas storage and separation applications was preliminarily assessed by low-pressure (0–1 bar) H{sub 2}, CO{sub 2} and CH{sub 4} sorption measurements at different temperatures (77, 273 and 298 K). The adsorption capacities for each gas were evaluated up to ~ 1 bar, the isosteric enthalpies of adsorption for CO{sub 2} (28–33 kJ/mol) and CH{sub 4} (30–38 kJ/mol) were calculated using the Clausius–Clapeyron equation, while the CO{sub 2}/CH{sub 4} gas selectivity (up to 95:1) was estimated using the Ideal Adsorbed Solution Theory (IAST). - Highlights: • Nanoporous sponge produced by chemical reduction of graphene oxide and freeze-drying • Characterization performed using SEM, EDS, TEM, FT-IR, BET and XRD methods • Gas storage performance evaluated towards H{sub 2}, CO{sub 2} and CH{sub 4} adsorption up to 1 bar • CO{sub 2} over CH{sub 4} gas selectivity estimated between 45 and 95 at 273 K using the IAST model.

Nanoporous spongy graphene: Potential applications for hydrogen adsorption and selective gas separation

International Nuclear Information System (INIS)

Kostoglou, Nikolaos; Constantinides, Georgios; Charalambopoulou, Georgia; Steriotis, Theodore; Polychronopoulou, Kyriaki; Li, Yuanqing; Liao, Kin; Ryzhkov, Vladislav; Mitterer, Christian; Rebholz, Claus

2015-01-01

In the present work, a nanoporous (pore width ~ 0.7 nm) graphene-based sponge-like material with large surface area (~ 350 m"2/g) was synthesized by wet chemical reduction of graphene oxide in combination with freeze-drying. Surface morphology and elemental composition were studied by scanning and transmission electron microscopy combined with energy dispersive X-ray spectroscopy. Surface chemistry was qualitatively examined by Fourier-transform infrared spectroscopy, while the respective structure was investigated by X-ray diffraction analysis. Textural properties, including Brunauer–Emmet–Teller (BET) surface area, micropore volume and surface area as well as pore size distribution, were deduced from nitrogen gas adsorption/desorption data obtained at 77 K and up to 1 bar. Potential use of the spongy graphene for gas storage and separation applications was preliminarily assessed by low-pressure (0–1 bar) H_2, CO_2 and CH_4 sorption measurements at different temperatures (77, 273 and 298 K). The adsorption capacities for each gas were evaluated up to ~ 1 bar, the isosteric enthalpies of adsorption for CO_2 (28–33 kJ/mol) and CH_4 (30–38 kJ/mol) were calculated using the Clausius–Clapeyron equation, while the CO_2/CH_4 gas selectivity (up to 95:1) was estimated using the Ideal Adsorbed Solution Theory (IAST). - Highlights: • Nanoporous sponge produced by chemical reduction of graphene oxide and freeze-drying • Characterization performed using SEM, EDS, TEM, FT-IR, BET and XRD methods • Gas storage performance evaluated towards H_2, CO_2 and CH_4 adsorption up to 1 bar • CO_2 over CH_4 gas selectivity estimated between 45 and 95 at 273 K using the IAST model

Assessment of adsorbate density models for numerical simulations of zeolite-based heat storage applications

International Nuclear Information System (INIS)

Lehmann, Christoph; Beckert, Steffen; Gläser, Roger; Kolditz, Olaf; Nagel, Thomas

2017-01-01

Highlights: • Characteristic curves fit for binderless Zeolite 13XBFK. • Detailed comparison of adsorbate density models for Dubinin’s adsorption theory. • Predicted heat storage densities robust against choice of density model. • Use of simple linear density models sufficient. - Abstract: The study of water sorption in microporous materials is of increasing interest, particularly in the context of heat storage applications. The potential-theory of micropore volume filling pioneered by Polanyi and Dubinin is a useful tool for the description of adsorption equilibria. Based on one single characteristic curve, the system can be extensively characterised in terms of isotherms, isobars, isosteres, enthalpies etc. However, the mathematical description of the adsorbate density’s temperature dependence has a significant impact especially on the estimation of the energetically relevant adsorption enthalpies. Here, we evaluate and compare different models existing in the literature and elucidate those leading to realistic predictions of adsorption enthalpies. This is an important prerequisite for accurate simulations of heat and mass transport ranging from the laboratory scale to the reactor level of the heat store.

Analysis of casein biopolymers adsorption to lignocellulosic biomass as a potential cellulase stabilizer.

Science.gov (United States)

Eckard, Anahita Dehkhoda; Muthukumarappan, Kasiviswanathan; Gibbons, William

2012-01-01

Although lignocellulosic materials have a good potential to substitute current feedstocks used for ethanol production, conversion of these materials to fermentable sugars is still not economical through enzymatic hydrolysis. High cost of cellulase has prompted research to explore techniques that can prevent from enzyme deactivation. Colloidal proteins of casein can form monolayers on hydrophobic surfaces that alleviate the de-activation of protein of interest. Scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), capillary electrophoresis (CE), and Kjeldahl and BSA protein assays were used to investigate the unknown mechanism of action of induced cellulase activity during hydrolysis of casein-treated biomass. Adsorption of casein to biomass was observed with all of the analytical techniques used and varied depending on the pretreatment techniques of biomass. FT-IR analysis of amides I and II suggested that the substructure of protein from casein or skim milk were deformed at the time of contact with biomass. With no additive, the majority of one of the cellulase mono-component, 97.1 ± 1.1, was adsorbed to CS within 24 h, this adsorption was irreversible and increased by 2% after 72 h. However, biomass treatment with skim-milk and casein reduced the adsorption to 32.9% ± 6.0 and 82.8% ± 6.0, respectively.

Arsenic Adsorption Equilibrium Concentration and Adsorption Rate of Activated Carbon Coated with Ferric-Aluminum Hydroxides

Science.gov (United States)

Zhang, M.; Sugita, H.; Oguma, T.; Hara, J.; Takahashi, S.

2015-12-01

In some areas of developing countries, ground or well water contaminated with arsenic has been reluctantly used as drinking water. It is highly desirable that effective and inexpensive arsenic removal agents should be developed and provided to reduce the potential health risk. Previous studies demonstrated that activated carbon coated with ferric-aluminum hydroxides (Fe-Al-C) has high adsorptive potential for removal of arsenic. In this study, a series of experiments using Fe-Al-C were carried to discuss adsorption equilibrium time, adsorption equilibrium concentration and adsorption rate of arsenic for Fe-Al-C. Fe-Al-C used in this study was provided by Astec Co., Ltd. Powder reagent of disodium hydrogen arsenate heptahydrate was dissolved into ion-exchanged water. The solution was then further diluted with ion-exchanged water to be 1 and 10 mg/L as arsenic concentration. The pH of the solution was adjusted to be around 7 by adding HCl and/or NaOH. The solution was used as artificial arsenic contaminated water in two types of experiments (arsenic adsorption equilibrium and arsenic adsorption rate tests). The results of the arsenic equilibrium tests were showed that a time period of about 3 days to reach apparent adsorption equilibrium for arsenic. The apparent adsorption equilibrium concentration and adsorbed amount of arsenic on Fe-Al-C adsorbent could be estimated by application of various adsorption isotherms, but the distribution coefficient of arsenic between solid and liquid varies with experimental conditions such as initial concentration of arsenic and addition concentration of adsorbent. An adsorption rate equation that takes into account the reduction in the number of effective adsorption sites on the adsorbent caused by the arsenic adsorption reaction was derived based on the data obtained from the arsenic adsorption rate tests.

Adsorption of simple molecules on clean metal surfaces

International Nuclear Information System (INIS)

Na Lamphun, O.-A.

1980-06-01

The adsorption of nitric oxide, oxygen, krypton and xenon on evaporated tungsten, nickel and iron films is studied. The theoretical and experimental aspects of adsorption are reviewed, a preliminary study of adsorption by the volumetric method is presented, surface potential and sticking probability studies of adsorption using ion gauges are investigated and an analysis of residual gases, sticking probability and surface potential studies using quadrupole mass spectrometry, given. (author)

Comparative potential of black tea leaves waste to granular activated carbon in adsorption of endocrine disrupting compounds from aqueous solution

Directory of Open Access Journals (Sweden)

A.O. Ifelebuegu

2015-07-01

Full Text Available The adsorption properties and mechanics of selected endocrine disrupting compounds; 17 β-estradiol, 17 α – ethinylestradiol and bisphenol A on locally available black tea leaves waste and granular activated carbon were investigated. The results obtained indicated that the kinetics of adsorption were pH, adsorbent dose, contact time and temperature dependent with equilibrium being reached at 20 to 40 minutes for tea leaves waste and 40 to 60 minutes for granular activated compound. Maximum adsorption capacities of 3.46, 2.44 and 18.35 mg/g were achieved for tea leaves waste compared to granular activated compound capacities of 4.01, 2.97 and 16.26 mg/g for 17 β- estradiol, 17 α-ethinylestradiol and bisphenol A respectively. Tea leaves waste adsorption followed pseudo-first order kinetics while granular activated compound fitted better to the pseudo-second order kinetic model. The experimental isotherm data for both tea leaves waste and granular activated compound showed a good fit to the Langmuir, Freundlich and Temkin isotherm models with the Langmuir model showing the best fit. The thermodynamic and kinetic data for the adsorption indicated that the adsorption process for tea leaves waste was predominantly by physical adsorption while the granular activated compound adsorption was more chemical in nature. The results have demonstrated the potential of waste tea leaves for the adsorptive removal of endocrine disrupting compounds from water.

Evaluation of the potential of volatile organic compound (di-methyl benzene) removal using adsorption on natural minerals compared to commercial oxides

Energy Technology Data Exchange (ETDEWEB)

Zaitan, Hicham, E-mail: hicham.zaitan@usmba.ac.ma [Laboratory LCMC, Faculty of Sciences and Techniques, University Sidi Mohamed BenAbdellah, B.P. 2202, Fez (Morocco); Korrir, Abdelhamid; Chafik, Tarik [Laboratory LGCVR, Faculty of Sciences and Techniques, University Abdelmalek Essaadi, B.P. 416, Tangier (Morocco); Bianchi, Daniel [Institut de Recherche sur la Catalyse et l’Environnement de Lyon (IRCELYON), UMR 5256 CNRS, University Claude Bernard Lyon I, Bat. Chevreul, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne (France)

2013-11-15

Highlights: • The adsorption of dMB on natural minerals and commercial oxides was evaluated. • The adsorption capacities were discussed considering the adsorbents cost and the bed size. • The adsorption capacity of bentonite is higher than other adsorbents. • Langmuir model provide best correlation of the experimental data. • The isotherms data allow determination of isosteric heat of adsorption. -- Abstract: This study is dedicated to the investigation of the potential of volatile organic compounds (VOC) adsorption over low cost natural minerals (bentonite and diatomite). The performances of these solids, in terms of adsorption/desorption properties, were compared to commercial adsorbents, such as silica, alumina and titanium dioxide. The solids were first characterized by different physico-chemical methods and di-methyl benzene (dMB) was selected as model VOC pollutant for the investigation of adsorptive characteristics. The experiments were carried out with a fixed bed reactor under dynamic conditions using Fourier Transform InfraRed spectrometer to measure the evolution of dMB concentrations in the gaseous stream at the outlet of the reactor. The measured breakthrough curves yields to adsorbed amounts at saturation that has been used to obtain adsorption isotherms. The latters were used for determination of the heat involved in the adsorption process and estimation of its values using the isosteric method. Furthermore, the performances of the studied materials were compared considering the adsorption efficiency/cost ratio.

Evaluation of the potential of volatile organic compound (di-methyl benzene) removal using adsorption on natural minerals compared to commercial oxides

International Nuclear Information System (INIS)

Zaitan, Hicham; Korrir, Abdelhamid; Chafik, Tarik; Bianchi, Daniel

2013-01-01

Highlights: • The adsorption of dMB on natural minerals and commercial oxides was evaluated. • The adsorption capacities were discussed considering the adsorbents cost and the bed size. • The adsorption capacity of bentonite is higher than other adsorbents. • Langmuir model provide best correlation of the experimental data. • The isotherms data allow determination of isosteric heat of adsorption. -- Abstract: This study is dedicated to the investigation of the potential of volatile organic compounds (VOC) adsorption over low cost natural minerals (bentonite and diatomite). The performances of these solids, in terms of adsorption/desorption properties, were compared to commercial adsorbents, such as silica, alumina and titanium dioxide. The solids were first characterized by different physico-chemical methods and di-methyl benzene (dMB) was selected as model VOC pollutant for the investigation of adsorptive characteristics. The experiments were carried out with a fixed bed reactor under dynamic conditions using Fourier Transform InfraRed spectrometer to measure the evolution of dMB concentrations in the gaseous stream at the outlet of the reactor. The measured breakthrough curves yields to adsorbed amounts at saturation that has been used to obtain adsorption isotherms. The latters were used for determination of the heat involved in the adsorption process and estimation of its values using the isosteric method. Furthermore, the performances of the studied materials were compared considering the adsorption efficiency/cost ratio

Analysis of Casein Biopolymers Adsorption to Lignocellulosic Biomass as a Potential Cellulase Stabilizer

Directory of Open Access Journals (Sweden)

Anahita Dehkhoda Eckard

2012-01-01

Full Text Available Although lignocellulosic materials have a good potential to substitute current feedstocks used for ethanol production, conversion of these materials to fermentable sugars is still not economical through enzymatic hydrolysis. High cost of cellulase has prompted research to explore techniques that can prevent from enzyme deactivation. Colloidal proteins of casein can form monolayers on hydrophobic surfaces that alleviate the de-activation of protein of interest. Scanning electron microscope (SEM, fourier transform infrared spectroscopy (FT-IR, capillary electrophoresis (CE, and Kjeldahl and BSA protein assays were used to investigate the unknown mechanism of action of induced cellulase activity during hydrolysis of casein-treated biomass. Adsorption of casein to biomass was observed with all of the analytical techniques used and varied depending on the pretreatment techniques of biomass. FT-IR analysis of amides I and II suggested that the substructure of protein from casein or skim milk were deformed at the time of contact with biomass. With no additive, the majority of one of the cellulase mono-component, 97.1 ± 1.1, was adsorbed to CS within 24 h, this adsorption was irreversible and increased by 2% after 72 h. However, biomass treatment with skim-milk and casein reduced the adsorption to 32.9% ± 6.0 and 82.8% ± 6.0, respectively.

Analysis of Casein Biopolymers Adsorption to Lignocellulosic Biomass as a Potential Cellulase Stabilizer

Science.gov (United States)

Eckard, Anahita Dehkhoda; Muthukumarappan, Kasiviswanathan; Gibbons, William

2012-01-01

Although lignocellulosic materials have a good potential to substitute current feedstocks used for ethanol production, conversion of these materials to fermentable sugars is still not economical through enzymatic hydrolysis. High cost of cellulase has prompted research to explore techniques that can prevent from enzyme deactivation. Colloidal proteins of casein can form monolayers on hydrophobic surfaces that alleviate the de-activation of protein of interest. Scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), capillary electrophoresis (CE), and Kjeldahl and BSA protein assays were used to investigate the unknown mechanism of action of induced cellulase activity during hydrolysis of casein-treated biomass. Adsorption of casein to biomass was observed with all of the analytical techniques used and varied depending on the pretreatment techniques of biomass. FT-IR analysis of amides I and II suggested that the substructure of protein from casein or skim milk were deformed at the time of contact with biomass. With no additive, the majority of one of the cellulase mono-component, 97.1 ± 1.1, was adsorbed to CS within 24 h, this adsorption was irreversible and increased by 2% after 72 h. However, biomass treatment with skim-milk and casein reduced the adsorption to 32.9% ± 6.0 and 82.8% ± 6.0, respectively. PMID:23118515

Adsorption of aliphatic alcohols on ruthenium

International Nuclear Information System (INIS)

Shapovalova, L.B.; Zakumbaeva, G.D.

1977-01-01

The adsorption is studied of allyl-, propyl- and propargyl alcohols on a ruthenium catalyst-electrode at 20, 30 and 40 deg C in H 2 SO 4 in helium. Above adsorption has been found to grow with increased concentration of the alcohols in the solution. In solutions with the same concentration, propargyl alcohol has been noted to show highest sorptive capacity, followed by that of allyl- and propyl alcohols. With variations in the ruthenium electrode potential, alcohol adsorption occurs via maximum at potential = 0.18

The adsorption of argon on ZnO at 77K

Science.gov (United States)

Marinelli, Francis; Grillet, Yves; Pellenq, Roland J.-M.

We have studied the adsorption of argon onto ZnO surfaces at 77K by means of quasiequilibrium adsorption volumetry coupled with high resolution microcalorimetry and Grand Canonical Monte-Carlo (GCMC) simulations. The adsorbate/surface adsorption potential function (PN type) used in the simulations, was determined on the basis of ab initio calculations (corrected for dispersion interactions). The first aspect of this work was to test the ability of a standard solid-state Hartree-Fock technique coupled with a perturbative semiempirical approach in deriving a reliable adsorption potential function. The dispersion part of the adsorbate/surface interatomic potential was derived by using perturbation theory-based equations while the repulsive and induction interactions were derived from periodic HartreeFock (CRYSTAL92) calculations. GCMC simulations based on this adsorption potential allow one to calculate adsorption isotherms and isosteric heat versus loading curves as well as singlet distribution functions at 77K for each type of ZnO (neutral and polar) faces. The combined analysis of the simulation data for all surfaces gives a good insight of the adsorption mechanism of argon onto ZnO surfaces at 77K in agreement with experiment. As far as neutral surfaces are concerned, it is shown that adsorption first takes place within the 'troughs' which cover ZnO neutral surfaces. At low chemical potentials, these semi-channels are preferential adsorption sites in which we could detect a nearly one-dimensional adsorbate freezing in a commensurate phase at 77K. The polar O faces are the most favourable surfaces for adsorption at higher chemical potentials.

Adsorption of histones on natural polysaccharides: The potential as agent for multiple organ failure in sepsis.

Science.gov (United States)

Isobe, Takashi; Kofuji, Kyoko; Okada, Kenji; Fujimori, Junya; Murata, Mikio; Shigeyama, Masato; Hanioka, Nobumitsu; Murata, Yoshifumi

2016-03-01

Histones are intracellular proteins that are structural elements of nuclear chromatin and regulate gene transcription. However, the extracellular histones released in response to bacterial challenges have been identified as mediators contributing to endothelial dysfunction, organ failure, and death during sepsis. In the present study, the adsorption of histones as well as plasma proteins (α1-acid glycoprotein (AGP), albumin, and γ-globulin) on alginic acid, pectin, dextran, and chitosan was examined in order to evaluate the potential of natural polysaccharides as therapeutic agents for multiple organ failure in sepsis. Alginic acid and pectin strongly adsorbed histones, whereas the adsorption abilities of dextran and chitosan toward histones were very low or negligible. Among the natural polysaccharides examined, only alginic acid did not adsorb any of the plasma proteins. These results demonstrated that alginic acid strongly adsorbed histones, but not plasma proteins; therefore, it has potential as a candidate drug for the treatment of multiple organ failure in sepsis. Copyright © 2015 Elsevier B.V. All rights reserved.

adsorption, eosin, humic, peat

OpenAIRE

anshar, andi muhammad

2015-01-01

Eosin is one of the dyes commonly used in the industry and has the potential to cause pollution of the water environment. The Eosin pollution treatment methods used in this study was the adsorption method using humin fraction obtained from the peat land comes from Kalimantan. From the research data showed that the adsorption of eosin in humin result of washing with HCl / HF optimum at pH 4 and a contact time of 60 minutes with the adsorption-order rate was 8,4 x 10-3 min-1

Chitosan supramolecularly cross linked with trimesic acid - Facile synthesis, characterization and evaluation of adsorption potential for chromium(VI).

Science.gov (United States)

Bhatt, Ronak; Sreedhar, B; Padmaja, P

2017-11-01

A facile synthesis of Chitosan Supramolecularly cross-linked with Trimesic Acid (CTMA) is reported in this work. The adsorption potential of CTMA for removal of hexavalent chromium was evaluated and the influence of pH, temperature, contact time and adsorbent dose on the adsorption process was investigated. The experimental results showed that CTMA could efficiently adsorb Cr 6+ and partially reduce it to the less toxic Cr 3+ state. The maximum adsorption capacity of CTMA for Cr 6+ was found to be 129.53mg/g at pH 2.0. CTMA and chromium loaded CTMA were characterised by FT-IR, Raman, TGA-DSC, SEM-EDX, XRD, ESR and XPS spectroscopic techniques. Chitosan was observed to be cross- linked with TMA via ionic, hydrogen bonding and pi-pi supramolecular interactions while adsorption of chromium onto CTMA was by electrostatic forces and hydrogen bonding. From the observed results it was evident that CTMA was successfully applied for simultaneous removal of chromium, lead and iron from chrome plating effluent. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of transition metal-doped Ni(211) for CO dissociation: Insights from DFT calculations

Energy Technology Data Exchange (ETDEWEB)

Yang, Kuiwei; Zhang, Minhua [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Yu, Yingzhe, E-mail: yzhyu@tju.edu.cn [Key Laboratory for Green Chemical Technology of Ministry of Education, R& D Center for Petrochemical Technology, Tianjin University, Tianjin 300072 (China)

2017-03-31

Highlights: • Doping the step edge of Ni(211) with Fe or Ru observably enhances CO dissociation. • Rh doping is unfavorable for CO activation both kinetically and thermodynamically. • Two neat linear relations are proposed besides the Brønsted–Evans–Polanyi relation. • The differences of CO adsorption are rationalized via the Blyholder model. - Abstract: Density functional theory slab calculations were performed to investigate the adsorption and dissociation of CO over pure and M-doped Ni(211) (M = Fe, Co, Ru and Rh) with the aim to elucidate the effect of transition metal doping for CO activation. Doping the step edge of Ni(211) with Fe, Co and Ru is found to enhance the binding of CO in the initial state (IS) (in the sequence by the improvement degree: Fe > Ru > Co) as well as the co-adsorption of C and O in the final state (FS) (Ru > Fe > Co). In contrast, Rh doping is unfavorable both in the IS and in the FS. Analysis of the overall potential energy surfaces (PES) suggests CO dissociation is facilitated by Fe, Ru and Co doping both kinetically and thermodynamically, wherein Fe and Ru behave extraordinary. Interestingly, Fe substitute is slightly superior to Ru in kinetics whereas the contrary is the case in thermodynamics. Rh doping elevates the energy height from 0.97 eV on Ni(211) to 1.32 eV and releases 0.39 eV less heat relative to Ni(211), again manifesting a negative effect. Besides the classical Brønsted–Evans–Polanyi relationship, we put forward another two neat linear relations, which can well describe the feature of CO dissociation. The differences of CO adsorption and activation in the IS over pure and doped Ni(211) surfaces are rationalized via electronic structure analysis. The findings presented herein are expected to provide theoretical guidance for catalyst design and optimization in relevant processes.

Adsorption of ions by colloids in electrolyte solutions

International Nuclear Information System (INIS)

Kallay, N.

1977-01-01

The adsorption isotherm for ionic adsorption by colloid particles was evaluated. The adsorption process was treated as the reaction between colloid particles and ions. The colloid particle has been here considered as a reaction entity. The possibility of the surface potential determination was presented. The analyses of the experimental data showed, that (at electrolyte concentration higher than the critical coagulation one) the surface potential reaches its zero value

New developments for localized adsorption

International Nuclear Information System (INIS)

Boudh-hir, M.E.

1989-02-01

Using the diagrammatic expansion, new developments for localized adsorption are found. It is proved that the correlations in the system, in the absence of the attractive site potential, and the periodicity of the sites play a fundamental role in the adsorption phenomena. 14 refs, 2 figs, 2 tabs

Relationship between the adsorption species of cesium and radiocesium interception potential in soils and minerals: an EXAFS study

International Nuclear Information System (INIS)

Fan, Qiaohui; Yamaguchi, Noriko; Tanaka, Masato; Tsukada, Hirofumi; Takahashi, Yoshio

2014-01-01

This study examined the radiocesium (RCs) interception potential (RIP), cation exchange capacity (CEC), total organic carbon (TOC) content, and adsorption species in soils and minerals by using extended X-ray absorption fine structure (EXAFS) spectroscopy. The RIP related to Cs + adsorption by frayed-edge site (FES) has often been used to measure the mobility and bioavailability of RCs in the environment. This study found that the presence of organic matter (OM) can reduce RIP to a certain extent. The adsorption amount (=Q T ) in soil was obviously correlated to RIP at a small [Cs + ] region, whereas a linear relationship between Q T and CEC was observed at a large [Cs + ] region. Both the inner-sphere (IS) and outer-sphere (OS) complexes of Cs + were observed through EXAFS at a molecular scale. The linear correlation between log (RIP/CEC) and the ratio of the coordination number (CN) of IS (=CN IS ) and OS (=CN OS ) complexes noted as CN IS /(CN IS + CN OS ) suggested that the ratio of CN is very sensitive to Cs + adsorption species with variable RIP and CEC. The adsorption species of Cs + in soil was mainly dependent on the clay mineral content of soil. RIP was affected not only by FES but also by other strong adsorption sites, such as the interlayers and cavities identified as the IS complex in EXAFS analysis. Findings indicated that the EXAFS approach is a powerful and efficient tool to explore the behavior of Cs + in a given environment. - Highlights: • The relationship of Cs + species on soils and minerals and RIP was firstly clarified in this study. • Coordination number of Cs + was very sensitive to Cs + adsorption species with variable RIP and CEC. • This finding can be used as a basis for understanding of Cs + behavior in nature

Determination of coalbed methane potential and gas adsorption capacity in Western Kentucky coals

Science.gov (United States)

Mardon, S.M.; Takacs, K.G.; Hower, J.C.; Eble, C.F.; Mastalerz, Maria

2006-01-01

The Illinois Basin has not been developed for Coalbed Methane (CBM) production. It is imperative to determine both gas content and other parameters for the Kentucky portion of the Illinois Basin if exploration is to progress and production is to occur in this area. This research is part of a larger project being conducted by the Kentucky Geological Survey to evaluate the CBM production of Pennsylvanian-age western Kentucky coals in Ohio, Webster, and Union counties using methane adsorption isotherms, direct gas desorption measurements, and chemical analyses of coal and gas. This research will investigate relationships between CBM potential and petrographic, surface area, pore size, and gas adsorption isotherm analyses of the coals. Maceral and reflectance analyses are being conducted at the Center for Applied Energy Research. At the Indiana Geological Survey, the surface area and pore size of the coals will be analyzed using a Micrometrics ASAP 2020, and the CO2 isotherm analyses will be conducted using a volumetric adsorption apparatus in a water temperature bath. The aforementioned analyses will be used to determine site specific correlations for the Kentucky part of the Illinois Basin. The data collected will be compared with previous work in the Illinois Basin and will be correlated with data and structural features in the basin. Gas composition and carbon and hydrogen isotopic data suggest mostly thermogenic origin of coalbed gas in coals from Webster and Union Counties, Kentucky, in contrast to the dominantly biogenic character of coalbed gas in Ohio County, Kentucky.

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

Directory of Open Access Journals (Sweden)

Qing Chen

2017-01-01

Full Text Available Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.

Perchlorate adsorption and desorption on activated carbon and anion exchange resin.

Science.gov (United States)

Yoon, In-Ho; Meng, Xiaoguang; Wang, Chao; Kim, Kyoung-Woong; Bang, Sunbaek; Choe, Eunyoung; Lippincott, Lee

2009-05-15

The mechanisms of perchlorate adsorption on activated carbon (AC) and anion exchange resin (SR-7 resin) were investigated using Raman, FTIR, and zeta potential analyses. Batch adsorption and desorption results demonstrated that the adsorption of perchlorate by AC and SR-7 resin was reversible. The reversibility of perchlorate adsorption by the resin was also proved by column regeneration test. Solution pH significantly affected perchlorate adsorption and the zeta potential of AC, while it did not influence perchlorate adsorption and the zeta potential of resin. Zeta potential measurements showed that perchlorate was adsorbed on the negatively charged AC surface. Raman spectra indicated the adsorption resulted in an obvious position shift of the perchlorate peak, suggesting that perchlorate was associated with functional groups on AC at neutral pH through interactions stronger than electrostatic interaction. The adsorbed perchlorate on the resin exhibited a Raman peak at similar position as the aqueous perchlorate, indicating that perchlorate was adsorbed on the resin through electrostatic attraction between the anion and positively charged surface sites.

Analysis of Multicomponent Adsorption Close to a Dew Point

DEFF Research Database (Denmark)

Shapiro, Alexander; Stenby, Erling Halfdan

1998-01-01

We develop the potential theory of multicomponent adsorption close to a dew point. The approach is based on an asymptotic adsorption equation (AAE) which is valid in a vicinity of the dew point. By this equation the thickness of the liquid film is expressed through thermodynamic characteristics...... and the direct calculations, even if the mixture is not close to a dew point.Key Words: adsorption; potential theory; multicomponent; dew point....

Selective adsorption of bovine hemoglobin on functional TiO2 nano-adsorbents: surface physic-chemical properties determined adsorption activity

Science.gov (United States)

Guo, Shiguang; Zhang, Jianghua; Shao, Mingxue; Zhang, Xia; Liu, Yufeng; Xu, Junli; Meng, Hao; Han, Yide

2015-04-01

Surface functionalized nanoparticles are efficient adsorbents which have shown good potential for protein separation. In this work, we chose two different types of organic molecules, oleic acid (OA) and 3-glycidoxypropyltrimethoxy silane (GPTMS), to functionalize the surface of TiO2 nanoparticles, and we studied the effects of this modification on their surface physicochemical properties in correlation with their selective adsorption of proteins. The results showed that the surface zeta potential and the surface water wettability of the modified TiO2 were significantly changed in comparison with the original TiO2 nanoparticles. The adsorption activities of bovine hemoglobin (BHb) and bovine serum albumin (BSA) on these functionalized TiO2 samples were investigated under different conditions, including pH values, contact time, ion strength, and initial protein concentration. In comparison with the non-specific adsorption of original TiO2, however, both the OA-TiO2 and GPTMS-TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at the same time. Using a binary protein mixture as the adsorption object, a higher separation factor (SF) was obtained for OA-TiO2 under optimum conditions. The different adsorption activities of BHb and BSA on the modified TiO2 were correlated with different interactions at the protein/solid interface, and the chemical force as well as the electrostatic force played an important role in the selective adsorption process.

A review on adsorption refrigeration technology and adsorption deterioration in physical adsorption systems

Energy Technology Data Exchange (ETDEWEB)

Wang, D.C.; Li, Y.H. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Li, D.; Zhang, J.P. [College of Electromechanical Engineering, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Xia, Y.Z. [Laboratory of Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China)

2010-01-15

As one kind of environmentally friendly refrigeration, the adsorption refrigeration has attracted many attentions in resent decades. This paper introduces the researches of adsorption refrigeration systems with the commonly used working pairs, advanced adsorption cycles, heat and mass transfer enhancement and attempts of adsorption refrigeration applications. Poor heat and mass transfer problem is a bottleneck to prevent the improvements of the adsorption refrigeration technique. Two ways to enhance the heat and mass transfer are discussed in this paper. The adsorption deterioration of adsorbent, another obstacle to physical adsorption refrigeration applications, is also pointed out. And the possible reasons and the possible methods are analyzed. (author)

Phosphate adsorption from wastewater using zirconium (IV) hydroxide: Kinetics, thermodynamics and membrane filtration adsorption hybrid system studies.

Science.gov (United States)

Johir, M A H; Pradhan, M; Loganathan, P; Kandasamy, J; Vigneswaran, S

2016-02-01

Excessive phosphate in wastewater should be removed to control eutrophication of water bodies. The potential of employing amorphous zirconium (Zr) hydroxide to remove phosphate from synthetic wastewater was studied in batch adsorption experiments and in a submerged membrane filtration adsorption hybrid (MFAH) reactor. The adsorption data satisfactorily fitted to Langmuir, pseudo-first order and pseudo-second order models. Langmuir adsorption maxima at 22 °C and pHs of 4.0, 7.1, and 10.0 were 30.40, 18.50, and 19.60 mg P/g, respectively. At pH 7.1 and temperatures of 40 °C and 60 °C, they were 43.80 and 54.60 mg P/g, respectively. The thermodynamic parameters, ΔG° and ΔS° were negative and ΔH° was positive. FTIR, zeta potential and competitive phosphate, sulphate and nitrate adsorption data showed that the mechanism of phosphate adsorption was inner-sphere complexation. In the submerged MFAH reactor experiment, when Zr hydroxide was added at doses of 1-5 g/L once only at the start of the experiment, the removal of phosphate from 3 L of wastewater containing 10 mg P/L declined after 5 h of operation. However, when Zr hydroxide was repeatedly added at 5 g/L dose every 24 h, satisfactory removal of phosphate was maintained for 3 days. Copyright © 2015 Elsevier Ltd. All rights reserved.

High Pressure Multicomponent Adsorption in Porous Media

DEFF Research Database (Denmark)

Shapiro, Alexander; Stenby, Erling Halfdan

1999-01-01

We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent fi...... close to a dew point. This equation (asymptotic adsorption equation, AAE) is a first order approximation with regard to the distance from a phase envelope....

Effects of polyethyleneimine adsorption on rheology of bentonite ...

Indian Academy of Sciences (India)

Unknown

XRD, zeta potential and adsorption studies were done together with rheological .... trokinetics experiments on Balikesir bentonite samples. For this reason, the ... rence between apparent and true adsorption rates, and hence swelling of clays ...

Adsorption behavior of Am(III) on granite

International Nuclear Information System (INIS)

Zhang Yingjie; Feng Xiaogui; Liang Junfu; Chen Jing; Su Rui; Wang Ju; Liu Chunli

2009-01-01

The adsorption behavior of Am(III) on granite (sampled from drilling well BS01 at Beishan (BS) area--a potential candidate site for China's high-level radioactive waste repository, the granite sample's depth about 300 m) was studied in BS03 well groundwater by a batch technique at (25±1) degree C. The influences of pH, sulphate ion, total carbonate ion, humic acid, and concentration of the Am(III) on the adsorption behavior were also studied, and the possible adsorption mechanism was discussed. Experimental results show that the adsorption distribution rate of Am(III) on granite increases with increasing pH of aqueous phase. The chemical composition of the groundwater is the main factor which influences the species of Am(III) and adsorption behavior. The adsorption mechanism of Am(III) on granite is surface complexation. The adsorption isotherm of Am(III) on granite can be described by Freundlich's equation. (authors)

Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential

Science.gov (United States)

Tournassat, C.; Tinnacher, R. M.; Grangeon, S.; Davis, J. A.

2018-01-01

The prediction of U(VI) adsorption onto montmorillonite clay is confounded by the complexities of: (1) the montmorillonite structure in terms of adsorption sites on basal and edge surfaces, and the complex interactions between the electrical double layers at these surfaces, and (2) U(VI) solution speciation, which can include cationic, anionic and neutral species. Previous U(VI)-montmorillonite adsorption and modeling studies have typically expanded classical surface complexation modeling approaches, initially developed for simple oxides, to include both cation exchange and surface complexation reactions. However, previous models have not taken into account the unique characteristics of electrostatic surface potentials that occur at montmorillonite edge sites, where the electrostatic surface potential of basal plane cation exchange sites influences the surface potential of neighboring edge sites ('spillover' effect). A series of U(VI) - Na-montmorillonite batch adsorption experiments was conducted as a function of pH, with variable U(VI), Ca, and dissolved carbonate concentrations. Based on the experimental data, a new type of surface complexation model (SCM) was developed for montmorillonite, that specifically accounts for the spillover effect using the edge surface speciation model by Tournassat et al. (2016a). The SCM allows for a prediction of U(VI) adsorption under varying chemical conditions with a minimum number of fitting parameters, not only for our own experimental results, but also for a number of published data sets. The model agreed well with many of these datasets without introducing a second site type or including the formation of ternary U(VI)-carbonato surface complexes. The model predictions were greatly impacted by utilizing analytical measurements of dissolved inorganic carbon (DIC) concentrations in individual sample solutions rather than assuming solution equilibration with a specific partial pressure of CO2, even when the gas phase was

Some properties of solid helium and helium nanoclusters using the effective HFD-like interaction potential: Adsorption and desorption inside carbon nanotube

Science.gov (United States)

Abbaspour, M.; Akbarzadeh, H.; Banihashemi, S. Z.; Sotoudeh, A.

2018-02-01

We have calculated the zero equation of state of solid helium using a two-body Hartree-Fock dispersion (HFD)-like potential from molecular dynamics (MD) simulation. To take many-body forces into account, our simple and accurate empirical expression is used with the HFD-like potential without requiring an expensive three-body calculation. This potential model also includes the quantum effects for helium at low temperatures. The results indicate that our effective HFD-like potential improves the prediction of the classical two-body results to get better agreement with experiment than many other two-body and three-body potentials of helium reported in the literature. We have also simulated the adsorption and desorption processes of the (He)55, (He)147, (He)309, (He)561, and (He)923 icosahedral nanoclusters confined into the different armchair and zigzag CNTs from 0 to 50 K using our effective model. We have observed an interesting phenomenon at 0 K for helium. The nanoclusters adsorb to the inner CNT wall as a melting process. But, the heavier noble gas clusters (such as Ne and Xe) show the different behavior than the He clusters. They form a multilayered solid structure into the CNT at zero temperature and adsorb into the inner wall of the CNT at higher temperatures. Our results for He clusters show that the absolute value of the adsorption energy increases as the size of the nanocluster increases. The desorption process begins at a certain temperature and represents itself by a jump in the configurational energy values. We have also investigated the structural and dynamical properties of the confined helium nanoclusters during the adsorption and desorption processes at different temperatures.

Molecular dynamics simulation investigations of H2/D2 dissocitive chemisorption dynamics on Cun(n=13-14) Rigid/nonrigid clusters

International Nuclear Information System (INIS)

Elzein, N.

2004-01-01

In this work with a use of molecular dynamic simulations we have reported the results of a quasiclassical simulation study of the interaction of H2/(D2) with Cu N (N=13-14) atoms in both rigid /(non rigid) clusters.The geometry of the cluster is obtained by an embedded-atom (EA) mode potential, and the interaction between the molecule and cIuster is described by a LEPS -London-Eyring -Polanyi-Sato) potential energy function.Both channels the reactive dissociative adsorption of the molecule on the cIuster) and non reactive (scattering of the molecule from the cluster) are considered. The dissociative chemisorption probability, cross section and rate constant are studied as functions of the initial quantal rovibrational state of the molecule, collision energy, impact parameter and the temperature (OK,296K,834K ,1014K,1554K) of the clusters

Understanding Catalytic Activity Trends for NO Decomposition and CO Oxidation using Density Functional Theory and Microkinetic Modeling

DEFF Research Database (Denmark)

Falsig, Hanne

-metal surfaces by combining a database of adsorption energies on stepped metal surfaces with known Brønsted–Evans–Polanyi (BEP) relations for the activation barriers of dissociation of diatomic molecules over stepped transition- and noble-metal surfaces. The potential energy diagram directly points to why Pd......The main aim of this thesis is to understand the catalytic activity of transition metals and noble metals for the direct decomposition of NO and the oxidation of CO. The formation of NOx from combustion of fossil and renewable fuels continues to be a dominant environmental issue. We take one step...... towards rationalizing trends in catalytic activity of transition metal catalysts for NO decomposition by combining microkinetic modelling with density functional theory calculations. We establish the full potential energy diagram for the direct NO decomposition reaction over stepped transition...

The adsorption of argon, krypton and xenon on activated charcoal

International Nuclear Information System (INIS)

Underhill, D.W.

1996-01-01

Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs

Adsorption of microcystin-LR on mesoporous carbons and its potential use in drinking water source.

Science.gov (United States)

Park, Jeong-Ann; Jung, Sung-Mok; Yi, In-Geol; Choi, Jae-Woo; Kim, Song-Bae; Lee, Sang-Hyup

2017-06-01

Microcystin-LR (MC-LR) is a common toxin derived from cyanobacterial blooms an effective, rapid and non-toxic method needs to be developed for its removal from drinking water treatment plants (DWTP). For an adsorption-based method, mesoporous carbon can be a promising supplemental adsorbent. The effect of mesoporous carbon (MC1, MC2, and MC3) properties and water quality parameters on the adsorption of MC-LR were investigated and the results were analyzed by kinetic, isotherm, thermodynamic, Derjaguin-Landau-Verwey-Overbeek (DLVO), and intraparticle diffusion models. MC1 was the most appropriate type for the removal of MC-LR with a maximum adsorption capacity of 35,670.49 μg/g. Adsorption of MC-LR is a spontaneous reaction dominated by van der Waals interactions. Pore sizes of 8.5-14 nm enhance the pore diffusion of MC-LR from the surface to the mesopores of MC1. The adsorption capacity was not sensitive to changes in the pH (3.2-8.0) and the existence of organic matter (2-5 mg/L). Furthermore, the final concentration of MC-LR was below the WHO guideline level after a 10-min reaction with 20 mg/L of MC1 in the Nak-Dong River, a drinking water source. The MC-LR adsorption mainly competed with humic substances (500-1000 g/mole); however, they did not have a great effect on adsorption. Copyright © 2017. Published by Elsevier Ltd.

Adsorption behavior of protein onto siloxane microspheres

International Nuclear Information System (INIS)

Liu Bailing; Cao Shunsheng; Deng Xiaobo; Li Songjun; Luo Rong

2006-01-01

The siloxane microspheres with core-shell structure (PMMA/PMPS) (MMA, methyl methacrylate; MPS, 3-methacryloxypropyl-trimethoxysilane) have been prepared by dispersion polymerization as described in our previous work. In this paper, the developed poly(MMA-MPS) microspheres, as a carrier, are used to investigate the adsorption behavior of bovine serum albumin (BSA) on them. The Langmuir and Freundlich models have been applied to describe the adsorption behavior. The experimental results indicated that the presence of PMPS evidently increases the adsorption rate and the amount of protein, and it also influences the interaction of BSA molecules. The adsorption of BSA on the poly(MMA-MPS) microspheres seems to be sensitive to pH and ionic strength. The fittings curves from Langmuir and Freundlich models showed that the adsorption was actually more complicated than ideal situation because one or more interactions were involved in the process. For understanding the electronic contribution, the Zeta potential was used to measure the reactive system before and after protein adsorption

Adsorption behavior of protein onto siloxane microspheres

Energy Technology Data Exchange (ETDEWEB)

Liu Bailing [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China)]. E-mail: Blliuchem@hotmail.com; Cao Shunsheng [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Deng Xiaobo [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Li Songjun [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China); Luo Rong [Chengdu Institute of Organic Chemistry, Graduate School of CAS, Chinese Academy of Sciences, Chengdu 610041 (China)

2006-09-15

The siloxane microspheres with core-shell structure (PMMA/PMPS) (MMA, methyl methacrylate; MPS, 3-methacryloxypropyl-trimethoxysilane) have been prepared by dispersion polymerization as described in our previous work. In this paper, the developed poly(MMA-MPS) microspheres, as a carrier, are used to investigate the adsorption behavior of bovine serum albumin (BSA) on them. The Langmuir and Freundlich models have been applied to describe the adsorption behavior. The experimental results indicated that the presence of PMPS evidently increases the adsorption rate and the amount of protein, and it also influences the interaction of BSA molecules. The adsorption of BSA on the poly(MMA-MPS) microspheres seems to be sensitive to pH and ionic strength. The fittings curves from Langmuir and Freundlich models showed that the adsorption was actually more complicated than ideal situation because one or more interactions were involved in the process. For understanding the electronic contribution, the Zeta potential was used to measure the reactive system before and after protein adsorption.

Modeling adsorption of binary and ternary mixtures on microporous media

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2007-01-01

it possible using the same equation of state to describe the thermodynamic properties of the segregated and the bulk phases. For comparison, we also used the ideal adsorbed solution theory (IAST) to describe adsorption equilibria. The main advantage of these two models is their capabilities to predict......The goal of this work is to analyze the adsorption of binary and ternary mixtures on the basis of the multicomponent potential theory of adsorption (MPTA). In the MPTA, the adsorbate is considered as a segregated mixture in the external potential field emitted by the solid adsorbent. This makes...... multicomponent adsorption equilibria on the basis of single-component adsorption data. We compare the MPTA and IAST models to a large set of experimental data, obtaining reasonable good agreement with experimental data and high degree of predictability. Some limitations of both models are also discussed....

Competitive Protein Adsorption - Multilayer Adsorption and Surface Induced Protein Aggregation

DEFF Research Database (Denmark)

Holmberg, Maria; Hou, Xiaolin

2009-01-01

In this study, competitive adsorption of albumin and IgG (immunoglobulin G) from human serum solutions and protein mixtures onto polymer surfaces is studied by means of radioactive labeling. By using two different radiolabels (125I and 131I), albumin and IgG adsorption to polymer surfaces...... is monitored simultaneously and the influence from the presence of other human serum proteins on albumin and IgG adsorption, as well as their mutual influence during adsorption processes, is investigated. Exploring protein adsorption by combining analysis of competitive adsorption from complex solutions...... of high concentration with investigation of single protein adsorption and interdependent adsorption between two specific proteins enables us to map protein adsorption sequences during competitive protein adsorption. Our study shows that proteins can adsorb in a multilayer fashion onto the polymer surfaces...

Adsorption of ferrous ions onto montmorillonites

Science.gov (United States)

Qin, Dawei; Niu, Xia; Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao

2015-04-01

The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe2+/Fetotal ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG0 and ΔH0 were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

Carbon dioxide adsorption in graphene sheets

Directory of Open Access Journals (Sweden)

Ashish Kumar Mishra

2011-09-01

Full Text Available Control over the CO2 emission via automobiles and industrial exhaust in atmosphere, is one of the major concerns to render environmental friendly milieu. Adsorption can be considered to be one of the more promising methods, offering potential energy savings compared to absorbent systems. Different carbon nanostructures (activated carbon and carbon nanotubes have attracted attention as CO2 adsorbents due to their unique surface morphology. In the present work, we have demonstrated the CO2 adsorption capacity of graphene, prepared via hydrogen induced exfoliation of graphitic oxide at moderate temperatures. The CO2 adsorption study was performed using high pressure Sieverts apparatus and capacity was calculated by gas equation using van der Waals corrections. Physical adsorption of CO2 molecules in graphene was confirmed by FTIR study. Synthesis of graphene sheets via hydrogen exfoliation is possible at large scale and lower cost and higher adsorption capacity of as prepared graphene compared to other carbon nanostructures suggests its possible use as CO2 adsorbent for industrial application. Maximum adsorption capacity of 21.6 mmole/g was observed at 11 bar pressure and room temperature (25 ºC.

Evidence for a pore-filling mechanism in the adsorption of aromatic hydrocarbons to a natural wood char.

Science.gov (United States)

Nguyen, Thanh H; Cho, Hyun-Hee; Poster, Dianne L; Ball, William P

2007-02-15

Sorption isotherms for five aromatic hydrocarbons were obtained with a natural wood char (NC1) and its residue after solvent extraction (ENC1). Substantial isotherm nonlinearity was observed in all cases. ENC1 showed higher BET surface area, higher nitrogen-accessible micropore volume, and lower mass of extractable organic chemicals, including quantifiable polycyclic aromatic hydrocarbons (PAHs),while the two chars showed identical surface oxygen/ carbon (O/C) ratio. For two chlorinated benzenes that normally condense as liquids at the temperatures used, sorption isotherms with NC1 and ENC1 were found to be statistically identical. For the solid-phase compounds (1,4-dichlorobenzene (1,4-DCB) and two PAHs), sorption was statistically higher with ENC1, thus demonstrating sorption effects due to both (1) authigenic organic content in the sorbentand (2)the sorbate's condensed state. Polanyi-based isotherm modeling, pore size measurements, and comparisons with activated carbon showthe relative importance of adsorptive pore filling and help explain results. With both chars, maximum sorption increased in the order of decreasing molecular diameter: phenanthrene < naphthalene < 1,2-dichlorobenzene/1,2,4-trichlorobenzene < 1,4-DCB. Comparison of 1,4- and 1,2-DCB shows that the critical molecular diameter was apparently more important than the condensed state, suggesting that 1,4-DCB sorbed in the liquid state for ENC1.

ADSORPTION RATE CONSTANTS OF EOSIN IN HUMIN

OpenAIRE

anshar, andi muhammad

2015-01-01

Eosin is one of the dyes commonly used in the industry and has the potential to cause pollution of the water environment. The Eosin pollution treatment methods used in this study was the adsorption method using humin fraction obtained from the peat land comes from Kalimantan. From the research data showed that the adsorption of eosin in humin result of washing with HCl / HF optimum at pH 4 and a contact time of 60 minutes with the adsorption-order rate was 8,4 x 10-3 min-1

Adsorption of ferrous ions onto montmorillonites

Energy Technology Data Exchange (ETDEWEB)

Qin, Dawei, E-mail: qdw109@163.com [Qilu University of Technology, Jinan, 250353, Shandong (China); Niu, Xia [Qilu University of Technology, Jinan, 250353, Shandong (China); Qiao, Min; Liu, Gang; Li, Hongxin; Meng, Zhenxiao [Shandong SiBang pharmaceutical co., LTD, Jinan, Shandong, 250200 (China)

2015-04-01

Highlights: • Adsorption study of ferrous ions on montmorillonites. • Using ascorbic acid as antioxidants in adsorption process. • Fe (II)-MMT had good affinity for phosphate. - Abstract: The adsorption of Fe (II) onto montmorillonites was investigated through initial concentration, contact time, pH and temperature. During the whole adsorption process, the ascorbic acid (Vitamin C) was added as a kind of antioxidant, at the same time, deionized water (after boiling) and nitrogen protection were also used to avoid oxidation. The Fe{sup 2+}/Fe{sub total} ratio of the iron exists in the Fe-montmorillonites was found more than 95%. Two kinetic models, including pseudo-first-order and pseudo-second-order model, were used to analyze the adsorption process of Fe (II) on montmorillonites. The results of our study showed that adsorption process fitted with pseudo-second-order well. Adsorption isotherms showed that Langmuir model was better than Freundlich model. The thermodynamic parameters ΔG{sup 0} and ΔH{sup 0} were 3.696 kJ/mol and 6.689 kJ/mol (we just gave the values at 298 K), respectively. The positive values at different temperatures showed that the adsorption process was non-spontaneous and endothermic. The characteristics of materials were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Surface area and porosity analyzer, Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC) and Zeta potential distribution.

Interfacial adsorption of insulin - Conformational changes and reversibility of adsorption

NARCIS (Netherlands)

Mollmann, SH; Jorgensen, L; Bukrinsky, JT; Elofsson, U; Norde, W; Frokjaer, S

The adsorption of human insulin to Teflon particles was studied with respect to conformational changes and the reversibility of adsorption was examined by total internal reflection fluorescence (TIRF). Adsorption isotherms for the adsorption of human insulin indicated high affinity adsorption, even

Adsorption of Ca2+ on single layer graphene oxide.

Science.gov (United States)

Terracciano, Amalia; Zhang, Jianfeng; Christodoulatos, Christos; Wu, Fengchang; Meng, Xiaoguang

2017-07-01

Graphene oxide (GO) holds great promise for a broad array of applications in many fields, but also poses serious potential risks to human health and the environment. In this study, the adsorptive properties of GO toward Ca 2+ and Na + were investigated using batch adsorption experiments, zeta potential measurements, and spectroscopic analysis. When pH increased from 4 to 9, Ca 2+ adsorption by GO and the zeta potential of GO increased significantly. Raman spectra suggest that Ca 2+ was strongly adsorbed on the GO via -COOCa + formation. On the other hand, Na + was adsorbed into the electrical diffuse layer as an inert counterion to increase the diffuse layer zeta potential. While the GO suspension became unstable with increasing pH from 4 to 10 in the presence of Ca 2+ , it was more stable at higher pH in the NaCl solution. The findings of this research provide insights in the adsorption of Ca 2+ on GO and fundamental basis for prediction of its effect on the colloidal stability of GO in the environment. Copyright © 2017. Published by Elsevier B.V.

Adsorption of lithium-lanthanum films on W (112) face

International Nuclear Information System (INIS)

Gupalo, M.S.; Smereka, T.P.; Palyukh, B.M.; Babkin, G.V.

1986-01-01

The method of contact potential difference is employed to study the electron adsorption properties (the work function phi and adsorption heat q) lithium films on a lanthanized W(112) surface. It is found that the work function of mixed lithium-lanthanum films is intermediate between phi of the summands. The presence of lanthanum on a W(112) face reduces the adsorption heat of lithium

Application of activated carbon derived from scrap tires for adsorption of Rhodamine B.

Science.gov (United States)

Li, Li; Liu, Shuangxi; Zhu, Tan

2010-01-01

Activated carbon derived from solid hazardous waste scrap tires was evaluated as a potential adsorbent for cationic dye removal. The adsorption process with respect to operating parameters was investigated to evaluate the adsorption characteristics of the activated pyrolytic tire char (APTC) for Rhodamine B (RhB). Systematic research including equilibrium, kinetics and thermodynamic studies was performed. The results showed that APTC was a potential adsorbent for RhB with a higher adsorption capacity than most adsorbents. Solution pH and temperature exert significant influence while ionic strength showed little effect on the adsorption process. The adsorption equilibrium data obey Langmuir isotherm and the kinetic data were well described by the pseudo second-order kinetic model. The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption process. Thermodynamic study confirmed that the adsorption was a physisorption process with spontaneous, endothermic and random characteristics.

Kinetic and equilibrium study of uranium(VI) adsorption by Bacillus licheniformis

International Nuclear Information System (INIS)

Zheng-ji Yi; University of Science and Technology Beijing, Beijing; Jun Yao

2012-01-01

Uranium pollution is a severe problem worldwide. Biosorption has been proposed as one of the most promising technologies for the removal of uranyl cations. Here we report on the adsorption behavior of uranium(VI) [U(VI)] on Bacillus licheniformis biomass to explore the potentiality of its application in uranium contamination control. The adsorption equilibrium, adsorption kinetics, and effects of temperature, pH and initial biosorbent dosage on the adsorption equilibrium were investigated in detail through batch experiments. The adsorption process is pronouncedly affected by the solution pH and the optimum pH range should be 4.5-5.0.Temperature range from 25 to 45 deg C has a certain effect on the rate of biosorption, but little effect on the equilibrium adsorption capacity. The U(VI) percentage removal increased concurrently with increasing biomass dosage, whereas the adsorption capacity decreased. The process follows the Langmuir isotherm model. The adsorption kinetics data were fitted very well by the pseudo-first-order rate model. Finally, the calculation results of thermodynamic constant (ΔG a = 9.98 kJ/mol) reveal that the adsorption process can be identified as a spontaneous chemical process. The present results suggest that B. licheniformis has considerable potential for the removal of uranyl from aqueous solution. (author)

La place de l’économie de marché dans une société rurale malgache : l’actualité des travaux de Polanyi

Directory of Open Access Journals (Sweden)

Antoine Deliège

2008-12-01

Full Text Available La pertinence des outils forgés par Karl Polanyi est manifeste pour comprendre la place de l’économie dans les sociétés dites « en voie de développement ». A travers l’étude d’une société rurale de Madagascar, l’auteur montre qu’il est difficile voire impossible de saisir les formes d’échanges en dehors de leur substrat social. Même si l’économie capitaliste s’est infiltrée en son sein, elle ne constitue pas une sphère propre. Au contraire, les comportements économiques sont enfouis, parfois dissimulés, mais toujours « encastrés » dans l’épaisseur insécable du social. L’analyse d’une cérémonie post-mortuaire- famadihana- illustre parfaitement l’interdépendance entre les logiques culturelle, symbolique, sociale et économique dans la société rurale merina. Cet exemple montre que si le marché est indispensable à la société rurale malgache pour sortir de la pauvreté, d’autres régulations que la seule régulation marchande sont présentes, possibles, recherchées et nécessaires.Nowadays, the concepts created by Karl Polanyi are still very helpful to understand the place of economy in society and especially in the “developing” countries. In analyzing a rural society of Madagascar, this paper argues that it is difficult, even impossible, to analyze the forms of exchange without their cultural substance. Even tough the capitalist economy is present; it does not constitute a separate sphere. On the contrary, the economic behaviors are buried, sometimes dissimulated, but always embedded in the social. The study of a post-mortem ceremony- famadihana- will illustrate the interdependence among the cultural, symbolic, social and economic logics in a merina rural society. This example will show that if the market is indispensable to the Malagasy rural society to avoid poverty, others regulations than the unique market regulation are present, possible, desirable and necessary.

Competitive adsorption of a two-component gas on a deformable adsorbent

International Nuclear Information System (INIS)

Usenko, A S

2014-01-01

We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas is obtained, taking into account variations in the adsorption properties of the adsorbent in adsorption. We establish bistability and tristability of the system caused by variations in adsorption properties of the adsorbent in competitive adsorption of gas particles on it. We derive conditions under which adsorption isotherms of a binary gas mixture have two stable asymptotes. It is shown that the specific features of the behavior of the system under study can be described in terms of a potential of the known explicit form. (paper)

Theoretical study of adsorption of lithium atom on carbon nanotube

OpenAIRE

Senami, Masato; Ikeda, Yuji; Fukushima, Akinori; Tachibana, Akitomo

2011-01-01

We investigate the adsorption of lithium atoms on the surface of the (12, 0) single wall carbon nanotube (SWCNT) by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsiv...

Phosphate-mediated electrochemical adsorption of cisplatin on gold electrodes

International Nuclear Information System (INIS)

Kolodziej, Adam; Figueiredo, Marta C.; Koper, Marc T.M.; Fernandez-Trillo, Francisco; Rodriguez, Paramaconi

2017-01-01

Highlights: •The potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode is mediated by the adsorption of phosphate anions on gold electrode. •Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. •Upon reduction of the phosphate-mediated cisplatin adsorption, the platinum deposits are formed by 3D nanoclusters -- Abstract: This manuscript reports the potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode. It was found that this process is mediated by the adsorption of phosphate anions on the gold electrode and that the maximum coverage of Pt adsorbed is given by the maximum coverage of phosphate adsorbed at a given potential. The interaction of cisplatin with the phosphate groups was confirmed by in situ FTIR spectroscopy under external reflexion configuration. Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. Moreover, the relationship between the charge of the Pt deposited and the charge of the electrochemical surface area of the Pt deposited on the gold electrodes indicates that 3D nanoclusters of a few atoms of Pt were formed over the gold electrode upon the electrochemical reduction of the adsorbed cisplatin. The Pt nanoclusters formed under these conditions were later evaluated for the oxidation of a monolayer of carbon monoxide. The Pt nanoclusters showed a high overpotential for the oxidation of the carbon monoxide monolayer and the high oxidation overpotential was attributed to the absence of adsorption sites for OH species on the Pt clusters: only at potentials where the OH species are adsorbed at the edge between the Pt nanocluster and the gold support, the oxidation of the carbon monoxide on the Pt nanoparticles takes place.

Adsorption of arsenate from aqueous solution by rice husk-based adsorbent

International Nuclear Information System (INIS)

Khan, Taimur; Chaudhuri, Malay

2013-01-01

Rice husk-based adsorbent (RHBA) was prepared by burning rice husk in a muffle furnace at 400°C for 4 h and adsorption of arsenate by the RHBA from aqueous solution was examined. Batch adsorption test showed that extent of arsenate adsorption depended on contact time and pH. Equilibrium adsorption was attained in 60 min, with maximum adsorption occurring at pH 7. Equilibrium adsorption data were well described by the Freundlich isotherm model. Freundlich constants K f and 1/n were 3.62 and 2, respectively. The RHBA is effective in the adsorption of arsenate from water and is a potentially suitable filter medium for removing arsenate from groundwater at wells or in households.

Evaluation of the potential of red mud heat treated at 400 deg C in adsorption of textile dyes

International Nuclear Information System (INIS)

Antunes, M.L.P.; Rangueri, T.B.

2011-01-01

The production of aluminum metal generates a huge amount of red mud as industrial waste. The storage of such material causes serious environmental damage and needs large area for your disposal. Develop technologies that allow its reuse is an alternative. Studies show that the mud has adsorbent properties and may be used in the treatment of wastewater, gas and textiles. This work presents the characterization by X-ray diffraction and surface area of the red mud Brazilian thermally activated at 400 deg C to evaluate the adsorption capacity of this material to the dye reactive blue 19 in pH 4. Through the construction of the Langmuir isotherm was determined adsorption capacity, which, in alkaline media, got an average of 136.9 mg / g. The results suggest that under certain conditions, the red mud has potential as an alternative adsorbent and low cost. (author)

Adsorptive properties of alluvial soil for arsenic(V) and its potential for protection of the shallow groundwater among Changsha, Zhuzhou, and Xiangtan cities, China.

Science.gov (United States)

Chen, Hongwei; Mei, Jinhua; Luo, Yueping; Qiu, Anni; Wang, Huan

2017-02-01

The study area is among Changsha, Zhuzhou, and Xiangtan cities, which was under agricultural use and natural conditions about 10 years ago and now is becoming part of the metropolis because of the urban expansion. This study aims to investigate the mechanisms and capabilities of the local alluvial soil layer for protecting the local shallow groundwater from arsenic pollution by field surveys and batch experiments. The field surveys showed that there was an acidic tendency of the groundwater, and phosphate, nitrate, and arsenic in the groundwater significantly increased comparing to their reference values. It indicates that the disturbance of the former agricultural land due to the change of land use may be responsible for these changes. From the experimental results, the maximum adsorption capacity of the soil for As(V) was as low as 0.334 mg/g, and lower As(V) adsorption capacities were obtained at higher As(V) concentration, higher pH, and lower temperature. The presence of H 2 PO 4 - and SiO 3 2- posed negative, while HCO 3 - slight positive, and SO 4 2- , NO 3 - and Cl - negligible influences on the As(V) adsorption. The surface-derived organic matter played a negative role in the adsorption process, and low specific surface area influenced adsorption capacity of the soil. The study reveals that the local soil layer shows poor potential for protection of the local shallow groundwater from As(V) pollution, and the change trends of the groundwater environments due to more intensive anthropogenic activities will further weaken this potential and increase the risk of the groundwater contamination.

Adsorption of organic stormwater pollutants onto activated carbon from sewage sludge.

Science.gov (United States)

Björklund, Karin; Li, Loretta Y

2017-07-15

Adsorption filters have the potential to retain suspended pollutants physically, as well as attracting and chemically attaching dissolved compounds onto the adsorbent. This study investigated the adsorption of eight hydrophobic organic compounds (HOCs) frequently detected in stormwater - including four polycyclic aromatic hydrocarbons (PAHs), two phthalates and two alkylphenols - onto activated carbon produced from domestic sewage sludge. Adsorption was studied using batch tests. Kinetic studies indicated that bulk adsorption of HOCs occurred within 10 min. Sludge-based activated carbon (SBAC) was as efficient as tested commercial carbons for adsorbing HOCs; adsorption capacities ranged from 70 to 2800 μg/g (C initial  = 10-300 μg/L; 15 mg SBAC in 150 mL solution; 24 h contact time) for each HOC. In the batch tests, the adsorption capacity was generally negatively correlated to the compounds' hydrophobicity (log K ow ) and positively associated with decreasing molecule size, suggesting that molecular sieving limited adsorption. However, in repeated adsorption tests, where competition between HOCs was more likely to occur, adsorbed pollutant loads exhibited strong positive correlation with log K ow . Sewage sludge as a carbon source for activated carbon has great potential as a sustainable alternative for sludge waste management practices and production of a high-capacity adsorption material. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of adsorption performance deterioration in silica gel–water adsorption refrigeration

International Nuclear Information System (INIS)

Wang Dechang; Zhang Jipeng; Xia Yanzhi; Han Yanpei; Wang Shuwei

2012-01-01

Highlights: ► Adsorption deterioration of silica gel in refrigeration systems is verified. ► Possible factors to cause such deterioration are analyzed. ► Specific surface area, silanol content and adsorption capacity are tested. ► The pollution is the primary factor to decline the adsorption capacity. ► Deteriorated samples are partly restored after being processed by acid solution. - Abstract: Silica gel acts as a key role in adsorption refrigeration systems. The adsorption deterioration must greatly impact the performance of the silica gel–water adsorption refrigeration system. In order to investigate the adsorption deterioration of silica gel, many different silica gel samples were prepared according to the application surroundings of silica gel in adsorption refrigeration systems after the likely factors to cause such deterioration were analyzed. The specific surface area, silanol content, adsorption capacity and pore size distribution of those samples were tested and the corresponding adsorption isotherms were achieved. In terms of the experimental data comparisons, it could be found that there are many factors to affect the adsorption performance of silica gel, but the pollution was the primary one to decline the adsorption capacity. In addition, the adsorption performance of the deteriorated samples after being processed by acid solution was explored in order to find the possible methods to restore its adsorption performance.

Adsorption of polycyclic aromatic hydrocarbons by graphene and graphene oxide nanosheets.

Science.gov (United States)

Wang, Jun; Chen, Zaiming; Chen, Baoliang

2014-05-06

The adsorption of naphthalene, phenanthrene, and pyrene onto graphene (GNS) and graphene oxide (GO) nanosheets was investigated to probe the potential adsorptive sites and molecular mechanisms. The microstructure and morphology of GNS and GO were characterized by elemental analysis, XPS, FTIR, Raman, SEM, and TEM. Graphene displayed high affinity to the polycyclic aromatic hydrocarbons (PAHs), whereas GO adsorption was significantly reduced after oxygen-containing groups were attached to GNS surfaces. An unexpected peak was found in the curve of adsorption coefficients (Kd) with the PAH equilibrium concentrations. The hydrophobic properties and molecular sizes of the PAHs affected the adsorption of G and GO. The high affinities of the PAHs to GNS are dominated by π-π interactions to the flat surface and the sieving effect of the powerful groove regions formed by wrinkles on GNS surfaces. In contrast, the adsorptive sites of GO changed to the carboxyl groups attaching to the edges of GO because the groove regions disappeared and the polar nanosheet surfaces limited the π-π interactions. The TEM and SEM images initially revealed that after loading with PAH, the conformation and aggregation of GNS and GO nanosheets dramatically changed, which explained the observations that the potential adsorption sites of GNS and GO were unusually altered during the adsorption process.

Adsorption of dodecylamine hydrochloride on graphene oxide in water

Directory of Open Access Journals (Sweden)

Peng Chen

Full Text Available Cationic surfactants in water are difficult to be degraded, leading to serious water pollution. In this work, graphene oxide (GO was used as an adsorbent for removing Dodecylamine Hydrochloride (DACl, a representative cationic surfactant. X-ray diffraction (XRD, FT-IR spectroscopy and atomic force microscope (AFM were used to characterize the prepared GO. The adsorption of DACl on GO have been investigated through measurements of adsorption capacity, zeta potential, FTIR, and X-ray photoelectron spectroscopy (XPS. The experimental results have shown that the adsorption kinetics could be described as a rate-limiting pseudo second-order process, and the adsorption isotherm agreed well with the Freundlich model. GO was a good adsorbent for DACl removal, compared with coal fly ash and powdered activated carbon. The adsorption process was endothermic, and could be attributed to electrostatic interaction and hydrogen bonding between DACl and GO. Keywords: Graphene oxide, Dodecylamine hydrochloride, Adsorption isotherm, Adsorption mechanisms

Electrostatically mediated adsorption by nanodiamond and nanocarbon particles

International Nuclear Information System (INIS)

Gibson, Natalie M.; Luo, Tzy-Jiun Mark; Shenderova, Olga; Koscheev, Alexey P.; Brenner, Donald W.

2012-01-01

Nanodiamond (ND) and other nanocarbon particles are popular platforms for the immobilization of molecular species. In the present research, factors affecting adsorption and desorption of propidium iodide (PI) dye, chosen as a charged molecule model, on ND and sp 2 carbon nanoparticles were studied, with a size ranging from 75 to 4,305 nm. It was found that adsorption of PI molecules, as characterized by ultraviolet–visible spectroscopy, on ND particles is strongly influenced by sorbent-sorbate electrostatic interactions. Different types of NDs with a negative zeta potential were found to adsorb positively charged PI molecules, while no PI adsorption was observed for NDs with a positive zeta potential. The type and density of surface groups of negatively charged NDs greatly influenced the degree and capacity of the PI adsorbed. Ozone-purified NDs had the highest capacity for PI adsorption, due to its greater density of oxygen containing groups, i.e., acid anhydrides and carboxyls, as assessed by TDMS and TOF–SIMS. Single wall nanohorns and carbon onion particles were found to adsorb PI regardless of their zeta potential; this is likely due to π bonding between the aromatic rings of PI and the graphitic surface of the materials and the internal cavity of the horns.

Electrostatically mediated adsorption by nanodiamond and nanocarbon particles

Energy Technology Data Exchange (ETDEWEB)

Gibson, Natalie M.; Luo, Tzy-Jiun Mark, E-mail: tluo@ncsu.edu; Shenderova, Olga [North Carolina State University, Department of Materials Science and Engineering (United States); Koscheev, Alexey P. [Karpov Institute of Physical Chemistry, State Scientific Center of Russian Federation (Russian Federation); Brenner, Donald W. [North Carolina State University, Department of Materials Science and Engineering (United States)

2012-03-15

Nanodiamond (ND) and other nanocarbon particles are popular platforms for the immobilization of molecular species. In the present research, factors affecting adsorption and desorption of propidium iodide (PI) dye, chosen as a charged molecule model, on ND and sp{sup 2} carbon nanoparticles were studied, with a size ranging from 75 to 4,305 nm. It was found that adsorption of PI molecules, as characterized by ultraviolet-visible spectroscopy, on ND particles is strongly influenced by sorbent-sorbate electrostatic interactions. Different types of NDs with a negative zeta potential were found to adsorb positively charged PI molecules, while no PI adsorption was observed for NDs with a positive zeta potential. The type and density of surface groups of negatively charged NDs greatly influenced the degree and capacity of the PI adsorbed. Ozone-purified NDs had the highest capacity for PI adsorption, due to its greater density of oxygen containing groups, i.e., acid anhydrides and carboxyls, as assessed by TDMS and TOF-SIMS. Single wall nanohorns and carbon onion particles were found to adsorb PI regardless of their zeta potential; this is likely due to {pi} bonding between the aromatic rings of PI and the graphitic surface of the materials and the internal cavity of the horns.

SQUARE WAVE CATHODIC STRIPPING VOLTAMMETRY ADSORPTIVE FOR NICKEL AND COBALT ANALYSIS

Directory of Open Access Journals (Sweden)

Saryati Saryati

2010-06-01

Full Text Available The adsorptive stripping voltammetric determination of Ni and Co based on adsorption of the Ni/Co and dimethylglioxime (DMG complex on a hanging mercury drop electrode is studied. The reduction current of the adsorbed DMG complex is measured by square wave cathodic stripping voltammetry method. The effect of various parameters such as ligand concentration, pH of supporting electrolytic, adsorption potential and adsorption time on the current peak of Ni and Co voltammogram were studied. Optimum condition of this method are supporting electrolyte pH 9, DMG concentration 5×10 -4 M, adsorption potential -0.7 V vs Ag/AgCl and adsorption time 180 second. A linier relationship between the current peak and Ni or Co concentration was obtained in the range 5 - 30 ng/mL and the detection limit 0.6 ng/ml for both Ni and Co. The recovery of Ni and Co were 98.11-104.17% using standard biological materials with RSD 2.59 - 10.37%. Based on ";t"; test can be conclude that the result are nearly equal to the standard reference material.   Keywords: adsorptive stripping voltammetric, dimethylglioxime complex, nickel, cobalt

Fluorocarbon adsorption in hierarchical porous frameworks

Energy Technology Data Exchange (ETDEWEB)

Motkuri, RK; Annapureddy, HVR; Vijaykumar, M; Schaef, HT; Martin, PF; McGrail, BP; Dang, LX; Krishna, R; Thallapally, PK

2014-07-09

Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g(-1) at a very low relative saturation pressure (P/P-o) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g(-1) at P/P-o of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

Topotactic growth, selective adsorption, and adsorption-driven photocatalysis of protonated layered titanate nanosheets.

Science.gov (United States)

Wu, Qili; Yang, Xianfeng; Liu, Jia; Nie, Xin; Huang, Yongliang; Wen, Yuping; Khan, Javid; Khan, Wasim U; Wu, Mingmei; An, Taicheng

2014-10-22

Layered titanates with selective adsorption ability and adsorption-driven photocatalytic property can be quite attractive due to their potential applications in water purification. In this work, lepidocrocite-like layered protonated titanate (H2Ti2O5·H2O, denoted as HTO) nanosheets were successfully synthesized by an ion-exchange process. It turns out that this layered structure displays an abundant and selective adsorption toward the fluoroquinolone pharmaceutical compared with some large dye molecules due to a size selectivity of the interlayer spacing of HTO and the molecular horizontal size, as well as their electrostatic interaction. The uptake ability of HTO could be readily controlled through adjusting the pH values of adsorbate solution, and the maximum uptake capacity was achieved at the pH value of about 5.5 for ciprofloxacin (CIP) and 6.5 for moxifloxacin (MOX). The adsorption amount of smaller nalidixic acid (NAL) showed an increasing tendency as the pH value decreased. Moreover, the two-dimensional layered crystal structure also permits such HTO nanosheets to have a large percentage of (010) faces exposed, which is considerably provided by the interlayer surfaces of these nanosheets. The (010) surface has a similar Ti and O atomic arrangement as to the highly reactive anatase TiO2(001) one. Due to these specific characteristics, these HTO nanosheets show excellent photocatalytic activity in degrading CIP under UV light irradiation as well as possess a superior adsorption ability to remove CIP from aqueous solution selectively and efficiently. The photocatalytic reaction is believed to be mainly conducted on the active anatase (001)-like interlayer (010) surfaces of the layered structures since the as-prepared HTO performs an adsorption-driven molecular recognitive photocatalytic reaction.

Acetate and phosphate anion adsorption linear sweep voltammograms simulated using density functional theory

KAUST Repository

Savizi, Iman Shahidi Pour

2011-04-01

Specific adsorption of anions to electrode surfaces may alter the rates of electrocatalytic reactions. Density functional theory (DFT) methods are used to predict the adsorption free energy of acetate and phosphate anions as a function of Pt(1 1 1) electrode potential. Four models of the electrode potential are used including a simple vacuum slab model, an applied electric field model with and without the inclusion of a solvating water bi-layer, and the double reference model. The linear sweep voltammogram (LSV) due to anion adsorption is simulated using the DFT results. The inclusion of solvation at the electrochemical interface is necessary for accurately predicting the adsorption peak position. The Langmuir model is sufficient for predicting the adsorption peak shape, indicating coverage effects are minor in altering the LSV for acetate and phosphate adsorption. Anion adsorption peak positions are determined for solution phase anion concentrations present in microbial fuel cells and microbial electrolysis cells and discussion is provided as to the impact of anion adsorption on oxygen reduction and hydrogen evolution reaction rates in these devices. © 2011 Elsevier Ltd. All rights reserved.

Adsorption of uranium on adsorbents produced from used tires

International Nuclear Information System (INIS)

Mahramanlioglu, M.

2003-01-01

Potential use of adsorbents produced from used tires for the removal of uranium from aqueous solutions is investigated. Two different adsorbents were used including char and activated carbon produced from used tires. The surface area was larger on activated carbon. Adsorption experiments were carried out as a function of time, adsorbent concentration, pH and initial concentration of uranium. The adsorption kinetics was found to follow the Lagergren equation. The rate constants of intraparticle diffusion and mass transfer coefficients were calculated. It was shown that the equilibrium data could be fitted by the Langmuir and Freundlich equations. The adsorption of uranium in the presence of different cations were also studied and the results were correlated with the ionic potential of the cations. It was demonstrated that the activated carbon produced from used tires can be considered as an adsorbent that has a commercial potential for uranium removal. (author)

The components of the adsorption potential drop at the Ga and In-Ga electrodes in three solvents: a calculation with allowance for hydrophily of the Ag(111) single crystal face

International Nuclear Information System (INIS)

Emets, V.V.; Damaskin, B.B.; Kazarinov, V.E.

1996-01-01

The components of adsorption potential drop on the Ga and In-Ga electrodes in water, DMPA and DSMO, taking into account hydrophily of Ag(111) single crystal face in the framework of the metal-solvent contact modified model, have been recalculated. The data obtained are compared with the previously acquired ones. It is pointed out that corrections for the components of adsorptional potential relating to account of Ag(111) face hydrophily are not negligible. 8 refs., 1 tab

Numerical simulation and performance investigation of an advanced adsorption desalination cycle

KAUST Repository

Thu, Kyaw; Chakraborty, Anutosh; Kim, Youngdeuk; Myat, Aung; Saha, Bidyut Baran; Ng, Kim Choon

2013-01-01

Low temperature waste heat-driven adsorption desalination (AD) cycles offer high potential as one of the most economically viable and environmental-friendly desalination methods. This article presents the development of an advanced adsorption

Adsorption Property and Mechanism of Oxytetracycline onto Willow Residues

Directory of Open Access Journals (Sweden)

Di Wang

2017-12-01

Full Text Available To elucidate the adsorption property and the mechanism of plant residues to reduce oxytetracycline (OTC, the adsorption of OTC onto raw willow roots (WR-R, stems (WS-R, leaves (WL-R, and adsorption onto desugared willow roots (WR-D, stems (WS-D, and leaves (WL-D were investigated. The structural characterization was analyzed by scanning electron microscopy, Fourier-transform infrared spectra, and an elemental analyzer. OTC adsorption onto the different tissues of willow residues was compared and correlated with their structures. The adsorption kinetics of OTC onto willow residues was found to follow the pseudo-first-order model. The isothermal adsorption process of OTC onto the different tissues of willow residues followed the Langmuir and Freundlich model and the process was also a spontaneous endothermic reaction, which was mainly physical adsorption. After the willow residues were desugared, the polarity decreased and the aromaticity increased, which explained why the adsorption amounts of the desugared willow residues were higher than those of the unmodified residues. These observations suggest that the raw and modified willow residues have great potential as adsorbents to remove organic pollutants.

Identification of potential cell wall component that allows Taka-amylase A adsorption in submerged cultures of Aspergillus oryzae.

Science.gov (United States)

Sato, Hiroki; Toyoshima, Yoshiyuki; Shintani, Takahiro; Gomi, Katsuya

2011-12-01

We observed that α-amylase (Taka-amylase A; TAA) activity in the culture broth disappeared in the later stage of submerged cultivation of Aspergillus oryzae. This disappearance was caused by adsorption of TAA onto the cell wall of A. oryzae and not due to protein degradation by extracellular proteolytic enzymes. To determine the cell wall component(s) that allows TAA adsorption efficiently, the cell wall was fractionated by stepwise alkali treatment and enzymatic digestion. Consequently, alkali-insoluble cell wall fractions exhibited high levels of TAA adsorption. In addition, this adsorption capacity was significantly enhanced by treatment of the alkali-insoluble fraction with β-glucanase, which resulted in the concomitant increase in the amount of chitin in the resulting fraction. In contrast, the adsorption capacity was diminished by treating the cell wall fraction with chitinase. These results suggest that the major component that allows TAA adsorption is chitin. However, both the mycelium and the cell wall demonstrated the inability to allow TAA adsorption in the early stage of cultivation, despite chitin content in the cell wall being identical in both early and late stages of cultivation. These results suggest the existence of unidentified factor(s) that could prevent the adsorption of TAA onto the cell wall. Such factor(s) is most likely removed or diminished from the cell wall following longer cultivation periods.

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

International Nuclear Information System (INIS)

Cimino, R.; Neimark, A. V.; Rasmussen, C. J.

2013-01-01

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy

Communication: Thermodynamic analysis of critical conditions of polymer adsorption

Energy Technology Data Exchange (ETDEWEB)

Cimino, R.; Neimark, A. V., E-mail: aneimark@rutgers.edu [Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854 (United States); Rasmussen, C. J. [DuPont Central Research and Development, Corporate Center for Analytical Sciences, Macromolecular Characterization, Route 141 and Henry Clay, Wilmington, Delaware 19803 (United States)

2013-11-28

Polymer adsorption to solid surfaces is a ubiquitous phenomenon, which has attracted long-lasting attention. Dependent on the competition between the polymer-solid adsorption and polymer-solvent solvation interactions, a chain may assume either 3d solvated conformation when adsorption is weak or 2d adsorbed conformation when adsorption is strong. The transition between these conformations occurring upon variation of adsorption strength is quite sharp, and in the limit of “infinite” chain length, can be treated as a critical phenomenon. We suggest a novel thermodynamic definition of the critical conditions of polymer adsorption from the equality of incremental chemical potentials of adsorbed and free chains. We show with the example of freely jointed Lennard-Jones chains tethered to an adsorbing surface that this new definition provides a link between thermodynamic and geometrical features of adsorbed chains and is in line with classical scaling relationships for the fraction of adsorbed monomers, chain radii of gyration, and free energy.

Thermodynamic cycles of adsorption desalination system

International Nuclear Information System (INIS)

Wu, Jun W.; Hu, Eric J.; Biggs, Mark J.

2012-01-01

Highlights: ► Thermodynamic cycles of adsorption desalination (AD) system have been identified all possible evaporator temperature scenarios. ► Temperature of evaporator determines the cycle. ► Higher evaporator temperature leads to higher water production if no cooling is required. -- Abstract: The potential to use waste heat to co-generate cooling and fresh water from saline water using adsorption on silica is attracting increasing attention. A variety of different thermodynamic cycles of such an adsorption desalination (AD) system arise as the temperature of the saline water evaporator is varied relative to temperature of the water used to cool the adsorbent as it adsorbs the evaporated water. In this paper, all these possible thermodynamic cycles are enumerated and analysed to determine their relative performances in terms of specific energy consumption and fresh water productivity.

Direct measurements of adsorption heats of hydrogen on nano-porous carbons

International Nuclear Information System (INIS)

Akihiko Matsumoto; Kazumasa Yamamoto; Tomoyuki Miyata

2005-01-01

adsorption amounts at ca.10 MPa were 0.5 - 0.8 mass %, as exemplified in Figure 1 for A7, but the uptake per unit area for A7 is higher than that of A20, suggesting higher sorptivity on ACF of narrower pore size. In the case of adsorption in narrower micropores of A7, overlapping of the force fields of faced pore walls enhances the potential field in the micro-pore, and the enhancement is 1.75-fold. This potential enhancement would bring about higher sorptivity of hydrogen. Differential heats of adsorption on A7 were shown in Figure 2. The adsorption heats were 4 to 6 kJ/mol regardless of adsorption temperature, which agrees with calculated value based upon dispersion interaction (van der Waals interaction). Isosteric heats of adsorption were estimated from the adsorption isotherms by the Clausius-Clapeyron equation and they agreed well with the experimental results. These results suggest that hydrogen adsorption takes place even over critical temperature by dispersion interaction, and the pore width would play an important role in the sorptivity. (authors)

Electrochemical specific adsorption of halides on Cu 111, 100, and 211: A Density Functional Theory study

International Nuclear Information System (INIS)

McCrum, Ian T.; Akhade, Sneha A.; Janik, Michael J.

2015-01-01

The specific adsorption of ions onto electrode surfaces can affect electrocatalytic reactions. Density functional theory is used to investigate the specific adsorption of aqueous F − , Cl − , Br − , and I − onto Cu (111), (100), and (211) surfaces. The adsorption is increasingly favorable in the order of F − < Cl − < Br − < I − . The adsorption has a weak dependence on the surface facet, with adsorption most favorable on Cu (100) and least favorable on Cu (111). Potential ranges where specific adsorption would be expected on each facet are reported. The thermodynamics of bulk copper halide (CuX, CuX 2 ) formation are also investigated as a function of potential. CuX formation occurs at potentials slightly more positive of halide specific adsorption and of copper oxidation in aqueous electrolytes. Specifically adsorbed halides and bulk CuX may be present during a variety of electrochemical reactions carried out over a Cu electrode in halide containing electrolyte solutions

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance.

Science.gov (United States)

Elvira, Gutiérrez-Bonilla; Francisco, Granados-Correa; Víctor, Sánchez-Mendieta; Alberto, Morales-Luckie Raúl

2017-07-01

A series of MgO-based adsorbents were prepared through solution-combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N 2 physisorption measurements, and employed as potential adsorbents for CO 2 adsorption. The influence of structural and textural properties of these adsorbents over the CO 2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution-combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO 2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5hr (MgO-BM2.5h), exhibited the maximum CO 2 adsorption capacity of 1.611mmol/g at 25°C and 1atm, mainly via chemisorption. The CO 2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO 2 adsorption-desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution-combustion and treated by ball-milling during 2.5hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO 2 capture technologies. Copyright © 2016. Published by Elsevier B.V.

Theoretical study of adsorption of lithium atom on carbon nanotube

Directory of Open Access Journals (Sweden)

Masato Senami

2011-12-01

Full Text Available We investigate the adsorption of lithium atoms on the surface of the (12,0 single wall carbon nanotube (SWCNT by using ab initio quantum chemical calculations. The adsorption of one lithium atom on the inside of this SWCNT is favored compared to the outside. We check this feature by charge transfer and regional chemical potential density. The adsorption of multiple lithium atoms on the interior of the SWCNT is studied in terms of adsorption energy and charge transfer. We show that repulsive force between lithium atoms destabilizes a system for the large number of lithium atoms.

Potential adsorption of methylene blue from aqueous solution using green macroalgaePosidonia oceanica.

Science.gov (United States)

Allouche, F.-N.; Yassaa, N.

2018-03-01

The use of inexpensive biological materials, such as marine algae for removing dyes from contaminated industrial effluents appears as a potential alternative method. The aim of this study is to investigate the aptitude of marine macroalgae Posidonia Oceanica local biomass abundant on the coasts of Algeria for selective sorption of methylene blue (MB) from an aqueous solution in batch experiments at 20 °C. A maximum percentage removal of Posidonia oceanica occurs at pH 5. Equilibrium isotherm data were analyzed using the Langmuir and the Freundlich isotherms. The adsorption equilibrium of methylene blue was best describe by Langmuir model than the Freundlich model. The maximum sorption capacity was 357 mgg-1at pH 5. The sorption data were very well described by the pseudo-second-order model. Keywords: Posidonia oceanica, Methylene blue (MB), Biosorption, Isotherm Equilibrium, Kinetics; Modelling.

Ion adsorption parameters determined from zeta potential and titration data for a gamma-alumina nanofiltration membrane

NARCIS (Netherlands)

Samuel de Lint, W.B.; Benes, N.E.; Lyklema, J.; Bouwmeester, H.J.M.; Linde, van der A.J.; Wessling, M.

2003-01-01

Theoretical models for the prediction of nanofiltration separation performance as a function of, e.g., pH and electrolyte composition require knowledge on the ion-surface adsorption chemistry. Adsorption parameters have been extracted from electrophoretic mobility measurements on a ceramic -alumina

Adsorption of dodecylamine hydrochloride on graphene oxide in water

Science.gov (United States)

Chen, Peng; Li, Hongqiang; Song, Shaoxian; Weng, Xiaoqing; He, Dongsheng; Zhao, Yunliang

Cationic surfactants in water are difficult to be degraded, leading to serious water pollution. In this work, graphene oxide (GO) was used as an adsorbent for removing Dodecylamine Hydrochloride (DACl), a representative cationic surfactant. X-ray diffraction (XRD), FT-IR spectroscopy and atomic force microscope (AFM) were used to characterize the prepared GO. The adsorption of DACl on GO have been investigated through measurements of adsorption capacity, zeta potential, FTIR, and X-ray photoelectron spectroscopy (XPS). The experimental results have shown that the adsorption kinetics could be described as a rate-limiting pseudo second-order process, and the adsorption isotherm agreed well with the Freundlich model. GO was a good adsorbent for DACl removal, compared with coal fly ash and powdered activated carbon. The adsorption process was endothermic, and could be attributed to electrostatic interaction and hydrogen bonding between DACl and GO.

Dispersion stability of a ceramic glaze achieved through ionic surfactant adsorption.

Science.gov (United States)

Panya, Preecha; Arquero, Orn-anong; Franks, George V; Wanless, Erica J

2004-11-01

The adsorption of cetylpyridinium chloride (CPC) and sodium dodecylbenzenesulfonate (SDBS) onto a ceramic glaze mixture composed of limestone, feldspar, quartz, and kaolin has been investigated. Both adsorption isotherms and the average particle zeta potential have been studied in order to understand the suspension stability as a function of pH, ionic strength, and surfactant concentration. The adsorption of small amounts of cationic CPC onto the primarily negatively charged surfaces of the particles at pH 7 and 9 results in strong attraction and flocculation due to hydrophobic interactions. At higher surfactant concentrations a zeta potential of more than +60 mV results from the bilayered adsorbed surfactant, providing stability at salt concentrations dispersion or hydrophobic interactions, the magnitude of the negative zeta potential increases slightly. At pH 9 this increase is enough to promote stability with an average zeta potential of more than -55 mV, whereas at pH 7 the zeta potential is lower at about -45 mV. The stability of suspensions at pH 7 is additionally due to steric repulsion caused by the adsorption of thick layers of neutrally charged Ca(DBS)2 complexes created when the surfactant interacts with dissolved calcium ions from the calcium carbonate component.

Ion Adsorption Parameters Determined from Zeta Potential and Titration Data for a y-Alumina Nanofiltration Membrane

NARCIS (Netherlands)

de Lint, W.B.S.; Benes, Nieck Edwin; Lyklema, Johannes; Bouwmeester, Henricus J.M.; van der Linde, Ab J.; Wessling, Matthias

2003-01-01

Theoretical models for the prediction of nanofiltration separation performance as a function of, e.g., pH and electrolyte composition require knowledge on the ion-surface adsorption chemistry. Adsorption parameters have been extracted from electrophoretic mobility measurements on a ceramic y-alumina

Effective adsorption of malachite green using magnetic barium phosphate composite from aqueous solution

Science.gov (United States)

Zhang, Fan; Wei, Zhong; Zhang, Wanning; Cui, Haiyan

2017-07-01

Magnetic Ba3(PO4)2/Fe3O4-nanoparticle (called BPFN) was prepared, characterized, and developed as a low-cost adsorbent for malachite green (MG) from aqueous solution. Factors such as adsorption temperature, pH of solution, dosage of adsorbent, adsorption kinetics and isotherms were investigated. The maximum adsorption capacity obtained in this work was 1639 mg g- 1 at 45 °C and pH 6. The adsorption process fitted the pseudo-first-order kinetic model and Langmuir isotherm model. Evidences from zeta potential, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) data revealed that the adsorption process was driven by electrostatic attraction, the interaction between Lewis base sbnd N(CH3)2 in MG and Lewis acid Ba sites of BPFN. In addition, the BPFN could be easily regenerated by a magnet and the adsorption capacity maintained at 70% after five cycles. The present study suggests that the BPFN had high potential of removing MG from wastewater.

Hydrogen adsorption on and solubility in graphites

International Nuclear Information System (INIS)

Kanashenko, S.L.; Wampler, W.R.

1996-01-01

The experimental data on adsorption and solubility of hydrogen isotopes in graphite over a wide range of temperatures and pressures are reviewed. Langmuir adsorption isotherms are proposed for the hydrogen-graphite interaction. The entropy and enthalpy of adsorption are estimated, allowing for effects of relaxation of dangling sp 2 bonds. Three kinds of traps are proposed: edge carbon atoms of interstitial loops with an adsorption enthalpy relative to H 2 gas of -4.4 eV/H 2 (unrelaxed, Trap 1), edge carbon atoms at grain surfaces with an adsorption enthalpy of -2.3 eV/H 2 (relaxed, Trap 2), and basal plane adsorption sites with an enthalpy of +2.43 eV/H 2 (Trap 3). The adsorption capacity of different types of graphite depends on the concentration of traps which depends on the crystalline microstructure of the material. The number of potential sites for the 'true solubility' (Trap 3) is assumed to be about one site per carbon atom in all types of graphite, but the endothermic character of this solubility leads to a negligible H inventory compared to the concentration of hydrogen in type 1 and type 2 traps for temperatures and gas pressures used in the experiments. Irradiation with neutrons or carbon atoms increases the concentration of type 1 and type 2 traps from about 20 and 200 appm respectively for unirradiated (POCO AXF-5Q) graphite to about 1500 and 5000 appm, respectively, at damage levels above 1 dpa. (orig.)

Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation

OpenAIRE

Chen, Qing; Tian, Yuanyuan; Li, Peng; Yan, Changhui; Pang, Yu; Zheng, Li; Deng, Hucheng; Zhou, Wen; Meng, Xianghao

2017-01-01

Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indi...

Effects of Capillary Forces and Adsorption on Reserves Distribution

DEFF Research Database (Denmark)

Shapiro, Alexander; Stenby, Erling Halfdan

1996-01-01

The purpose of this study is to evaluate the effects of capillary forces and adsorption on the distribution of a hydrocarbon mixture in an oil-gas-condensate reservoir. These effects consist in the precipitation of the liquid phase in thin pores and on the internal surface of the reservoir rock....... To estimate the amount of the dispersed liquid condensate, analytical methods based on the generalization of the Kelvin equation and on the potential theory of adsorption have been developed. Sample calculations show significant role of adsorption, especially, in the neighborhood of the critical point...

Adsorption of CO2 and H2O on supported amine sorbents

NARCIS (Netherlands)

Veneman, Rens; Zhao, W.; Li, Z.; Cai, N.; Brilman, Derk Willem Frederik

2014-01-01

In this work we have evaluated the H2O and CO2 adsorption characteristics of Lewatit VP OC 1065 in view of the potential application of solid sorbents in post combustion CO2 capture. Here we present single component adsorption isotherms for H2O and CO2 as well as co-adsorption experiments. It was

Hydrogen adsorption in metal-decorated silicon carbide nanotubes

Science.gov (United States)

Singh, Ram Sevak; Solanki, Ankit

2016-09-01

Hydrogen storage for fuel cell is an active area of research and appropriate materials with excellent hydrogen adsorption properties are highly demanded. Nanotubes, having high surface to volume ratio, are promising storage materials for hydrogen. Recently, silicon carbide nanotubes have been predicted as potential materials for future hydrogen storage application, and studies in this area are ongoing. Here, we report a systematic study on hydrogen adsorption properties in metal (Pt, Ni and Al) decorated silicon carbide nanotubes (SiCNTs) using first principles calculations based on density functional theory. The hydrogen adsorption properties are investigated by calculations of adsorption energy, electronic band structure, density of states (DOS) and Mulliken charge population analysis. Our findings show that hydrogen adsorptions on Pt, Ni and Al-decorated SiCNTs undergo spontaneous exothermic reactions with significant modulation of electronic structure of SiCNTs in all cases. Importantly, according to the Mulliken charge population analysis, dipole-dipole interaction causes chemisorptions of hydrogen in Pt, Ni and Al decorated SiCNTs with formation of chemical bonds. The study is a platform for the development of metal decorated SiCNTs for hydrogen adsorption or hydrogen storage application.

SeO2 adsorption on CaO surface: DFT study on the adsorption of a single SeO2 molecule

Science.gov (United States)

Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu; Li, Liangliang

2017-08-01

Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO2 in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO2 due to its low cost. In this paper, the adsorption mechanisms of single SeO2 on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO2 on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O2 atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO2 and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

Adsorptive storage of natural gas

International Nuclear Information System (INIS)

Yan, Song; Lang, Liu; Licheng, Ling

2001-01-01

The Adsorbed Natural Gas (ANG) storage technology is reviewed. The present status, theoretical limits and operational problems are discussed. Natural gas (NG) has a considerable advantage over conventional fuels both from an environmental point of view and for its natural abundance. However, as well known, it has a two fold disadvantage compared with liquid fuels: it is relatively expensive to transport from the remote areas, and its energy density (heat of combustion/volume) is low. All these will restrict its use. Compressed natural gas (CNG) may be a solution, but high pressures are needed (up to 25 MPa) for use in natural-gas fueled vehicles, and the large cost of the cylinders for storage and the high-pressure facilities necessary limit the practical use of CNG. Alternatively, adsorbed natural gas (ANG) at 3 - 4 MPa offers a very high potential for exploitation in both transport and large-scale applications. At present, research about this technology mainly focuses on: to make adsorbents with high methane adsorption capacity; to make clear the effects of heat of adsorption and the effect of impurities in natural gas on adsorption and desorption capacity. This paper provides an overview of current technology and examines the relations between fundamentals of adsorption and ANG storage. (authors)

Insight into the adsorption of chloramphenicol on a vermiculite surface

Science.gov (United States)

Tri, Nguyen Ngoc; Carvalho, A. J. P.; Dordio, A. V.; Nguyen, Minh Tho; Trung, Nguyen Tien

2018-05-01

Four stable configurations were found upon adsorption of the chloramphenicol on a period slab model of the vermiculite surface, using the PBE and C09-vdW functionals in a projector-augmented wave (PAW) method approach. The adsorption is a strong chemisorption process, characterized by an adsorption energy of -106.5 kcal mol-1 at the most stable configuration. Stability of configurations contributed mainly by Mg⋯O/Cl attractive electrostatic interactions and C/Osbnd H⋯O hydrogen bonds. It is remarkable that the vermiculite is found to be a solid material with good potential to be used for adsorption and consequent removal of this type of antibiotic drugs.

Isotope effect in monolayer, localised, immobilised adsorption with special reference to neon adsorption on porous glass at cryogenic temperatures

International Nuclear Information System (INIS)

Srisaila, S.; Bajpai, M.B.

1980-01-01

Using statistical mechanics, a general formula for the separation factor of two isotopes between gas and adsorbate phases in a monolayer, localised, immobile adsorption on a heterogeneous surface, is derived. Special forms of this are discussed for which the familiar Bigeleisen form is one. Purer, Kalplan and Smith, in their work on neon isotopes separation by gas chromatography through porous glass column at cryogenic temperatures, have reported that the separation factor first increased and then decreased as the temperature was decreased, whereas monotonic increase was the normally expected behaviour. Moiseyev has attempted to explain the anomaly after assuming two types of adsorption sites. The present theory gives the conditions in which monotonic and nonmonotonic variations can occur and after making some assumptions, the experimental curve of Purer et al could be reproduced computationally using one form of the general expression. This theoretical treatment highlights the importance of both potential energy and force constant in isotope effect whereas it is only the potential energy that is much involved in most adsorption studies. (auth.)

SeO{sub 2} adsorption on CaO surface: DFT study on the adsorption of a single SeO{sub 2} molecule

Energy Technology Data Exchange (ETDEWEB)

Fan, Yaming; Zhuo, Yuqun; Lou, Yu; Zhu, Zhenwu [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Li, Liangliang [Key Laboratory of Advanced Materials, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)

2017-08-15

Highlights: • Adsorption mechanisms of SeO{sub 2} on CaO surface under O{sub 2} were firstly studied by DFT. • The adsorption energies, bond length and electron density maps were calculated. • The electronic structure changes upon adsorption were studied. - Abstract: Selenium is a hazardous element in coal. During coal combustion, most of the selenium will convert to SeO{sub 2} in the flue gas. Ca-based adsorbents, especially CaO, have been considered as a potential sorbent to adsorb SeO{sub 2} due to its low cost. In this paper, the adsorption mechanisms of single SeO{sub 2} on CaO surface were investigated by density functional theory (DFT) calculation. Both the physisorption and chemisorption structures were determined. It has been identified that the adsorption of SeO{sub 2} on CaO surface is primarily chemisorption, while physisorption takes effects at the initial stage of the process. Under O{sub 2} atmosphere, selenate is hard to form. Most of the adsorption products are selenite. Additionally, the electron density maps were obtained to reveal the surface active sites. The partial density of states (PDOS) was calculated for analyzing the electronic structural change of SeO{sub 2} and CaO surface during adsorption. The results provide fundamental information of the adsorption process, which could be meaningful for the development of new absorbents.

A DFT study of hydrogen adsorption on Be, Mg and Ca frameworks in erionite zeolite

Energy Technology Data Exchange (ETDEWEB)

Fellah, Mehmet Ferdi, E-mail: mferdi.fellah@btu.edu.tr

2017-02-01

Highlights: • Mg-ERI and Ca-ERI clusters have much lower chemical potential and hardness. • Adsorption enthalpies for Mg- and Ca-ERI are importantly greater than the liquefaction enthalpy of hydrogen. • Mg-ERI and Ca-ERI clusters have much HOMO-LUMO gap indicating higher reactivity. • Ca- and Mg-ERI are potential cryoadsorbent materials for hydrogen storage. - Abstract: The molecular hydrogen adsorption was investigated on additional frameworks with earth alkaline metal atoms (Be, Mg and Ca) in 24T ERI zeolite cluster model by means of Density Functional Theory study. HOMO and LUMO energy values, chemical potential, chemical hardness, electronegativity, adsorption energy and adsorption enthalpy values have been calculated in this study. Mg-ERI and Ca-ERI clusters have much lower chemical potentials with much lower adsorption energy values when compared to the value of Be-ERI cluster. Additionally, they are softer than Be-ERI cluster with respect to their lower chemical hardness values. Hydrogen adsorption enthalpy values were computed as −3.6 and −3.9 kJ/mol on Mg-ERI and Ca-ERI clusters, respectively. These adsorption enthalpy values are significantly larger than the enthalpy value of liquefaction for hydrogen molecule. This consequently specifies that Mg-ERI and Ca-ERI zeolite structures which have higher chemical reactivity appear to be a promising candidate cryoadsorbent for hydrogen storage.

Increased adsorption of histidine-tagged proteins onto tissue culture polystyrene.

Science.gov (United States)

Holmberg, Maria; Hansen, Thomas Steen; Lind, Johan Ulrik; Hjortø, Gertrud Malene

2012-04-01

In this study we compare histidine-tagged and native proteins with regards to adsorption properties. We observe significantly increased adsorption of proteins with an incorporated polyhistidine amino acid motif (HIS-tag) onto tissue culture polystyrene (TCPS) compared to similar proteins without a HIS-tag. The effect is not observed on polystyrene (PS). Adsorption experiments have been performed at physiological pH (7.4) and the effect was only observed for the investigated proteins that have pI values below or around 7.4. Competitive adsorption experiments with imidazole and ethylenediaminetetraacetic acid (EDTA), as well as adsorption performed at different pH and ionic strength indicates that the high adsorption is caused by electrostatic interaction between negatively charged carboxylate groups on the TCPS surface and positively charged histidine residues in the proteins. Pre-adsorption of bovine serum albumin (BSA) does not decrease the adsorption of HIS-tagged proteins onto TCPS. Our findings identify a potential problem in using HIS-tagged signalling molecule in assays with cells cultured on TCPS, since the concentration of the molecule in solution might be affected and this could critically influence the assay outcome. Copyright © 2011 Elsevier B.V. All rights reserved.

Adsorption of hydrogen in Scandium/Titanium decorated nitrogen doped carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Mananghaya, Michael, E-mail: mikemananghaya@gmail.com [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines); DOST-ASTHRDP, PCIEERD, Gen. Santos Ave., Bicutan, Taguig City 1631 (Philippines); Belo, Lawrence Phoa; Beltran, Arnel [De La Salle University, 2401 Taft Ave, 0922, Manila (Philippines); DLSU STC Laguna Boulevard, LTI Spine Road Barangays Biñan and Malamig, Biñan City, Laguna (Philippines)

2016-09-01

Nitrogen doped Carbon Nanotube with divacancy (4ND-CN{sub x}NT) that is decorated with Scandium and Titanium as potential hydrogen storage medium using the pseudo potential density functional method was investigated. Highly localized states near the Fermi level, which are derived from the nitrogen defects, contribute to strong Sc and Ti bindings, which prevent metal aggregation and improve the material stability. A detailed Comparison of the Hydrogen adsorption capability with promising system-weight efficiency of Sc over Ti was elucidated when functionalized with 4ND-CN{sub x}NT. Finally, the (Sc/4ND){sub 10}-CN{sub x}CNT composite material has a thermodynamically favorable adsorption and consecutive adsorption energy for ideal reversible adsorption and desorption of hydrogen at room temperature such that it can hold at least 5.8 wt% hydrogen molecules at the LDA and GGA level. - Highlights: • Carbon Nanotube with divacancy (4ND-CN{sub x}NT) decorated with Sc and Ti. • Nitrogen defects, contribute to strong Sc and Ti bindings. • H{sub 2} and (Sc/4ND){sub 10}-CN{sub x}CNT has a favorable adsorption. • 5.8 wt% adsorption at the LDA and GGA level.

Mesoporous hydroxyapatite: Preparation, drug adsorption, and release properties

Energy Technology Data Exchange (ETDEWEB)

Gu, Lina; He, Xiaomei; Wu, Zhenyu, E-mail: zhenyuwuhn@sina.com

2014-11-14

Mesoporous hydroxyapatite (HA) was synthesized through gas–liquid chemical precipitation method at ambient temperature without any template. Structure, morphology and pore size distribution of HA were analyzed via X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution electron microscopy and N{sub 2} adsorption/desorption. The chemotherapeutic agent doxorubicin (DOX) was used to investigate the drug adsorption and release behavior of HA. The kinetics of DOX adsorption on HA followed the pseudo-second-order rate expression. Adsorption isotherms at various temperatures were obtained, and the equilibrium data fitted the Langmuir model. The values of thermodynamic parameters (Gibbs free energy, entropy, and enthalpy changes) demonstrated that the adsorption process was spontaneous and endothermic. In vitro pH-responsive (pH = 7.4, 5.8) controlled release was investigated. DOX-loaded HA showed a slow, long-term, and steady release rate. The release rate at pH5.8 was larger than that at pH7.4. Consequently, the as-prepared mesoporous HA has potential applications in controlled drug delivery systems. - Highlights: • Mesoporous HA was synthesized by a simple precipitation method without any template. • The kinetics of adsorption followed the pseudo-second-order rate expression. • Thermodynamics investigation showed that adsorption was spontaneous and endothermic. • DOX-loaded HA showed a long-term, steady, and pH-controlled release rate.

Depth distribution of 137Cs adsorption property of clay minerals influenced by mineral weathering

International Nuclear Information System (INIS)

Nakao, Atsushi; Funakawa, Shinya; Kosaki, Takashi

2007-01-01

Radiocesium adsorption potential of mica clay mineral can increase as it is weathered, because K depletion in mica interlayer sites generates new Cs selective sites. However, in soils weathered under field conditions, the increase in 137 Cs adsorption potential associated with mineral weathering has not been observed extensively. We investigated four soil profiles from Japan and Thailand with different soil pH ranges (3.3-4.0, 4.2-4.3, 5.0-5.7, and 5.5-7.3). The solid/liquid distribution coefficients of Cs ( Cs Kd) in clay ( 137 Cs adsorption potential of mica clay minerals. In three soil profiles, Cs Kd value in clay was the largest at a surface horizon and was decreased with depth, whereas in the most acidic of Podzolic soil profile, it was the largest at B horizon. The large Cs Kd value in surface clays relative to deeper horizons were well associated with that of 2.0-1.0 μm clay fraction. We assumed that the 137 Cs adsorption potential increased at surface horizons mainly because coarser clay micas were weathered and generated Cs selective sites. The exceptional result obtained in Podzolic soil profile suggests that too intensive weathering destruct mica structure and may decrease in Cs adsorption potential of mica clay minerals. (author)

Adsorption and co-adsorption of graphene oxide and Ni(II) on iron oxides: A spectroscopic and microscopic investigation.

Science.gov (United States)

Sheng, Guodong; Huang, Chengcai; Chen, Guohe; Sheng, Jiang; Ren, Xuemei; Hu, Baowei; Ma, Jingyuan; Wang, Xiangke; Huang, Yuying; Alsaedi, Ahmed; Hayat, Tasawar

2018-02-01

Graphene oxide (GO) may strongly interact with toxic metal ions and mineral particles upon release into the soil environment. We evaluated the mutual effects between GO and Ni (Ni(II)) with regard to their adsorption and co-adsorption on two minerals (goethite and hematite) in aqueous phase. Results indicated that GO and Ni could mutually facilitate the adsorption of each other on both goethite and hematite over a wide pH range. Addition of Ni promoted GO co-adsorption mainly due to the increased positive charge of minerals and cation-π interactions, while the presence of GO enhanced Ni co-adsorption predominantly due to neutralization of positive charge and strong interaction with oxygen-containing functional groups on adsorbed GO. Increasing adsorption of GO and Ni on minerals as they coexist may thus reduce their mobility in soil. Extended X-ray absorption fine structure (EXAFS) spectroscopy data revealed that GO altered the microstructure of Ni on minerals, i.e., Ni formed edge-sharing surface species (at R Ni-Fe ∼3.2 Å) without GO, while a GO-bridging ternary surface complexes (at R Ni-C ∼2.49 Å and R Ni-Fe ∼4.23 Å) was formed with GO. These findings improved the understanding of potential fate and toxicity of GO as well as the partitioning processes of Ni ions in aquatic and soil environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption of Phosphate Ion in Water with Lithium-Intercalated Gibbsite

Directory of Open Access Journals (Sweden)

Riwandi Sihombing

2015-12-01

Full Text Available In order to enhance adsorption capacity of gibbsite (Al(OH3 as an adsorbent for the adsorption of phosphate in water, gibbsite was modified through lithium-intercalation. The purification method of Tributh and Lagaly was applied prior to intercalation. The Li-Intercalation was prepared by the dispersion of gibbsite into LiCl solution for 24 hours. This intercalation formed an cationic clay with the structure of [LiAl2(OH6]+ and exchangeable Cl- anions in the gibbsite interlayer. A phosphate adsorption test using Lithium-intercalated gibbsite (LIG resulted in optimum adsorption occurring at pH 4.5 with an adsorption capacity of 11.198 mg phosphate/g LIG which is equivalent with 1.04 wt% LIG. The adsorption capacity decreased with decreasing amounts of H2PO4-/HPO4- species in the solution. This study showed that LIG has potential as an adsorbent for phosphate in an aqueous solution with pH 4.5–9.5.

Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

International Nuclear Information System (INIS)

Hassan, H.Z.; Mohamad, A.A.; Al-Ansary, H.A.; Alyousef, Y.M.

2014-01-01

The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling

Water adsorption on goethite: Application of multilayer adsorption models

Science.gov (United States)

Hatch, C. D.; Tumminello, R.; Meredith, R.

2016-12-01

Adsorbed water on the surface of atmospheric mineral dust has recently been shown to significantly affect the ability of mineral dust aerosol to act as cloud condensation nuclei. We have studied water adsorption as a function of relative humidity (RH) on goethite (α-FeO(OH)), a common component of atmospheric mineral dust. The goethite surface area and particle size was determined using BET analysis and with N2 as an adsorbate and scanning electron microscopy, respectively. Water adsorption on the sample was monitored using horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy equipped with a flow cell. Water content was determined using Beer's law and the optical constants for bulk water. The results were analyzed using Type II adsorption isotherms to model multilayer adsorption, including BET (Brunauer, Emmet and Teller), FHH (Frenkel, Halsey and Hill) and Freundlich. BET fits to experimental data provide parameters of monolayer coverage, while the FHH and Freundlich isotherms provide insights into multilayer adsorption mechanisms. Results indicate that goethite contains 5% H2O by mass at 50% RH, which increases to 12% by mass at 90% RH. Adsorption parameters and experimental results will be presented.

Adsorption of emerging contaminant metformin using graphene oxide.

Science.gov (United States)

Zhu, Shuai; Liu, Yun-Guo; Liu, Shao-Bo; Zeng, Guang-Ming; Jiang, Lu-Hua; Tan, Xiao-Fei; Zhou, Lu; Zeng, Wei; Li, Ting-Ting; Yang, Chun-Ping

2017-07-01

The occurrence of emerging contaminants in our water resources poses potential threats to the livings. Due to the poor treatment in wastewater management, treatment technologies are needed to effectively remove these products for living organism safety. In this study, Graphene oxide (GO) was tested for the first time for its capacity to remove a kind of emerging wastewater contaminants, metformin. The research was conducted by using a series of systematic adsorption and kinetic experiments. The results indicated that GO could rapidly and efficiently reduce the concentration of metformin, which could provide a solution in handling this problem. The uptake of metformin on the graphene oxide was strongly dependent on temperature, pH, ionic strength, and background electrolyte. The adsorption kinetic experiments revealed that almost 80% removal of metformin was achieved within 20 min for all the doses studied, corresponding to the relatively high k 1 (0.232 min -1 ) and k 2 (0.007 g mg -1  min -1 ) values in the kinetic models. It indicated that the highest adsorption capacity in the investigated range (q m ) of GO for metformin was at pH 6.0 and 288 K. Thermodynamic study indicated that the adsorption was a spontaneous (ΔG 0  adsorption of metformin increased when the pH values changed from 4.0 to 6.0, and decreased adsorption were observed at pH 6.0-11.0. GO still exhibited excellent adsorption capacity after several desorption/adsorption cycles. Besides, both so-called π-π interactions and hydrogen bonds might be mainly responsible for the adsorption of metformin onto GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intensify dodecylamine adsorption on magnesite and dolomite surfaces by monohydric alcohols

Science.gov (United States)

Zhang, Hao; Liu, Wengang; Han, Cong; Wei, Dezhou

2018-06-01

The flotation of magnesite and dolomite were investigated with the presence of single dodecylamine (DDA) and combined mixtures of DDA and monohydric alcohols, respectively. The adsorption behavior of DDA, butanol, hexanol and octanol on the surface of the two minerals were shown by molecular dynamics simulation, and the results were corresponding with the analysis of zeta potential, measurements of the contact angle and adsorption. Flotation results indicated that part of DDA could be replaced by the three alcohols (butanol, hexanol, octanol) to get better flotation results. Molecular dynamics simulation and the results of zeta potential and contact angle measurements indicated that adsorption of DDA on mineral surfaces could be strengthened by monohydric alcohols.

Direct measurements of adsorption heats of hydrogen on nano-porous carbons

International Nuclear Information System (INIS)

Akihiko, Matsumoto; Kazumasa, Yamamoto; Tomoyuki, Miyata

2005-01-01

. The adsorption amounts at ca.10 MPa were 0.5 - 0.8 mass %, as exemplified in Figure 1 for A7, but the uptake per unit area for A7 is higher than that of A20, suggesting higher sorptivity on ACF of narrower pore size. In the case of adsorption in narrower micropores of A7, overlapping of the force fields of faced pore walls enhances the potential field in the micropore, and the enhancement is 1.75-fold [2-4]. This potential enhancement would bring about higher sorptivity of hydrogen. Differential heats of adsorption on A7 were shown in Figure 2. The adsorption heats were 4 to 6 kJ/mol regardless of adsorption temperature, which agrees with calculated value based upon dispersion interaction (van der Waals interaction). Isosteric heats of adsorption were estimated from the adsorption isotherms by the Clausius-Clapeyron equation and they agreed well with the experimental results. These results suggest that hydrogen adsorption takes place even over critical temperature by dispersion interaction, and the pore width would play an important role in the sorptivity. [1] A. C. Dillon et al., Nature, 386, 377, 1997. [2] D.H. Everett and J.C. Powl, J. Chem. Soc., Faraday Trans. 1, 72, 619, 1976. [3] K. Kaneko, R.F. Cracknell, D. Nicholson, Langmuir, 10, 4606, 1994 [4] A. Matsumoto, J. Zhao, K. Tsutsumi, Langmuir, 13, 496, 1997. (authors)

Adsorption study of Ammonia Nitrogen by watermelon rind

Science.gov (United States)

Ibrahim, A.; Yusof, L.; Beddu, N. S.; Galasin, N.; Lee, P. Y.; Lee, R. N. S.; Zahrim, A. Y.

2016-06-01

The utilization of fruit waste for low-cost adsorbents as a replacement for costly conventional methods of removing ammonia nitrogen from wastewater has been reviewed. The adsorption studies were conducted as a function of contact time and adsorbent dosage and it were carried out on four different adsorbents; fresh watermelon rind and modified watermelon rind with sodium hydroxide (NaOH), potassium hydroxide (KOH) and sulphuric acid (H2SO4). Adsorbents were tested for characterization by using zeta potential test and all samples shows negative values thus makes it favourable for the adsorption process. The batch experimental result showed that adsorption process is rapid and equilibrium was established within 40 minutes of contact time. The ammonia nitrogen removal rate amounted in range of 96% to 99%, and the adsorption capacities were in range of 1.21 to 1.24 mg/g for all four different types of adsorbents used.

Removal of furan and phenolic compounds from simulated biomass hydrolysates by batch adsorption and continuous fixed-bed column adsorption methods.

Science.gov (United States)

Lee, Sang Cheol; Park, Sunkyu

2016-09-01

It has been proposed to remove all potential inhibitors and sulfuric acid in biomass hydrolysates generated from dilute-acid pretreatment of biomass, based on three steps of sugar purification process. This study focused on its first step in which furan and phenolic compounds were selectively removed from the simulated hydrolysates using activated charcoal. Batch adsorption experiments demonstrated that the affinity of activated charcoal for each component was highest in the order of vanillic acid, 4-hydroxybenzoic acid, furfural, acetic acid, sulfuric acid, and xylose. The affinity of activated charcoal for furan and phenolic compounds proved to be significantly higher than that of the other three components. Four separation strategies were conducted with a combination of batch adsorption and continuous fixed-bed column adsorption methods. It was observed that xylose loss was negligible with near complete removal of furan and phenolic compounds, when at least one fixed-bed column adsorption was implemented in the strategy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Probing Gas Adsorption in Zeolites by Variable-Temperature IR Spectroscopy: An Overview of Current Research.

Science.gov (United States)

Garrone, Edoardo; Delgado, Montserrat R; Bonelli, Barbara; Arean, Carlos O

2017-09-15

The current state of the art in the application of variable-temperature IR (VTIR) spectroscopy to the study of (i) adsorption sites in zeolites, including dual cation sites; (ii) the structure of adsorption complexes and (iii) gas-solid interaction energy is reviewed. The main focus is placed on the potential use of zeolites for gas separation, purification and transport, but possible extension to the field of heterogeneous catalysis is also envisaged. A critical comparison with classical IR spectroscopy and adsorption calorimetry shows that the main merits of VTIR spectroscopy are (i) its ability to provide simultaneously the spectroscopic signature of the adsorption complex and the standard enthalpy change involved in the adsorption process; and (ii) the enhanced potential of VTIR to be site specific in favorable cases.

Rapid and tunable selective adsorption of dyes using thermally oxidized nanodiamond.

Science.gov (United States)

Molavi, Hossein; Shojaei, Akbar; Pourghaderi, Alireza

2018-03-27

In the present study, capability of nanodiamond (ND) for the adsorption of anionic (methyl orange, MO) and cationic (methylene blue, MB) dyes from aqueous solution was investigated. Employing fourier transform infrared (FTIR) spectroscopy, Boehm titration method and zeta potential, it was found that the simple thermal oxidation of ND at 425 °C, increased the content of carboxylic acid of ND and accordingly the zeta potential of ND decreased considerably. Therefore, a series of oxidized NDs (OND) at various oxidation times and as-received untreated ND (UND) was used as adsorbents of MO and MB. The adsorption experiments exhibited that UND had large adsorption capacity, very fast adsorption kinetics and excellent selectivity for MO over MB. These results suggested that the adsorption tendency of UND toward anionic MO dye followed not only by electrostatic interactions but also via the chemical interaction caused by the strong hydrogen bond between the sulfonate groups of MO and the oxygen containing groups on the surface of UND. In contrast, ONDs exhibited higher adsorption capacity for cationic MB whose tendency toward MB increased by increasing the thermal oxidation time due to the promotion of the negative charge on the surface of OND leading to the higher electrostatic attraction. The adsorption rate of MB on ONDs was also very high. Kinetics data was well fitted with the pseudo- second-order model for most of the adsorbents. The adsorption selectivity analysis revealed that ONDs displayed more adsorption capacity for MB compared with MO which was also attributed to high electrostatic interactions of cationic dye with negative charges of ONDs. Finally, the release behavior of NDs was also demonstrated after soaking in ethanol and acetone. Copyright © 2018 Elsevier Inc. All rights reserved.

Treatment of aqueous diethyl phthalate by adsorption using a functional polymer resin.

Science.gov (United States)

Xu, Zhengwen; Zhang, Weiming; Pan, Bingcai; Lv, Lu; Jiang, Zhengmao

2011-01-01

To study the adsorptive separation efficiency, adsorption and desorption performances of diethyl phthalate (DEP) were investigated with a functional polymer resin (NDA-702). A macroporous polymer resin (XAD-4) and a coal-based granular activated carbon (AC-750) were chosen for comparison. The kinetic adsorption data obeyed the pseudo-second-order rate model, and the adsorption processes were limited by both film and intraparticle diffusions. Adsorption equilibrium data were well fitted by the Freundlich equation, and the larger uptake and higher selection of NDA-702 than AC-750 and XAD-4 was probably due to the microporous structure, phenyl rings and polar groups on NDA-702. Thermodynamic adsorption studies indicated that the test adsorbents spontaneously adsorbed DEP, driven mainly by enthalpy change. Continuous fixed-bed runs demonstrated that there no significant loss of the resin's adsorption capacity and there was complete regeneration of NDA-702. The results suggest that NDA-702 has excellent potential as an adsorption material for water treatment.

Adsorptive removal of bisphenol A using synthesized magnetite nanoparticles

Science.gov (United States)

Orimolade, B. O.; Adekola, F. A.; Adebayo, G. B.

2018-03-01

Bisphenol A (BPA) is an organic compound which is often used as plasticizer and has been reported to be hazardous to man. In this research the efficiency of removal of BPA from water by magnetite through adsorption process was studied. The magnetite was synthesized using reverse co-precipitation method and fully characterized. Various physicochemical parameters affecting the adsorption of BPA using magnetite were studied as well. The optimum time for the adsorption process was found to be 60 min at pH of 6, adsorbent dose of 0.2 g and 50 ppm of BPA. The adsorption data were fitted by the Langmuir adsorption isotherm best with a regression value of 0.957. The R L value was 0.179 which revealed that the process is favorable. The Freundlich constant n which was 1.901 also revealed that the adsorption is normal and favorable. The data were in agreement with the pseudo-second-order kinetics with regression value of 0.98. From the thermodynamic studies, the process was found to be exothermic and the Gibb's free energy value which was negative showed that the adsorption was spontaneous. The synthesized magnetite therefore offers great potential for the remediation of bisphenol A-contaminated media.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite.

Directory of Open Access Journals (Sweden)

Yajun Chen

Full Text Available Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR and ciprofloxacin (CIP, by nano-hydroxyapatite (n-HAP were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g · L(-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics.

Adsorptive Removal and Adsorption Kinetics of Fluoroquinolone by Nano-Hydroxyapatite

Science.gov (United States)

Chen, Yajun; Lan, Tao; Duan, Lunchao; Wang, Fenghe; Zhao, Bin; Zhang, Shengtian; Wei, Wei

2015-01-01

Various kinds of antibiotics, especially fluoroquinolone antibiotics (FQs) have been widely used for the therapy of infectious diseases in human and livestock. For their poorly absorbed by living organisms, large-scale misuse or abuse of FQs will foster drug resistance among pathogenic bacteria, as well as a variety of environmental problems when they were released in the environment. In this work, the adsorption properties of two FQs, namely norfloxacin (NOR) and ciprofloxacin (CIP), by nano-hydroxyapatite (n-HAP) were studied by batch adsorption experiments. The adsorption curves of FQs by n-HAP were simulated by Langmuir and Freundlich isotherms. The results shown that NOR and CIP can be adsorbed effectively by the adsorbent of n-HAP, and the adsorption capacity of FQs increase with increasing dosage of n-HAP. The optimum dosage of n-HAP for FQs removal was 20 g·L-1, in which the removal efficiencies is 51.6% and 47.3%, and an adsorption equilibrium time is 20 min. The maximum removal efficiency occurred when pH is 6 for both FQs. The adsorption isotherm of FQs fits well for both Langmuir and Freundlich equations. The adsorption of both FQs by n-HAP follows second-order kinetics. PMID:26698573

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

International Nuclear Information System (INIS)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-01-01

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

Energy Technology Data Exchange (ETDEWEB)

Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

2013-10-15

Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

Effects of carbon nanotubes on phosphorus adsorption behaviors on aquatic sediments.

Science.gov (United States)

Qian, Jin; Li, Kun; Wang, Peifang; Wang, Chao; Shen, Mengmeng; Liu, Jingjing; Tian, Xin; Lu, Bianhe

2017-08-01

Aquatic sediments are believed to be an important sink for carbon nanotubes (CNTs). With novel properties, CNTs can potentially disturb the fate and mobility of the co-existing contaminants in the sediments. Only toxic pollutants have been investigated previously, and to the best of our knowledge, no data has been published on how CNTs influence phosphorus (P) adsorption on aquatic sediments. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as model CNTs. Experimental results indicated that compared to pseudo-first order and intraparticle diffusion models, the pseudo-second-order model is better for describing the adsorption kinetics of sediments and MWCNT-contaminated sediments. Adsorption isotherm studies suggested that the Langmuir model fits the isotherm data well. With the increase in the MWCNT-to-sediment ratio from 0.0% to 5.0%, the theoretical maximum monolayer adsorption capacity (Q max ) for P increased from 0.664 to 0.996mg/g. However, the Langmuir isotherm coefficient (K L ) significantly decreased from 4.231L/mg to 2.874L/mg, indicating the decrease in the adsorption free energy of P adsorbed on the sediments after MWCNT contamination. It was suggested that P was released more easily to the overlying water after the re-suspension of sediments. Moreover, the adsorption of sediments and sediment-MWCNT mixture was endothermic and physical in nature. Results obtained herein suggested that the change in the specific surface area and zeta potential of sediments is related to MWCNT contamination, and the large adsorption capacity of MWCNTs is probably the main factor responsible for the variation in the adsorption of P on aquatic sediments. Copyright © 2017 Elsevier Inc. All rights reserved.

Langmuir and Freundlich Isotherm Adsorption Equations for Chromium (VI) Waste Adsorption by Zeolite

International Nuclear Information System (INIS)

Murni Handayani; Eko Sulistiyono

2009-01-01

The research of chromium (VI) waste adsorption by zeolite has done. Wastes which are produced by Industries, both radioactive waste and heavy metal waste need done more processing so that they are not endanger environment and human health. Zeolite has very well-ordered crystal form with cavity each other to way entirely so that cause surface wide of zeolite become very big and very good as adsorbents. This research intends to know appropriate isotherm adsorption method to determine maximum capacity of zeolite to chromium (VI) waste. The equations which used in adsorption process are Langmuir and Freundlich isotherm Adsorption equations. The instrument was used in adsorption process by using Atomic Adsorption Spectroscopy (AAS). The experiment result showed that the biggest mass of chromium (VI) metal ion which was absorb by zeolite in 20 ppm concentration was 7.71 mg/gram zeolite. Adsorption process of Chromium (VI) waste by zeolite followed Langmuir and Freundlich isotherm equations with R 2 >0,9 . Appropriate equation to determine maximum adsorption capacity of zeolite for chromium (VI) waste adsorption is Langmuir equation. The maximum adsorption capacity of zeolite is 52.25 mg/gram. (author)

Adsorption. What else?

OpenAIRE

Rodrigues, Alirio E.

2012-01-01

[EN] Chemical Engineering today combines Molecular and Materials Engineerig and Process and Product Engineering (ChE=M2P2). Cyclic adsorptive processes (Simulated Moving Bed –SMB and Pressure Swing Adsorption-PSA) will be discussed for “old” and “new” applications making use of “old” and “new” (MOFs) adsorbent materials. After revisiting my memory as PhD student and the First Brazilian Adsorption meeting I will review the basic concepts involved in adsorption processes and then...

Adsorption of antimony onto iron oxyhydroxides: Adsorption behavior and surface structure

Energy Technology Data Exchange (ETDEWEB)

Guo, Xuejun; Wu, Zhijun [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); He, Mengchang, E-mail: hemc@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Meng, Xiaoguang [Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Jin, Xin [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875 (China); Qiu, Nan; Zhang, Jing [Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

2014-07-15

Graphical abstract: - Highlights: • Antimony adsorption depended on the Sb species, pH, and the type of iron oxides. • Sb(V) adsorption favored at acidic pH, Sb(III) adsorption optimized in wider pH. • Antimony was adsorbed onto the iron oxides by the inner-sphere surface complex. • Bidentate mononuclear ({sup 2}E) was the dominant form of Sb incorporated into HFO. • XAFS and XPS indicated Sb(III) adsorbed was slowly oxidized to Sb(V). - Abstract: Antimony is detected in soil and water with elevated concentration due to a variety of industrial applications and mining activities. Though antimony is classified as a pollutant of priority interest by the United States Environmental Protection Agency (USEPA) and Europe Union (EU), very little is known about its environmental behavior and adsorption mechanism. In this study, the adsorption behaviors and surface structure of antimony (III/V) on iron oxides were investigated using batch adsorption techniques, surface complexation modeling (SCM), X-ray photon spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS). The adsorption isotherms and edges indicated that the affinity of Sb(V) and Sb(III) toward the iron oxides depended on the Sb species, solution pH, and the characteristics of iron oxides. Sb(V) adsorption was favored at acidic pH and decreased dramatically with increasing pH, while Sb(III) adsorption was constant over a broad pH range. When pH is higher than 7, Sb(III) adsorption by goethite and hydrous ferric oxide (HFO) was greater than Sb(V). EXAFS analysis indicated that the majority of Sb(III), either adsorbed onto HFO or co-precipitated by FeCl{sub 3}, was oxidized into Sb(V) probably due to the involvement of O{sub 2} in the long duration of sample preservation. Only one Sb–Fe subshell was filtered in the EXAFS spectra of antimony adsorption onto HFO, with the coordination number of 1.0–1.9 attributed to bidentate mononuclear edge-sharing ({sup 2}E) between Sb and

Evaluation of adsorption and Fenton-adsorption processes for landfill leachate treatment

OpenAIRE

San Pedro-Cedillo, L.; Méndez-Novelo, R.I.; Rojas-Valencia, M.N.; Barceló-Quintal, M.; Castillo-Borges, E.R.; Sauri-Riancho, M.R.; Marrufo-Gómez, J.M.

2015-01-01

The objective of this research was to compare the adsorption and Fenton-adsorption treatments for the removal of contaminants in leachate from landfills and thus determine the most efficient one. The adsorption process with granular activated carbon was tested in two types of samples: raw leachate and leachate treated by Fenton. The results showed color, chemical oxygen demand (COD), total nitrogen and total organic carbon (TOC) removal rates higher than 99% through the Fenton-adsorption proc...

Method for thermal swing adsorption and thermally-enhanced pressure swing adsorption

Science.gov (United States)

Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

2003-10-07

The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

Apparatus for thermal swing adsorption and thermally-enhanced pressure swing adsorption

Science.gov (United States)

Wegeng, Robert S.; Rassat, Scot D.; Stenkamp, Victoria S.; TeGrotenhuis, Ward E.; Matson, Dean W.; Drost, M. Kevin; Viswanathan, Vilayanur V.

2005-12-13

The present invention provides compact adsorption systems that are capable of rapid temperature swings and rapid cycling. Novel methods of thermal swing adsorption and thermally-enhanced pressure swing adsorption are also described. In some aspects of the invention, a gas is passed through the adsorbent thus allowing heat exchangers to be very close to all portions of the adsorbent and utilize less space. In another aspect, the adsorption media is selectively heated, thus reducing energy costs. Methods and systems for gas adsorption/desorption having improved energy efficiency with capability of short cycle times are also described. Advantages of the invention include the ability to use (typically) 30-100 times less adsorbent compared to conventional systems.

Molecular structure-adsorption study on current textile dyes.

Science.gov (United States)

Örücü, E; Tugcu, G; Saçan, M T

2014-01-01

This study was performed to investigate the adsorption of a diverse set of textile dyes onto granulated activated carbon (GAC). The adsorption experiments were carried out in a batch system. The Langmuir and Freundlich isotherm models were applied to experimental data and the isotherm constants were calculated for 33 anthraquinone and azo dyes. The adsorption equilibrium data fitted more adequately to the Langmuir isotherm model than the Freundlich isotherm model. Added to a qualitative analysis of experimental results, multiple linear regression (MLR), support vector regression (SVR) and back propagation neural network (BPNN) methods were used to develop quantitative structure-property relationship (QSPR) models with the novel adsorption data. The data were divided randomly into training and test sets. The predictive ability of all models was evaluated using the test set. Descriptors were selected with a genetic algorithm (GA) using QSARINS software. Results related to QSPR models on the adsorption capacity of GAC showed that molecular structure of dyes was represented by ionization potential based on two-dimensional topological distances, chromophoric features and a property filter index. Comparison of the performance of the models demonstrated the superiority of the BPNN over GA-MLR and SVR models.

Radioactive nuclide adsorption

International Nuclear Information System (INIS)

Fukushima, Kimichika.

1982-01-01

Purpose: To improve the efficiency of a radioactive nuclide adsorption device by applying a nickel plating on a nickel plate to render the surface active. Constitution: A capturing device for radioactive nuclide such as manganese 54, cobalt 60, 58 and the like is disposed to the inside of a pipeway provided on the upper portion of fuel assemblies through which liquid sodium as the coolant for LMFBR type reactor is passed. The device comprises a cylindrical adsorption body and spacers. The adsorption body is made of nickel and applied with a nickel plating on the surface thereof. The surface of the adsorption body is unevened to result in disturbance in the coolant and thereby improve the adsorptive efficiency. (Kawakami, Y.)

Adsorption affinity and selectivity of 3-ureidopropyltriethoxysilane grafted oil palm empty fruit bunches towards mercury ions.

Science.gov (United States)

Kunjirama, Magendran; Saman, Norasikin; Johari, Khairiraihanna; Song, Shiow-Tien; Kong, Helen; Cheu, Siew-Chin; Lye, Jimmy Wei Ping; Mat, Hanapi

2017-06-01

This study was conducted to investigate the potential application of oil palm empty fruit branches (OPEFB) as adsorbents to remove organic methylmercurry, MeHg(II), and inorganic Hg(II) from aqueous solution. The OPEFB was functionalized with amine containing ligand namely 3-ureidopropyltriethoxysilane (UPTES) aiming for better adsorption performance towards both mercury ions. The adsorption was found to be dependent on initial pH, initial concentraton, temperatures, and contact time. The maximum adsorption capacities (Q m.exp ) of Hg(II) adsorption onto OPEFB and UPTES-OPEFB were 0.226 and 0.773 mmol/g, respectively. The Q m.exp of MeHg(II) onto OPEFB, however, was higher than UPTES-OPEFB. The adsorption kinetic data obeyed the Elovich model and the adsorption was controlled by the film-diffusion step. The calculated thermodynamic parameters indicate an endothermic adsorption process. Adsorption data analysis indicates that the adsorption mechanism may include ion-exchange, complexation, and physisorption interactions. The potential applications of adsorbents were demonstrated using oilfield produced water and natural gas condensate. The UPTES-OPEFB offered higher selectivity towards both mercury ions than OPEFB. The regenerability studies indicated that the adsorbent could be reused for multiple cycles.

Synthesis and adsorption performance of Mg(OH)2 hexagonal nanosheet–graphene oxide composites

International Nuclear Information System (INIS)

Liu, Mengdi; Xu, Jing; Cheng, Bei; Ho, Wingkei; Yu, Jiaguo

2015-01-01

Graphical abstract: - Highlights: • Mg(OH) 2 hexagonal nanosheets with various mass of GO were prepared. • Mg(OH) 2 –GO composite showed enhanced adsorption capacity to congo red. • Zeta potential was used to explain preparation and adsorption mechanism. - Abstract: A series of Mg(OH) 2 hexagonal nanosheet–graphene oxide (GO) composites were synthesized through a simple hydrothermal method using magnesium nitrate and GO as precursors, sodium nitrate and sodium oxalate as additives, and sodium hydroxide and ammonia as precipitants. The as-prepared samples were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherms, Raman spectroscopy, zeta potential analysis, and scanning electron microscopy (SEM). The adsorption affinity of the as-prepared samples toward congo red (CR) in water was analyzed and investigated. Results indicated that GO addition influenced the thickness, morphology, and adsorption performance of Mg(OH) 2 hexagonal nanosheets. As GO concentration increased, the thickness decreased. Especially at high GO concentration (1 wt%), Mg(OH) 2 hexagonal nanosheets changed into aggregated flower-like spheres. Addition of small amounts of GO also increased the adsorption capacity of Mg(OH) 2 . The equilibrium adsorption data of CR on the composite were further investigated by Langmuir and Freundlich models, indicating that the Langmuir model was much more suitable for the experimental data. The sample prepared with 0.5 wt% GO showed the highest adsorption capacity with 118 mg g −1 . The experimental data were then fitted using pseudo-second order kinetics, suggesting that pseudo-second order kinetics could well describe the adsorption of CR on composites. Adsorption thermodynamics analysis showed that the adsorption activation energy was 29.2 kJ mol −1 , suggesting that the adsorption of CR onto the samples was physical adsorption. Adsorption between the samples and CR was mainly due to the strong electrostatic attraction

Fluorocarbon adsorption in hierarchical porous frameworks

NARCIS (Netherlands)

Motkuri, R.K.; Annapureddy, H.V.R.; Vijaykumar, M.; Schaef, H.T.; Martin, P.F.; McGrail, B.P.; Dang, L.X.; Krishna, R.; Thallapally, P.K.

2014-01-01

Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and

The removal of heavy metals from aqueous solution by adsorption on weathered coal

Energy Technology Data Exchange (ETDEWEB)

Meena, A.K.; Gupta, M.D.; Mishra, G.K.; Rajagopal, C.; Nagar, P.N. [Central Research Institute (Ayurveda), Gwalior (India)

2009-07-01

The adsorption followed first-order kinetics. The results indicate the potential application of this method for effluent treatment in industries and also provide strong evidence to support the adsorption mechanism proposed. On the basis of experimental results, it can be inferred that the adsorbent weathered coal may be useful in developing an adsorptive technology for the removal of heavy metals. 25 refs., 8 figs., 4 tabs.

The adsorption features between insecticidal crystal protein and nano-Mg(OH)2.

Science.gov (United States)

Pan, Xiaohong; Xu, Zhangyan; Zheng, Yilin; Huang, Tengzhou; Li, Lan; Chen, Zhi; Rao, Wenhua; Chen, Saili; Hong, Xianxian; Guan, Xiong

2017-12-01

Nano-Mg(OH) 2 , with low biological toxicity, is an ideal nano-carrier for insecticidal protein to improve the bioactivity. In this work, the adsorption features of insecticidal protein by nano-Mg(OH) 2 have been studied. The adsorption capacity could reach as high as 136 mg g -1 , and the adsorption isotherm had been fitted with Langmuir and Freundlich models. Moreover, the adsorption kinetics followed a pseudo-first or -second order rate model, and the adsorption was spontaneous and an exothermic process. However, high temperatures are not suitable for adsorption, which implies that the temperature would be a critical factor during the adsorption process. In addition, FT-IR confirmed that the protein was adsorbed on the nano-Mg(OH) 2 , zeta potential analysis suggested that insecticidal protein was loaded onto the nano-Mg(OH) 2 not by electrostatic adsorption but maybe by intermolecular forces, and circular dichroism spectroscopy of Cry11Aa protein before and after loading with nano-Mg(OH) 2 was changed. The study applied the adsorption information between Cry11Aa and nano-Mg(OH) 2 , which would be useful in the practical application of nano-Mg(OH) 2 as a nano-carrier.

Evaluation of potential of adsorption of U, Th, Pb, Zn and Ni by coconut fibers

International Nuclear Information System (INIS)

Monteiro, Raquel Almeida

2009-01-01

The residual biomass from agricultural activities has been evaluated as biosorbent for metals and organic composts from aqueous solutions, because of its adsorptive properties, low cost, abundance and to be a renewable resource. In this work, the efficiency of coir pith as biosorbent for the removal of U, Th, Pb, Zn e Ni ions from the aqueous solutions is presented. The coir pith is a by-product of the harvest of the coconut, a renewable natural source. The study was conducted by batch method. The influence of pH from 1 to 8, the dosage of the coir pith and the equilibrium time were studied. The adsorption of metal ions increased with the increase of pH and the dose. The Langmuir and Freundlich models were applied to describe the adsorption equilibrium isotherm. The kinetic process was studied using the pseudo-first order and pseudo-second order models. The Gibbs free energy was calculated. In the concentration range of 100 mg.L -1 - 500 mg.L -1 , the adsorption process was described better by the Langmuir equation for Pb 2+ and Zn 2+ ions and the Freundlich equation for UO 2 2 + , Th 4+ and Ni 2+ ions, and represented by the pseudo-second order model. The biosorption process for removal of metal ions from the solutions was considered spontaneous. The results were promising, showing perspectives of application of coir pith as biosorbent of U, Th, Pb, Zn and Ni ions in wastewater treatment processes. (author)

Adsorption of Monobutyl Phthalate from Aqueous Phase onto Two Macroporous Anion-Exchange Resins

Directory of Open Access Journals (Sweden)

Zhengwen Xu

2014-01-01

Full Text Available As new emerging pollutants, phthalic acid monoesters (PAMs pose potential ecological and human health risks. In the present study, adsorption performance of monobutyl phthalate (MBP onto two macroporous base anion-exchange resins (D-201 and D-301 was discussed. It was found that the adsorption isotherms were best fitted by the Langmuir equation while the adsorption kinetics were well described by pseudo-first-order model. Analyses of sorption isotherms and thermodynamics proved that the adsorption mechanisms for DBP onto D-201 were ion exchange. However, the obtained enthalpy values indicate that the sorption process of MBP onto D-301 is physical adsorption. The equilibrium adsorption capacities and adsorption rates of DBP on two different resins increased with the increasing temperature of the solution. D-301 exhibited a higher adsorption capacity of MBP than D-201. These results proved that D-301, as an effective sorbent, can be used to remove phthalic acid monoesters from aqueous solution.

Modeling adsorption: Investigating adsorbate and adsorbent properties

Science.gov (United States)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

Evaluation of ferrolysis in arsenate adsorption on the paddy soil derived from an Oxisol.

Science.gov (United States)

Jiang, Jun; Dai, Zhaoxia; Sun, Rui; Zhao, Zhenjie; Dong, Ying; Hong, Zhineng; Xu, Renkou

2017-07-01

Iron oxides are dominant effective adsorbents for arsenate in iron oxide-rich variable charge soils. Oxisol-derived paddy soils undergo intensive ferrolysis, which results in high leaching and transformation of iron oxides. However, little information is available concerning the effect of ferrolysis on arsenate adsorption by paddy soil and parent Oxisol. In the present study, we examined the arsenate affinity of soils using arsenate adsorption/desorption isotherms, zeta potential, adsorption kinetics, pH effect and phosphate competition experiments. Results showed that ferrolysis in an alternating flooding-drying Oxisol-derived paddy soil resulted in a significant decrease of free iron oxides and increase of amorphous iron oxides in the surface and subsurface layers. There were more reactive sites exposed on amorphous than on crystalline iron oxides. Therefore, disproportionate ratios of arsenate adsorption capacities and contents of free iron oxides were observed in the studied Oxisols compared with paddy soils. The Gibbs free energy values corroborated that both electrostatic and non-electrostatic adsorption mechanisms contributed to the arsenate adsorption by bulk soils, and the kinetic adsorption data further suggested that the rate-limiting step was chemisorption. The zeta potential of soil colloids decreased after arsenate was adsorbed on the surfaces, forming inner-sphere complexes and thus transferring their negative charges to the soil particle surfaces. The adsorption/desorption isotherms showed that non-electrostatic adsorption was the main mechanism responsible for arsenate binding to the Oxisol and derived paddy soils, representing 91.42-94.65% of the adsorption capacities. Further studies revealed that arsenate adsorption was greatly inhibited by increasing suspension pH and incorporation of phosphate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption of Cathepsin B-sensitive peptide conjugated DOX on nanodiamonds

Energy Technology Data Exchange (ETDEWEB)

Huang Shanshan; Shao Jianqun [School of Chemical Biology and Pharmaceutical Sciences, Capital Medical University, Beijing 100069 (China); Gao Lifang [Center for Food and Drug Safety Evaluation of Capital Medical University, Beijing 100069 (China); Qi Yingzhe [School of Chemical Biology and Pharmaceutical Sciences, Capital Medical University, Beijing 100069 (China); Ye Ling, E-mail: lingye@ccmu.edu.cn [School of Chemical Biology and Pharmaceutical Sciences, Capital Medical University, Beijing 100069 (China)

2011-08-01

Drug delivery mediated by nanodiamonds (NDs) has shown great promise in controlled drug release field. In present study, dipeptide (Phe-Lys) conjugated antitumor drug doxorubicin hydrochloride (DOX) with self-immolative p-aminobenzylcarbonyl (PABC) spacer was non-covalently bound to carboxylated NDs via the electrostatic interactions. HIV-1 trans-activating transcriptor peptide (TAT) was additionally integrated to this ND-based delivery system in order to enhance the transmembrane efficiency. Fourier transforms infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and zeta potentials were applied to characterize the DOX and TAT loaded ND delivery platform. The adsorption equilibrium, kinetics and thermodynamics for the adsorption of peptide conjugated DOX onto NDs were investigated. It was found that the adsorption fitted well with the Freundlich model and conformed to pseudo-second order kinetics. It also showed that the adsorption was a spontaneous and exothermic process. Therefore, our work offered a facile way to formulate a ND-based drug delivery platform with multifunctionality in a layer by layer adsorption fashion.

Adsorption of gold (III) from aqueous solutions on bagasse ash

International Nuclear Information System (INIS)

Hussain, G.; Khan, M.A.

2011-01-01

To assess the potential of cheap biomass materials for the recovery of gold from industrial, and electroplating waste water effluents, adsorption of gold (III) from dilute solutions of hydrochloric acid on bagasse ash has been studied under various experimental conditions by using batch technique. Percentage extraction of gold (III) on bagasse ash was determined from its distribution coefficients as a function of contact time, pH, adsorbent, adsorbate concentrations, and temperature. The uptake of gold (III) by bagasse ash is time, pH, metal concentration, amount of adsorbate, and temperature dependent. Adsorption data have been interpreted in terms of Langmuir, and the Freundlich equations. Thermodynamic parameters for the adsorption of gold (III) on bagasse ash have been determined at three different temperatures. The positive value of heat of adsorption; delta H 44.52 kJ/mol shows that the adsorption of gold (III) on bagasse ash is endothermic where as the negative value of delta G = -0.5303 kJ/mol at 318 K shows the spontaneity of the process. Delta G becomes more negative with increase in temperature which shows that the adsorption is more favorable at higher temperatures. Under the optimal adsorption conditions the adsorption capacity of gold is 0.70 mg /g of the adsorbent out of which 0.65 mg of gold gets desorbed with 0.1 % thiourea solution. (author)

[Characteristic of ammonia nitrogen adsorption on karst underground river sediments].

Science.gov (United States)

Guo, Fang; Chen, Kun-Kun; Jiang, Guang-Hui

2011-02-01

Karst aquifers are one of the most important aquifers in Southwestern China. One of the characteristics of karst aquifers is the enhanced permeability permits high flow velocities are capable of transporting suspended and bedload sediments. Mobile sediment in karst may act as a vector for the transport of contaminates. 14 sediment samples were collected from two underground rivers in two typical karst areas in Liuzhou city, Guangxi Autonomous Region, China. According to simulated experiment methods, characteristic of adsorption of ammonia nitrogen on sediment was studied. The results of ammonia nitrogen adsorption dynamics on sediments showed that the maximum adsorption velocity was less than 2 h. The adsorption balance quantity in 5 h accounted for 71% - 98% of the maximum adsorption quantity. The maximum adsorption quantity of ammonia nitrogen was 385.5 mg/kg, which was sediment from a cave in the middle areas of Guancun underground river system. The study of isotherm adsorption indicated adsorption quantity of NH4+ increase followed by incremental balance concentration of NH4+ in the aquatic phase. Adsorption quantity of ammonia nitrogen in sediments has a relative linear relationship with adsorption balance concentrations. Adsorption-desorption balance concentrations were all low, indicating sediments from underground rivers have great adsorption potential. Under the condition of low and high concentrations of ammonia nitrogen in overlying water, Langmuir and Tempkin couldn't simulate or simulate results couldn't reach remarkable level, whilst Linear and Freundlich models could simulate well. Research on different type sediments, sampling times and depths from two underground rivers shows characteristic of ammonia nitrogen adsorption on karst underground river sediments doesn't have good correspondence with the type of sediments. One of the reasons is there is no big difference between sediments in the development of climate, geology, hydrological conditions

Gyroidal nanoporous carbons - Adsorption and separation properties explored using computer simulations

Directory of Open Access Journals (Sweden)

S. Furmaniak

2016-02-01

Full Text Available Adsorption and separation properties of gyroidal nanoporous carbons (GNCs - a new class of exotic nanocarbon materials are studied for the first time using hyper parallel tempering Monte Carlo Simulation technique. Porous structure of GNC models is evaluated by the method proposed by Bhattacharya and Gubbins. All the studied structures are strictly microporous. Next, mechanisms of Ar adsorption are described basing on the analysis of adsorption isotherms, enthalpy plots, the values of Henry’s constants, α_{s} and adsorption potential distribution plots. It is concluded that below pore diameters ca. 0.8 nm, primary micropore filling process dominates. For structures possessing larger micropores, primary and secondary micropore filling mechanism is observed. Finally, the separation properties of GNC toward CO_{2}/CH_{4}, CO_{2}/N_{2}, and CH_{4}/N_{2} mixtures are discussed and compared with separation properties of Virtual Porous Carbon models. GNCs may be considered as potential adsorbents for gas mixture separation, having separation efficiency similar or even higher than activated carbons with similar diameters of pores.

Adsorption characteristics of water vapor on ferroaluminophosphate for desalination cycle

KAUST Repository

Kim, Youngdeuk

2014-07-01

The adsorption characteristics of microporous ferroaluminophosphate adsorbent (FAM-Z01, Mitsubishi Plastics) are evaluated for possible application in adsorption desalination and cooling (AD) cycles. A particular interest is its water vapor uptake behavior at assorted adsorption temperatures and pressures whilst comparing them to the commercial silica gels of AD plants. The surface characteristics are first carried out using N2 gas adsorption followed by the water vapor uptake analysis for temperature ranging from 20°C to 80°C. We propose a hybrid isotherm model, composing of the Henry and the Sips isotherms, which can be integrated to satisfactorily fit the experimental data of water adsorption on the FAM-Z01. The hybrid model is selected to fit the unusual isotherm shapes, that is, a low adsorption in the initial section and followed by a rapid vapor uptake leading to a likely micropore volume filling by hydrogen bonding and cooperative interaction in micropores. It is shown that the equilibrium adsorption capacity of FAM-Z01 can be up to 5 folds higher than that of conventional silica gels. Owing to the quantum increase in the adsorbate uptake, the FAM-Z01 has the potential to significantly reduce the footprint of an existing AD plant for the same output capacity. © 2014 Elsevier B.V.

Evaluation of the potential cationic dye removal using adsorption by graphene and carbon nanotubes as adsorbents surfaces

Directory of Open Access Journals (Sweden)

Akbar Elsagh

2017-05-01

Full Text Available We are employed in the present study of single-walled carbon nanotubes (SWCNTs, carboxylate group functionalized single-walled carbon nanotubes (SWCNT-COOH, graphene (G and graphene oxide (GO as alternative adsorbents for the removal of cationic dye Basic Red 46 (BR 46, from aqueous solution. Various physico-chemical parameters were studied such as electrical conductivity behaviors, contact time, solution pH, and dye concentration. The experimental results show that SWCNTs, SWCNT-COOH, G and GO are promising adsorbents for removing BR 46. The adsorption equilibrium data were analyzed using various adsorption isotherms, and the results have shown that adsorption behavior of BR 46 could be described reasonably well by the Langmuir isotherm. Results showed that the removal of BR 46 increased with increasing initial dye concentration, contact time and pH. Adsorption kinetics data were modeled using the pseudo-first and pseudo-second order, and intra-particle diffusion models. Results show that the pseudo-first order kinetic model for SWCNTs, SWCNT-COOH and the pseudo-second order for G and GO were found to correlate the experimental data well.

Integration of coagulation and adsorption for removal of N-nitrosodimethylamine (NDMA) precursors from biologically treated municipal wastewater.

Science.gov (United States)

Wang, Miaomiao; Meng, Yingjie; Ma, Defang; Wang, Yan; Li, Fengli; Xu, Xing; Xia, Chufan; Gao, Baoyu

2017-05-01

This study investigated the N-nitrosodimethylamine (NDMA) formation potential of various dissolved organic matter (DOM) fractions in biologically treated municipal wastewater by UF fractionation, XAD-8 resin adsorption isolation, and excitation and emission matrix (EEM) fluorescence spectroscopy. Removal of various NDMA precursor fractions was also analyzed to evaluate the efficiency of traditional water treatment processes (coagulation, adsorption, and coagulation-adsorption). Results showed that NDMA were mainly formed by low molecular weight (MW) fractions (NDMA formation potential (57%), followed by isolated adsorption treatment (50%) and isolated coagulation treatment (28%). The powdered activated carbon (PAC) adsorption process could reduce the high MW precursors (>30 kDa) by 48%, which was higher than other treatments. In contrast, the highest uptake (66%) of low MW precursors (<30 kDa) was achieved by the coagulation-adsorption process. All treatments preferentially removed the hydrophobic acids (HoA) fraction compared to other fractions. Coagulation could remove more fulvic acid-like substances and adsorption could remove more microbial by-products and aromatic proteins.

Adsorption mechanism of microcrystalline cellulose as green adsorbent for the removal of cationic methylene blue dye

International Nuclear Information System (INIS)

Tan, K.B.; Salamatinia, B.

2016-01-01

The adsorption mechanism of pure cellulose is yet to be explored. Thus, in this study, the adsorption mechanism of Microcrystalline Cellulose (MCC), a polysaccharide which is renewable, low cost and non-toxic, was studied on the adsorption of model dye Methylene blue (MB). It was found that the main adsorption mechanism of MB on MCC was due to the electrostatic attraction between the positively charged MB dye and negatively charged MCC. Thus, physical adsorption was the dominant effect, since electrostatic attraction is categorized as physical adsorption. This was verified by Dubinin-Radushkevich isotherm, whereby mean free energy adsorption value was found to be less than 8 kJ/mol. The values of Gibbs free energy for thermodynamics studies were found to be within the range of -20 kJ/mol and 0 kJ/mol, which also indicated physical adsorption. It was due to the electrostatic attraction as adsorption mechanism of this adsorption process which resulted rapid adsorption of MB dye. It was found that equilibrium dye concentration was achieved between 1-3 minutes, depending on the adsorption temperature. The rapid adsorption, as compared to a lot of materials, showed the potential of MCC as the future of green adsorbent. The adsorption of Methylene Blue on MCC fitted well in Langmuir Isotherm, with R2 values of higher than 0.99, while fitted moderately in Freundlich Isotherm, with R2 values between 0.9224 and 0.9223. Comparatively, the adsorption of MB on MCC fitted best Langmuir Isotherm as compared to Freundlich Isotherm which monolayer adsorption occurred at the homogenous surface of MCC. This also indicated adsorbed MB molecules do not interact with each other at neighboring adsorption sites. The maximum adsorption capacity calculated from Langmuir Isotherm was found to be 4.95 mg/g. Despite the potential of MCC as green adsorbent, the challenge of low adsorption capacity has to be addressed in the future. (author)

Effects of buffer agents on hydrogen adsorption and desorption at/within activated carbon for the negative electrode of aqueous asymmetric supercapacitors

International Nuclear Information System (INIS)

Chien, Hsiu-Chuan; Wu, Tzu-Ho; Rajkumar, Muniyandi; Hu, Chi-Chang

2016-01-01

Highlights: • H adsorption causes local pH increase and negatively shifts the double-layer potential window. • The local pH variation at AC/electrolyte interface can be controlled via adding buffer agents. • H adsorption potential on AC in buffer electrolytes follows the Nernstian dependence. • The pseudocapacitive reversibility of H adsorption/desorption at/within AC is too poor. - Abstract: In this work, the effects of adding buffer agents into aqueous electrolytes on the hydrogen adsorption/desorption behaviour at/within activated carbon are systematically investigated for the negative electrode of asymmetric supercapacitors. Due to the poor electrochemical reversibility of hydrogen adsorption/desorption at/within activated carbon, the hydrogen responses at/within activated carbon are not suitable for pseudo-capacitive energy storage of high-performance asymmetric supercapacitor. The electrochemical adsorption of H atoms consumes protons and causes the local pH change at the activated carbon/electrolyte interface, leading to the negative shift in the H adsorption potential when weakly acidic, neutral, and weakly basic electrolytes without buffer agents are employed. The addition of buffer agents into electrolytes significantly improves the rate of proton supply and promotes the rate of hydrogen adsorption at/within AC. Interestingly, the onset potential of significant H adsorption obtained from the buffered electrolytes generally follows the Nernstian dependence, suggesting the Nerstian dependence of H"+/H_a_d_s on AC at all pH values. In order to obtain the energy storage devices with high coulombic and energy efficiencies, the onset potential of significant H adsorption obtained from the electrolyte containing buffer agents is a reliable lower potential limit of the AC-coated negative electrode for aqueous asymmetric supercapacitors.

Surface and adsorptive properties of Moringa oleifera bark for removal of V(V) from aqueous solutions.

Science.gov (United States)

Mnisi, Robert Londi; Ndibewu, Peter Papoh

2017-11-04

The bark of Moringa oleifera, a cheap and readily available natural biopolymeric resource material, found to significantly reduce coliform load and turbidity in contaminated water is investigated in this paper. Its surface and adsorptive properties are investigated to explore its adsorptive potential in removing V(V) from aqueous solutions. Surface properties were investigated using FTIR, HRSEM/EDS, IC, and BET-N 2 adsorption techniques. Adsorptive properties were investigated by optimizing adsorption parameters such as pH, temperature, initial metal concentration, and adsorbent dosage, using V(V) as an adsorbate. The adsorption-desorption isotherms are typical of type II with a H3 hysteresis loop and is characteristic of a largely macroporous material. Bottle ink pores are observed, which can provide good accessibility of the active sites, even though the internal BET surface area is typically low (1.79 g/m 2 ). Solution pH significantly influences the adsorptive potential of the material. The low surface area negatively impacts on the adsorption capacity, but is compensated for by the exchangeable anions (Cl - , F - , PO 4 3- , NO 3 - , and SO 4 2- ) and cations (Ca 2+ , K + , Mg 2+ , and Al 3+ ) at the surface and the accessibility of the active sites. Adsorption isotherm modeling show that the surface is largely heterogeneous with complex multiple sites and adsorption is not limited to monolayer.

Adsorption behavior of modified Iron stick yam skin with Polyethyleneimine as a potential biosorbent for the removal of anionic dyes in single and ternary systems at low temperature.

Science.gov (United States)

Zhang, Yan-Zhuo; Li, Jun; Zhao, Jing; Bian, Wei; Li, Yun; Wang, Xiu-Jie

2016-12-01

The skin of Iron stick yam (ISY) was modified with Polyethyleneimine (ISY@PEI) and evaluated for use as a potential biosorbent to remove the anionic dyes Sunset yellow (SY), Lemon yellow (LY), and Carmine (CM) from wastewater under low temperature conditions (5-15°C) in single and ternary dye systems. Both in the single and ternary systems, experimental data showed that adsorption capacity reached the highest value at 5°C, and adsorption capacity decreased when the temperature increased (10-50°C). The equilibrium data fitted very well to the Langmuir model and the extended Langmuir isotherm, for the single and ternary systems, respectively. The maximum adsorption capability was 138.92, 476.31, and 500.13mg/g for LY, SY, and CM, respectively, in a single system and 36.63, 303.31, and 294.12mg/g for LY, SY, and CM, respectively, in a ternary system. The adsorption followed pseudo-second-order kinetics. The thermodynamic parameters indicated that it was a spontaneous and exothermic process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Waved graphene: Unique structure for the adsorption of small molecules

International Nuclear Information System (INIS)

Pan, Hui

2017-01-01

We propose waved graphenes for the strong adsorption of molecules and investigate their potential applications. We find that the physical adsorption of molecules on waved graphene is greatly enhanced by compression. At optimal compression, the physical adsorption energies of H_2, N_2, NO, and CO are increased by 6–9 times, and that for O_2 is more than 2 times. We show that the energy for their chemical adsorption on waved graphene decreases dramatically with the increment of compression. The energy of dissociation of H_2 on flat graphene is 1.63 eV and reduced to 0.06 eV (96% reduction) on waved graphene at a compression of 50%, respectively. The energy for chemical adsorption of O_2 on waved graphenes is extremely reduced from 0.98 eV to −0.57 eV as with compression increasing from 0 to 50%, indicating the transition of endothermic chemical adsorption to exothermic. We further show that the electronic properties of waved graphenes are modified, leading to the change of electrical characters. We see that the waved graphenes may find applications in gas storage, sensor and catalyst because of enhanced physical and chemical adsorption and the induced change of electronic properties. - Highlights: • Adsorption of small molecules on waved graphene is greatly enhanced. • Strong physical adsorption in the trough of waved graphene can be achieved by tuning the curvature. • Chemical adsorption is on the crest of waved graphene. • Exothermic dissociation of H2 and O2 can be realized on waved graphene under high compression. • Wave graphene can be candidates as catalysts and gas storage/sensor.

Waved graphene: Unique structure for the adsorption of small molecules

Energy Technology Data Exchange (ETDEWEB)

Pan, Hui, E-mail: huipan@umac.mo

2017-03-01

We propose waved graphenes for the strong adsorption of molecules and investigate their potential applications. We find that the physical adsorption of molecules on waved graphene is greatly enhanced by compression. At optimal compression, the physical adsorption energies of H{sub 2}, N{sub 2}, NO, and CO are increased by 6–9 times, and that for O{sub 2} is more than 2 times. We show that the energy for their chemical adsorption on waved graphene decreases dramatically with the increment of compression. The energy of dissociation of H{sub 2} on flat graphene is 1.63 eV and reduced to 0.06 eV (96% reduction) on waved graphene at a compression of 50%, respectively. The energy for chemical adsorption of O{sub 2} on waved graphenes is extremely reduced from 0.98 eV to −0.57 eV as with compression increasing from 0 to 50%, indicating the transition of endothermic chemical adsorption to exothermic. We further show that the electronic properties of waved graphenes are modified, leading to the change of electrical characters. We see that the waved graphenes may find applications in gas storage, sensor and catalyst because of enhanced physical and chemical adsorption and the induced change of electronic properties. - Highlights: • Adsorption of small molecules on waved graphene is greatly enhanced. • Strong physical adsorption in the trough of waved graphene can be achieved by tuning the curvature. • Chemical adsorption is on the crest of waved graphene. • Exothermic dissociation of H2 and O2 can be realized on waved graphene under high compression. • Wave graphene can be candidates as catalysts and gas storage/sensor.

Adsorption of asparagine on the gold electrode and air/solution interface

International Nuclear Information System (INIS)

Slojkowska, R.; Palys, B.; Jurkiewicz-Herbich, M.

2004-01-01

The adsorption of asparagine (Asn) on a gold electrode from 0.1 M LiClO 4 aqueous solutions was investigated. The experimental data obtained from ac impedance measurements were analyzed to determine the dependence of adsorption parameters, i.e. the standard Gibbs energy of adsorption (ΔG 0 ), maximal value of surface excess concentration (Γ max ) of Asn and parameter of interactions in the adsorbed layer (A) on the electrode potential. The relatively large value of Gibbs energy of adsorption (∼ -47 kJ mol -1 ) gives the evidence of a very strong adsorption of Asn at the polycrystalline Au electrode. The comparison of the adsorption behavior of Asn at the air/solution and the Au/solution interfaces points out to the significant electronic interactions of adsorbate molecules with the Au electrode, since the adsorption of Asn on a free surface (from the same solutions) is very week. The analysis of the electrochemical data as well as the infrared reflection absorption spectroscopy (IRAS) results reveal that Asn molecules are anchored to the Au surface through oxygen atoms of the carboxylate group COO - and through the amide carbonyl group

Adsorption decontamination of radioactive waste solvent by activated alumina and bauxites

International Nuclear Information System (INIS)

Hassan, N.M.; Marra, J.C.; Kyser, E.A.

1994-01-01

An adsorption process utilizing activated alumina and activated bauxite adsorbents was evaluated as a function of operating parameters for the removal of low level radioactive contaminants from organic waste solvent generated in the fuel reprocessing facilities and support operations at Savannah River Site. The waste solvent, 30% volume tributyl phosphate in n-paraffin diluent, was degraded due to hydrolysis and radiolysis reactions of tributyl phosphate and n-paraffin diluent, producing fission product binding degradation impurities. The process, which has the potential for removing these activity-binding degradation impurities from the solvent, was operated downflow through glass columns packed with activated alumina and activated bauxite adsorbents. Experimental breakthrough curves were obtained under various operating temperatures and flow rates. The results show that the adsorption capacity of the activated alumina was in the order 10 4 dpm/g and the capacity of the activated bauxite was 10 5 dpm/g. The performance of the adsorption process was evaluated in terms of dynamic parameters (i.e. adsorption capacity, the height and the efficiency of adsorption zone) in such a way as to maximize the adsorption capacity and to minimize the height of the mass transfer or adsorption zone

Adsorption of uranium on halloysite

International Nuclear Information System (INIS)

Kilislioglu, A.; Bilgin, B.

2002-01-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Adsorption of uranium on halloysite

Energy Technology Data Exchange (ETDEWEB)

Kilislioglu, A.; Bilgin, B. [Istanbul Univ. (Turkey). Faculty of Engineering

2002-07-01

Adsorption of uranium (U(VI)) from aqueous solutions on halloysite type clay was studied as a function of amount of adsorbent, initial concentration and pH. The values of adsorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The mean energy of adsorption was calculated as 5.91 kJ/mol from D-R adsorption isotherm. Lagergren and Bangham equation has been used for dynamic modelling of process and the rate constants of adsorption of uranium on halloysite type clay were calculated at 293, 313 and 333 K. In order to explain the mechanism of adsorption reaction, the rate constants were calculated at high and low uranium concentrations. Adsorption reaction was studied at 293, 303, 313, 323 and 333 K for halloysite type clay and also thermodynamic constants have been calculated. The results show that the adsorption reaction was endothermic and more spontaneous at high temperature. (orig.)

Adsorption of human fibrinogen and albumin onto hydrophobic and hydrophilic Ti6Al4V powder

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Sánchez, Jesús; Gallardo-Moreno, Amparo M.; Bruque, José M.; González-Martín, M. Luisa, E-mail: mlglez@unex.es

2016-07-15

Adsorption of proteins on solid surfaces has been widely studied because of its importance in various biotechnological, medical and technical applications, such as medical implants or biosensors. One of the main problems is the adsorption-induced conformational changes because they often modify the biological activity of the proteins, which is believed to be a key factor on the subsequent cellular adhesion. The aim of this work is the study of the adsorption of human fibrinogen (Fg) and human serum albumin (HSA) onto Ti6Al4V particles, commercially available on different size, that are used to elaborate scaffolds to provide structural support to cell proliferation, promoting tissue development and bone regeneration among others. The study was done through the analysis of the adsorption isotherms and the electrical characterization of surfaces after adsorption in terms of the zeta potential (ζ). From this analysis it seems that Fg adsorbs preferentially vertically oriented (end-on) and HSA moves sequentially over the surface of the Ti6Al4V particles through dimmer formation, allowing adsorption progress over this initial bilayer. The zeta potential values of both proteins remain constant when the monolayer is formed. The study also extends the analysis of both adsorption behaviour and ζ potential characterization factors to the influence of the substrate hydrophobicity as this property can be modified for the Ti6Al4V by irradiating it with ultraviolet light (UV-C) without changes on its chemical composition [1,2]. Differences at low protein concentrations were found for both isotherms and zeta-potential values.

Modeling of Shale Gas Adsorption and its Influence on Phase Equilibrium

DEFF Research Database (Denmark)

Sandoval Lemus, Diego Rolando; Yan, Wei; Michelsen, Michael Locht

2018-01-01

provides a comparison of several engineering models for gas adsorption in shale based on the recent literature data for pure and binary gases. For pure components, Langmuir, the modied Toth-Langmuir, and the Multicomponent Potential Theory of Adsorption using Dubinin-Radushkevich potential (MPTA-DRA) were...... compared. The three models show similar deviations lower than 10%. For binary gases, Multicomponent Langmuir (ML), Ideal Adsorbed Solution Theory (IAST) and MPTA were evaluated, where MPTA shows the lowest deviation with 17.9%. Additionally, we presented an analysis of the phase envelope shift under...

Synthesis and adsorption performance of Mg(OH){sub 2} hexagonal nanosheet–graphene oxide composites

Energy Technology Data Exchange (ETDEWEB)

Liu, Mengdi; Xu, Jing; Cheng, Bei [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Tai Po, N.T. Hong Kong (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2015-03-30

Graphical abstract: - Highlights: • Mg(OH){sub 2} hexagonal nanosheets with various mass of GO were prepared. • Mg(OH){sub 2}–GO composite showed enhanced adsorption capacity to congo red. • Zeta potential was used to explain preparation and adsorption mechanism. - Abstract: A series of Mg(OH){sub 2} hexagonal nanosheet–graphene oxide (GO) composites were synthesized through a simple hydrothermal method using magnesium nitrate and GO as precursors, sodium nitrate and sodium oxalate as additives, and sodium hydroxide and ammonia as precipitants. The as-prepared samples were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherms, Raman spectroscopy, zeta potential analysis, and scanning electron microscopy (SEM). The adsorption affinity of the as-prepared samples toward congo red (CR) in water was analyzed and investigated. Results indicated that GO addition influenced the thickness, morphology, and adsorption performance of Mg(OH){sub 2} hexagonal nanosheets. As GO concentration increased, the thickness decreased. Especially at high GO concentration (1 wt%), Mg(OH){sub 2} hexagonal nanosheets changed into aggregated flower-like spheres. Addition of small amounts of GO also increased the adsorption capacity of Mg(OH){sub 2}. The equilibrium adsorption data of CR on the composite were further investigated by Langmuir and Freundlich models, indicating that the Langmuir model was much more suitable for the experimental data. The sample prepared with 0.5 wt% GO showed the highest adsorption capacity with 118 mg g{sup −1}. The experimental data were then fitted using pseudo-second order kinetics, suggesting that pseudo-second order kinetics could well describe the adsorption of CR on composites. Adsorption thermodynamics analysis showed that the adsorption activation energy was 29.2 kJ mol{sup −1}, suggesting that the adsorption of CR onto the samples was physical adsorption. Adsorption between the samples and CR was mainly due to the

Adsorption of Nanoplastics on Algal Photosynthesis

Science.gov (United States)

Turner, James; Bhattacharya, Priyanka; Lin, Sijie; Ke, Pu Chun

2010-03-01

The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, has become a global concern in recent years. Photo, chemical and physical degradations constantly fragment these plastics into a wide array of macroscopic to microscopic particles. As a result, marine organisms such as algae may be exposed to plastic particles through ingestion, adsorption and other forms of uptake. Such interactions, currently little understood, could potentially impact on the health state of the entire food chain. Here we report on polystyrene-algae interaction and its impact on algal photosynthesis. We first investigated the adsorption of polystyrene beads (20 nm) on a cellulose film coated on a 96-well plate. We derived a supralinear increase of the adsorption with the beads concentration for both positively and negatively charged polystyrene beads, with a saturation observed for the negatively charged polystyrene beads of concentration above 1.6 mg/mL. Using a bicarbonate indicator we discovered decreased carbon dioxide depletion due to polystyrene-algae binding. Since polystyrene beads also mediated algae aggregation, nanoplastics may alternatively be harnessed for waste water treatment.

Use of activated carbon adsorption in conjunction with radiation treatment processes

International Nuclear Information System (INIS)

Dickson, L.W.; Lopata, V.J.; Toft-Hall, A.; Kremers, W.; Singh, A.

1988-01-01

This report presents the results of an assessment of the potential applications of combined adsorption-irradiation treatment processes. The rationale for the study was to determine whether the cost of radiation treatment could be reduced by concentrating target species on an adsorbent in the radiation field. Several different studies on adsorption-irradiation treatment were identified in the literature, and experimental work was done on both the conversion of sulphur dioxide to elemental sulphur, and the removal of trihalomethanes from water by adsorption on activated carbon and subsequent irradiation. Adsorption-irradiation treatment would appear to be less costly than irradiation alone for radiolytic decomposition of target species at low concentration in liquid streams, in the presence of high-surface-area, electrically insulating adsorbents. 116 refs

Adsorption of diastase over natural halloysite nanotubes (HNTs)

Science.gov (United States)

Twaiq, F.; Chang, K. X.; Ling, J. Y. W.

2017-06-01

Adsorption of diastase over natural halloysite nanotubes is studied in order to evaluate the adsorption capacity of diastase. The halloysite surface characteristics were assessed using nitrogen adsorption, x-ray diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier transformed infrared (FTIR). The surface area of the natural halloysite is found to be 51 m2·g-1, with total pore volume of 0.106 cm3·g-1. The natural halloysite has a basal spacing (d001) of 10 Å confirming the structure of the natural halloysite material. TGA results indicated that halloysite loses its interlayer water in the range of 30 to 105 °C and the dehydration in the structural layer above 150 °C. The dehydroxylation of halloysite has occurred at approximately 460 °C. The FTIR result of the thermally treated halloysite sample indicated that the bands observed are assigned to Si-O and Al-O bonds. The effects of solution pH and temperature were studied on the adsorption capacity and percent removal of diastase from the solution. The adsorption kinetic found to fit well with both the Pseudo first-order and Pseudo second-order models, and the values of the kinetic constant were found to be 0.173 min-1 and 0.00018 g·mg-1·min-1 respectively. The Langmuir isotherm model is found to fit well to the adsorption data and a kinetic value is found to be 0.00059 m3·g-1. The maximum adsorption capacity was found to be 370 mg·g-1, indicating the potential for applications of the natural nanostructured halloysite material as an effective adsorbent for diastase.

Leaching potential of chlorpyrifos in an Andisol and Entisol: adsorption-desorption and degradation studies

Science.gov (United States)

Mosquera-Vivas, Carmen; Walther Hansen, Eddy; Garcia-Santos, Glenda; Obregón-Neira, Nelson; Celis-Ossa, Raul Ernesto; González-Murillo, Carlos Alberto; Juraske, Ronnie; Hellweg, Stefanie; Guerrero-Dallos, Jairo Arturo

2017-04-01

Ecological status of tropical soils like high OC content and microbial activity plays a key role to reduce the leaching of insecticide chlorpyrifos through the soil profile and therefore into groundwater. We found that chlorpyrifos has "transitional" leaching potential (GUS values varied between 1.8 and 2.5) throughout the soil depth, which differs from the "nonleacher" classification for temperate soils as based on surface level t1/2 and Koc values from international databases. These findings provide strong evidence of the importance of estimating the transport parameters and insecticide concentrations in different soil layers, especially when the amount and type of OC content vary throughout the soil profile. We got to such conclusions after studying the soil profile structural composition of soil organic matter and the adsorption/desorption characteristics of the insecticide in two different soil profiles (Andisol and Entisol) under agriculture production using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and batch analysis methods.

Advanced adsorption cooling cum desalination cycle: A thermodynamic framework

KAUST Repository

Chakraborty, Anutosh

2011-01-01

We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property surfaces of adsorbent-adsorbate system and the adsorption interaction potential between them. Employing the proposed formulations, the coefficient of performance (COP) and overall performance ratio (OPR) of adsorption cycle are computed for various pore widths of solid adsorbents. These results are compared with experimental data for verifying the proposed thermodynamic formulations. It is found from the present analysis that the COP and OPR of adsorption cooling cum desalination cycle is influenced by (i) the physical characteristics of adsorbents, (ii) characteristics energy and (iii) the surface-structural heterogeneity factor of adsorbent-water system. The present study confirms that there exists a special type of adsorbents having optimal physical characteristics that allows us to obtain the best performance.

Adsorption study of copper (II) by chemically modified orange peel

International Nuclear Information System (INIS)

Feng Ningchuan; Guo Xueyi; Liang Sha

2009-01-01

An adsorbent, the chemically modified orange peel, was prepared from hydrolysis of the grafted copolymer, which was synthesized by interaction of methyl acrylate with cross-linking orange peel. The presence of poly (acrylic acid) on the biomass surface was verified by infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetry (TG). Total negative charge in the biomass surface and the zeta potentials were determined. The modified biomass was found to present high adsorption capacity and fast adsorption rate for Cu (II). From Langmuir isotherm, the adsorption capacity for Cu (II) was 289.0 mg g -1 , which is about 6.5 times higher than that of the unmodified biomass. The kinetics for Cu (II) adsorption followed the pseudo-second-order kinetics. The adsorbent was used to remove Cu (II) from electroplating wastewater and was suitable for repeated use for more than four cycles.

An Analytical Model for Adsorption and Diffusion of Atoms/Ions on Graphene Surface

Directory of Open Access Journals (Sweden)

Yan-Zi Yu

2015-01-01

Full Text Available Theoretical investigations are made on adsorption and diffusion of atoms/ions on graphene surface based on an analytical continuous model. An atom/ion interacts with every carbon atom of graphene through a pairwise potential which can be approximated by the Lennard-Jones (L-J potential. Using the Fourier expansion of the interaction potential, the total interaction energy between the adsorption atom/ion and a monolayer graphene is derived. The energy-distance relationships in the normal and lateral directions for varied atoms/ions, including gold atom (Au, platinum atom (Pt, manganese ion (Mn2+, sodium ion (Na1+, and lithium-ion (Li1+, on monolayer graphene surface are analyzed. The equilibrium position and binding energy of the atoms/ions at three particular adsorption sites (hollow, bridge, and top are calculated, and the adsorption stability is discussed. The results show that H-site is the most stable adsorption site, which is in agreement with the results of other literatures. What is more, the periodic interaction energy and interaction forces of lithium-ion diffusing along specific paths on graphene surface are also obtained and analyzed. The minimum energy barrier for diffusion is calculated. The possible applications of present study include drug delivery system (DDS, atomic scale friction, rechargeable lithium-ion graphene battery, and energy storage in carbon materials.

Adsorption behavior of radionuclide in water containing sea salts

International Nuclear Information System (INIS)

Kani, Yuko; Kamoshida, Mamoru; Asano, Takashi; Tamata, Shin

2012-01-01

Waste water caused by the Fukushima Dai-ichi Nuclear Reactor accident contains high level radioactive material with impurities of sea water origin, such as chloride, sodium and magnesium. These impurities have the potential to inhibit the adsorption reaction of radioactive cesium and strontium to adsorbents. We have studied adsorption behavior of radioactive cesium and strontium to adsorbents to measure distribution coefficients (Kd) in the condition of different sea water concentrations. For cesium adsorption, the dependence of Kd on the sea water concentration was affected by the adsorption mechanism of adsorbent; the adsorbents which adsorbed cesium by intercalation showed less dependence of Kd on the sea water concentration, while those adsorbed cesium by ion exchange had smaller Kd with increasing the sea water concentration. For strontium adsorption, Kd decreased as the sea water concentration increased for both adsorbents which adsorbed strontium by intercalation and by ion exchange. The inhibition of intercalation and ion exchange reaction of strontium by calcium ion, that exists high concentration in sea water (400 ppm) and similar hydrated ionic radius with strontium, will cause the decrease of Kd for strontium in the sea water with higher concentration. (author)

A density functional study of nitrogen adsorption in single-wall carbon nanotubes

International Nuclear Information System (INIS)

Zhu Jie; Wang Yao; Li Wenjun; Wei Fei; Yu Yangxin

2007-01-01

An understanding of the adsorption behaviour of nitrogen in single-wall carbon nanotubes (SWCNTs) is necessary for obtaining information on its pores by nitrogen adsorption manometry. Non-local density functional theory was used to simulate nitrogen adsorption behaviour, including the adsorption isotherms, equilibrium density profiles and potential energy of the nitrogen molecules at 77 K, inside SWCNTs with diameters ranging from 0.696 to 3.001 nm. With increasing diameter, nitrogen adsorption changes from continuous filling in one dimension to a two-stage adsorption that corresponds to monolayer formation followed by multilayer condensation. The average density of the adsorbed nitrogen and the density profiles, especially in small diameter SWCNTs, were used to analyse the adsorbate phase at the saturation pressure. The results indicate that the type of pore filling depends primarily on the ratio of the SWCNT diameter to the adsorbate molecular diameter. The filling of SWCNTs is not a simple capillary condensation process, but is dominated by geometrical limitation

Adsorption of VOCs on reduced graphene oxide.

Science.gov (United States)

Yu, Lian; Wang, Long; Xu, Weicheng; Chen, Limin; Fu, Mingli; Wu, Junliang; Ye, Daiqi

2018-05-01

A modified Hummer's method was adopted for the synthesis of graphene oxide (GO) and reduced graphene oxide (rGO). It was revealed that the modified method is effective for the production of GO and rGO from graphite. Transmission electron microscopy (TEM) images of GO and rGO showed a sheet-like morphology. Because of the presence of oxygenated functional groups on the carbon surface, the interlayer spacing of the prepared GO was higher than that of rGO. The presence of OH and CO groups in the Fourier transform infrared spectra (FTIR) spectrum and G-mode and 2D-mode in Raman spectra confirmed the synthesis of GO and rGO. rGO (292.6m 2 /g) showed higher surface area than that of GO (236.4m 2 /g). The prepared rGO was used as an adsorbent for benzene and toluene (model pollutants of volatile organic compounds (VOCs)) under dynamic adsorption/desorption conditions. rGO showed higher adsorption capacity and breakthrough times than GO. The adsorption capacity of rGO for benzene and toluene was 276.4 and 304.4mg/g, respectively. Desorption experiments showed that the spent rGO can be successfully regenerated by heating at 150.0°C. Its excellent adsorption/desorption performance for benzene and toluene makes rGO a potential adsorbent for VOC adsorption. Copyright © 2017. Published by Elsevier B.V.

Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test.

Science.gov (United States)

Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

2013-10-01

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. Copyright © 2013 Elsevier Ltd. All rights reserved.

Adsorption facility and adsorption vessel for radioactive carbon dioxide

International Nuclear Information System (INIS)

Harashina, Heihachi; Miwa, Keiichi; Kobayashi, Takeo.

1992-01-01

If 14 CO 2 gas-containing gases to be adsorbed are pressurized and sent to a packaging adsorption means, CO 2 ingredient in the gases to be adsorbed is adsorbed or absorbed, and remaining gases are passed through and sent out to downstream. CO 2 adsorption or absorption of the packaging adsorption means is judged by monitoring the state of the remaining gases, and if it is normal, remaining gases are sent further to downstream and processed. If abnormality is found, a gas feedback system is operated, and CO 2 removing gas is sent again to the packaging adsorption means, in which CO 2 gases are adsorbed or absorbed again repeatingly. With such procedures, in a case where C 14 nuclides having a long half decay time are supplied in the form of 14 CO 2 gas, they are efficiently adsorbed or absorbed in the packaging system to improve removing and storing property of 14 C nuclides. (T.M.)

Screening of active metals for reactive adsorption desulfurization adsorbent using density functional theory

Energy Technology Data Exchange (ETDEWEB)

Wang, Lei; Zhao, Liang, E-mail: liangzhao@cup.edu.cn; Xu, Chunming; Wang, Yuxian; Gao, Jinsen

2017-03-31

Highlights: • Electronic characteristics determined adsorption characteristics of transition metals. • Cobalt has the similar adsorption ability of thiophene as nickel. • Adsorption capacity of Cr and Mo was extremely fierce, while Cu has the potential ability for adsorbing thiophene. • The preference adsorption site for thiophene was hollow site on all the seven surface. - Abstract: To explore characteristics of active metals for reactive adsorption desulfurization (RADS) technology, the adsorption of thiophene on M (100) (M = Cr, Mo, Co, Ni, Cu, Au, and Ag) surfaces was systematically studied by density functional theory with vdW correction (DFT + D3). We found that, in all case, the most stable molecular adsorption site was the hollow site and adsorptive capabilities of thiophene followed the order: Cr > Mo > Co ≈ Ni > Cu > Au ≈ Ag. By analyzing the nature of binding between thiophene and corresponding metals and the electronic structure of metals, the excessive activities of Cr and Mo were found to have a negative regeneration, the passive activities of Au and Ag were found to have an inactive adsorption for RADS adsorbent alone, while Ni and Co have appropriate characteristics as the active metals for RADS, followed by Cu.

Overview of the physical-chemical properties of the noble gases

International Nuclear Information System (INIS)

McKinley, C.

1973-01-01

This paper lists the concentrations of noble gases in the atmosphere and the relative abundance of the stable isotopes. Selected physical properties are tabulated; solubilities of noble gases in water and other liquids, and liquid-vapor equilibria data for binary systems containing a noble gas are presented. Adsorption data are tabulated for illustrative conventional adsorbents and are also presented by a Polanyi correlation. Clathration, biochemical effects, and chemical reactivity are highlighted. Analytical procedures are briefly described. Other relatively non-reactive gases present in the atmosphere in trace quantities are mentioned: methane, carbon tetrafluoride, and sulfur hexafluoride.

Adsorptive removal of naproxen and clofibric acid from water using metal-organic frameworks.

Science.gov (United States)

Hasan, Zubair; Jeon, Jaewoo; Jhung, Sung Hwa

2012-03-30

Adsorptive removal of naproxen and clofibric acid, two typical PPCPs (pharmaceuticals and personal care products), has been studied using metal-organic frameworks (MOFs) for the first time. The removal efficiency decreases in the order of MIL-101>MIL-100-Fe>activated carbon both in adsorption rate and adsorption capacity. The adsorption kinetics and capacity of PPCPs generally depend on the average pore size and surface area (or pore volume), respectively, of the adsorbents. The adsorption mechanism may be explained with a simple electrostatic interaction between PPCPs and the adsorbent. Finally, it can be suggested that MOFs having high porosity and large pore size can be potential adsorbents to remove harmful PPCPs in contaminated water. Copyright © 2012 Elsevier B.V. All rights reserved.

Adsorption behaviour of hydrogarnet for humic acid

Science.gov (United States)

Maeda, Hirotaka; Kurosaki, Yuichi; Nakayama, Masanobu; Ishida, Emile Hideki; Kasuga, Toshihiro

2018-04-01

Discharge of humic acid (HA) in aqueous environments is a key health and aesthetic issue. The present work investigates the use of hydrogarnet as a novel adsorbent for HA. Hydrogarnet was hydrothermally synthesized with different solvents to control the chemical composition. Hydrogarnet with three types of chemical compositions had better adsorption properties for HA than hydrogarnet with a single chemical composition. Controlling the chemical composition of hydrogarnet increased the number of hydroxyl groups and the overall binding energy of the system, leading to changes in the zeta potential. The enhancement of these adsorption properties is related to the increased numbers of hydroxyl groups on the surface and their diverse binding energies.

Modeling Adsorption-Desorption Processes at the Intermolecular Interactions Level

Science.gov (United States)

Varfolomeeva, Vera V.; Terentev, Alexey V.

2018-01-01

Modeling of the surface adsorption and desorption processes, as well as the diffusion, are of considerable interest for the physical phenomenon under study in ground tests conditions. When imitating physical processes and phenomena, it is important to choose the correct parameters to describe the adsorption of gases and the formation of films on the structural materials surface. In the present research the adsorption-desorption processes on the gas-solid interface are modeled with allowance for diffusion. Approaches are proposed to describe the adsorbate distribution on the solid body surface at the intermolecular interactions level. The potentials of the intermolecular interaction of water-water, water-methane and methane-methane were used to adequately modeling the real physical and chemical processes. The energies calculated by the B3LYP/aug-cc-pVDZ method. Computational algorithms for determining the average molecule area in a dense monolayer, are considered here. Differences in modeling approaches are also given: that of the proposed in this work and the previously approved probabilistic cellular automaton (PCA) method. It has been shown that the main difference is due to certain limitations of the PCA method. The importance of accounting the intermolecular interactions via hydrogen bonding has been indicated. Further development of the adsorption-desorption processes modeling will allow to find the conditions for of surface processes regulation by means of quantity adsorbed molecules control. The proposed approach to representing the molecular system significantly shortens the calculation time in comparison with the use of atom-atom potentials. In the future, this will allow to modeling the multilayer adsorption at a reasonable computational cost.

Microwave Irradiation Assisted Preparation of Chitosan Composite Microsphere for Dye Adsorption

Directory of Open Access Journals (Sweden)

Xiaoyu Chen

2017-01-01

Full Text Available Chitosan-activated carbon composite microspheres were prepared by emulsion cross-linking method and its adsorption properties for methyl orange were studied. Chitosan solution was mixed with activated carbon powder and then chitosan was cross-linked by epichlorohydrin under microwave irradiation. SEM photos show that the composite microspheres have diameters of 200–400 μm and activated carbon powder dispersed on the surface of composite microsphere. FTIR spectrum indicates chitosan is successfully cross-linked. Microwave irradiation can effectively shorten the cross-linking time. Composite microspheres have enhanced dye adsorption capacity for methyl orange compared to chitosan microspheres. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Isotherm studies show that the isotherm adsorption equilibrium is better described by Freundlich isotherm. Regeneration results show that adsorption capacity of composite microsphere decreased about 5.51% after being reused for three times. These results indicated that chitosan-activated carbon composite microsphere has potential application in the removal of dye from wastewaters.

Adsorption of metals on metal surfaces and the possibilities of its application in nuclear chemistry

International Nuclear Information System (INIS)

Roesch, F.; Eichler, B.

1986-01-01

Starting with values of differential enthalpies of adsorption ΔH-bar/sub a/ the desorption temperatures of 65 adsorptive metals as to 40 adsorbens metals have been obtained according to a model calculation. With regard to their potential separation by means of selective desorption from solid metal surfaces the desorption behaviour of combinations of radionuclides Me 1 (proton number Z)/Me 2 (proton number Z+1) and Me 1 (proton number Z)/Me 2 (proton number Z+2) was calculated. Basing on the parameters of the model assumptions, the results of the calculations allow estimations about the desorption temperatures of the adsorptive Me 1 as well as the temperature differences to the desorption of the adsorptive Me 2 and about the efficiency of the potential separation process. (author)

Adsorption of a single polymer chain on a surface: effects of the potential range.

Science.gov (United States)

Klushin, Leonid I; Polotsky, Alexey A; Hsu, Hsiao-Ping; Markelov, Denis A; Binder, Kurt; Skvortsov, Alexander M

2013-02-01

We investigate the effects of the range of adsorption potential on the equilibrium behavior of a single polymer chain end-attached to a solid surface. The exact analytical theory for ideal lattice chains interacting with a planar surface via a box potential of depth U and width W is presented and compared to continuum model results and to Monte Carlo (MC) simulations using the pruned-enriched Rosenbluth method for self-avoiding chains on a simple cubic lattice. We show that the critical value U(c) corresponding to the adsorption transition scales as W(-1/ν), where the exponent ν=1/2 for ideal chains and ν≈3/5 for self-avoiding walks. Lattice corrections for finite W are incorporated in the analytical prediction of the ideal chain theory U(c)≈(π(2)/24)(W+1/2)(-2) and in the best-fit equation for the MC simulation data U(c)=0.585(W+1/2)(-5/3). Tail, loop, and train distributions at the critical point are evaluated by MC simulations for 1≤W≤10 and compared to analytical results for ideal chains and with scaling theory predictions. The behavior of a self-avoiding chain is remarkably close to that of an ideal chain in several aspects. We demonstrate that the bound fraction θ and the related properties of finite ideal and self-avoiding chains can be presented in a universal reduced form: θ(N,U,W)=θ(NU(c),U/U(c)). By utilizing precise estimations of the critical points we investigate the chain length dependence of the ratio of the normal and lateral components of the gyration radius. Contrary to common expectations this ratio attains a limiting universal value /=0.320±0.003 only at N~5000. Finite-N corrections for this ratio turn out to be of the opposite sign for W=1 and for W≥2. We also study the N dependence of the apparent crossover exponent φ(eff)(N). Strong corrections to scaling of order N(-0.5) are observed, and the extrapolated value φ=0.483±0.003 is found for all values of W. The strong correction to scaling effects found here explain why

Adsorption of Chrysoidine R by using fly ash in batch process

International Nuclear Information System (INIS)

Matheswaran, Manickam; Karunanithi, Thirugnanam

2007-01-01

This investigation deals with effective utilization of fly ash as adsorbent for the removal of Chrysoidine R from the aqueous solution. The fly ash is a major byproduct generated in coal-based thermal power plants and has good potential for use as an adsorbent. A series of experiments were carried out in a batch adsorption technique to obtain the effect of process variables viz. contact time, pH (2, 4, 6 and 8) initial concentration of the dye (400, 600, 800 and 1000 mg L -1 ), amount of the adsorbent (125, 250, 375 and 500 mg L -1 ), and temperature (303, 313, 323 and 333 K) on adsorption. The concentration of dye was determined by spectrophotometer. The results showed that as the amount of the adsorbent was increased, the percentage of dye removal increased accordingly; higher adsorption percentage was observed at lower concentration of chrysoidine. The adsorption data were analyzed using Langmuir and Freundlich isotherms. The adsorption was found to obey pseudo-first order kinetics. An intra particle diffusion model was used to fit the experimental data. The thermodynamic parameters such as standard change in free energy, enthalpy and entropy of adsorption have been calculated. Adsorption of Chrysoidine R on fly ash was found to be an exothermic reaction

Removal of heavy metals and pollutants by membrane adsorption techniques

Science.gov (United States)

Khulbe, K. C.; Matsuura, T.

2018-03-01

Application of polymeric membranes for the adsorption of hazardous pollutants may lead to the development of next-generation reusable and portable water purification appliances. Membranes for membrane adsorption (MA) have the dual function of membrane filtration and adsorption to be very effective to remove trace amounts of pollutants such as cationic heavy metals, anionic phosphates and nitrates. In this review article, recent progresses in the development of MA membranes are surveyed. In addition, recent progresses in the development of advanced adsorbents such as nanoparticles are summarized, since they are potentially useful as fillers in the host membrane to enhance its performance. The future directions of R&D in this field are also shown in the conclusion section.

Feasibility study on the application of a heat-pipe type adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sang Hyeok; Chung, Jae Dong [Dept. of Mechanical Engineering, Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Energy System R and D Group, Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)

2017-01-15

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl{sub 2}) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature.

Surface complexation modeling of the effects of phosphate on uranium(VI) adsorption

Energy Technology Data Exchange (ETDEWEB)

Romero-Gonzalez, M.R.; Cheng, T.; Barnett, M.O. [Auburn Univ., AL (United States). Dept. of Civil Engeneering; Roden, E.E. [Wisconsin Univ., Madison, WI (United States). Dept. of Geology and Geophysics

2007-07-01

Previous published data for the adsorption of U(VI) and/or phosphate onto amorphous Fe(III) oxides (hydrous ferric oxide, HFO) and crystalline Fe(III) oxides (goethite) was examined. These data were then used to test the ability of a commonly-used surface complexation model (SCM) to describe the adsorption of U(VI) and phosphate onto pure amorphous and crystalline Fe(III) oxides and synthetic goethite-coated sand, a surrogate for a natural Fe(III)-coated material, using the component additivity (CA) approach. Our modeling results show that this model was able to describe U(VI) adsorption onto both amorphous and crystalline Fe(III) oxides and also goethite-coated sand quite well in the absence of phosphate. However, because phosphate adsorption exhibits a stronger dependence on Fe(III) oxide type than U(VI) adsorption, we could not use this model to consistently describe phosphate adsorption onto both amorphous and crystalline Fe(III) oxides and goethite-coated sand. However, the effects of phosphate on U(VI) adsorption could be incorporated into the model to describe U(VI) adsorption to both amorphous and crystalline Fe(III) oxides and goethite-coated sand, at least for an initial approximation. These results illustrate both the potential and limitations of using surface complexation models developed from pure systems to describe metal/radionuclide adsorption under more complex conditions. (orig.)

Surface complexation modeling of the effects of phosphate on uranium(VI) adsorption

International Nuclear Information System (INIS)

Romero-Gonzalez, M.R.; Cheng, T.; Barnett, M.O.; Roden, E.E.

2007-01-01

Previous published data for the adsorption of U(VI) and/or phosphate onto amorphous Fe(III) oxides (hydrous ferric oxide, HFO) and crystalline Fe(III) oxides (goethite) was examined. These data were then used to test the ability of a commonly-used surface complexation model (SCM) to describe the adsorption of U(VI) and phosphate onto pure amorphous and crystalline Fe(III) oxides and synthetic goethite-coated sand, a surrogate for a natural Fe(III)-coated material, using the component additivity (CA) approach. Our modeling results show that this model was able to describe U(VI) adsorption onto both amorphous and crystalline Fe(III) oxides and also goethite-coated sand quite well in the absence of phosphate. However, because phosphate adsorption exhibits a stronger dependence on Fe(III) oxide type than U(VI) adsorption, we could not use this model to consistently describe phosphate adsorption onto both amorphous and crystalline Fe(III) oxides and goethite-coated sand. However, the effects of phosphate on U(VI) adsorption could be incorporated into the model to describe U(VI) adsorption to both amorphous and crystalline Fe(III) oxides and goethite-coated sand, at least for an initial approximation. These results illustrate both the potential and limitations of using surface complexation models developed from pure systems to describe metal/radionuclide adsorption under more complex conditions. (orig.)

Feasibility study on the application of a heat-pipe type adsorption chiller

International Nuclear Information System (INIS)

Ahn, Sang Hyeok; Chung, Jae Dong; Kwon, Oh Kyung

2017-01-01

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl_2) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature

Adsorption of copper to different biogenic oyster shell structures

Energy Technology Data Exchange (ETDEWEB)

Wu, Qiong; Chen, Jie [College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian Province 350108 (China); Clark, Malcolm [Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, P.O. Box 157, Lismore, NSW 2480 (Australia); Yu, Yan, E-mail: yuyan_1972@126.com [College of Materials Science and Engineering, Fuzhou University, New Campus, Minhou, Fujian Province 350108 (China)

2014-08-30

Graphical abstract: - Highlights: • Adsorption of copper to waste oyster shell occurs rapidly at pH 5.5. • Copper adsorbs to the different structures of oyster shell at different rates. • The prismatic layer dominates copper sorption rather than the nacreous layer. • SEM analysis shows a porous open network structure to the prismatic layer. • Surface ζ-potentials establish electrostatic attraction to drive copper sorption. - Abstract: The removal of copper from solution by oyster shell powder was investigated for potential wastewater treatment uses. In particular, adsorption behavior differences between the prismatic (PP) and nacreous (NP) shell layers, and how this affects copper removal, were investigated. Experimental results indicated that copper adsorption was highly pH-dependent with optimal copper removal at pH 5.5, where the powdered whole raw shell (RP) removed up to 99.9% of the copper within 24 h at a 10 mg/L initial copper concentration. Langmuir and Freundlich models were used to analyze the isotherm PP, NP and RP data. These results showed a strong homogeneous Langmuir model for low initial copper concentrations (5–30 mg/L) to both RP and PP layer, while strong agreement with a heterogeneous Freundlich model for high initial copper concentrations (30–200 mg/L); nevertheless, a homogeneous Langmuir model provided the best fit for the more dense NP layer across the initial concentration range (5–200 mg/L). The distribution coefficient (K{sub d}) value of PP layer for each initial concentration investigated was substantially higher than the NP layer and it was also found that the PP layer dominated the adsorption process with an adsorption capacity of 8.9 mg/g, while the adsorption capacity of the NP layer was 2.6 mg/g. These differences are believed to be because of the more porous structure of the PP layer, which was confirmed by scanning electron microscopy, infrared spectroscopy, energy-dispersive X-ray spectroscopy, and

Adsorption of copper to different biogenic oyster shell structures

International Nuclear Information System (INIS)

Wu, Qiong; Chen, Jie; Clark, Malcolm; Yu, Yan

2014-01-01

Graphical abstract: - Highlights: • Adsorption of copper to waste oyster shell occurs rapidly at pH 5.5. • Copper adsorbs to the different structures of oyster shell at different rates. • The prismatic layer dominates copper sorption rather than the nacreous layer. • SEM analysis shows a porous open network structure to the prismatic layer. • Surface ζ-potentials establish electrostatic attraction to drive copper sorption. - Abstract: The removal of copper from solution by oyster shell powder was investigated for potential wastewater treatment uses. In particular, adsorption behavior differences between the prismatic (PP) and nacreous (NP) shell layers, and how this affects copper removal, were investigated. Experimental results indicated that copper adsorption was highly pH-dependent with optimal copper removal at pH 5.5, where the powdered whole raw shell (RP) removed up to 99.9% of the copper within 24 h at a 10 mg/L initial copper concentration. Langmuir and Freundlich models were used to analyze the isotherm PP, NP and RP data. These results showed a strong homogeneous Langmuir model for low initial copper concentrations (5–30 mg/L) to both RP and PP layer, while strong agreement with a heterogeneous Freundlich model for high initial copper concentrations (30–200 mg/L); nevertheless, a homogeneous Langmuir model provided the best fit for the more dense NP layer across the initial concentration range (5–200 mg/L). The distribution coefficient (K d ) value of PP layer for each initial concentration investigated was substantially higher than the NP layer and it was also found that the PP layer dominated the adsorption process with an adsorption capacity of 8.9 mg/g, while the adsorption capacity of the NP layer was 2.6 mg/g. These differences are believed to be because of the more porous structure of the PP layer, which was confirmed by scanning electron microscopy, infrared spectroscopy, energy-dispersive X-ray spectroscopy, and

Prediction of Pure Component Adsorption Equilibria Using an Adsorption Isotherm Equation Based on Vacancy Solution Theory

DEFF Research Database (Denmark)

Marcussen, Lis; Aasberg-Petersen, K.; Krøll, Annette Elisabeth

2000-01-01

An adsorption isotherm equation for nonideal pure component adsorption based on vacancy solution theory and the Non-Random-Two-Liquid (NRTL) equation is found to be useful for predicting pure component adsorption equilibria at a variety of conditions. The isotherm equation is evaluated successfully...... adsorption systems, spreading pressure and isosteric heat of adsorption are also calculated....

Fundamentals of high pressure adsorption

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.P.; Zhou, L. [Tianjin University, Tianjin (China). High Pressure Adsorption Laboratory

2009-12-15

High-pressure adsorption attracts research interests following the world's attention to alternative fuels, and it exerts essential effect on the study of hydrogen/methane storage and the development of novel materials addressing to the storage. However, theoretical puzzles in high-pressure adsorption hindered the progress of application studies. Therefore, the present paper addresses the major theoretical problems that challenged researchers: i.e., how to model the isotherms with maximum observed in high-pressure adsorption; what is the adsorption mechanism at high pressures; how do we determine the quantity of absolute adsorption based on experimental data. Ideology and methods to tackle these problems are elucidated, which lead to new insights into the nature of high-pressure adsorption and progress in application studies, for example, in modeling multicomponent adsorption, hydrogen storage, natural gas storage, and coalbed methane enrichment, was achieved.

Adsorption of CO molecules on doped graphene: A first-principles study

Directory of Open Access Journals (Sweden)

Weidong Wang

2016-02-01

Full Text Available As a typical kinds of toxic gases, CO plays an important role in environmental monitoring, control of chemical processes, space missions, agricultural and medical applications. Graphene is considered a potential candidate of gases sensor, so the adsorption of CO molecules on various graphene, including pristine graphene, Nitrogen-doped graphene (N-doped graphene and Aluminum-doped graphene (Al-doped graphene, are studied by using first-principles calculations. The optimal configurations, adsorption energies, charge transfer, and electronic properties including band structures, density of states and differential charge density are obtained. The adsorption energies of CO molecules on pristine graphene and N-doped graphene are −0.01 eV, and −0.03 eV, respectively. In comparison, the adsorption energy of CO on Al-doped graphene is much larger, −2.69 eV. Our results also show that there occurs a large amount of charge transfer between CO molecules and graphene sheet after the adsorption, which suggests Al-doped graphene is more sensitive to the adsorption of CO than pristine graphene and N-doped graphene. Therefore, the sensitivity of gases on graphene can be drastically improved by introducing the suitable dopants.

Surface study of platinum decorated graphene towards adsorption of NH_3 and CH_4

International Nuclear Information System (INIS)

Rad, Ali Shokuhi; Pazoki, Hossein; Mohseni, Soheil; Zareyee, Daryoush; Peyravi, Majid

2016-01-01

To distinguish the potential of graphene sensors, there is a need to recognize the interaction between graphene sheet and adsorbing molecules. We used density functional theory (DFT) calculations to study the properties of pristine as well as Pt-decorated graphene sheet upon adsorption of NH_3 and CH_4 on its surface to exploit its potential to be as gas sensors for them. We found much higher adsorption, higher charge transfer, lower intermolecular distance, and higher orbital hybridizing upon adsorption of NH_3 and CH_4 gas molecules on Pt-decorated graphene compared to pristine graphene. Also our calculations reveal that the adsorption energies on Pt-decorated graphene sheet are in order of NH_3 >CH_4 which could be corresponded to the order of their sensitivity on this modified surface. We used orbital analysis including density of states as well as frontier molecular orbital study for all analyte-surface systems to more understanding the kind of interaction (physisorption or chemisorption). Consequently, the Pt-decorated graphene can transform the existence of NH_3 and CH_4 molecules into electrical signal and it may be potentially used as an ideal sensor for detection of NH_3 and CH_4 in ambient situation. - Highlights: • Pt-decorated graphene was investigated as an adsorbent for NH_3 and CH_4. • Much higher adsorption of NH_3 and CH_4 on Pt-decorated graphene than pristine graphene. • Higher adsorption of NH_3 compared to CH_4 on Pt-decorated graphene. • Pt influences the electronic structure of graphene.

Adsorption of dyes onto activated carbon cloth: using QSPRs as tools to approach adsorption mechanisms.

Science.gov (United States)

Metivier-Pignon, Hélène; Faur, Catherine; Le Cloirec, Pierre

2007-01-01

The present study aimed to investigate the adsorption of dyes onto activated carbon cloths. Kinetics and isotherms were studied based on results of batch reactors to constitute databases for the adsorption rates and capacities of 22 commercial dyes. Added to a qualitative analysis of experimental results, quantitative structure property relationships (QSPRs) were used to determine the structural features that influence most adsorption processes. QSPRs consisted of multiple linear regressions correlating adsorption parameters with molecular connectivity indices (MCIs) as molecular descriptors. Results related to adsorption kinetics showed that the size of molecules was the significant feature, the high order MCIs involved in QSPRs indicating the influence of a critical size on adsorption rate. Improved statistical fits were obtained when the database was divided according to the chemical classes of dyes. As regards to adsorption isotherms, their particular form led to the use of saturation capacity as the adsorption parameter. By contrast with adsorption kinetics, molecular overcrowding seemed to be of less influence on adsorption equilibrium. In this case, MCIs included in the QSPR were more related to details of the molecular structure. The robustness of the QSPR assessed for azo dyes was studied for the other dyes. Although the small size of the database limited predictive ability, features relevant to the influence of the database composition on QSPRs have been highlighted.

Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder

International Nuclear Information System (INIS)

Weng, Chih-Huang; Lin, Yao-Tung; Tzeng, Tai-Wei

2009-01-01

The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 x 10 -4 to 9.28 x 10 -4 mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution.

Removal of methylene blue from aqueous solution by adsorption onto pineapple leaf powder

Energy Technology Data Exchange (ETDEWEB)

Weng, Chih-Huang, E-mail: chweng@isu.edu.tw [Department of Civil and Ecological Engineering, I-Shou University, Da-Hsu Township, Kaohsiung 84008, Taiwan (China); Lin, Yao-Tung; Tzeng, Tai-Wei [Department of Soil and Environmental Sciences, National Chung Hsing University, TaiChung 40227, Taiwan (China)

2009-10-15

The ability of an unconventional bio-adsorbent, pineapple leaf powder (PLP) for the adsorption of methylene blue (MB) from aqueous solution was studied. It was observed that intra-particle diffusion was involved in the adsorption process and that the kinetic data fitted well with a pseudo-second-order equation. Fitting parameters revealed that the rate of adsorption increased with decrease in dye concentration and decrease in ionic strength while the mixing speed did not have a significant effect on adsorption. The adsorption was favorable at higher pH and lower temperature, and the equilibrium data were well fitted by the Langmuir isotherm. The maximum adsorption capacity varied from 4.68 x 10{sup -4} to 9.28 x 10{sup -4} mol/g when pH increases from 3.5 to 9.5. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, and exothermic in nature. The results revealed that this agricultural waste has potential to be used as an economical adsorbent for the removal of methylene blue from aqueous solution.

Adsorption Properties of Doxorubicin Hydrochloride onto Graphene Oxide: Equilibrium, Kinetic and Thermodynamic Studies

Directory of Open Access Journals (Sweden)

Zonghua Wang

2013-05-01

Full Text Available Doxorubicin hydrochloride (DOX is an effective anticancer agent for leukemia chemotherapy, although its clinical use has been limited because of its side effects such as cardiotoxicity, alopecia, vomiting, and leucopenia. Attention has been focussed on developing new drug carriers with high adsorption capacity and rapid adsorption rate in order to minimize the side effects of DOX. Graphene oxide (GO, a new type of nanomaterial in the carbon family, was prepared by Hummers method and used as adsorbent for DOX from aqueous solution. The physico-chemical properties of GO were characterized by transmission electron microscope (TEM, Fourier transform infrared spectroscopy (FTIR, zeta potential, and element analysis. The adsorption properties of DOX on GO were studied as a function of contact time, adsorbent dosage, temperature and pH value. The results showed that GO had a maximum adsorption capacity of 1428.57 mg/g and the adsorption isotherm data fitted the Langmuir model. The kinetics of adsorption fits a pseudo-second-order model. The thermodynamic studies indicate that the adsorption of DOX on GO is spontaneous and endothermic in nature.

Protein Adsorption to In-Line Filters of Intravenous Administration Sets.

Science.gov (United States)

Besheer, Ahmed

2017-10-01

Ensuring compatibility of administered therapeutic proteins with intravenous administration sets is an important regulatory requirement. A low-dose recovery during administration of low protein concentrations is among the commonly observed incompatibilities, and it is mainly due to adsorption to in-line filters. To better understand this phenomenon, we studied the adsorption of 4 different therapeutic proteins (2 IgG1s, 1 IgG4, and 1 Fc fusion protein) diluted to 0.01 mg/mL in 5% glucose (B. Braun EcoFlac; B. Braun Melsungen AG, Melsungen, Germany) or 0.9% sodium chloride (NaCl; Freeflex; Fresenius Kabi, Friedberg, Germany) solutions to 8 in-line filters (5 positively charged and 3 neutral filters made of different polymers and by different suppliers). The results show certain patterns of protein adsorption, which depend to a large extent on the dilution solution and filter material, and to a much lower extent on the proteins' biophysical properties. Investigation of the filter membranes' zeta potential showed a correlation between the observed adsorption pattern in 5% glucose solution and the filter's surface charge, with higher protein adsorption for the strongly negatively charged membranes. In 0.9% NaCl solution, the surface charges are masked, leading to different adsorption patterns. These results contribute to the general understanding of the protein adsorption to IV infusion filters and allow the design of more efficient compatibility studies. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

Energy Technology Data Exchange (ETDEWEB)

Contescu, Cristian I. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gallego, Nidia C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Thibaud-Erkey, Catherine [United Technologies Research Center (UTRC), East Hartford, CT (United States); Karra, Reddy [United Technologies Research Center (UTRC), East Hartford, CT (United States)

2016-04-01

The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC for measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.

Interaction of cement model systems with superplasticizers investigated by atomic force microscopy, zeta potential, and adsorption measurements.

Science.gov (United States)

Ferrari, Lucia; Kaufmann, Josef; Winnefeld, Frank; Plank, Johann

2010-07-01

Polyelectrolyte-based dispersants are commonly used in a wide range of industrial applications to provide specific workability to colloidal suspensions. Their working mechanism is based on adsorption onto the surfaces of the suspended particles. The adsorbed polymer layer can exercise an electrostatic and/or a steric effect which is responsible for achieving dispersion. This study is focused on the dispersion forces induced by polycarboxylate ether-based superplasticizers (PCEs) commonly used in concrete. They are investigated by atomic force microscopy (AFM) applying standard silicon nitride tips exposed to solutions with different ionic compositions in a wet cell. Adsorption isotherms and zeta potential analysis were performed to characterize polymer displacement in the AFM system on nonreactive model substrates (quartz, mica, calcite, and magnesium oxide) in order to avoid the complexity of cement hydration products. The results show that PCE is strongly adsorbed by positively charged materials. This fact reveals that, being silicon nitride naturally positively charged, in most cases the superplasticizer adsorbs preferably on the silicon nitride tip than on the AFM substrate. However, the force-distance curves displayed repulsive interactions between tip and substrates even when polymer was poorly adsorbed on both. These observations allow us to conclude that the dispersion due to PCE strongly depends on the particle charge. It differs between colloids adsorbing and not adsorbing PCE, and leads to different forces acting between the particles. Copyright 2010 Elsevier Inc. All rights reserved.

Enhanced adsorption of methylene blue by citric acid modification of biochar derived from water hyacinth (Eichornia crassipes).

Science.gov (United States)

Xu, Yan; Liu, Yunguo; Liu, Shaobo; Tan, Xiaofei; Zeng, Guangming; Zeng, Wei; Ding, Yang; Cao, Weicheng; Zheng, Bohong

2016-12-01

In this work, a novel potential adsorbent, citric acid (CA)-modified biochar, named as CAWB, was obtained from water hyacinth biomass by slow pyrolysis in a N 2 environment at 300 °C. The CA modification focused on enhancing the contaminants adsorption capacity of biochar pyrolyzed at relatively low temperature. Over 90 % of the total methylene blue (MB) could be removed at the first 60 min by CAWB, and the maximum MB adsorption capacity could reach to 395 mg g -1 . The physicochemical properties of CAWB was examined by FTIR, XPS, SEM, and BET analysis. The results indicated that the additional carboxyl groups were introduced to the surface of CAWB via the esterification reaction with CA, which played a significant role in the adsorption of MB. Batch adsorption studies showed that the initial MB concentration, solution pH, background ionic strength, and temperature could affect the removal efficiency obviously. The adsorption process could be well described by the pseudo-second-order kinetic model and Langmuir isotherm. Thermodynamic analysis revealed that the MB adsorption onto CAWB was an endothermic and spontaneous process. The regeneration study revealed that CAWB still exhibited an excellent regeneration and adsorption performance after multiple cycle adsorptions. The adsorption experiments of actual dye wastewater by CAWB suggested that it had a great potential in environmental application.

Adsorption of triton X100 and potassium hydrogen phthalate on granular activated carbon from date pits

Energy Technology Data Exchange (ETDEWEB)

Merzougui, Z.; Nedjah, S.; Azoudj, Y.; Addoun, F. [Laboratoire d' etude physic-chimique des materiaux et application a l' environnement, Faculte de Chimie, USTHB (Algeria)], E-mail: zmerzougi@yahoo.fr

2011-07-01

Activated carbons, thanks to their versatility, are being used in the water treatment sector to absorb pollutants. Several factors influence the adsorption capacity of activated carbon and the aim of this study was to assess the effects of the porous texture and chemical nature of activated carbons on the adsorption of triton X100 and potassium hydrogen phthalate. Activated carbons used in this study were prepared from date pits with ZnCl2, KOH and H3PO4 by carbonization without adjuvant and adsorption of triton X100 and potassium hydrogen phthalate was conducted at 298K. Results showed that activated carbons prepared from date pits have a great potential for removing organic and inorganic pollutants from water and that the adsorption potential depends on the degree of activation of the activated carbons and on the compounds to absorb. This study highlighted that an increase of the carbon surface area and porosity results in a better adsorption capacity.

Adsorption kinetics of surfactants on activated carbon

Science.gov (United States)

Arnelli; Aditama, WP; Fikriani, Z.; Astuti, Y.

2018-04-01

A study on the adsorption of both cationic and anionic surfactants using activated carbon as well as the investigation of the adsorption isotherms and adsorption kinetics has been conducted. The results showed that the adsorption of sodium lauryl sulfate (SLS) by activated carbon was Langmuir’s adsorption isotherm while its adsorption kinetics showed pseudo-second order with an adsorption rate constant of 2.23 x 103 g mg-1 hour-1. Meanwhile, the adsorption of HDTMA-Br by activated carbon showed that the isotherm adsorption tended to follow Freundlich’s isotherm and was pseudo-second order with an adsorption rate constant of 89.39 g mg-1 hour-1.

Adsorption Desalination: A Novel Method

KAUST Repository

Ng, Kim Choon

2010-11-15

The search for potable water for quenching global thirst remains a pressing concern throughout many regions of the world. The demand for new and sustainable sources and the associated technologies for producing fresh water are intrinsically linked to the solving of potable water availability and hitherto, innovative and energy efficient desalination methods seems to be the practical solutions. Quenching global thirst by adsorption desalination is a practical and inexpensive method of desalinating the saline and brackish water to produce fresh water for agriculture irrigation, industrial, and building applications. This chapter provides a general overview of the adsorption fundamentals in terms of adsorption isotherms, kinetics, and heat of adsorption. It is then being more focused on the principles of thermally driven adsorption desalination methods. The recent developments of adsorption desalination plants and the effect of operating conditions on the system performance in terms of specific daily water production and performance ratio are presented. Design of a large commercial adsorption desalination plant is also discussed herein.

Methylene blue adsorption from aqueous solution by dehydrated peanut hull

Energy Technology Data Exchange (ETDEWEB)

Ozer, Dursun [Department of Chemical Engineering, Firat University, 23279 Elazig (Turkey); Dursun, Guelbeyi [Department of Chemical Engineering, Firat University, 23279 Elazig (Turkey)]. E-mail: gdursun@firat.edu.tr; Ozer, Ahmet [Department of Chemical Engineering, Firat University, 23279 Elazig (Turkey)

2007-06-01

Dyes are colour organic compounds which can colorize the other substances. These substances usually presents in the effluent water of many industries, such as textiles, leather, paper, printing and cosmetics. To observe the potential feasibility of removing colour, peanut hull as an agricultural by-product was dehydrated with sulphuric acid (DPH) and used for adsorption of methylene blue (MB) from aqueous solution. The effects of various parameters such as initial methylene blue concentrations, temperatures and particle sizes were examined and optimal experimental conditions were determined. Adsorption data were well described by the Langmuir model, although they could be modelled by the Freundlich model as well. The adsorption process followed the pseudo-second order kinetic model. The mass transfer model as intraparticle diffusion was applied to the experimental data to examine the mechanisms of rate controlling step. It was found that at the higher initial MB concentration, intraparticle diffusion is becoming significant controlling step. The thermodynamic constants of the adsorption process were also evaluated by using the Langmuir constants related to the equilibrium of adsorption at different temperatures. The results in this study indicated that dehydrated peanut hull was a good adsorbent for removing methylene blue.

Adsorption of Cu, As, Pb and Zn by Banana Trunk

International Nuclear Information System (INIS)

Nurzulaifa Shaheera Erne Mohd Yasim; Zitty Sarah Ismail; Suhanom Mohd Zaki; Mohd Fahmi Abd Azis

2016-01-01

The purpose of this study is to investigate the effectiveness of banana trunk as an adsorbent in removal of heavy metals in aqueous solution. Functional groups of adsorbent were determined using Fourier Transform Infrared spectroscopy (FTIR). Batch experiments were conducted to determine the adsorption percentage of heavy metals (Cu, As, Pb and Zn). The optimum adsorption using banana trunk was based on pH difference, contact time and dosage. Adsorption percentage was found to be proportional to pH, contact time and dosage. Maximum adsorption percentage of Cu, As, Pb and Zn at pH 6, 100 minutes and 8 gram of dosage are 95.80 %, 75.40 %, 99.36 % and 97.24 %, respectively. Langmuir and Freundlich isotherms were used to determine the equilibrium state for heavy metals ion adsorption experiments. All equilibrium heavy metals were well explained by the Freundlich isotherm model with R"2= 0.9441, R"2= 0.8671, R"2= 0.9489 and R"2= 0.9375 for Cu, As, Pb and Zn respectively. It is concluded that banana trunk has considerable potential for the removal of heavy metals from aqueous solution. (author)

Surface metal adsorption on zooplankton carapaces: implications for exposure and effects in consumer organisms

International Nuclear Information System (INIS)

Robinson, K.A.; Baird, D.J.; Wrona, F.J.

2003-01-01

Metals adsorbed to prey surfaces may be a mechanism of exposure in predators. - The current study aimed to determine the potential of two important aquatic invertebrate crustacean species, Daphnia magna and Ceriodaphnia dubia, to adsorb cadmium on to their carapaces from aqueous solution. Using the Langmuir equation to model data outputs, it was shown that cadmium readily became associated with the carapace surfaces of both species, with uptake being dependent on exposure time and concentration. Maximum carapace-adsorption potential was found to be directly related to surface area, so that at predicted carapace saturation, D. magna neonates bound approximately five times more cadmium than the smaller C. dubia neonates. However, adsorption per unit surface area was found to be similar under the same exposure conditions. Results of surface metal adsorption studies in C. dubia suggested that short term exposures to high concentrations of aqueous cadmium would lead to similar levels of adsorption as obtained with long-term exposures to low concentrations. The study illustrates that contaminants adsorbed to prey surfaces may be an important mechanism of exposure to predators, and highlights some potential problems of feeding organisms during long-term toxicity tests

Aluminum and iron doped graphene for adsorption of methylated arsenic pollutants

Energy Technology Data Exchange (ETDEWEB)

Cortés-Arriagada, Diego, E-mail: dcarriagada@gmail.com; Toro-Labbé, Alejandro

2016-11-15

Graphical abstract: Quantum chemistry calculations show the ability of aluminum and iron doped graphene for the removal of methylated arsenicals in their trivalent and pentavalent states, with adsorption energies on the range of 1.5–4.2 eV, and high stability in a water environment. Display Omitted - Highlights: • Al and Fe-doped graphene serve as superior materials for adsorption of methylated arsenicals, including thioarsenicals. • Pentavalent arsenicals are adsorbed with higher adsorption energies (up to 4.2 eV) than trivalent arsenicals (up to 1.7 eV). • The adsorption strength is determined by the weakening of the interacting σAs−O bond in the pollutant. • The adsorption stability was studied in a water environment and molecular dynamics calculations were performed at 300 K. • Trivalent and petavalent forms are mainly adsorbed at neutral pH in their neutral and anionic forms, respectively. - Abstract: The ability of Al and Fe-doped graphene for the adsorption of trivalent and pentavalent methylated arsenic compounds was studied by quantum chemistry computations. The adsorption of trivalent methylarsenicals is reached with adsorption energies of 1.5–1.7 eV at neutral conditions; while, adsorption of pentavalent methylarsenicals reaches adsorption energies of 3.3–4.2 eV and 1.2–2.4 eV from neutral to low pH conditions, respectively. Moreover, the weakening of the interacting σAs−O bond in the pollutant structure played an important role in the stability of the adsorbent–adsorbate systems, determining the adsorption strength. In addition, the pollutant adsorption appears to be efficient in aqueous environments, with even high stability at ambient temperature; in this regard, it was determined that the trivalent and petavalent forms are mainly adsorbed in their neutral and anionic forms at neutral pH, respectively. Therefore, Al and Fe-doped graphene are considered as potential future materials for the removal of methylated arsenic

Aluminum and iron doped graphene for adsorption of methylated arsenic pollutants

International Nuclear Information System (INIS)

Cortés-Arriagada, Diego; Toro-Labbé, Alejandro

2016-01-01

Graphical abstract: Quantum chemistry calculations show the ability of aluminum and iron doped graphene for the removal of methylated arsenicals in their trivalent and pentavalent states, with adsorption energies on the range of 1.5–4.2 eV, and high stability in a water environment. Display Omitted - Highlights: • Al and Fe-doped graphene serve as superior materials for adsorption of methylated arsenicals, including thioarsenicals. • Pentavalent arsenicals are adsorbed with higher adsorption energies (up to 4.2 eV) than trivalent arsenicals (up to 1.7 eV). • The adsorption strength is determined by the weakening of the interacting σAs−O bond in the pollutant. • The adsorption stability was studied in a water environment and molecular dynamics calculations were performed at 300 K. • Trivalent and petavalent forms are mainly adsorbed at neutral pH in their neutral and anionic forms, respectively. - Abstract: The ability of Al and Fe-doped graphene for the adsorption of trivalent and pentavalent methylated arsenic compounds was studied by quantum chemistry computations. The adsorption of trivalent methylarsenicals is reached with adsorption energies of 1.5–1.7 eV at neutral conditions; while, adsorption of pentavalent methylarsenicals reaches adsorption energies of 3.3–4.2 eV and 1.2–2.4 eV from neutral to low pH conditions, respectively. Moreover, the weakening of the interacting σAs−O bond in the pollutant structure played an important role in the stability of the adsorbent–adsorbate systems, determining the adsorption strength. In addition, the pollutant adsorption appears to be efficient in aqueous environments, with even high stability at ambient temperature; in this regard, it was determined that the trivalent and petavalent forms are mainly adsorbed in their neutral and anionic forms at neutral pH, respectively. Therefore, Al and Fe-doped graphene are considered as potential future materials for the removal of methylated arsenic

Guaiacol hydrodeoxygenation mechanism on Pt(111): insights from density functional theory and linear free energy relations.

Science.gov (United States)

Lee, Kyungtae; Gu, Geun Ho; Mullen, Charles A; Boateng, Akwasi A; Vlachos, Dionisios G

2015-01-01

Density functional theory is used to study the adsorption of guaiacol and its initial hydrodeoxygenation (HDO) reactions on Pt(111). Previous Brønsted-Evans-Polanyi (BEP) correlations for small open-chain molecules are inadequate in estimating the reaction barriers of phenolic compounds except for the side group (methoxy) carbon-dehydrogenation. New BEP relations are established using a select group of phenolic compounds. These relations are applied to construct a potential-energy surface of guaiacol-HDO to catechol. Analysis shows that catechol is mainly produced via dehydrogenation of the methoxy functional group followed by the CHx (x<3) removal of the functional group and hydrogenation of the ring carbon, in contrast to a hypothesis of a direct demethylation path. Dehydroxylation and demethoxylation are slow, implying that phenol is likely produced from catechol but not through its direct dehydroxylation followed by aromatic carbon-ring hydrogenation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of polyethylene glycol (PEG) onto cellulose nano-crystals to improve its dispersity.

Science.gov (United States)

Cheng, Dong; Wen, Yangbing; Wang, Lijuan; An, Xingye; Zhu, Xuhai; Ni, Yonghao

2015-06-05

In this work, the adsorption of polyethylene glycol (PEG) onto cellulose nano-crystals (CNC) was investigated for preparing re-dispersible dried CNC. Results showed that the re-dispersity of CNC in water can be significantly enhanced using a PEG1000 dosage of 5wt% (based on the dry weight of CNC). The elemental analysis confirmed the adsorption of PEG onto the CNC surface. Transmission electron microscopy (TEM) was used to characterize the dry powder and indicated that the irreversible agglomeration of CNC after drying was essentially eliminated based on the PEG adsorption concept. Thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) suggested that CNC crystallinity and thermal stability were not affected by the adsorption of PEG. Thus, the adsorption of PEG has great potential for producing re-dispersible powder CNC. Copyright © 2015 Elsevier Ltd. All rights reserved.

Theoretical insights into the uranyl adsorption behavior on vanadium carbide MXene

Science.gov (United States)

Zhang, Yu-Juan; Zhou, Zhang-Jian; Lan, Jian-Hui; Ge, Chang-Chun; Chai, Zhi-Fang; Zhang, Peihong; Shi, Wei-Qun

2017-12-01

Remediation of the contamination by long-lived actinide wastes is extremely important but also challenging. Adsorption based techniques have attracted much research attention for their potential as low-cost and effective methods to reduce the radioactive waste from solution. In this work, we have investigated the adsorption behavior of uranyl species [with the general form UO2(L1)x(L2)y(L3)z, where L1, L2 and L3 stand for ligands H2O, OH and CO3, respectively] on hydroxylated vanadium carbide V2C(OH)2 MXene nanosheets using density functional theory based simulation methods We find that all studied uranyl species can stably bond to hydroxylated MXene with binding energies ranging from -3.3 to -4.6 eV, suggesting that MXenes could be effective adsorbers for uranyl ions. The strong adsorption is achieved by forming two Usbnd O bonds with the hydroxylated Mxene. In addition, the axial oxygen atoms from the uranyl ions form hydrogen bonds with the hydroxylated V2C, further strengthening the adsorption. We have also investigated the effects of F termination on the uranyl adsorption properties of V2C nanosheets. Usbnd F bonds are in general weaker than Usbnd O bonds on the adsorption site, suggesting that F terminated Mexne is less favorable for uranyl adsorption applications.

Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

International Nuclear Information System (INIS)

Jacek Jagiello; Matthias Thommes

2005-01-01

Various microporous materials such as activated carbons, nano-tubes, synthetic microporous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP (Quantachrome Instruments, Boynton Beach, Florida, USA). As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micropores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micropores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT), and graphitized carbon black (Supelco). The Qst values decrease with increasing pore sizes. The

Kinetics Study of Gas Pollutant Adsorption and Thermal Desorption on Silica Gel

Directory of Open Access Journals (Sweden)

Rong A

2017-06-01

Full Text Available Silica gel is a typical porous desiccant material. Its adsorption performance for gaseous air pollutants was investigated to determine its potential contribution to reducing such pollutants. Three gaseous air pollutants, toluene, carbon dioxide, and methane, were investigated in this paper. A thermogravimetric analyzer was used to obtain the equilibrium adsorption capacity of gases on single silica gel particles. The silica gel adsorption capacity for toluene is much higher than that for carbon dioxide and methane. To understand gas pollutant thermal desorption from silica gel, the thermogravimetric analysis of toluene desorption was conducted with 609 ppm toluene vapor at 313 K, 323 K, and 333 K. The overall regeneration rate of silica gel was strongly dependent on temperature and the enthalpy of desorption. The gas pollutant adsorption performance and thermal desorption on silica gel material may be used to estimate the operating and design parameters for gas pollutant adsorption by desiccant wheels.

In vitro adsorption study of fluoxetine in activated carbons and activated carbon fibres

Energy Technology Data Exchange (ETDEWEB)

Nabais, J.M. Valente; Mouquinho, A.; Galacho, C.; Carrott, P.J.M.; Ribeiro Carrott, M.M.L. [Centro de Quimica de Evora e Departamento de Quimica da Universidade de Evora, Rua Romao Ramalho no. 59, 7000-671 Evora (Portugal)

2008-05-15

We study the in vitro adsorption of fluoxetine hydrochloride by different adsorbents in simulated gastric and intestinal fluid, pH 1.2 and 7.5, respectively. The tested materials were two commercial activated carbons, carbomix and maxsorb MSC30, one activated carbon fibre produced in our laboratory and also three MCM-41 samples, also produced by us. Selected samples were modified by liquid phase oxidation and thermal treatment in order to change the surface chemistry without significant modifications to the porous characteristics. The fluoxetine adsorption follows the Langmuir model. The calculated Q{sub 0} values range from 54 to 1112 mg/g. A different adsorption mechanism was found for the adsorption of fluoxetine in activated carbon fibres and activated carbons. In the first case the most relevant factors are the molecular sieving effect and the dispersive interactions whereas in the activated carbons the mechanism seams to be based on the electrostatic interactions between the fluoxetine molecules and the charged carbon surface. Despite the different behaviours most of the materials tested have potential for treating potential fluoxetine intoxications. (author)

Adsorptive removal of cesium using bio fuel extraction microalgal waste

Energy Technology Data Exchange (ETDEWEB)

Inoue, Katsutoshi, E-mail: inoue@elechem.chem.saga-u.ac.jp [Department of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo 1, Saga 840-8502 (Japan); Gurung, Manju [Department of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo 1, Saga 840-8502 (Japan); Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John' s, NL, Canada A1B 3X5 (Canada); Adhikari, Birendra Babu; Alam, Shafiq [Faculty of Engineering and Applied Science, Memorial University of Newfoundland, St. John' s, NL, Canada A1B 3X5 (Canada); Kawakita, Hidetaka; Ohto, Keisuke [Department of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo 1, Saga 840-8502 (Japan); Kurata, Minoru [Research Laboratories, DENSO CORPORATION, Minamiyama 500-1, Komenoki, Nisshin, Aichi 470-0111 (Japan); Atsumi, Kinya [New Business Promotion Dept., DENSO CORPORATION, Showa-cho 1-1, Kariya, Aichi 448-8661 (Japan)

2014-04-01

Highlights: • A novel biosorbent was prepared from the microalgal waste after biofuel extraction. • Higher selectivity and adsorption efficiency of the adsorbent for Cs{sup +} over Na{sup +} ions from aqueous solutions. • Potential candidate and eco-friendly alternative to the commercial resins such as zeolite. - Abstract: An adsorption gel was prepared from microalgal waste after extracting biodiesel oil by a simple chemical treatment of crosslinking using concentrated sulfuric acid. The adsorbent exhibited notably high selectivity and adsorption capacity towards Cs{sup +} over Na{sup +} from aqueous solutions, within the pH range of slightly acidic to neutral. The adsorption followed Langmuir isotherm and the maximum adsorption capacity of the gel for Cs{sup +} calculated from Langmuir model was found to be 1.36 mol kg{sup −1}. Trace concentration of Cs{sup +} ions present in aqueous streams was successfully separated from Na{sup +} ions using a column packed with the adsorbent at pH 6.5. The adsorption capacity of the gel towards Cs{sup +} in column operation was 0.13 mol kg{sup −1}. Although the adsorbed Cs{sup +} ions were easily eluted using 1 M hydrochloric acid solution, simple incineration is proposed as an alternative for the treatment of adsorbent loaded with radioactive Cs{sup +} ions due to the combustible characteristics of this adsorbent.

Strong Selective Adsorption of Polymers.

Science.gov (United States)

Ge, Ting; Rubinstein, Michael

2015-06-09

A scaling theory is developed for selective adsorption of polymers induced by the strong binding between specific monomers and complementary surface adsorption sites. By "selective" we mean specific attraction between a subset of all monomers, called "sticky", and a subset of surface sites, called "adsorption sites". We demonstrate that, in addition to the expected dependence on the polymer volume fraction ϕ bulk in the bulk solution, selective adsorption strongly depends on the ratio between two characteristic length scales, the root-mean-square distance l between neighboring sticky monomers along the polymer, and the average distance d between neighboring surface adsorption sites. The role of the ratio l / d arises from the fact that a polymer needs to deform to enable the spatial commensurability between its sticky monomers and the surface adsorption sites for selective adsorption. We study strong selective adsorption of both telechelic polymers with two end monomers being sticky and multisticker polymers with many sticky monomers between sticky ends. For telechelic polymers, we identify four adsorption regimes at l / d 1, we expect that the adsorption layer at exponentially low ϕ bulk consists of separated unstretched loops, while as ϕ bulk increases the layer crosses over to a brush of extended loops with a second layer of weakly overlapping tails. For multisticker chains, in the limit of exponentially low ϕ bulk , adsorbed polymers are well separated from each other. As l / d increases, the conformation of an individual polymer changes from a single-end-adsorbed "mushroom" to a random walk of loops. For high ϕ bulk , adsorbed polymers at small l / d are mushrooms that cover all the adsorption sites. At sufficiently large l / d , adsorbed multisticker polymers strongly overlap. We anticipate the formation of a self-similar carpet and with increasing l / d a two-layer structure with a brush of loops covered by a self-similar carpet. As l / d exceeds the

Selective adsorption of cationic dyes by UiO-66-NH{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Chen, Qi; He, Qinqin; Lv, Mengmeng; Xu, Yanli; Yang, Hanbiao; Liu, Xueting, E-mail: wmlxt@163.com; Wei, Fengyu, E-mail: weifyliuj@163.com

2015-02-01

Graphical abstract: - Highlights: • Two Zr(IV)-based MOFs can remove cationic dyes more effectively than anionic dyes. • UiO-66 has higher selectivity for cationic dyes after modification with NH{sub 2}. • The mechanism for adsorption selectivity is rationally proposed. - Abstract: Herein, two zirconium(IV)-based MOFs UiO-66 and UiO-66-NH{sub 2} had been successfully prepared by a facile solvothermal method and were characterized by X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), N{sub 2} adsorption–desorption (BET), X-ray photoelectron spectroscopy (XPS), and zeta potential. They exhibit small size, large surface area, and can remove cationic dyes from aqueous solution more effectively than anionic dyes. This adsorption selectivity is due to the favorable electrostatic interactions between the adsorbents and cationic dyes. Furthermore, owing to the individual micropore structure of UiO-66-NH{sub 2} and its more negative zeta potential resulted from the charge balance for the protonation of –NH{sub 2}, UiO-66-NH{sub 2} displays much higher adsorption capacity for cationic dyes and lower adsorption capacity for anionic dyes than UiO-66.

Evaluation of the in vitro differential protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (NLCs) for potential targeting to the brain.

Science.gov (United States)

Kasongo, Kasongo Wa; Jansch, Mirko; Müller, Rainer H; Walker, Roderick B

2011-09-01

The preferential in vitro adsorption of apolipoprotein E (Apo E) onto the surface of colloidal drug carriers may be used as a strategy to evaluate the in vivo potential for such systems to transport drugs to the brain. The aim of this research was to investigate the in vitro protein adsorption patterns of didanosine-loaded nanostructured lipid carriers (DDI-NLCs), using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), in order to establish the potential for NLCs to deliver DDI to the brain. NLC formulations were manufactured using high-pressure homogenization using a lipid matrix consisting of a mixture of Precirol(®) ATO 5 and Transcutol(®) HP. The 2-D PAGE analysis revealed that NLCs in formulations stabilized using Solutol(®) HS 15 alone or with a ternary surfactant system consisting of Solutol(®) HS 15, Tween(®) 80, and Lutrol(®) F68, preferentially adsorbed proteins, such as Apo E. Particles stabilized with Tween(®) 80 and Lutrol(®) F68 did not adsorb Apo E in these studies, which could be related to the relatively large particle size and hence small surface area observed for these NLCs. These findings have revealed that DDI-loaded NLCs may have the potential to deliver DDI to the brain in vivo and, in addition, to Tween(®) 80, which has already been shown to have the ability to facilitate the targeting of colloidal drug delivery systems to the brain. Solutol(®) HS 15-stabilized nanoparticles may also achieve a similar purpose.

Adsorption of formaldehyde on graphene and graphyne

Science.gov (United States)

Majidi, R.; Karami, A. R.

2014-05-01

The adsorption of formaldehyde on graphene and graphyne was investigated to search high sensitivity sensors for detection of formaldehyde. We have used density functional theory to study the effect of formaldehyde on the electronic properties of graphene and graphyne. It is found that formaldehyde is physisorbed on the graphene and graphyne with small binding energy, large binding distance, and small charge transfer. The calculations also indicate that formaldehyde adsorption modifies the electronic properties of semimetallic graphene, α-graphyne, and β-graphyne and semiconducting γ-graphyne. The graphene and graphyne show semiconducting property in the presence of formaldehyde. The effect of formaldehyde on the electronic properties of graphene and graphyne suggests the potential application of these carbon nanomaterials for formaldehyde detection.

Rediscovering the Schulze-Hardy rule in competitive adsorption to an air-water interface.

Science.gov (United States)

Stenger, Patrick C; Isbell, Stephen G; St Hillaire, Debra; Zasadzinski, Joseph A

2009-09-01

The ratio of divalent to monovalent ion concentration necessary to displace the surface-active protein, albumin, by lung surfactant monolayers and multilayers at an air-water interface scales as 2(-6), the same concentration dependence as the critical flocculation concentration (CFC) for colloids with a high surface potential. Confirming this analogy between competitive adsorption and colloid stability, polymer-induced depletion attraction and electrostatic potentials are additive in their effects; the range of the depletion attraction, twice the polymer radius of gyration, must be greater than the Debye length to have an effect on adsorption.

Trends in reactivity of oxides

DEFF Research Database (Denmark)

Toftelund, Anja

The results in this thesis are based on Density Functional Theory calculations. The catalytic activity of oxides and other compound materials are investigated. It is found that the adsorption energy of the molecules NH2, NH, OH and SH on transition metal nitride, oxide and sulfide surfaces scales......, and I) and OH on a wide range of rutile oxide surfaces. Furthermore, Brønsted-Evans-Polanyi (BEP) relations are found for the adsorption of a large number of molecules (including Cl, Br and I) on transition metal oxides. In these relations the activation energies scale linearly with the dissociative...... chemisorption energies. It turns out that the BEP relation for rutile oxides is almost coinciding with the dissociation line, i.e. no barrier exists for the reactive surfaces. The heterogeneous catalytic oxidation of hydrogen halides (HCl, HBr, and HI) is investigated. A micro-kinetic model is solved...

A procedure to find thermodynamic equilibrium constants for CO2 and CH4 adsorption on activated carbon.

Science.gov (United States)

Trinh, T T; van Erp, T S; Bedeaux, D; Kjelstrup, S; Grande, C A

2015-03-28

Thermodynamic equilibrium for adsorption means that the chemical potential of gas and adsorbed phase are equal. A precise knowledge of the chemical potential is, however, often lacking, because the activity coefficient of the adsorbate is not known. Adsorption isotherms are therefore commonly fitted to ideal models such as the Langmuir, Sips or Henry models. We propose here a new procedure to find the activity coefficient and the equilibrium constant for adsorption which uses the thermodynamic factor. Instead of fitting the data to a model, we calculate the thermodynamic factor and use this to find first the activity coefficient. We show, using published molecular simulation data, how this procedure gives the thermodynamic equilibrium constant and enthalpies of adsorption for CO2(g) on graphite. We also use published experimental data to find similar thermodynamic properties of CO2(g) and of CH4(g) adsorbed on activated carbon. The procedure gives a higher accuracy in the determination of enthalpies of adsorption than ideal models do.

On the mechanism of gas adsorption for pristine, defective and functionalized graphene.

Science.gov (United States)

You, Y; Deng, J; Tan, X; Gorjizadeh, N; Yoshimura, M; Smith, S C; Sahajwalla, V; Joshi, R K

2017-02-22

Defects are no longer deemed an adverse aspect of graphene. Contrarily, they can pave ways of extending the applicability of graphene. Herein, we discuss the effects of three types of defects in graphene including carbon deficiency, adatom (single Fe) dopants and the introduction of functional groups (carbonyl, ether group) on the NO 2 gas adsorption via density functional theory methods. We have observed that introducing Fe on graphene can enhance the NO 2 adsorption process. Adsorption energy calculations suggest that the enhancement in NO 2 adsorption is more profound for Fe-doped mono- and tetra-vacant graphene than that for Fe doped bi- and tri-vacant graphene, which is favourable for NO 2 gas capture applications. The unsaturated carbons in defected graphene as well as the oxygenated functional groups are very active to attract NO 2 molecules. However, though the gas binding strength was not as high as the that found in the Fe-doped graphene structure, the relatively low NO 2 gas adsorption energy is suitable for the practical gas sensors both for gas sensitivity and the sensor recovery rate factor. This theoretical study can potentially be useful for developing adsorption-based applications of graphene.

Investigation kinetics mechanisms of adsorption malachite green onto activated carbon

International Nuclear Information System (INIS)

Onal, Y.; Akmil-Basar, C.; Sarici-Ozdemir, C.

2007-01-01

Lignite was used to prepare activated carbon (T3K618) by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N 2 adsorption isotherm. BET surface area of activated carbon is determined as 1000 m 2 /g. Adsorption capacity of malachite green (MG) onto T3K618 activated carbon was investigated in a batch system by considering the effects of various parameters like initial concentration (100, 150 and 200 mg/L) and temperature (25, 40 and 50 deg. C). The adsorption process was relatively fast and equilibrium was reached after about 20 min for 100, 150 mg/L at all adsorption temperature. Equilibrium time for 200 mg/L was determined as 20 min and 40 min at 298, 313 and 323 K, respectively. Simple mass and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate controlling steps such as external mass transfer, intraparticle diffusion. Pseudo second-order model was found to explain the kinetics of MG adsorption most effectively. It was found that both mass transfer and pore diffusion are important in determining the adsorption rates. The intraparticle diffusion rate constant, external mass transfer coefficient, film and pore diffusion coefficient at various temperatures were evaluated. The activation energy (E a ) was determined as 48.56, 63.16, 67.93 kJ/mol for 100, 150, 200 mg/L, respectively. The Langmiur and Freundlich isotherm were used to describe the adsorption equilibrium studies at different temperatures. Langmiur isotherm shows better fit than Freundlich isotherm in the temperature range studied. The thermodynamic parameters, such as ΔG o , ΔS and ΔH o were calculated. The thermodynamics of dyes-T3K618 system indicates endothermic process

Adsorption of Water and Ethanol in MFI-Type Zeolites

KAUST Repository

Zhang, Ke

2012-06-12

Water and ethanol vapor adsorption phenomena are investigated systematically on a series of MFI-type zeolites: silicalite-1 samples synthesized via both alkaline (OH -) and fluoride (F -) routes, and ZSM-5 samples with different Si/Al ratios as well as different charge-balancing cations. Full isotherms (0.05-0.95 activity) over the range 25-55 °C are presented, and the lowest total water uptake ever reported in the literature is shown for silicalite-1 made via a fluoride-mediated route wherein internal silanol defects are significantly reduced. At a water activity level of 0.95 (35 °C), the total water uptake by silicalite-1 (F -) was found to be 0.263 mmol/g, which was only 12.6%, 9.8%, and 3.3% of the capacity for silicalite-1 (OH -), H-ZSM-5 (Si/Al:140), and H-ZSM-5 (Si/Al:15), respectively, under the same conditions. While water adsorption shows distinct isotherms for different MFI-type zeolites due to the difference in the concentration, distribution, and types of hydrophilic sites, the ethanol adsorption isotherms present relatively comparable results because of the overall organophilic nature of the zeolite framework. Due to the dramatic differences in the sorption behavior with the different sorbate-sorbent pairs, different models are applied to correlate and analyze the sorption isotherms. An adsorption potential theory was used to fit the water adsorption isotherms on all MFI-type zeolite adsorbents studied. The Langmuir model and Sircar\\'s model are applied to describe ethanol adsorption on silicalite-1 and ZSM-5 samples, respectively. An ideal ethanol/water adsorption selectivity (α) was estimated for the fluoride-mediated silicalite-1. At 35 °C, α was estimated to be 36 for a 5 mol % ethanol solution in water increasing to 53 at an ethanol concentration of 1 mol %. The adsorption data demonstrate that silicalite-1 made via the fluoride-mediated route is a promising candidate for ethanol extraction from dilute ethanol-water solutions. © 2012

Adsorption and diffusion of fluids in well-characterized adsorbent materials. Renewal progress report, August 1, 1995 to January 31, 1998

Energy Technology Data Exchange (ETDEWEB)

Gubbins, Keith E.; Cracknell, R.F.; Maddox, M.; Nicholson, D.

1999-08-01

This is an invited review paper describing recent advances in molecular simulation and theory of fluids confined within well-characterized porous materials. Methods and intermolecular potential models are described. This is followed by showing results for several examples, including supercritical methane adsorption in carbons, adsorption and diffusion of argon in VPI-5, adsorption of argon in silicalite-1, nitrogen adsorption in MCM-41, and adsorption of argon and nitrogen in carbon nanotubes.

Adsorption

Directory of Open Access Journals (Sweden)

Sushmita Banerjee

2017-05-01

Full Text Available Application of saw dust for the removal of an anionic dye, tartrazine, from aqueous solutions has been investigated. The experiments were carried out in batch mode. Effect of the parameters such as pH, initial dye concentration and temperature on the removal of the dye was studied. Equilibrium was achieved in 70 min. Maximum adsorption of dye was achieved at pH 3. Removal percent was found to be dependent on the initial concentration of dye solution, and maximum removal was found to be 97% at 1 mg/L of tartrazine. The removal increases from 71% to 97% when the initial concentration of dye solution decreases from 15 mg/L to 1 mg/L. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The (Langmuir adsorption capacity of the adsorbent is found to be 4.71 mg/g at 318 K. Kinetic modeling of the process of removal was carried out and the process of removal was found to follow a pseudo second order model and the value of rate constant for adsorption process was calculated as 2.7 × 10−3 g mg−1 min−1 at 318 K. The thermodynamic parameters such as change in free energy (ΔG°, enthalpy (ΔH° and entropy (ΔS° were determined and the negative values of ΔG° indicated that the process of removal was spontaneous at all values of temperatures. Further, the values of ΔH° indicated the endothermic nature of the process of removal.

A study of uranium adsorption to single-crystal tungsten

Energy Technology Data Exchange (ETDEWEB)

Samin, Adib; Hastings, Aaron; Zhang, Jinsuo, E-mail: jzhang@osu.edu

2015-12-15

In this study we explore the adsorption of uranium to the (110) plane of tungsten. Potential functions were constructed to describe the interaction of adsorbed uranium atoms with the tungsten surface and the lateral interaction between adsorbed uranium atoms. Next, the behavior of the uranium adlayer under different conditions was studied through a Monte Carlo simulation of the grand canonical Hamiltonian in an off-lattice model. Our results are consistent with available studies in the literature. The simulation results indicate that the temperature and dipole–dipole interactions play an important role in governing the adsorption process.

A study of uranium adsorption to single-crystal tungsten

International Nuclear Information System (INIS)

Samin, Adib; Hastings, Aaron; Zhang, Jinsuo

2015-01-01

In this study we explore the adsorption of uranium to the (110) plane of tungsten. Potential functions were constructed to describe the interaction of adsorbed uranium atoms with the tungsten surface and the lateral interaction between adsorbed uranium atoms. Next, the behavior of the uranium adlayer under different conditions was studied through a Monte Carlo simulation of the grand canonical Hamiltonian in an off-lattice model. Our results are consistent with available studies in the literature. The simulation results indicate that the temperature and dipole–dipole interactions play an important role in governing the adsorption process.

Characteristics of Heavy Metals Adsorption Cu, Pb and Cd Using Synthetics Zeolite Zsm-5

OpenAIRE

Priyadi,; Iskandar,; Suwardi,; Mukti, Rino Rakhmata

2015-01-01

It is generally known that zeolite has potential for heavy metal adsorption. The objectives of this study were to synthesize and characterize zeolite ZSM-5 and to figure out the adsorption capacity of zeolite ZSM-5 for heavy metals of Cu2+, Pb2+ and Cd2+. Characterization of zeolite ZSM-5 included some variables i.e. crystal structure (XRD), morphology (SEM), specific surface area and total pore volume (N2 physisorption). Adsorption capacity of zeolite ZSM-5 was analysed using a batch system...

Effect of Micellization on the Adsorption Kinetics of Polymeric Surfactants to the Solid/Water Interface

Science.gov (United States)

Toomey, Ryan; Tirrell, Matthew

2002-03-01

We have studied the adsorption kinetics of two classes of hydrophobic/ionic diblock copolymer surfactants in aqueous environments to understand the role that micellization plays in the adsorption process. The two systems studied were poly(t-butyl styrene)-block-poly(styrene sulfonate) (PtBS-b-PSS) and polystyrene-block-poly(acrylic acid) (PS-b-PAA). It is found that by changing the hydrophobicity of the adsorbing surface, micelle adsorption can be turned on or off. When micelle adsorption occurs, the initial adsorption rate is always slower than the supply rate of micelles to the surface, indicating “reaction-limited” adsorption. Since these micelles have essentially frozen cores, the adsorption cannot be explained by the release of unimers from the micelles. Rather, micelles directly adsorb, and they have to overcome the potential barrier imposed by their corona. Due to micellization, the adsorption rate can also be a complex function of ionic strength. A regime was found where the initial adsorption rate decreased with increasing ionic strength. This anomaly can be explained by the onset of micellization. As the salt concentration is increased, more micelles are formed. However micelles adsorb roughly an order of magnitude slower than free chains. Therefore, if increasing the ionic strength produces more micelles, the adsorption rate will simultaneously decrease.

Adsorption of amylase enzyme on ultrafiltration membranes

DEFF Research Database (Denmark)

Beier, Søren; Enevoldsen, Ann Dorrit; Kontogeorgis, Georgios

2007-01-01

A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of an amylase-F has been measured on two different ultrafiltration membranes, both with a cut-off value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface......-modified PVDF membrane). The adsorption follows the Langmuir adsorption theory. Thus, the static adsorption consists of monolayer coverage. The static adsorption is expressed both as a permeability drop and an adsorption resistance. From the adsorption isotherms the maximum static permeability drops...... and the maximum static adsorption resistances are determined. The maximum static permeability drop for the hydrophobic PES membrane is 75 % and the maximum static adsorption resistance is 0.014 m2hbar/L. The maximum static permeability drop for the hydrophilic surface-modified PVDF membrane (ETNA10PP) is 23...

Adsorptive removal of arsenic by novel iron/olivine composite: Insights into preparation and adsorption process by response surface methodology and artificial neural network.

Science.gov (United States)

Ghosal, Partha S; Kattil, Krishna V; Yadav, Manoj K; Gupta, Ashok K

2018-03-01

Olivine, a low-cost natural material, impregnated with iron is introduced in the adsorptive removal of arsenic. A wet impregnation method and subsequent calcination were employed for the preparation of iron/olivine composite. The major preparation process parameter, viz., iron loading and calcination temperature were optimized through the response surface methodology coupled with a factorial design. A significant variation of adsorption capacity of arsenic (measured as total arsenic), i.e., 63.15 to 310.85 mg/kg for arsenite [As(III) T ] and 76.46 to 329.72 mg/kg for arsenate [As(V) T ] was observed, which exhibited the significant effect of the preparation process parameters on the adsorption potential. The iron loading delineated the optima at central points, whereas a monotonous decreasing trend of adsorption capacity for both the As(III) T and As(V) T was observed with the increasing calcination temperature. The variation of adsorption capacity with the increased iron loading is more at lower calcination temperature showing the interactive effect between the factors. The adsorbent prepared at the optimized condition of iron loading and calcination temperature, i.e., 10% and 200 °C, effectively removed the As(III) T and As(V) T by more than 96 and 99%, respectively. The material characterization of the adsorbent showed the formation of the iron compound in the olivine and increase in specific surface area to the tune of 10 multifold compared to the base material, which is conducive to the enhancement of the adsorption capacity. An artificial neural network was applied for the multivariate optimization of the adsorption process from the experimental data of the univariate optimization study and the optimized model showed low values of error functions and high R 2 values of more than 0.99 for As(III) T and As(V) T . The adsorption isotherm and kinetics followed Langmuir model and pseudo second order model, respectively demonstrating the chemisorption in this

Modelling phosphate adsorption to the soil: Application of the non-ideal competitive adsorption model

International Nuclear Information System (INIS)

Abou Nohra, Joumana S.; Madramootoo, Chandra A.; Hendershot, William H.

2007-01-01

Phosphorus (P) transport in subsurface runoff has increased despite the limited mobility of P in soils. This study investigated the ability of the non-ideal competitive adsorption (NICA) model to describe phosphate (PO 4 ) adsorption for soils in southern Quebec (Canada). We measured the surface charge and PO 4 adsorption capacity for 11 agricultural soils. Using the experimental data and a nonlinear fitting function, we derived the NICA model parameters. We found that the NICA model described accurately the surface charge of these soils with a mean R 2 > 0.99, and described the adsorption data with a mean R 2 = 0.96. We also found that the variable surface charge was distributed over the two binding sites with the low pH sites demonstrating a stronger binding energy for hydroxyl and PO 4 ions. We established that the NICA model is able to describe P adsorption for the soils considered in this study. - The NICA model accurately described the adsorption of phosphate to some southern Quebec soils

Removal of Remazol brilliant violet textile dye by adsorption using rice hulls

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Geyse Adriana Correa; Silva, Domingos Sergio Araujo; Santos, Clayane Carvalho dos; Bezerra, Cicero Wellington Brito; Tanaka, Auro Atsushi; Santana, Sirlane Aparecida Abreu, E-mail: cwb.bezerra@ufma.br [Universidade Federal do Maranhao, (UFMA), Sao Luis (Brazil); Vieira, Adriana Pires [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil)

2017-01-15

The release of industrial effluents into the environment causes widespread contamination of aquatic systems. Adsorption is seen as one of the most promising treatment processes, and lignocellulosic materials have gained prominence as adsorbents. This study investigates the potential of rice hulls, either in natura or treated with nitric acid, as adsorbents for removal of the dye. The adsorbents were characterized by infrared spectroscopy, solid state {sup 13}C-NMR, thermogravimetric analysis, and pH at point of zero charge. The dye adsorption experiments were carried out in batch mode, using different experimental conditions. The kinetic adsorption data could be fitted using the model of Elovich. The Freundlich model provided the best fit to the isothermal data. The thermodynamic parameters confirmed the spontaneity of the adsorption process. These adsorbents offer an alternative for dye removal, with advantages including biomass availability and low cost. (author)

Extraction or adsorption? Voltammetric assessment of protamine transfer at ionophore-based polymeric membranes.

Science.gov (United States)

Garada, Mohammed B; Kabagambe, Benjamin; Amemiya, Shigeru

2015-01-01

Cation-exchange extraction of polypeptide protamine from water into an ionophore-based polymeric membrane has been hypothesized as the origin of a potentiometric sensor response to this important heparin antidote. Here, we apply ion-transfer voltammetry not only to confirm protamine extraction into ionophore-doped polymeric membranes but also to reveal protamine adsorption at the membrane/water interface. Protamine adsorption is thermodynamically more favorable than protamine extraction as shown by cyclic voltammetry at plasticized poly(vinyl chloride) membranes containing dinonylnaphthalenesulfonate as a protamine-selective ionophore. Reversible adsorption of protamine at low concentrations down to 0.038 μg/mL is demonstrated by stripping voltammetry. Adsorptive preconcentration of protamine at the membrane/water interface is quantitatively modeled by using the Frumkin adsorption isotherm. We apply this model to ensure that stripping voltammograms are based on desorption of all protamine molecules that are transferred across the interface during a preconcentration step. In comparison to adsorption, voltammetric extraction of protamine requires ∼0.2 V more negative potentials, where a potentiometric super-Nernstian response to protamine is also observed. This agreement confirms that the potentiometric protamine response is based on protamine extraction. The voltammetrically reversible protamine extraction results in an apparently irreversible potentiometric response to protamine because back-extraction of protamine from the membrane extremely slows down at the mixed potential based on cation-exchange extraction of protamine. Significantly, this study demonstrates the advantages of ion-transfer voltammetry over potentiometry to quantitatively and mechanistically assess protamine transfer at ionophore-based polymeric membranes as foundation for reversible, selective, and sensitive detection of protamine.

Numerical evaluation of Cs adsorption in PB column by extended Langmuir formula and one-dimensional adsorption model

International Nuclear Information System (INIS)

Hiroshi Ogawa; Akiko Kitajima; Hisashi Tanaka; Tohru Kawamoto

2015-01-01

Adsorption property of granulated Prussian blue adsorbent on radioactive cesium was evaluated for efficient decontamination in Fukushima area. The adsorbent was found to show an inflective adsorption isotherm, which was expressed by extended Langmuir formula with three adsorption sites. Adsorption speeds of each site were evaluated by time-dependent batch experiment. The simulation using derived parameters and one-dimensional adsorption model successfully reproduced the experimental data of cesium decontamination by small and large columns. (author)

Valorization of Toxic Weed Lantana camara L. Biomass for Adsorptive Removal of Lead

Directory of Open Access Journals (Sweden)

Vipin Kumar Saini

2017-01-01

Full Text Available Valorization of Lantana camara L., which is a recognized invasive plant, as a potential source of activated carbon is proposed in this study. Its stem and leaf have been utilized for the preparation of activated carbon (ACL and ACS by following acid-impregnation technique, followed by thermal treatment. The developed activated carbon samples were characterized for their structural and surface related properties by low-temperature nitrogen adsorption isotherm, SEM techniques, and pHPZC method. The samples show reasonable high surface area and pore volume; nonetheless, these properties are higher in case of ACL as compraed to ACS. Both of these samples developed negative charge on their surface due to acid treatment that resulted in an increase in adsorption at pH > 5. The batch adsorption studies on these samples shows the Pb(II ion adsorption capacities of ACL and ACS were 36.01 and 32.24 mg·g−1, respectively, at 25°C. The kinetics of adsorption with both the sample systems follow the pseudo-second-order model, whereas the experimental equilibrium isotherm data of ACL and ACS were explained by Freundlich and Langmuir models, respectively. For these samples, the HCl shows maximum desorption with which the recycling test on these samples shows that ACS has better recycling potential over ACL samples.

Protein Adsorption in Three Dimensions

Science.gov (United States)

Vogler, Erwin A.

2011-01-01

Recent experimental and theoretical work clarifying the physical chemistry of blood-protein adsorption from aqueous-buffer solution to various kinds of surfaces is reviewed and interpreted within the context of biomaterial applications, especially toward development of cardiovascular biomaterials. The importance of this subject in biomaterials surface science is emphasized by reducing the “protein-adsorption problem” to three core questions that require quantitative answer. An overview of the protein-adsorption literature identifies some of the sources of inconsistency among many investigators participating in more than five decades of focused research. A tutorial on the fundamental biophysical chemistry of protein adsorption sets the stage for a detailed discussion of the kinetics and thermodynamics of protein adsorption, including adsorption competition between two proteins for the same adsorbent immersed in a binary-protein mixture. Both kinetics and steady-state adsorption can be rationalized using a single interpretive paradigm asserting that protein molecules partition from solution into a three-dimensional (3D) interphase separating bulk solution from the physical-adsorbent surface. Adsorbed protein collects in one-or-more adsorbed layers, depending on protein size, solution concentration, and adsorbent surface energy (water wettability). The adsorption process begins with the hydration of an adsorbent surface brought into contact with an aqueous-protein solution. Surface hydration reactions instantaneously form a thin, pseudo-2D interface between the adsorbent and protein solution. Protein molecules rapidly diffuse into this newly-formed interface, creating a truly 3D interphase that inflates with arriving proteins and fills to capacity within milliseconds at mg/mL bulk-solution concentrations CB. This inflated interphase subsequently undergoes time-dependent (minutes-to-hours) decrease in volume VI by expulsion of either-or-both interphase water and

Development of adsorptive membranes by confinement of activated biochar into electrospun nanofibers

Directory of Open Access Journals (Sweden)

Mehrdad Taheran

2016-11-01

Full Text Available Adsorptive membranes have many applications in removal of contaminants, such as heavy metals and organic contaminants from water. Recently, increasing concentrations of pharmaceutically active compounds, especially antibiotics, such as chlortetracycline in water and wastewater sources has raised concerns about their potentially adverse impacts on environment and human health. In this study, a series of polyacrylonitrile (PAN/activated biochar nanofibrous membranes (NFMs with different loadings of biochar (0–2%, w/w were fabricated using electrospinning. The morphology and structure of fabricated membranes was investigated by scanning electron microscopy, Fourier transform infrared and thermogravimetric analysis. The results showed that at 1.5% of biochar loading, the surface area reached the maximum value of 12.4 m2/g and beyond this loading value, agglomeration of particles inhibited fine interaction with nanofibrous matrix. Also, the adsorption tests using chlortetracycline showed that, under environmentally relevant concentrations, the fabricated adsorptive NFMs had a potential for removal of these types of emerging contaminants from water and wastewaters.

A modified Poisson-Boltzmann equation applied to protein adsorption.

Science.gov (United States)

Gama, Marlon de Souza; Santos, Mirella Simões; Lima, Eduardo Rocha de Almeida; Tavares, Frederico Wanderley; Barreto, Amaro Gomes Barreto

2018-01-05

Ion-exchange chromatography has been widely used as a standard process in purification and analysis of protein, based on the electrostatic interaction between the protein and the stationary phase. Through the years, several approaches are used to improve the thermodynamic description of colloidal particle-surface interaction systems, however there are still a lot of gaps specifically when describing the behavior of protein adsorption. Here, we present an improved methodology for predicting the adsorption equilibrium constant by solving the modified Poisson-Boltzmann (PB) equation in bispherical coordinates. By including dispersion interactions between ions and protein, and between ions and surface, the modified PB equation used can describe the Hofmeister effects. We solve the modified Poisson-Boltzmann equation to calculate the protein-surface potential of mean force, treated as spherical colloid-plate system, as a function of process variables. From the potential of mean force, the Henry constants of adsorption, for different proteins and surfaces, are calculated as a function of pH, salt concentration, salt type, and temperature. The obtained Henry constants are compared with experimental data for several isotherms showing excellent agreement. We have also performed a sensitivity analysis to verify the behavior of different kind of salts and the Hofmeister effects. Copyright © 2017 Elsevier B.V. All rights reserved.

Copper adsorption in tropical oxisols

Directory of Open Access Journals (Sweden)

Silveira Maria Lucia Azevedo

2003-01-01

Full Text Available Cu adsorption, at concentrations between 0 to 800 mg L-1, was evaluated in surface and subsurface samples of three Brazilian soils: a heavy clayey-textured Rhodic Hapludalf (RH, a heavy clayey-textured Anionic ''Rhodic'' Acrudox (RA and a medium-textured Anionic ''Xanthic'' Acrudox (XA. After adsorption, two consecutive extractions were performed to the samples which received 100 mg L-1 copper. Surface samples adsorbed higher amounts of Cu than the subsurface, and exhibited lower Cu removed after the extractions, reinforcing the influence of the organic matter in the reactions. Cu adsorption was significant in the subsurface horizons of the Oxisols, despite the positive balance of charge, demonstrating the existence of mechanisms for specific adsorption, mainly related to the predominance of iron and aluminum oxides in the mineral fractions. In these samples, Cu was easily removed from the adsorption sites. RH demonstrated a higher capacity for the Cu adsorption in both horizons.

Relationship between carbon microstructure, adsorption energy and hydrogen adsorption capacity at different temperatures

International Nuclear Information System (INIS)

Jagiello, J.; Thommes, M.

2005-01-01

Various microporous materials such as activated carbons, nano-tubes, synthetic micro-porous carbons as well as metal organic framework materials are being considered for hydrogen storage applications by means of physical adsorption. To develop materials of practical significance for hydrogen storage it is important to understand the relationships between pore sizes, adsorption energies and adsorption capacities. The pore size distribution (PSD) characterization is traditionally obtained from the analysis of nitrogen adsorption isotherms measured at 77 K. However, a portion of the pores accessible to H 2 may not be accessible to N 2 at this temperature. Therefore, it was recently proposed to use the DFT analysis of H 2 adsorption isotherms to characterize pore structure of materials considered for hydrogen storage applications [1]. In present work, adsorption isotherms of H 2 and N 2 at cryogenic temperatures are used for the characterization of carbon materials. Adsorption measurements were performed with Autosorb 1 MP [Quantachrome Instruments, Boynton Beach, Florida, USA]. As an example, Fig 1 compares PSDs calculated for the activated carbon sample (F400, Calgon Carbon) using combined H 2 and N 2 data, and using N 2 isotherm only. The nitrogen derived PSD does not include certain amount of micro-pores which are accessible to H 2 but not to N 2 molecules. Obviously, the difference in the calculated PSDs by the two methods will depend on the actual content of small micro-pores in a given sample. Carbon adsorption properties can also be characterized by the isosteric heat of adsorption, Qst, related to the adsorption energy and dependent on the carbon pore/surface structure. Fig 2 shows Qst data calculated using the Clausius-Clapeyron equation from H 2 isotherms measured at 77 K and 87 K for the carbon molecular sieve CMS 5A (Takeda), oxidized single wall nano-tubes (SWNT) [2], and graphitized carbon black (Supelco). The Qst values decrease with increasing pore

Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

Science.gov (United States)

Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

2014-01-01

Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

Adsorption refrigeration technology theory and application

CERN Document Server

Wang, Ruzhu; Wu, Jingyi

2014-01-01

Gives readers a detailed understanding of adsorption refrigeration technology, with a focus on practical applications and environmental concerns Systematically covering the technology of adsorption refrigeration, this book provides readers with a technical understanding of the topic as well as detailed information on the state-of-the-art from leading researchers in the field. Introducing readers to background on the development of adsorption refrigeration, the authors also cover the development of adsorbents, various thermodynamic theories, the design of adsorption systems and adsorption refri

Adsorption Dynamics and Self-Assembled L-cysteine on Au(100)

DEFF Research Database (Denmark)

Engelbrekt, Christian; Nazmutdinov, Renat R.; Yan, Jiawei

As the only amino acid with a functional thiol group, L - cysteine offers a strong perspective both for binding to gold and other metals, and for gentle immobilization of biomolecules. Binding to single - crystal, atomically planar surfaces offers the additional perspective that bound L - cysteine...... can be structurally mapped at the single - molecule level . In this work, we have followed the adsorption of L - cysteine on single - crystal Au(100) by measuring the electrode potential dynamics during the adsorption process. In situ STM revealed the structure of the self - assembled ordered layers...

Adsorption of lithium-lanthanum films on the (100) tungsten face

International Nuclear Information System (INIS)

Gupalo, M.S.; Smereka, T.P.; Babkin, G.V.; Palyukh, B.M.

1982-01-01

The method of contact potential difference is used to investigate combined adsorption of lithium-lanthanum on the (100) tungsten face. The data on work functions and thermal stability of mixed lithium-lanthanum films are obtained. The presence of lanthanum on the W(100) surface leads to appearance of minimum of work functions unobserved for the Li-W(100) system, minimum work functions and optimum lithium concentration in a mixed film are decreased at initial lanthanum coating increase. The presence of lanthanum on the W(100) face leads to lithium adsorption heat decrease

Equilibrium and heat of adsorption of diethyl phthalate on heterogeneous adsorbents

Energy Technology Data Exchange (ETDEWEB)

Zhang, W.M.; Xu, Z.W.; Pan, B.C.; Hong, C.H.; Jia, K.; Jiang, P.J.; Zhang, Q.J.; Pan, B.J. [Nanjing University, Nanjing (China)

2008-09-15

Removal of phthalate esters from water has been of considerable concern recently. In the present study, the adsorptive removal performance of diethyl phthalate (DEP) from water was investigated with the aminated polystyrene resin (NDA-101) and oxidized polystyrene resin (NDA-702). In addition, the commercial homogeneous polystyrene resin (XAD-4) and acrylic ester resin (Amberlite XAD-7) as well as coal-based granular activated carbon (AC-750) were chosen for comparison. The corresponding equilibrium isotherms are well described by the Freundlich equation and the adsorption capacities for DEP followed the order NDA-702 > NDA-101 > AC-750 > XAD-4 > XAD-7. Analysis of adsorption mechanisms suggested that these adsorbents spontaneously adsorb DEP molecules driven mainly by enthalpy change, and the adsorption process was derived by multiple adsorbent-adsorbate interactions such as hydrogen bonding, {pi}-{pi} stacking, and micropore filling. The information related to the adsorbent surface heterogeneity and the adsorbate-adsorbate interaction was obtained by Do's model. All the results indicate that heterogeneous resins NDA-702 and NDA-101 have excellent potential as an adsorption material for the removal of DEP from the contaminated water.

Surface Complexation Modeling of Fluoride Adsorption by Soil and the Role of Dissolved Aluminum on Adsorption

Science.gov (United States)

Padhi, S.; Tokunaga, T.

2017-12-01

Adsorption of fluoride (F) on soil can control the mobility of F and subsequent contamination of groundwater. Hence, accurate evaluation of adsorption equilibrium is a prerequisite for understanding transport and fate of F in the subsurface. While there have been studies for the adsorption behavior of F with respect to single mineral constituents based on surface complexation models (SCM), F adsorption to natural soil in the presence of complexing agents needs much investigation. We evaluated the adsorption processes of F on a natural granitic soil from Tsukuba, Japan, as a function of initial F concentration, ionic strength, and initial pH. A SCM was developed to model F adsorption behavior. Four possible surface complexation reactions were postulated with and without including dissolved aluminum (Al) and Al-F complex sorption. Decrease in F adsorption with the increase in initial pH was observed in between the initial pH range of 4 to 9, and a decrease in the rate of the reduction of adsorbed F with respect to the increase in the initial pH was observed in the initial pH range of 5 to 7. Ionic strength variation in the range of 0 to 100mM had insignificant effect on F removal. Changes in solution pH were observed by comparing the solution before and after F adsorption experiments. At acidic pH, the solution pH increased, whereas at alkaline pH, the solution pH decreased after equilibrium. The SCM including dissolved Al and the adsorption of Al-F complex can simulate the experimental results quite successfully. Also, including dissolved Al and the adsorption of Al-F complex to the model explained the change in solution pH after F adsorption.

Binary gas mixture adsorption-induced deformation of microporous carbons by Monte Carlo simulation.

Science.gov (United States)

Cornette, Valeria; de Oliveira, J C Alexandre; Yelpo, Víctor; Azevedo, Diana; López, Raúl H

2018-07-15

Considering the thermodynamic grand potential for more than one adsorbate in an isothermal system, we generalize the model of adsorption-induced deformation of microporous carbons developed by Kowalczyk et al. [1]. We report a comprehensive study of the effects of adsorption-induced deformation of carbonaceous amorphous porous materials due to adsorption of carbon dioxide, methane and their mixtures. The adsorption process is simulated by using the Grand Canonical Monte Carlo (GCMC) method and the calculations are then used to analyze experimental isotherms for the pure gases and mixtures with different molar fraction in the gas phase. The pore size distribution determined from an experimental isotherm is used for predicting the adsorption-induced deformation of both pure gases and their mixtures. The volumetric strain (ε) predictions from the GCMC method are compared against relevant experiments with good agreement found in the cases of pure gases. Copyright © 2018 Elsevier Inc. All rights reserved.

Environmentally benign working pairs for adsorption refrigeration

International Nuclear Information System (INIS)

Cui Qun; Tao Gang; Chen Haijun; Guo Xinyue; Yao Huqing

2005-01-01

This paper begins from adsorption working pairs: water and ethanol were selected as refrigerants; 13x molecular sieve, silica gel, activated carbon, adsorbent NA and NB, proposed by authors, were selected as adsorbents, and the performance of adsorption working pairs in adsorption refrigeration cycle was studied. The adsorption isotherms of adsorbents (NA and NB) were obtained by high-vacuum gravimetric method. Desorption properties of adsorbents were analyzed and compared by thermal analysis method. The performance of adsorption refrigeration was studied on simulation device of adsorption refrigeration cycle. After presentation of adsorption isotherms, the thermodynamic performance for their use in adsorption refrigeration system was calculated. The results show: (1) the maximum adsorption capacity of water on adsorbent NA reaches 0.7 kg/kg, and the maximum adsorption capacity of ethanol on adsorbent NB is 0.68 kg/kg, which is three times that of ethanol on activated carbon, (2) the refrigeration capacity of NA-water working pair is 922 kJ/kg, the refrigeration capacity of NB-ethanol is 2.4 times that of activated carbon-methanol, (3) as environmental friendly and no public hazard adsorption working pair, NA-H 2 O and NB-ethanol can substitute activated carbon-methanol in adsorption refrigeration system using low-grade heat source

Dye and its removal from aqueous solution by adsorption: a review.

Science.gov (United States)

Yagub, Mustafa T; Sen, Tushar Kanti; Afroze, Sharmeen; Ang, H M

2014-07-01

In this review article the authors presented up to-date development on the application of adsorption in the removal of dyes from aqueous solution. This review article provides extensive literature information about dyes, its classification and toxicity, various treatment methods, and dye adsorption characteristics by various adsorbents. One of the objectives of this review article is to organise the scattered available information on various aspects on a wide range of potentially effective adsorbents in the removal of dyes. Therefore, an extensive list of various adsorbents such as natural materials, waste materials from industry, agricultural by-products, and biomass based activated carbon in the removal of various dyes has been compiled here. Dye bearing waste treatment by adsorption using low cost alternative adsorbent is a demanding area as it has double benefits i.e. water treatment and waste management. Further, activated carbon from biomass has the advantage of offering an effected low cost replacement for non-renewable coal based granular activated carbon provided that they have similar or better adsorption on efficiency. The effectiveness of various adsorbents under different physico-chemical process parameters and their comparative adsorption capacity towards dye adsorption has also been presented. This review paper also includes the affective adsorption factors of dye such as solution pH, initial dye concentration, adsorbent dosage, and temperature. The applicability of various adsorption kinetic models and isotherm models for dye removal by wide range of adsorbents is also reported here. Conclusions have been drawn from the literature reviewed and few suggestions for future research are proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of softening precipitate composition and surface characteristics on natural organic matter adsorption.

Science.gov (United States)

Russell, Caroline G; Lawler, Desmond F; Speitel, Gerald E; Katz, Lynn E

2009-10-15

Natural organic matter (NOM) removal during water softening is thought to occur through adsorption onto or coprecipitation with calcium and magnesium solids. However, details of precipitate composition and surface chemistry and subsequent interactions with NOM are relatively unknown. In this study, zeta potentiometry analyses of precipitates formed from inorganic solutions under varying conditions (e.g., Ca-only, Mg-only, Ca + Mg, increasing lime or NaOH dose) indicated that both CaCO3 and Mg(OH)2 were positively charged at higher lime (Ca(OH)2) and NaOH doses (associated with pH values above 11.5), potentially yielding a greater affinity for adsorbing negatively charged organic molecules. Environmental scanning electron microscopy (ESEM) images of CaCO3 solids illustrated the rhombohedral shape characteristic of calcite. In the presence of increasing concentrations of magnesium, the CaCO3 rhombs shifted to more elongated crystals. The CaCO3 solids also exhibited increasingly positive surface charge from Mg incorporation into the crystal lattice, potentially creating more favorable conditions for adsorption of organic matter. NOM adsorption experiments using humic substances extracted from Lake Austin and Missouri River water elucidated the role of surface charge and surface area on adsorption.

Weakly-bound adsorption states and low-temperature adsorption kinetiks of oxygen on tungsten (100) and (110) faces

International Nuclear Information System (INIS)

Zhukov, V.V.; Osovskij, V.D.; Ptushnikov, Yu.G.; Sukretnyj, V.G.; Chujkov, B.A.

1986-01-01

A molecular beam technique with an effusion source operating at T=200 K is used to study the adsorption interaction of oxygen with W(100) and (110) faces in the range of the simple temperatures from 5 to 340 K. Three weakly-bound adsorption states of oxygen are detected corresponding to adsorption in the second, third and forth monolayer. These states are characterized by adsorption energies of 0.13, 0.08 and 0.07 eV and desorption temperatures of 45, 27 and 25 K, respectively. The kinetics of filling of these states is almost similar for both faces, whereas the adsorption kinetics in the first monolayer is essentially different. A dissociative nature of adsorption at T >or approx. 5 K and a jump migration mechanism of the admolecules in the precursor state to the stationary adsorption sites are suggested

The adsorption potential and recovery of thallium using green micro-algae from eutrophic water sources.

Science.gov (United States)

Birungi, Z S; Chirwa, E M N

2015-12-15

Thallium (Tl) is a highly volatile and toxic heavy metal regarded to cause pollution even at very low concentrations of several parts per million. Despite the extremely high risk of Tl in the environment, limited information on removal/recovery exists. The study focussed on the use of green algae to determine the sorption potential and recovery of Tl. From the study, removal efficiency was achieved at 100% for lower concentrations of ≥150 mg/L of Tl. At higher concentrations in a range of 250-500 mg/L, the performance of algae was still higher with sorption capacity (qmax) between 830 and 1000 mg/g. Generally, Chlorella vulgaris was the best adsorbent with a high qmax and lower affinity of 1000 mg/g and 1.11 L/g, respectively. When compared to other studies on Tl adsorption, the tested algae showed a better qmax than most adsorbents. The kinetic studies showed better correlation co-efficient of ≤0.99 for Pseudo-second order model than the first order model. Recovery was achieved highest for C. vulgaris using nitric acid at 93.3%. The strongest functional groups responsible for Tl binding on the algal cell wall were carboxyl and phenols. Green algae from freshwater bodies showed significant potential for Tl removal/recovery from industrial wastewater. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradation and adsorption of pesticides in compost-based biomixtures as potential substrates for biobeds in southern Europe.

Science.gov (United States)

Karanasios, Evangelos; Tsiropoulos, Nikolaos G; Karpouzas, Dimitrios G; Ehaliotis, Constantinos

2010-08-25

Biobeds have been used in northern Europe for minimizing point source contamination of water resources by pesticides. However, little is known regarding their use in southern Europe where edaphoclimatic conditions and agriculture practices significantly differ. A first step toward their adaptation in southern Europe is the use of low-cost and easily available substrates as biomixture components. This study investigated the possibility of replacing peat with agricultural composts in the biomixture. Five composts from local substrates including olive leaves, cotton crop residues, cotton seeds, spent mushroom substrate, and commercial sea wrack were mixed with topsoil and straw (1:1:2). Degradation of a mixture of pesticides (dimethoate, indoxacarb, buprofezin, terbuthylazine, metribuzin, metalaxyl-M, iprodione, azoxystrobin) at two dose rates was tested in the compost biomixtures (BX), in corresponding peat biomixtures (OBX), and in soil. Adsorption-desorption of selected pesticides were also studied. Pesticide residues were determined by gas chromatography with nitrogen-phosphorus detector, except indoxacarb, which was determined with a microelectron capture detector. Overall, BX degraded the studied pesticides at rates markedly higher than those observed in soil and OBX, in which the slowest degradation rates were evident. Overall, the olive leaf compost biomixture showed the highest degradation capacity. Adsorption studies showed that OBX and BX had higher adsorption affinity compared to soil. Desorption experiments revealed that pesticide adsorption in biomixtures was not entirely reversible. The results suggest that substitution of peat with local composts will lead to optimization of the biobed system for use in Mediterranean countries.

Adsorptive removal of Auramine-O: Kinetic and equilibrium study

International Nuclear Information System (INIS)

Mall, Indra Deo; Srivastava, Vimal Chandra; Agarwal, Nitin Kumar

2007-01-01

Present study deals with the adsorption of Auramine-O (AO) dye by bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH 0 ), contact time, adsorbent dose and initial concentration (C 0 ) for the removal of AO. Optimum conditions for AO removal were found to be pH 0 ∼ 7.0 and equilibrium time ∼30 min for BFA and ∼120 min for activated carbons. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2 g/l, respectively. Adsorption of AO followed pseudo-second order kinetics with the initial sorption rate for adsorption on BFA being the highest followed by those on ACL and ACC. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Equilibrium isotherms for the adsorption of AO on BFA, ACC and ACL were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin isotherm equations using linear correlation coefficient. Langmuir isotherm gave the best correlation of adsorption for all the adsorbents studied. Thermodynamic study showed that adsorption of AO on ACC (with a more negative Gibbs free energy value) is more favoured. BFA which was used without any pretreatment showed high surface area, pore volume and pore size exhibiting its potential to be used as an adsorbent for the removal of AO

FY-2015 Methyl Iodide Deep-Bed Adsorption Test Report

International Nuclear Information System (INIS)

Soelberg, Nicholas Ray; Watson, Tony Leroy

2015-01-01

Nuclear fission produces fission and activation products, including iodine-129, which could evolve into used fuel reprocessing facility off-gas systems, and could require off-gas control to limit air emissions to levels within acceptable emission limits. Deep-bed methyl iodide adsorption testing has continued in Fiscal Year 2015 according to a multi-laboratory methyl iodide adsorption test plan. Updates to the deep-bed test system have also been performed to enable the inclusion of evaporated HNO 3 and increased NO 2 concentrations in future tests. This report summarizes the result of those activities. Test results showed that iodine adsorption from gaseous methyl iodide using reduced silver zeolite (AgZ) resulted in initial iodine decontamination factors (DFs, ratios of uncontrolled and controlled total iodine levels) under 1,000 for the conditions of the long-duration test performed this year (45 ppm CH3I, 1,000 ppm each NO and NO 2 , very low H 2 O levels [3 ppm] in balance air). The mass transfer zone depth exceeded the cumulative 5-inch depth of 4 bed segments, which is deeper than the 2-4 inch depth estimated for the mass transfer zone for adsorbing I 2 using AgZ in prior deep-bed tests. The maximum iodine adsorption capacity for the AgZ under the conditions of this test was 6.2% (6.2 g adsorbed I per 100 g sorbent). The maximum Ag utilization was 51%. Additional deep-bed testing and analyses are recommended to (a) expand the data base for methyl iodide adsorption and (b) provide more data for evaluating organic iodide reactions and reaction byproducts for different potential adsorption conditions.

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

Energy Technology Data Exchange (ETDEWEB)

Darwish, Ahmed A. [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Nuclear and Radiation Engineering, Faculty of Engineering, Alexandria University, Alexandria (Egypt); Fadlallah, Mohamed M. [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Physics, Faculty of Science, Benha University, Benha (Egypt); Badawi, Ashraf [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Maarouf, Ahmed A., E-mail: ahmed.maarouf@egnc.gov.eg [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Egypt Nanotechnology Center & Department of Physics, Faculty of Science, Cairo University, Giza 12613 (Egypt)

2016-07-30

Highlights: • Doping boron nitride sheets with aluminum or gallium atoms significantly enhances their molecular adsorption properties. • Adsorption of glucose or glucosamine on Al- and Ga-doped boron nitride sheets changes the band gap. • Doping concentration changes the bad gap, but has a minor effect on the adsorption energy. - Abstract: Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-doped boron nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

From aggregative adsorption to surface depletion

DEFF Research Database (Denmark)

Rother, Gernot; Müter, Dirk; Bock, Henry

2017-01-01

Adsorption of a short-chain nonionic amphiphile (C6E3) at the surface of mesoporous silica glass (CPG) was studied by a combination of adsorption measurements and mesoscale simulations. Adsorption measurements covering a wide composition range of the C6E3 + water system show that no adsorption...... occurs up to the critical micelle concentration, at which a sharp increase of adsorption is observed that is attributed to ad-micelle formation at the pore walls. Intriguingly, as the concentration is increased further, the surface excess of the amphiphile begins to decrease and eventually becomes...

Adsorption of ammonium dinitramide (ADN) from aqueous solutions. 1. Adsorption on powdered activated charcoal.

Science.gov (United States)

Santhosh, G; Venkatachalam, S; Ninan, K N; Sadhana, R; Alwan, S; Abarna, V; Joseph, M A

2003-03-17

Investigations on the adsorption of ammonium dinitramide (NH(4)N(NO(2))(2)) (ADN) from aqueous solutions on powdered activated charcoal (PAC) were carried out in order to find out an effective and easier method of separating ADN from aqueous solutions. The effectiveness of PAC in the selective adsorption of ADN from aqueous solutions of ADN (ADN-F) and ADN in presence of sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) ions (ADN-PS) was examined and compared using batch and column methods. The adsorption process follows both Langmuir and Freundlich adsorption isotherms and the isotherm parameters for the models were determined. The observed data favor the formation of monolayer adsorption. The adsorption capacities were found to be 63.3, 119, 105.3 and 82 mg of ADN per g of PAC for ADN-F (batch), ADN-PS (batch), ADN-F (column) and ADN-PS (column), respectively. Break-through curves for ADN-F and ADN-PS were obtained for the optimization of separation of ADN from aqueous solutions. Elution curves were generated for the desorption of ADN from PAC using hot water as eluent. Copyright 2003 Elsevier Science B.V.

Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

Directory of Open Access Journals (Sweden)

Jianying Zhang

Full Text Available The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino groups to effectively remove arsenic in its toxic As(III form (arsenite predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film and internal (intraparticle diffusion can be rate-determining for As(III adsorption. Fourier transform infrared spectroscopy (FTIR indicated that the thiol and amino groups potentially responsible for As(III adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III and thiol groups, and through the surface complexation between As(III and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III adsorption capacity holds promise for the treatment of As(III containing wastewater.

Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

Energy Technology Data Exchange (ETDEWEB)

Park, Sang-Won; Leckie, J.O. [Stanford Univ., CA (United States); Siegel, M.D. [Sandia National Labs., Albuquerque, NM (United States)

1995-09-01

Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption.

Surface complexation modeling of uranyl adsorption on corrensite from the Waste Isolation Pilot Plant Site

International Nuclear Information System (INIS)

Park, Sang-Won; Leckie, J.O.; Siegel, M.D.

1995-09-01

Corrensite is the dominant clay mineral in the Culebra Dolomite at the Waste Isolation Pilot Plant. The surface characteristics of corrensite, a mixed chlorite/smectite clay mineral, have been studied. Zeta potential measurements and titration experiments suggest that the corrensite surface contains a mixture of permanent charge sites on the basal plane and SiOH and AlOH sites with a net pH-dependent charge at the edge of the clay platelets. Triple-layer model parameters were determined by the double extrapolation technique for use in chemical speciation calculations of adsorption reactions using the computer program HYDRAQL. Batch adsorption studies showed that corrensite is an effective adsorbent for uranyl. The pH-dependent adsorption behavior indicates that adsorption occurs at the edge sites. Adsorption studies were also conducted in the presence of competing cations and complexing ligands. The cations did not affect uranyl adsorption in the range studied. This observation lends support to the hypothesis that uranyl adsorption occurs at the edge sites. Uranyl adsorption was significantly hindered by carbonate. It is proposed that the formation of carbonate uranyl complexes inhibits uranyl adsorption and that only the carbonate-free species adsorb to the corrensite surface. The presence of the organic complexing agents EDTA and oxine also inhibits uranyl sorption

Removal of Remazol brilliant violet textile dye by adsorption using rice hulls

Directory of Open Access Journals (Sweden)

Geyse Adriana Corrêa Ribeiro

Full Text Available Abstract The release of industrial effluents into the environment causes widespread contamination of aquatic systems. Adsorption is seen as one of the most promising treatment processes, and lignocellulosic materials have gained prominence as adsorbents. This study investigates the potential of rice hulls, either in natura or treated with nitric acid, as adsorbents for removal of the dye. The adsorbents were characterized by infrared spectroscopy, solid state 13C-NMR, thermogravimetric analysis, and pH at point of zero charge. The dye adsorption experiments were carried out in batch mode, using different experimental conditions. The kinetic adsorption data could be fitted using the model of Elovich. The Freundlich model provided the best fit to the isothermal data. The thermodynamic parameters confirmed the spontaneity of the adsorption process. These adsorbents offer an alternative for dye removal, with advantages including biomass availability and low cost.

Bicarbonate adsorption band of the chromatography for carbon isotope separation using anion exchangers

International Nuclear Information System (INIS)

Takeda, Kunihiko; Obanawa, Heiichiro; Hata, Masahisa; Sato, Katsuya

1985-01-01

The equilibria of bicarbonate ion between two phases were studied for the carbon isotope separation using anion exchangers. The condition of the formation of a bicarbonate adsorption band was quantitatively discussed. The formation of the adsorption band depends on the difference of S-potential which is the sum of the standard redection chemical potentials and L-potential which is the sum of the reduction chemical potential. The isotopic separation factor observed was about 1.012, independent of the concentrations of acid and alkali in the solutions. The isotopic separation factor was considered to be determined by the reaction of bicarbonate ion on anion exchangers and carbon dioxide dissolved in solutions. The enriched carbon isotope whose isotopic abundance ratio ( 13 C/ 12 C) was 1.258 was obtained with the column packed with anion exchangers. (author)

Preferable adsorption of phosphate using lanthanum-incorporated porous zeolite: Characteristics and mechanism

Science.gov (United States)

He, Yinhai; Lin, Hai; Dong, Yingbo; Wang, Liang

2017-12-01

The adsorbent, where lanthanum oxide was incorporated onto porous zeolite (La-Z), of preferable adsorption towards phosphate was prepared by hydrothermal synthesis. Based on pH effect results, La-Z would effectively sequestrate phosphate over wider pH range of 3.0-7.0, alkaline conditions were unfavorable for phosphate. The adsorption of phosphate was not significantly influenced by ionic strength and by coexisting anions of chloride, nitrate and sulfate but bicarbonate showed slightly greater negative effects, indicating La-Z possessed highly selectivity to phosphate. Adsorption of phosphate could be well fitted by pseudo-second-order model and the process was mainly controlled by intra-particle diffusion. Equilibrium adsorption demonstrated that Langmuir model was more suitable than Freundlich model for description phosphate adsorption and the adsorption capacity was 17.2 mg P g-1, which exhibited 95% utilization of incorporated La. Over 95% phosphate was eliminated in real effluent treatment when the dose was 2 g L-1. The underlying mechanism for phosphate capture was probed with Zeta potential and X-ray photoelectron spectroscope analysis, and the formation of La-P inner-sphere complexation was testified to be the dominant pathway. All the results suggested that the porous zeolite-supported lanthanum oxide can serve as a promising adsorbent for phosphate removal in realistic application.

Hybrid empirical--theoretical approach to modeling uranium adsorption

International Nuclear Information System (INIS)

Hull, Larry C.; Grossman, Christopher; Fjeld, Robert A.; Coates, John T.; Elzerman, Alan W.

2004-01-01

An estimated 330 metric tons of U are buried in the radioactive waste Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). An assessment of U transport parameters is being performed to decrease the uncertainty in risk and dose predictions derived from computer simulations of U fate and transport to the underlying Snake River Plain Aquifer. Uranium adsorption isotherms were measured for 14 sediment samples collected from sedimentary interbeds underlying the SDA. The adsorption data were fit with a Freundlich isotherm. The Freundlich n parameter is statistically identical for all 14 sediment samples and the Freundlich K f parameter is correlated to sediment surface area (r 2 =0.80). These findings suggest an efficient approach to material characterization and implementation of a spatially variable reactive transport model that requires only the measurement of sediment surface area. To expand the potential applicability of the measured isotherms, a model is derived from the empirical observations by incorporating concepts from surface complexation theory to account for the effects of solution chemistry. The resulting model is then used to predict the range of adsorption conditions to be expected in the vadose zone at the SDA based on the range in measured pore water chemistry. Adsorption in the deep vadose zone is predicted to be stronger than in near-surface sediments because the total dissolved carbonate decreases with depth

Batch study, equilibrium and kinetics of adsorption of naphthalene using waste tyre rubber granules

Directory of Open Access Journals (Sweden)

Felix A. Aisien

2014-04-01

Full Text Available The potential use of waste tyre rubber granules (WTRG for the batch adsorption of naphthalene from aqueous solutions was investigated. The effect of various operational variables such as contact time, initial naphthalene concentration, adsorbent dose, size of adsorbent particles, and temperature of solution on the adsorption capacity of WTRG was evaluated. The adsorption of naphthalene by WTRG was a fast kinetic process with an equilibrium contact time of 60 min. A low temperature (5°C, small adsorbent particle size (0.212 mm and higher adsorbent dosage favored the adsorption process. Results of isotherm studies revealed that adsorption of naphthalene was best described by the Langmuir isotherm equation (R2=0.997 while the kinetics of the process was best described by the Lagergren pseudofirst order kinetic equation (R2=0.998. This study has demonstrated the suitability of WTRG for the removal of naphthalene from aqueous solution.

Adsorption of phenolic compound by aged-refuse

Energy Technology Data Exchange (ETDEWEB)

Chai Xiaoli [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)]. E-mail: xlchai@mail.tongji.edu.cn; Zhao Youcai [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)

2006-09-01

The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic.

Adsorption of phenolic compound by aged-refuse

International Nuclear Information System (INIS)

Chai Xiaoli; Zhao Youcai

2006-01-01

The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic

Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

Science.gov (United States)

Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

2011-08-01

Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

Adsorption of antibiotics on microplastics.

Science.gov (United States)

Li, Jia; Zhang, Kaina; Zhang, Hua

2018-06-01

Microplastics and antibiotics are two classes of emerging contaminants with proposed negative impacts to aqueous ecosystems. Adsorption of antibiotics on microplastics may result in their long-range transport and may cause compound combination effects. In this study, we investigated the adsorption of 5 antibiotics [sulfadiazine (SDZ), amoxicillin (AMX), tetracycline (TC), ciprofloxacin (CIP), and trimethoprim (TMP)] on 5 types of microplastics [polyethylene (PE), polystyrene (PS), polypropylene (PP), polyamide (PA), and polyvinyl chloride (PVC)] in the freshwater and seawater systems. Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD) analysis revealed that microplastics have different surface characterizes and various degrees of crystalline. Adsorption isotherms demonstrated that PA had the strongest adsorption capacity for antibiotics with distribution coefficient (K d ) values ranged from 7.36 ± 0.257 to 756 ± 48.0 L kg -1 in the freshwater system, which can be attributed to its porous structure and hydrogen bonding. Relatively low adsorption capacity was observed on other four microplastics. The adsorption amounts of 5 antibiotics on PS, PE, PP, and PVC decreased in the order of CIP > AMX > TMP > SDZ > TC with K f correlated positively with octanol-water partition coefficients (Log K ow ). Comparing to freshwater system, adsorption capacity in seawater decreased significantly and no adsorption was observed for CIP and AMX. Our results indicated that commonly observed polyamide particles can serve as a carrier of antibiotics in the aquatic environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorptive removal of methyl orange from aqueous solution with metal-organic frameworks, porous chromium-benzenedicarboxylates

International Nuclear Information System (INIS)

Haque, Enamul; Lee, Ji Eun; Jang, In Tae; Hwang, Young Kyu; Chang, Jong-San; Jegal, Jonggeon; Jhung, Sung Hwa

2010-01-01

Two typical highly porous metal-organic framework (MOF) materials based on chromium-benzenedicarboxylates (Cr-BDC) obtained from Material of Institute Lavoisier with special structure of MIL-101 and MIL-53 have been used for the adsorptive removal of methyl orange (MO), a harmful anionic dye, from aqueous solutions. The adsorption capacity and adsorption kinetic constant of MIL-101 are greater than those of MIL-53, showing the importance of porosity and pore size for the adsorption. The performance of MIL-101 improves with modification: the adsorption capacity and kinetic constant are in the order of MIL-101 < ethylenediamine-grafted MIL-101 < protonated ethylenediamine-grafted MIL-101 (even though the porosity and pore size are slightly decreased with grafting and further protonation). The adsorption capacity of protonated ethylenediamine-grafted MIL-101 decreases with increasing the pH of an aqueous MO solution. These results suggest that the adsorption of MO on the MOF is at least partly due to the electrostatic interaction between anionic MO and a cationic adsorbent. Adsorption of MO at various temperatures shows that the adsorption is a spontaneous and endothermic process and that the entropy increases (the driving force of the adsorption) with MO adsorption. The adsorbent MIL-101s are re-usable after sonification in water. Based on this study, MOFs can be suggested as potential re-usable adsorbents to remove anionic dyes because of their high porosity, facile modification and ready re-activation.

Adsorption of methylene blue dye from aqueous solution by sugar extracted spent rice biomass.

Science.gov (United States)

Ur Rehman, Muhammad Saif; Kim, Ilgook; Han, Jong-In

2012-10-15

This study was aimed at using sugar extracted spent rice biomass (SRB) as a potential adsorbent to remove methylene blue (MB) dye from aqueous solution. The SRB was used without any modification. A three factor full factorial experimental design (2(3)) was employed to investigate the effect of factors (adsorbent dose, dye concentration, temperature) and their interaction on the adsorption capacity and color removal. Two levels for each factor were used; adsorbent dose (0.25-0.5g/100mL), dye concentration (25-50mg/L), and temperature (25-45°C). Initial dye concentration and adsorbent dosage were found as significant factors for the adsorption of MB dye. Langmuir isotherm (R(2)>0.998) best explained the equilibrium of MB adsorption on SRB with monolayer adsorption capacity of 8.13mg/g. The pseudo-second order model (R(2)>0.999) was best fitted to explain the adsorption kinetics. Thermodynamic investigation revealed that the adsorption process was spontaneous, endothermic, and was feasible to treat dyeing wastewater. Copyright © 2012 Elsevier Ltd. All rights reserved.

A modified Poisson-Boltmann model including charge regulation for the adsorption of ionizable polyelectrolytes to charged interfaces, applied to lysozyme adsorption on silica

NARCIS (Netherlands)

Biesheuvel, P.M.; Veen, van der M.; Norde, W.

2005-01-01

The equilibrium adsorption of polyelectrolytes with multiple types of ionizable groups is described using a modified Poisson-Boltzmann equation including charge regulation of both the polymer and the interface. A one-dimensional mean-field model is used in which the electrostatic potential is

Adsorption of ethanol on V2O5 (010) surface for gas-sensing applications: Ab initio investigation

International Nuclear Information System (INIS)

Qin, Yuxiang; Cui, Mengyang; Ye, Zhenhua

2016-01-01

Highlights: • Ethanol adsorbed on V 2 O 5 (010) surface was investigated by ab initio calculations. • Ethanol prefers to adsorb on “Hill”-like surface, rather than“Valley”-like region. • Surface O 1(H) site plays a key role to dominate the ethanol adsorption process. • Sensing mechanism is related with electronic structure and electron redistribution. • Gas sensitivity is reflected by quantitative electron population analysis. - Abstract: The adsorption of ethanol on V 2 O 5 (010) surface was investigated by means of density functional theory (DFT) with a combined generalized gradient approximation (GGA) plus Hubbard U approach to exploit the potential sensing applications. The adsorption configurations were first constructed by considering different orientations of ethanol molecule to V and O sites on the “Hill”- and “Valley”-like regions of corrugated (010) surface. It is found that ethanol molecule can adsorb on whole surface in multiple stable configurations. Nevertheless the molecular adsorption on the “Hill”-like surface is calculated to occur preferentially, and the single coordinated oxygen on “Hill”-like surface (O 1(H) ) acting as the most energetically favorable adsorption site shows the strongest adsorption ability to ethanol molecule. Surface adsorption of ethanol tunes the electronic structure of V 2 O 5 and cause an n-doping effect. As a consequence, the Fermi levels shift toward the conductive bond increasing the charge carrier concentration of electrons in adsorbed V 2 O 5 . The sensitive electronic structure and the multiple stable configurations to ethanol adsorption highlight the high adsorption activity and then the potential of V 2 O 5 (010) surface applied to high sensitive sensor for ethanol vapor detection. Further Mulliken population and Natural bond orbital (NBO) calculations quantify the electron transfer from the adsorbed ethanol to the surface, and correlates the adsorption ability of surface sites

Adsorption from solutions of non-electrolytes

CERN Document Server

Kipling, J J

1965-01-01

Adsorption from Solutions of Non-Electrolytes provides a general discussion of the subject, which has so far been given little or no attention in current textbooks of physical chemistry. A general view of the subject is particularly needed at a time when we wish to see how far it will be possible to use theories of solutions to explain the phenomena of adsorption. The book opens with an introductory chapter on the types of interface, aspects of adsorption from solution, types of adsorption, and classification of systems. This is followed by separate chapters on experimental methods, adsorption

Evaluation of adsorption of uranium from aqueous solution using biochar materials

Energy Technology Data Exchange (ETDEWEB)

Correa, Wagner Clayton; Guilhen, Sabine Neusatz; Ortiz, Nilce; Fungaro, Denise Alves, E-mail: wcorrea@ipen.br, E-mail: snguilhen@ipen.br, E-mail: notriz@ipen.br, E-mail: dfungaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Uranium is present in the environment as a result of leaching from natural deposits and activities associated with nuclear fuel, copper mining, uranium mining, milling industry, etc. For the purpose of protecting ecosystem stability and public health, it is crucial to eliminate uranium from aqueous solutions before they are discharged into the environment. Various technologies have been used for removing U(VI) ions from aqueous systems. Among these methods, adsorption has been applied in wastewater because of simple operation procedure and high removal efficiency. Brazil is the largest producer of charcoal in the world, with nearly half of the woody biomass harvested for energy in Brazil being transformed into charcoal. Biochar exhibits a great potential as an adsorbent because of favorable physical/chemical surface characteristics. The objective of this work was to evaluate the adsorption potential of biochar materials prepared from pyrolysis of Bamboo (CBM), Eucalyptus (CEM) and Macauba (CMA) nuts for the removal of uranium from solutions. Adsorption experiments were carried out by a batch technique. Equilibrium adsorption experiments were performed by shaking a known amount of biochar material with 100 mL of U(VI) solution in Erlenmeyer flasks in a shaker at 120 rpm and room temperature (25 deg C) for 24 h. The adsorbent was separated by centrifugation from the solution. The U(VI) concentration remaining in the supernatant solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The influences of different experimental parameters such as solution pH and bioadsorbent dose on adsorption were investigated. The highest uranium adsorption capacity were obtained at pH 3.0 and 16 g/L biomass dosage for CMA, pH 3.0 and 12 g/L biomass dosage for CBM and pH 2.0 and 10 g/L biomass dosage for CEM. The results demonstrated that the biomass derived char can be used as a low-cost adsorbent for removal of uranium from wastewater. (author)

Evaluation of adsorption of uranium from aqueous solution using biochar materials

International Nuclear Information System (INIS)

Correa, Wagner Clayton; Guilhen, Sabine Neusatz; Ortiz, Nilce; Fungaro, Denise Alves

2015-01-01

Uranium is present in the environment as a result of leaching from natural deposits and activities associated with nuclear fuel, copper mining, uranium mining, milling industry, etc. For the purpose of protecting ecosystem stability and public health, it is crucial to eliminate uranium from aqueous solutions before they are discharged into the environment. Various technologies have been used for removing U(VI) ions from aqueous systems. Among these methods, adsorption has been applied in wastewater because of simple operation procedure and high removal efficiency. Brazil is the largest producer of charcoal in the world, with nearly half of the woody biomass harvested for energy in Brazil being transformed into charcoal. Biochar exhibits a great potential as an adsorbent because of favorable physical/chemical surface characteristics. The objective of this work was to evaluate the adsorption potential of biochar materials prepared from pyrolysis of Bamboo (CBM), Eucalyptus (CEM) and Macauba (CMA) nuts for the removal of uranium from solutions. Adsorption experiments were carried out by a batch technique. Equilibrium adsorption experiments were performed by shaking a known amount of biochar material with 100 mL of U(VI) solution in Erlenmeyer flasks in a shaker at 120 rpm and room temperature (25 deg C) for 24 h. The adsorbent was separated by centrifugation from the solution. The U(VI) concentration remaining in the supernatant solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The influences of different experimental parameters such as solution pH and bioadsorbent dose on adsorption were investigated. The highest uranium adsorption capacity were obtained at pH 3.0 and 16 g/L biomass dosage for CMA, pH 3.0 and 12 g/L biomass dosage for CBM and pH 2.0 and 10 g/L biomass dosage for CEM. The results demonstrated that the biomass derived char can be used as a low-cost adsorbent for removal of uranium from wastewater. (author)

Adsorption and desorption dynamics of citric acid anions in soil

KAUST Repository

Oburger, E.

2011-07-26

The functional role of organic acid anions in soil has been intensively investigated, with special focus on (i) microbial respiration and soil carbon dynamics, (ii) nutrient solubilization or (iii) metal detoxification and reduction of plant metal uptake. Little is known about the interaction dynamics of organic acid anions with the soil matrix and the potential impact of adsorption and desorption processes on the functional significance of these effects. The aim of this study was to characterize experimentally the adsorption and desorption dynamics of organic acid anions in five agricultural soils differing in iron and aluminium oxide contents and using citrate as a model carboxylate. Results showed that both adsorption and desorption processes were fast in all soils, reaching a steady state within approximately 1 hour. However, for a given total soil citrate concentration (ct) the steady state was critically dependent on the starting conditions of the experiment, whether most of the citrate was initially present in solution (cl) or held on the solid phase (cs). Specifically, desorption-led processes resulted in significantly smaller steady-state solution concentrations than adsorption-led processes, indicating that hysteresis occurred. As it is not possible to distinguish between different adsorption and desorption pools in soil experimentally, a new dynamic hysteresis model that relies only on measured soil solution concentrations was developed. The model satisfactorily explained experimental data and was able to predict dynamic adsorption and desorption behaviour. To demonstrate its use, we applied the model to two relevant situations involving exudation and microbial degradation. The study highlighted the complex nature of citrate adsorption and desorption dynamics in soil. We conclude that existing models need to incorporate both temporal and hysteresis components to describe realistically the role and fate of organic acids in soil processes. © 2011 The

Adsorption Mechanisms of NH3 on Chlorinated Si(100)-2 x 1 Surface

International Nuclear Information System (INIS)

Lee, Hee Soon; Choi, Cheol Ho

2012-01-01

The potential energy surfaces of ammonia molecule adsorptions on the symmetrically chlorinated Si(100)- 2 x 1 surface were explored with SIMOMM:MP2/6-31G(d). It was found that the initial nucleophilic attack by ammonia nitrogen to the surface Si forms a S N 2 type transition state, which eventually leads to an HCl molecular desorption. The second ammonia molecule adsorption requires much less reaction barrier, which can be rationalized by the surface cooperative effect. In general, it was shown that the surface Si-Cl bonds can be easily subjected to the substitution reactions by ammonia molecules yielding symmetric surface Si-NH 2 bonds, which can be a good initial template for subsequent surface chemical modifications. The ammonia adsorptions are in general more facile than the corresponding water adsorption, since ammonia is better nucleophile

Insolubilization of Chestnut Shell Pigment for Cu(II Adsorption from Water

Directory of Open Access Journals (Sweden)

Zeng-Yu Yao

2016-03-01

Full Text Available Chestnut shell pigment (CSP is melanin from an agricultural waste. It has potential as an adsorbent for wastewater treatment but cannot be used in its original state because of its solubility in water. We developed a new method to convert CSP to insolubilized chestnut shell pigment (ICSP by heating, and the Cu(II adsorption performance of ICSP was evaluated. The conversion was characterized, and the thermal treatment caused dehydration and loss of carboxyl groups and aliphatic structures in CSP. The kinetic adsorption behavior obeyed the pseudo-second-order rate law, and the equilibrium adsorption data were well described with both the Langmuir and the Freundlich isotherms. ICSP can be used as a renewable, readily-available, easily-producible, environmentally-friendly, inexpensive and effective adsorbent to remove heavy-metal from aquatic environments.

ADSORPTION MALACHITE GREEN ON NATURAL ZEOLITE

OpenAIRE

Eko Ariyanto

2012-01-01

A natural zeolite was employed as adsorbent for reducing of malachite green from aqueous solution. A batch system was applied to study the adsorption of malachite green in single system on natural zeolite. The adsorption studies indicate that malachite green in single component system follows the second-order kinetics and the adsorption is diffusion process with two stages for malachite green. Malachite green adsorption isotherm follows the Langmuir model.

Effects of polyethyleneimine adsorption on rheology of bentonite ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... The influence of the cationic polymer, polyethyleneimine polymer (PEI) on the flow behaviour of bentonite suspensions (2%, w/w), was studied. XRD, zeta potential and adsorption studies were done together with rheological measurements. The addition of PEI at concentration ranges of 10-5–4.5 g/l and ...

The dynamics of H absorption in and adsorption on Cu(111)

DEFF Research Database (Denmark)

Strömquist, J.; Bengtsson, L.; Persson, M.

1998-01-01

We have studied theoretically the dynamics of H adsorption on and adsorption in Cu(111) using a classical molecular dynamics approach. A key ingredient of this study is plane-wave and pseudopotential calculations of potential energy curves for the major high symmetry sites. These calculations...... by relaxation of the Cu atoms, these barriers are so low that, even in the rigid surface lattice situation, the absorption of an incident H atom is non-activated for impacts close to the so-called fcc and hep hollow sites. The model interaction potential that we have used in the dynamics calculations...... is determined from the calculated potential energy curves and its form is taken from a semi-empirical effective medium theory for binary compounds. The main results of the dynamics calculations are: the relaxations and thermal fluctuations of the Cu atom do not affect the absorption of H in the surface...

[Adsorption of heavy metals on the surface of birnessite relationship with its Mn average oxidation state and adsorption sites].

Science.gov (United States)

Wang, Yan; Tan, Wen-Feng; Feng, Xiong-Han; Qiu, Guo-Hong; Liu, Fan

2011-10-01

Adsorption characteristics of mineral surface for heavy metal ions are largely determined by the type and amount of surface adsorption sites. However, the effects of substructure variance in manganese oxide on the adsorption sites and adsorption characteristics remain unclear. Adsorption experiments and powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were combined to examine the adsorption characteristics of Pb2+, Cu2+, Zn2+ and Cd2+ sequestration by birnessites with different Mn average oxidation state (AOS), and the Mn AOS dependent adsorption sites and adsorption characteristics. The results show that the maximum adsorption capacity of Pb2+, Cu2+, Zn2+ and Cd2+ increased with increasing birnessite Mn AOS. The adsorption capacity followed the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. The observations suggest that there exist two sites on the surface of birnessite, i. e., high-binding-energy site (HBE site) and low-binding-energy site (LBE site). With the increase of Mn AOS for birnessites, the amount of HBE sites for heavy metal ions adsorption remarkably increased. On the other hand, variation in the amount of LBE sites was insignificant. The amount of LBE sites is much more than those of HBE sites on the surface of birnessite with low Mn AOS. Nevertheless, both amounts on the surface of birnessite with high Mn AOS are very close to each other. Therefore, the heavy metal ions adsorption capacity on birnessite is largely determined by the amount of HBE sites. On birnessite surface, adsorption of Cu2+, Zn2+, and Cd2+ mostly occurred at HBE sites. In comparison with Zn2+ and Cd2+, more Cu2+ adsorbed on the LBW sites. Pb2+ adsorption maybe occupy at both LBE sites and HBE sites simultaneously.

Adsorption performance of silver-loaded activated carbon fibers

Directory of Open Access Journals (Sweden)

Yan Xue-Feng

2018-01-01

Full Text Available Silver-loaded activated carbon fiber is prepared, and its adsorption performance is studied experimentally using five methylene blue solutions with different concentrations under three different temperature conditions. The adsorption tests show that fibers adsorption increase as the increase of temperature, and there is an optimal value for solution concentration, beyond which its adsorption will de-crease. Fibers isothermal adsorption to methylene blue is different from those by the monolayer adsorption by Langmuir model and the multilayer adsorption by Freundlich model. Through the analysis of thermodynamic parameters, Gibbs free energy, standard entropy, and standard enthalpy, it is found that the fibers adsorption to methylene blue is an exothermic process of physical adsorption.

Computational study of ethanol adsorption and reaction over rutile TiO2 (110) surfaces

KAUST Repository

Muir, J. N.

2012-01-01

Studies of the modes of adsorption and the associated changes in electronic structures of renewable organic compounds are needed in order to understand the fundamentals behind surface reactions of catalysts for future energies. Using planewave density functional theory (DFT) calculations, the adsorption of ethanol on perfect and O-defected TiO 2 rutile (110) surfaces was examined. On both surfaces the dissociative adsorption mode on five-fold coordinated Ti cations (Ti 4+ 5c) was found to be more favourable than the molecular adsorption mode. On the stoichiometric surface E ads was found to be equal to 0.85 eV for the ethoxide mode and equal to 0.76 eV for the molecular mode. These energies slightly increased when adsorption occurred on the Ti 4+ 5c closest to the O-defected site. However, both considerably increased when adsorption occurred at the removed bridging surface O; interacting with Ti 3+ cations. In this case the dissociative adsorption becomes strongly favoured (E ads = 1.28 eV for molecular adsorption and 2.27 eV for dissociative adsorption). Geometry and electronic structures of adsorbed ethanol were analysed in detail on the stoichiometric surface. Ethanol does not undergo major changes in its structure upon adsorption with its C-O bond rotating nearly freely on the surface. Bonding to surface Ti atoms is a σ type transfer from the O2p of the ethanol-ethoxide species. Both ethanol and ethoxide present potential hole traps on O lone pairs. Charge density and work function analyses also suggest charge transfer from the adsorbate to the surface, in which the dissociative adsorptions show a larger charge transfer than the molecular adsorption mode. This journal is © 2012 the Owner Societies.

Adsorptive property of rice husk for uranium

International Nuclear Information System (INIS)

Feng Yuan; Yi Facheng

2011-01-01

The adsorption experiments were researched by using the rice husk powder as the adsorbent to remove the U(VI) from aqueous solution. The affecting factors on the U(VI) removal rate such as rice husk particle size, pH, initial concentration, adsorption time, temperature and dosage of adsorbent were evaluated, kinetics and adsorption isotherm law were analyzed, and mechanisms for U(VI) removal were discussed by SEM, FT-IR and energy spectrum analysis. The results show that U(VI) removal rate increases with the decrease of the size of adsorbent, and with the increase of adsorbent dosage and temperature. The process of adsorption can be described by an equation of pseudo 2nd-order mode, and the relation coefficient is 1. The process of adsorption also fits to Freundlich isotherm (R 2 =0.995 4). The adsorption of uranium on rice husk changes the surface form of rice husk. Hydroxyl, carboxylic, P-O and Si-O are the main functional groups in the reaction with U(VI). The adsorption mechanism is mixture adsorption, including the physical and chemical adsorption. (authors)

Adsorption of ion pairs onto graphene flakes and impacts of counterions during the adsorption processes

Science.gov (United States)

Zhu, Chang; Yun, Jiena; Wang, Qian; Yang, Gang

2018-03-01

Although cations and anions are two integral constituents for all electrolytes, adsorption of ion pairs onto carbonaceous materials gains obviously less attention than adsorption of only cations or anions. Here DFT calculations are employed finding that four adsorption configurations emerge for KI onto graphene flakes (GF) instead of three for the other ion pairs. Reservation of ionic bonds is critical to their stabilities, and the bilateral configurations, where GFs couple with both cations and anions, are disfavored due to rupture of ionic bonds. Relative stabilities of two vertical configurations can be regulated and even reversed through edge-functionalization. Surprisingly, the horizontal adsorption configurations, which are global energy minima as long as present, are non-existent for a majority of ion pairs, and their existence or not is determined by the adsorption differences between halide ions and alkali ions (△Ead). Counterions effects for both cations and anions increase with the atomic electronegativities and cations correspond to stronger counterion effects; e.g., Li+ added on the other side of GFs promotes the adsorption of F- more pronouncedly than edge-functionalization. Mechanisms of electron transfers are also discussed, and three alteration patterns by counterions are observed for each type of adsorption configurations. Furthermore, addition of counterions causes band gaps to vary within a wider range that may be useful to design electronic devices.

FY-2015 Methyl Iodide Deep-Bed Adsorption Test Report

Energy Technology Data Exchange (ETDEWEB)

Soelberg, Nicholas Ray [Idaho National Lab. (INL), Idaho Falls, ID (United States); Watson, Tony Leroy [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-09-30

Nuclear fission produces fission and activation products, including iodine-129, which could evolve into used fuel reprocessing facility off-gas systems, and could require off-gas control to limit air emissions to levels within acceptable emission limits. Deep-bed methyl iodide adsorption testing has continued in Fiscal Year 2015 according to a multi-laboratory methyl iodide adsorption test plan. Updates to the deep-bed test system have also been performed to enable the inclusion of evaporated HNO₃ and increased NO₂ concentrations in future tests. This report summarizes the result of those activities. Test results showed that iodine adsorption from gaseous methyl iodide using reduced silver zeolite (AgZ) resulted in initial iodine decontamination factors (DFs, ratios of uncontrolled and controlled total iodine levels) under 1,000 for the conditions of the long-duration test performed this year (45 ppm CH3I, 1,000 ppm each NO and NO₂, very low H₂O levels [3 ppm] in balance air). The mass transfer zone depth exceeded the cumulative 5-inch depth of 4 bed segments, which is deeper than the 2-4 inch depth estimated for the mass transfer zone for adsorbing I₂ using AgZ in prior deep-bed tests. The maximum iodine adsorption capacity for the AgZ under the conditions of this test was 6.2% (6.2 g adsorbed I per 100 g sorbent). The maximum Ag utilization was 51%. Additional deep-bed testing and analyses are recommended to (a) expand the data base for methyl iodide adsorption and (b) provide more data for evaluating organic iodide reactions and reaction byproducts for different potential adsorption conditions.

Adsorption of methyl orange from aqueous solution using chitosan/diatomite composite.

Science.gov (United States)

Zhao, Peng; Zhang, Runhu; Wang, Jianglin

2017-04-01

A novel chitosan/diatomite composite was prepared by a simple mixture in the mass ratio to remove methyl orange (MO) from aqueous media in this study. The composite adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analysis. The parameters to influence the adsorption of MO were studied under such conditions as kinetics, adsorption isotherm, pH effect, and thermodynamics. The results revealed that adsorption of MO was initially rapid and the equilibrium time was reached after 40 min. The optimal value of the pH was 5.0 for better adsorption. The equilibrium data were well fitted to the Langmuir isotherm compared to the Freundlich isotherm, and exhibited the highest capacity and a removal rate of 88.37% under an initial dye concentration of 50 mg/L. The kinetic data were well described by the pseudo-second order model. The thermodynamic calculations revealed that the sorption was viable, spontaneous, and exothermic under the conditions studied. In addition, the chitosan/diatomite composite had good adsorption and desorption performance with respect to reusability after six cycles. These results showed that the chitosan/diatomite could be considered as a potential adsorbent for the removal of MO in aqueous solution.

Adsorption-desorption and leaching of pyraclostrobin in Indian soils.

Science.gov (United States)

Reddy, S Navakishore; Gupta, Suman; Gajbhiye, Vijay T

2013-01-01

Pyraclostrobin is a new broad-spectrum foliar applied and seed protectant fungicide of the strobilurin group. In this paper, adsorption-desorption of pyraclostrobin has been investigated in three different soils viz. Inceptisol (sandy loam, Delhi), Vertisol (sandy clay, Hyderabad) and Ultisol (sandy clay loam, Thrissur). Effect of organic matter and clay content on sorption was also studied in Inceptisol of Delhi. Leaching potential of pyraclostrobin as influenced by rainfall was studied in intact soil columns to confirm the results of adsorption-desorption studies. The adsorption studies were carried out at initial concentrations of 0.05, 0.1, 0.5, 1 and 1.5 μg mL(-1). The distribution coefficient (Kd) values in three test soils ranged from 4.91 to 18.26 indicating moderate to high adsorption. Among the three test soils, adsorption was the highest in Ultisol (Kd 18.26), followed by Vertisol (Kd 9.87) and Inceptisol (Kd 4.91). KF value was also highest for Ultisol soil (66.21), followed by Vertisol (40.88) and Inceptisol (8.59). S-type adsorption isotherms were observed in all the three test soils. Kd values in organic carbon-removed soil and clay-removed soil were 3.57 and 2.83 respectively, indicating lower adsorption than normal Inceptisol. Desorption studies were carried out at initial concentrations of 0.5, 1 and 1.5 μg mL(-1). Desorption was the greatest in Inceptisol, followed by Vertisol and Ultisol. Amounts of pyraclostrobin desorbed in three desorption cycles for different concentrations were 23.1-25.3%, 9.4-20.7% and 8.1-13.6% in Inceptisol, Vertisol and Ultisol respectively. Desorption was higher in clay fraction-removed and organic carbonremoved soils than normal Inceptisol. Desorption was slower than adsorption in all the test soils, indicating hysteresis effect (with hysteresis coefficient values varying from 0.05 to 0.20). Low values of hysteresis coefficient suggest high hysteresis effect indicating easy and strong adsorption, and slow

A first-principles study of gas molecule adsorption on borophene

Directory of Open Access Journals (Sweden)

Tingting Liu

2017-12-01

Full Text Available Borophene, a new two-dimensional material, was recently synthesized. The unique anisotropic structure and excellent properties of borophene have attracted considerable research interest. This paper presents a first-principles study of the adsorption of gas molecules (CO, CO2, NH3, NO, NO2 and CH4 on borophene. The adsorption configurations, adsorption energies and electronic properties of the gas molecules absorpted on borophene are determined, and the mechanisms of the interactions between the gas molecules and borophene are evaluated. We find that CO, CO2, NH3, NO and NO2 are chemisorbed on borophene, while CH4 is physisorbed on borophene. Furthermore, our calculation also indicate that CO and CO2 are chemisorbed on borophene with moderate adsorption energy and NO, NO2 and NH3 are chemisorbed on borophene via strong covalent bonds. Moreover, CO is found as an electron donor, while CO2 an electron acceptor. The chemisorption of CO and CO2 on borophene increases the electrical conductivity, so It seems that borophene has the potential to be used in high-sensitivity CO and CO2 gas sensors.

High-throughput screening of small-molecule adsorption in MOF-74

Science.gov (United States)

Thonhauser, T.; Canepa, P.

2014-03-01

Using high-throughput screening coupled with state-of-the-art van der Waals density functional theory, we investigate the adsorption properties of four important molecules, H2, CO2, CH4, and H2O in MOF-74-  with  = Be, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Nb, Ru, Rh, Pd, La, W, Os, Ir, and Pt. We show that high-throughput techniques can aid in speeding up the development and refinement of effective materials for hydrogen storage, carbon capture, and gas separation. The exploration of the configurational adsorption space allows us to extract crucial information concerning, for example, the competition of water with CO2 for the adsorption binding sites. We find that only a few noble metals--Rh, Pd, Os, Ir, and Pt--favor the adsorption of CO2 and hence are potential candidates for effective carbon-capture materials. Our findings further reveal significant differences in the binding characteristics of H2, CO2, CH4, and H2O within the MOF structure, indicating that molecular blends can be successfully separated by these nano-porous materials. Supported by DOE DE-FG02-08ER46491.

Surface study of platinum decorated graphene towards adsorption of NH{sub 3} and CH{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Rad, Ali Shokuhi, E-mail: a.shokuhi@gmail.com [Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of); Pazoki, Hossein; Mohseni, Soheil [Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of); Zareyee, Daryoush [Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of); Peyravi, Majid [Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

2016-10-01

To distinguish the potential of graphene sensors, there is a need to recognize the interaction between graphene sheet and adsorbing molecules. We used density functional theory (DFT) calculations to study the properties of pristine as well as Pt-decorated graphene sheet upon adsorption of NH{sub 3} and CH{sub 4} on its surface to exploit its potential to be as gas sensors for them. We found much higher adsorption, higher charge transfer, lower intermolecular distance, and higher orbital hybridizing upon adsorption of NH{sub 3} and CH{sub 4} gas molecules on Pt-decorated graphene compared to pristine graphene. Also our calculations reveal that the adsorption energies on Pt-decorated graphene sheet are in order of NH{sub 3} >CH{sub 4} which could be corresponded to the order of their sensitivity on this modified surface. We used orbital analysis including density of states as well as frontier molecular orbital study for all analyte-surface systems to more understanding the kind of interaction (physisorption or chemisorption). Consequently, the Pt-decorated graphene can transform the existence of NH{sub 3} and CH{sub 4} molecules into electrical signal and it may be potentially used as an ideal sensor for detection of NH{sub 3} and CH{sub 4} in ambient situation. - Highlights: • Pt-decorated graphene was investigated as an adsorbent for NH{sub 3} and CH{sub 4}. • Much higher adsorption of NH{sub 3} and CH{sub 4} on Pt-decorated graphene than pristine graphene. • Higher adsorption of NH{sub 3} compared to CH{sub 4} on Pt-decorated graphene. • Pt influences the electronic structure of graphene.

Mechanisms of chain adsorption on porous substrates and critical conditions of polymer chromatography.

Science.gov (United States)

Cimino, Richard T; Rasmussen, Christopher J; Brun, Yefim; Neimark, Alexander V

2016-11-01

Polymer adsorption is a ubiquitous phenomenon with numerous technological and healthcare applications. The mechanisms of polymer adsorption on surfaces and in pores are complex owing to a competition between various entropic and enthalpic factors. Due to adsorption of monomers to the surface, the chain gains in enthalpy yet loses in entropy because of confining effects. This competition leads to the existence of critical conditions of adsorption when enthalpy gain and entropy loss are in balance. The critical conditions are controlled by the confining geometry and effective adsorption energy, which depends on the solvent composition and temperature. This phenomenon has important implications in polymer chromatography, since the retention at the critical point of adsorption (CPA) is chain length independent. However, the mechanisms of polymer adsorption in pores are poorly understood and there is an ongoing discussion in the theoretical literature about the very existence of CPA for polymer adsorption on porous substrates. In this work, we examine the mechanisms of chain adsorption on a model porous substrate using Monte Carlo (MC) simulations. We distinguish three adsorption mechanisms depending on the chain location: on external surface, completely confined in pores, and also partially confined in pores in so-called "flower" conformations. The free energies of different conformations of adsorbed chains are calculated by the incremental gauge cell MC method that allows one to determine the partition coefficient as a function of the adsorption potential, pore size, and chain length. We confirm the existence of the CPA for chain length independent separation on porous substrates, which is explained by the dominant contributions of the chain adsorption at the external surface, in particular in flower conformations. Moreover, we show that the critical conditions for porous and nonporous substrates are identical and depend only on the surface chemistry. The theoretical

ADSORPTION MALACHITE GREEN ON NATURAL ZEOLITE

Directory of Open Access Journals (Sweden)

Eko Ariyanto

2012-02-01

Full Text Available A natural zeolite was employed as adsorbent for reducing of malachite green from aqueous solution. A batch system was applied to study the adsorption of malachite green in single system on natural zeolite. The adsorption studies indicate that malachite green in single component system follows the second-order kinetics and the adsorption is diffusion process with two stages for malachite green. Malachite green adsorption isotherm follows the Langmuir model.

Heavy metals adsorption by novel EDTA-modified chitosan-silica hybrid materials.

Science.gov (United States)

Repo, Eveliina; Warchoł, Jolanta K; Bhatnagar, Amit; Sillanpää, Mika

2011-06-01

Novel adsorbents were synthesized by functionalizing chitosan-silica hybrid materials with (ethylenediaminetetraacetic acid) EDTA ligands. The synthesized adsorbents were found to combine the advantages of both silica gel (high surface area, porosity, rigid structure) and chitosan (surface functionality). The Adsorption potential of hybrid materials was investigated using Co(II), Ni(II), Cd(II), and Pb(II) as target metals by varying experimental conditions such as pH, contact time, and initial metal concentration. The kinetic results revealed that the pore diffusion process played a key role in adsorption kinetics, which might be attributed to the porous structure of synthesized adsorbents. The obtained maximum adsorption capacities of the hybrid materials for the metal ions ranged from 0.25 to 0.63 mmol/g under the studied experimental conditions. The adsorbent with the highest chitosan content showed the best adsorption efficiency. Bi-Langmuir and Sips isotherm model fitting to experimental data suggested the surface heterogeneity of the prepared adsorbents. In multimetal solutions, the hybrid adsorbents showed the highest affinity toward Pb(II). Copyright © 2011 Elsevier Inc. All rights reserved.

Exact matrix treatment of statistical mechanical lattice model of adsorption induced gate opening in metal-organic frameworks

International Nuclear Information System (INIS)

Dunne, Lawrence J; Manos, George

2015-01-01

Here we present a statistical mechanical lattice model which is exactly solvable using a matrix method and allows treatment of adsorption induced gate opening structural transformations of metal-organic frameworks which are nanoporous materials with exceptional adsorption properties. Modelling of these structural changes presents a serious theoretical challenge when the solid and gas species are treated in an even handed way. This exactly solvable model complements other simulation based approaches. The methodology presented here highlights the competition between the potential for adsorption and the energy required for structural transition as a driving force for the features in the adsorption isotherms. (paper)

Effective NH2-grafting on attapulgite surfaces for adsorption of reactive dyes

International Nuclear Information System (INIS)

Xue, Ailian; Zhou, Shouyong; Zhao, Yijiang; Lu, Xiaoping; Han, Pingfang

2011-01-01

Highlights: → We prepared a new amine functionalized adsorbent derived from clay-based material. → Attapulgite surface was modified with 3-aminopropyltriethoxysilane. → Some modification parameters affecting the adsorption potential were investigated. → Enhance the attapulgite adsorptive capacity for reactive dyes from aqueous solutions. - Abstract: The amine moiety has an important function in many applications, including, adsorption, catalysis, electrochemistry, chromatography, and nanocomposite materials. We developed an effective adsorbent for aqueous reactive dye removal by modifying attapulgite with an amino-terminated organosilicon (3-aminopropyltriethoxysilane, APTES). Surface properties of the APTES-modified attapulgite were characterized by the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption. We evaluated the impact of solvent, APTES concentration, water volume, reaction time, and temperature on the surface modification. NH 2 -attapulgite was used to remove reactive dyes in aqueous solution and showed very high adsorption rates of 99.32%, 99.67%, and 96.42% for Reactive Red 3BS, Reactive Blue KE-R and Reactive Black GR, respectively. These powerful dye removal effects were attributed to strong electrostatic interactions between reactive dyes and the grafted NH 2 groups.

Thiol-functionalized polysilsesquioxane as efficient adsorbent for adsorption of Hg(II) and Mn(II) from aqueous solution

International Nuclear Information System (INIS)

Niu, Yuzhong; Qu, Rongjun; Liu, Xiguang; Mu, Lei; Bu, Baihui; Sun, Yuting; Chen, Hou; Meng, Yangfeng; Meng, Lina; Cheng, Lin

2014-01-01

Highlights: • PMPSQ was promising adsorbent for the removal of Hg(II) and Mn(II). • The adsorption kinetics followed the pseudo-second-order model. • The adsorption isotherms can be described by the monolayer Langmuir model. • The adsorption was controlled by film diffusion and chemical ion-exchange mechanism. - Abstract: Thiol-functionalized polysilsesquioxane was synthesized and used for the adsorption of Hg(II) and Mn(II) from aqueous solution. Results showed that the optimal pH was about 6 and 5 for Hg(II) and Mn(II), respectively. Adsorption kinetics showed that the adsorption equilibriums were established within 100 min and followed pseudo-second-order model. Adsorption isotherms revealed that the adsorption capacities increased with the increasing of temperature. The adsorption was found to be well described by the monolayer Langmuir isotherm model and took place by chemical ion-exchange mechanism. The thermodynamic properties indicated the adsorption processes were spontaneous and endothermic nature. Selectively adsorption showed that PMPSQ can selectively adsorb Hg(II) from binary ion systems in the presence of the coexistent ions Mn(II), Cu(II), Pb(II), Co(II), and Ni(II). Based on the results, it is concluded that PMPSQ had comparable high adsorption efficiency and could be potentially used for the removal of Hg(II) and Mn(II) from aqueous solution

Adsorption of Volatile Organic Compounds from Aqueous Solution by Granular Activated Carbon in Batch System

International Nuclear Information System (INIS)

Zeinali, F.; Ghoreyshi, A. A.; Najafpour, G.

2011-01-01

Chlorinated hydrocarbons and aromatics are the major volatile organic compounds that contaminate the ground water and industrial waste waters. The best way to overcome this problem is to recover the dissolved compounds in water. In order to evaluate the potential ability of granular activated carbon for recovery of volatile organic compounds from water, the equilibrium adsorption was investigated. This study deals with the adsorption of dichloromethane as a typical chlorinated volatile organic compound and toluene as the representative of aromatic volatile organic compounds on a commercial granular activated carbon. The adsorption isotherms of these two volatile organic compounds on granular activated carbon were measured at three different temperatures, toluene at 293, 303 and 313 K and dichloromethane at 298, 303 and 313 K within their solubility concentration range in water. The maximum adsorption capacity of dichloromethane and toluene adsorption by granular activated carbon was 4 and 0.2 mol/Kg-1, respectively. The experimental data obtained were correlated with different adsorption isotherm models. The Langmuir model was well adapted to the description of dichloromethane adsorption on granular activated carbon at all three temperatures, while the adsorption of toluene on granular activated carbon was found to be well described by the Langmuir-BET hybrid model at all three temperatures. The heat of adsorption was also calculated based on the thermodynamic equation of Clausius Clapeyron, which indicates the adsorption process is endothermic for both compounds.

Cadmium adsorption by coal combustion ashes-based sorbents-Relationship between sorbent properties and adsorption capacity

Energy Technology Data Exchange (ETDEWEB)

Balsamo, Marco; Di Natale, Francesco; Erto, Alessandro; Lancia, Amedeo [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, Piazzale Vincenzo Tecchio 80, 80125 Napoli (Italy); Montagnaro, Fabio, E-mail: fabio.montagnaro@unina.it [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy); Santoro, Luciano [Dipartimento di Chimica, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant' Angelo, 80126 Napoli (Italy)

2011-03-15

A very interesting possibility of coal combustion ashes reutilization is their use as adsorbent materials, that can also take advantage from proper beneficiation techniques. In this work, adsorption of cadmium from aqueous solutions was taken into consideration, with the emphasis on the intertwining among waste properties, beneficiation treatments, properties of the beneficiated materials and adsorption capacity. The characterization of three solid materials used as cadmium sorbents (as-received ash, ash sieved through a 25 {mu}m-size sieve and demineralized ash) was carried out by chemical analysis, infrared spectroscopy, laser granulometry and mercury porosimetry. Cadmium adsorption thermodynamic and kinetic tests were conducted at room temperature, and test solutions were analyzed by atomic absorption spectrophotometry. Maximum specific adsorption capacities resulted in the range 0.5-4.3 mg g{sup -1}. Different existing models were critically considered to find out an interpretation of the controlling mechanism for adsorption kinetics. In particular, it was observed that for lower surface coverage the adsorption rate is governed by a linear driving force while, once surface coverage becomes significant, mechanisms such as the intraparticle micropore diffusion may come into play. Moreover, it was shown that both external fluid-to-particle mass transfer and macropore diffusion hardly affect the adsorption process, which was instead regulated by intraparticle micropore diffusion: characteristic times for this process ranged from 4.1 to 6.1 d, and were fully consistent with the experimentally observed equilibrium times. Results were discussed in terms of the relationship among properties of beneficiated materials and cadmium adsorption capacity. Results shed light on interesting correlations among solid properties, cadmium capture rate and maximum cadmium uptake.

Adsorption--from theory to practice.

Science.gov (United States)

Dabrowski, A

2001-10-08

Adsorption at various interfaces has concerned scientists since the beginning of this century. This phenomenon underlies a number of extremely important processes of utilitarian significance. The technological, environmental and biological importance of adsorption can never be in doubt. Its practical applications in industry and environmental protection are of paramount importance. The adsorption of substrates is the first stage in many catalytic processes. The methods for separation of mixtures on a laboratory and on an industrial scale are increasingly based on utilising the change in concentration of components at the interface. Moreover, such vital problems as purification of water, sewages, air and soil are involved here too. On the other hand, many areas in which technological innovation has covered adsorption phenomena have been expanded more through art and craft than through science. A basic understanding of the scientific principles is far behind; in part because the study of interfaces requires extremely careful experimentation if meaningful and reproducible results are to be obtained. In recent years, however, considerable effort has been increasingly directed toward closing the gap between theory and practice. Crucial progress in theoretical description of the adsorption has been achieved, mainly through the development of new theoretical approaches formulated on a molecular level, by means of computer simulation methods and owing to new techniques which examine surface layers or interfacial regions. Moreover, during the last 15 years new classes of solid adsorbents have been developed, such as activated carbon fibres and carbon molecular sieves, fullerenes and heterofullerenes, microporous glasses and nanoporous--both carbonaceous and inorganic--materials. Nanostructured solids are very popular in science and technology and have gained extreme interest due to their sorption, catalytic, magnetic, optical and thermal properties. Although the development

Characterization of trichloroethylene adsorption onto waste biocover soil in the presence of landfill gas.

Science.gov (United States)

He, Ruo; Su, Yao; Kong, Jiaoyan

2015-09-15

Waste biocover soils (WBS) have been demonstrated to have great potential in mitigating trichloroethylene (TCE) emission from landfills, due to the relatively high TCE-degrading capacity. In this study, the characteristics of TCE adsorption on WBS in the presence of the major landfill gas components (i.e., CH4 and CO2) were investigated in soil microcosms. The adsorption isotherm of TCE onto WBS was fitted well with linear model within the TCE concentrations of 7000 ppmv. The adsorption capacity of TCE onto WBS was affected by temperature, soil moisture content and particle size, of which, temperature was the dominant factor. The adsorption capacity of TCE onto the experimental materials increased with the increasing organic matter content. A significantly positive correlation was observed between the adsorption capacity of TCE and the organic matter content of experimental materials that had relatively higher organic content (r = 0.988, P = 0.044). To better understand WBS application in practice, response surface methodology was developed to predict TCE adsorption capacity and emissions through WBS in different landfills in China. These results indicated that WBS had high adsorption capacity of TCE in LFG and temperature should be paid more attention to manipulate WBS to reduce TCE emissions from landfills. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption of Pb(II) from fish sauce using carboxylated cellulose nanocrystal: Isotherm, kinetics, and thermodynamic studies.

Science.gov (United States)

Wang, Nan; Jin, Ru-Na; Omer, A M; Ouyang, Xiao-Kun

2017-09-01

In the present study, a new adsorbent based on carboxylated cellulose nanocrystal (CCN) was developed for the adsorption of Pb(II) from fish sauce. The prepared adsorbent material was characterized by zeta potential, FT-IR, XRD, and XPS tools. The changes in the morphological structure of the developed CCN surface were evidenced by SEM and TEM. The favorable adsorption conditions were selected by studying the contact time, initial concentration, temperature, and concentration of the used glutamic acid and NaCl. The results indicated that the Langmuir isotherm model agrees very well with experimental adsorption data (R 2 =0.9962) with a maximum adsorption capacity 232.56mg/g of Pb(II) at 293.2K. Additionally, data of the adsorption kinetics follow the pseudo-second-order kinetics (R 2 >0.9990). On the other hand, the thermodynamics studies show that the adsorption process is spontaneous and endothermic. Furthermore, the developed CCN could be regenerated using acid treatment with a good reusability for Pb(II) adsorption. The results clearly indicated that the synthesized CCN could be effectively applied as a new material for Pb(II) adsorption from fish sauce solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of the potassium adsorption capacity of a potassium adsorption filter during rapid blood transfusion.

Science.gov (United States)

Matsuura, H; Akatsuka, Y; Muramatsu, C; Isogai, S; Sugiura, Y; Arakawa, S; Murayama, M; Kurahashi, M; Takasuga, H; Oshige, T; Yuba, T; Mizuta, S; Emi, N

2015-05-01

The concentration of extracellular potassium in red blood cell concentrates (RCCs) increases during storage, leading to risk of hyperkalemia. A potassium adsorption filter (PAF) can eliminate the potassium at normal blood transfusion. This study aimed to investigate the potassium adsorption capacity of a PAF during rapid blood transfusion. We tested several different potassium concentrations under a rapid transfusion condition using a pressure bag. The adsorption rates of the 70-mEq/l model were 76·8%. The PAF showed good potassium adsorption capacity, suggesting that this filter may provide a convenient method to prevent hyperkalemia during rapid blood transfusion. © 2015 International Society of Blood Transfusion.

Adsorption and activation of methane and methanol on Pt(100) surface: a density functional study

International Nuclear Information System (INIS)

Moussounda, P.S.

2006-11-01

The activation of methane (CH 4 ) and methanol (CH 3 OH) on Pt(100) surface has been investigated using density functional theory calculations based on plane-wave basis and pseudo-potential. We optimised CH 4 /Pt(100) system. The calculated adsorption energies over the top, bridge and hollow sites are small, weakly dependent on the molecular orientation. The nature of the CH 4 -Pt interaction was examined through the electronic structure changes. The adsorption of methyl (CH 3 ) and hydrogen (H) and the co-adsorption of CH 3 +H were also calculated. From these results, we examined the dissociation of CH 4 to CH 3 +H, and the activation energies found are in good agreement with the experimental and theoretical values. The activation of CH 3 OH/Pt(100) has been studied. All the sites have almost the same adsorption energy. The adsorption of oxygen (O) and the co-adsorption of CH 4 and O were also examined. In addition, the formation of CH 3 OH assuming a one-step mechanism step via the co-adsorption of CH 4 +O has been studied and the barrier height was found to be high. (authors)

Dibenzothiophene adsorption at boron doped carbon nanoribbons studied within density functional theory

Energy Technology Data Exchange (ETDEWEB)

López-Albarrán, P. [Facultad de Ingeniería en Tecnología de la Madera, Universidad Michoacana de San Nicolás de Hidalgo, Santiago Tapia 403, CP 58000, Morelia, Michoacán (Mexico); Navarro-Santos, P., E-mail: pnavarrosa@conacyt.mx [Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Santiago Tapia 403, CP 58000, Morelia, Michoacán (Mexico); Garcia-Ramirez, M. A. [Research Centre for Innovation in Aeronautical Engineering, Universidad Autónoma de Nuevo León, Ciudad Universitaria, San Nicolás de los Garza, CP 66451 Nuevo León (Mexico); Ricardo-Chávez, J. L. [Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Lomas 4" asección, CP 78216, San Luis Potosí, S. L. P. (Mexico)

2015-06-21

The adsorption of dibenzothiophene (DBT) on bare and boron-doped armchair carbon nanoribbons (ACNRs) is being investigated in the framework of the density functional theory by implementing periodic boundary conditions that include corrections from dispersion interactions. The reactivity of the ACNRs is characterized by using the Fukui functions as well as the electrostatic potential as local descriptors. Non-covalent adsorption mechanism is found when using the local Perdew-Becke-Ernzerhof functional, regardless of the DBT orientation and adsorption location. The dispersion interactions addition is a milestone to describe the adsorption process. The charge defects introduced in small number (i.e., by doping with B atoms), within the ACNRs increases the selectivity towards sulfur mainly due to the charge depletion at B sites. The DBT magnitude in the adsorption energy shows non-covalent interactions. As a consequence, the configurations where the DBT is adsorbed on a BC{sub 3} island increase the adsorption energy compared to random B arrangements. The stability of these configurations can be explained satisfactorily in terms of dipole interactions. Nevertheless, from the charge-density difference analysis and the weak Bader charge-distribution interactions cannot be ruled out completely. This is why the electronic properties of the ribbons are analyzed in order to elucidate the key role played by the B and DBT states in the adsorbed configurations.

First principles study of dissolved oxygen water adsorption on Fe (001 surfaces

Directory of Open Access Journals (Sweden)

Dong ZHANG

2018-02-01

Full Text Available In order to study the mechanism of dissolved oxygen content on the surface corrosion behavior of Fe-based heat transfer, the first principle is used to study the adsorption of O2 monomolecular, H2O monolayer and dissolved oxygen system on Fe-based heat transfer surface. The GGA/PBE approximation is used to calculate the adsorption energy, state density and population change during the adsorption process. Calculations prove that when the dissolved oxygen is adsorbed on the Fe-based surface, the water molecule tends to adsorb at the top sites, and the oxygen molecule tends to adsorb at Griffiths. When the H2O molecule adsorbs and interacts on the Fe (001 surface, the charge distribution of the interfacial double electric layer changes to cause the Fe atoms to lose electrons, resulting in the change of the surface potential. When the O2 molecule adsorbs on the Fe (001 crystal surfaces, the electrons on the Fe (001 surface are lost and the surface potential increases. O2 molecule and the surface of the Fe atoms are prone to electron transfer, in which O atom's 2p orbit for the adsorption of O2 molecule on Fe (001 crystal surface play a major role. With the increase of the proportion of O2 molecule in the dissolved oxygen water, the absolute value of the adsorption energy increases, and the interaction of the Fe-based heat transfer surface is stronger. This study explores the influence law of different dissolved oxygen on the Fe base heat exchange surface corrosion, and the base metal corrosion mechanism for experimental study provides a theoretical reference.

[Treatment of organic waste gas by adsorption rotor].

Science.gov (United States)

Zhu, Run-Ye; Zheng, Liang-Wei; Mao, Yu-Bo; Wang, Jia-De

2013-12-01

The adsorption rotor is applicable to treating organic waste gases with low concentration and high air volume. The performance of adsorption rotor for purifying organic waste gases was investigated in this paper. Toluene was selected as the simulative gaseous pollutant and the adsorption rotor was packed with honeycomb modified 13X molecular sieves (M-13X). Experimental results of the fixed adsorption and the rotor adsorption were analyzed and compared. The results indicated that some information on the fixed adsorption was useful for the rotor adsorption. Integrating the characteristics of the adsorbents, waste gases and the structures of the rotor adsorption, the formulas on optimal rotor speed and cycle removal efficiency of the adsorption rotor were deduced, based on the mass and heat balances of the adsorbing process. The numerical results were in good agreement with the experimental data, which meant that the formulas on optimal rotor speed and cycle removal efficiency could be effectively applied in design and operation of the adsorption rotor.

Potassium adsorption behaviour of three Malaysian rice soils

International Nuclear Information System (INIS)

Choudhury, A.T.M.A.; Khanif, Y.M.

2003-01-01

Potassium (K) deficiency exists in different rice growing areas of Malaysia. A study on K adsorption was carried out in three Malaysian rice soils (Guar, Hutan and Kangar series) using six levels of K (0.00,28.77, 33.57, 38.37, 43.16 and 47.96 mmol kg/sup -1/). The data on K adsorption were fitted into Langmuir, Freundlich, and Temkin adsorption equations. Adsorption data were also correlated with pH, cation exchange capacity and organic matter content of the soils. Potassium adsorption increased linearly with increasing level of added K in all the three soils. The rate of increase was the highest in Guar series followed by Kangar and Hutan series, respectively. Potassium adsorption in two soils (Hutan and Kangar) fitted into Langmuir equation while he adsorption data in Guar series did not fit into this equation. Adsorption data in none of the soils fitted well in Freundlich and Temkin adsorption equations. Correlation between K adsorption and pH was significant (r = 0.881,), whereas, correlation of K adsorption with either organic matter content or cation exchange capacity was non-significant. The results of this study indicated that K adsorption is mainly dependent on soil pH. In soils with higher adsorption capacity, more K fertilizer may be needed to get immediate crop response. (author)

Adsorptive removal of congo red dye from aqueous solution using bael shell carbon

International Nuclear Information System (INIS)

Ahmad, Rais; Kumar, Rajeev

2010-01-01

This study investigates the potential use of bael shell carbon (BSC) as an adsorbent for the removal of congo red (CR) dye from aqueous solution. The effect of various operational parameters such as contact time, temperature, pH, and dye concentration were studied. The adsorption kinetics was modeled by first-order reversible kinetics, pseudo-first-order kinetics, and pseudo-second-order kinetics. The dye uptake process obeyed the pseudo-second-order kinetic expression at pH 5.7, 7 and 8 whereas the pseudo-first-order kinetic model was fitted well at pH 9. Langmuir, Freundlich and Temkin adsorption models were applied to fit adsorption equilibrium data. The best-fitted data was obtained with the Freundlich model. Thermodynamic study showed that adsorption of CR onto BSC was endothermic in nature and favorable with the positive ΔH o value of 13.613 kJ/mol.

Structural determinants for protein adsorption/non-adsorption to silica surface

International Nuclear Information System (INIS)

Mathe, Christelle; Devineau, Stephanie; Aude, Jean-Christophe; Lagniel, Gilles; Chedin, Stephane; Legros, Veronique; Mathon, Marie-Helene; Renault, Jean-Philippe; Pin, Serge; Boulard, Yves; Labarre, Jean

2013-01-01

The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nano-technology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine) in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many p-p interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption. (authors)

Structural determinants for protein adsorption/non-adsorption to silica surface.

Directory of Open Access Journals (Sweden)

Christelle Mathé

Full Text Available The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nanotechnology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not. If the two protein subsets are large enough, their statistical comparative analysis must reveal the physicochemical determinants relevant for adsorption versus non-adsorption. This methodology was tested with silica nanoparticles. We found that the adsorbed proteins contain a higher number of charged amino acids, particularly arginine, which is consistent with involvement of this basic amino acid in electrostatic interactions with silica. The analysis also identified a marked bias toward low aromatic amino acid content (phenylalanine, tryptophan, tyrosine and histidine in adsorbed proteins. Structural analyses and molecular dynamics simulations of proteins from the two groups indicate that non-adsorbed proteins have twice as many π-π interactions and higher structural rigidity. The data are consistent with the notion that adsorption is correlated with the flexibility of the protein and with its ability to spread on the surface. Our findings led us to propose a refined model of protein adsorption.

Co adsorption in kaolinite

International Nuclear Information System (INIS)

Souza, Eliel S.; Silva, Paulo S.C.

2017-01-01

Adsorption of metal ions in clay minerals has been used as an alternative to water and effluents treatment. Kaolinite is a clay mineral that presents low specific surface area and exchange ion capacity. Nevertheless, structural modifications can be achieved by means of acid or thermal activation. In this paper, it was studied the surface area of kaolinite/bentonite, kaolinite/activated carbon mixtures, thermal activated kaolinite and thermal activated kaolinite/activated carbon mixture. The mixture of kaolinite/activated carbon was tested for pH, contact time, interfering ions and initial concentration effects in the cobalt adsorption. Results showed that the optimized parameters are pH 6 and contact time of 30 min. Chromium acted as a competitive ion, zinc does not appear to have affected adsorption while iron seems to have favored it. Langmuir and Freundlich isotherms indicated that the adsorption of Co in the mixture of kaolinite/activated carbon is a spontaneous process. (author)

Co adsorption in kaolinite

Energy Technology Data Exchange (ETDEWEB)

Souza, Eliel S.; Silva, Paulo S.C., E-mail: eliel201019@hotmail.com, E-mail: pscsilva@ipen.br [Instituto de Pesquisas Energética s e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

Adsorption of metal ions in clay minerals has been used as an alternative to water and effluents treatment. Kaolinite is a clay mineral that presents low specific surface area and exchange ion capacity. Nevertheless, structural modifications can be achieved by means of acid or thermal activation. In this paper, it was studied the surface area of kaolinite/bentonite, kaolinite/activated carbon mixtures, thermal activated kaolinite and thermal activated kaolinite/activated carbon mixture. The mixture of kaolinite/activated carbon was tested for pH, contact time, interfering ions and initial concentration effects in the cobalt adsorption. Results showed that the optimized parameters are pH 6 and contact time of 30 min. Chromium acted as a competitive ion, zinc does not appear to have affected adsorption while iron seems to have favored it. Langmuir and Freundlich isotherms indicated that the adsorption of Co in the mixture of kaolinite/activated carbon is a spontaneous process. (author)

A model for the physical adsorption of atomic hydrogen

NARCIS (Netherlands)

Bruch, L.W.; Ruijgrok, Th.W.

1979-01-01

The formation of the holding potential of physical adsorption is studied with a model in which a hydrogen atom interacts with a perfectly imaging substrate bounded by a sharp planar surface; the exclusion of the atomic electron from the substrate is an important boundary condition in the model. The

Adsorption of a linear polyelectrolyte on a gold electrode

NARCIS (Netherlands)

Barten, D.; Kleijn, J.M.; Cohen Stuart, M.A.

2003-01-01

The adsorption of quaternized poly-2-vinyl pyridine (PVP+), which has a fixed charge per monomer, onto a gold electrode was investigated using reflectometry. The double layer charge and potential of the gold substrate were controlled by means of either the solution pH or by applying an external

Adsorption and co-adsorption of diclofenac and Cu(II) on calcareous soils.

Science.gov (United States)

Graouer-Bacart, Mareen; Sayen, Stéphanie; Guillon, Emmanuel

2016-02-01

Pharmaceuticals are emerging contaminants and their presence in different compartments of the environment has been detected in many countries. In this study, laboratory batch experiments were conducted to characterize the adsorption of diclofenac, a widely used non-steroidal anti-inflammatory drug, on six calcareous soils. The adsorption of diclofenac was relatively low, which may lead to a risk of groundwater contamination and plant uptake. A correlation between the soil-water distribution coefficient Kd and soil characteristics has been highlighted. Indeed, diclofenac adsorption as a function of soil organic matter content (% OM) and Rt=% CaCO3/% OM was successfully described through a simple empirical model, indicating the importance of considering the inhibiting effect of CaCO3 on OM retention properties for a better assessment of diclofenac fate in the specific case of calcareous soils. The simultaneous co-adsorption of diclofenac and copper - a ubiquitous pollutant in the environment - at the water/soil interface, was also investigated. It appeared quite unexpectedly that copper did not have a significant influence on diclofenac retention. Copyright © 2015 Elsevier Inc. All rights reserved.

Adsorption of SO2 on bituminous coal char and activated carbon fiber prepared from phenol formaldehyde

Science.gov (United States)

DeBarr, Joseph A.; Lizzio, Anthony A.; Daley, Michael A.

1996-01-01

Carbon-based materials are used commercially to remove SO2 from coal combustion flue gases. Historically, these materials have consisted of granular activated carbons prepared from lignite or bituminous coal. Recent studies have reported that activated carbon fibers (ACFs) may have potential in this application due to their relatively high SO2 adsorption capacity. In this paper, a comparison of SO2 adsorption for both coal-based carbons and ACFs is presented, as well as ideas on carbon properties that may influence SO2 adsorption

Adsorption of uranium(VI) to manganese oxides: X-ray absorption spectroscopy and surface complexation modeling.

Science.gov (United States)

Wang, Zimeng; Lee, Sung-Woo; Catalano, Jeffrey G; Lezama-Pacheco, Juan S; Bargar, John R; Tebo, Bradley M; Giammar, Daniel E

2013-01-15

The mobility of hexavalent uranium in soil and groundwater is strongly governed by adsorption to mineral surfaces. As strong naturally occurring adsorbents, manganese oxides may significantly influence the fate and transport of uranium. Models for U(VI) adsorption over a broad range of chemical conditions can improve predictive capabilities for uranium transport in the subsurface. This study integrated batch experiments of U(VI) adsorption to synthetic and biogenic MnO(2), surface complexation modeling, ζ-potential analysis, and molecular-scale characterization of adsorbed U(VI) with extended X-ray absorption fine structure (EXAFS) spectroscopy. The surface complexation model included inner-sphere monodentate and bidentate surface complexes and a ternary uranyl-carbonato surface complex, which was consistent with the EXAFS analysis. The model could successfully simulate adsorption results over a broad range of pH and dissolved inorganic carbon concentrations. U(VI) adsorption to synthetic δ-MnO(2) appears to be stronger than to biogenic MnO(2), and the differences in adsorption affinity and capacity are not associated with any substantial difference in U(VI) coordination.

Fibrinogen adsorption on blocked surface of albumin

DEFF Research Database (Denmark)

Holmberg, Maria; Hou, Xiaolin

2011-01-01

We have investigated the adsorption of albumin and fibrinogen onto PET (polyethylene terephthalate) and glass surfaces and how pre-adsorption of albumin onto these surfaces can affect the adsorption of later added fibrinogen. For materials and devices being exposed to blood, adsorption...... of fibrinogen is often a non-wanted event, since fibrinogen is part of the clotting cascade and unspecific adsorption of fibrinogen can have an influence on the activation of platelets. Albumin is often used as blocking agent for avoiding unspecific protein adsorption onto surfaces in devices designed to handle...... energies, the adsorption of both albumin and fibrinogen has been monitored simultaneously on the same sample. Information about topography and coverage of adsorbed protein layers has been obtained using AFM (Atomic Force Microscopy) analysis in liquid. Our studies show that albumin adsorbs in a multilayer...

In Situ Investigation of the Adsorption of Styrene Phosphonic Acid on Cassiterite (110 Surface by Molecular Modeling

Directory of Open Access Journals (Sweden)

Guichen Gong

2017-09-01

Full Text Available Abstract: The flotation, adsorption and bonding mechanisms of styrene phosphonic acid (SPA to cassiterite were studied using microflotation tests, zeta potential measurements, solution chemistry analysis and density functional theory (DFT calculations in this paper. Flotation results demonstrated SPA was an excellent collector for cassiterite which could recover over 85% cassiterite particles with the pH range 4.3–6.06 and 40 mg/L SPA. Zeta potential measurements and solution chemistry analysis revealed the adsorption of SPA was mainly contributed by the chemisorption of the monoanions on cassiterite surfaces. Frontier molecular orbital theory analysis and adsorption energy calculation results proved the monoanion of SPA was able to replace the OH− on cassiterite surfaces. The adsorption structure optimization results confirmed the binuclear complex was the most favorable adsorption configuration of SPA on cassiterite (110 surface. Mulliken population calculations and density of states analysis indicated during the bonding process the Sn3 atom lost electrons to O3 atom, and the bonding interaction between O3 and Sn3 atoms was mainly from the contribution of the 2p orbital of O3 atom and the 5s and 5p orbitals of Sn3 atom.

Cadmium Adsorption on HDTMA Modified Montmorillionite

Directory of Open Access Journals (Sweden)

Mohd. Elmuntasir I. Ahmed

2009-06-01

Full Text Available In this paper the possibility of cadmium removal from aqueous solutions by adsorption onto modified montmorillonite clay is investigated. Batch adsorption experiments performed revealed an enhanced removal of cadmium using HDTMA modified montmorillonite to 100% of its exchange capacity. Modified montmorillonite adsorption capacity increases at higher pHs suggesting adsorption occurs as a result of surface precipitation and HDTMA complex formation due to the fact that the original negatively charged montmorillonite is now covered by a cationic layer of HDTMA. Adsorption isotherms generated followed a Langmuir isotherm equation possibly indicating a monolayer coverage. Adsorption capacities of up to 49 mg/g and removals greater than 90% were achieved. Anionic selectivity of the HDTMA modified monmorillonite is particularly advantageous in water treatment applications where high concentrations of less adsorbable species are present, and the lack of organoclay affinity for these species may allow the available capacity to be utilized selectively by the targeted species.

Adsorption of carbon dioxide in porous magnesium oxides

International Nuclear Information System (INIS)

Gutierrez B, E.

2016-01-01

Mg O powders were synthesized by chemical solution combustion and treated by mechanical milling, and separately were doped with Fe and Ni. The obtained powders were characterized by the X-ray diffraction (DRX) technique, scanning electron microscopy (Sem), elementary semi-quantitative analysis (EDS), N_2 physisorption measurements and infrared spectroscopy (IR). It was studied the CO_2 adsorption capacity in the synthesized materials as a function of temperature, pressure and saturation time. The results show that the CO_2 adsorption capacities on respective materials were 0.39 mmol/g in Mg O powders synthesized by chemical solution combustion, 1.61 mmol/g in Mg O powders treated by mechanical milling during 2.5 h, 0.90 mmol/g in Mg O powders doped with Fe by milling during 2.5 h and 1.50 mmol/g for Mg O powders doped with Ni milling during 7.5 h, at 25 degrees Celsius, 1 atm and 30 min of saturation time. The results showed that the powders treated by mechanical milling are efficient for CO_2 adsorption and are an alternative of advanced materials to be used as potential adsorbent materials and contribute to reduce the global warming. (Author)

Adsorption of heavy metals by road deposited solids.

Science.gov (United States)

Gunawardana, Chandima; Goonetilleke, Ashantha; Egodawatta, Prasanna

2013-01-01

The research study discussed in the paper investigated the adsorption/desorption behaviour of heavy metals commonly deposited on urban road surfaces, namely, Zn, Cu, Cr and Pb, for different particle size ranges of solids. The study outcomes, based on field studies and batch experiments, confirmed that road deposited solids particles contain a significantly high amount of vacant charge sites with the potential to adsorb additional heavy metals. Kinetic studies and adsorption experiments indicated that Cr is the most preferred metal element to associate with solids due to the relatively high electronegativity and high charge density of trivalent cation (Cr(3+)). However, the relatively low availability of Cr in the urban road environment could influence this behaviour. Comparing total adsorbed metals present in solids particles, it was found that Zn has the highest capacity for adsorption to solids. Desorption experiments confirmed that a low concentration of Cu, Cr and Pb in solids was present in water-soluble and exchangeable form, whilst a significant fraction of adsorbed Zn has a high likelihood of being released back into solution. Among heavy metals, Zn is considered to be the most commonly available metal among road surface pollutants.

Graphitic Carbon Materials Tailored for the Rapid Adsorption of Biomolecules

Science.gov (United States)

Pescatore, Nicholas A.

Sepsis is an overactive inflammatory response to an infection, with 19 million cases estimated worldwide and causing organ dysfunction if left untreated. Three pro-inflammatory cytokines are seen from literature review as vital biomarkers for sepsis and are interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha), which have the potential to be removed by hemoperfusion. This thesis examines carbon nanomaterials for their adsorption capabilities in the search for an optimal material for blood cleansing hemoperfusion application, such as mediating the effects of sepsis. Non-porous and porous carbon polymorphs and their properties are investigated in this thesis for their protein adsorption capabilities. Polymer-derived mesoporous carbons were compared to non-porous graphene nanoplatelets (GNP's) to observe changes in adsorption capacity for cytokines between porous and non-porous materials. GNP's were functionalized via high temperature vacuum annealing, air oxidation, acid oxidation and amination treatments to understand the effect of surface chemistry on adsorption. For practical use in a hemoperfusion column, polymer-derived carbon beads and composite materials such as cryogel and PTFE-GNP composites were designed and tested for their adsorption capacity. At concentrations of IL-6, IL-8, and TNF-alpha seen in septic patients, these cytokines were completely removed from the blood after 5 minutes of incubation with GNP's. Overall, a low-cost, scalable carbon adsorbent was found to provide a novel approach of rapidly removing pro-inflammatory cytokines from septic patients.

A Simple Adsorption Experiment

Science.gov (United States)

Guirado, Gonzalo; Ayllon, Jose A.

2011-01-01

The study of adsorption phenomenon is one of the most relevant and traditional physical chemistry experiments performed by chemistry undergraduate students in laboratory courses. In this article, we describe an easy, inexpensive, and straightforward way to experimentally determine adsorption isotherms using pieces of filter paper as the adsorbent…

Application potential of grapefruit peel as dye sorbent: Kinetics, equilibrium and mechanism of crystal violet adsorption

International Nuclear Information System (INIS)

Saeed, Asma; Sharif, Mehwish; Iqbal, Muhammad

2010-01-01

This study reports the sorption of crystal violet (CV) dye by grapefruit peel (GFP), which has application potential in the remediation of dye-contaminated wastewaters using a solid waste generated by the citrus fruit juice industry. Batch adsorption of CV was conducted to evaluate the effect of initial pH, contact time, temperature, initial dye concentration, GFP adsorbent dose, and removal of the adsorbate CV dye from aqueous solution to understand the mechanism of sorption involved. Sorption equilibrium reached rapidly with 96% CV removal in 60 min. Fit of the sorption experimental data was tested on the pseudo-first and pseudo-second-order kinetics mathematical equations, which was noted to follow the pseudo-second-order kinetics better, with coefficient of correlation ≥0.992. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacity of 254.16 mg g -1 . The GFP was regenerated using 1 M NaOH, with up to 98.25% recovery of CV and could be reused as a dye sorbent in repeated cycles. GFP was also shown to be highly effective in removing CV from aqueous solution in continuous-flow fixed-bed column reactors. The study shows that GFP has the potential of application as an efficient sorbent for the removal of CV from aqueous solutions.

Application potential of grapefruit peel as dye sorbent: kinetics, equilibrium and mechanism of crystal violet adsorption.

Science.gov (United States)

Saeed, Asma; Sharif, Mehwish; Iqbal, Muhammad

2010-07-15

This study reports the sorption of crystal violet (CV) dye by grapefruit peel (GFP), which has application potential in the remediation of dye-contaminated wastewaters using a solid waste generated by the citrus fruit juice industry. Batch adsorption of CV was conducted to evaluate the effect of initial pH, contact time, temperature, initial dye concentration, GFP adsorbent dose, and removal of the adsorbate CV dye from aqueous solution to understand the mechanism of sorption involved. Sorption equilibrium reached rapidly with 96% CV removal in 60 min. Fit of the sorption experimental data was tested on the pseudo-first and pseudo-second-order kinetics mathematical equations, which was noted to follow the pseudo-second-order kinetics better, with coefficient of correlation > or = 0.992. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacity of 254.16 mg g(-1). The GFP was regenerated using 1 M NaOH, with up to 98.25% recovery of CV and could be reused as a dye sorbent in repeated cycles. GFP was also shown to be highly effective in removing CV from aqueous solution in continuous-flow fixed-bed column reactors. The study shows that GFP has the potential of application as an efficient sorbent for the removal of CV from aqueous solutions. 2010 Elsevier B.V. All rights reserved.

Application potential of grapefruit peel as dye sorbent: Kinetics, equilibrium and mechanism of crystal violet adsorption

Energy Technology Data Exchange (ETDEWEB)

Saeed, Asma, E-mail: asmadr@wol.net.pk [Environmental Biotechnology Group, Biotechnology and Food Research Centre, PCSIR Laboratories Complex, Ferozepur Road, Lahore 54600 (Pakistan); Sharif, Mehwish [School of Biological Sciences, University of the Punjab, Lahore 54590 (Pakistan); Iqbal, Muhammad [Environmental Biotechnology Group, Biotechnology and Food Research Centre, PCSIR Laboratories Complex, Ferozepur Road, Lahore 54600 (Pakistan)

2010-07-15

This study reports the sorption of crystal violet (CV) dye by grapefruit peel (GFP), which has application potential in the remediation of dye-contaminated wastewaters using a solid waste generated by the citrus fruit juice industry. Batch adsorption of CV was conducted to evaluate the effect of initial pH, contact time, temperature, initial dye concentration, GFP adsorbent dose, and removal of the adsorbate CV dye from aqueous solution to understand the mechanism of sorption involved. Sorption equilibrium reached rapidly with 96% CV removal in 60 min. Fit of the sorption experimental data was tested on the pseudo-first and pseudo-second-order kinetics mathematical equations, which was noted to follow the pseudo-second-order kinetics better, with coefficient of correlation {>=}0.992. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacity of 254.16 mg g{sup -1}. The GFP was regenerated using 1 M NaOH, with up to 98.25% recovery of CV and could be reused as a dye sorbent in repeated cycles. GFP was also shown to be highly effective in removing CV from aqueous solution in continuous-flow fixed-bed column reactors. The study shows that GFP has the potential of application as an efficient sorbent for the removal of CV from aqueous solutions.

Physical adsorption and molecular dynamics

International Nuclear Information System (INIS)

Cohan, N.V.

1981-01-01

Some aspects of noble gases adsorption (except He) on graphite substracts are reviewed. Experimental results from this adsorption are analyzed and compared with molecular dynamics calculations. (L.C.) [pt

Simplified local density model for adsorption over large pressure ranges

International Nuclear Information System (INIS)

Rangarajan, B.; Lira, C.T.; Subramanian, R.

1995-01-01

Physical adsorption of high-pressure fluids onto solids is of interest in the transportation and storage of fuel and radioactive gases; the separation and purification of lower hydrocarbons; solid-phase extractions; adsorbent regenerations using supercritical fluids; supercritical fluid chromatography; and critical point drying. A mean-field model is developed that superimposes the fluid-solid potential on a fluid equation of state to predict adsorption on a flat wall from vapor, liquid, and supercritical phases. A van der Waals-type equation of state is used to represent the fluid phase, and is simplified with a local density approximation for calculating the configurational energy of the inhomogeneous fluid. The simplified local density approximation makes the model tractable for routine calculations over wide pressure ranges. The model is capable of prediction of Type 2 and 3 subcritical isotherms for adsorption on a flat wall, and shows the characteristic cusplike behavior and crossovers seen experimentally near the fluid critical point

La Gran financiarización

Directory of Open Access Journals (Sweden)

Julio Castellanos Elías

2015-05-01

Full Text Available Reseña al libro de Polanyi Levitt, Kari "From The Great Transformation to the Great Financialization. On Karl Polanyi and Other Essays”, Fernwood Publishing, Nova Scotia, Canada, 2013, 286 pp.

Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

International Nuclear Information System (INIS)

Simič, R.; Kalin, M.

2013-01-01

Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

Adsorption mechanisms for fatty acids on DLC and steel studied by AFM and tribological experiments

Energy Technology Data Exchange (ETDEWEB)

Simič, R.; Kalin, M., E-mail: mitjan.kalin@tint.fs.uni-lj.si

2013-10-15

Fatty acids are known to affect the friction and wear of steel contacts via adsorption onto the surface, which is one of the fundamental boundary-lubrication mechanisms. The understanding of the lubrication mechanisms of polar molecules on diamond-like carbon (DLC) is, however, still insufficient. In this work we aimed to find out whether such molecules have a similar effect on DLC coatings as they do on steel. The adsorption of hexadecanoic acid in various concentrations (2–20 mmol/l) on DLC was studied under static conditions using an atomic force microscope (AFM). The amount of surface coverage of the adsorbed fatty-acid molecules was analysed. In addition, tribological tests were performed to correlate the wear and friction behaviours in tribological contacts with the adsorption of molecules on the surface under static conditions. A good correlation between the AFM results and the tribological behaviour was observed. We confirmed that fatty acids can adsorb onto the DLC surfaces and are, therefore, potential boundary-lubrication agents for DLC coatings. The adsorption of the fatty acid onto the DLC surfaces reduces the wear of the coatings, but it is less effective in reducing the friction. Tentative adsorption mechanisms that include an environmental species effect, a temperature effect and a tribochemical effect are proposed for DLC and steel surfaces based on our results and few potential mechanisms found in literature.

Novel adsorptive ultrafiltration membranes derived from polyvinyltetrazole-co-polyacrylonitrile for Cu(II) ions removal

KAUST Repository

Kumar, Mahendra; Shevate, Rahul; Hilke, Roland; Peinemann, Klaus-Viktor

2016-01-01

Novel adsorptive ultrafiltration membranes were manufactured from synthesized polyvinyltetrazole−co−polyacrylonitrile (PVT−co−PAN) by nonsolvent induced phase separation (NIPS). PVT−co−PAN with various degree of functionalization (DF) was synthesized via a [3+2] cycloaddition reaction at 60°C using a commercial PAN. PVT−co−PAN with varied DF was then explored to prepare adsorptive membranes. The membranes were characterized by surface zeta potential and static water contact angle measurements, scanning electron microscopy as well as atomic force microscopy (AFM) techniques. It was shown that PVT segments contributed to alter the pore size, charge and hydrophilic behavior of the membranes. The membranes became more negatively charged and hydrophilic after addition of PVT segments. The PVT segments in the membranes served as the major binding sites for adsorption of Cu(II) ions from aqueous solution. The maximum adsorption of Cu(II) ions by the membranes in static condition and in a continuous ultrafiltration of 10 ppm solution was attained at pH = 5. The adsorption data suggest that the Freundlich isotherm model describes well Cu(II) ions adsorption on the membranes from aqueous solution. The adsorption capacity obtained from the Freundlich isotherm model was 44.3 mg g−1; this value is higher than other membrane adsorption data reported in the literature. Overall, the membranes fabricated from PVT−co−PAN are attractive for efficient removal of heavy metal ions under the optimized conditions.

Novel adsorptive ultrafiltration membranes derived from polyvinyltetrazole-co-polyacrylonitrile for Cu(II) ions removal

KAUST Repository

Kumar, Mahendra

2016-05-04

Novel adsorptive ultrafiltration membranes were manufactured from synthesized polyvinyltetrazole−co−polyacrylonitrile (PVT−co−PAN) by nonsolvent induced phase separation (NIPS). PVT−co−PAN with various degree of functionalization (DF) was synthesized via a [3+2] cycloaddition reaction at 60°C using a commercial PAN. PVT−co−PAN with varied DF was then explored to prepare adsorptive membranes. The membranes were characterized by surface zeta potential and static water contact angle measurements, scanning electron microscopy as well as atomic force microscopy (AFM) techniques. It was shown that PVT segments contributed to alter the pore size, charge and hydrophilic behavior of the membranes. The membranes became more negatively charged and hydrophilic after addition of PVT segments. The PVT segments in the membranes served as the major binding sites for adsorption of Cu(II) ions from aqueous solution. The maximum adsorption of Cu(II) ions by the membranes in static condition and in a continuous ultrafiltration of 10 ppm solution was attained at pH = 5. The adsorption data suggest that the Freundlich isotherm model describes well Cu(II) ions adsorption on the membranes from aqueous solution. The adsorption capacity obtained from the Freundlich isotherm model was 44.3 mg g−1; this value is higher than other membrane adsorption data reported in the literature. Overall, the membranes fabricated from PVT−co−PAN are attractive for efficient removal of heavy metal ions under the optimized conditions.

Adsorptive potential of cationic Basic Yellow 2 (BY2) dye onto natural untreated clay (NUC) from aqueous phase: Mass transfer analysis, kinetic and equilibrium profile

Energy Technology Data Exchange (ETDEWEB)

Öztürk, A.; Malkoc, E., E-mail: emalkoc@atauni.edu.tr

2014-04-01

Highlights: • In this work, natural untreated clay (NUC) was studied for the removal of Basic Yellow 2 (BY2) from aqueous solution in batch system. The effects of initial BY2 concentration, contact time, solution temperature and solution pH on BY2 adsorption were investigated. • In FTIR spectra, various functional groups detected on the surface of NUC before and after adsorption. There are some peaks were shifted, disappeared and new peaks were also detected in the BY2 dye adsorbed NUC. Six significant bands at 3621, 3349, 1651,1608,1435 and 872 cm⁻¹ which indicated the bonds, –OH groups, –NH stretching, C–H and C–C bend group were increased. These six significant bands in the spectrum indicate the possible involvement of the respective functional group on the surface of NUC in BY2 dye adsorption process. • Obtained XRD result suggests that the BY2 dye adsorbed NUC might induce bulk phase changes. • The most probable pore size was about 5 nm, according to pore size distribution, therefore it was regarded as a mesoporous material of NUC. • From BET analysis, the specific BET and Langmuir surface area of NUC was found to be 90.5454 and 123.1516 m²/g with corresponding total pore volume of 0.1155 cm³/g (P/P₀ = 0.98). Micropore volume and micropore surface area were calculated using the t-plot method. The micropore surface area, calculated by the t-plot method, was 23.544 m²/g for NUC. • Pseudo-second-order kinetic model fits the adsorption process accurately. The Langmuir isotherm model was well described by the equilibrium data with maximum adsorption capacity of 833.33 mg/g at 25 °C. From Boyd plot, the adsorption of BY2 on NUC took place by film diffusion mechanism. Thermodynamic calculation indicated that the adsorption process was spontaneous and exothermic. Abstract: In this work, natural untreated clay (NUC) was studied for the removal of Basic Yellow 2 (BY2) from aqueous solution in batch system. The effects of initial BY2

Simultaneous oxidation and adsorption of As(III) from water by cerium modified chitosan ultrafine nanobiosorbent

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lingfan [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Zhu, Tianyi [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Liu, Xin, E-mail: liuxin@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Wenqing, E-mail: zhwqing@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2016-05-05

Highlights: • A novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) was prepared. • The Ce-CNB possessed properties for simultaneous oxidation and adsorption As(III). • Adsorption of As(III) by Ce-CNB was in high efficiency. • Mechanisms for As(III) adsorption on Ce-CNB were elucidated. - Abstract: Since most existing arsenic removal adsorbents are difficult to effectively remove arsenite (As(III)), an urgent need is to develop an efficient adsorbent for removing As(III) from contaminated water. In this study, a novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) with simultaneous oxidation and adsorption As(III) performance has been successfully developed. The resulting Ce-CNB with or without As(III) adsorption was characterized by FTIR, XRD, SEM, EDS, TEM, EMI and XPS analysis. Batch of adsorption experiments were performed to investigate the effects of various conditions on the As(III) adsorption. The adsorption behaviors were well described by the Langmuir isotherm and the pseudo-second-order kinetic model, with the maximum adsorption capacities of 57.5 mg g{sup −1}. The adsorption mechanisms for As(III) were (i) formed monodentate and bidentate complexes between hydroxyl groups and arsenite; and (ii) partial As(III) oxidized to As(V) followed by simultaneously adsorbed on the surface of Ce-CNB. This novel nanocomposite can be reused while maintaining a high removal efficiency and can be applied to treat 5.8 L of As(III)-polluted water with the effluent concentration lower than the World Health Organization standard, which suggests its great potential to remove As(III) from contaminated water.

Preparation, Characterization and Adsorption Evaluation of old Newspaper Fibres using Basket Reactor (Nickel Removal by Adsorption)

International Nuclear Information System (INIS)

Ossman, M. E.; Abdelfatah, M.; Kiros, Y.

2016-01-01

In this work, old newspaper fibers bleached with H 2 O 2 , treated with KOH and treated with NaOCl were investigated as potential adsorbents. The characterization of the produced fibers using FTIR, SEM and particle size distribution have been carried out and tested for the removal of Ni (II) from aqueous solutions. The results indicated that the fibers treated with KOH give the highest %removal of Ni (II) with 88%. Two different reactor designs (batch and basket reactor) with different variables were studied. The results indicated that the equilibrium time was 30 min. and the removal of Ni (II) increased significantly as the p H increased from 2.0 to 6.0 and decreased at p H range of 6.5–8.0. The adsorption of Ni (II) onto old newspaper fibers treated with KOH using batch and basket reactors follows the Langmuir isotherm. The pseudo second order kinetic model provided good correlation for the adsorption of Ni (II) onto old newspaper fibers treated with KOH for both batch and basket reactors.

Removal of mercury by adsorption: a review.

Science.gov (United States)

Yu, Jin-Gang; Yue, Bao-Yu; Wu, Xiong-Wei; Liu, Qi; Jiao, Fei-Peng; Jiang, Xin-Yu; Chen, Xiao-Qing

2016-03-01

Due to natural and production activities, mercury contamination has become one of the major environmental problems over the world. Mercury contamination is a serious threat to human health. Among the existing technologies available for mercury pollution control, the adsorption process can get excellent separation effects and has been further studied. This review is attempted to cover a wide range of adsorbents that were developed for the removal of mercury from the year 2011. Various adsorbents, including the latest adsorbents, are presented along with highlighting and discussing the key advancements on their preparation, modification technologies, and strategies. By comparing their adsorption capacities, it is evident from the literature survey that some adsorbents have shown excellent potential for the removal of mercury. However, there is still a need to develop novel, efficient adsorbents with low cost, high stability, and easy production and manufacture for practical utility.

Management of agricultural waste for removal of heavy metals from aqueous solution: adsorption behaviors, adsorption mechanisms, environmental protection, and techno-economic analysis.

Science.gov (United States)

Elhafez, S E Abd; Hamad, H A; Zaatout, A A; Malash, G F

2017-01-01

In the last decades, Egypt has been suffering from the phenomenon of black cloud resulting from burning rice husk and increasing the demand for water leading to the water crisis. An alternative, low-value and surplus agricultural byproduct (rice husk, RH) has an enormous potential for the removal of Cu(II) ions from water. The present study focuses on the chance of the use of rice husk as a bio-adsorbent without any chemical treatment instead of burning it and soiling the environment. The elemental, structural, morphological, surface functional, thermal, and textural characteristics of RH are determined by XRF, XRD, SEM, FT-IR, TGA, and BET surface area, respectively, and contributed to the understanding of the adsorption mechanism of Cu(II) ions in aqueous solution. Also, the performance analysis, adsorption mechanism, influencing factors, favorable conditions, etc. are discussed in this article. The results obtained from optimization by batch mode are achieved under the following conditions: initial concentration, 150 ppm; amount of rice husk, 1 g; average particle size, 0.25 mm; temperature, 25 °C; pH, 4; agitation rate, 180 rpm; and contact time, 60 min. RH exhibits a high degree of selectivity for Cu(II) adsorption. The adsorption isotherm is fitted well with Langmuir and Freundlich models with R 2 0.998 and 0.997, respectively. The adsorption is well governed by the pseudo-second-order kinetics. It is observed that the rate of adsorption improves with decreasing temperature, and the process is exothermic and non-spontaneous. Particular attention has being paid to factors as production processes, fixed/operational cost, production cost, and profit. The techno-economical analysis is presented in this study that provides precise demands on capital for a fixed investment, provisions for operational capital, and finally provisions for revenue. The social, economical, and environmental benefits by industrial point of view using low-cost adsorbent are also

Adsorption of gas mixtures on heterogeneous solid surfaces

Energy Technology Data Exchange (ETDEWEB)

Jaroniec, M; Rudzinski, W

1977-01-01

A review of theoretical studies on the physical adsorption from gas mixtures on heterogeneous solid surfaces, mainly by Jaroniec and coworkers, covers the vector notation used in the calculations; adsorption isotherms for multicomponent gases; the generalized integral equation for adsorption of gas mixtures, its numerical and analytical solutions, applied, (e.g., to interpret the experimental adsorption isotherms of ethane/ethylene on Nuxit-AL); thermodynamic relations, applied, (e.g., to calculating isosteric adsorption heats from experimental parameters for the adsorption of propylene from propane/propylene mixtures on Nuxit-AL); and the derivation and use of a simplified integral equation for describing the adsorption from gas mixtures on heterogeneous surfaces. 75 references.

A biological oil adsorption filter

International Nuclear Information System (INIS)

Pasila, A.

2005-01-01

A new oil adsorption method called adsorption filtration (AF) has been developed. It is a technology where by oil residues can be cleaned from water by running it through a simple filter made from freeze treated, dried, milled and then fragmented plant material. By choosing suitable plants and fragmentation sizes it is possible to produce filters, which pass water but adsorb oil. The aim of this study was to investigate the possibilities of manufacturing oil adsorbing filter materials from reed canary grass (Phalaris arundinacea), flax (Linum usitatissimum L.) or hemp fibre (Cannabis sativa L.). The oil (80 ml) was mixed with de-ionised water (200 ml) and this mixture was filtered through 10 or 20 g adsorption filters. Fine spring harvested hemp fibre (diameter less than 1 mm) and reed canary grass fragments adsorb 2-4 g of oil per gram of adsorption material compared to 1-3 g of water. Adsorption filtration is thus a novel way of gathering spilled oil in shallow coastal waters before the oil reaches the shore. (author)

A biological oil adsorption filter

Energy Technology Data Exchange (ETDEWEB)

Pasila, A [University of Helsinki (Finland). Dept. of Agricultural Engineering and Household Technology

2005-12-01

A new oil adsorption method called adsorption filtration (AF) has been developed. It is a technology where by oil residues can be cleaned from water by running it through a simple filter made from freeze treated, dried, milled and then fragmented plant material. By choosing suitable plants and fragmentation sizes it is possible to produce filters, which pass water but adsorb oil. The aim of this study was to investigate the possibilities of manufacturing oil adsorbing filter materials from reed canary grass (Phalaris arundinacea), flax (Linum usitatissimum L.) or hemp fibre (Cannabis sativa L.). The oil (80 ml) was mixed with de-ionised water (200 ml) and this mixture was filtered through 10 or 20 g adsorption filters. Fine spring harvested hemp fibre (diameter less than 1 mm) and reed canary grass fragments adsorb 2-4 g of oil per gram of adsorption material compared to 1-3 g of water. Adsorption filtration is thus a novel way of gathering spilled oil in shallow coastal waters before the oil reaches the shore. (author)

Temperature and pH influence adsorption of cellobiohydrolase onto lignin by changing the protein properties.

Science.gov (United States)

Lu, Xianqin; Wang, Can; Li, Xuezhi; Zhao, Jian

2017-12-01

Non-productive adsorption of cellulase onto lignin restricted the movement of cellulase and also hindered the cellulase recycling in bioconversion of lignocellulose. In this study, effect of temperature and pH on adsorption and desorption of cellobiohydrolase (CBH) on lignin and its possible mechanism were discussed. It found that pH value and temperature influenced the adsorption and desorption behaviors of CBH on lignin. Different thermodynamic models suggested that the action between lignin and CBH was physical action. More CBH was adsorbed onto lignin, but lower initial adsorption velocity was detected at 50°C comparing with 4°C. Elevating pH value could improve desorption of cellulase from lignin. The changes of hydrophobicity and electric potential on protein surface may partially explain the impact of environmental conditions on the adsorption and desorption behaviors of CBH on lignin, and comparing to electrical interaction, the hydrophobicity may be the dominating factor influencing the behaviors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption behavior and mechanism of Cr(VI) using Sakura waste from aqueous solution

International Nuclear Information System (INIS)

Qi, Wenfang; Zhao, Yingxin; Zheng, Xinyi; Ji, Min; Zhang, Zhenya

2016-01-01

Graphical abstract: The main chemical components of Sakura leaves are cellulose 16.6%, hemicellulose 10.4%, lignin 18.3%, ash 11.4%, and others 43.3%. The adsorption capacity of Cr(VI) onto Sakura leaves can achieve 435.25 mg g"−"1, much higher than other similar agroforestry wastes. - Highlights: • Sakura leaves were prepared to remove Cr(VI) from aqueous solution. • The maximum adsorption capacity of Cr(VI) reached 435.25 mg g"−"1. • Cr(VI) adsorption fitted pseudo-second-order kinetic model. • Isotherm models indicated Cr(VI) adsorption occurred on a monolayer surface. • The influence order of coexisting ions followed PO_4"3"− > SO_4"2"− > Cl"−. - Abstract: A forestall waste, Sakura leave, has been studied for the adsorption of Cr(VI) from aqueous solution. The materials before and after adsorption were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). To investigate the adsorption performance of Sakura waste, batch experiments were conducted under different adsorbent dosage, contact time, initial concentration of Cr(VI), and co-existing ions. Results showed the data fitted pseudo-second-order better than pseudo-first-order kinetic model. Equilibrium data was analyzed with Langmuir, Freundlich and Redlich–Peterson isotherm models at temperature ranges from 25 °C to 45 °C. The maximum adsorption capacity from the Langmuir model was 435.25 mg g"−"1 at pH 1.0. The presence of Cl"−, SO_4"2"− and PO_4"3"− would lead to an obvious negative effect on Cr(VI) adsorption, and their influence order follows PO_4"3"− > SO_4"2"− > Cl"−. The study developed a new way to reutilize wastes and showed a great potential for resource recycling.

ADSORPTION AND RELEASING PROPERTIES OF BEAD CELLULOSE

Institute of Scientific and Technical Information of China (English)

A. Morales; E. Bordallo; V. Leon; J. Rieumont

2004-01-01

The adsorption of some dyes on samples of bead cellulose obtained in the Unit of Research-Production "Cuba 9"was studied. Methylene blue, alizarin red and congo red fitted the adsorption isotherm of Langmuir. Adsorption kinetics at pH = 6 was linear with the square root of time indicating the diffusion is the controlling step. At pH = 12 a non-Fickian trend was observed and adsorption was higher for the first two dyes. Experiments carried out to release the methylene blue occluded in the cellulose beads gave a kinetic behavior of zero order. The study of cytochrome C adsorption was included to test a proteinic material. Crosslinking of bead cellulose was performed with epichlorohydrin decreasing its adsorption capacity in acidic or alkaline solution.

Adsorption behavior of carboxylated cellulose nanocrystal—polyethyleneimine composite for removal of Cr(VI) ions

Energy Technology Data Exchange (ETDEWEB)

Liu, Chao; Jin, Ru-Na; Ouyang, Xiao-kun, E-mail: xkouyang@zjou.edu.cn; Wang, Yang-Guang

2017-06-30

-PEI was a spontaneous exothermic process. Regeneration tests indicated that CCN-PEI showed good durability and good efficiency for repeated Cr(VI) adsorptions. Based on the results obtained in this work, it can be concluded that CCN-PEI is a potentially effective adsorbent for removing Cr(VI) ions from aqueous solutions.

Study of polyethyleneimine- and amidoxime-functionalized hybrid biomass of Spirulina (Arthrospira) platensis for adsorption of uranium (VI) ion.

Science.gov (United States)

Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

2015-11-01

This study investigates the potential application of the polyethyleneimine- (PEI) and amidoxime-modified Spirulina (Arthrospira) platensis biomasses for the removal of uranium ion in batch mode using the native biomass as a control system. The uranium ion adsorption was also characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra, zeta potential analysis, and surface area measurement studies. The effects of pH, biomass amount, contact time, initial uranium ion concentration, and ionic strength were evaluated by using native and modified algal biomass preparations. The uranium ion removal was rapid, with more than 70% of total adsorption taking place in 40 min, and equilibrium was established within 60 min. From the experimental data, it was found that the amount of adsorption uranium ion on the algal preparations decreased in the following series: amidoxime-modified algal biomass > PEI-modified algal biomass > native algal biomass. Maximum adsorption capacities of amidoxime- and PEI-modified, and native algal biomasses were found to be 366.8, 279.5, and 194.6 mg/g, respectively, in batchwise studies. The adsorption rate of U(VI) ion by amidoxime-modified algal biomass was higher than those of the native and PEI-modified counterparts. The adsorption processes on all the algal biomass preparations followed by the Dubinin-Radushkevitch (D-R) and Temkin isotherms and pseudo-second-order kinetic models. The thermodynamic parameters were determined at four different temperatures (i.e., 15, 25, 35, and 45 °C) using the thermodynamics constant of the Temkin isotherm model. The ΔH° and ΔG° values of U(VI) ion adsorption on algal preparations show endothermic heat of adsorption; higher temperatures favor the process. The native and modified algal biomass preparations were regenerated using 10 mM HNO3. These results show that amidoxime-modified algal biomass can be a potential candidate for effective removal of U(VI) ion from

Radon adsorption on present activated charcoals

International Nuclear Information System (INIS)

Kazankin, Yu.N.; Trofimov, A.M.; Mikhajlova, L.K.

1978-01-01

Radon adsorption from helium and air has been studied on modern activated carbons of SKT-1, SKT-2a, SKT-3, SKT-2b, SKT-6, PAU-1 within the temperature range from 100 to 80 deg. It has been shown that PAU-1 carbon has the highest activity with respect to radon in the temperature range studied. With decreasing temperature the adsorption coefficients increase sharply. It has been found that for the case of radon adsorption from helium the logarythm of the Henry coefficient linearly depends on the inverse value of absolute temperature. Adsorption of radon from air is inhibited and the above-cited relationship is deviated from linear. The results of calculating differential heats of radon and air adsorption as well as coefficients of radon and air separation on carbons are presented

Adsorption of methyl iodide on charcoal

International Nuclear Information System (INIS)

Hidajat, K.; Aracil, J.; Kenney, C.N.

1990-01-01

The adsorption of non-radioactive methyl iodide has been measured experimentally over a range of conditions of concentration, and temperature on an activated charcoal. This is of interest since methyl iodide is formed from iodine fission products in gas cooled nuclear reactors. A mathematical model has also been developed which describes the rate of adsorption, under isothermal and linear adsorption isotherm conditions in a recycle adsorber. This model takes into account the resistance to adsorption caused by the surface adsorption, as well as the external and internal mass transfer resistances. The solution to the model for the recycle adsorber was obtained using a semidiscretisation method to reduce the partial differential equations to a system of stiff ordinary differential equations, and the resulting differential equations solved by a standard numerical technique. (author)

Enhanced adsorption of ionizable antibiotics on activated carbon fiber under electrochemical assistance in continuous-flow modes.

Science.gov (United States)

Wang, Sitan; Li, Xiaona; Zhao, Huimin; Quan, Xie; Chen, Shuo; Yu, Hongtao

2018-05-01

Ionizable antibiotics have attracted serious concerns because of their variable dissociation forms and thereby rendering unique toxicity and microorganism resistance. Developing an efficient and environmentally friendly method for removing these micropollutants from environmental media remains very challenging. Here, electro-assisted adsorption onto activated carbon fiber in continuous-flow mode was used to remove three ionizable antibiotics, sulfadimethoxine (SDM), ciprofloxacin (CIP), and clarithromycin (CLA), from water. Benefiting from strengthened electrostatic interactions, the adsorption capacities for the target antibiotics (10 mg/L) in flow mode (70.9-202.2 mg/g) increased by ∼5 times under a potential of 1.0 V (SDM) or -1.0 V (CIP and CLA) relative to those of open circuit (OC) adsorption. Meanwhile, effluent concentration decreased from >100 μg/L to 9.6 μg/L with removal efficiency increasing from 99.0% to 99.9%. Moreover, high recovery efficiency of ACF up to 96.35 ± 0.65% was achieved by imposing a reverse potential (-1.0 V) relative to that used for SDM adsorption. In addition, trace levels of antibiotics (364-580 ng/L) in surface water could be removed effectively to achieve low effluent concentration (0.4-1.2 ng/L) and high removal efficiency (99.9%) upon treating up to ∼1560 bed volumes (BVs), demonstrating the potential of electro-assisted adsorption for practical application in water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adsorption thermal energy storage for cogeneration in industrial batch processes: Experiment, dynamic modeling and system analysis

International Nuclear Information System (INIS)