Influence of gypsum on efflorescence in ceramic tiles

International Nuclear Information System (INIS)

Monteiro, C.M.O.L.; Nascimento, R.M.; Martinelli, A.E.

2009-01-01

The red ceramic industry is recognized as of major importance in Piaui State. The State capital, Teresina, is the greatest producer of this material, which is used mainly for masonry sealing blocks. One of the most frequent problems in this kind of products is the efflorescence.This paper has the main objective of studying the influence of gypsum on tiles, using the local industry production standards. The raw materials were characterized by FRX, DRX, thermal analysis and sulfates. Extruded test specimens were made with the addition of 1%, 3% and 5% of gypsum in the ceramic paste, burned at 850 deg C, 950 deg C and 1050 deg C and submitted to further technological and analysis for MEV. The reference ceramic paste did not show tendency to efflorescence formation after burning for samples with 1% gypsum added to the paste. The reference ceramic paste showed tendency to efflorescence formation after drying and consolidated efflorescence after burning for samples with 5% gypsum added to the paste. (author)

Gypsum karst in Great Britain

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Cooper A.H.

1996-01-01

Full Text Available In Great Britain the most spectacular gypsum karst development is in the Zechstein gypsum (late Permian mainly in north-eastern England. The Midlands of England also has some karst developed in the Triassic gypsum in the vicinity of Nottingham. Along the north-east coast, south of Sunderland, well-developed palaeokarst, with magnificent breccia pipes, was produced by dissolution of Permian gypsum. In north-west England a small gypsum cave system of phreatic origin has been surveyed and recorded. A large actively evolving phreatic gypsum cave system has been postulated beneath the Ripon area on the basis of studies of subsidence and boreholes. The rate of gypsum dissolution here, and the associated collapse lead to difficult civil engineering and construction conditions, which can also be aggravated by water abstraction.

Suitability of Gypsum for the Production of Gypsum Plaster an Example from the Abu-Ruweis Evaporites (Upper Triassic), as Subayhi Area, Northwest Jordan

International Nuclear Information System (INIS)

Saqqa, W.; Arikat, M.

2003-01-01

The gypsum of Abu Ruweis Formation (Upper Triassic) of the northwestern Jordan was chemically, physically and mechanically assessed for likely industrial uses. Chemical results indicate that the investigated gypsum (calcium sulfate dihydrate) is highly pure. This is confirmed by the high ratios of CaO (32-33%) andSO 3 (41-43%) and the very low content of other elements such as Mg, Al and Si. Trace elements are also negligible. The CaSO 4 % (86-88%), purity ratio (CaO/SO 3 ) (0.85) , and combined water (≅5%) for β-hemihydrate gypsum agree well with the jordanian standards for gypsum plaster. Thermal analyses indicate that the temperature required to obtain hemihydrate gypsum falls between 175deg-200deg. A significant mass variation or maximum loss on weight (-20%) was achieved after initial dehydration by heating to 200deg. Heating to 225deg is far enough to evolve all combined water molecules. The results of fineness, consistency, setting time, compressive strength and flexural strength for β-hemilhydrate agree, in most of the case, with the local and international standards intended for gypsum building components. The study showed that the absorption and consistency ratios for final gypsum product are proportional to porosity, whilst the consistency itself decreases with the increase of applied stresses. (author)

Hydrogen sulfide release from dairy manure storages containing gypsum bedding

Science.gov (United States)

Recycled gypsum products can provide a cost-effective bedding alternative for dairy producers. Manufacturers report reduced odors, moisture and bacteria in the stall environment when compared to traditional bedding. Gypsum provides a sulfate source that can be converted to hydrogen sulfide under ana...

CHEMICAL SOIL ATTRIBUTES AS AFFECTED BY LIME AND GYPSUM SURFACE APPLICATION

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A. Mantovani

2017-10-01

Full Text Available The gypsum is a soil condition end it has to function contribute to the elimination or reduction of aluminum in the soil in depth. Still, it can contribute to the distribution of nutrients in the soil profile more uniformly and thus increasing the productivity of crops. This study aimed to evaluate the influence of gypsum application, with and without lime, on soil chemical properties and soybean yield, in a no-till system. The experiment was carried in Campos Novos, Santa Catarina State, Brazil, with a randomized block design and split plot design with four replications, the main portion was distributed gypsum doses (1000, 2000, 4000 and 6000 kg ha-1 without incorporation, and the split plot (with and without lime and the liming was 2,000 kg ha-1. We evaluated the performance of components and productivity of soybeans. It was also analyzed the soil pH and Ca, Mg, S and Al at 0-20 and 20-40 cm. The application of gypsum at the rates tested surface with and without lime did not affect the yield components and soybean productivity. At 0-20 cm soil depth lime application increased soil pH by 0.3 units on the average rates of gypsum, but in the 20-40 cm layer was not found effect of lime and gypsum in pH ground due to the short time between application and evaluation. In areas with and without lime contents of Ca and S in the two layers evaluated increased with increasing rates of gypsum, since Mg has difference with the lime application on a 0-20 cm to dose 4000 kg ha-1 and the lime in the gypsum rates and Al decreased with increasing dose gypsum average in the 20-40 cm layer depth. The application of gypsum and limestone softened the negative effects of soil acidity and the increase mainly of calcium and sulfur at 0-20 cm, with less efficient effects in the 20-40 cm layer due to the soil is clayey and the period between the implementation and evaluation be 120 days.

Evaluation of potential for mercury volatilization from natural and FGD gypsum products using flux-chamber tests.

Science.gov (United States)

Shock, Scott S; Noggle, Jessica J; Bloom, Nicholas; Yost, Lisa J

2009-04-01

Synthetic gypsum produced by flue-gas desulfurization (FGD) in coal-fired power plants (FGD gypsum) is put to productive use in manufacturing wallboard. FGD gypsum wallboard is widely used, accounting for nearly 30% of wallboard sold in the United States. Mercury is captured in flue gas and thus is one of the trace metals present in FGD gypsum; raising questions about the potential for mercury exposure from wallboard. Mercury is also one of the trace metals present in "natural" mined gypsum used to make wall board. Data available in the literature were not adequate to assess whether mercury in wallboard from either FGD or natural gypsum could volatilize into indoor air. In this study, mercury volatilization was evaluated using small-scale (5 L) glass and Teflon flux chambers, with samples collected using both iodated carbon and gold-coated sand traps. Mercury flux measurements made using iodated carbon traps (n=6) were below the detection limit of 11.5 ng/m2-day for all natural and synthetic gypsum wallboard samples. Mercury flux measurements made using gold-coated sand traps (n=6) were 0.92 +/- 0.11 ng/m2-day for natural gypsum wallboard and 5.9 +/- 2.4 ng/m2-day for synthetic gypsum wallboard. Room air mercury concentrations between 0.028 and 0.28 ng/m3 and between 0.13 and 2.2 ng/m3 were estimated based on the flux-rate data for natural and synthetic gypsum wallboard samples, respectively, and were calculated assuming a 3 m x 4 m x 5 m room, and 10th and 90th percentile air exchange rates of 0.18/hour and 1.26/hour. The resulting concentration estimates are well below the U.S. Environmental Protection Agency (EPA) reference concentration for indoor air elemental mercury of 300 ng/m3 and the Agency for Toxic Substances and Disease Registry minimal risk level (MRL) of 200 ng/m3. Further, these estimates are below background mercury concentrations in indoor air and within or below the range of typical background mercury concentrations in outdoor air.

Growth of indoor fungi on gypsum.

Science.gov (United States)

Segers, F J J; van Laarhoven, K A; Wösten, H A B; Dijksterhuis, J

2017-08-01

To have a better understanding of fungal growth on gypsum building materials to prevent indoor fungal growth. Gypsum is acquired by mining or as a by-product of flue-gas desulphurization or treatment of phosphate ore for the production of fertilizer. Natural gypsum, flue-gas gypsum and phosphogypsum therefore have different mineral compositions. Here, growth of fungi on these types of gypsum was assessed. Conidia of the indoor fungi Aspergillus niger, Cladosporium halotolerans and Penicillium rubens were inoculated and observed using microscopic techniques including low-temperature scanning electron microscopy. Elemental analysis of gypsum was done using inductively coupled plasma atomic emission spectroscopy and segmented flow analysis. Moisture content of the gypsum was determined using a dynamic vapour sorption apparatus. Aspergillus niger, C. halotolerans and P. rubens hardly germinated on natural gypsum and flue-gas gypsum. The latter two fungi did show germination, outgrowth, and conidiation on phosphogypsum, while A. niger hardly germinated on this substrate. Other experiments show that C. halotolerans and P. rubens can develop in pure water, but A. niger does not. The observations show that the lack of germination of three indoor fungi is explained by the low amount of phosphor in natural, flue-gas and laboratory-grade gypsum. Additionally, C. halotolerans and P. rubens can develop in pure water, while conidia of A. niger do not show any germination, which is explained by the need for organic molecules of this species to induce germination. Indoor fungal growth is a potential threat to human health and causes damage to building materials. This study possibly helps in the application of the right type of gypsum in buildings. © 2017 The Society for Applied Microbiology.

Effects of gypsum on trace metals in soils and earthworms

Science.gov (United States)

Mined gypsum has been beneficially used for many years as an agricultural amendment. Currently a large amount of flue gas desulfurization (FGD) gypsum is produced by removal of SO2 from flue gas streams when fuels with high S content are burned. The FGD gypsum, similar to mined gypsum, can enhance c...

Petroleum Sludge as gypsum replacement in cement plants: Its Impact on Cement Strength

Science.gov (United States)

Benlamoudi, Ali; Kadir, Aeslina Abdul; Khodja, Mohamed

2017-08-01

Due to high cost of cement manufacturing and the huge amount of resources exhaustion, companies are trying to incorporate alternative raw materials or by-products into cement production so as to produce alternative sustainable cement. Petroleum sludge is a dangerous waste that poses serious imparts on soil and groundwater. Given that this sludge contains a high percentage of anhydrite (CaSO4), which is the main component of gypsum (CaSO4.2H2O), it may play the same gypsum role in strength development. In this research, a total replacement of gypsum (100%) has been substituted by petroleum sludge in cement production and has led to an increase of 28.8% in UCS values after 28 curing days. Nevertheless, the burning of this waste has emitted a considerable amount of carbon monoxide (CO) gas that needs to be carefully considered prior to use petroleum sludge within cement plants.

The effect of gypsum products and separating materials on the typography of denture base materials.

Science.gov (United States)

Firtell, D N; Walsh, J F; Elahi, J M

1980-09-01

The typography of polymethyl methacrylate processed against various gypsum products coated with various separating materials was studied under an SEM. Tinfoil and two commercial tin foil substitutes were used as separating material during processing, and the surfaces of the resulting acrylic resin forms were studied for topographical differences. Tinfoil and alpha 2 hemihydrates produced the smoothest surfaces. As a practical solution, a good quality tinfoil substitute and alpha 1 hemihydrate could be used when processing polymethyl methacrylate resin.

Converting SDAP into gypsum in a wet limestone scrubber

Energy Technology Data Exchange (ETDEWEB)

Fogh, F [Faelleskemikerne, Elsamprojekt A/S, Fredericia (Denmark)

1996-12-01

The ELSAM power pool has an installed electrical capacity of approx. 5 GW{sub e}, mainly firing import coal. The major base load units are equipped with desulphurization units and three different desulphurization technologies are used: the wet limestone gypsum process, the spray dry absorption process and a sulphuric acid process. Gypsum and sulphuric acid are commercialized, whereas it has been difficult to utilize the spray dry absorption product (SDAP). The main constituents of SDAP are calcium sulphide, calcium chloride, hydrated lime and impurities mainly originating from fly ash. Sulphide can be oxidized into sulphate in acidic solution - the reaction is utilized in the wet limestone gypsum process - and the possibility of using any spare capacity in the wet limestone gypsum units to oxidize the sulphide content of SDAP into sulphate and produce usable gypsum has been investigated in the laboratory and in a 400 MW{sub e} equivalent wet limestone unit. The limestone inhibition effect of the addition of SDAP is currently being studied in the laboratory in order to determine the effect of different SDAP types (plant/coal sources) on limestone reactivity before further long-term full-scale tests are performed and permanent use of the process planned. (EG)

Synthesis on research results of FGD gypsum briquetting

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Kosturkiewicz Bogdan

2017-01-01

Full Text Available FGD gypsum products can be characterized by significant solubility in water and dusting in dry state. These characteristics can cause a considerable pollution of air, water and soil. Among many approaches of preparing utilization of this waste, the process of compaction using briquetting has proved to be very effective. Using FGD gypsum products a new material of fertilizers characteristics has been acquired and this material is resistant to the conditions of transportation. This paper presents results of experimental briquetting of flue gas desulphurisation products in a roll press. The experiments were conducted in a laboratory roll presses LPW 450 and LPW 1100 equipped with two interchangeable forming rings that form material into saddle-shaped briquettes with volume 6,5 cm3 and 85 cm3. The experiments were conducted with various percentage amounts of FGD gypsum moisture. The results provided information regarding influence of moisture and roll press configuration on quality of briquettes. On the basis of obtained results, technological process and a general outline of technological line for FGD gypsum were developed. Two roll presses of own construction with different outputs were identified as appropriate for this purpose. A range of necessary works related to their adaptation for the FGD gypsum briquetting were pointed out.

The production of hydroxyapatite prototypes from solid bodies of Gypsum/Polyvinyl Alcohol composites

Energy Technology Data Exchange (ETDEWEB)

Barbosa, Amanda Alves; Ferraz, Andrea de Vasconcelos; Dantas, Alan Christie; Olivier, Nelson Cardenas, E-mail: andrea.ferraz@univasf.edu.br [Universidade Federal do Vale do Sao Francisco (UNIVASF), Juazeiro, BA (Brazil)

2014-08-15

Prototypes of porous hydroxyapatite (HAp) were produced from Gypsum/PVA composite, using a mass proportion of 15% polymer. The material was obtained by means of chemical conversion in (NH{sub 4}){sub 2}HPO{sub 4} 0.5 mol.L{sup -1} solution and NH{sub 4}OH 6.0 mol.L{sup -1} alkaline medium for pH control, maintained between 6.0 and 9.0. The reaction occurred at a temperature of 100°C at different test times. The obtained HAp was characterized by several techniques, such as FTIR, which identified the SO{sub 4}{sup 2-} groups characteristic for the Gypsum block, and the PO{sub 4}{sup 2-} groups that are attributed to the biomaterial HAp, besides XRD and SEM, which made it possible to confirm a successful conversion of the material. Tests for mechanical resistance to compression (σ{sub c}) were carried out for both materials as well. (author)

Influence of gypsum on efflorescence in ceramic tiles; Influence da gipsita no surgimento de eflorescencia em telhas ceramicas

Energy Technology Data Exchange (ETDEWEB)

Monteiro, C.M.O.L. [Servico Nacional de Aprendizagem Industrial (SENAI), Teresina, PI (Brazil); Nascimento, R.M.; Martinelli, A.E. [Universidade Federal do Rio Grande do Norte (PPgCEM/UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

2009-07-01

The red ceramic industry is recognized as of major importance in Piaui State. The State capital, Teresina, is the greatest producer of this material, which is used mainly for masonry sealing blocks. One of the most frequent problems in this kind of products is the efflorescence.This paper has the main objective of studying the influence of gypsum on tiles, using the local industry production standards. The raw materials were characterized by FRX, DRX, thermal analysis and sulfates. Extruded test specimens were made with the addition of 1%, 3% and 5% of gypsum in the ceramic paste, burned at 850 deg C, 950 deg C and 1050 deg C and submitted to further technological and analysis for MEV. The reference ceramic paste did not show tendency to efflorescence formation after burning for samples with 1% gypsum added to the paste. The reference ceramic paste showed tendency to efflorescence formation after drying and consolidated efflorescence after burning for samples with 5% gypsum added to the paste. (author)

Gypsum ground: a new occurrence of gypsum sediment in playas of central Australia

Science.gov (United States)

Xiang Yang Chen; Bowler, James M.; Magee, John W.

1991-06-01

There are many playas (dry salt lakes) in arid central Australia (regional rainfall about 250 mm/y and pan evaporation around 3000 mm/y). Highly soluble salts, such as halite, only appear as a thin (several centimetres thick), white, ephemeral efflorescent crust on the dry surface. Gypsum is the major evaporite precipitating both at present and preserved in sediment sequences. One type of gypsum deposit forms a distinctive surface feature, which is here termed "gypsum ground". It consists of a thick (up to 80 cm) gypsum zone which rises from the surrounding smooth white playa surface and is overlain by a heaved brown crust. The gypsum zone, with an average gypsum content above 60%, consists of pure gypsum sublayers and interlayered clastic bands of sandy clay. The gypsum crystals are highly corroded, especially in the direction parallel to the c-axis and on the upper sides where illuviated clay has accumulated in corrosion hollows. Overgrowth parallel to the a- and b-axes is very common, forming highly discoidal habits. These secondary changes (corrosion and overgrowth) are well-developed in the vadose zone and absent from crystals below the long-term watertable (depth around 40 cm). These crystal characteristics indicate a rainwater leaching process. At Lake Amadeus, one of the largest playas (800 km 2) of central Australia, such gypsum ground occupies 16% of the total area. The gypsum ground is interpreted as an alteration of a pre-existing gypsum deposit which probably extended across the whole playa before breaking down, leaving a playa marginal terrace and several terrace islands within the gypsum ground. This pre-existing gypsum deposit, preserved in the residual islands, consists of pure, pale, sand-sized lenticular crystals. It is believed to have been deposited during an episode of high regional watertable, causing active groundwater seepage and more frequent surface brine in the playa. A later fall in watertable, probably resulting from climatic change

Simulating the structure of gypsum composites using pulverized basalt waste

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Buryanov Аleksandr

2017-01-01

Full Text Available This paper examines the possibility of simulating the structure of gypsum composite modified with basalt dust waste to make materials and products based on it. Structural simulating of the topological space in gypsum modified composite by optimizing its grain-size composition highly improves its physical and mechanical properties. Strength and density tests have confirmed the results of the simulation. The properties of modified gypsum materials are improved by obtaining of denser particle packing in the presence of hemihydrate of finely dispersed basalt and plasticizer particles in the system, and by engaging basalt waste in the structuring process of modified gypsum stone.

Basic Properties of Flue-Gas Desulfurization Gypsum

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Kovacs Ferenc

2003-03-01

Full Text Available Several hundred thousand of FGD gypsum is produced annually at the Matra Power Plant (Hungary as a byproduct of generating electricity and protecting the environment. Chemical and mechanical characteristics of this material were studied of the Department of Mining and Geotechnical Engineering, University of Miskolc (Hungary. The material in question was found dead gypsum which can be calcined easily to obtain a relatively high-strength (15-25 MPa and clean binding material. Furthermore, grain composites were made of it by adding fly ash, which the power plant can provide the expected producers with, thus decreasing the energy consumption of calcining and utilizing a small part of coal combustion wastes.

Use of FGD gypsum on a bermudagrass pasture in the Appalachian Plateau Region

Science.gov (United States)

Addition of industrial by-products from coal fired power plants (FGD gypsum and FGD gypsum + fly ash) are thought to increase plant production. Thus, a study was conducted to evaluate the effects of industrial by-products as a soil amendment on bermudagrass (Cynodon dactylon L.) yield. The study was...

High Levels of Antibiotic Resistance but No Antibiotic Production Detected Along a Gypsum Gradient in Great Onyx Cave, KY, USA

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Kathleen Lavoie

2017-09-01

Full Text Available A preliminary study of antibiotic production and antibiotic resistance was conducted in Great Onyx Cave in Mammoth Cave National Park, KY, to determine if gypsum (CaSO4∙2H2O affects these bacterial activities. The cave crosses through the width of Flint Ridge, and passages under the sandstone caprock are dry with different amounts of gypsum. The Great Kentucky Desert hypothesis posits that gypsum limits the distribution of invertebrates in the central areas of Great Onyx Cave. Twenty-four bacterial isolates were cultivated from swabs and soils. Using three methods (soil crumb, soil crumb with indicator bacteria, and the cross-streak method using isolated bacteria we did not detect any production of antibiotics. Antibiotic resistance was widespread, with all 24 isolates resistant to a minimum of two antibiotics of seven tested, with three isolates resistant to all. Antibiotic resistance was high and not correlated with depth into the cave or the amount of gypsum. The Great Kentucky Desert hypothesis of the negative effects of gypsum seems to have no impact on bacterial activity.

Soil composition and nutritional status of apple as affected by long-term application of gypsum

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Gilberto Nava

2012-02-01

Full Text Available Gypsum does not affect the soil negative charges and maintains sulfate in the soil solution, making it one of the cheapest products to increase Ca activity in soil solution, especially in the deeper soil layers. Higher Ca levels in the soil solution can increase the uptake of this nutrient by apple trees, reducing the risk of physiological disorders caused by Ca deficiency. This study assessed the effect of long-term gypsum application on some soil properties and on the chemical composition of leaves and fruits of an apple cultivar susceptible to fruit disorders associated with low Ca. The experiment was conducted in São Joaquim, in the South of Brazil, from 2001 to 2009. Gypsum rates of 0, 1.0, 2.0 and 3.0 t ha-1 were annually broadcast over the soil surface, without incorporation, in an apple orchard with cultivar ´Catarina´, planted in 1997. Gypsum application over eight consecutive years had no effect on soil exchangeable K and Al to a depth of 80 cm, but increased exchangeable Ca in the sampled layers (0-10, 10-20, 40-60 and 60-80 cm, while exchangeable Mg decreased only in the surface layer (0-20 cm. Gypsum did not affect the concentration of any nutrient in the fruits, including Ca. The same was verified in the leaves, except for Mg which decreased with increased gypsum rate. Despite increasing the availability of Ca in the soil profile to a depth of 80 cm, gypsum was not effective to increase the Ca content in leaves and fruits of an apple cultivar susceptible to Ca deficiency grown in an appropriately limed soil.

Evaluation of gypsum rates on greenhouse crop production

Science.gov (United States)

This study was to determine the potential of an added value distribution channel for gypsum waste by evaluating various greenhouse crops with captious pH and calcium needs. Three studies consisting of: Zonal geranium (Pelargonium x hortorum) and petunia (Petunia x hybrida); tomato (Solanum lycoper...

Evaluation of Synthetic Gypsum Recovered via Wet Flue-Gas Desulfurization from Electric Power Plants for Use in Foundries

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R. Biernacki

2012-09-01

Full Text Available This article investigates possible use of waste gypsum (synthetic, recovered via flue-gas desulfurization from coal-fired electric powerplants, in foundries. Energy sector, which in Eastern Europe is mostly composed from coal-fired electric power plants, is one of the largestproducers of sulfur dioxide (SO2.In order to protect the environment and reduce the amount of pollution flue-gas desulfurization (FGD is used to remove SO2 fromexhaust flue gases of fossil-fuel power plants. As a result of this process gypsum waste is produced that can be used in practicalapplications.Strength and permeability tests have been made and also in-depth analysis of energy consumption of production process to investigateways of preparing the synthetic gypsum for casting moulds application. This paper also assesses the chemical composition, strength andpermeability of moulds made with synthetic gypsum, in comparison with moulds made with traditional GoldStar XL gypsum and withceramic molds. Moreover examination of structure of synthetic gypsum, the investigations on derivatograph and calculations of energyconsumption during production process of synthetic gypsum in wet flue-gas desulfurization were made.After analysis of gathered data it’s possible to conclude that synthetic gypsum can be used as a material for casting mould. There is nosignificant decrease in key properties, and on the other hand there is many additional benefits including low energy consumption,decreased cost, and decreased environmental impact.

Influence of gypsum amendment on methane emission from paddy rice soil affected by saline irrigation water

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Ei Ei eTheint

2016-01-01

Full Text Available To investigate the influence of gypsum application on methane (CH4 emission from paddy rice soil affected by saline irrigation water, two pot experiments with the rice cultivation were conducted. In pot experiment (I, salinity levels 30 mMNaCl (S30 and 90 mMNaCl (S90, that showed maximum and minimum CH4 production in an incubation experiment, respectively, were selected and studied without and with application of 1 Mg gypsum ha-1(G1. In pot experiment (II, CH4 emission was investigated under different rates of gypsum application: 1 (G1, 2.5 (G2.5 and 5 (G5 Mg gypsum ha-1 under a non-saline and saline condition of 25 mMNaCl (S25. In experiment (I, the smallest CH4 emission was observed in S90. Methane emission in S30 was not significantly different with the non-saline control. The addition of gypsum showed significant lower CH4 emission in saline and non-saline treatments compared with non-saline control. In experiment (II, the CH4 emissions in the saline treatments were not significantly different to the non-saline treatments except S25-G5. However, our work has shown that gypsum can lower CH4 emissions under saline and non-saline conditions. Thus, gypsum can be used as a CH4 mitigation option in non-saline as well as in saline conditions.

Impact of welan gum on tricalcium aluminate–gypsum hydration

International Nuclear Information System (INIS)

Ma Lei; Zhao Qinglin; Yao Chukang; Zhou Mingkai

2012-01-01

The retarding effect of welan gum on tricalcium aluminate–gypsum hydration, as a partial system of ordinary Portland cement (OPC) hydration, was investigated with several methods. The tricalcium aluminate–gypsum hydration behavior in the presence or absence of welan gum was researched by field emission gun scanning electron microscopy, X-ray diffraction and zeta potential analysis. Meanwhile, we studied the surface electrochemical properties and adsorption characteristics of welan gum by utilizing a zeta potential analyzer and UV–VIS absorption spectrophotometer. By adding welan gum, the morphology change of ettringite and retardation of hydration stages in tricalcium aluminate–gypsum system was observed. Moreover, we detected the adsorption behavior and zeta potential inversion of tricalcium aluminate and ettringite, as well as a rapid decrease in the zeta potential of tricalcium aluminate–gypsum system. The reduction on nucleation rate of ettringite and hydration activity of C 3 A was also demonstrated. Thus, through the adsorption effect, welan gum induces a retarding behavior in tricalcium aluminate–gypsum hydration. Highlights: ► Adsorption characteristics of welan gum on C 3 A and ettringite have been studied. ► C 3 A–gypsum hydration behavior and the hydration products are examined in L/S = 3. ► Welan gum retards the process of C 3 A–gypsum hydration. ► The addition of welan gum changes the nucleation growth of ettringite.

MARKETING OF BYPRODUCT GYPSUM FROM FLUE GAS DESULFURIZATION

Science.gov (United States)

The report gives results of an evaluation of the 1985 marketing potential of byproduct gypsum from utility flue gas desulfurization (FGD), for the area east of the Rocky Mountains, using the calculated gypsum production rates of 14 selected power plants. The 114 cement plants and...

Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder

International Nuclear Information System (INIS)

Zhong Shiyun; Ni Kun; Li Jinmei

2012-01-01

Highlights: ► The mortar with uncalcined FGD gypsum has suitable workability. ► The strength of mortar with uncalcined FGD gypsum is higher than that of mortar without uncalcined FGD gypsum. ► The dry shrinkage of mortar with uncalcined FGD gypsum is lower than that of mortar without uncalcined FGD gypsum. ► The leaching of sulfate ion of mortar is studied. - Abstract: A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C–S–H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563–938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO 4 2- from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO 4 2- releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO 4 2- from the mortar with 20% FGD gypsum is 9200 mg·m −2 , which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum.

GYPSUM DEPOSITS IN THE REPUBLIC OF CROATIA

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Anto Gabrić

2002-12-01

Full Text Available The occurences and deposits of gypsum can be found in big karst poljes (Sinjsko, Vrličko, Petrovo, Kosovo and Kninsko as well as in tectonnically predestined river valleys of Zrmanja, Butišnica and Una. There also appear spatially localized occurences on the island of Vis and in the vicinity of Samobor. Evaporites (gypsum and anhydrite with adjoining overlying clastic rocks (red sandstones, siltites and pelites, carbonate rocks (dolomites and limestones and porous carbonate breccias (Rauhwackes were deposited during the period of Upper Permian. The recent position of the Upper Permian beds is a result of complex tectonic, particularly neotectonic, movements and diapiric displacements. Evaporites were deposited in marginal areas of the epicontinental marine basin, in a period of favourable conditions for the sabkha and playa sedimentation due to the continuous shoreline progradation. The Upper Permian age of these sediments in Dalmatio is proved by the characteristic mineral paragenesis and palinological determinations in elastics rocks, as well as by isotope analyses of sulphure in gypsum. Gypsum is a significant ore mineral resource in building, cement production, as well as in a number of tehnological processes used in chemical industry and elsewhere. According to the recent investigations gypsum is predestined to serve as an ore mineral resource of significant perspectives (the paper is published in Croatian.

Gypsum as a bedding source for broiler chickens

Science.gov (United States)

Three trials examined the feasibility of flue gas desulfurization gypsum as a bedding material for raising broilers. Gypsum was used alone, under or on top of pine shavings and pine bark. Test materials were placed as bedding in pens to simulate commercial broiler production through three growout cy...

Risk minimisation of FGD gypsum leachates by incorporation of aluminium sulphate

Energy Technology Data Exchange (ETDEWEB)

Alvarez-Ayuso, E. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Department of Environmental Geochemistry, IRNASA, CSIC, Apto. 257, 37071 Salamanca (Spain)], E-mail: ealvarez@ija.csic.es; Querol, X. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Ballesteros, J.C.; Gimenez, A. [Endesa Generacion, S.A., C/ Ribera de Loira, 60, 28042 Madrid (Spain)

2008-11-15

The incorporation of aluminium sulphate to (flue gas desulphurisation) FGD gypsum before its disposal was investigated as a way to minimise the risk supposed by the high fluoride content of its leachates. Using a bath method the kinetic and equilibrium processes of fluoride removal by aluminium sulphate were studied at fluoride/aluminium molar concentration (F/Al) ratios in the range 1.75 10{sup -2}-1.75 under the pH conditions (about 6.5) of FGD gypsum leachates. It was found that fluoride removal was a very fast process at any of the (F/Al) ratios subject of study, with equilibrium attained within the first 15 min of interaction. High decreases in solution fluoride concentrations (50-80%) were found at the equilibrium state. The use of aluminium sulphate in the stabilization of FGD gypsum proved to greatly decrease its fluoride leachable content (in the range 20-90% for aluminium sulphate doses of 0.1-5%, as determined by the European standard EN 12457-4). Such fluoride leaching minimisation assures the characterization of this by-product as a waste acceptable at landfills for non-hazardous wastes according to the Council Decision 2003/33/EC on waste disposal. Furthermore, as derived from column leaching studies, the proposed stabilization system showed to be highly effective in simulated conditions of disposal, displaying fluoride leaching reduction values about 55 and 80% for aluminium sulphate added amounts of 1 and 2%, respectively.

Tunisian gypsums: Characteristics and use in cement

Science.gov (United States)

Mahmoudi, Salah; Bennour, Ali; Chalwati, Youssef; Souidi, Khouloud; Thabet, Manel; Srasra, Ezzedine; Zargouni, Fouad

2016-09-01

Gypsum materials of hundred meters thickness and interbedded with marine claystones and limestones from different paleogeographic sectors in the Tunisian territory are studied to assess their suitability for cement production. For this reason, thirty representative samples are analysed by chemical, physical and geotechnical tests. The obtained results for the studied gypsum materials are compared to Tunisian and European norms and with the local cements, currently marketed and which obey international norms. Indeed, for all samples hydraulic modulus HM, silica modulus SM and alumina modulus AM vary from (2.37-2.44), (2.48-2.68) and (1.45-2.5), respectively; whereas the required values for these modulus are (1.5-2.5), (2-3) and (1.5-2.5). The same behavior is observed for mineralogical analyses of C3S, C2S, C3A and C4AF and compressive strength at different ages. Briefly, Tunisia contains important reserves of gypsum scattered and spread over the Tunisian territory and can be used for cement production.

Gypsum accumulation on carbonate stone

Science.gov (United States)

McGee, E.S.; Mossotti, V.G.

1992-01-01

The accumulation of gypsum on carbonate stone has been investigated through exposure of fresh samples of limestone and marble at monitored sites, through examination of alteration crusts from old buildings and through laboratory experiments. Several factors contribute to gypsum accumulation on carbonate stone. Marble or limestone that is sheltered from direct washing by rain in an urban environment with elevated pollution levels is likely to accumulate a gypsum crust. Crust development may be enhanced if the stone is porous or has an irregular surface area. Gypsum crusts are a surficial alteration feature; gypsum crystals form at the pore opening-air interface, where evaporation is greatest.

Flue gas desulfurization gypsum: Its effectiveness as an alternative bedding material for broiler production

Science.gov (United States)

Flue gas desulfurization gypsum (FGDG) may be a viable low-cost alternative bedding material for broiler production. In order to evaluate FGD gypsum’s viability, three consecutive trials were conducted to determine its influence on live performance (body weight, feed consumption, feed efficiency, an...

Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder.

Science.gov (United States)

Zhong, Shiyun; Ni, Kun; Li, Jinmei

2012-07-01

A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO(4)(2-) from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO(4)(2-) releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO(4)(2-) from the mortar with 20% FGD gypsum is 9200 mg·m(-2), which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum. Copyright © 2012 Elsevier Ltd. All rights reserved.

NOx photocatalytic degradation on gypsum plates modified by TiO2-N,C photocatalysts

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Janus Magdalena

2015-09-01

Full Text Available In presented studies the photocatalytic decomposition of NOx on gypsum plates modified by TiO2-N,Cphotocatalysts were presented. The gypsum plates were obtained by addition of 10 or 20 wt.% of different types of titanium dioxide, such as: pure TiO2 and carbon and nitrogen co-modified TiO2 (TiO2-N,C to gypsum. TiO2-N,C photocatalysts were obtained by heating up the starting TiO2 (Grupa Azoty Zakłady Chemiczne Police S.A in the atmosphere of ammonia and carbon at the temperature: 100, 300 i 600ºC. Photocatalyst were characterized by FTIR/DRS, UVVis/DR, BET and XRD methods. Moreover the compressive strength tests of modified gypsum were also done. Photocatalytic activity of gypsum plates was done during NOx decomposition. The highest photocatalytic activity has gypsum with 20 wt.% addition of TiO2-N,C obtained at 300ºC.

Potential Agricultural Uses of Flue Gas Desulfurization Gypsum in the Northern Great Plains

Energy Technology Data Exchange (ETDEWEB)

DeSutter, T.M.; Cihacek, L.J. [North Dakota State University, Fargo, ND (United States). Department of Soil Science

2009-07-15

Flue gas desulfurization gypsum (FGDG) is a byproduct from the combustion of coal for electrical energy production. Currently, FGDG is being produced by 15 electrical generating stations in Alabama, Florida, Indiana, Iowa, Kentucky, Ohio, North Carolina, South Carolina, Tennessee, Texas, and Wisconsin. Much of this byproduct is used in the manufacturing of wallboard. The National Network for Use of FGDG in Agriculture was initiated to explore alternative uses of this byproduct. In the northern Great Plains (North Dakota, South Dakota, and Montana), FGDG has the potential to be used as a Ca or S fertilizer, as an acid soil ameliorant, and for reclaiming or mitigating sodium-affected soils. Greater than 1.4 million Mg of FGDG could initially be used in these states for these purposes. Flue gas desulfurization gypsum can be an agriculturally important resource for helping to increase the usefulness of problem soils and to increase crop and rangeland production. Conducting beneficial use audits would increase the public awareness of this product and help identify to coal combustion electrical generating stations the agriculturally beneficial outlets for this byproduct.

Extension of the possibilities for disposal of the flue gas desulfurization (FGD) gypsum by the development of a process for the production of FGD gypsum. Final report. Erweiterung der Entsorgungsmoeglichkeiten von REA-Gips durch Entwicklung eines Verfahrens zur Herstellung von REA-Anhydrit aus REA-Gips. Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Limmer, B.; Hueller, R.

1990-01-01

In the course of this research project a completly new transformation of FGD-gypsum into FGD-anhydrite has been studied. The reaction is catalysed by small quantities of sulphuric acid resulting in a FGD-anhydrite without combined water and with an orthorhombic crystal lattice. The course of reaction was thoroughly investigated by laboratory test and hypothesis have been put forward. The process engineering has been developed from laboratory to pilot plant scale. The FGD-anhydrite is technologically a novel product. The idea was to create it for cement industry as well as to put it on the filler market as a raw product. In principle, FGD-anhdrite will be suitable for the use in the cement industry due to its characteristics. However, it is not interesting for this market in this moment. With respect to the filler industry, this application will enable a further-reaching usability of the FGD-gypsum than the traditional scope of the gypsum industry. First experiments show that the specific properties of processed FGD-anhydrite may qualify it as a high-grade filler. (orig.) With 18 refs., 21 tabs., 41 figs.

Synthesis of partial stabilized cement-gypsum as new dental retrograde filling material

Energy Technology Data Exchange (ETDEWEB)

Sadhasivam, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China); Chen, Jung-Chih [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan,Taiwan (China); Savitha, S. [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Hsu, Ming-Xiang; Hsu, Chung-King [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei, Taiwan (China); Lin, Chun-Pin [School of Dentistry and Graduate Institute of Clinical Dentistry, College of Medicine, National Taiwan University and National Taiwan University Hospital, Taipei, Taiwan (China); Lin, Feng-Huei, E-mail: double@ntu.edu.tw [Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan (China); Division of Medical Engineering Research, National Health Research Institute, Zhunan, Miaoli County, Taiwan (China)

2012-10-01

The study describes the sol-gel synthesis of a new dental retrograde filling material partial stabilized cement (PSC)-gypsum by adding different weight percentage of gypsum (25% PSC + 75% gypsum, 50% PSC + 50% gypsum and 75% PSC + 25% gypsum) to the PSC. The crystalline phase and hydration products of PSC-gypsum were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The handling properties such as setting time, viscosity, tensile strength, porosity and pH, were also studied. The XRD and microstructure analysis demonstrated the formation of hydroxyapatite and removal of calcium dihydrate during its immersion in simulated body fluid (SBF) on day 10 for 75% PSC + 25% gypsum. The developed PSC-gypsum not only improved the setting time but also greatly reduced the viscosity, which is very essential for endodontic surgery. The cytotoxic and cell proliferation studies indicated that the synthesized material is highly biocompatible. The increased alkaline pH of the PSC-gypsum also had a remarkable antibacterial activity. - Highlights: Black-Right-Pointing-Pointer A new dental retrograde filling material PSC-gypsum was developed. Black-Right-Pointing-Pointer PSC-gypsum cement has shown excellent initial and final setting time as 15-35 min. Black-Right-Pointing-Pointer It not only improved the setting time but also retain the viscosity, 2 Pa{center_dot}s. Black-Right-Pointing-Pointer High alkaline pH of the cement had a remarkable antibacterial activity. Black-Right-Pointing-Pointer Cytotoxicity studies revealed that the synthesized material is highly biocompatible.

The Gypsum: White gold of Rajasthan, introduction, uses and future prospective

Science.gov (United States)

Sharma, Gayatri

2013-06-01

Rajasthan is mineral based state and Bikaner and its surrounding district have been gifted with Gypsum. Mt of Gypsum is available in these districts. Gypsum has multiple uses including basic raw material for POP industry, addition in cement and a natural fertilizer. This mineral has changes the economic scenario in the remote areas of Bikaner, Nagaur, Hanumangarh, Sanchore, Shriganganagar etc. Gypsum and selenite are mined about 3.0 million tons per year. There is huge demand from cement industry as Gypsum is added for improving setting time of cement. Gypsum is a natural fertilizer for alkaline land and it role is vital in state like India where alkaline land is major role. Its high use as fertilizer has potential to change millions of poor farmer families and improving in crop production. Cement Industry has started importing Gypsum from Thailand, Bankong, Pakistan, Iran etc. The mining of gypsum of purity of 70% CaSO4.2H2O is cooperative effort between the land owners and Rajasthan State Mines and Minerals Limited. Gypsum fulfills the demand of POP and Cement industry in Rajasthan and powder gypsum used in agriculture for recon dining of alkaline soil. This paper deals with multiple uses, availability, and future prospective of Gypsum, a white gold of Rajasthan.

Hydrogeology of Gypsum formations

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Klimchouk A.

1996-01-01

Full Text Available Detailed explanation of hydrogeological characteristics of gypsum aquifers is given in various situations: deep-seated karst-confined conditions, subjacent, entrenched and denuded karst types-semi-confined, phreatic and vadose conditions. The hydrogeological evolution of barren exposed gypsum karst and flow velocities in gypsum karst aquifers is also discussed.

Effect of shelf life on compressive strength of type iv gypsum

Science.gov (United States)

Kusumastuti, K. S.; Irawan, B.; Damiyanti, M.

2017-08-01

Type IV gypsum, as a dental material for an indirect restoration’s working model, should have strength and abrasive-resistant properties. These properties depend on the product’s shelf life and its proper storage, which sometimes are easily missed by sellers. The aim of this research was to observe the effect of shelf life on the compressive strength of type IV gypsum with different production dates. Twenty cylindrical specimens were separated into two groups with different production dates and tested with a universal testing with the crosshead speed of 1 mm per minute and a load of 2,500 kgf. The data were analyzed with independent t-tests. There was a significant difference (p<0.05) in the compressive strength between the two groups with an increase in compressive strength seen in the gypsum that was stored longer.

Investigation and dating of gypsum crystals from Sivrihisar region in Eskisehir by ESR and TL techniques

International Nuclear Information System (INIS)

2011-01-01

Gypsum crystals taken from Sivrihisar-Eskisehir district were investigated and dated by Electron Spin Resonance (ESR) and Thermoluminescence (TL) techniques. The natural ESR spectra of gypsum samples had also the signals of Mn 2 + in addition to the signal at g=2.009. It was observed that the intensity of ESR signal at g=2.009 increased with gamma irradiation dose. This ESR signal (g=2.009) was used as a dating signal in dating of gypsum samples. The only one TL peak at about 278 degree Celsius was observed in TL glow curves of nonirradiated gypsum sample. In the case of irradiated sample, TL peak at 157 degree Celsius was observed in addition of TL peak at 278 degree Celsius. Gypsum samples were irradiated with a 6 0Co gamma source. The ESR spectra and TL glow curve of gypsum samples were recorded by X-band ESR spectrometer and Risφ TL/OSL reader, respectively. For samples, ESR/TL dose-response curves was constructed. Dose-response curves were fitted with an exponential saturation function. Based on this model, accumulated dose (AD) values for dating are determined. 2 38U, 2 32Th and 4 0K analysis was carried out for gypsum crystals and dolomite which enveloped these gypsum crystals. The internal dose rate was calculated from 2 38U, 2 32Th and 4 0K analysis results of gypsum sample. The external dose rate was calculated by using 2 38U, 2 32Th and 4 0K analysis results of dolomite and cosmic dose rate. Internal and external gamma dose-rate was used for dating calculations. Because of successive recrystallization of gypsum sample after formation, calculated age values of gypsum is smaller than expected formation age.

Incorporation of gypsum waste in ceramic block production: Proposal for a minimal battery of tests to evaluate technical and environmental viability of this recycling process.

Science.gov (United States)

Godinho-Castro, Alcione P; Testolin, Renan C; Janke, Leandro; Corrêa, Albertina X R; Radetski, Claudemir M

2012-01-01

Civil engineering-related construction and demolition debris is an important source of waste disposed of in municipal solid waste landfills. After clay materials, gypsum waste is the second largest contributor to the residential construction waste stream. As demand for sustainable building practices grows, interest in recovering gypsum waste from construction and demolition debris is increasing, but there is a lack of standardized tests to evaluate the technical and environmental viability of this solid waste recycling process. By recycling gypsum waste, natural deposits of gypsum might be conserved and high amounts of the waste by-product could be reused in the civil construction industry. In this context, this paper investigates a physical property (i.e., resistance to axial compression), the chemical composition and the ecotoxicological potential of ceramic blocks constructed with different proportions of clay, cement and gypsum waste, and assesses the feasibility of using a minimal battery of tests to evaluate the viability of this recycling process. Consideration of the results for the resistance to axial compression tests together with production costs revealed that the best formulation was 35% of plastic clay, 35% of non-plastic clay, 10% of Portland cement and 20% of gypsum waste, which showed a mean resistance of 4.64MPa. Energy dispersive X-ray spectrometry showed calcium and sulfur to be the main elements, while quartz, gypsum, ettringite and nacrite were the main crystalline compounds found in this formulation. Ecotoxicity tests showed that leachate from this formulation is weakly toxic toward daphnids and bacteria (EC(20%)=69.0 and 75.0, respectively), while for algae and fish the leachate samples were not toxic at the EC(50%) level. Overall, these results show that the addition of 20% of gypsum waste to the ceramic blocks could provide a viable substitute for clay in the ceramics industry and the tests applied in this study proved to be a useful tool

Flue gas desulfurization gypsum and fly ash

International Nuclear Information System (INIS)

1992-05-01

The Cumberland Fossil Plant (CUF) is located in Stewart County, Tennessee, and began commercial operation in 1972. This is the Tennessee Valley Authority's newest fossil (coal-burning) steam electric generating plant. Under current operating conditions, the plant burns approximately seven million tons of coal annually. By-products from the combustion of coal are fly ash, approximately 428,000 tons annually, and bottom ash, approximately 115,000 tons annually. Based on historical load and projected ash production rates, a study was initially undertaken to identify feasible alternatives for marketing, utilization and disposal of ash by-products. The preferred alternative to ensure that facilities are planned for all by-products which will potentially be generated at CUF is to plan facilities to handle wet FGD gypsum and dry fly ash. A number of different sites were evaluated for their suitability for development as FGD gypsum and ash storage facilities. LAW Engineering was contracted to conduct onsite explorations of sites to develop information on the general mature of subsurface soil, rock and groundwater conditions in the site areas. Surveys were also conducted on each site to assess the presence of endangered and threatened species, wetlands and floodplains, archaeological and cultural resources, prime farmland and other site characteristics which must be considered from an environmental perspective

A Scanning Transmission X-ray Microscopy Study of Cubic and Orthorhombic C3A and Their Hydration Products in the Presence of Gypsum

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Vanessa Rheinheimer

2016-08-01

Full Text Available This paper shows the microstructural differences and phase characterization of pure phases and hydrated products of the cubic and orthorhombic (Na-doped polymorphs of tricalcium aluminate (C3A, which are commonly found in traditional Portland cements. Pure, anhydrous samples were characterized using scanning transmission X-ray microscopy (STXM, X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD and demonstrated differences in the chemical and mineralogical composition as well as the morphology on a micro/nano-scale. C3A/gypsum blends with mass ratios of 0.2 and 1.9 were hydrated using a water/C3A ratio of 1.2, and the products obtained after three days were assessed using STXM. The hydration process and subsequent formation of calcium sulfate in the C3A/gypsum systems were identified through the changes in the LIII edge fine structure for Calcium. The results also show greater Ca LII binding energies between hydrated samples with different gypsum contents. Conversely, the hydrated samples from the cubic and orthorhombic C3A at the same amount of gypsum exhibited strong morphological differences but similar chemical environments.

IMPACT OF NANOMODIFIERS ON MECHANICAL AND PHYSICAL PROPERTIES OF GYPSUM BINDERS

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DEREVIANKO V. N.

2017-02-01

Full Text Available Summary. Problem statement. In the next 10 years, more than 90% of materials will be replaced with new materials – nanocomposites [1]. The nanocomponents application will allow manufacture of high-strength materials with reduced production cost and will ensure demand for products [2]. Researches aimed to determination of carbon nanotube type nanomodifier concentration impact on the physical and mechanical properties of gypsum binders are important today and must result in creation of competitive strong nano-materials. Purpose. Research of carbon nanotube (CNT type nanomodifier concentration impact on the physical and mechanical properties of gypsum binders. Conclusion. Sample microstructure analysis revealed that the non-modified gypsum sample structure is dominated by prismatic and lamellar crystals randomly distributed throughout the matrix volume. In this case, loose structure with increased porosity is formed, which results in sample mechanical strength reduction. In the CNT-modified gypsum matrix, well-ordered and homogeneous structure is formed with larger needle-shaped crystals, which results in the phase-contacting area increase, porosity reduction and thus the physical and mechanical characteristics improvement. It is experimentally proved that at the identical nano-modifier content in the gypsum matrix (0.035 %, maximum compression strength gain is achieved with the use of CNT and makes 28- 30%. At the use of initial carbon nanotubes, increase in strength at the same nano-modifier content makes 13-15%. The Ca2+ ions interaction with the graphene-like carbon surface was investigated by the DFT method. Capability is demonstrated of the covalent calcium bonding with the hexagonal carbon surface cell as a result of overlap of Ca2+ valence 3p orbitals and carbon 2р orbitals.

Gypsum crystals observed in experimental and natural sea ice

Science.gov (United States)

Geilfus, N.-X.; Galley, R. J.; Cooper, M.; Halden, N.; Hare, A.; Wang, F.; Søgaard, D. H.; Rysgaard, S.

2013-12-01

gypsum has been predicted to precipitate in sea ice, it has never been observed. Here we provide the first report on gypsum precipitation in both experimental and natural sea ice. Crystals were identified by X-ray diffraction analysis. Based on their apparent distinguishing characteristics, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the "Gitterman pathway" where gypsum is predicted to precipitate. The occurrence of authigenic gypsum in sea ice during its formation represents a new observation of precipitate formation and potential marine deposition in polar seas.

Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel

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Mohammad Misbah Khunur

2012-06-01

Full Text Available This paper report the synthesis and characterization of fluorite single crystal prepared from gypsum waste of phosphoric acid production in silica gel. Instead of its high calcium, gypsum was used to recycle the waste which was massively produces in the phosphoric acid production. The gypsum waste, the raw material of CaCl2 supernatant, was dissolved in concentrated HCl and then precipitated as calcium oxalate (CaC2O4 by addition of ammonium oxalate. The CaCl2 was obtained by dissolving the CaC2O4 with HCl 3M. The crystals were grown at room temperature in silica gel and characterized by AAS, FTIR and powder XRD. The optimum crystal growth condition, which is pH of gel, CaCl2 concentration and growth time, were investigated. The result shows that at optimum condition of pH 5.80, CaCl2 concentrations of 1.2 M, and growth time of 144 hours, colorless crystals with the longest size of 3 mm, were obtained (72.57%. Characterization of the synthesized crystal by AAS indicates that the obtained crystal has high purity. Meanwhile, analysis by FTIR spectra shows a Ca–F peak at 775 cm-1, and powder-XRD analysis confirms that the obtained crystal was fluorite (CaF2. © 2012 BCREC UNDIP. All rights reservedReceived: 11st April 2012; Revised: 4th June 2012; Accepted: 13rd June 2012[How to Cite: M.M. Khunur, A. Risdianto, S. Mutrofin, Y.P. Prananto. (2012. Synthesis of Fluorite (CaF2 Crystal from Gypsum Waste of Phosphoric Acid Factory in Silica Gel. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 71-77.  doi:10.9767/bcrec.7.1.3171.71-77 ][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.3171.71-77 ] | View in 

Unravelling the mechanisms for plant survival on gypsum soils: an analysis of the chemical composition of gypsum plants from Turkey.

Science.gov (United States)

Bolukbasi, A; Kurt, L; Palacio, S

2016-03-01

Depending on their specificity to gypsum, plants can be classified as gypsophiles (gypsum exclusive) and gypsovags (non-exclusive). The former may further be segregated into wide and narrow gypsophiles, depending on the breadth of their distribution area. Narrow gypsum endemics have a putative similar chemical composition to plants non-exclusive to gypsum (i.e. gypsovags), which may indicate their similar ecological strategy as stress-tolerant plant refugees on gypsum. However, this hypothesis awaits testing in different regions of the world. We compared the chemical composition of four narrow gypsum endemics, one widely distributed gypsophile and six gypsovags from Turkey. Further, we explored the plasticity in chemical composition of Turkish gypsovags growing on high- and low-gypsum content soils. Differences were explored with multivariate analyses (RDA) and mixed models (REML). Narrow gypsum endemics segregated from gypsovags in their chemical composition according to RDAs (mainly due to higher K and ash content in the former). Nevertheless, differences were small and disappeared when different nutrients were analysed individually. All the gypsovags studied accumulated more S and ash when growing on high-gypsum than on low-gypsum soils. Similar to narrow gypsum endemics from other regions of the world, most local gypsum endemics from Turkey show a similar chemical composition to gypsovags. This may indicate a shared ecological strategy as stress-tolerant plants not specifically adapted to gypsum. Nevertheless, the narrow gypsum endemic Gypsophila parva showed a chemical composition typical of gypsum specialists, indicating that various strategies are feasible within narrowly distributed gypsophiles. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Physicochemical Properties and Cellular Responses of Strontium-Doped Gypsum Biomaterials

OpenAIRE

Pouria, Amir; Bandegani, Hadis; Pourbaghi-Masouleh, Milad; Hesaraki, Saeed; Alizadeh, Masoud

2012-01-01

This paper describes some physical, structural, and biological properties of gypsum bioceramics doped with various amounts of strontium ions (0.19–2.23 wt%) and compares these properties with those of a pure gypsum as control. Strontium-doped gypsum (gypsum:Sr) was obtained by mixing calcium sulfate hemihydrate powder and solutions of strontium nitrate followed by washing the specimens with distilled water to remove residual salts. Gypsum was the only phase found in the composition of both pu...

Composting of waste paint sludge containing melamine resin as affected by nutrients and gypsum addition and microbial inoculation

International Nuclear Information System (INIS)

Tian Yongqiang; Chen Liming; Gao Lihong; Michel, Frederick C.; Wan Caixia; Li Yebo; Dick, Warren A.

2012-01-01

Melamine formaldehyde resins have hard and durable properties and are found in many products, including automobile paints. These resins contain high concentrations of nitrogen and, if properly composted, can yield valuable products. We evaluated the effects of starter compost, nutrients, gypsum and microbial inoculation on composting of paint sludge containing melamine resin. A bench-scale composting experiment was conducted at 55 °C for 91 days and then at 30 °C for an additional 56 days. After 91 days, the composts were inoculated with a mixed population of melamine-degrading microorganisms. Melamine resin degradation after the entire 147 days of composting varied between 73 and 95% for the treatments with inoculation of microorganisms compared to 55–74% for the treatments without inoculation. Degradation was also enhanced by nutrients and gypsum additions. Our results infer that large scale composting of melamine resins in paint sludge is possible. - Highlights: ► Melamine resin in waste paint sludges could be efficiently composted at bench scale. ► Melamine resin degradation after 147 days of composting was 73–95% complete. ► Nutrients, gypsum and melamine-degrading microorganisms increased composting rate. ► Melamine degradation products first increased and then decreased in the compost. ► Final compost was enriched in nitrogen and other essential plant nutrients. - Melamine resin in waste paint sludges was efficiently composted at bench scale, with finished composts having low levels of heavy metals and enriched in plant nutrients.

Gypsum amendment to soil can reduce selenium uptake by alfalfa grown in the presence of coal fly ash

International Nuclear Information System (INIS)

Arthur, M.A.; Rubin, G.; Woodbury, P.B.; Weinstein, L.H.

1993-01-01

Experiments in the field and greenhouse were conducted in the presence of coal fly ash to determine whether gypsum can reduce Se concentration in alfalfa (Medicago sativa L.). In the field experiment, conducted at a coal fly ash landfill, 11.2 t ha -1 gypsum was applied to soil as a top dressing to test the effect of gypsum in reducing selenium (Se) concentration in aboveground plant tissue. There were four treatment combinations of gypsum over a two year period, 1990, and 1991: (0, 0), (0, 11.2) (11.2, 0) and (11.2, 11.2). In 1991, the Se concentration was lower in alfalfa grown with gypsum, regardless of whether the gypsum was applied in both years or in only one year, indicating that the effect of gypsum application in the first year persisted into the second year. Since there was no increase in aboveground biomass with added gypsum, differences in Se concentration reflect a competitive interaction between S and Se. In the greenhouse experiment, 12 soil treatments were tested: three levels of fly ash (0, 10 and 20%) in combination with each of four levels of gypsum (0, 2.5, 5 and 7.5%). The Se concentration in alfalfa grown in 10% fly ash declined linearly with increasing gypsum dose, resulting in a reduction in Se concentration of 0.04 ± 0.02 μg g -1 for each 1% gypsum added for the first harvest and 0.06 ± 0.03 μg g -1 for each 1% gypsum added in the second harvest. Based on these results, gypsum may prove useful as a management tool to reduce the uptake of Se by plants growing on coal fly ash landfills

STRUCTURE AND PROPERTIES OF COMPOSITE MATERIAL BASED ON GYPSUM BINDER AND CARBON NANOTUBES

Directory of Open Access Journals (Sweden)

CHUMAK Anastasia Gennadievna

2013-04-01

Full Text Available The aim of this work is to carry out a number of studies in the area of nanomodi­fication of gypsum binder matrix and to investigate the influence of multilayer carbon nanotubes on the structure, physical and mechanical properties of obtained compos­ites. The study of the gypsum binders structure formation mechanisms with the use of nanoadditives makes it possible to control the production processes of gypsum materi­als and articles with the given set of properties. The main tasks of the binder nanomodification are: even distribution of carbon nanostructures over the whole volume of material and provision of stability for the nanodimensional modifier during production process of the construction composite.

Effect of Time on Gypsum-Impression Material Compatibility

Science.gov (United States)

Won, John Boram

The purpose of this study was to evaluate the compatibility of dental gypsum with three recently introduced irreversible hydrocolloid (alginate) alternatives. The test materials were Alginot® (Kerr™), Position Penta Quick® (3M ESPE™) and Silgimix ® (Sultan Dental™). The irreversible hydrocolloid impression material, Jeltrate Plus antimicrobial® (Dentsply Caulk™) served as the control. Materials and Methods: Testing of materials was conducted in accordance with ANSI/ADA Specification No. 18 for Alginate Impression Materials. Statistical Analysis: The 3-Way ANOVA test was used to analyze measurements between different time points at a significance level of (p Outcome: It was found that there was greater compatibility between gypsum and the alternative materials over time than the traditional irreversible hydrocolloid material that was tested. A statistically significant amount of surface change/incompatibility was found over time with the combination of the dental gypsum products and the control impression material (Jeltrate Plus antimicrobial®).

Surface Coating of Gypsum-Based Molds for Maxillofacial Prosthetic Silicone Elastomeric Material: The Surface Topography.

Science.gov (United States)

Khalaf, Salah; Ariffin, Zaihan; Husein, Adam; Reza, Fazal

2015-07-01

This study aimed to compare the surface roughness of maxillofacial silicone elastomers fabricated in noncoated and coated gypsum materials. This study was also conducted to characterize the silicone elastomer specimens after surfaces were modified. A gypsum mold was coated with clear acrylic spray. The coated mold was then used to produce modified silicone experimental specimens (n = 35). The surface roughness of the modified silicone elastomers was compared with that of the control specimens, which were prepared by conventional flasking methods (n = 35). An atomic force microscope (AFM) was used for surface roughness measurement of silicone elastomer (unmodified and modified), and a scanning electron microscope (SEM) was used to evaluate the topographic conditions of coated and noncoated gypsum and silicone elastomer specimens (unmodified and modified) groups. After the gypsum molds were characterized, the fabricated silicone elastomers molded on noncoated and coated gypsum materials were evaluated further. Energy-dispersive X-ray spectroscopy (EDX) analysis of gypsum materials (noncoated and coated) and silicone elastomer specimens (unmodified and modified) was performed to evaluate the elemental changes after coating was conducted. Independent t test was used to analyze the differences in the surface roughness of unmodified and modified silicone at a significance level of p SEM analysis results showed evident differences in surface smoothness. EDX data further revealed the presence of the desired chemical components on the surface layer of unmodified and modified silicone elastomers. Silicone elastomers with lower surface roughness of maxillofacial prostheses can be obtained simply by coating a gypsum mold. © 2014 by the American College of Prosthodontists.

Manufacturing of calcium phosphate scaffolds by pseudomorphic transformation of gypsum

Energy Technology Data Exchange (ETDEWEB)

Araujo Batista, H. de.; Batista Cardoso, M.; Sales Vasconcelos, A.; Vinicius Lia Fook, M.; Rodriguez Barbero, M. A.; Garcia Carrodeguas, R.

2016-08-01

Carbonated hydroxyapatite (CHAp) and β-tricalcium phosphate (β-TCP) have been employed for decades as constituents of scaffolds for bone regeneration because they chemically resemble bone mineral. In this study, the feasibility to manufacture CHAp/β-TCP scaffolds by pseudomorphic transformation of casted blocks of gypsum was investigated. The transformation was carried out by immersing the precursor gypsum block in 1 M (NH{sub 4}){sub 2}HPO{sub 4}/1.33 M NH{sub 4}OH solution with liquid/solid ratio of 10 mL/g and autoclaving at 120 degree centigrade and 203 kPa (2 atm) for 3 h at least. Neither shape nor dimensions significantly changed during transformation. The composition of scaffolds treated for 3 h was 70 wt.% CHAp and 30 wt.% β-TCP, and their compressive and diametral compressive strengths were 6.5 ± 0.7 and 5.3 ±0.7 MPa, respectively. By increasing the time of treatment to 6 h, the composition of the scaffold enriched in β-TCP (60 wt.% CHAp and 40 wt.% β-TCP) but its compressive and diametral compressive strengths were not significantly affected (6.7 ± 0.9 and 5.4 ± 0.6 MPa, respectively). On the basis of the results obtained, it was concluded that this route is a good approach to the manufacturing of biphasic (CHAp/β-TCP) scaffolds from previously shaped pieces of gypsum. (Author)

Application of reject of gypsum from Trindade/PE in ceramic masses formulations

International Nuclear Information System (INIS)

Lima, Thalles Confessor de; Souza, Marcondes Mendes de; Almeida, Ana Beatriz Dantas de; Farias, Debora Santos Umbelino de; Nobrega, Luiz Felipe Pereira de Medeiros; Mendes, Luciana Bezerra

2016-01-01

The mining industry is a major producer of waste is to be harmful to the environment besides not being made possible for use in producing means, since the product of economic interest has been extracted. In order to reduce this problem, this work shows the characterization of the waste generated by gypsum mining in Trindade/PE in the ceramic coating. The residue was collected, ground and sieved to #200, then was chemically characterized by XRF analysis process, to evaluate its potential to be incorporated into the formulation of ceramic material, the material studied can be used in porcelain tile formulation as a flux element for that were obtained in the laboratory ceramic bodies adding the residue then were performed physical testing of linear shrinkage, water absorption and flexural breaking strain technically order to evaluate the addition of this residue ceramic coating. (author)

Interaction of gypsum with lead in aqueous solutions

International Nuclear Information System (INIS)

Astilleros, J.M.; Godelitsas, A.; Rodriguez-Blanco, J.D.; Fernandez-Diaz, L.; Prieto, M.; Lagoyannis, A.; Harissopulos, S.

2010-01-01

Sorption processes on mineral surfaces are a critical factor in controlling the distribution and accumulation of potentially harmful metals in the environment. This work investigates the effectiveness of gypsum (CaSO 4 .2H 2 O) to sequester Pb. The interaction of gypsum fragments with Pb-bearing solutions (10, 100 and 1000 mg/L) was monitored by performing macroscopic batch-type experiments conducted at room temperature. The aqueous phase composition was periodically determined by Atomic Absorption Spectrometry (AAS), Ion Chromatography (IC) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Regardless of the [Pb aq ] initial , a [Pb aq ] final aq ] initial ≥ 100 mg/L and significantly slower (t > 1 week) for [Pb aq ] initial = 10 mg/L. Speciation calculations revealed that after a long time of interaction (1 month), all the solutions reached equilibrium with respect to both gypsum and anglesite. For [Pb aq ] initial ≥ 100 mg/L, sorption takes place mainly via the rapid dissolution of gypsum and the simultaneous formation of anglesite both on the gypsum surface and in the bulk solution. In the case of [Pb aq ] initial = 10 mg/L, no anglesite precipitation was observed, but surface spectroscopy (proton Rutherford Backscattering Spectroscopy, p-RBS) confirmed the formation of Pb-bearing surface layers on the (0 1 0) gypsum surface in this case also. This study shows that the surface of gypsum can play an important role in the attenuation of Pb in contaminated waters.

Measurement of soil moisture using gypsum blocks

DEFF Research Database (Denmark)

Friis Dela, B.

the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account......For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...

New production processes for alpha hemihydrate open up new marketing opportunities

International Nuclear Information System (INIS)

Engert, W.; Lehmkaemper, O.; Bunte, H.P.

1991-01-01

New production processes and markets for alpha hemihydrate are discussed. Utility studies concluded that lignite gypsum is harmless in terms of public and occupational health, and is technically comparable to or superior to natural gypsum by virtue of greater purity. Semi-commercial and pilot-scale studies were carried out on the use of flue gas desulfurization (FGD) gypsum for producing alpha hemihydrate, with successful results. The process enabled pure alpha hemihydrate to be produced without dihydrate or dihydrate impurities, and of a constant, uniform quality. The treatment consists of forming pressed mouldings of FGD gypsum followed by steam autoclaving, drying and milling. Agents are used to stabilize the stackable moldings, and to act as growth inhibitors during transformation of dihydrite to alpha-hemihydrate. Markets for the product are found in mining, tunneling and road building, foundation work, floor systems, as hard plaster for dental and moulding applications, for construction industry use, and as structural and non-structural material. Details are presented of the production process and marketing concepts. 12 figs

Determination of Radium 226 in mexican phosphate fertilizers and gypsum by gamma spectrometry

International Nuclear Information System (INIS)

Godinez A, M.C.

1995-01-01

The 226 Ra isotope was determined in 17, 20 and 46% m/m phosphate fertilizers and gypsum. The samples of the fertilizers were dissolved in 10% v/v nitric acid solutions. The barium sulphate method was used for the precipitation of 226 Ra. On the other hand, alkaline fusion method was used to separate the 226 Ra from gypsum. The results indicated that 226 Ra was present in the phosphate fertilizers and gypsum. The 226 Ra concentrations present in these materials were between 10 -4 - 10 -5 μg g -1 . (Author)

Experimental Shock Transformation of Gypsum to Anhydrite: A New Low Pressure Regime Shock Indicator

Science.gov (United States)

Bell, Mary S.; Zolensky, Michael E.

2011-01-01

The shock behavior of gypsum is important in understanding the Cretaceous/Paleogene event and other terrestrial impacts that contain evaporite sediments in their targets (e.g., Mars Exploration Rover Spirit detected sulfate at Gusev crater, [1]). Most interest focuses on issues of devolatilization to quantify the production of SO2 to better understand its role in generating a temporary atmosphere and its effects on climate and biota [2,3]. Kondo and Ahrens [4] measured induced radiation emitted from single crystal gypsum shocked to 30 and 40 GPa. They observed greybody emission spectra corresponding to temperatures in the range of 3,000 to 4,000 K that are a factor of 2 to 10 times greater than calculated pressure-density energy equation of state temperatures (Hugoniot) and are high enough to melt gypsum. Chen et al. [5] reported results of shock experiments on anhydrite, gypsum, and mixtures of these phases with silica. Their observations indicated little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another report of shock experiments on calcite, anhydrite, and gypsum, Badjukov et al. [6] observed only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa but have not experimentally shocked gypsum in a step-wise manner to constrain possible incipient transformation effects. Schmitt and Hornemann [7] shock loaded anhydrite and quartz to a peak pressure of 60 GPa and report the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggested that recrystallization of anhydrite grains is the result of a solid-state transformation. They concluded that significant decomposition of anhydrite requires shock pressures higher than 60 GPa. Gupta et al. [8

Comparison of Energy Dissipation, Stiffness, and Damage of Structural Oriented Strand Board (OSB, Conventional Gypsum, and Viscoelastic Gypsum Shearwalls Subjected to Cyclic Loads

Directory of Open Access Journals (Sweden)

Andrew S. Blasetti

2012-06-01

Full Text Available A key element in the seismic load resisting system of a wood framed structure is the shear wall which is typically sheathed on one side with plywood or oriented strand board (OSB and gypsum on the other. The shear capacity of gypsum sheathed shear walls is typically neglected in high seismic areas due to the susceptibility of conventional drywall screw connections to damage caused by earthquakes. The earthquake resistance of an innovative viscoelastic (VE gypsum shearwall is evaluated and compared to conventional structural and non-structural walls. Ten 8 ft × 8 ft wood framed wall specimens of three configurations [nailed-OSB, screw-gypsum, and VE polymer-gypsum] were subjected to a cyclic test protocol. The energy dissipation, stiffness, and damage characteristics of all shearwalls are reported herein. Testing results indicate the VE-gypsum walls can dissipate more energy than the OSB structural panels and 500% more energy that the conventional gypsum sheathed walls and contains a constant source of energy dissipation not seen in the structural and non-structural walls. The wall stiffness of the OSB wall degrades at a far greater rate that the VE gypsum wall and at continued cycling degrades below the VE wall stiffness. Unlike both of the conventional wall types, the VE wall showed no visible or audible signs of damage when subjected to shear displacements up to 1.

Interaction of gypsum with lead in aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Astilleros, J.M., E-mail: jmastill@geo.ucm.es [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Godelitsas, A. [Department of Mineralogy and Petrology, Faculty of Geology and Geoenvironment, University of Athens, Panepistimioupoli Zographou, 15784 Athens (Greece); Rodriguez-Blanco, J.D. [School of Earth and Environments, Faculty of Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Fernandez-Diaz, L. [Dpto. Cristalografia y Mineralogia, Universidad Complutense de Madrid, Jose Antonio Novais, 2, E-28040 Madrid (Spain); Prieto, M. [Dpto. de Geologia, Universidad de Oviedo, E-30005 Oviedo (Spain); Lagoyannis, A.; Harissopulos, S. [Tandem Accelerator Laboratory, Institute of Nuclear Physics, NCSR ' Demokritos' , GR-15310 Attiki (Greece)

2010-07-15

Sorption processes on mineral surfaces are a critical factor in controlling the distribution and accumulation of potentially harmful metals in the environment. This work investigates the effectiveness of gypsum (CaSO{sub 4}.2H{sub 2}O) to sequester Pb. The interaction of gypsum fragments with Pb-bearing solutions (10, 100 and 1000 mg/L) was monitored by performing macroscopic batch-type experiments conducted at room temperature. The aqueous phase composition was periodically determined by Atomic Absorption Spectrometry (AAS), Ion Chromatography (IC) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Regardless of the [Pb{sub aq}]{sub initial}, a [Pb{sub aq}]{sub final} < 4 mg/L was always reached. The uptake process was fast (t < 1 h) for [Pb{sub aq}]{sub initial} {>=} 100 mg/L and significantly slower (t > 1 week) for [Pb{sub aq}]{sub initial} = 10 mg/L. Speciation calculations revealed that after a long time of interaction (1 month), all the solutions reached equilibrium with respect to both gypsum and anglesite. For [Pb{sub aq}]{sub initial} {>=} 100 mg/L, sorption takes place mainly via the rapid dissolution of gypsum and the simultaneous formation of anglesite both on the gypsum surface and in the bulk solution. In the case of [Pb{sub aq}]{sub initial} = 10 mg/L, no anglesite precipitation was observed, but surface spectroscopy (proton Rutherford Backscattering Spectroscopy, p-RBS) confirmed the formation of Pb-bearing surface layers on the (0 1 0) gypsum surface in this case also. This study shows that the surface of gypsum can play an important role in the attenuation of Pb in contaminated waters.

Use of Flue Gas Desulfurization (FGD) Gypsum as a Heavy Metal Stabilizer in Contaminated Soils

Science.gov (United States)

Flue Gas Desulfurization (FGD) gypsum is a synthetic by-product generated from the flue gas desulfurization process in coal power plants. It has several beneficial applications such as an ingredient in cement production, wallboard production and in agricultural practice as a soil...

A DOC coagulant, gypsum treatment can simultaneously reduce As, Cd and Pb uptake by medicinal plants grown in contaminated soil.

Science.gov (United States)

Kim, Hyuck Soo; Seo, Byoung-Hwan; Kuppusamy, Saranya; Lee, Yong Bok; Lee, Jae-Hwang; Yang, Jae-E; Owens, Gary; Kim, Kwon-Rae

2018-02-01

The efficiency of gypsum, as a dissolved organic carbon (DOC) coagulator, for the simultaneous immobilization of two heavy metals (Cd and Pb) and one metalloid (As) in agricultural soils near an abandoned mining site was examined. The agricultural soil was defined as long-term contaminated as As (1540mgkg -1 ), Cd (55mgkg -1 ) and Pb (1283mgkg -1 ) concentrations exceeded the Korean guideline values for As (25mgkg -1 ), Cd (4mgkg -1 ), and Pb (200mgkg -1 ). Gypsum was incorporated into the contaminated soil at 3% (w/w). In comparison two commonly using immobilizing agents (lime and compost), together with a mixture (lime+gypsum) were also included in the pot trial for the cultivation of two medical plants (A. gigas and A. macrocephala) and to evaluate the effectiveness of gypsum on As, Cd and Pb immobilization. The results showed that even though pH change-induced immobilizing agents such as lime were more effective than gypsum at immobilizing Cd and Pb, addition of gypsum also effectively reduced heavy metal phytoavailability as indicated by decreases in the concentration of Cd and Pb in medicinal plants. Furthermore, gypsum and gypsum+ lime were also most effective in reducing As concentrations in both plants studied. This was mainly attributed to significant decreases in soil DOC (48-64%) when gypsum and gypsum+lime were applied to the soil. Consequently, it was concluded that enhanced DOC coagulation with gypsum, could be considered as a promising technique for the immobilization of both metals (Cd and Pb) and metalloids (As) in agricultural soils. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of EDTA and gypsum on self diffusion coefficient of zinc in alkali soil

International Nuclear Information System (INIS)

Gupta, G.N.; Deb, D.L.

1981-01-01

The effect of EDTA and gypsum application on the rate of zinc diffusion was studied in an alkali soil. Gypsum application at the rate of half gypsum requirement (GR) increased the apparent self diffusion coefficient of zinc (DaZn) and decreased the capacity factor (B) of soil. The higher rates (full GR and double GR) depressed the rate of zinc diffusion and increased the B value. Application of EDTA at the rate of 0.77 μeg -1 of soil produced 1600 and 24 fold increase in DaZn and DpZn values respectively and 100 times drop in B value. Addition of 55 ppm Zn to the soil significantly increased the DaZn and DpZn values. (author)

Gypsum karst in Italy: a review

Science.gov (United States)

De Waele, Jo; Chiarini, Veronica; Columbu, Andrea; D'Angeli, Ilenia M.; Madonia, Giuliana; Parise, Mario; Piccini, Leonardo; Vattano, Marco; Vigna, Bartolomeo; Zini, Luca; Forti, Paolo

2016-04-01

Although outcropping only rarely in Italy, gypsum karst has been described in detail since the early XXth century (Marinelli, 1917). Gypsum caves are now known from almost all Italian regions (Madonia & Forti, 2003), but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche regions), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum quarries in Piedmont (Vigna et al., 2010). During the late 80s and 90s several multidisciplinary studies have been carried out in many gypsum areas. All this work converged into a comprehensive overview in 2003 (Madonia & Forti, 2003). Further detailed studies focused on the gypsum areas of Emilia Romagna (Chiesi et al., 2010; Forti & Lucci, 2010; Demaria et al., 2012; De Waele & Pasini, 2013; Ercolani et al., 2013; Columbu et al., 2015; Lucci & Piastra, 2015; Tedeschi et al., 2015) and of Sicily (Madonia & Vattano, 2011). Sinkholes related to Permo-Triassic gypsum have been studied in Friuli Venezia Giulia (Zini et al., 2015). This presentation will review the state of the art regarding different aspects of evaporite karst in Italy focusing on the main new results. References Chiesi M., et al. (2010) - Origin and evolution of a salty gypsum/anhydrite karst spring: the case of Poiano (Northern Apennines, Italy). Hydrogeology Journal, 18, pp. 1111-1124. Columbu A. et al. (2015) - Gypsum caves as indicators of climate-driven river incision and aggradation in a rapidly uplifting region. Geology, 43(6), 539-542. Demaria D. et al. (Eds.) (2012), Le Grotte Bolognesi, GSB-USB, 431 p. De Waele J., Pasini G. (2013) - Intra-messinian gypsum palaeokarst in the northern Apennines and its palaeogeographic implications. Terra Nova 25, pp. 199-205. Ercolani M., et al. (Eds.) (2013), I Gessi e la Cave i Monte Tondo. Studio multidisciplinare di un'area carsica nella Vena del Gesso Romagnola. Memorie Ist. It. Spel. II(26), 559 p

Uranium-series dating of gypsum speleothems: methodology and examples.

Directory of Open Access Journals (Sweden)

Sanna Laura

2010-01-01

Full Text Available The analytical problems of dating gypsum speleothems with the U-series technique are reviewed. Gypsum speleothems are, in general, very low in U content, challenging the limits of detection methods. Various approaches to dissolving gypsum and isolation of actinides from the matrix include ion-pairing dissolution with magnesium salts and using nitric acid. The most precise dating technique is Thermal Ionization Mass Spectrometry (TIMS, combined with Fe(OH3 scavenging and anionic exchange chromatography. Less satisfactory, but much quicker, is direct retention of actinides from HNO3 by means of TRU resin and MC-ICP-MS detection. We have tested these methods on gypsum speleothems from the Sorbas karst in Spain and from the Naica caves in Mexico.

Mechanical properties of gypsum board at elevated temperatures

Science.gov (United States)

S.M. Cramer; O.M. Friday; R.H. White; G. Sriprutkiat

2003-01-01

Gypsum board is a common fire barrier used in house and general building construction. Recently, evaluation of the collapses of the World Trade Center Towers highlighted the potential role and failure of gypsum board in containing the fires and resisting damage. The use of gypsum board as primary fire protection of light-flame wood or steel construction is ubiquitous....

Use of gypsum residues as a corrective for saline-sodic soil

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Paulo Medeiros dos Santos

2014-03-01

Full Text Available One of the hugest problems faced by the civil construction sector is the final destination of residues, especially gypsum, which presents recycling restrictions. However, these residues present a high amount of calcium in their composition, and can be alternatively used for replacing mined gypsum as a saline-sodic soil corrective. This study aimed at evaluating the efficiency of gypsum residues from the civil construction, when compared to mined gypsum, for correcting a saline-sodic soil. A randomized blocks design was used, in a factorial arrangement consisting of two kinds of corrective (gypsum residue and mined gypsum and five leaching depths (0.5, 1.0, 1.5, 2.0 and 2.5 times the soil pores volume, with three replications. Electric conductivity, soluble cations and sodium adsorption ratio were evaluated in the soil saturation extract. The use of gypsum residue proved to be effective in leaching salts and soluble sodium in saline-sodic soil, and can be recommended as a calcium source for recovering from sodicity.

Mineral of the month: gypsum

Science.gov (United States)

Founie, Alan

2004-01-01

The earliest known use of gypsum as a building material was in Anatolia (in what is now Turkey) around 6000 B.C. It has been found on the interiors of the great pyramids in Egypt, which were erected in about 3700 B.C. Now an average new American home contains more than 7 metric tons of gypsum in the form of more than 6,000 square feet of wallboard.

Investigation of Parameters Affecting Gypsum Dewatering Properties in a Wet Flue Gas Desulphurization Pilot Plant

DEFF Research Database (Denmark)

Hansen, Brian Brun; Kiil, Søren

2012-01-01

of impurities (0.002 M Al2F6; 50 g quartz/L; 0.02 M Al3+, and 0.040 M Mg2+) were investigated. In addition, slurry from a full-scale wet FGD plant, experiencing formation of flat shaped crystals and poor gypsum dewatering properties, was transferred to the pilot plant to test if the plant would now start...... to time. In this work, the particle size distribution, morphology, and filtration rate of wet FGD gypsum formed in a pilot-scale experimental setup, operated in forced oxidation mode, have been studied. The influence of holding tank residence time (10–408 h), solids content (30–169 g/L), and the presence...... to produce low quality gypsum. The crystals formed in the pilot plant, on the basis of the full-scale slurry did, however, show acceptable filtration rates and crystal morphologies closer to the prismatic crystals from after pilot plant experiments with demineralized water. The gypsum slurry filtration rates...

Gypsum addition to soils contaminated by red mud: implications for aluminium, arsenic, molybdenum and vanadium solubility.

Science.gov (United States)

Lehoux, Alizée P; Lockwood, Cindy L; Mayes, William M; Stewart, Douglas I; Mortimer, Robert J G; Gruiz, Katalin; Burke, Ian T

2013-10-01

Red mud is highly alkaline (pH 13), saline and can contain elevated concentrations of several potentially toxic elements (e.g. Al, As, Mo and V). Release of up to 1 million m(3) of bauxite residue (red mud) suspension from the Ajka repository, western Hungary, caused large-scale contamination of downstream rivers and floodplains. There is now concern about the potential leaching of toxic metal(loid)s from the red mud as some have enhanced solubility at high pH. This study investigated the impact of red mud addition to three different Hungarian soils with respect to trace element solubility and soil geochemistry. The effectiveness of gypsum amendment for the rehabilitation of red mud-contaminated soils was also examined. Red mud addition to soils caused a pH increase, proportional to red mud addition, of up to 4 pH units (e.g. pH 7 → 11). Increasing red mud addition also led to significant increases in salinity, dissolved organic carbon and aqueous trace element concentrations. However, the response was highly soil specific and one of the soils tested buffered pH to around pH 8.5 even with the highest red mud loading tested (33 % w/w); experiments using this soil also had much lower aqueous Al, As and V concentrations. Gypsum addition to soil/red mud mixtures, even at relatively low concentrations (1 % w/w), was sufficient to buffer experimental pH to 7.5-8.5. This effect was attributed to the reaction of Ca(2+) supplied by the gypsum with OH(-) and carbonate from the red mud to precipitate calcite. The lowered pH enhanced trace element sorption and largely inhibited the release of Al, As and V. Mo concentrations, however, were largely unaffected by gypsum induced pH buffering due to the greater solubility of Mo (as molybdate) at circumneutral pH. Gypsum addition also leads to significantly higher porewater salinities, and column experiments demonstrated that this increase in total dissolved solids persisted even after 25 pore volume replacements. Gypsum

Gypsum crystals observed in experimental and natural sea ice

DEFF Research Database (Denmark)

Geilfus, Nicolas-Xavier; Galley, Ryan; Cooper, Marc

2013-01-01

, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the “Gitterman pathway” where gypsum is predicted to precipitate. The occurrence...

Testing CO2 Sequestration in an Alkaline Soil Treated with Flue Gas Desulfurization Gypsum (FGDG)

Science.gov (United States)

Han, Y.; Tokunaga, T. K.

2012-12-01

Identifying effective and economical methods for increasing carbon storage in soils is of interest for reducing soil CO2 fluxes to the atmosphere in order to partially offset anthropogenic CO2 contributions to climate change This study investigates an alternative strategy for increasing carbon retention in soils by accelerating calcite (CaCO3) precipitation and promoting soil organic carbon (SOC) complexation on mineral surfaces. The addition of calcium ion to soils with pH > 8, often found in arid and semi-arid regions, may accelerate the slow process of calcite precipitation. Increased ionic strength from addition of a soluble Ca source also suppresses microbial activity which oxidizes SOC to gaseous CO2. Through obtaining C mass balances in soil profiles, this study is quantifying the efficiency of gypsum amendments for mitigating C losses to the atmosphere. The objective of this study is to identify conditions in which inorganic and organic C sequestration is practical in semi-arid and arid soils by gypsum treatment. As an inexpensive calcium source, we proposed to use flue gas desulfurization gypsum (FGDG), a byproduct of fossil fuel burning electric power plants. To test the hypothesis, laboratory column experiments have been conducted in calcite-buffered soil with addition of gypsum and FGDG. The results of several months of column monitoring are demonstrating that gypsum-treated soil have lowered amounts of soil organic carbon loss and increased inorganic carbon (calcite) production. The excess generation of FGDG relative to industrial and agricultural needs, FGDG, is currently regarded as waste. Thus application of FGDG application in some soils may be an effective and economical means for fixing CO2 in soil organic and inorganic carbon forms.Soil carbon cycle, with proposed increased C retention by calcite precipitation and by SOC binding onto soil mineral surfaces, with both processes driven by calcium released from gypsum dissolution.

Initiation and growth of gypsum piercement structures in the Zechstein Basin

Science.gov (United States)

Williams-Stroud, S. C.; Paul, J.

1997-01-01

The importance of tectonic processes in initiating halite diapirs has become much better understood in recent years. Less well understood is the development of diapiric structures involving rocks composed predominantly of gypsum. Below about 1000 m, gypsum dehydrates to anhydrite, which often obscures primary sedimentary textures. If the strain associated with diapiric rise in the rock induces the transition to anhydrite, obliteration of primary features in the gypsum can be expected. In our study, we infer that the diapiric movement in the Werra Anhydrite member of cycle 1 of the Zechstein Formation of Europe occurred before the initial transition of gypsum to anhydrite based on the presence of pseudomorphs of bedded primary gypsum crystals, the overburden lithologies and depositional environment, and the mechanical properties of gypsum, anhydrite and carbonate rocks. Faulting and differential loading of a shallow overburden were the key components in initiating the gypsum diapirism. The transition to anhydrite occurred after burial and after cessation of diapirism. In comparison, the diapirism of calcium sulfate of the Leine Anhydrite into the Leine Halite members of cycle 3 of the Zechstein Formation probably occurred much later after burial and appears to have been triggered by halite diapirism, which in turn triggered the dehydration reaction, causing the calcium sulfate to become the incompetent phase relative to the halite. Published by Elsevier Science Ltd.

Effect of temperature and concentration principle on gypsum scaling in desalination units

International Nuclear Information System (INIS)

Ben Ahmed, Samia; Tlili, Mohamed; Ben Amor, Mohamed

2009-01-01

Tunisia (North Africa) is currently confronted to the crucial problem of the public, agricultural and industrial feed water supply, in particular in the center and south areas. Production of fresh water by seawater and brackish water desalination has proved to be an alternative for these regions. However, all the desalination processes are based on the concentration principle of waters already presented higher salinity. So, scale problem can occurs by the accumulation of minerals such as CaCO 3 and CaSO 4 . These salts form hard and strongly adhering deposits on the surfaces and their formation is favoured by the decrease of their solubility with increasing temperature. The main object of this investigation is the study and the control of calcium sulphate deposition causes and conditions in the thermal desalination plant. For this purpose, the effect of different water temperatures (30-90 degree) and saturation states (3-10), on homogeneous nucleation and growth of gypsum, variety usually met, was examined. Gypsum was precipitated by mixing aqueous CaCl 2 and Na 2 SO 4 solutions. It was found that, with increasing temperature or supersaturation, the induction time decreases and the growth rate increases. At the same saturation state, the effect of temperature on reducing induction time is more significant for T<50 degree whereas the growth rate of gypsum crystals is more influenced when the temperature exceeds 50 degree. This value can be considered as a critical temperature; once reached the gypsum scaling threat becomes serious. By using classical nucleation theory, the interfacial tension and the nucleation rate values were estimated. It was shown that the interfacial tension is, as well, temperature dependent. The calculation of nucleation rate showed that: i) by increasing temperature, the number of formed nuclei does not change. The effect of this parameter is limited at the kinetic of formation and growth of these nuclei, ii) the water concentration

Mineral potential of clays that cover the gypsum deposits in Araripina-PE region

International Nuclear Information System (INIS)

Lira, B.B.; Anjos, I.F. dos; Rego, S.A.B.C.

2011-01-01

In the present work the applicability of the clays that cover the deposits of Gypsum Plaster in the region of Araripina - PE for use as the ceramic pigments and for bricks production in the red ceramic industry was analyzed. The clay minerals contained the illite, kaolinite and smectite, with high proportion of the last one. The possibility of industrial application of this mineral clay is considerable; however, the mining industries that mine and process the gypsum in the region do not take the clays into account as the potential mineral. In general, industries use the clay minerals in manufacturing processes or as key raw materials, or as the alternatives for some kinds of the chemical processing industries. This paper aims to highlight the potential of materials that cover the deposits of gypsum in reference. The material sampled from different deposit layers was characterized and the physical treatment of ore was applied. The results showed that the material analyzed can be used in various kinds of industry, such as the production of natural ceramic pigments. (author)

Dehydration reactions of gypsum: A neutron and X-ray diffraction study

Science.gov (United States)

Abriel, W.; Reisdorf, K.; Pannetier, J.

1990-03-01

The kinetics of the dehydration of gypsum was investigated by powder diffraction methods. Using the incoherent scattering effect of H with the neutron beam, the background intensity as a measure of the water content was checked in the temperature range 295-623 K. The superposed Bragg peaks yielded four major phases: Gypsum, subhydratesCaSO 4(H 2O) x (1 > x > 0),AIII-CaSO 4, AII-CaSO 4. For the subhydrates a maximum water content of x > = 0.74was determined. A different kinetic was found using Guinier X-ray technique with the heated sample prepared on a thin foil. Only with high local H 2O steam pressure, produced in the comparable larger sample container of the neutron diffraction experiment, could this high H 2O occupation of the subhydrate tunnel structure be found. A topotactic mechanism can describe the phase transitions for this reaction.

Urea Hydrolysis and Calcium Carbonate Precipitation in Gypsum-Amended Broiler Litter.

Science.gov (United States)

Burt, Christopher D; Cabrera, Miguel L; Rothrock, Michael J; Kissel, D E

2018-01-01

Broiler () litter is subject to ammonia (NH) volatilization losses. Previous work has shown that the addition of gypsum to broiler litter can increase nitrogen mineralization and decrease NH losses due to a decrease in pH, but the mechanisms responsible for these effects are not well understood. Therefore, three laboratory studies were conducted to evaluate the effect of gypsum addition to broiler litter on (i) urease activity at three water contents, (ii) calcium carbonate precipitation, and (iii) pH. The addition of gypsum to broiler litter increased ammonium concentrations ( litter pH by 0.43 to 0.49 pH units after 5 d ( litter only increased on Day 0 for broiler litter with low (0.29 g HO g) and high (0.69 g HO g) water contents, and on Day 3 for litter with medium (0.40 g HO g) water content ( litter with gypsum also caused an immediate decrease in litter pH (0.22 pH units) due to the precipitation of calcium carbonate (CaCO) from gypsum-derived calcium and litter bicarbonate. Furthermore, as urea was hydrolyzed, more urea-derived carbon precipitated as CaCO in gypsum-treated litter than in untreated litter ( litter with gypsum favors the precipitation of CaCO, which buffers against increases in litter pH that are known to facilitate NH volatilization. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

occurrence and geochemistry of nafada gypsum, north-eastern nigeria

African Journals Online (AJOL)

DJFLEX

2010-03-18

Mar 18, 2010 ... The container was placed in a. “HERZOG” palletizing machine for 10 seconds after which a pellet was produced. The procedure was repeated for each gypsum sample. Each pellet was analyzed for SiO2, Al2O3, CaO, MgO, SO3, K2O, Na2O,. MgCO3, combine water and purity, using X-ray spectrometer.

The Growth of Gypsum in the Presence of Hexavalent Chromium: A Multiscale Study

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Juan Morales

2016-03-01

Full Text Available The sorption of dissolved inorganic pollutants into the structure of minerals is an important process that controls the mobility and fate of these pollutants in the Earth’s crust. It also modifies the surface structure and composition of the host mineral, affecting its crystallization kinetics. Here, we investigate the effect of hexavalent chromium, Cr(VI, on the nucleation and growth of gypsum by conducting two types of experiments: (i in situ atomic force microscopy (AFM observations of the growth of gypsum {010} surfaces in the presence of Cr(VI and (ii gypsum precipitation experiments by mixing aqueous solutions containing variable amounts of Cr(VI. Gypsum precipitation is progressively delayed when occurring from solutions bearing increasing Cr(VI concentrations. Chemical analyses of gypsum precipitates show that gypsum incorporates small Cr(VI amounts that correlate with the content of this ion in the aqueous solution. Gypsum cell parameters variation reflects this incorporation. At the molecular scale, Cr(VI induces a slowdown of step advance rates on gypsum {010} surfaces accompanied by the roughening of nanostep edges and the so-called “template effect”. This effect involves the reproduction of the original nanotopography after the completion of individual advancing monolayers and appears as a general nanoscale phenomenon occurring during growth of solid solutions from aqueous solutions even in the case of compositionally-restricted solid solutions.

The production and utilization of by-product agricultural fertilizer from flue gases

International Nuclear Information System (INIS)

Frank, N.W.; Hirano, S.

1992-01-01

The electron-beam process is one of the most effective methods for removing SO 2 and NO X from industrial flue gases and producing a usable by-product. This paper surveys the potential for production and consumption of alternative, usable, commercial by-products, in conjunction with major reductions in the inventory of emissions of SO 2 and NO X . An examination is made of the important limitations in the annual consumptive use or price of and/or net revenues from commonplace, electric utility, by-product types such as gypsum, sulfuric acid, etc. A principal focus of the work is an analysis and quantification of the major large-scale, growing and profitable markets for utility solid wastes that can be generated in agricultural fertilizer forms, including ammonium sulfate and other compounds that are available through stack-gas cleaning operations at large, coal-fired boilers. Cost study data is arranged to define the impact of commercial by-product yield and revenue on the economics of full scale SO 2 and NO X emission reduction activity. (author)

ESR Studies and Dating of Egyptian Gypsum at Ras Mala'ab, Sinai, Egypt

International Nuclear Information System (INIS)

Abdel-Monem, A. A.; Abdei-Razek, Y. A.; Rasheed, N. M.; Hassan, G.M.; Eissa, H.M.; El-Morsy, M.

2007-01-01

A gypsum sample from the famous gypsum-anhydrite evaporitic deposit composing the Ras Mala'ab Formation, Upper Miocene, occurring at Ras Mala'ab, on the east coast of the Gulf of Suez, was subjected to (ESR) dosimetric studies. Also, (ESR) was used to date the formation or most recent recrystallization of that gypsum. The gypsum derivative (ESR) spectrum is characterized by the large broad Fe 2+ signal (g=2.50) and HF-sixtet Mn 2+ signals. Only the characteristic gypsum signal (G l, g=2.0040) was detected between the third and fourth lines of the HF-Mn 2+ which is attributed to the electron-center SO 3 - . This signal was sensitive to artificial γ-irradiation and showed significant enhancement using a γ-dose of 550 Gy. Also, the signal was very stable up to 400 o C. The gypsum sample with a total dose (TD) of 1500 Gy, determined graphically by extrapolating the linear relationship between defect concentration and the artificial γ-doses for (G l, g=2.0040) and an annual dose (D) due to cosmic rays (0.3 mGy), yielded an age of 5.00 Ma. This could mean the age of formation or latest recrystallization of this gypsum deposit. The geologic age assignment of the Ras Mala'ab Group including the evaporitic gypsum unit, is Middle to Late Miocene. It is directly overlain by the Pliocene elastics at the locality of Ras Mala'ab. This might suggest that these evaporitic gypsum facies represent the top of the Miocene in the Gulf of Suez area, since the Miocene-Pliocene boundary is now put at 5.00-5.50 Ma ago. Therefore, the ESR age of the Ras Mala'ab gypsum is consistent with the geologic age assignment

Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 1, Executive summary

Energy Technology Data Exchange (ETDEWEB)

Smith, Kevin [Dravo Technology Center, Pittsburgh, PA (United States); Beeghly, Joel H. [Dravo Technology Center, Pittsburgh, PA (United States)

2000-11-30

About 30 electric utility units with a combined total of 15,000 MW utilize magnesium enhanced lime flue gas desulfurization (FGD) systems. A disadvantage of this and other inhibited or natural oxidation wet FGD systems is the capital and operating cost associated with landfill disposal of the calcium sulfite based solids. Fixation to stabilize the solids for compaction in a landfill also consumes fly ash that otherwise may be marketable. This Executive Summary describes efforts to dewater the magnesium hydroxide and gypsum slurries and then process the solids into a more user friendly and higher value form. To eliminate the cost of solids disposal in its first generation Thiosorbic® system, the Dravo Lime Company developed the ThioClear® process that utilizes a magnesium based absorber liquor to remove S0₂ with minimal suspended solids. Magnesium enhanced lime is added to an oxidized bleed stream of thickener overflow (TOF) to produce magnesium hydroxide [Mg(OH)₂] and gypsum (CaS0₄ • 2H₂0), as by-products. This process was demonstrated at the 3 to 5 MW closed loop FGD system pilot plant at the Miami Fort Station of Cinergy, near Cincinnati, Ohio with the help of OCDO Grant Agreement CDO/D-91-6. A similar process strictly for'recovery and reuse of Mg(OH)₂ began operation at the Zimmer Station of Cinergy in late 1994 that can produce 900 pounds of Mg(OH)₂ per hour and 2,600 pounds of gypsum per hour. This by-product plant, called the Zimmer Slipstream Magnesium Hydroxide Recovery Project Demonstration, was conducted with the help of OCDO Grant Agreement CDO/D-921-004. Full scale ThioClear® plants began operating in 1997 at the 130 MW Applied Energy Services plant, in Monaca, PA, and in year 2000 at the 1,330 MW Allegheny Energy Pleasants Station at St. Marys, WV.

Collapse susceptibility mapping in karstified gypsum terrain (Sivas basin - Turkey) by conditional probability, logistic regression, artificial neural network models

Science.gov (United States)

Yilmaz, Isik; Keskin, Inan; Marschalko, Marian; Bednarik, Martin

2010-05-01

This study compares the GIS based collapse susceptibility mapping methods such as; conditional probability (CP), logistic regression (LR) and artificial neural networks (ANN) applied in gypsum rock masses in Sivas basin (Turkey). Digital Elevation Model (DEM) was first constructed using GIS software. Collapse-related factors, directly or indirectly related to the causes of collapse occurrence, such as distance from faults, slope angle and aspect, topographical elevation, distance from drainage, topographic wetness index- TWI, stream power index- SPI, Normalized Difference Vegetation Index (NDVI) by means of vegetation cover, distance from roads and settlements were used in the collapse susceptibility analyses. In the last stage of the analyses, collapse susceptibility maps were produced from CP, LR and ANN models, and they were then compared by means of their validations. Area Under Curve (AUC) values obtained from all three methodologies showed that the map obtained from ANN model looks like more accurate than the other models, and the results also showed that the artificial neural networks is a usefull tool in preparation of collapse susceptibility map and highly compatible with GIS operating features. Key words: Collapse; doline; susceptibility map; gypsum; GIS; conditional probability; logistic regression; artificial neural networks.

The study of Influencing Maintenance Factors on Failures of Two gypsum Kilns by Failure Modes and Effects Analysis (FMEA

Directory of Open Access Journals (Sweden)

Iraj Alimohammadi

2014-06-01

Full Text Available Developing technology and using equipment in Iranian industries caused that maintenance system would be more important to use. Using proper management techniques not only increase the performance of production system but also reduce the failures and costs. The aim of this study was to determine the quality of maintenance system and the effects of its components on failures of kilns in two gypsum production companies using Failure Modes and Effects Analysis (FMEA. Furthermore the costs of failures were studied. After the study of gypsum production steps in the factories, FMEA was conducted by the determination of analysis insight, information gathering, making list of kilns’ component and filling up the FMEA’s tables. The effects of failures on production, how to fail, failure rate, failure severity, and control measures were studied. The evaluation of maintenance system was studied by a check list including questions related to system components. The costs of failures were determined by refer in accounting notebooks and interview with the head of accounting department. It was found the total qualities of maintenance system in NO.1 was more than NO.2 but because of lower quality of NO.1’s kiln design, number of failures and their costs were more. In addition it was determined that repair costs in NO.2’s kiln were about one third of NO.1’s. The low severity failures caused the most costs in comparison to the moderate and low ones. The technical characteristics of kilns were appeared to be the most important factors in reducing of failures and costs.

Soil management and application of agricultural gypsum in a Planosol for soybean cultivation

OpenAIRE

Marchesan, Enio; Tonetto, Felipe; Teló, Gustavo Mack; Coelho, Lucas Lopes; Aramburu, Bruno Behenck; Trivisiol, Vinicius Severo

2017-01-01

ABSTRACT: This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage res...

Direct and indirect dating of gypsum occurrences in deserts using luminescence methods

International Nuclear Information System (INIS)

Nagar, Y.C.; Juyal, N.; Singhyi, A.K.; Kocurek, G.; Wadhawan, S.K.

2005-01-01

In the present study we have made an attempt to directly date gypsum or provide indirect age estimate for gypsum formation through dating the associated sediments (quartz) using the luminescence dating technique. In the direct dating of gypsum, we explored the Optically Stimulated Luminescence (OSL) and Thermally Stimulated Luminescence (TL) behaviour of gypsum. The associated sediments (indirect dating) were dated using the traces of quartz extract from gypsum (concentration 0.1% ) and the underlying and overlying quartz sand in playa

Effects of gypsum and bulk density on neutron probe calibration curves

International Nuclear Information System (INIS)

Arslan, Awadis; Razzouk, A.K.

1993-10-01

The effects of gypsum and bulk density on the neutron probe calibration curve were studied in the laboratory and in the field. The effect of bulk density was negligible for the soil studied in the laboratory, while it was significant for the field calibration. An increase in the slope of moisture content on a volume basis vs. count ratio with increasing gypsum content at the soil was observed in the laboratory calibration. A simple method for correction of the calibration curve for gypsum content was adopted to obtain a specific curve for each layer. The adapted method requires the gypsum fraction to be estimated for each layer and then incorporated in the calibration curve to improve the coefficient of determination. A field calibration showed an improvement of the determination coefficient by introducing bulk density and gypsum fraction, in addition to count ratio using moisture content on a volume basis as a dependent variable in multi linear regression analysis. The same procedure was successful with variable gravel fractions. (author). 18 refs., 3 figs., 2 tabs

Occurrence and geochemistry of Nafada Gypsum, north-eastern ...

African Journals Online (AJOL)

Gypsum deposits occur in numerous locations within the Senonian Fika Shale at Nafada, northeastern Nigeria. Geologic investigations at Baro Winde and Wuro Dabo mines indicate the occurrence of three varieties of gypsum namely, Balatino laminated, Alabaster and Satin Spar. These are interlayered within shale and ...

Gypsum Formation during the Messinian Salinity Crisis: an Alternative Model

Science.gov (United States)

Grothe, A.; Krijgsman, W.; Sangiorgi, F.; Vasiliev, I.; Baak, C. V.; Wolthers, M.; Stoica, M.; Reichart, G. J.; Davies, G.

2016-12-01

During the Messinian Salinity Crisis (MSC; 5.97 - 5.33 Myr ago), thick packages of evaporites (gypsum and halite) were deposited in the Mediterranean Basin. Traditionally, the occurrence of these evaporites is explained by the so-called "desiccation-model", in which evaporites are considered to result from a (partly) desiccated basin. In the last decade, it was thought that changes in the Mediterranean-Atlantic connectivity could explain the formation of gypsum. Stable isotope studies, however, show that the gypsum formed under influence of large freshwater input. Here we present new strontium isotope data from two well-dated Messinian sections in the Black and Caspian Seas. Our Sr isotope records suggest a persistent Mediterranean-Black Sea connection throughout the salinity crisis, which implies a large additional freshwater source to the Mediterranean. We claim that low saline waters from the Black Sea region are a prerequisite for gypsum formation in the Mediterranean and speculate about the mechanisms explaining this apparent paradox.

Pre-contamination of new gypsum wallboard with potentially harmful fungal species

DEFF Research Database (Denmark)

Andersen, Birgitte; Dosen, Ina; Lewinska, Anna Malgorzata

2017-01-01

Gypsum wallboard is a popular building material, but is also very frequently overgrown by Stachybotrys chartarum after severe and/or undetected water damage. The purpose of this study was to determine whether Stachybotrys and other fungi frequently isolated from wet gypsum wallboard are already...

Producing ammonium sulfate from flue gas desulfurization by-products

Science.gov (United States)

Chou, I.-Ming; Bruinius, J.A.; Benig, V.; Chou, S.-F.J.; Carty, R.H.

2005-01-01

Emission control technologies using flue gas desulfurization (FGD) have been widely adopted by utilities burning high-sulfur fuels. However, these technologies require additional equipment, greater operating expenses, and increased costs for landfill disposal of the solid by-products produced. The financial burdens would be reduced if successful high-volume commercial applications of the FGD solid by-products were developed. In this study, the technical feasibility of producing ammonium sulfate from FGD residues by allowing it to react with ammonium carbonate in an aqueous solution was preliminarily assessed. Reaction temperatures of 60, 70, and 80??C and residence times of 4 and 6 hours were tested to determine the optimal conversion condition and final product evaluations. High yields (up to 83%) of ammonium sulfate with up to 99% purity were achieved under relatively mild conditions. The optimal conversion condition was observed at 60??C and a 4-hour residence time. The results of this study indicate the technical feasibility of producing ammonium sulfate fertilizer from an FGD by-product. Copyright ?? Taylor & Francis Inc.

Triple oxygen isotope systematics of structurally bonded water in gypsum

Science.gov (United States)

Herwartz, Daniel; Surma, Jakub; Voigt, Claudia; Assonov, Sergey; Staubwasser, Michael

2017-07-01

The triple oxygen isotopic composition of gypsum mother water (gmw) is recorded in structurally bonded water in gypsum (gsbw). Respective fractionation factors have been determined experimentally for 18O/16O and 17O/16O. By taking previous experiments into account we suggest using 18αgsbw-gmw = 1.0037; 17αgsbw-gmw = 1.00195 and θgsbw-gmw = 0.5285 as fractionation factors in triple oxygen isotope space. Recent gypsum was sampled from a series of 10 ponds located in the Salar de Llamara in the Atacama Desert, Chile. Total dissolved solids (TDS) in these ponds show a gradual increase from 23 g/l to 182 g/l that is accompanied by an increase in pond water 18O/16O. Gsbw falls on a parallel curve to the ambient water from the saline ponds. The offset is mainly due to the equilibrium fractionation between gsbw and gmw. However, gsbw represents a time integrated signal biased towards times of strong evaporation, hence the estimated gmw comprises elevated 18O/16O compositions when compared to pond water samples taken on site. Gypsum precipitation is associated with algae mats in the ponds with lower salinity. No evidence for respective vital effects on the triple oxygen isotopic composition of gypsum hydration water is observed, nor are such effects expected. In principle, the array of δ18Ogsbw vs. 17Oexcess can be used to: (1) provide information on the degree of evaporation during gypsum formation; (2) estimate pristine meteoric water compositions; and (3) estimate local relative humidity which is the controlling parameter of the slope of the array for simple hydrological situations. In our case study, local mining activities may have decreased deep groundwater recharge, causing a recent change of the local hydrology.

Determination of Ra-226 and Th-232 in samples of natural phosphates, industrial gypsums and surface soils by gamma spectrometry

International Nuclear Information System (INIS)

Pessenda, L.C.R.; Nascimento Filho, V.F. do; Nadai, E.A. de; Barros Ferraz, E.S. de; Sao Paulo Univ., Piracicaba

1988-01-01

The natural radioactivity in Ra-226 and Th-232 in samples of natural phosphates, industrial gypsums (phosphogypsums) and surface soils of different regions was measured by γ-ray spectrometry. The majority of phosphates and gypsums examined showed significantly higher values than soils, mainly in relation to Ra-226 activity. The activity ranges found for phosphates, gypsums and soils were: 79.1 - 3180 Bq/kg, 56.3 - 986.6 Bq/kg, 8.8 - 54.3 Bq/kg for Ra-226 and 33.6 - 1450.3 Bq/kg; 17.4 - 130,1 Bq/kg, 9.8 - 108.9 Bq/kg for Th-232, respectively. (author) [pt

Mechanism of gypsum hydration

Directory of Open Access Journals (Sweden)

Pacheco, G.

1991-06-01

Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

Hydrology of marginal evaporitic basins during the Messinian Salinity Crisis: isotopic investigation of gypsum deposits

Science.gov (United States)

El Kilany, Aida; Caruso, Antonio; Dela Pierre, Francesco; Natalicchio, Marcello; Rouchy, Jean-Marie; Pierre, Catherine; Balter, Vincent; Aloisi, Giovanni

2016-04-01

The deposition of gypsum in Messinian Mediterranean marginal basins is controlled by basin restriction and the local hydrological cycle (evaporation/precipitation rates and relative importance of continental vs marine water inputs). We are using the stable isotopic composition of gypsum as a proxy of the hydrological cycle that dominated at the moment of gypsum precipitation. We studied the Messinian Caltanissetta (Sicily) and Tertiary Piedmont (north western Italy) basins where we carried out a high-resolution isotopic study of gypsum layers composing gypsum-marl cycles. These cycles are thought to be the sedimentary expression of astronomical precession cycles, lasting approximately 20 kyr, during which the marginal basins experienced a succession of arid and a wet conditions. We determined the isotopic composition of gypsum hydration water (18O and D), of the sulphate ion (34S, 18O) and of Strontium (87/86Sr), all of which are potentially affected by the hydrological cycle. In our samples, the mother water from which gypsum precipitated is considerably lighter (-4.0 micro-scale. This is an essential step in interpreting the isotopic signals of gypsum because we can expect the 18O and D composition of Messinian continental input to be not too dissimilar from that of modern meteoric waters involved in diagenetic processes.

Lime and gypsum application on the wheat crop

Directory of Open Access Journals (Sweden)

Caires Eduardo Fávero

2002-01-01

Full Text Available Root growth and crop yield can be affected by chemical modifications of the soil profile owing to lime and gypsum applications. A field trial was carried out on a dystrophic Clayey Rhodic Hapludox at Ponta Grossa, PR, Brazil, aiming to evaluate lime (without or with incorporation into the soil and gypsum effects on root growth, mineral nutrition and grain yield of wheat (cv. OR 1. A randomized complete block design was used, with three replications, in a split-plot experiment. Treatments with dolomitic limestone (without lime and 4.5 t ha-1 of lime applied on the surface, in total rate and 1/3 of the requirement per year during 3 years, or incorporated into the soil were applied in July 1998 (main plots and the rates of gypsum (0, 3, 6 and 9 t ha-1 in October 1998 (subplots. Wheat was evaluated in the 2000 winter season. In conditions of water deficit absence, there was no limitation in root growth in depth, for exchangeable Ca of 6 mmol c dm-3. Lime incorporation of lime increased the Mg concentration in the leaves, but wheat yield was not influenced by the correction of soil acidity through liming treatments. Gypsum increased the concentrations of Ca and S in wheat leaves, with significant effects on grain yield. The critical level of S-SO4(2- in the 0-20 cm soil layer, extracted by ammonium acetate 0.5 mol L-1 in acetic acid 0.25 mol L-1, was 25.8 mg dm-3.

Chemical properties of an Oxisol after gypsum application

Directory of Open Access Journals (Sweden)

Victor Roncaratti de Moraes

2016-10-01

Full Text Available Gypsum utilization is a critical practice in agriculture because of the high solubility and consequent relative neutralization of subsurface toxic aluminum. However, it has been observed that in most cases, gypsum is being randomly utilized without scientifically established parameters or even the need to use it as a soil amendment at all. The objective of this study was to evaluate the chemical composition and electrical conductivity of an Oxisol’s saturation extract under different gypsum doses (0, 1.0, 2.0, 4.0, and 8.0 Mg ha-1. This experiment was conducted in a greenhouse environment. Soil columns (V = 1.57 dm3 were filled with sifted (2 mm soil collected from the upper layer (0-20 cm. The experimental design adopted was completely randomized with five repetitions. The treatments consisted of a 5 × 2 factorial through five gypsum doses (0.0, 1.0, 2.0, 4.0, and 8.0 Mg ha-1 of gypsum consisting of 224.1 g kg-1 S, 314.8 g kg-1 CaO, and 7 g kg-1 P2O5 and two depth evaluations (0-10 and 10-20 cm. After the treatments, soil from both 0-10 cm and 10-20 cm layers was removed from the columns, sifted once (2 mm, and subjected to vacuum extraction to assess the saturation extract. The data acquired was processed and submitted to variance analysis (when due and adjusted to regression equations when statistically relevant. Significant increases were observed for Ca, Mg, K, P, and S, although Al, Si, and pH presented no statistically significant difference. The electrical conductivity value of this soil in particular is directly related to the gypsum dose.

Development of gypsum alteration on marble and limestone

Science.gov (United States)

McGee, E.S.

1996-01-01

Blackened alteration crusts of gypsum plus particulates that form on sheltered areas on marble and limestone buildings pose a challenge for rehabilitation and cleaning. Fresh marble and limestone samples exposed at monitored exposure sites present conditions of simple geometry and well-documented exposures but have short exposure histories (one to five years). The gypsum alteration crusts that develop on these samples provide insight into the early stages and rate of alteration crust formation. Alteration crusts from buildings give a longer, but less well known exposure history and present much more complex surfaces for gypsum accumulation. Integrated observations and measurements of alteration crusts from exposure samples and from buildings identify four factors that are important in the formation and development of alteration crusts on marble and limestone: (1) pollution levels, (2) exposure to rain or washing, (3) geometry of exposure of the stone surface, and (4) permeability of the stone. The combination of these factors contributes to both the distribution and the physical characteristics of the gypsum crusts which may affect cleaning decisions.

Gypsum-anhydrites in 2 Ga Vempalle Formation, Cuddapah basin ...

Indian Academy of Sciences (India)

69

In fact high solubility in water leads to removal of gypsum in suficial environment. ... with presence of evaporite gypsum in the upper as well as lower part of the ..... created with shallow inlet or a slightly permeable seal with main water body.

Results using flue gas desulfurization gypsum in soilless substrates for greenhouse crops

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Recent availability of Flue Gas Desulfurization gypsum (FGDG) has led to interested in its possible use in horticulture greenhouse production. Three studies were conducted to determine the effects of increasing rates of FGDG on six greenhouse crops. In the first study, substrates (6:1 pine bark:san...

A low-temperature ductile shear zone: The gypsum-dominated western extension of the brittle Fella-Sava Fault, Southern Alps.

Science.gov (United States)

Bartel, Esther Maria; Neubauer, Franz; Heberer, Bianca; Genser, Johann

2014-12-01

Based on structural and fabric analyses at variable scales we investigate the evaporitic gypsum-dominated Comeglians-Paularo shear zone in the Southern Alps (Friuli). It represents the lateral western termination of the brittle Fella-Sava Fault. Missing dehydration products of gypsum and the lack of annealing indicate temperatures below 100 °C during development of the shear zone. Despite of such low temperatures the shear zone clearly exhibits mylonitic flow, thus evidencing laterally coeval activity of brittle and viscous deformation. The dominant structures within the gypsum rocks of the Lower Bellerophon Formation are a steeply to gently S-dipping foliation, a subhorizontal stretching lineation and pure shear-dominated porphyroclast systems. A subordinate simple shear component with dextral displacement is indicated by scattered σ-clasts. Both meso- and microscale structures are characteristic of a subsimple shear type of deformation with components of both coaxial and non-coaxial strain. Shortening in a transpressive regime was accommodated by right-lateral displacement and internal pure shear deformation within the Comeglians-Paularo shear zone. The shear zone shows evidence for a combination of two stretching faults, where stretching occurred in the rheologically weaker gypsum member and brittle behavior in enveloping lithologies.

Constraining the origin of the Messinian gypsum deposits using coupled measurement of δ^{18}O$/δD in gypsum hydration water and salinity of fluid inclusions

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Evans, Nicholas P.; Gázquez, Fernando; McKenzie, Judith A.; Chapman, Hazel J.; Hodell, David A.

2016-04-01

We used oxygen and hydrogen isotopes of gypsum hydration water (GHW) coupled with salinity deduced from ice melting temperatures of primary fluid inclusions in the same samples (in tandem with 87Sr/86Sr, δ34S and other isotopic measurements) to determine the composition of the mother fluids that formed the gypsum deposits of the Messinian Salinity Crisis from shallow and intermediate-depth basins. Using this method, we constrain the origin of the Messinian Primary Lower Gypsum (PLG) of the Sorbas basin (Betic foreland) and both the Upper Gypsum (UG) and the Lower Gypsum of the Sicilian basin. We then compare these results to measurements made on UG recovered from the deep Ionian and Balearic basins drilled during DSDP Leg 42A. The evolution of GHW δ18O/δD vs. salinity is controlled by mixing processes between fresh and seawater, coupled with the degree of evaporation. Evaporation and subsequent precipitation of gypsum from fluids dominated by freshwater will result in a depressed 87Sr/86Sr values and different trajectory in δ18O/δD vs. salinity space compared to fluids dominated by seawater. The slopes of these regression equations help to define the end-members from which the fluid originated. For example, salinity estimates from PLG cycle 6 in the Sorbas basin range from 18 to 51ppt, and after correction for fractionation factors, estimated δ18O and δD values of the mother water are low (-2.6 meteoric water during gypsum deposition, while 87Sr/86Sr (0.708942 fall below those expected from the evaporation of seawater alone, the slope of the regression equation is similar to that of seawater evaporation. This implies that there is a change up-section from a dominantly marine environment in cycle 2 to a greater influence of meteoric water in cycle 6. The UG from the Sicilian basin display greater δ18O/δD values (2.9 meteoric water that subsequently underwent intense evaporation. This observation concurs with the low values of 87Sr/86Sr from the same UG

Gypsum and hydrohalite dynamics in sea ice brines

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Butler, Benjamin M.; Papadimitriou, Stathys; Day, Sarah J.; Kennedy, Hilary

2017-09-01

Mineral authigenesis from their dissolved sea salt matrix is an emergent feature of sea ice brines, fuelled by dramatic equilibrium solubility changes in the large sub-zero temperature range of this cryospheric system on the surface of high latitude oceans. The multi-electrolyte composition of seawater results in the potential for several minerals to precipitate in sea ice, each affecting the in-situ geochemical properties of the sea ice brine system, the habitat of sympagic biota. The solubility of two of these minerals, gypsum (CaSO4 ·2H2O) and hydrohalite (NaCl · 2H2O), was investigated in high ionic strength multi-electrolyte solutions at below-zero temperatures to examine their dissolution-precipitation dynamics in the sea ice brine system. The gypsum dynamics in sea ice were found to be highly dependent on the solubilities of mirabilite and hydrohalite between 0.2 and - 25.0 ° C. The hydrohalite solubility between - 14.3 and - 25.0 ° C exhibits a sharp change between undersaturated and supersaturated conditions, and, thus, distinct temperature fields of precipitation and dissolution in sea ice, with saturation occurring at - 22.9 ° C. The sharp changes in hydrohalite solubility at temperatures ⩽-22.9 °C result from the formation of an ice-hydrohalite aggregate, which alters the structural properties of brine inclusions in cold sea ice. Favourable conditions for gypsum precipitation in sea ice were determined to occur in the region of hydrohalite precipitation below - 22.9 ° C and in conditions of metastable mirabilite supersaturation above - 22.9 ° C (investigated at - 7.1 and - 8.2 ° C here) but gypsum is unlikely to persist once mirabilite forms at these warmer (>-22.9 °C) temperatures. The dynamics of hydrohalite in sea ice brines based on its experimental solubility were consistent with that derived from thermodynamic modelling (FREZCHEM code) but the gypsum dynamics derived from the code were inconsistent with that indicated by its

Use of the “red gypsum” industrial waste as substitute of natural gypsum for commercial cements manufacturing

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Gázquez, M. J.

2012-06-01

Full Text Available The main objective of this research has been the valorisation of a waste from the TiO2 production process (sulphate method, called red gypsum, in the production of cements. This waste is mainly formed by di-hydrate calcium sulphate and iron hydroxides. To cover this objective it has been necessary to perform the physico-chemical characterisation of the red gypsum as well as the main components in the production of cements and of the new cements generated. Moreover, for the red gypsum, has been analyzed its radioactive content because it is generated in a NORM (Naturally Occurring Radioactive Materials industry. Finally, the most important properties of the obtained cements with different proportions of red gypsum in their composition have been studied by comparing them with the standard ones obtained in a Portland cement. Lastly, we have demonstrated that the new cements fulfil all the quality tests imposed by the European legislation.

El objetivo de esta investigación ha sido analizar la valorización de un residuo generado en el proceso de producción de dióxido de titanio (vía sulfato, denominado yeso rojo, en la producción de cementos. Dicho residuo está compuesto fundamentalmente por sulfato de calcio di-hidratado e hidróxidos de hierro. Para ello, ha sido necesaria la caracterización físico-química del yeso rojo, así como la de los otros componentes fundamentales en la fabricación de cementos y de los cementos generados con el mencionado residuo. Además, en el caso del yeso rojo, se ha analizado su contenido radiactivo al generarse éste en una industria NORM (Natural Occurring Radioactive Materials. Posteriormente, se han estudiado las propiedades más importantes de los cementos producidos con diferentes porcentajes de yeso rojo añadido, comparando estas mezclas con las propiedades de un cemento Portland comercial, comprobándose que se cumplen todas las normas Europeas de calidad exigibles.

Bacterial communities and the nitrogen cycle in the gypsum soils of Cuatro Ciénegas Basin, coahuila: a Mars analogue.

Science.gov (United States)

López-Lozano, Nguyen E; Eguiarte, Luis E; Bonilla-Rosso, Germán; García-Oliva, Felipe; Martínez-Piedragil, Celeste; Rooks, Christine; Souza, Valeria

2012-07-01

The OMEGA/Mars Express hyperspectral imager identified gypsum at several sites on Mars in 2005. These minerals constitute a direct record of past aqueous activity and are important with regard to the search of extraterrestrial life. Gale Crater was chosen as Mars Science Laboratory Curiosity's landing site because it is rich in gypsum, as are some desert soils of the Cuatro Ciénegas Basin (CCB) (Chihuahuan Desert, Mexico). The gypsum of the CCB, which is overlain by minimal carbonate deposits, was the product of magmatic activity that occurred under the Tethys Sea. To examine this Mars analogue, we retrieved gypsum-rich soil samples from two contrasting sites with different humidity in the CCB. To characterize the site, we obtained nutrient data and analyzed the genes related to the N cycle (nifH, nirS, and nirK) and the bacterial community composition by using 16S rRNA clone libraries. As expected, the soil content for almost all measured forms of carbon, nitrogen, and phosphorus were higher at the more humid site than at the drier site. What was unexpected is the presence of a rich and divergent community at both sites, with higher taxonomic diversity at the humid site and almost no taxonomic overlap. Our results suggest that the gypsum-rich soils of the CCB host a unique microbial ecosystem that includes novel microbial assemblies.

Messinian Salinity Crisis' Primary Evaporites: the shallow gypsum vs. deep dolomite formation paradox solved

Science.gov (United States)

De Lange, G. J.; Krijgsman, W.

2015-12-01

The Messinian Salinity Crisis (MSC) is a dramatic event that took place ~ 5.9 Ma ago, resulting in deposition of 1-3 km thick evaporites at the Mediterranean seafloor. A considerable, long-lasting controversy existed on the modes of their formation, including the observed shallow gypsum versus deep dolostone deposits for the early phase of MSC. The onset of MSC is marked by deposition of gypsum/sapropel-like alternations, thought to relate to arid/humid climate conditions at a precessional rhythm. Gypsum precipitation only occurred at marginal- and dolomite formation at deeper settings. A range of potential explanations was given, most of which cannot satisfactorily explain all observations. Biogeochemical processes during MSC are commonly neglected but may explain that different deposits formed in shallow vs deep environments without exceptional physical boundary conditions for each. A unifying mechanism is presented in which gypsum formation occurs at all shallow water depths but its preservation is limited to shallow sedimentary settings. In contrast, ongoing deep-basin anoxic organic matter (OM) degradation processes result in dolomite formation. Gypsum precipitation in evaporating seawater takes place at 3-7 times concentrated seawater; seawater is always oversaturated relative to dolomite but its formation is inhibited by the presence of dissolved sulphate. Thus conditions for formation of gypsum exclude those for formation of dolomite and vice versa. Another process linking the saturation states of gypsum and dolomite is that of OM degradation by sulphate reduction. In stagnant deep water, ongoing OM-degradation may result in reducing the sulphate and enhancing the dissolved carbonate content. Such low-sulphate / high carbonate conditions in MSC deepwater are. unfavorable for gypsum preservation and favorable for dolomite formation, and always coincide with anoxic, i.e. oxygen-free conditions. Including dynamic biogeochemical processes in the thusfar static

Crop Response to Gypsum Application to Subtropical Soils Under No-Till in Brazil: a Systematic Review

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Tales Tiecher

2018-02-01

Full Text Available ABSTRACT The use of gypsum to improve the root environment in tropical soils in the southeastern and central-western regions of Brazil is a widespread practice with well-established recommendation criteria. However, only recently gypsum began to be used on subtropical soils in South of Brazil, so available knowledge of its effect on crop yield is incipient and mainly for soils under no-till (NT systems. Avaiable studies span a wide range of responses, from a substantial increase to a slight reduction in crop yield. Also, the specific conditions leading to a favorable effect of gypsum application on crop yield are yet to be accurately identified. The primary objectives of this study were to examine previously reported results to assess the likelihood of a crop response to gypsum and to develop useful recommendation criteria for gypsum application to subtropical soils under NT in Brazil. For this purpose, we examined the results of a total of 73 growing seasons, reported in 20 different scientific publications that assessed grain yield as a function of gypsum rates. Four different scenarios were examined, by the occurrence or not of high subsurface acidity (viz., Al saturation >20 % and/or exchangeable Ca 3 cmolc dm-3 failed to increase crop yield, irrespective of the soil water status. Under these conditions, high gypsum rates (6-15 Mg ha−1 may even reduce grain yield, possibly by inducing K and Mg deficiency. On the other hand, applying gypsum to soils with high subsurface acidity increased yield by 16 % in corn (87 % of cases and by 19 % in winter cereals (83 % of cases, whether or not the soil was water-deficient. By contrast, soybean yield was only increased by gypsum applied in the simultaneous presence of high soil subsurface acidity and water deficiency (average increase 27 %, 100 % of cases.

Theoretical and Numerical Investigation of the Cavity Evolution in Gypsum Rock

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Li, Wei; Einstein, Herbert H.

2017-11-01

When water flows through a preexisting cylindrical tube in gypsum rock, the nonuniform dissolution alters the tube into an enlarged tapered tube. A 2-D analytical model is developed to study the transport-controlled dissolution in an enlarged tapered tube, with explicit consideration of the tapered geometry and induced radial flow. The analytical model shows that the Graetz solution can be extended to model dissolution in the tapered tube. An alternative form of the governing equations is proposed to take advantage of the invariant quantities in the Graetz solution to facilitate modeling cavity evolution in gypsum rock. A 2-D finite volume model was developed to validate the extended Graetz solution. The time evolution of the transport-controlled and the reaction-controlled dissolution models for a single tube with time-invariant flow rate are compared. This comparison shows that for time-invariant flow rate, the reaction-controlled dissolution model produces a positive feedback between the tube enlargement and dissolution, while the transport-controlled dissolution does not.

Clay stabilization by using gypsum and paddy husk ash with reference to UCT and CBR value

Science.gov (United States)

Roesyanto; Iskandar, R.; Hastuty, I. P.; Dianty, W. O.

2018-02-01

Clays that have low shear strength need to be stabilized in order to meet the technical requirements to serve as a subgrade material. One of the usual soil stabilization methods is by adding chemicals such as Portland cement, lime, and bitumen. The clay stabilization research was done by adding gypsum and paddy husk ash. The research goals were to find out the value of engineering properties of clay due to the addition of 2% gypsum and 2% - 15% paddy husk ash. The soil was classified as Clay - Low Plasticity (CL) based on USCS and was classified as A-7-6 (10) based on AASHTO classification system. The UCT value of original soil was 1.41 kg/cm2. While the CBR soaked and unsoaked values of original soil were 4.41% and 6.23% respectively. The research results showed the addition of paddy husk ash decreased the value of unconfined compressive strength as well as CBR. The stabilized soil by 2% gypsum and 0% paddy husk ash gave maximum UCT value of 1.67 kg/cm2, while the maximum value of CBR were found 6.71% for CBR soaked and 8.00% for CBR unsoaked. The addition of paddy husk ash did not alter the soil classification according to AASHTO or USCS, even degrade the engineering properties of original soil.

Effect of alginate chemical disinfection on bacterial count over gypsum cast.

Science.gov (United States)

Haralur, Satheesh B; Al-Dowah, Omir S; Gana, Naif S; Al-Hytham, Abdullah

2012-05-01

To evaluate the efficacy of sodium hypochlorite (1 : 10) and iodophor disinfectants on alginate impressions along with their effect on the survived bacterium count on the gypsum cast. Four alginate impression on each dentate patients were made, of which Group I were not washed or disinfected, Group II impressions were merely washed with water, Group III were disinfected by spraying with sodium hypochlorite (1 : 10), Group IV were disinfected with iodophor (1 : 213). Gypsum cast (type III) were made from all the impression. Impressions and gypsum cast were swabbed in mid palatal region for bacterial culture. Bacterial colony counting done after 3 days of incubation at 37℃ in blood agar media. The data obtained was analyzed by one way ANOVA test at a significant difference level of 0.05. Group I and Group II showed significantly more bacteria compared to Group III and Group IV. Bacterial colonies on the alginate impression and gypsum cast in group disinfected with Sodium hypochlorite (1 : 10) were 0.18, 0.82 respectively compared to group treated with iodophor (1 : 213). There was an increase in bacterial count on dental cast compared to source alginate impressions. Sodium hypochlorite (1 : 10) was found to be better disinfectant for alginate impression. There was an indication of increase in number of bacteria from alginate impression to making of dental cast. Additional gypsum cast disinfectant procedures need to be encouraged to completely eliminate cross infection to dental laboratory.

Assessment of Mercury in Soils, Crops, Earthworms, and Water when Soil is Treated with Gypsum

Science.gov (United States)

Flue gas desulfurization (FGD) gypsum from fossil fuel combustion has many potential uses in agriculture, but there is concern about the potential environmental effects of its elevated mercury (Hg) concentration. The wet limestone scrubbing process that removes sulfur from flue gas (and produces gyp...

[The effect of disinfectant soaking on dental gypsum model size].

Science.gov (United States)

Zhu, Cao-yun; Xu, Yun-wen; Xu, Kan

2012-12-01

To study the influence of disinfectant soaking on the dimensional stability of three kinds of dental gypsum model. Three commonly used gypsums ( type III,IV,Vtype) in clinic were used to make 24 specimens for 50 mm×15 mm×10 mm in size. One hour after release, the specimens were placed for 24 h. A digital caliper was used to measure the size of the gypsum model. Distilled water immersion was as used control, glutaraldehyde disinfectant and Metrix CaviCide disinfectant soaking were used for the experimental group. After soaking for 0.5h, the gypsum models were removed and placed for 0.5 h, 1 h, 2 h, 24 h. The size of the models was measured again using the same method. The data was analyzed with SPSS10.0 software package. The initial gypsum model length was (50.07±0.017) mm, (50.048±0.015) mm and (50.027±0.015) mm. After soaking for different times, the size of the model changed little, and the dimensions changed less than 0.01%. The results show that disinfectant soaking has no significant effect on dental model dimensions.

Incorporation of arsenic into gypsum: Relevant to arsenic removal and immobilization process in hydrometallurgical industry

Energy Technology Data Exchange (ETDEWEB)

Zhang, Danni; Yuan, Zidan [Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Shaofeng, E-mail: wangshaofeng@iae.ac.cn [Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Jia, Yongfeng, E-mail: yongfeng.jia@iae.ac.cn [Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Demopoulos, George P. [Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada)

2015-12-30

Highlights: • Quantitatively studied the incorporation of arsenic into the structure of gypsum. • Arsenic content in the solid increased with pH and initial arsenic concentration. • Calcium arsenate phase precipitated in addition to gypsum at higher pH values. • The structure of gypsum and its morphology was altered by the incorporated arsenate. • The incorporated arsenate formed sainfeldite-like local structure in gypsum. - Abstract: Gypsum precipitates as a major secondary mineral during the iron-arsenate coprecipitation process for the removal of arsenic from hydrometallurgical effluents. However, its role in the fixation of arsenic is still unknown. This work investigated the incorporation of arsenic into gypsum quantitatively during the crystallization process at various pHs and the initial arsenic concentrations. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray absorption near edge spectroscopy (XANES) and scanning electron microscopy (SEM) were employed to characterize the coprecipitated solids. The results showed that arsenate was measurably removed from solution during gypsum crystallization and the removal increased with increasing pH. At lower pH where the system was undersaturated with respect to calcium arsenate, arsenate ions were incorporated into gypsum structure, whereas at higher pH, calcium arsenate was formed and constituted the major arsenate bearing species in the precipitated solids. The findings may have important implications for arsenic speciation and stability of the hydrometallurgical solid wastes.

Uptake and speciation of uranium in synthetic gypsum (CaSO4•2H2O): Applications to radioactive mine tailings.

Science.gov (United States)

Lin, Jinru; Sun, Wei; Desmarais, Jacques; Chen, Ning; Feng, Renfei; Zhang, Patrick; Li, Dien; Lieu, Arthur; Tse, John S; Pan, Yuanming

2018-01-01

Phosphogypsum formed from the production of phosphoric acid represents by far the biggest accumulation of gypsum-rich wastes in the world and commonly contains elevated radionuclides, including uranium, as well as other heavy metals and metalloids. Therefore, billions-of-tons of phosphogypsum stockpiled worldwide not only possess serious environmental problems but also represent a potential uranium resource. Gypsum is also a major solid constituent in many other types of radioactive mine tailings, which stems from the common usage of sulfuric acid in extraction processes. Therefore, management and remediation of radioactive mine tailings as well as future beneficiation of uranium from phosphogysum all require detailed knowledge about the nature and behavior of uranium in gypsum. However, little is known about the uptake mechanism or speciation of uranium in gypsum. In this study, synthesis experiments suggest an apparent pH control on the uptake of uranium in gypsum at ambient conditions: increase in U from 16 μg/g at pH = 6.5 to 339 μg/g at pH = 9.5. Uranium L 3 -edge synchrotron X-ray absorption spectroscopic analyses of synthetic gypsum show that uranyl (UO 2 ) 2+ at the Ca site is the dominant species. The EXAFS fitting results also indicate that uranyl in synthetic gypsum occurs most likely as carbonate complexes and yields an average U-O distance ∼0.25 Å shorter than the average Ca-O distance, signifying a marked local structural distortion. Applications to phosphogypsum from the New Wales phosphoric acid plant (Florida, USA) and uranium mine tailings from the Key Lake mill (Saskatchewan, Canada) show that gypsum is an important carrier of uranium over a wide range of pH and controls the fate of this radionuclide in mine tailings. Also, development of new technologies for recovering U from phosphogypsum in the future must consider lattice-bound uranyl in gypsum. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

Science.gov (United States)

Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

2015-01-01

Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils.

Science.gov (United States)

Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

2015-06-01

Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline-alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation.

Hydrate Phase Assemblages in Blends of Ye'elimite and Gypsum with Alite and Belite

DEFF Research Database (Denmark)

Pedersen, Malene Thostrup; Skibsted, Jørgen

2016-01-01

Calcium sulpho-aluminate (CSA) cements all contain ye’elimite, either as the main phase or in intermediate amounts, while they differ in their content of accessory phases. Belite is the main phase in most CSA cements, however, alite - CSA cements have been produced. The hydrate phases formed during...... and hydration kinetics. The improved understanding of the hydrate phase assemblages as well as the hydration kinetics for the model systems will form the fundamental basis for further optimizations of blended systems including ye’elimite with the aim of maximizing the reaction degree of the main clinker phases...... hydration of CSA cements depend on the type of CSA cement and the amount of gypsum added. The hydration reactions of the main phases are by themselves well documented, whereas the simultaneous hydration of CSA cement components is not fully understood in terms of hydration products and kinetics. To further...

GRANULATION AND BRIQUETTING OF SOLID PRODUCTS FROM FLUE GAS DESULFURIZATION

Directory of Open Access Journals (Sweden)

Jan J. Hycnar

2015-11-01

Full Text Available Most flue gas desulfurization products can be characterized by significant solubility in water and dusting in dry state. These characteristics can cause a considerable pollution of air, water, and soil. Among many approaches to utilization of this waste, the process of agglomeration using granulation or briquetting has proved very effective. Using desulfurization products a new material of aggregate characteristics has been acquired, and this material is resistant to water and wind erosion as well as to the conditions of transportation and storage. The paper presents the results of industrial trials granulation and briquetting of calcium desulphurization products. The granulation of a mixture of phosphogypsum used with fly ash (in the share 1:5. The resulting granules characterized by a compressive strength of 41.6 MPa, the damping resistance of 70% and 14.2% abrasion. The granulate was used for the production of cement mix. The produced concrete mortar have a longer setting and hardening time, as compared to the traditional ash and gypsum mortar, and have a higher or comparable flexural and compressive strength during hardening. Briquetting trials made of a product called synthetic gypsum or rea-gypsum both in pure form and with the addition of 5% and 10% of the limestone dust. Briquettes have a high initial strength and resistance to abrasion. The values ​​of these parameters increased after 72 hours of seasoning. It was found that higher hardiness of briquettes with rea-gypsum was obtained with the impact of atmospheric conditions and higher resistance to elution of water-soluble components in comparison to ash briquettes.

Primary Evaporites for the Messinian Salinity Crisis: the shallow gypsum vs. deep dolomite formation paradox solved

Science.gov (United States)

De Lange, Gert J.; Krijgsman, Wout

2014-05-01

The Messinian Salinity Crisis (MSC) is a dramatic event that took place ~ 5.9 Ma ago, and resulted in the deposition of 0.3-3 km thick evaporites at the Mediterranean seafloor. A considerable and long-lasting controversy existed on the modes of their formation. During the CIESM Almeria Workshop a consensus was reached on several aspects. In addition, remaining issues to be solved were identified, such as for the observed shallow gypsum versus deep dolostone deposits for the early phase of MSC. The onset of MSC is marked by deposition of gypsum/sapropel-like alternations, thought to relate to arid/humid climate conditions. Gypsum precipitation only occurred at marginal settings, while dolomite containing rocks have been reported from deeper settings. A range of potential explanations have been reported, most of which cannot satisfactorily explain all observations. Biogeochemical processes during MSC are poorly understood and commonly neglected. These may, however, explain that different deposits formed in shallow versus deep environments without needing exceptional physical boundary conditions for each. We present here a unifying mechanism in which gypsum formation occurs at all shallow water depths but its preservation is mostly limited to shallow sedimentary settings. In contrast, ongoing anoxic organic matter (OM) degradation processes in the deep basin result in the formation of dolomite. Gypsum precipitation in evaporating seawater takes place at 3-7 times concentrated seawater; seawater is always largely oversaturated relative to dolomite but its formation is thought to be inhibited by the presence of dissolved sulphate. Thus the conditions for formation of gypsum exclude those for the formation of dolomite and vice versa. Another process that links the saturation states of gypsum and dolomite is that of OM degradation by sulphate reduction. In stagnant deep water, oxygen is rapidly depleted through OM degradation, then sulphate becomes the main oxidant for OM

Elementary characterization of samples of Portland cement, natural gypsum and phosphogypsum mortars from Brazil

Energy Technology Data Exchange (ETDEWEB)

Narloch, Danielle Cristine; Paschuk, Sergei Anatolyevich; Corrêa, Janine Nicolosi; Torres, Catarina Alzira Peddis; Mazer, Wellington; Macioski, Gustavo [Universidade Tecnologica Federal do Parana (UTFPR), PR (Brazil); Lara, Alessandro [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Fisica; Casali, Juliana Machado, E-mail: janine_nicolosi@hotmail.com, E-mail: alellara@hotmail.com, E-mail: jucasali@gmail.com [Instituto Federal de Santa Catarina (IFSC), Florianópolis, SC (Brazil)

2017-07-01

Portland cement, the basic ingredient of concrete and is manufactured by crushing, milling and proportioning limestone, sand, clay, iron ore and secondary materials such as shells, chalk or marl combined with shale slate or blast furnace slag, fly ash, gypsum, phosphogypsum, and some others. Evaluating the physical and mineralogical characteristics of the cement and its chemical composition is essential to establish the quality of the product. Therefore, the objective of this work was to characterize and quantify the most common chemical elements in the samples of Brazilian Portland cement, natural gypsum, and phosphogypsum mortars by means of X-ray dispersive energy spectroscopy (EDXRF), as well as to evaluate the strength of these mortars. For analysis of the compressive strength, initially prepared samples were submitted to a destructive mechanical test. Subsequently samples were milled and compacted to form thin tablets, which were submitted to the EDXRF analysis. The qualitative and quantitative analyzes showed that for phosphogypsum mortar the largest mass fractions were found of 49.8±2.5% (Si), 24.66±0.96% (S) and 22.10±0.42% (Ca). For gypsum mortar those values were found of 43.41±0.45% (Ca), 33.8 ± 0.8% (S) and 18.9±1.2% (Si), respectively; and for Portland cement mortar, the predominant elements in those samples have the mass fractions of 64.20±0.52% (Ca) and 27.3±1.5% (Si). The results showed that obtained values of mass fraction of the elements Si, S, K, Ca, Ti, Fe are in rather good agreement with quantities indicated for manufacture. Besides, gypsum and phosphogypsum presented almost the same composition and compressive strength. (author)

Elementary characterization of samples of Portland cement, natural gypsum and phosphogypsum mortars from Brazil

International Nuclear Information System (INIS)

Narloch, Danielle Cristine; Paschuk, Sergei Anatolyevich; Corrêa, Janine Nicolosi; Torres, Catarina Alzira Peddis; Mazer, Wellington; Macioski, Gustavo; Lara, Alessandro

2017-01-01

Portland cement, the basic ingredient of concrete and is manufactured by crushing, milling and proportioning limestone, sand, clay, iron ore and secondary materials such as shells, chalk or marl combined with shale slate or blast furnace slag, fly ash, gypsum, phosphogypsum, and some others. Evaluating the physical and mineralogical characteristics of the cement and its chemical composition is essential to establish the quality of the product. Therefore, the objective of this work was to characterize and quantify the most common chemical elements in the samples of Brazilian Portland cement, natural gypsum, and phosphogypsum mortars by means of X-ray dispersive energy spectroscopy (EDXRF), as well as to evaluate the strength of these mortars. For analysis of the compressive strength, initially prepared samples were submitted to a destructive mechanical test. Subsequently samples were milled and compacted to form thin tablets, which were submitted to the EDXRF analysis. The qualitative and quantitative analyzes showed that for phosphogypsum mortar the largest mass fractions were found of 49.8±2.5% (Si), 24.66±0.96% (S) and 22.10±0.42% (Ca). For gypsum mortar those values were found of 43.41±0.45% (Ca), 33.8 ± 0.8% (S) and 18.9±1.2% (Si), respectively; and for Portland cement mortar, the predominant elements in those samples have the mass fractions of 64.20±0.52% (Ca) and 27.3±1.5% (Si). The results showed that obtained values of mass fraction of the elements Si, S, K, Ca, Ti, Fe are in rather good agreement with quantities indicated for manufacture. Besides, gypsum and phosphogypsum presented almost the same composition and compressive strength. (author)

Sails: a new gypsum speleothem from Naica, Chihuahua, Mexico

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Forti Paolo

2007-01-01

Full Text Available The caves of Naica (Chihuahua, Mexico are perhaps the most famous mine caves of the world due to the presence of giganticgypsum crystals. Nevertheless, very little research has been carried out on this karst area until now. A multidisciplinary investigationstarted in 2006 with the aim not only to define the genesis and the age of the Naica gypsum crystals, but also on other scientificaspects of these caves.This paper describes a completely new type of gypsum speleothem: the “sails”, observed only inside the Cueva de las Velas, one ofthe caves of the Naica system. This speleothem consists of extremely thin, elongated skeleton crystals that have grown epitaxiallyonly on the tips of the gypsum crystals pointing upward. The genesis of sails is strictly related to the environmental conditions setup inside the cave just after the artificial lowering of the groundwater by mine dewatering (less than 20 yr ago. In a few years sail speleothems will disappear entirely and therefore this study is fundamental to preserve at least the memory of them.

Impact of Leaching Conditions on Constituents Release from Flue Gas Desulfurization Gypsum (FGDG) and FGDG-Soil Mixture

Science.gov (United States)

The interest in using Flue Gas Desulfurization Gypsum(FGDG) has increased recently. This study evaluates the leaching characteristics of trace elements in "modern" FGDG (produced after fly ash removal) and FGDG-mixed soil (SF) under different environmental conditions using rece...

Application of reject of gypsum from Trindade/PE in ceramic masses formulations; Aplicacao de residuos de gipsita em formulacoes de massas ceramicas

Energy Technology Data Exchange (ETDEWEB)

Lima, Thalles Confessor de; Souza, Marcondes Mendes de; Almeida, Ana Beatriz Dantas de; Farias, Debora Santos Umbelino de; Nobrega, Luiz Felipe Pereira de Medeiros, E-mail: thallesconfessor@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Rio Grande do Norte (IFRN), Mossoro, RN (Brazil); Mendes, Luciana Bezerra [Fundacao de Apoio a Pesquisa do Rio Grande do Norte (FAPERN), Natal RN (Brazil)

2016-07-01

The mining industry is a major producer of waste is to be harmful to the environment besides not being made possible for use in producing means, since the product of economic interest has been extracted. In order to reduce this problem, this work shows the characterization of the waste generated by gypsum mining in Trindade/PE in the ceramic coating. The residue was collected, ground and sieved to #200, then was chemically characterized by XRF analysis process, to evaluate its potential to be incorporated into the formulation of ceramic material, the material studied can be used in porcelain tile formulation as a flux element for that were obtained in the laboratory ceramic bodies adding the residue then were performed physical testing of linear shrinkage, water absorption and flexural breaking strain technically order to evaluate the addition of this residue ceramic coating. (author)

Preparation of gypsum/polymer composites using radiation

International Nuclear Information System (INIS)

Aji, Z.

2007-05-01

Gypsum composites have been prepared with different monomers using Gamma radiation: acrylamide, butyl acrylate, butyl methacrylate, methyl methacrylate, and methyl acrylate. The conversion of polymerization was determined as a function of absorbed dose. The data show that conversion of polymerization increases by increasing the dose.(author)

Crack Coalescence in Molded Gypsum and Carrara Marble

Science.gov (United States)

Wong, N.; Einstein, H. H.

2007-12-01

This research investigates the fracturing and coalescence behavior in prismatic laboratory-molded gypsum and Carrara marble specimens, which consist of either one or two pre-existing open flaws, under uniaxial compression. The tests are monitored by a high speed video system with a frame rate up to 24,000 frames/second. It allows one to precisely observe the cracking mechanisms, in particular if shear or tensile fracturing takes place. Seven crack types and nine crack coalescence categories are identified. The flaw inclination angle, the ligament length and the bridging angle between two flaws have different extents of influence on the coalescence patterns. For coplanar flaws, as the flaw inclination angle increases, there is a general trend of variation from shear coalescence to tensile coalescence. For stepped flaws, as the bridging angle changes from negative to small positive, and further up to large positive values, the coalescence generally progresses from categories of no coalescence, indirect coalescence to direct coalescence. For direct coalescence, it generally progresses from shear, mixed shear-tensile to tensile as the bridging angle increases. Some differences in fracturing and coalescence processes are observed in gypsum and marble, particularly the crack initiation in marble is preceded by the development of macroscopic white patches, but not in gypsum. Scanning Electron Microprobe (SEM) study reveals that the white patches consist of zones of microcracks (process zones).

Technical economical study of plaster production in a continuous rotate kiln using natural gas; Estudo tecnico-economico do processo de producao de gesso em forno rotativo continuo com uso de gas natural

Energy Technology Data Exchange (ETDEWEB)

Benachour, M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Santos, Valdemir A. dos [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil); Peres, Luciano dos S. [Instituto de Tecnologia de Pernambuco (ITEP), Recife, PE (Brazil); Campos, Michel F. [PETROBRAS, Rio de Janeiro, RJ (Brazil); Zimmerle, Sergio R.T.S. [Companhia Pernambucana de Gas - COPERGAS, Recife, PE (Brazil)

2004-07-01

At Araripe Gypsum Site, Pernambuco State, gypsum is dehydrated to produce plaster using wood and BPF oil as major fuels, which generate serious environmental impacts. Natural gas provides important advantages over conventional fuels. Using this gas improves the thermal efficiency of direct contact process, producing no contamination in final product, also reducing considerably environmental pollution levels. In this scope, a rotate kiln was designed in pilot scale, where was carried out gypsum dehydration tests to produce beta plaster using natural gas. In this work are presented mathematical models to simulate the axial profiles of the gypsum conversion and the gas and solid temperatures on the axial length of the kiln. The mathematical models are used as restrictions to obtention of the operational optimized conditions to a minimum gypsum conversion of the 85%. The simulation results were compared to experimental ones and were obtained a good agreement between both the values. (author)

Reclamation of acid, toxic coal spoils using wet flue gas desulfurization by-product, fly ash and sewage sludge. Final report

Energy Technology Data Exchange (ETDEWEB)

Kost, D.A.; Vimmerstedt, J.P.; Stehouwer, R.C.

1997-03-01

Establishment of vegetation on acid abandoned minelands requires modification of soil physical and chemical conditions. Covering the acid minesoil with topsoil or borrow soil is a common practice but this method may be restricted by availability of borrow soil and cause damage to the borrow site. An alternative approach is to use waste materials as soil amendments. There is a long history of using sewage sludge and fly ash as amendments for acid minesoils. Flue gas desulfurization (FGD) by-products are newer materials that are also promising amendments. Most flue gas sludges are mixtures of Calcium sulfate (CaSO{sub 4}), calcium sulfite (CaSO{sub 3}), calcium carbonate (CaCO{sub 3}), calcium hydroxide [Ca(OH){sub 2}], and fly ash. Some scrubbing processes produce almost pure gypsum (CaSO{sub 4}2H{sub 2}O). The primary purpose of the project is to evaluate two wet FGD by-products for effects on vegetation establishment and surface and ground water quality on an acid minesoil. One by-product from the Conesville, OH power plant (American Electric Power Service Corporation) contains primarily calcium sulfite and fly ash. The other by-product (Mg-gypsum FGD) from an experimental scrubber at the Zimmer power plant (Cincinnati Gas and Electric Company) is primarily gypsum with 4% magnesium hydroxide. These materials were compared with borrow soil and sewage sludge as minesoil amendments. Combinations of each FGD sludge with sewage sludge were also tested. This report summarizes two years of measurements of chemical composition of runoff water, ground water at two depths in the subsoil, soil chemical properties, elemental composition and yield of herbaceous ground cover, and elemental composition, survival and height of trees planted on plots treated with the various amendments. The borrow soil is the control for comparison with the other treatments.

Reclamation of acid, toxic coal spoils using wet flue gas desulfurization by-product, fly ash and sewage sludge. Final report

International Nuclear Information System (INIS)

Kost, D.A.; Vimmerstedt, J.P.; Stehouwer, R.C.

1997-03-01

Establishment of vegetation on acid abandoned minelands requires modification of soil physical and chemical conditions. Covering the acid minesoil with topsoil or borrow soil is a common practice but this method may be restricted by availability of borrow soil and cause damage to the borrow site. An alternative approach is to use waste materials as soil amendments. There is a long history of using sewage sludge and fly ash as amendments for acid minesoils. Flue gas desulfurization (FGD) by-products are newer materials that are also promising amendments. Most flue gas sludges are mixtures of Calcium sulfate (CaSO 4 ), calcium sulfite (CaSO 3 ), calcium carbonate (CaCO 3 ), calcium hydroxide [Ca(OH) 2 ], and fly ash. Some scrubbing processes produce almost pure gypsum (CaSO 4 2H 2 O). The primary purpose of the project is to evaluate two wet FGD by-products for effects on vegetation establishment and surface and ground water quality on an acid minesoil. One by-product from the Conesville, OH power plant (American Electric Power Service Corporation) contains primarily calcium sulfite and fly ash. The other by-product (Mg-gypsum FGD) from an experimental scrubber at the Zimmer power plant (Cincinnati Gas and Electric Company) is primarily gypsum with 4% magnesium hydroxide. These materials were compared with borrow soil and sewage sludge as minesoil amendments. Combinations of each FGD sludge with sewage sludge were also tested. This report summarizes two years of measurements of chemical composition of runoff water, ground water at two depths in the subsoil, soil chemical properties, elemental composition and yield of herbaceous ground cover, and elemental composition, survival and height of trees planted on plots treated with the various amendments. The borrow soil is the control for comparison with the other treatments

Attenuation characteristics of gypsum wallboard

International Nuclear Information System (INIS)

Christensen, Ralph C.; Sayeg, Joseph

1978-01-01

Increased cost of lead is promoting enhanced usage of common building materials for shielding in diagnostic medical and dental facilities where only a few half value layers (HVLs) are needed. We have measured attenuation of x-rays in gypsum wallboard as a function of kVp, filtration, and wallboard thickness. Our findings, obtained using a Victoreen 555 with an 0.1 DAS probe in poor geometry, are in agreement with the sparse data in the literature (Gross and McCullough (1977), Radiology 122: 825. Moos et al. (1961), Oral Surgery, Oral Medicine, and Oral Pathology 14: 569) but extend to thicker wall configurations and different kVp and filtration parameters. We conclude that gypsum wallboard as sole shielding material should be used with great caution. These findings are of value in maximizing the benefit/cost ratio for diagnostic shielding, and strengthen the conviction that, where used for shielding purposes, common building materials must be installed carefully and HVL-depth dependence considered thoroughly. (author)

Effect of disinfection on irreversible hydrocolloid and alternative impression materials and the resultant gypsum casts.

Science.gov (United States)

Suprono, Montry S; Kattadiyil, Mathew T; Goodacre, Charles J; Winer, Myron S

2012-10-01

Many new products have been introduced and marketed as alternatives to traditional irreversible hydrocolloid materials. These alternative materials have the same structural formula as addition reaction silicone, also known as vinyl polysiloxane (VPS), impression materials. Currently, there is limited in vitro and in vivo research on these products, including on the effects of chemical disinfectants on the materials. The purpose of this study was to compare the effects of a spray disinfecting technique on a traditional irreversible hydrocolloid and 3 new alternative impression materials in vitro. The tests were performed in accordance with the American National Standards Institute/American Dental Association (ANSI/ADA) Specification Nos. 18 and 19. Under standardized conditions, 100 impressions were made of a ruled test block with an irreversible hydrocolloid and 3 alternative impression materials. Nondisinfected irreversible hydrocolloid was used as the control. The impressions were examined for surface detail reproduction before and after disinfection with a chloramine-T product. Type III and Type V dental stone casts were evaluated for linear dimensional change and gypsum compatibility. Comparisons of linear dimensional change were analyzed with 2-way ANOVA of mean ranks with the Scheffé post hoc comparisons (α=.05). Data for surface detail reproduction were analyzed with the Wilcoxon Signed-Rank procedure and gypsum compatibility with the Kruskal-Wallis Rank procedure (α=.05). The alternative impression materials demonstrated significantly better outcomes with all 3 parameters tested. Disinfection with chloroamine-T did not have any effect on the 3 alternative impression materials. The irreversible hydrocolloid groups produced the most variability in the measurements of linear dimensional change. All of the tested materials were within the ADA's acceptable limit of 1.0% for linear dimensional change, except for the disinfected irreversible hydrocolloid

Gypsum-permineralized microfossils and their relevance to the search for life on Mars.

Science.gov (United States)

Schopf, J William; Farmer, Jack D; Foster, Ian S; Kudryavtsev, Anatoliy B; Gallardo, Victor A; Espinoza, Carola

2012-07-01

Orbital and in situ analyses establish that aerially extensive deposits of evaporitic sulfates, including gypsum, are present on the surface of Mars. Although comparable gypsiferous sediments on Earth have been largely ignored by paleontologists, we here report the finding of diverse fossil microscopic organisms permineralized in bottom-nucleated gypsums of seven deposits: two from the Permian (∼260 Ma) of New Mexico, USA; one from the Miocene (∼6 Ma) of Italy; and four from Recent lacustrine and saltern deposits of Australia, Mexico, and Peru. In addition to presenting the first report of the widespread occurrence of microscopic fossils in bottom-nucleated primary gypsum, we show the striking morphological similarity of the majority of the benthic filamentous fossils of these units to the microorganisms of a modern sulfuretum biocoenose. Based on such similarity, in morphology as well as habitat, these findings suggest that anaerobic sulfur-metabolizing microbial assemblages have changed relatively little over hundreds of millions of years. Their discovery as fossilized components of the seven gypsiferous units reported suggests that primary bottom-nucleated gypsum represents a promising target in the search for evidence of past life on Mars. Key Words: Confocal laser scanning microscopy-Gypsum fossils-Mars sample return missions-Raman spectroscopy-Sample Analysis at Mars (SAM) instrument-Sulfuretum.

Mechanical, Hygric and Thermal Properties of Flue Gas Desulfurization Gypsum

Directory of Open Access Journals (Sweden)

P. Tesárek

2004-01-01

Full Text Available The reference measurements of basic mechanical, thermal and hygric parameters of hardened flue gas desulfurization gypsum are carried out. Moisture diffusivity, water vapor diffusion coefficient, thermal conductivity, volumetric heat capacity and linear thermal expansion coefficient are determined with the primary aim of comparison with data obtained for various types of modified gypsum in the future. 

Potential use of gypsum and lime rich industrial by-products for induced reduction of Pb, Zn and Ni leachability in an acid soil

International Nuclear Information System (INIS)

Rodriguez-Jorda, M.P.; Garrido, F.; Garcia-Gonzalez, M.T.

2010-01-01

This study evaluates the potential use of four industrial by-products (phosphogypsum (PG), red gypsum (RG), sugar foam (SF), and ashes from biomass combustion (ACB)), applied at two rates in single and combined amendments to reduce the mobility and availability of Pb, Zn and Ni in a metal-spiked acid soil. Leaching experiments were done to estimate leachability indexes and assess their effectiveness. Most of the treatments significantly reduced the metal leachability although only a few were effective for all metals. Based on principal component and cluster analysis, sugar foam (SF) and a mixture of RG and ACB (RG+ACB), both applied at high rate, were selected as first choices to reduce mobility and availability of the three metals. Metal sorption mechanisms involved in the reduction of their leachability were identified using scanning electron microscopy. In the SF-treated samples, the metals were found associated to amorphous Al-hydroxy polymers deposited on phyllosilicates and organic matter particles. In the (RG+ACB)-treated samples, Pb, Zn, and traces of Ni were found associated to Fe/Ti oxide phases with a significant concentration of S, suggesting the formation of metal-sulfate ternary complexes.

Determination of boron content and isotopic composition in gypsum by inductively coupled plasma optical emission spectroscopy and positive thermal ionization mass spectrometry using phase transformation.

Science.gov (United States)

Ma, Yun-Qi; Peng, Zhang-Kuang; Yang, Jian; Xiao, Ying-Kai; Zhang, Yan-Ling

2017-12-01

As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate (CaCO 3 ) with ammonium bicarbonate(NH 4 HCO 3 ) by two steps at 50°C. In every step, the mass ratio of NH 4 HCO 3 /CaSO 4 ·2H 2 O was twice, and conversion rate reached more than 98%. Converted CaCO 3 was totally dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS). The boron isotopic composition of gypsum may be an excellent indicator for the formation environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Authigenic gypsum in a deep sea core from Southeastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Guptha, M.V.S.

Authigenic gypsum has been encountered in a deep sea core RC9-157 from the southeastern Arabian Sea at a depth of 4111 m which is a zone of lysocline. The formation of gypsum in the deep sea region is attributed to the prevailing sulphate rich...

Effect of amino acids on the precipitation kinetics and Ca isotopic composition of gypsum

Science.gov (United States)

Harouaka, Khadouja; Kubicki, James D.; Fantle, Matthew S.

2017-12-01

Stirred gypsum (CaSO4 · 2H2O) precipitation experiments (initial Ωgypsum = 2.4 ± 0.14, duration ≈ 1.0-1.5 h) were conducted in the presence of the amino acids glycine (190 μM), L-alanine (190 μM), D- and L-arginine (45 μM), and L-tyrosine (200 μM) to investigate the effect of simple organic compounds on both the precipitation kinetics and Ca isotopic composition of gypsum. Relative to abiotic controls, glycine, tyrosine, and alanine inhibited precipitation rates by ∼22%, 27%, and 29%, respectively, while L- and D-arginine accelerated crystal growth by ∼8% and 48%, respectively. With the exception of tyrosine, amino acid induced inhibition resulted in fractionation factors (αs-f) associated with precipitation that were no more than 0.3‰ lower than amino acid-free controls. In contrast, the tyrosine and D- and L-arginine experiments had αs-f values associated with precipitation that were similar to the controls. Our experimental results indicate that Ca isotopic fractionation associated with gypsum precipitation is impacted by growth inhibition in the presence of amino acids. Specifically, we propose that the surface-specific binding of amino acids to gypsum can change the equilibrium fractionation factor of the bulk mineral. We investigate the hypothesis that amino acids can influence the growth of gypsum at specific crystal faces via adsorption and that different faces have distinct fractionation factors (αface-fluid). Accordingly, preferential sorption of amino acids at particular faces changes the relative, face-specific mass fluxes of Ca during growth, which influences the bulk isotopic composition of the mineral. Density functional theory (DFT) calculations suggest that the energetic favorability of glycine sorption onto gypsum crystal faces occurs in the order: (1 1 0) > (0 1 0) > (1 2 0) > (0 1 1), while glycine sorption onto the (-1 1 1) face was found to be energetically unfavorable. Face-specific fractionation factors constrained by

Influence of shelf life on the setting time of type IV gypsum

Science.gov (United States)

Hapsari, M. L.; Irawan, B.; Damiyanti, M.

2017-08-01

Although expired materials can exhibit a deterioration in their properties, expired type IV gypsum can still be found on the market. In order to evaluate the influence of the shelf life on its setting time, two groups of type IV gypsum (GC Fuji rock EP) with different expiration dates were used in this research. The setting time tests were done in a mold using a Vicat Needle apparatus. The results of the statistical analysis showed a significant difference (pshelf life did influence the setting time of the type IV gypsum.

Ultrasonically nebulised electrolysed oxidising water: a promising new infection control programme for impressions, metals and gypsum casts used in dental hospitals.

Science.gov (United States)

Wu, G; Yu, X; Gu, Z

2008-04-01

Controlling the transmission of infectious diseases by impressions, metals and dental casts in dental hospitals remains a challenge. Current disinfection methods have various drawbacks. This study introduced and provided a preliminary evaluation of the feasibility of using ultrasonically nebulised, electrolysed oxidising water (UNEOW) as a new infection control programme. UNEOW was produced from freshly generated electrolysed oxidising water (EOW). Samples of impressions, titanium and gypsum were subjected to the following treatments: (1) immersion in 1% sodium hypochlorite for 10min; (2) immersion in EOW for 10min; (3) exposure to UNEOW for 15, 30 and 45min; (4) no disinfection (control). Bactericidal efficacy was examined using Staphylococcus aureus and Bacillus subtilis var. niger spores as indicators. Dimensional accuracy, surface quality, and effect of corrosion were also evaluated for the different samples. Results showed that except for B. subtilis var. niger spores on gypsum casts, the bacterial reduction log(10) values after 30-45min treatment with UNEOW were all above 4. The impression dimensional changes showed no difference between control and UNEOW groups, but both were significantly lower than the EOW and sodium hypochlorite groups (Pimpressions and gypsum casts. No assessable corrosion was found on the titanium surface after a 45min treatment with UNEOW. The findings indicated that use of UNEOW is a feasible and promising approach for controlling the transmission of infectious diseases by impressions, gypsum casts and denture metals in dental facilities.

Morphology and stability of aggregates of an Oxisol according to tillage system and gypsum application

Directory of Open Access Journals (Sweden)

Fábio Régis de Souza

2012-12-01

Full Text Available Morphological characterization and aggregate stability is an important factor in evaluating management systems. The aim of this paper is to evaluate the stability and morphology of the aggregates of a dystrophic Oxisol managed with no-tillage and conventional tillage with and without the residual action of gypsum. The experimental design was randomized blocks arranged in split-split plot, where the treatments were two soil management systems (plots with 0 and 2000 kg ha-1 of gypsum (subplots and five depths (0-0.05, 0.05-0.10, 0.10-0.15, 0.15-0.20 and 0.20-0.30 m as the subsubplots, with four replications. The aggregate morphology was determined through images and later evaluated by the Quantporo software. Stability was determined by the wet method. The results showed that the no-tillage system, with or without gypsum residual effect, provided the aggregates with the largest geometric diameters. The combination of no-tillage system and the gypsum residual effect provided rougher aggregates.

Relative Shock Effects in Mixed Powders of Calcite, Gypsum, and Quartz: A Calibration Scheme from Shock Experiments

Science.gov (United States)

Bell, Mary S.

2009-01-01

The shock behavior of calcite and gypsum is important in understanding the Cretaceous/Tertiary event and other terrestrial impacts that contain evaporite sediments in their targets. Most interest focuses on issues of devolatilization to quantify the production of CO2 or SO2 to better understand their role in generating a temporary atmosphere and its effects on climate and biota [e.g., papers in 1,2,3,4]. Devolatilization of carbonate is also important because the dispersion and fragmentation of ejecta is strongly controlled by the expansion of large volumes of gas during the impact process as well [5,6]. Shock recovery experiments for calcite yield seemingly conflicting results: early experimental devolatilization studies [7,8,9] suggested that calcite was substantially outgassed at 30 GPa (> 50%). However, the recent petrographic work of [10,11,12] presented evidence that essentially intact calcite is recovered from 60 GPa experiments. [13] reported results of shock experiments on anhydrite, gypsum, and mixtures of those phases with silica. Their observations indicate little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another (preliminary) report of shock experiments on calcite, anhydrite, and gypsum, [14] observe calcite recrystallization when shock loaded at 61 GPa, only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa. [15] shock loaded anhydrite and quartz to a peak pressure of 60 GPa. All of the quartz grains were trans-formed to glass and the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggest that recrystallization of anhydrite grains is the result of a solid state transformation. [16] reanalyzed the calcite and anhydrite shock

Corrosion of bare and galvanized steel in gypsum

Directory of Open Access Journals (Sweden)

Gómez, Mercedes

1988-12-01

Full Text Available Gypsum is a relatively low-cost building material much abounding in our country. When it is put in contact with steel, it may produce high corrosion rates due to its pH value (close to 7. This work reports the results obtained in studying the corrosion rates of bare and galvanized steel in contact with gypsum and plaster, as well as the influence curing thermal treatment applied to gypsum, enviromental relative humidity and addition of compounds with different natures and purposes may have in such process. In-situ observations, as well as the measurement of the Polarization Resistance and the weight loss have been used as measurement technics. From the results obtained it has been possible to deduce that galvanized steel has better behaviour in dry enviroments than bare steel in the same conditions and moist atmosphere induces proportionally more corrosion in galvanized steel than in bare one. Additions to gypsum do not modified these conclusions, though it may be pointed out that addition of nitrites or lime improves the behaviour of bare steel, while galvanized behaviour is not modified. The addition of lime is not recommended because phenomena of dilated along time expansion may take place.

El yeso es un material de construcción de relativo bajo coste y que, además, es muy abundante en nuestro país. Debido a su pH cercano a la neutralidad, cuando entra en contacto con el acero, este puede corroerse a elevadas velocidades. En esta comunicación se presentan los resultados de un estudio sobre la velocidad de corrosión del acero desnudo y galvanizado en contacto con yeso y escayola y la influencia que tienen: el tratamiento térmico del curado del yeso, la humedad relativa ambiental y la adición de aditivos de diversa naturaleza y finalidad. Como técnicas de medida se han utilizado la medida de la Resistencia de Polarización y de la pérdida de peso, así como observaciones visuales. De los resultados se puede deducir que en

Constructive applications of composite gypsum reinforced with Typha Latifolia fibres

Directory of Open Access Journals (Sweden)

Garcia Santos, A.

2004-03-01

Full Text Available The present research analyses the possibility to reinforce gypsum using enea fibres (Typha Latifolia creating a compound material in wich the fibres contribute to increase mechanical resistance, producing as well a reduction of the weight and a possible regulation of the set time.

La investigación presente analiza la posibilidad de reforzar los morteros de escayola mediante la utilización dé fibras de Typha Latifolia, creando un material compuesto en el que las fibras contribuyen al aumento de resistencia mecánica, a la vez que se produce una reducción del peso y una regulación de los tiempos de fraguado. Las propiedades de estos materiales hacen que, en determinadas aplicaciones, su utilización resulte ventajosa con respecto a materiales tradicionales.

Effect of gypsum, pressmud, fulvic acid and zinc sources on yield and zinc uptake by rice crop in a saline-sodic soil

International Nuclear Information System (INIS)

Chand, M.

1980-01-01

The application of fulvic acid to a saline-sodic soil augmented the solubility of zinc by thousands fold. Zinc fulvate when applied at levels equivalent to that of zinc sulphate was more effective in enhancing diffusion of zinc in the soil. Application of gypsum, zinc sulphate and fulvic acid significantly increased dry matter yield and uptake of zinc by rice crop in a saline-sodic soil. Application of gypsum with pressmud or with fulvic acid and zinc sulphate resulted in significantly higher yield and zinc uptake than in other treatments. (orig.)

Thermal conductivity of gypsum plasterboards : at ambient temperature and exposed to fire

NARCIS (Netherlands)

Korte, de A.C.J.; Brouwers, H.J.H.; Wald, F.; Kallerova, P.; Chlouba, J.

2009-01-01

One of the more complicated thermal properties to calculate for gypsum plasterboard is the thermal conductivity. The thermal conductivity is important because it plays an important role in the fire behaviour of gypsum plasterboards. Plasterboard often protects steel structures of buildings, because

76 FR 24025 - Information Collection; Prohibition on Acquisition of Products Produced by Forced or Indentured...

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2011-04-29

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Design of Cold-Formed Steel Screw Connections with Gypsum Sheathing at Ambient and Elevated Temperatures

Directory of Open Access Journals (Sweden)

Wei Chen

2016-09-01

Full Text Available Load-bearing cold-formed steel (CFS walls sheathed with double layers of gypsum plasterboard on both sides have demonstrated good fire resistance and attracted increasing interest for use in mid-rise CFS structures. As the main connection method, screw connections between CFS and gypsum sheathing play an important role in both the structural design and fire resistance of this wall system. However, studies on the mechanical behavior of screw connections with double-layer gypsum sheathing are still limited. In this study, 200 monotonic tests of screw connections with single- or double-layer gypsum sheathing at both ambient and elevated temperatures were conducted. The failure of screw connections with double-layer gypsum sheathing in shear was different from that of single-layer gypsum sheathing connections at ambient temperature, and it could be described as the breaking of the loaded sheathing edge combined with significant screw tilting and the loaded sheathing edge flexing fracture. However, the screw tilting and flexing fracture of the loaded sheathing edge gradually disappear at elevated temperatures. In addition, the influence of the loaded edge distance, double-layer sheathing and elevated temperatures is discussed in detail with clear conclusions. A unified design formula for the shear strength of screw connections with gypsum sheathing is proposed for ambient and elevated temperatures with adequate accuracy. A simplified load–displacement model with the post-peak branch is developed to evaluate the load–displacement response of screw connections with gypsum sheathing at ambient and elevated temperatures.

Thermal Dehydration Kinetics of Gypsum and Borogypsum under Non-isothermal Conditions

Institute of Scientific and Technical Information of China (English)

I.Y.Elbeyli; S.Piskin

2004-01-01

Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal conditions in air by using simultaneous thermogravimetric-differential thermal analyzer. Nonisothermal experiments were carried out at various linear heating rates. Kinetics of dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger and Doyle Equations. Values of the activation energy and the pre-exponential factor of the dehydration were calculated. The results of thermal experiments and kinetic parameters indicated that borogypsum is similar to gypsum from dehydration mechanism point of view although it consists of boron and small amount of alkali metal oxides.

PPF-reinforced, ESP-lightened gypsum plaster

Directory of Open Access Journals (Sweden)

García Santos, A.

2009-03-01

Full Text Available A new construction material has been obtained by adding aggregate to gypsum plaster which, without reducing the bending strength of plain gypsum plaster without aggregates, lowers its density, and consequently the weight of the construction elements made from the agglomerated material, by half.The aggregates used were expanded polystyrene beads and short polypropylene fibre.The new material addresses one of the issues of cardinal interest in construction materials and construction element research, namely the need to lighten materials so as to ease the burden on buildings’ bearing structures while facilitating assembly of construction units, by a single worker wherever possible.With a water / binder ratio of 0.7 and 2% (by weight of plaster of expanded polystyrene and 2% of polypropylene fibre aggregates, the decline in density achieved was 50,88% over plain gypsum plaster and 32.88% over plasterboard.Se ha obtenido un nuevo material de construcción aditivando el yeso o la escayola, mediante la incorporación de agregados, de modo que sin reducir la resistencia a flexotracción de una escayola sin ningún tipo de adición, reduce su densidad a la mitad, y por tanto, el peso de los elementos constructivos que puedan realizarse basándose en él.El material está compuesto por una adición de gránulos de poliestireno expandido y fibras cortadas de polipropileno.El nuevo material incide sobre aquellos aspectos de más interés en el campo de la investigación en construcción, en donde se intenta reducir el peso de los materiales, de modo que se grave lo menos posible la estructura resistente de las edificaciones, a la par que se facilitan los procedimientos de montaje de las unidades constructivas, al poder ser manejadas por un solo operario.La escayola, con relación de agua/conglomerante de 0,7, y con adiciones del 2% en peso (sobre la cantidad de escayola, tanto de poliestireno expandido como de fibras de polipropileno, permite reducir la

Soil fertility, nutrition and yield of maize and barley with gypsum application on soil surface in no-till

Directory of Open Access Journals (Sweden)

Leandro Michalovicz

2014-10-01

Full Text Available Annual crop yield and nutrition have shown differentiated responses to modifications in soil chemical properties brought about by gypsum application. The aim of this study was to evaluate the effect of gypsum application rates on the chemical properties of a Latossolo Bruno (Clayey Oxisol, as well as on the nutrition and yield of a maize-barley succession under no-till. The experiment was set up in November 2009 in Guarapuava, Parana, Brazil, applying gypsum rates of 0.0, 1.5, 3.0, 4.5, and 6.0 Mg ha-1 to the soil surface upon sowing maize, with crop succession of barley. Gypsum application decreased the levels of Al3+ and Mg2+ in the 0.0-0.1 m layer and increased soil pH in the layers from 0.2-0.6 m depth. Gypsum application has increased the levels of Ca2+ in all soil layers up to 0.6 m, and the levels of S-SO4(2- up to 0.8 m. In both crops, the leaf concentrations of Ca and S were increased while Mg concentrations have decreased as a function of gypsum rates. There was also an effect of gypsum rates on grain yield, with a quadratic response of maize and a linear increase for barley. Yield increases were up to 11 and 12 % in relation to control for the maximum technical efficiency (MTE rates of 3.8 and 6.0 Mg ha-1 of gypsum, respectively. Gypsum application improved soil fertility in the profile, especially in the subsurface, as well as plant nutrition, increasing the yields of maize and barley.

Polymeric-SiO2-PCMs for improving the thermal properties of gypsum applied in energy efficient buildings

International Nuclear Information System (INIS)

Borreguero, Ana M.; Serrano, Angel; Garrido, Ignacio; Rodríguez, Juan F.; Carmona, Manuel

2014-01-01

Highlights: • Inorganic–organic PCM microcapsules were incorporated into gypsum. • The physical and thermal properties of the gypsum composites were studied. • The gypsum composites presented better properties than some previously investigated. • 10.20 kW h/operating cycle could be saved in a room with 1 m 3 of this material. • 1.26 kg of CO 2 emissions could be reduced per one operating cycle. - Abstract: A new thermoregulating material containing the commercial paraffin Rubitherm®RT27 stabilized by SiO 2 with a polymeric shell from polystyrene–divinylbenzene (Polymeric-SiO 2 -PCMs) was incorporated into gypsum up to a 15 mass ratio respect to the initial hemihydrate in order to develop building materials with a high thermal energy store (TES) capacity. The effect of this material on the gypsum crystals and the main physical, thermal and mechanical properties were studied and compared to those caused by another three kinds of thermoregulating materials. Polymeric-SiO 2 -PCMs presented the lowest agglomeration and therefore, the best distribution into the gypsum pores. As expected, the thermoregulating effect of the PCM improved the thermal properties of the gypsum since, the higher the microcapsules content, the higher the equivalent heat capacity (c p ) and the accumulated heat power (q acc ). Considering a conversion of 100% of the accumulated heat into electricity savings, the addition of a 15% of microcapsules respect to the hemihydrate allowed to save 10.20 kW h/m 3 and, consequently, reduced the CO 2 emissions in a 1.26 kg of CO 2 per operating cycle. Besides, the addition of the Polymeric-SiO 2 -PCMs reduces the gypsum density, but it is always higher than 600 kg/m 3 , as required by the European regulation EN 13279-2. The thermal conductivity (k) is also reduced by the microcapsules addition but for the case of a content of 15%. On the other hand, the porosity is barely affected just varying always less than a 3.5%. Finally, despite of the

Achievement report for fiscal 2000 on development of technology to recycle disintegrated waste gypsum boards; 1999 nendo kaitai haisekko board no saishigenka gijutsu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Investigations and researches have been made on disintegrated waste gypsum boards generated in building demolishing sites, with a target of recycling them as a raw material for boards. In the investigations, the actual status of discarding the disintegrated gypsum boards was identified, whereas the harmful substance contents such as of heavy metals were verified to be below the environmental criteria. As a method to remove impurities and foreign materials from the disintegrated waste gypsum boards, the hydration crushing method was established, in which volumetric change when hemihydrate gypsum returns to gypsum dehydrate is utilized, and bond of gypsum particles with each other and with impurities is destructed to separate them into simple substances. Furthermore, discussions were given on the reforming conditions to reform in an energy saving manner the disintegrated waste gypsum boards into high-quality large-size hemihydrate gypsum by using the wet-type process that utilizes the reversible reaction between hemihydrate gypsum and gypsum dehydrate in the disintegrated waste gypsum boards. A manufacturing process to put the recycled gypsum into practical use was also discussed. Prototype board fabrication and tests were performed by using the reformed gypsum board materials, wherein good results were obtained from all of the practical, chemical, and physical tests. (NEDO)

Reforestation and landscape reconstruction in gypsum mine area from the semiarid region of NE Brazil

Science.gov (United States)

Bittar, S. M. B.; Straaten, P. V.; de Araujo Vieura Santos, M. de Fatima; Agra Bezerra da Silva, Y. J.; da Silva, M.; Saraiva de Melo Pinheiro, T.; Gusmao Didier de Moraes, F.; de Aguiar Accioly, A. M.; Alves de Santana, S. R.; dos Santos, H. A.; de Carvalho, D. M.; de Lima Ferreira, G.; de Carvalho Santos, C.

2012-04-01

In the Araripe region, Northeast Brazil, exist the world's second largest reserve of gypsum, estimated at over than one billion tons, which accounts for 95% of the Brazilian production and constitutes an important segment of the regional economy. The gypsum deposit occurs in the Lower Cretaceous Santana Formation of the Araripe basin, which is constituted by siltstones, marls, limestones, shales and gypsum layers. The ore extraction is from an open pit, on simple benches with a height of about 15 meters. Activities in mining operations involve stripping, drilling, loading explosives, blast, fragmentation and block loading / transport. Currently, gypsum mining and processing results in major changes in the landscape (pits and wastes heaps sedimentary rocks and soil mixture), deforestation of the "caatinga" ecosystem for use as firewood in small calcinations, dust pollution and changes in hydrology. To promote environmental remediation of this area, a multidisciplinary research has being done with the aim to support reforestation at the wastes heaps. The study involved the following activities: collection and physical, chemical and mineralogical characterization of mine waste materials; a floristic survey around the mines (botanical identification and measuring physical parameters in 16 plots, in order to identify which species are best suited to the conditions of the substrate at the mine site); an experiment (randomized block design) developed in a greenhouse, where seedlings of various native tree species were grown in a "constructed soil" made up of gypsum waste combined with chicken, goat and cattle manure, aimed to select tree species and soil treatment to be used in a waste heap; and an assessment of water quality for irrigation of the reforestation areas. The waste materials consist of large clayey aggregates, which may present physical/chemical properties unfavorable for plant development. The mineralogy of the sand fraction (> 85% quartz, gypsum and

Crystallisation of Gypsum and Prevention of Foaming in Wet Flue Gas Desulphurisation (FGD) Plants

DEFF Research Database (Denmark)

Hansen, Brian Brun

The aim of this project is to investigate two operational problems, which have been experienced during wet flue gas desulphurisation (FGD) operation, i.e. poor gypsum dewatering properties and foaming. The results of this work can be used for the optimization of wet FGD-plants in terms of reliabi......The aim of this project is to investigate two operational problems, which have been experienced during wet flue gas desulphurisation (FGD) operation, i.e. poor gypsum dewatering properties and foaming. The results of this work can be used for the optimization of wet FGD-plants in terms....... Experiments in a falling film wet FGD pilot plant have shown a strong non-linear behaviour (in a ln(n(l)) vs. l plot) at the lower end of the particle size range, compared to the well-known linear “mixed suspension mixed product removal (MSMPR)” model. A transient population balance model, fitted...

Production and Characterization of Bacteriocin Produced by Lactobacillus Viridescence(NICM 2167

Directory of Open Access Journals (Sweden)

Sure KP

Full Text Available The present study focused on the production optimization of bacteriocin by Lactobacillus viridescence NICM 2167 followed by its purification and characterization. The bacteriocins are antimicrobial peptides produced by many Gram positive and Gram negative bacteria.The bacteriocin produced by LAB (lactic acid bacteria received attention in recent years due to their potential application as natural preservatives in food. Bacteriocinproduced by Lactobacillus viridescence showed broad range of antimicrobial activity against food borne pathogens. Production parameters were optimized showing highest production of bacteriocinin MRS broth with pH= 7.0 incubated at 37°C for 48 h. Bacteriocin was purified in two steps involving ammonium sulphate precipitation followed by gel filtration using Sephadex G-100. Purified bacteriocin with single band on SDS-PAGE showed molecular weight of 8.3 kDa. This purified bacteriocin was stable over wide range of pH (4-10 as well as temperatures (4°C-121°C suggesting it as a potent candidate for preservation of various foods.

Production of a calcium silicate cement material from alginate impression material.

Science.gov (United States)

Washizawa, Norimasa; Narusawa, Hideaki; Tamaki, Yukimichi; Miyazaki, Takashi

2012-01-01

The purpose of this study was to synthesize biomaterials from daily dental waste. Since alginate impression material contains silica and calcium salts, we aimed to synthesize calcium silicate cement from alginate impression material. Gypsum-based investment material was also investigated as control. X-ray diffraction analyses revealed that although firing the set gypsum-based and modified investment materials at 1,200°C produced calcium silicates, firing the set alginate impression material did not. However, we succeeded when firing the set blend of pre-fired set alginate impression material and gypsum at 1,200°C. SEM observations of the powder revealed that the featured porous structures of diatomite as an alginate impression material component appeared useful for synthesizing calcium silicates. Experimentally fabricated calcium silicate powder was successfully mixed with phosphoric acid solution and set by depositing the brushite. Therefore, we conclude that the production of calcium silicate cement material is possible from waste alginate impression material.

Light in the darkening on Naica gypsum crystals

Energy Technology Data Exchange (ETDEWEB)

Castillo-Sandoval, I.; Fuentes-Cobas, L. E.; Esparza-Ponce, H. E.; Carreno-Márquez, J.; Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Miguel de Cervantes 120, Chihuahua, Chih 31109, México (Mexico); Fuentes-Montero, M. E. [Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Campus Universitario#2, Circuito Universitario, C.P.31125, Chihuahua, Chih. México (Mexico); Reyes-Cortes, M. [Facultad de Ingeniería. Universidad Autónoma de Chihuahua, Campus Universitario#2, Circuito Universitario, C.P.31125, Chihuahua, Chih. México (Mexico)

2015-07-23

Naica mine is located in a semi-desertic region at the central-south of Chihuahua State. The Cave of Swords was discovered in 1910 and the Cave of Crystals 90 years later at Naica mines. It is expected that during the last century the human presence has changed the microclimatic conditions inside the cave, resulting in the deterioration of the crystals and the deposition of impurities on gypsum surfaces. As a contribution to the clarification of the mentioned issues, the present work refers to the use of synchrotron radiation for the identification of phases on these surfaces. All the experiments were performed at the Stanford Synchrotron Radiation Lightsource. Grazing incidence X-ray diffraction (GIXRD) and radiography-aided X-ray diffraction (RAXRD) experiments were performed at beamline 11-3. X-Ray micro-fluorescence (μ-SXRF) and micro-X-ray absorption (μ-XANES) were measured at beamline 2-3. Representative results obtained may be summarized as follows: a) Gypsum, galena, sphalerite, hematite and cuprite at the surface of the gypsum crystals were determined. b) The samples micro-structure is affected by impurities. c) The elemental distributions and correlations (0.6-0.9) of Cu, K, Fe, Mn, Pb, Zn, Ca and S were identified by μ-SXRF. The correlations among elemental contents confirmed the phase identification, with the exception of manganese and potassium due to the amorphous nature of some impurity compounds in these samples. The compounds hematite (Fe{sub 2}O{sub 3}), β-MnO{sub 2}, Mn{sub 2}O{sub 3}, MnO and/or MnCO{sub 3}, PbS, PbCO{sub 3} and/or PbSO4, ZnO{sub 4}, ZnS and/or smithsonite (ZnCO{sub 3}), CuS + Cu Oxide were identified by XANES. Plausibly, these latter compounds do not form crystalline phases.

Light in the darkening on Naica gypsum crystals

International Nuclear Information System (INIS)

Castillo-Sandoval, I.; Fuentes-Cobas, L. E.; Esparza-Ponce, H. E.; Carreno-Márquez, J.; Montero-Cabrera, M. E.; Fuentes-Montero, M. E.; Reyes-Cortes, M.

2015-01-01

Naica mine is located in a semi-desertic region at the central-south of Chihuahua State. The Cave of Swords was discovered in 1910 and the Cave of Crystals 90 years later at Naica mines. It is expected that during the last century the human presence has changed the microclimatic conditions inside the cave, resulting in the deterioration of the crystals and the deposition of impurities on gypsum surfaces. As a contribution to the clarification of the mentioned issues, the present work refers to the use of synchrotron radiation for the identification of phases on these surfaces. All the experiments were performed at the Stanford Synchrotron Radiation Lightsource. Grazing incidence X-ray diffraction (GIXRD) and radiography-aided X-ray diffraction (RAXRD) experiments were performed at beamline 11-3. X-Ray micro-fluorescence (μ-SXRF) and micro-X-ray absorption (μ-XANES) were measured at beamline 2-3. Representative results obtained may be summarized as follows: a) Gypsum, galena, sphalerite, hematite and cuprite at the surface of the gypsum crystals were determined. b) The samples micro-structure is affected by impurities. c) The elemental distributions and correlations (0.6-0.9) of Cu, K, Fe, Mn, Pb, Zn, Ca and S were identified by μ-SXRF. The correlations among elemental contents confirmed the phase identification, with the exception of manganese and potassium due to the amorphous nature of some impurity compounds in these samples. The compounds hematite (Fe 2 O 3 ), β-MnO 2 , Mn 2 O 3 , MnO and/or MnCO 3 , PbS, PbCO 3 and/or PbSO4, ZnO 4 , ZnS and/or smithsonite (ZnCO 3 ), CuS + Cu Oxide were identified by XANES. Plausibly, these latter compounds do not form crystalline phases

The solidification of low level radioactive organic fluids with Envirostone Gypsum Cement

International Nuclear Information System (INIS)

Rosenstiel, T.L.; Lange, R.G.

1984-01-01

The primary method for the management of low level radioactive waste (LLW) has been and continues to be the isolation of the waste in a solid mass. Of the four typical LLW streams, organic fluids pose the most significant waste isolation problem. The organic fluids comprised of lubrication oils, hydraulic fluids, sludges, scintillation fluids, etc., result from the operation and maintenance of nuclear power generating stations, research activities, tooling operations, and diagnostic analyses. The United States Gypsum Company developed the patented Envirostone Gypsum Cement system for the solidification of all types of low level radioactive wastes to facilitate handling and transportation to regulated LLW disposal sites. For the solidification of organic fluids, Envirostone Gypsum Cement is used in conjunction with Envirostone Emulsifier, selected for its ability to emulsify a broad range of organic fluids in aqueous solutions. In the solidification process it is theorized that as the crystalline matrix of the gypsum forms, the micelles of the emulsifier behave as a chemical bridge which draws the organic fluid into the crystalline structure via the hydration water. Initial testing of physical properties of solidified waste forms, including leachability, per the requirements and the procedures specified for 10 CFR Part 61 as outlined in the Branch Technical Position Report from the United States Nuclear Regulatory Commission were in progress as of the writing of this paper. Upon completion of this testing a Topical Report will be submitted to the USNRC for review and approval. The presentation reviews field experience in the use of Envirostone Gypsum Cement for the solidification of low level radioactive organic fluids from nuclear power generating stations and makes an economic comparison between Envirostone Gypsum Cement and portland cement systems

Competition between reaction-induced expansion and creep compaction during gypsum formation: Experimental and numerical investigation

Science.gov (United States)

Skarbek, R. M.; Savage, H. M.; Spiegelman, M. W.; Kelemen, P. B.; Yancopoulos, D.

2017-12-01

Deformation and cracking caused by reaction-driven volume increase is an important process in many geological settings, however the conditions controlling these processes are poorly understood. The interaction of rocks with reactive fluids can change permeability and reactive surface area, leading to a large variety of feedbacks. Gypsum is an ideal material to study these processes. It forms rapidly at room temperature via bassanite hydration, and is commonly used as an analogue for rocks in high-temperature, high-pressure conditions. We conducted uniaxial strain experiments to study the effects of applied axial load on deformation and fluid flow during the formation of gypsum from bassanite. While hydration of bassanite to gypsum involves a solid volume increase, gypsum exhibits significant creep compaction when in contact with water. These two volume changing processes occur simultaneously during fluid flow through bassanite. We cold-pressed bassanite powder to form cylinders 2.5 cm in height and 1.2 cm in diameter. Samples were compressed with a static axial load of 0.01 to 4 MPa. Water infiltrated initially unsaturated samples through the bottom face and the height of the samples was recorded as a measure of the total volume change. We also performed experiments on pure gypsum samples to constrain the amount of creep observed in tests on bassanite hydration. At axial loads 1 MPa, creep in the gypsum dominates and samples exhibit monotonic compaction. At intermediate loads, samples exhibit alternating phases of compaction and expansion due to the interplay of the two volume changing processes. We observed a change from net compaction to net expansion at an axial load of 0.250 MPa. We explain this behavior with a simple model that predicts the strain evolution, but does not take fluid flow into account. We also implement a 1D poro-visco-elastic model of the imbibition process that includes the reaction and gypsum creep. We use the results of these models, with

Accuracy of Gypsum Casts after Different Impression Techniques and Double Pouring.

Directory of Open Access Journals (Sweden)

Stephania Caroline Rodolfo Silva

Full Text Available This study evaluated the accuracy of gypsum casts after different impression techniques and double pouring. Ten patients were selected and for each one it was obtained 5 partial putty/wash impressions with vinyl polysiloxane (VPS material from teeth #13 to #16 with partial metal stock trays. The following techniques were performed: (1 one-step; two-step relief with: (2 PVC film; (3 slow-speed tungsten carbide bur and scalpel blade, (4 small movements of the tray and (5 without relief-negative control. The impressions were disinfected with 0.5% sodium hypochlorite for 10 minutes and stored during 110 and 230 minutes for the first and second pouring, respectively, with type IV gypsum. Three intra-oral lateral photographs of each patient were taken using a tripod and a customized radiographic positioner. The images were imported into ImageJ software and the total area of the buccal surface from teeth #13 to #16 was measured. A 4.0% coefficient of variance was criterion for using these measurements as Baseline values. The casts were photographed and analyzed using the same standardization for the clinical images. The area (mm2 obtained from the difference between the measurements of each gypsum cast and the Baseline value of the respective patient were calculated and analyzed by repeated-measures two way-ANOVA and Mauchly's Sphericity test (α = 0.05. No significant effect was observed for Impression technique (P = 0.23, Second pouring (P = 0.99 and their interaction (P = 0.25. The impression techniques and double pouring did not influence the accuracy of the gypsum casts.

76 FR 42709 - Submission for OMB Review; Prohibition on Acquisition of Products Produced by Forced or...

Science.gov (United States)

2011-07-19

... on Acquisition of Products Produced by Forced or Indentured Child Labor AGENCY: Department of Defense... acquisition of products produced by forced or indentured child labor. DATES: Submit comments on or before... on Acquisition of Products Produced by Forced or Indentured Child Labor, by any of the following...

Analysis of failure of voice production by a sound-producing voice prosthesis

NARCIS (Netherlands)

van der Torn, M.; van Gogh, C.D.L.; Verdonck-de Leeuw, I M; Festen, J.M.; Mahieu, H.F.

OBJECTIVE: To analyse the cause of failing voice production by a sound-producing voice prosthesis (SPVP). METHODS: The functioning of a prototype SPVP is described in a female laryngectomee before and after its sound-producing mechanism was impeded by tracheal phlegm. This assessment included:

Biological sulfate removal from gypsum contaminated construction and demolition debris.

Science.gov (United States)

Kijjanapanich, Pimluck; Annachhatre, Ajit P; Esposito, Giovanni; van Hullebusch, Eric D; Lens, Piet N L

2013-12-15

Construction and demolition debris (CDD) contains high levels of sulfate that can cause detrimental environmental impacts when disposed without adequate treatment. In landfills, sulfate can be converted to hydrogen sulfide under anaerobic conditions. CDD can thus cause health impacts or odor problems to landfill employees and surrounding residents. Reduction of the sulfate content of CDD is an option to overcome these problems. This study aimed at developing a biological sulfate removal system to reduce the sulfate content of gypsum contaminated CDD in order to decrease the amount of solid waste, to improve the quality of CDD waste for recycling purposes and to recover sulfur from CDD. The treatment leached out the gypsum contained in CDD by water in a leaching column. The sulfate loaded leachate was then treated in a biological sulfate reducing Upflow Anaerobic Sludge Blanket (UASB) reactor to convert the sulfate to sulfide. The UASB reactor was operated at 23 ± 3 °C with a hydraulic retention time and upflow velocity of 15.5 h and 0.1 m h(-1), respectively while ethanol was added as electron donor at a final organic loading rate of 3.46 g COD L(-1) reactor d(-1). The CDD leachate had a pH of 8-9 and sulfate dissolution rates of 526.4 and 609.8 mg L(-1) d(-1) were achieved in CDD gypsum and CDD sand, respectively. Besides, it was observed that the gypsum dissolution was the rate limiting step for the biological treatment of CDD. The sulfate removal efficiency of the system stabilized at around 85%, enabling the reuse of the UASB effluent for the leaching step, proving the versatility of the bioreactor for practical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface controlled dissolution rates of gypsum in aqueous solutions exhibit nonlinear dissolution kinetics

Science.gov (United States)

Jeschke, Alexander A.; Vosbeck, Katrin; Dreybrodt, Wolfgang

2001-01-01

The effective dissolution rates of gypsum are determined by mixed kinetics, where the rate constants of dissolution at the surface and the transport constant of molecular diffusion of dissolved material are similar. To obtain the surface reaction rate law it is necessary to know the transport constant. We have determined the surface rate law for monocrystalline selenite by using a rotating disc set-up, where the transport coefficients are well known. As a result, up to a calcium concentration of 0.6 · ceq, we find a nearly linear rate law Rs = ksl (1- cs/ ceq) n1, where cs is the total calcium concentration at the surface and ceq the equilibrium concentration with respect to gypsum, n1 = 1.2 ± 0.2, and ksl = 1.1 · 10 -4 mmol cm -2 s -1 ± 15%. We also employed batch-experiments for selenite, alabaster and gypsum rock samples. The result of these experiments were interpreted by using a transport constant determined by NaCl dissolution experiments under similar physical conditions. The batch experiments reveal a dissolution rate law Rs = ksl (1- cs/ ceq) n1, ksl = 1.3 · 10 -4 mmol · cm -2 s -1, n1 = 1.2 ± 0.2 for c ≤ 0.94 · ceq. Close to equilibrium a nonlinear rate law, Rs = ks2 (1- cs/ ceq) n2, is observed, where ks2 is in the order of 10 mmol · cm -2 s -1 and n2 ≈ 4.5. The experimentally observed gypsum dissolution rates from the batch experiments could be accurately fitted, with only minor variations of the surface reaction constant obtained from the rotating disk experiment and the transport coefficient from the NaCl dissolution batch experiment. Batch experiments on pure synthetic gypsum, reveal a linear rate law up to equilibrium. This indicates inhibition of dissolution in natural samples close to equilibrium, as is known also for calcite minerals.

Investigation of the gypsum quality at three full-scale wet flue gas desulphurisation plants

DEFF Research Database (Denmark)

Hansen, Brian Brun; Kiil, Søren; Johnsson, Jan Erik

2011-01-01

In the present study the gypsum (CaSO4·2H2O) quality at three full-scale wet flue gas desulphurisation (FGD) plants and a pilot plant were examined and compared. Gypsum quality can be expressed in terms of moisture content (particle size and morphology dependent) and the concentration of residual......, low moisture content and low impurity content). An episode concerning a sudden deterioration in the gypsum dewatering properties was furthermore investigated, and a change in crystal morphology, as well as an increased impurity content (aluminium, iron and fluoride), was detected....

Visible and Mid-Infrared Gypsum Optical Constants for Modeling of Martian Deposits

Science.gov (United States)

Roush, Ted L.; Esposito, Francesca; Rossmann, George R.; Colangeli, Luigi

2007-08-01

Introduction: Recent and on-going remote and in situ observations indicate that sulfates are present in significant abundances at various locations on Mars [1-7]. The Mars Reconnaissance Orbiter (MRO) imaging spectrometer (CRISM) is returning hyperspectral data at higher spatial resolution [8] than the OMEGA instrument on the Mars Express Mission [3]. Data from both OMEGA and CRISM have provided spectral evidence for the presence of gypsum and various hydrated sulfates on the Martian surface [e.g. 3-7] Thus, the optical properties of sulfates, in general, are of interest to quantitative interpretation of this increasing volume of remotely sensed data. This is because optical constants describe how a material interacts with electromagnetic radiation and represent the fundamental values used in radiative transfer calculations describing a variety of physical environments. Such environments include atmospheres where aerosols are present, planetary and satellite regoliths, and circumstellar dust clouds. Here we focus upon gypsum because of its applicability due to its identification on Mars. Also, gypsum is a mineral that is readily available in samples sizes that are suitable for study using a variety of spectral measurements. In the infrared (>5 μm) several studies reporting the optical constants of gypsum can be used in evaluating the approach used here. Most importantly, there is a general lack of data regarding the optical constants for gypsum at visible and mid-infrared wavelengths (0.4-5 μm) that are being observed by OMEGA and CRISM. Background: In the infrared, there have been several studies focused at determining the optical constants of gypsum using classical dispersion models [9-11]. These have used a variety of samples including; crystals, compressed pellets of pure materials, and grains suspended in a KBr matrix. Spectral measurements of gypsum, and other sulfates, have existed for about 100 years at visible and mid-infrared wavelengths (0.4-5 μm) [e

Implications of moisture content determination in the environmental characterisation of FGD gypsum for its disposal in landfills

Energy Technology Data Exchange (ETDEWEB)

Alvarez-Ayuso, E. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris s/n, 08028 Barcelona (Spain)], E-mail: ealvarez@ija.csic.es; Querol, X. [Department of Environmental Geology, Institute of Earth Sciences ' Jaume Almera' (CSIC), C/ Lluis Sole i Sabaris s/n, 08028 Barcelona (Spain); Tomas, A. [Endesa Generacion, S.A., C/ Ribera de Loira 60, 28042 Madrid (Spain)

2008-05-01

The leachable contents of elements of environmental concern considered in the Council Decision 2003/33/EC on waste disposal were determined in flue gas desulphurisation (FGD) gypsum. To this end, leaching tests were performed following the standard EN-12457-4 which specifies the determination of the dry mass of the material at 105 deg. C and the use of a liquid to solid (L/S) ratio of 10 l kg{sup -1} dry matter. Additionally, leaching tests were also carried out taking into account the dry mass of the material at 60 deg. C and using different L/S ratios (2, 5, 8, 10, 15 and 20 l kg{sup -1} dry matter). It was found that the dry mass determination at 105 deg. C turns out to be inappropriate for FGD gypsum since at this temperature gypsum transforms into bassanite, and so, in addition to moisture content, crystalline water is removed. As a consequence the moisture content is overvalued (about 16%), what makes consider a lower L/S ratio than that specified by the standard EN-12457-4. As a result the leachable contents in FGD gypsum are, in general, overestimated, what could lead to more strict environmental requirements for FGD gypsum when considering its disposal in landfills, specially concerning those elements (e.g., F) risking the characterisation of FGD gypsum as a waste acceptable at landfills for non-hazardous wastes.

Recovery of drinking water and by-products from gold mine effluents via alkali-bariumcalcium processing

CSIR Research Space (South Africa)

Wilsenach, J

2008-11-01

Full Text Available , after which the produced sludge was removed, and a fresh batch of BaCO3 dosed. Sludges (metal hydroxides, gypsum/Mg(OH)2 and BaSO4/CaCO3) were collected and treated in batch operation for dewatering, drying and reduction in a kiln..., potassium and chloride can be treated via conventional reverse osmosis following the chemical desalination as pretreatment to remove all scale forming substances, such as metals, calcium and sulphate. Sulphate removal as gypsum Sulphate...

Physical, chemical and radioactive characterization of co-products from titanium dioxide industry for valorization in the cement industry

International Nuclear Information System (INIS)

Gazquez, M.J.; Mantero, J.; Bolivar, J.P.; Garcia-Tenorio, R.; Vaca, F.

2011-01-01

The present study was conducted to characterize the raw materials (ilmenite and slag), waste (red gypsum) and several co-products (sulphate monohydrate and sulphate heptahydrated) form the titanium dioxide industry in relation to their elemental composition (major, minor and trace elements), granulometry, mineralogy, microscopic morphology, physical composition and radioactive content in order to apply this knowledge in the valorization of the co-products in the fields such a as construction, civil engineering, etc. In particular, the main properties of cements produced with different proportions of red gypsum were studied, and the obtained improvements, in relation to Ordinary Portland Cements (OPC) were evaluated. It was also demonstrated that the levels of pollutants and the radioactive content in the produced RG cements, remain within the regulated safety limits. (Author). 38 refs.

Investigation on the Permeability Evolution of Gypsum Interlayer Under High Temperature and Triaxial Pressure

Science.gov (United States)

Tao, Meng; Yechao, You; Jie, Chen; Yaoqing, Hu

2017-08-01

The permeability of the surrounding rock is a critical parameter for the designing and assessment of radioactive waste disposal repositories in the rock salt. Generally, in the locations that are chosen for radioactive waste storage, the bedded rock salt is a sedimentary rock that contains NaCl and Na2SO4. Most likely, there are also layers of gypsum ( {CaSO}_{ 4} \\cdot 2 {H}_{ 2} {O)} present in the salt deposit. Radioactive wastes emit a large amount of heat and hydrogen during the process of disposal, which may result in thermal damage of the surrounding rocks and cause a great change in their permeability and tightness. Therefore, it is necessary to investigate the permeability evolution of the gypsum interlayer under high temperature and high pressure in order to evaluate the tightness and security of the nuclear waste repositories in bedded rock salt. In this study, a self-designed rock triaxial testing system by which high temperature and pressure can be applied is used; the μCT225kVFCB micro-CT system is also employed to investigate the permeability and microstructure of gypsum specimens under a constant hydrostatic pressure of 25 MPa, an increasing temperature (ranging from 20 to 650 °C), and a variable inlet gas pressure (1, 2, 4, 6 MPa). The experimental results show: (a) the maximum permeability measured during the whole experiment is less than 10-17 m2, which indicates that the gypsum interlayer has low permeability under high temperature and pressure that meet the requirements for radioactive waste repository. (b) Under the same temperature, the permeability of the gypsum specimen decreases at the beginning and then increases as the pore pressure elevates. When the inlet gas pressure is between 0 and 2 MPa, the Klinkenberg effect is very pronounced. Then, as the pore pressure increases, the movement behavior of gas molecules gradually changes from free motion to forced directional motion. So the role of free movement of gas molecules gradually

Why does carbon increase in highly weathered soil under no-till upon lime and gypsum use?

Science.gov (United States)

Inagaki, Thiago Massao; de Moraes Sá, João Carlos; Caires, Eduardo Fávero; Gonçalves, Daniel Ruiz Potma

2017-12-01

Field experiments have been used to explain how soil organic carbon (SOC) dynamics is affected by lime and gypsum applications, however, how SOC storage occurs is still debatable. We hypothesized that although many studies conclude that Ca-based soil amendments such as lime and gypsum may lead to SOC depletion due to the enhancement of microbial activity, the same does not occur under conservation agriculture conditions. Thus, the objective of this study was to elucidate the effects of lime and gypsum applications on soil microbial activity and SOC stocks in a no-till field and in a laboratory incubation study simulating no-till conditions. The field experiment was established in 1998 in a clayey Oxisol in southern Brazil following a completely randomized blocks design with a split-plot arrangement and three replications. Lime and gypsum were surface applied in 1998 and reapplied in 2013. Undisturbed soil samples were collected before the treatments reapplications, and one year after. The incubation experiment was carried out during 16months using these samples adding crop residues on the soil surface to simulate no-till field conditions. Lime and gypsum applications significantly increased the labile SOC stocks, microbial activity and soil fertility attributes in both field and laboratory experiments. Although the microbial activity was increased, no depletion of SOC stocks was observed in both experiments. Positive correlations were observed between microbial activity increase and SOC gains. Labile SOC and Ca 2+ content increase leads to forming complex with mineral soil fractions. Gypsum applications performed a higher influence on labile SOC pools in the field than in the laboratory experiment, which may be related to the presence of active root system in the soil profile. We conclude that incubation experiments using lime and gypsum in undisturbed samples confirm that soil microbial activity increase does not deplete SOC stocks under conservation agriculture

Influence of gypsum and farmyard manure on fertilizer zinc uptake by wheat and its residual effect on succeeding rice and wheat crops in a sodic soil

International Nuclear Information System (INIS)

Sachdev, P.; Deb, D.L.

1990-01-01

Greenhouse experiments were conducted to evaluate the effectiveness of gypsum and FYM on a sodic soil on fertilizer Zn uptake by wheat and residual effect on succeeding crops of rice and wheat. Application of FYM significantly increased the yield of first wheat crop as well as the yield of subsequent rice and wheat crops, but gypsum showed significant effect only on rice. FYM application also resulted in an increase in Zn content of all the three crops. Utilisation of the fertilizer Zn by the first crop of wheat ranged between 0.30 to 0.54 per cent while succeeding crop of rice utilised 1.00 to 1.25 per cent of the applied Zn. Application of gypsum to the first crop did not influence the fertilizer Zn uptake by wheat, rice and wheat, however, it significantly reduced the soil pH and increased the available Zn content in soil. (author). 15 refs., 6 tabs

Preliminary Estimate of Gypsum Deposit Based on Wenner

African Journals Online (AJOL)

Dogara M. D. and Aloa J. O.

estimating the quantity of some possible deposits of gypsum. Just ... exploitation is an everyday activity that is currently going on, but, on a 'wild cat' ... important source of wealth for a nation, but before they are harnessed ..... REFERENCES.

Process for fabrication of dry flue gas gypsum. Verfahren zur Herstellung von trockenem Rauchgasgips

Energy Technology Data Exchange (ETDEWEB)

Wirsching, F.; Hueller, R.; Limmer, B.

1984-06-20

According to the invention gypsum from flue gas wet desulfurization is dried without loss of crystallization water by a 1-4% sidestream of the flue gas in a suspended bed dryer and is subsequently separated in a cyclone. The sidestream is removed after the electrostatic precipitator, where the gas temperature is 100-130 degrees, and returned to the main gas stream prior to desulfurization, thus preventing the dehydration of the gypsum and eliminating the energy costs of reheating the gas stream to prevent acid condensation.

Composite Gypsum Binders with Silica-containing Additives

Science.gov (United States)

Chernysheva, N. V.; Lesovik, V. S.; Drebezgova, M. Yu; Shatalova, S. V.; Alaskhanov, A. H.

2018-03-01

New types of fine mineral additives are proposed for designing water-resistant Composite Gypsum Binders (CGB); these additives significantly differ from traditional quartz feed: wastes from wet magnetic separation of Banded Iron Formation (BIF WMS waste), nanodispersed silica powder (NSP), chalk. Possibility of their combined use has been studied as well.

Mechanical properties of simulated Mars materials: gypsum-rich sandstones and lapilli tuff

Science.gov (United States)

Morrow, Carolyn; Lockner, David; Okubo, Chris

2013-01-01

Observations by the Mars Exploration Rover (MER) Opportunity, and other recent studies on diagenesis in the extensive equatorial layered deposits on Mars, suggest that the likely lithologies of these deposits are gypsum-rich sandstones and tuffaceous sediments (for example, Murchie and others, 2009; Squyres and others, 2012; Zimbelman and Scheidt, 2012). Of particular interest is how the diagenesis history of these sediments (degree of cementation and composition) influences the strength and brittle behavior of the material. For instance, fractures are more common in lower porosity materials under strain, whereas deformation bands, characterized by distributed strain throughout a broader discontinuity in a material, are common in higher porosity sedimentary materials. Such discontinuities can either enhance or restrict fluid flow; hence, failure mode plays an important role in determining the mechanics of fluid migration through sediments (Antonellini and Aydin, 1994; 1995; Taylor and Pollard, 2000; Ogilvie and Glover, 2001). As part of a larger study to characterize processes of fault-controlled fluid flow in volcaniclastic and gypsum-rich sediments on Mars, we have completed a series of laboratory experiments to focus on how gypsum clast content and degree of authigenic cementation affects the strength behavior of simulated Mars rocks. Both axial deformation and hydrostatic pressure tests were done at room temperature under dry conditions.

An analysis of the persistent presence of opportunistic pathogens on patient-derived dental impressions and gypsum casts.

Science.gov (United States)

Egusa, Hiroshi; Watamoto, Takao; Abe, Keike; Kobayashi, Munemasa; Kaneda, Yoshitoshi; Ashida, Shunji; Matsumoto, Takuya; Yatani, Hirofumi

2008-01-01

This study aimed to assess the persistent presence of microorganisms on patient-derived dental impressions and gypsum casts, while highlighting important human pathogens such as Candida, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa. The practices and opinions regarding cross-infection control from 59 general dentists in Japan were obtained via a questionnaire. Alginate impressions were made from 56 patients. Using a brain heart infusion agar medium, impression and imprint cultures were carried out to visualize the microbial contamination on the surfaces of the impressions and gypsum casts, respectively. The colonies on the surfaces of the 30 impression cultures and 26 imprint cultures were collected by swabbing and then inoculated onto selective agar plates to detect streptococci, staphylococci, Candida, MRSA, and P aeruginosa. The questionnaire showed that only 54% of general dentists had a cross-infection policy in their dental clinics, and only 30% to 40% were aware of the possible persistence of MRSA or P aeruginosa on impressions and gypsum casts. The impression/imprint cultures grew a large number of visible bacterial colonies on all of impression/gypsum cast samples investigated. Selective agar cultures demonstrated the presence of streptococci (100, 100%), staphylococci (56.7, 65.4%), Candida (30, 46.2%), MRSA (26.7, 15.4%), and P aeruginosa (6.7, 7.7%) on the impressions and the gypsum casts, respectively. This investigation showed that patient-derived dental impressions and gypsum casts are contaminated with numerous microbes, including Candida, MRSA, and P aeruginosa, which are known pathogens responsible for nosocomial and/or life-threatening infection in the immunocompromised host.

Mineral Carbonation of Phosphogypsum Waste for Production of Useful Carbonate and Sulfate Salts

Energy Technology Data Exchange (ETDEWEB)

Mattila, Hannu-Petteri, E-mail: hmattila@abo.fi; Zevenhoven, Ron [Thermal and Flow Engineering Laboratory, Åbo Akademi University, Turku (Finland)

2015-11-16

Phosphogypsum (CaSO{sub 4}·2H{sub 2}O, PG) waste is produced in large amounts during phosphoric acid (H{sub 3}PO{sub 4}) production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred megatonnes of carbon dioxide (CO{sub 2}). For example, when gypsum is converted to ammonium sulfate [(NH{sub 4}){sub 2}SO{sub 4}] with ammonia (NH{sub 3}) and CO{sub 2}, also solid calcium carbonate (CaCO{sub 3}) is generated. The ammonium sulfate can be utilized as a fertilizer or in other mineral carbonation processes that use magnesium silicate-based rock as feedstock, while calcium carbonate has various uses as, e.g., filler material. The reaction extent of the described process was studied by thermodynamic modeling and experimentally as a function of reactant concentrations and temperature. Other essential properties such as purity and quality of the solid products are also followed. Conversion efficiencies of >95% calcium from PG to calcium carbonate are obtained. Scalenohedral, rhombohedral, and prismatic calcite particles can be produced, although the precipitates contain certain contaminants such as rare earth metals and sulfur from the gypsum. A reverse osmosis membrane cartridge is also tested as an alternative and energy-efficient method of concentrating the ammonium sulfate salt solution instead of the traditional evaporation of the process solution.

Mineral carbonation of phosphogypsum waste for production of useful carbonate and sulfate salts

Directory of Open Access Journals (Sweden)

Hannu-Petteri eMattila

2015-11-01

Full Text Available Phosphogypsum (CaSO4·2H2O waste is produced in large amounts during phosphoric acid (H3PO4 production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred Mt of carbon dioxide (CO2. For example, when gypsum is converted to ammonium sulfate ((NH42SO4 with ammonia (NH3 and CO2, also solid calcium carbonate (CaCO3 is generated. The ammonium sulfate can be utilized as a fertilizer or in other mineral carbonation processes that use magnesium silicate-based rock as feedstock, while calcium carbonate has various uses as e.g. filler material. The reaction extent of the described process was studied by thermodynamic modeling and experimentally as a function of reactant concentrations and temperature. Other essential properties such as purity and quality of the solid products are also followed. Conversion efficiencies of >95% calcium from phosphogypsum to calcium carbonate are obtained. Scalenohedral, rhombohedral and prismatic calcite particles can be produced, though the precipitates contain certain contaminants such as rare earth metals and sulfur from the gypsum. A reverse osmosis membrane cartridge is also tested as an alternative and energy-efficient method of concentrating the ammonium sulfate salt solution instead of the traditional evaporation of the process solution.

Fate of gypsum-sulphur applied to soybean on Typic haplustepts

International Nuclear Information System (INIS)

Saharan, Neelam; Rattan, R.K.

2004-01-01

Field experiments were conducted on the sulphur-deficient Typic Haplustepts of the IARI farm for two consecutive, kharif seasons viz. 1996 and 1997 with soybean cultivar Pusa 22 as the crop. Varying rates of S as gypsum were basally applied in the main plots adjacent to the micro plots (1 m x 1 m) to quantify the partitioning of the fertilizer-sulphur taken up by soybean and its distribution in the soil profile. Soybean responded to the application of sulphur, with increase in yield being obtained up to rate of 40 kg S ha -1 . Data computed on distribution of the S derived from labelled gypsum and percent S utilization by the soybean crop increased from 13.23 and 4.15 to 23.41 and 6.39, respectively. During 1996, the per cent utilization of labelled S ranged from 5.6 to 8.8. Monitoring of added sulphur in the soil profile up to a depth of 1 m revealed maximum accumulation of the added S in 30-60 cm soil layer. With the help of 35 S around 11 to 18 per cent of the added S was traced in 60-100 cm soil layer. It can be concluded from the data for two years that during kharif season the application of S through water soluble sources like ammonium sulphate and ammonium phosphate sulphate should be avoided because even S from the sparingly soluble gypsum migrated to a depth of 1 m during the cropping season. (author)

Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass

DEFF Research Database (Denmark)

Klinke, H.B.; Thomsen, A.B.; Ahring, Birgitte Kiær

2004-01-01

for ethanol fermentation. The resulting hydrolyzsates contain substances inhibitory to fermentation-depending on both the raw material (biomass) and the pre-treatment applied. An overview of the inhibitory effect on ethanol production by yeast and bacteria is presented. Apart from furans formed by sugar......An overview of the different inhibitors formed by pre-treatment of lignocellulosic materials and their inhibition of ethanol production in yeast and bacteria is given. Different high temperature physical pre-treatment methods are available to render the carbohydrates in lignocellulose accessible...... degradation, phenol monomers from lignin degradation are important co-factors in hydrolysate inhibition, and inhibitory effects of these aromatic compounds on different ethanol producing microorganisms is reviewed. The furans and phenols generally inhibited growth and ethanol production rate (Q...

Lipid and Phylogenetic Analysis of a Gypsum-hosted Endoevaporitic Microbial Community

Science.gov (United States)

Turk, K. A.; Jahnke, L. L.; Green, S. J.; Kubo, M. D.; Vogel, M. B.; Des Marais, D. J.

2007-12-01

Gypsum evaporites host diverse, productive and volumetrically significant microbial communities and are relevant modern-day analogs to both Precambrian sabkha deposits and, potentially, Martian evaporites. Extensive evaporites form in subaqueous environments of high salinity ponds (>150 permil) maintained by the Exportadora de Sal, S. A. (ESSA) in Guerrero Negro, B.C.S., Mexico. A gypsarenite (reworked clastic gypsum) crust found along the southeast margin of ESSA's Pond 9 was collected in February 2004 and each vibrantly colored layer in the top centimeter was sampled. Extant microbial communities from each layer were characterized using complementary culture-independent molecular techniques, lipid biomarker analysis, and compound specific isotopic analysis. Coupling molecular analysis with lipid biomarker analysis revealed that oxygenic photosynthetic organisms dominate the surface layers (top 3 mm). Polar lipids from the surface layers consisted predominantly of glycolipids, which are characteristic of algae, cyanobacteria and green anoxygenic photosynthetic bacteria. Consistent with prior analyses of gypsum evaporites, 16S rRNA gene clone libraries indicate that cyanobacterial populations belong primarily to the genus Cyanothece. The bacterial community below the surface layers is more diverse and dominated by anaerobic organisms. Phototrophic purple sulfur bacteria, sulfate-reducing bacteria (SRB), and Bacteroidetes were particularly abundant. The relative abundances of SRB increased with depth; Desulfobacteraceae clones were distributed throughout the crust, but not at the surface, while Desulfovibrionaceae clones were found predominantly in the deepest layers. These molecular results are consistent with fatty acid biomarker analysis. δ13C values of major lipid classes in the crust and sediment range from 14 to 36‰, which is considerably lower than corresponding values for benthic Microcoleus-dominated cyanobacterial mats found at lower salinities at ESSA

Technical Note: Historic gypsum-kilns (Morata de Tajuña, Madrid

Directory of Open Access Journals (Sweden)

Llamas Borrajo, J. F.

2007-08-01

Full Text Available In the locality of Morata de Tajuña and surroundings there was an important settlement of gypsum pits and limekilns, together with other historical industries, now disappear. These activities were developed mainly during the 1960´s and 70´s, but its production decreased because of changes in the productive processes (substitution of discontinuous processes by continuous ones, higher kilns, etc. (1. Nevertheless, some of these furnaces still remain, as well as ancient workers who have provided important information. Within the research project funded by the Madrid´s Government, entitled: Industrial archaeology: Conservation of the mining and metallurgical heritage of Madrid (IV, ancient gypsum pits have been identified and inventoried. The ancient gypsiferous extraction history was recovered and the productive processes fluxes were reconstructed. The state of the heritage is evaluated and the conservation of some of the elements is recommended. Likewise, the intangible heritage was also investigated, being able to show a legend related with these kilns.En Morata de Tajuña y pueblos limítrofes hay una importante tradición yesera y calera, así como de otras industrias de materiales de la construcción ya desaparecidas, sobre todo en los años 60-70 del pasado siglo, debido a cambios en los sistemas productivos (paso de sistemas discontinuos a continuos, hornos mayores, etc. (1. Por eso aún se conservan algunos hornos y también viven antiguos productores, a los que hemos podido preguntar sobre los procesos productivos. En el marco de un proyecto de investigación de la Consejería de Educación de la Comunidad de Madrid titulado “Arqueología Industrial: conservación del patrimonio minero-metalúrgico madrileño (IV” se están identificando e inventariando viejas yeserías, recuperando la historia yesera local, reconstruyendo los flujos productivos y entrevistando a antiguos operarios. De esta manera, se pretende evaluar

In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

Institute of Scientific and Technical Information of China (English)

LIU Chuan-Jiang; ZHENG Hai-Fei

2012-01-01

An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC).The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa.With increasing temperature,the anhydrite (CaSO4) phase precipitates at 250 320℃ in the pressure range of 1.0 1.5 GPa,indicating that under a saturated water condition,both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite.A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) =0.0068T - 0.7126 (250℃≤T≤320℃).Anhydrite remained stable during rapid cooling of the sample chamber,showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature.%An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 Mpa. With increasing temperature, the anhydrite (CaSO4) phase precipitates at 250-320℃ in the pressure range of 1.0-1.5 Gpa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(Gpa) = 0.0068T - 0.7126 (250℃≤T≤320℃). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is

Determination of Radium 226 in mexican phosphate fertilizers and gypsum by gamma spectrometry.; Determinacion de Radio 226 en fertilizantes fosfatados y en yeso mediante espectrometria gamma.

Energy Technology Data Exchange (ETDEWEB)

Godinez A, M C

1996-12-31

The {sup 226} Ra isotope was determined in 17, 20 and 46% m/m phosphate fertilizers and gypsum. The samples of the fertilizers were dissolved in 10% v/v nitric acid solutions. The barium sulphate method was used for the precipitation of {sup 226} Ra. On the other hand, alkaline fusion method was used to separate the {sup 226} Ra from gypsum. The results indicated that {sup 226} Ra was present in the phosphate fertilizers and gypsum. The {sup 226} Ra concentrations present in these materials were between 10 {sup -4} - 10 {sup -5} {mu}g g{sup -1}. (Author).

Gypsum and organic matter distribution in a mixed construction and demolition waste sorting process and their possible removal from outputs.

Science.gov (United States)

Montero, A; Tojo, Y; Matsuo, T; Matsuto, T; Yamada, M; Asakura, H; Ono, Y

2010-03-15

With insufficient source separation, construction and demolition (C&D) waste becomes a mixed material that is difficult to recycle. Treatment of mixed C&D waste generates residue that contains gypsum and organic matter and poses a risk of H(2)S formation in landfills. Therefore, removing gypsum and organic matter from the residue is vital. This study investigated the distribution of gypsum and organic matter in a sorting process. Heavy liquid separation was used to determine the density ranges in which gypsum and organic matter were most concentrated. The fine residue that was separated before shredding accounted for 27.9% of the waste mass and contained the greatest quantity of gypsum; therefore, most of the gypsum (52.4%) was distributed in this fraction. When this fine fraction was subjected to heavy liquid separation, 93% of the gypsum was concentrated in the density range of 1.59-2.28, which contained 24% of the total waste mass. Therefore, removing this density range after segregating fine particles should reduce the amount of gypsum sent to landfills. Organic matter tends to float as density increases; nevertheless, separation at 1.0 density could be more efficient. (c) 2009 Elsevier B.V. All rights reserved.

Application of gypsum as shielding against low-energy X-radiation in the radiodiagnosis area

International Nuclear Information System (INIS)

Lins, J.A.G.; Lima, F.R.A.; Santos, M.A.P. dos; Oliveira, D.N.S. de; Silva, V.H.F.F. da

2017-01-01

In recent years, materials such as lead, concrete and iron have been studied for use as shielding for ionizing radiations of different energies in radiative installations. In the radiodiagnosis area, lead and barite are the most used materials as shielding. However, for beams of low energy X-radiation, such as in mammography and dentistry, the gypsum material may be used. This study aims to verify the feasibility of the use of gypsum as shielding for low-energy X-ray using standardized dental X-ray beams in a metrology laboratory. The project will allow a better understanding in the study of gypsum used as shielding, certifying its use as a good attenuator for low-energy X-ray

Reaction mechanism of reductive decomposition of FGD gypsum with anthracite

International Nuclear Information System (INIS)

Zheng, Da; Lu, Hailin; Sun, Xiuyun; Liu, Xiaodong; Han, Weiqing; Wang, Lianjun

2013-01-01

Highlights: • The reaction mechanism was different if the molar ratio of C/CaSO 4 was different. • The yield of CaO rises with an increase in temperature. • The optimal ratio of C/CaSO 4 = 1.2:1. • The decomposition process is mainly apparent solid–solid reaction with liquid-phase involved. - Abstract: The process of decomposition reaction between flue gas desulfurization (FGD) gypsum and anthracite is complex, which depends on the reaction conditions and atmosphere. In this study, thermogravimetric analysis with Fourier transform infrared spectroscopy (TGA-FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and the experiment in a tubular reactor were used to characterize the decomposition reaction in a nitrogen atmosphere under different conditions. The reaction mechanism analysis showed that the decomposition reaction process and mechanism were different when the molar proportion of C/CaSO 4 was changed. The experiment results showed that appropriate increase in the C/CaSO 4 proportion and higher temperatures were suitable for the formation of the main production of CaO, which can help us to understand the solid state reaction mechanism better. Via kinetic analysis of the reaction between anthracite and FGD gypsum under the optimal molar ratio of C/CaSO 4 , the mechanism model of the reaction was confirmed and the decomposition process was a two-step reaction which was in accordance with apparent solid–solid reaction

Influence of Flue Gas Desulfurization Gypsum on Reducing Soluble Phosphorus in Successive Runoff Events from a Coastal Plain Bermudagrass Pasture.

Science.gov (United States)

Watts, Dexter B; Torbert, H Allen

2016-05-01

Controlling the threat that pastures intensively managed with poultry litter (PL) pose to accelerating eutrophication is a major issue in the southeastern United States. Gypsum (CaSO) has been identified as a promising management tool for ameliorating litter P losses to runoff. Thus, research was conducted to elucidate gypsum's residual effects on P losses from a bermudagrass ( L.) pasture. Runoff events (60 min) were created using rainfall simulations. Treatments consisted of applying four flue gas desulfurization (FGD) gypsum rates (0, 2.2, 4.4, and 8.9 Mg ha) to bermudagrass fertilized with 13.4 Mg ha PL plus a nonfertilized check (no litter or gypsum) and 8.9 Mg ha FGD gypsum only as controls. Rainfall simulations (∼ 85 mm h) were conducted immediately, 5 wk, and 6 mo (i.e., at the end of growing season) after PL application to determine gypsum's effectiveness at controlling P loss over successive runoff events. The greatest dissolved P (DP) in runoff occurred immediately after PL application. Gypsum effectively reduced cumulative DP concentration losses (54%) compared with PL alone in initial runoff events. Gypsum reduced DP concentrations in succeeding runoff events also regardless of timing, suggesting that its effect is persistent and will not diminish over a growing season. Generally, maximum DP reductions were achieved with 8.9 Mg ha. However, it was surmised from this study that optimal P reduction in a bermudagrass pasture can be achieved with 4.4 Mg ha. Information ascertained from this study may be useful in aiding land managers making prescriptions for management practices that reduce DP losses from agricultural fields. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

The impact of gypsum mine water: A case study on morphology and DNA integrity in the freshwater invertebrate, Gammarus balcanicus

International Nuclear Information System (INIS)

Ternjej, Ivančica; Mihaljević, Zlatko; Ivković, Marija; Previšić, Ana; Stanković, Igor; Maldini, Krešimir; Želježić, Davor; Kopjar, Nevenka

2014-01-01

The aim of our study was to investigate how exposure to heavy metal-rich waters from gypsum mining affects the morphology and levels of primary DNA damage in Gammarus balcanicus. Chemical analysis revealed increased concentrations of metals in water and sediment collected at a site impacted by gypsum mine wastewaters. The specimens also showed elevated total tissue metal levels when compared with the organisms collected at the reference site. The most prominent increase was observed for strontium, followed by iron, nickel, vanadium, aluminium, and manganese. The major pathway of entry for these toxic substances was through the degraded exoskeleton as a consequence of excessive strontium input (unbalanced calcium/strontium ratio) and altered permeability. Disturbed exoskeleton integrity was observed only in individuals collected downstream of the gypsum mine, which was confirmed by electron microscopy. Levels of primary DNA damage were evaluated using the alkaline comet assay in the haemolymph of the specimens. - Highlights: • Our findings suggest toxic potential of gypsum mine wastewaters. • The Gammarus specimens showed elevated total tissue metal levels. • Strontium uptake disturbed exoskeleton integrity. • Corrupted cuticle altered permeability to other toxic substances. • Combined effects of all contaminants caused genotoxicity. - Gypsum mine wastewaters have genotoxic potential and affect the gammarid exoskeleton morphology and biochemistry associated with a high strontium uptake

Fabrication and properties of microencapsulated-paraffin/gypsum-matrix building materials for thermal energy storage

International Nuclear Information System (INIS)

Su Junfeng; Wang Xinyu; Wang Shengbao; Zhao Yunhui; Huang Zhen

2012-01-01

Graphical abstract: DSC curves of microPCMs/gypsum composite samples before and after a thermal cycling treatment. Highlights: ► Microcapsules containing paraffin was fabricated by in-situ polymerization. ► Methanol-modified melamine–formaldehyde (MMF) was used as shell material. ► MicroPCMs/gypsum-matrix building materials were applied for solar energy storage. ► The structure and thermal conductivity of composites had been investigated. - Abstract: Microencapsulated phase change materials (microPCMs) have been widely applied in solid matrix as thermal-storage or temperature-controlling functional composites. The aim of this work was to prepare and investigate the properties of microPCMs/gypsum-matrix building materials for thermal energy storage. MicroPCMs contain paraffin was fabricated by in situ polymerization using methanol-modified melamine–formaldehyde (MMF) as shell material. A series of microPCMs samples were prepared under emulsion stirring rates in range of 1000–3000 r min −1 with core/shell weight ratios of 3/1, 2/1, 1/1, 1/2 and 1/3, respectively. The shell of microPCMs was smooth and compact with global shape, its thickness was not greatly affected by the core/shell ratio and emulsion stirring rate. DSC tests showed that the shell of microPCMs did not influence the phase change behavior of pure paraffin. It was found from TGA analysis that microPCMs samples containing paraffin lost their weight at the temperature of nearly 250 °C, which indicated that the PCM had been protected by shell. More shell material in microPCMs could enhance the thermal stability and provide higher compact condition for core material. After a 100-times thermal cycling treatment, the microPCMs contain paraffin also nearly did not change the phase change behaviors of PCM. With the increasing of weight contents of microPCMs in gypsum board, the thermal conductivity (λ) values of composites had decreased. The simulation of temperature tests proved that the

Assesment of the legislation about biocidal products produced by nanotechnology in Turkey

OpenAIRE

Terzi, Özlem; Köksal, Elif Nur

2018-01-01

The aimofthis study is to determine whether the legislations in Turkey includebiocidal products produced by nanotechnology. The data were obtained fromscientific articles and Official Gazette website. Results: In our daily life,due to their antibacterial and antifungal characteristics, nanoparticles (NP)derived from some metal and metal oxides are used in food and textile productsas protector. In addition, antimicrobial features of biocidal products becomemore effective by means of nanotechno...

Dimensional accuracy and surface property of titanium casting using gypsum-bonded alumina investment.

Science.gov (United States)

Yan, Min; Takahashi, Hidekazu; Nishimura, Fumio

2004-12-01

The aim of the present study was to evaluate the dimensional accuracy and surface property of titanium casting obtained using a gypsum-bonded alumina investment. The experimental gypsum-bonded alumina investment with 20 mass% gypsum content mixed with 2 mass% potassium sulfate was used for five cp titanium castings and three Cu-Zn alloy castings. The accuracy, surface roughness (Ra), and reaction layer thickness of these castings were investigated. The accuracy of the castings obtained from the experimental investment ranged from -0.04 to 0.23%, while surface roughness (Ra) ranged from 7.6 to 10.3microm. A reaction layer of about 150 microm thickness under the titanium casting surface was observed. These results suggested that the titanium casting obtained using the experimental investment was acceptable. Although the reaction layer was thin, surface roughness should be improved.

Estimates of the radiation dose from phospho-gypsum plaster-board if used in domestic buildings

International Nuclear Information System (INIS)

O'Brien, R.S.; Peggie, J.R.; Leith, I.S.

1991-02-01

This report presents the results of a study carried out to estimate the annual effective dose equivalent contribution from phospho-gypsum plaster-board if it were used as an internal lining in buildings. The study considered four sources of radiation exposure that would arise in such use, such as inhalation of 222 Rn and its daughters, inhalation of phospho-gypsum dust and exposure to beta and gamma radiation. Measurements of the 22 6Ra content and 222 Rn exhalation rate were made for a number of samples of phospho-gypsum plaster-board, and the behaviour of 222 Rn and its daughters in a typical building was modelled. The results of the study suggest that, for building ventilation rates greater than approximately 0.5 air changes per hour, the contribution to the total annual effective dose equivalent from inhalation of radon ( 222 Rn) and its daughters ( 218 Po, 214 Pb, 214 Po) exhaled from the phospho-gypsum plaster-board should be well below the recommended limit of 1 milli-Sievert for members of the public. The total annual effective dose equivalent from all these sources should be less than 0.6 milli-Sieverts, provided reasonable work practices are observed during installation of the phospho-gypsum plaster-board and the ventilation rate is kept above approximately 0.5 air changes per hour. 31 refs., 12 tabs., 5 figs

Land subsidence and caprock dolines caused by subsurface gypsum dissolution and the effect of subsidence on the fluvial system in the Upper Tigris Basin (between Bismil Batman, Turkey)

Science.gov (United States)

Doğan, Uğur

2005-11-01

Karstification-based land subsidence was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land subsidence, where there are secondary and tertiary subsidence developments, reaches 140 km 2. Subsidence depth ranges between 40 and 70 m. The subsidence was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a subsidence with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of subsidence and formation of caprock dolines on loosely textured Upper Miocene-Pliocene cover formations. The Tigris River runs through the subsidence area between Batman and Bismil. There are four terrace levels as T1 (40 m), T2 (30 m), T3 (10 m) and T4 (4-5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by subsidence. The subsidence developed gradually throughout the Quaternary; however no terrace was formed purely because of subsidence.

Neutron production by cosmic-ray muons in various materials

Science.gov (United States)

Manukovsky, K. V.; Ryazhskaya, O. G.; Sobolevsky, N. M.; Yudin, A. V.

2016-07-01

The results obtained by studying the background of neutrons produced by cosmic-raymuons in underground experimental facilities intended for rare-event searches and in surrounding rock are presented. The types of this rock may include granite, sedimentary rock, gypsum, and rock salt. Neutron production and transfer were simulated using the Geant4 and SHIELD transport codes. These codes were tuned via a comparison of the results of calculations with experimental data—in particular, with data of the Artemovsk research station of the Institute for Nuclear Research (INR, Moscow, Russia)—as well as via an intercomparison of results of calculations with the Geant4 and SHIELD codes. It turns out that the atomic-number dependence of the production and yield of neutrons has an irregular character and does not allow a description in terms of a universal function of the atomic number. The parameters of this dependence are different for two groups of nuclei—nuclei consisting of alpha particles and all of the remaining nuclei. Moreover, there are manifest exceptions from a power-law dependence—for example, argon. This may entail important consequences both for the existing underground experimental facilities and for those under construction. Investigation of cosmic-ray-induced neutron production in various materials is of paramount importance for the interpretation of experiments conducted at large depths under the Earth's surface.

Radiological properties of a wax-gypsum compensator material

International Nuclear Information System (INIS)

Plessis, F.C.P. du; Willemse, C.A.

2005-01-01

In this paper the radiological properties of a compensator material consisting of wax and gypsum is presented. Effective attenuation coefficients (EACs) have been determined from transmission measurements with an ion chamber in a Perspex phantom. Measurements were made at 80 and 100 cm source-to-skin distance (SSD) for beam energies of 6, 8, and 15 MV, for field sizes ranging from narrow beam geometries up to 40x40 cm 2 , and at measurement depths of maximum dose build-up, 5 and 10 cm. A parametrization equation could be constructed to predict the EAC values within 4% uncertainty as a function of field size and depth of measurement. The EAC dependence on off-axis position was also quantified at each beam energy and SSD. It was found that the compensator material reduced the required thickness for compensation by 26% at 8 MV when compared to pure paraffin wax for a 10x10 cm 2 field. Relative surface ionization (RSI) measurements have been made to quantify the effect of scattered electrons from the wax-gypsum compensator. Results indicated that for 80 cm SSD the RSI would exceed 50% for fields larger than 15x15 cm 2 . At 100 cm SSD the RSI values were below 50% for all field sizes used

Analysis of cubic and orthorhombic C3A hydration in presence of gypsum and lime

KAUST Repository

Kirchheim, A. P.; Fernà ndez-Altable, V.; Monteiro, P. J. M.; Dal Molin, D. C. C.; Casanova, I.

2009-01-01

Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to study the microstructural changes and phase development that take place during the hydration of cubic (pure) and orthorhombic (Na-doped) tricalcium aluminate (C3A) and gypsum in the absence and presence of lime. The results demonstrate that important differences occur in the hydration of each C3A polymorph and gypsum when no lime is added; orthorhombic C3A reacts faster with gypsum than the cubic phase, forming longer ettringite needles; however, the presence of lime slows down the formation of ettringite in the orthorhombic sample. Additional rheometric tests showed the possible effects on the setting time in these cementitious mixes.

Analysis of cubic and orthorhombic C3A hydration in presence of gypsum and lime

KAUST Repository

Kirchheim, A. P.

2009-02-26

Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to study the microstructural changes and phase development that take place during the hydration of cubic (pure) and orthorhombic (Na-doped) tricalcium aluminate (C3A) and gypsum in the absence and presence of lime. The results demonstrate that important differences occur in the hydration of each C3A polymorph and gypsum when no lime is added; orthorhombic C3A reacts faster with gypsum than the cubic phase, forming longer ettringite needles; however, the presence of lime slows down the formation of ettringite in the orthorhombic sample. Additional rheometric tests showed the possible effects on the setting time in these cementitious mixes.

Mercury Concentrations in Plant Tissues as Affected by FGDG Application to Soil

Science.gov (United States)

Flue Gas Desulfurization Gypsum (FGDG) is produced by reducing sulfur dioxide emissions from themo-electric coal-fired power plants. The most common practice of FGDG production may trap some of the Mercury (Hg) present in the coal that normally would escape as vapor in the stack gases. Concern for t...

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste.

Science.gov (United States)

Nasrullah, Muhammad; Vainikka, Pasi; Hannula, Janne; Hurme, Markku; Kärki, Janne

2014-11-01

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material

New blue pigment produced by Pantoea agglomerans and its production characteristics at various temperatures.

Science.gov (United States)

Fujikawa, Hiroshi; Akimoto, Ryo

2011-01-01

A bacterium capable of producing a deep blue pigment was isolated from the environment and identified as Pantoea agglomerans. The pigment production characteristics of the bacterium under various conditions were studied. The optimal agar plate ingredients for pigment production by the bacterium were first studied: the optimal ingredients were 5 g/liter glucose, 10 g/liter tryptic soy broth, and 40 g/liter glycerol at pH 6.4. Bacterial cells grew on the agar plate during the incubation, while the pigment spread into the agar plate, meaning that it is water soluble. Pigment production was affected by the initial cell density. Namely, at higher initial cell densities ranging from 10(6.3) to 10(8.2) CFU/cm(2) on the agar plate, faster pigment production was observed, but no blue pigment was produced at a very high initial density of 10(9.1) CFU/cm(2). Thus, the cell population of 10(8.2) CFU/cm(2) was used for subsequent study. Although the bacterium was capable of growing at temperatures above and below 10°C, it could produce the pigment only at temperatures of ≥10°C. Moreover, the pigment production was faster at higher temperatures in the range of 10 to 20°C. Pigment production at various temperature patterns was well described by a new logistic model. These results suggested that the bacterium could be used in the development of a microbial temperature indicator for the low-temperature-storage management of foods and clinical materials. To our knowledge, there is no other P. agglomerans strain capable of producing a blue pigment and the pigment is a new one of microbial origin.

Origin and diagenetic evolution of gypsum and microbialitic carbonates in the Late Sag of the Namibe Basin (SW Angola)

Science.gov (United States)

Laurent, Gindre-Chanu; Edoardo, Perri; Ian, Sharp R.; Peacock, D. C. P.; Roger, Swart; Ragnar, Poulsen; Hercinda, Ferreira; Vladimir, Machado

2016-08-01

Ephemeral evaporitic conditions developed within the uppermost part of the transgressive Late Sag sequence in the Namibe Basin (SW Angola), leading to the formation of extensive centimetre- to metre-thick sulphate-bearing deposits and correlative microbialitic carbonates rich in pseudomorphs after evaporite crystals. The onshore pre-salt beds examined in this study are located up to 25 m underneath the major mid-Aptian evaporitic succession, which is typified at the outcrop by gypsiferous Bambata Formation and in the subsurface by the halite-dominated Loeme Formation. Carbonate-evaporite cycles mostly occur at the top of metre-thick regressive parasequences, which progressively onlap and overstep landward the former faulted (rift) topography, or fill major pre-salt palaeo-valleys. The sulphate beds are made up of alabastrine gypsum associated with embedded botryoidal nodules, dissolution-related gypsum breccia, and are cross-cut by thin satin-spar gypsum veins. Nodular and fine-grained fabrics are interpreted as being diagenetic gypsum deposits resulting from the dissolution and recrystallisation of former depositional subaqueous sulphates, whereas gypsum veins and breccia result from telogenetic processes. The carbonates display a broader diversity of facies, characterised by rapid lateral variations along strike. Thin dolomitic and calcitic bacterial-mediated filamentous microbialitic boundstones enclose a broad variety of evaporite pseudomorphs and can pass laterally over a few metres into sulphate beds. Dissolution-related depositional breccias are also common and indicate early dissolution of former evaporite layers embedded within the microbialites. Sulphate and carbonate units are interpreted as being concomitantly deposited along a tide-dominated coastal supra- to intertidal- sabkha and constitute high-frequency hypersaline precursor events, prior to the accumulation of the giant saline mid-Aptian Bambata and Loeme Formations. Petrographic and geochemical

Cradle-to-gate environmental assessment of enzyme products produced industrially in Denmark by Novozymes A/S

DEFF Research Database (Denmark)

Nielsen, Per H.; Oxenbøll, Karen; Wenzel, Henrik

2007-01-01

of environmental impact are usually fermentation processes due to electricity and ingredient consumption. Enzyme production has been the subject of significant optimisation during the past decades by implementation of e.g. gene modified production strains, and the provided environmental data are only...... and use of hazardous chemicals. The present paper provides a methodological framework for analysing environmental impacts of enzyme products and environmental data for five characteristic enzyme products. Methods. Life cycle assessment is used as an analytical tool and modelling of enzyme production...... for five representative enzyme products produced by Novozymes in Denmark have been determined, and a basis for further assessments of more of Novozymes' enzyme products has been established. Environmental impacts induced by producing the considered enzyme products vary by a factor 10 or more depending...

The effect of magnesium on partial sulphate removal from mine water as gypsum.

Science.gov (United States)

Tolonen, Emma-Tuulia; Rämö, Jaakko; Lassi, Ulla

2015-08-15

The aim of this research was to investigate the effect of magnesium on the removal efficiency of sulphate as gypsum from mine water. The precipitation conditions were simulated with MINEQL + software and the simulation results were compared with the results from laboratory jar test experiments. Both the simulation and the laboratory results showed that magnesium in the mine water was maintaining sulphate in a soluble form as magnesium sulphate (MgSO4) at pH 9.6. Thus magnesium was preventing the removal of sulphate as gypsum (CaSO4·2H2O). However, change in the lime precipitation pH from 9.6 to 12.5 resulted in magnesium hydroxide (Mg(OH)2) precipitation and improved sulphate removal. Additionally, magnesium hydroxide could act as seed crystals for gypsum precipitation or co-precipitate sulphate further enhancing the removal of sulphate from mine water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbonate and carbon isotopic evolution of groundwater contaminated by produced water brine with hydrocarbons

International Nuclear Information System (INIS)

Atekwana, Eliot A.; Seeger, Eric J.

2015-01-01

The major ionic and dissolved inorganic carbon (DIC) concentrations and the stable carbon isotope composition of DIC (δ"1"3C_D_I_C) were measured in a freshwater aquifer contaminated by produced water brine with petroleum hydrocarbons. Our aim was to determine the effects of produced water brine contamination on the carbonate evolution of groundwater. The groundwater was characterized by three distinct anion facies: HCO_3"−-rich, SO_4"2"−-rich and Cl"−-rich. The HCO_3"−-rich groundwater is undergoing closed system carbonate evolution from soil CO_2_(_g_) and weathering of aquifer carbonates. The SO_4"2"−-rich groundwater evolves from gypsum induced dedolomitization and pyrite oxidation. The Cl"−-rich groundwater is contaminated by produced water brine and undergoes common ion induced carbonate precipitation. The δ"1"3C_D_I_C of the HCO_3"−-rich groundwater was controlled by nearly equal contribution of carbon from soil CO_2_(_g_) and the aquifer carbonates, such that the δ"1"3C of carbon added to the groundwater was −11.6‰. In the SO_4"2"−-rich groundwater, gypsum induced dedolomitization increased the "1"3C such that the δ"1"3C of carbon added to the groundwater was −9.4‰. In the produced water brine contaminated Cl"−-rich groundwater, common ion induced precipitation of calcite depleted the "1"3C such that the δ"1"3C of carbon added to the groundwater was −12.7‰. The results of this study demonstrate that produced water brine contamination of fresh groundwater in carbonate aquifers alters the carbonate and carbon isotopic evolution. - Highlights: • We studied carbonate and δ"1"3C evolution in groundwater contaminated by produced water brine. • Multiple processes affect the carbonate and δ"1"3C evolution of the groundwater. • The processes are carbonate weathering, dedolomitization and common ion induce calcite precipitation. • The δ"1"3C added to DIC was −11.6‰ for weathering, −9.4‰ for dedolomitization

Intermediate Temperature Fuel Cell Using Gypsum Based Electrolyte And Electrodes

International Nuclear Information System (INIS)

Suzuki, Satoshi; Nagai, Masayuki; Katagiri, Yuji

2011-01-01

The proton conductive electrolyte membrane and the electrodes for intermediate temperature fuel cell were made from the phosphoric acid treated gypsum as a proton conductor. The membrane and the electrodes were built into single cell and tested at intermediate temperature region. The power density of the fuel cell was 0.56 mW/cm -2 at 150 deg. C without any humidification and 1.38 mW/cm -2 at 150 deg. C, 5% relative humidity. The open circuit voltage of the cell was increased higher than 0.7 V when the electrodes were annealed at 150 deg. C, 5%R.H., however the reasons for this are still to be further investigated. The results show that the potential of the phosphoric acid treated gypsum for the intermediate temperature proton conductor.

Towards establishing a combined rate law of nucleation and crystal growth - The case study of gypsum precipitation

Science.gov (United States)

Rendel, Pedro M.; Gavrieli, Ittai; Wolff-Boenisch, Domenik; Ganor, Jiwchar

2018-03-01

The main obstacle in the formulation of a quantitative rate-model for mineral precipitation is the absence of a rigorous method for coupling nucleation and growth processes. In order to link both processes, we conducted a series of batch experiments in which gypsum nucleation was followed by crystal growth. Experiments were carried out using various stirring methods in several batch vessels made of different materials. In the experiments, the initial degree of supersaturation of the solution with respect to gypsum (Ωgyp) was set between 1.58 and 1.82. Under these conditions, heterogeneous nucleation is the dominant nucleation mode. Based on changes in SO42- concentration with time, the induction time of gypsum nucleation and the following rate of crystal growth were calculated for each experiment. The induction time (6-104 h) was found to be a function of the vessel material, while the rates of crystal growth, which varied over three orders of magnitude, were strongly affected by the stirring speed and its mode (i.e. rocking, shaking, magnetic stirrer, and magnetic impeller). The SO42- concentration data were then used to formulate a forward model that couples the simple rate laws for nucleation and crystal growth of gypsum into a single kinetic model. Accordingly, the obtained rate law is based on classical nucleation theory and heterogeneous crystal growth.

Cleaning the Produced Water in Offshore Oil Production by Using Plant-wide Optimal Control Strategy

DEFF Research Database (Denmark)

Yang, Zhenyu; Pedersen, Simon; Løhndorf, Petar Durdevic

2014-01-01

To clean the produced water is always a challenging critical issue in the offshore oil & gas industry. By employing the plant-wide control technology, this paper discussed the opportunity to optimize the most popular hydrocyclone-based Produced Water Treatment (PWT) system. The optimizations of t...... of this research is to promote a technical breakthrough in the PWT control design, which can lead to the best environmental protection in the oil & gas production, without sacrificing the production capability and production costs....

Characterization of gypsum crystals exposed to a high CO2 concentration fog using x-ray

International Nuclear Information System (INIS)

Carreño-Márquez, I. J. A.; Castillo-Sandoval, I.; Esparza-Ponce, H. E.; Fuentes-Cobas, L.; Montero-Cabrera, M. E.

2015-01-01

In Chihuahua State, a little town called Naica has the largest gypsum single crystals in the world. The growth of these structures has been described as a long and stable process developed over thousands of years. Due to the change in the environmental conditions, these crystals could suffer alterations on their surface. In this project we study the cause of possible deterioration of the giant crystals and intend to suggest measures for their preservation. For this sake, our first experiment consists on several gypsum crystals that have been subjected in a climate chamber to a fog at high CO 2 concentration and 51 °C for a period of time of six months, extracting two crystals every 15 days. Then the crystals have been characterized through Grazing Incidence X-Ray Diffraction using a diffractometer PanAlytical X’PertPro with two different detectors; Xe-filled proportional detector and a Pixel 3D detector. The results were compared to determine which technique is the most suitable to study the degradation of gypsum single crystals. In the two cases, we have identified only the gypsum phase, but with different crystal plane orientations

The influence of surface and incorporated lime and gypsiferous by-products on surface and subsurface soil acidity. II. Root growth and agronomic implications

Energy Technology Data Exchange (ETDEWEB)

Wang, H.L.; Hedley, M.J.; Bolan, N.S.; Horne, D.J. [New Zealand Forest Research Institute, Rotorua (New Zealand)

1999-04-01

Lucerne (Medicago sativa. L) root elongation in acid soils amended by gypsiferous coal combustion by-products was investigated in a glasshouse study. Lime, fluidised bed boiler ash (FBA), and flue gas desulfurisation gypsum (FGDG) were mixed into the surface 50 mm of either an Allophanic (the Patua sand loam) or an Ultic (the Kaawa clay loam) soil column, at rates containing calcium equivalent to 5000 kg/ha of CaCO{sub 3}. Lucerne was grown on each column after it was leached with 400 mm of water. Whereas the lime treatment had no effect on root elongation in the acidic subsurface of the Patua soil, the FBA and FGDG treatments significantly improved lucerne root penetration into the subsurface soil. This was due to the `self liming effect` induced by sulfate adsorption. In contrast, topsoil incorporated amendments did not influence root penetration into the acidic subsurface of the Kaawa soil, which is dominated by permanently charged clay minerals. The `self-liming erect` caused by gypsum application is not a sustainable practice. Lime should be applied to neutralise the topsoil acidity, when gypsum is used as subsurface soil acidity ameliorant. FBA, which contains both lime and gypsum, can meet these requirements.

Chitooligomers preparation by chitosanase produced under solid state fermentation using shrimp by-products as substrate.

Science.gov (United States)

Nidheesh, T; Pal, Gaurav Kumar; Suresh, P V

2015-05-05

Solid state fermentation (SSF) conditions were statistically optimized for the production of chitosanase by Purpureocillium lilacinum CFRNT12 using shrimp by-products as substrate. Central composite design and response surface methodology were applied to evaluate the effect of variables and their optimization. Incubation temperature, incubation time, concentration of inoculum and yeast extract were found to influence the chitosanase production significantly. The R(2) value of 0.94 indicates the aptness of the model. The level of variables for optimal production of chitosanase was 32 ± 1°C temperature, 96 h incubation, 10.5% (w/v) inoculum, 1.05% (w/w) yeast extract and 65% (w/w) moisture content. The chitosanase production was found to increase from 2.34 ± 0.07 to 41.78 ± 0.73 units/g initial dry substrate after optimization. The crude chitosanase produced 4.43 mM of chitooligomers as exclusive end product from colloidal chitosan hydrolysis. These results indicate the potential of P. lilacinum CFRNT12 for the chitosanase production employing cost effective SSF using shrimp by-products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production and characterization of di-rhamnolipid produced by Pseudomonas aeruginosa TMN

International Nuclear Information System (INIS)

Moussa, T. A. A.; Mohamed, M. S.; Samak, N.

2014-01-01

Pseudomonas aeruginosa TMN was used to produce rhamnolipid (RL) from a variety of carbon and nitrogen substrates. The most favorable carbon sources for RL production were glucose and glycerol (both at 40 g/L), giving a RL yield of 0.3 and 0.25 g/L, respectively. Meanwhile, sodium nitrate appeared to be the preferable nitrogen source, resulting in a RL production of 0.34g/L. Rhamnolipid production from P. aeruginosa TMN was affected by temperature, pH and agitation rate, with 37 °C, pH 7 and 200 rpm agitation favorable for rhamnolipid production. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and electro spray ionization-mass spectrometry (ESI-MS) analyses indicated that the purified product contained one type of commonly found rhamnolipid, which is L-rhamnosyl-L-rhamnosyl-β- hydroxydecanoyl-β-hydroxydecanoate. The rhamnolipid product can reduce the surface tension of water to 34 mN/m with a critical micelle concentration of nearly 18.75 mg/L and emulsified kerosene by 46%. P. aeruginosa TMN strain is a potential source of rhamnolipid biosurfactant, which could be used for the development of bioremediation processes in the marine environment. (author)

Production and characterization of di-rhamnolipid produced by Pseudomonas aeruginosa TMN

Energy Technology Data Exchange (ETDEWEB)

Moussa, T. A. A.; Mohamed, M. S.; Samak, N., E-mail: mervat_sayed@yahoo.com, E-mail: mervat@sci.cu.edu.eg [Cairo University (Egypt)

2014-10-15

Pseudomonas aeruginosa TMN was used to produce rhamnolipid (RL) from a variety of carbon and nitrogen substrates. The most favorable carbon sources for RL production were glucose and glycerol (both at 40 g/L), giving a RL yield of 0.3 and 0.25 g/L, respectively. Meanwhile, sodium nitrate appeared to be the preferable nitrogen source, resulting in a RL production of 0.34g/L. Rhamnolipid production from P. aeruginosa TMN was affected by temperature, pH and agitation rate, with 37 °C, pH 7 and 200 rpm agitation favorable for rhamnolipid production. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and electro spray ionization-mass spectrometry (ESI-MS) analyses indicated that the purified product contained one type of commonly found rhamnolipid, which is L-rhamnosyl-L-rhamnosyl-β- hydroxydecanoyl-β-hydroxydecanoate. The rhamnolipid product can reduce the surface tension of water to 34 mN/m with a critical micelle concentration of nearly 18.75 mg/L and emulsified kerosene by 46%. P. aeruginosa TMN strain is a potential source of rhamnolipid biosurfactant, which could be used for the development of bioremediation processes in the marine environment. (author)

Evolution of microstructure and elastic wave velocities in dehydrated gypsum samples

Science.gov (United States)

Milsch, Harald; Priegnitz, Mike

2012-12-01

We report on changes in P and S-wave velocities and rock microstructure induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air, at ambient pressure, and temperatures between 378 and 423 K. Dehydration did not proceed homogeneously but via a reaction front moving sample inwards separating an outer highly porous rim from the remaining gypsum which, above approximately 393 (±5) K, concurrently decomposed into hemihydrate. Overall porosity was observed to continuously increase with reaction progress from approximately 2% for fully hydrated samples to 30% for completely dehydrated ones. Concurrently, P and S-wave velocities linearly decreased with porosity from 5.2 and 2.7 km/s to 1.0 and 0.7 km/s, respectively. It is concluded that a linearized empirical Raymer-type model extended by a critical porosity term and based on the respective time dependent mineral and pore volumes reasonably replicates the P and S-wave data in relation to reaction progress and porosity.

A study of the effectiveness of the use of gypsum and volcanic ash against the stability of clay soil in terms of UCT and CBR values

Science.gov (United States)

Roesyanto; Iskandar, R.; Hastuty, IP; Lubis, AIU

2018-02-01

Soil stabilization is an effort to improve engineering properties of soil. The conventional soil stabilization is by adding additives to the soil such as Portland cement, lime, and bitumen. The clay stabilization research was done by adding gypsum and volcanic ash. The research purposes were to find out the value of engineering properties of clay due to the addition of 2% gypsum and 2% - 15% volcanic ash. The soil was classified as Clay - Low Plasticity (CL) based on USCS and was classified as A-7-6 (10) based on AASHTO classification system. The UCT values of original soil and original soil plus 2% gypsum were 1.40 kg/cm2 and 1.66 kg/cm2 respectively. The CBR soaked and unsoaked values of original soil were 4.44% and 6.28% correspondingly. Meanwhile, CBR soaked and CBR unsoaked values of original soil plus 2% gypsum were 6.74% and 8.02% respectively. The research results showed that the additives materials of gypsum and volcanic ash improved the engineering properties of clay. The UCT result from the stabilized soil by 2% gypsum and 10% volcanic ash gave value of 2.79 kg/cm2 (increased 99.28% from original soil). For CBR test, the most effective mixture were in variation of 2% gypsum and 9% volcanic ash which gave value of 9.07% (104.27% increase from original soil) for CBR soaked and 10.29% (63.85% increase from original soil) for CBR unsoaked. The stabilized soil with 2% gypsum and 9% volcanic ash was classified as CL based on USCS and was classified as A-6 (4) based on AASHTO classification system.

Production of press moulds by plasma spray forming process

International Nuclear Information System (INIS)

Borisov, Y.; Myakota, I.; Polyakov, S.

2001-01-01

Plasma spray forming process for production of press moulds which are used for manufacture of articles from plastics was developed. The press moulds were produced by plasma spraying of Cu-Al-Fe-alloy powder on surface of a master model. The master models were made from non-metallic materials with heat resistance below 70 C (wood, gypsum etc). Double cooling system which provides for a control of surface model temperature and quenching conditions of sprayed material was designed. It made possible on the one hand to support model surface temperature below 70 C and on the other hand to provide for temperature conditions of martensite transformation in Cu-Al-system with a fixation of metastable ductile α + β 1 -phase. This allowed to decrease residual stresses in sprayed layer (up to 0,5-2,5 MPa), to increase microhardness of the coating material (up to 1200-1800 MPa) and its ductility (σ B = 70-105 MPa, δ = 6-12 %). This plasma spray forming process makes possible to spray thick layers (5-20 mm and more) without their cracking and deformation. The process is used for a production of press moulds which are applied in shoes industry, for fabrication of toys, souvenirs etc. (author)

The semidry acid-anhydrite process (the use of flue gas desulphurization (FGD) gypsum by development of a new process for the production of FGD anhydrite); Das quasitrockene Saeure-Anhydrit-Verfahren (Erweiterung der Verwendungsmoeglichkeiten von REA-Gips durch Entwicklung eines Verfahrens zur Herstellung von REA-Anhydrit aus REA-Gips)

Energy Technology Data Exchange (ETDEWEB)

Wirsching, F. [Gebr. Knauf, Westdeutsche Gipswerke, Iphofen (Germany); Hueller, R. [Gebr. Knauf, Westdeutsche Gipswerke, Iphofen (Germany); Limmer, B. [Gebr. Knauf, Westdeutsche Gipswerke, Iphofen (Germany)

1994-10-01

A completely new reaction for conversion of FGD gypsum into FGD anhydrite was investigated in the research project which forms the basis for this article. The reaction takes place with moist, finely divided, FGD gypsum with the catalytic action of small quantities of sulphuric acid at temperatures around 100 to 200 C. Moisture-free FGD anhydrite with an orthorhombic crystalline structure ist obtained. The conversion of the crystalline lattice of calcium sulphate dihydrate into calcium anhydrite II takes place directly through neoformation. This conversion is developed into a new process called the `Semidry Acid-Anhydrite Process`. The reaction and its mechanism were first investigated in laboratory trials. Any finely divided calcium sulphate dihydrate is suitable as the starting material. The FGD gypsum with 10% residual moisture, which is already in a finely divided crystalline state when it is generated in the power station, is particularly advantageous as for this application it does not have to be dried or ground first. The process development was carried out up to a semi-industrial scale and the design principles were worked out for large-scale plants at power station sites. The directly heated rotary tube kiln proved to be a suitable reaction unit. The FGD anhydrite is obtained in this process as a dry, finely divided, product with reproducible properties. Investigations were carried out into its potential applications for the cement industry and as a raw material for producing fillers. In principle it is suitable for the cement industry. Applications as a filler allows the FGD gypsum to extend its uses outside the traditional areas of the gypsum industry. Initial trials indicate that after a processing procedure, which was also newly developed in the laborator, FGD anhydrite processes the characteristic features necessary for a high grade filler. (orig.) [Deutsch] In dem Forschungsprojekt wurde eine voellig neue Umwandlungsreaktion von REA-Gips in REA

Recovery of uranium in the production of concentrated phosphoric acid by a hemihydrate process

International Nuclear Information System (INIS)

Nakajima, S.; Miyamoto, M.

1983-01-01

Nissan Chemical Industries as manufacturers of phosphoric acid have studied the recovery of uranium, based on a concentrated phosphoric acid production process. The process consists of two stages, a hemihydrate stage with a formation of hemihydrate and a filtration section, followed by a dihydrate stage with hydration and a filtration section. In the hemihydrate stage, phosphate is treated with a mixture of phosphoric acid and sulphuric acid to produce phosphoric acid and hydrous calcium sulphate; the product is recovered in the filtration section and its concentration is 40-50% P 2 O 3 . In the dihydrate stage, the hemihydrate is transformed by re-dissolution and hydration, producing hydrous calcium sulphate, i.e. gypsum. This process therefore comprises two parts, each with different acid concentrations. As the extraction of uranium is easier in the case of a low concentration of phosphoric acid, the process consists of the recovery of uranium starting from the filtrate of the hydration section. The tests have shown that the yield of recovery of uranium was of the order of 80% disregarding the handling losses and no disadvantageous effect has been found in the combination of the process of uranium extraction with the process of concentrated phosphoric acid production. Compared with the classical process where uranium is recovered from acid with 30% P 2 O 5 , the process of producing high-concentration phosphoric acid such as the Nissan process, in which the uranium recovery is effected from acid with 15% P 2 O 5 from the hydration section, presents many advantages [fr

Sulfates removal by the GYP-CIX process following lime treatment

International Nuclear Information System (INIS)

Robertson, A.M.; Everett, D.J.; Plessis, N.J. Du

1994-01-01

The treatment of acid mine drainage by limiting results in the discharge of water saturated in gypsum and containing residual metal concentrations. These waters may exceed drinking and irrigation water standards for TDS, sulfates and some metals. The scaling nature of the saturated gypsum solution makes it unsuitable for industrial use and makes further processing difficult and costly. This paper discusses a novel ion exchange process that is suitable to desalinate large volumes of mine and industrial waters with a TDS of up to 6,500 mg/l which is also high in calcium and sulfates, to meet effluent discharge specifications. The GYP-CIX process is a continuous fluidized bed ion-exchange process that effectively removes calcium sulfate from gypsum saturated waters. It uses low cost chemicals such as lime and sulfuric acid for resin regeneration. The only waste product is gypsum and the treated water produced meets standards for reuse or discharge. This process consists of a two stage operation. The first is the removal of cations in a multistage continuous loading train, using cation exchange resin. The second operation is the removal of anions, again in a multistage continuous loading train using anion exchange resin

Gypsum crystals in the inner shelf sediments off Maharashtra, India

Digital Repository Service at National Institute of Oceanography (India)

Hashimi, N.H.; Ambre, N.V.

Gypsum crystals have been found in the inner shelf silty clay/clayey silt off the Maharashtra Coast between Vengurla and Bombay. Generally these occur as euhedral single or twinned crystals of selenite. Very often shells are found embedded within...

Simultaneous and continuous stabilization of As and Pb in contaminated solution and soil by a ferrihydrite-gypsum sorbent.

Science.gov (United States)

Kameda, Kentaro; Hashimoto, Yohey; Wang, Shan-Li; Hirai, Yasumasa; Miyahara, Hidetaka

2017-04-05

For the increasing need of stabilization both cationic and anionic metal(loid)s simultaneously, we newly developed a metal sorbent (FIXALL), consisting mainly of ferrihydrite and gypsum. The objectives of this study were to determine the molecular mechanisms of Pb and As stabilization in an aqueous system and to examine a simultaneous and long-term (up to 754days) effect on Pb and As stabilization in an anthropogenically contaminated soil using the FIXALL sorbent. When the solution contained a low concentration of Pb (5mgL -1 ), the mechanisms of Pb removal by FIXALL were based chiefly on the formation of inner-sphere surface complex with ferrihydrite. In the highly concentrated Pb solution (1200mgL -1 ), contrarily, the removal of Pb by FIXALL was the direct consequence of the dissolution of gypsum and subsequent precipitation of PbSO 4 , which strengthens the drawback of low capability of ferrihydrite for Pb removal. Regardless of initial concentrations, the primary mechanism of FIXALL for As stabilization is attributed to the formation of inner-sphere surface complex with ferrihydrite. A contaminated soil study demonstrated that FIXALL could decrease the concentration of water soluble As and Pb simultaneously and continuously for 754days without notable changes in their chemical species and soil pH. Copyright © 2016 Elsevier B.V. All rights reserved.

In Situ Observation of Gypsum-Anhydrite Transition at High Pressure and High Temperature

International Nuclear Information System (INIS)

Liu Chuan-Jiang; Zheng Hai-Fei

2012-01-01

An in-situ Raman spectroscopic study of gypsum-anhydrite transition under a saturated water condition at high pressure and high temperature is performed using a hydrothermal diamond anvil cell (HDAC). The experimental results show that gypsum dissolvs in water at ambient temperature and above 496 MPa. With increasing temperature, the anhydrite (CaSO 4 ) phase precipitates at 250–320°C in the pressure range of 1.0–1.5GPa, indicating that under a saturated water condition, both stable conditions of pressure and temperature and high levels of Ca and SO 4 ion concentrations in aqueous solution are essential for the formation of anhydrite. A linear relationship between the pressure and temperature for the precipitation of anhydrite is established as P(GPa) = 0.0068T−0.7126 (250°C≤T≤320°C). Anhydrite remained stable during rapid cooling of the sample chamber, showing that the gypsum-anhydrite transition involving both dissolution and precipitation processes is irreversible at high pressure and high temperature. (geophysics, astronomy, and astrophysics)

Development of a self-compacting gypsum-based lightweight composite

NARCIS (Netherlands)

Yu, Q.; Brouwers, H.J.H.

2012-01-01

This article addresses experiments and theories of a self-compacting gypsum-based lightweight composite (SGLC). A ß-hemihydrate is used as binder and lightweight aggregate (LWA, 0–2 mm in different size ranges) is used as aggregate into this composite. The mix of the new composite is designed based

High-yield synthesis of vaterite microparticles in gypsum suspension system via ultrasonic probe vibration/magnetic stirring

Science.gov (United States)

Wang, Bo; Pan, Zihe; Cheng, Huaigang; Chen, Zuliang; Cheng, Fangqin

2018-06-01

Vaterite-type calcium carbonate particles have some unique properties such as high hydrophilicity, large surface areas, and hierarchical structures consisting of primary vaterite particles in comparison with calcite or aragonite-type polymorphs. In this paper, gypsum (CaSO4·2H2O) suspension is used to synthesize micro-sized vaterite CaCO3 through magnetic stirring (MS) and ultrasonic probe vibration (UPV) methods. The effects of ammonia concentration, CO2 flow rate, solid-liquid ratio on the gypsum carbonation process, mineral phase composition, morphology and particle size distribution of CaCO3 are investigated. The results show that the carbonation process is significantly influenced by ammonia concentration, CO2 flow rate and ultrasound. Comparing with magnetic stirring, ultrasonic probe vibration take less time to reach the complete carbonate reaction. Gypsum is transformed to vaterite with the conversion rate about ∼95% when the mole ratio of NH4+/Ca2+ is 2.4 otherwise the carbonation reaction was uncompleted with gypsum residues left. Comparing with MS method, the UPV method resulted in smaller size and narrower size distribution of as-prepared microparticles and approximately 80% reduction of the particle size was achieved. It is established that increasing the solid-liquid ratio resulted in larger particle size in MS system and smaller particle size in UPV system. Increasing CO2 flow rate caused the particle size decreased in MS system and increased in UPV system.

Late Glacial temperature and precipitation changes in the lowland Neotropics by tandem measurement of δ 18O in biogenic carbonate and gypsum hydration water

Science.gov (United States)

Hodell, David A.; Turchyn, Alexandra V.; Wiseman, Camilla J.; Escobar, Jaime; Curtis, Jason H.; Brenner, Mark; Gilli, Adrian; Mueller, Andreas D.; Anselmetti, Flavio; Ariztegui, Daniel; Brown, Erik T.

2012-01-01

We applied a new method to reconstruct paleotemperature in the tropics during the last deglaciation by measuring oxygen isotopes of co-occurring gypsum hydration water and biogenic carbonate in sediment cores from two lakes on the Yucatan Peninsula. Oxygen and hydrogen isotope values of interstitial and gypsum hydration water indicate that the crystallization water preserves the isotopic signal of the lake water, and has not undergone post-depositional isotopic exchange with sediment pore water. The estimated lake water δ18O is combined with carbonate δ18O to calculate paleotemperature. Three paired measurements of 1200-yr-old gypsum and gastropod aragonite from Lake Chichancanab, Mexico, yielded a mean temperature of 26 °C (range 23-29.5 °C), which is consistent with the mean and range of mean annual temperatures (MAT) in the region today. Paired measurements of ostracods, gastropods, and gypsum hydration water samples were measured in cores from Lake Petén Itzá, Guatemala, spanning the Late Glacial and early Holocene period (18.5-10.4 ka). The lowest recorded temperatures occurred at the start of Heinrich Stadial (HS) 1 at 18.5 ka. Inferred temperatures from benthic ostracods ranged from 16 to 20 °C during HS 1, which is 6-10 °C cooler than MAT in the region today, whereas temperatures derived from shallow-water gastropods were generally warmer (20-25 °C), reflecting epilimnetic temperatures. The derived temperatures support previous findings of greater tropical cooling on land in Central America during the Late Glacial than indicated by nearby marine records. Temperature increased in two steps during the last deglaciation. The first occurred during the Bolling-Allerod (B-A; from 14.7 to 13 ka) when temperature rose to 20-24 °C towards the end of this period. The second step occurred at 10.4 ka near the beginning of the Holocene when ostracod-inferred temperature rose to 26 °C, reflecting modern hypolimnetic temperature set during winter, whereas

Gypsum plasterboards enhanced with phase change materials: A fire safety assessment using experimental and computational techniques

Directory of Open Access Journals (Sweden)

Kolaitis Dionysios I.

2013-11-01

Full Text Available Phase Change Materials (PCM can be used for thermal energy storage, aiming to enhance building energy efficiency. Recently, gypsum plasterboards with incorporated paraffin-based PCM blends have become commercially available. In the high temperature environment developed during a fire, the paraffins, which exhibit relatively low boiling points, may evaporate and, escaping through the gypsum plasterboard's porous structure, emerge to the fire region, where they may ignite, thus adversely affecting the fire resistance characteristics of the building. Aiming to assess the fire safety behaviour of such building materials, an extensive experimental and computational analysis is performed. The fire behaviour and the main thermo-physical physical properties of PCM-enhanced gypsum plasterboards are investigated, using a variety of standard tests and devices (Scanning Electron Microscopy, Thermo Gravimetric Analysis, Cone Calorimeter. The obtained results are used to develop a dedicated numerical model, which is implemented in a CFD code. CFD simulations are validated using measurements obtained in a cone calorimeter. In addition, the CFD code is used to simulate an ISO 9705 room exposed to fire conditions, demonstrating that PCM addition may indeed adversely affect the fire safety of a gypsum plasterboard clad building.

Effect Of Coir Fibres On The Compaction And Unconfined Compressive Strength Of Bentonite-Lime-Gypsum Mixture

Directory of Open Access Journals (Sweden)

Tilak B. Vidya

2015-06-01

Full Text Available This paper presents the effect of coir fibres on the compaction and unconfined compressive strength of a bentonite-lime-gypsum mixture. The coir fiber content varied from 0.5 to 2 %. The results indicated that the dry unit weight and the optimum moisture content of a bentonite – lime mix increased with the addition of gypsum. The unconfined compressive strength of the bentonite increased with the increase in the lime content up to 8 %. Beyond 8 %, the unconfined compressive strength decreased. The dry unit weight of the reference mix decreased, and the optimum moisture content increased with the addition of coir fibre. The unconfined compressive strength of the bentonite + 8 % lime mix increased up to 4 % with the gypsum. Beyond 4 %, the unconfined compressive strength decreased. The unconfined compressive strength of the reference mix increased with the addition of coir fibre up to a fibre content of 1.5 %. The unconfined compressive strength of the reference mix-coir fibre composite was less in comparison to the reference mix. The unconfined compressive strength of the bentonite increased with the addition of lime and gypsum and with the increase in the curing period. The improvement in the post-peak region was better for the reference mix with reinforced coir fibres as compared to the unreinforced reference mix. The improved post-peak behaviour of the bentonite-lime-gypsum-coir fibre mixture could boost the construction of temporary roads on such problematic soils. Further, its use will also provide an environmental motivation for providing a means of consuming large quantities of coir fibres.

Recovery of soil physical properties by green manure, liming, gypsum and pasture and spontaneous native species¹

Directory of Open Access Journals (Sweden)

Carolina dos Santos Batista Bonini

2011-08-01

Full Text Available Inadequate usage can degrade natural resources, particularly soils. More attention has been paid to practices aiming at the recovery of degraded soils in the last years, e.g, the use of organic fertilizers, liming and introduction of species adapted to adverse conditions. The purpose of this study was therefore to investigate the recovery of physical properties of a Red Latosol (Oxisol degraded by the construction of a hydroelectric power station. In the study area, a soil layer about 8m thick had been withdrawn by heavy machines leading not only to soil compaction, but resulting in high-degree degradation. The experiment was arranged in a completely randomized design with nine treatments and four replications. The treatments consisted of: 1- soil mobilization by tilling (to ensure the effect of mechanical mobilization in all treatments without planting, but growth of spontaneous vegetation; 2- Black velvet bean (Stizolobium aterrimum Piper & Tracy; 3- Pigeonpea (Cajanus cajan (L. DC; 4- Liming + black velvet bean; 5-Liming + pigeonpea until 1994, when replaced by jack bean (Canavalia ensiformis; 6- Liming + gypsum + black velvet bean; 7- Liming + gypsum + pigeonpea until 1994, when replaced by jack bean; and two controls as reference: 8- Native Cerrado vegetation and 9- bare soil (no tilling and no planting, left under natural conditions and in this situation, without spontaneous vegetation. In treatments 1 through 7, the soil was tilled. Treatments were installed in 1992 and left unmanaged for seven years, until brachiaria (Brachiaria decumbens was planted in all plots in 1999. Seventeen years after implantation, the properties soil macroporosity, microporosity, total porosity, bulk density and aggregate stability were assessed in the previously described treatments in the soil layers 0.00-0.10; 0.10-0.20 and 0.20-0.40 m, and soil Penetration Resistance and soil moisture in 0.00-0.15 and 0.15-0.30 m. The plants were evaluated for: brachiaria

Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Wael Ahmed Abou Taleb Sayed

2011-01-13

This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

The production of precipitated calcium carbonate from industrial gypsum wastes

CSIR Research Space (South Africa)

De Beer, Morris

2014-05-01

Full Text Available -step) process was tested. Although only a low-grade CaCO3 product (86-88 mass% as CaCO3) could be produced, experimental results on the characteristics of CaS in the presence of CO2 in the CaS-H2O-CO2 system showed that the reaction proceeded in two distinct... stages. In the first stage, CaS dissolution took place, with H2S stripping occurring in the second stage. Calcium carbonation and the resulting precipitation of CaCO3 were concurrent with the CaS dissolution and the H2S stripping reactions. Because...

Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

KAUST Repository

Chen, Si Cong

2013-11-08

We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

Analyzing the rules of fracture and damage, and the characteristics of the acoustic emission signal of a gypsum specimen under uniaxial loading

Science.gov (United States)

Chen, Dong; Wang, En-yuan; Li, Nan

2017-08-01

In order to study the mechanism of rock bursts in a mined-out area of a gypsum mine, in this paper acoustic emission testing of the uniaxial compression of gypsum and sandstone samples is carried out. The case of rupture of the specimen is observed, and the load axial deformation curve and acoustic emission parameters are obtained for the whole process of specimen rupture. The similarities and differences between the gypsum and sandstone samples are determined in terms of their mechanical properties, their damage evolution laws and frequency band energy distributions, and the instantaneous energy characteristics of their acoustic emission. The results show that the main fracture morphology of gypsum is ‘eight’-type, and the macroscopic fracture morphology of sandstone is mainly of partial ‘Y’-type and inverted Y-type. The intensity and uniformity of the gypsum and sandstone of the medium are different; because the gypsum is more uniform, it does not show as much variation as sandstone, instead suddenly increasing and decreasing. The maximum value of the damage variable D of gypsum reached 1, but the maximum value of D of the sandstone only reached 0.9. The frequency band of the maximum energy of gypsum and sandstone gradually decreased across the the four stages of rupture, while the maximum energy percentage increased gradually. From the stage where damage gradually increases to the stage of integral fracture of the specimen, the instantaneous energy showed a certain degree of increase. With an increase in the strength of the sample, the maximum energy percentage of the two materials corresponding to each phase gradually increases, and from the stage where damage gradually increases to the stage of integral fracture of the specimen, the value of instantaneous energy obviously increases. The results indicate that gypsum mines will also experience rock bursts, as coal mines do, but the intensity will be different. Therefore, using the three indicators, the

GM-CSF and IL-4 produced by NKT cells inversely regulate IL-1β production by macrophages.

Science.gov (United States)

Ahn, Sehee; Jeong, Dongjin; Oh, Sae Jin; Ahn, Jiye; Lee, Seung Hyo; Chung, Doo Hyun

2017-02-01

Natural Killer T (NKT) cells are distinct T cell subset that link innate and adaptive immune responses. IL-1β, produced by various immune cells, plays a key role in the regulation of innate immunity in vivo. However, it is unclear whether NKT cells regulate IL-1β production by macrophages. To address this, we co-cultured NKT cells and peritoneal macrophages in the presence of TCR stimulation and inflammasome activators. Among cytokines secreted from NKT cells, GM-CSF enhanced IL-1β production by macrophages via regulating LPS-mediated pro-IL-1β expression and NLRP3-dependent inflammasome activation, whereas IL-4 enhanced M2-differentiation of macrophages and decreased IL-1β production. Together, our findings suggest the NKT cells have double-sided effects on IL-1β-mediated innate immune responses by producing IL-4 and GM-CSF. These findings may be helpful for a comprehensive understanding of NKT cell-mediated regulatory mechanisms of the pro-inflammatory effects of IL-1β in inflammatory diseases in vivo. Copyright © 2017 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

Coal combustion products: trash or treasure?

Energy Technology Data Exchange (ETDEWEB)

Hansen, T.

2006-07-15

Coal combustion by-products can be a valuable resource to various industries. The American Coal Ash Association (ACAA) collects data on production and uses of coal combustion products (CCPs). 122.5 million tons of CCPs were produced in 2004. The article discusses the results of the ACCA's 2004 survey. Fly ash is predominantly used as a substitute for Portland cement; bottom ash for structural fill, embankments and paved road cases. Synthetic gypsum from the FGD process is commonly used in wallboard. Plant owners are only likely to have a buyer for a portion of their CCPs. Although sale of hot water (from Antelope Valley Station) from condensers for use in a fish farm to raise tilapia proved unviable, the Great Plains Synfuels Plant which manufactures natural gas from lignite produces a wide range of products including anhydrous ammonia, phenol, krypton, carbon dioxide (for enhanced oil recovery), tar oils and liquid nitrogen. ACCA's goal is to educate people about CCPs and how to make them into useful products, and market them, in order to reduce waste disposal and enhance revenue. The article lists members of the ACCA. 2 photos., 1 tab.

Study of extremely low frequency electromagnetic field (ELF EMF) radiation produced by consumer products

International Nuclear Information System (INIS)

Roha Tukimin; Ahmad Fazli Ahmad Sanusi; Rozaimah Abd Rahim; Mohd Yusof Mohd Ali; Mohamad Amirul Nizam Mohamad Thari

2006-01-01

Extremely low frequency electromagnetic field ( ELF EMF) radiation falls under category of non-ionising radiation (NIR).ELF EMF consists of electric and magnetic fields. Excessive exposure to ELF EMF radiation may cause biological and health effects to human beings such as behavioral changes, stochastic and as initiator of cancer. In daily life, the main source of extremely low frequency electromagnetic radiation are consumer products in our home and office. Due to its ability to cause hazard, a study of ELF EMF radiation produced by consumer product was conducted. For this preliminary study, sample of 20 types electrical appliances were selected. The measurement was covered electric and magnetic field strength produced by the sample. PMM model EHP50A were used for measurement and data analysis. The results were compared with the permissible limits recommended by International Commission of Non-Ionising Radiation Protection (ICNIRP) for members of public (1000 mGauss and 5000 V/m). The results showed that all tested sample produced magnetic and electric field but still under the permissible limit recommended by ICNIRP. Besides that we found that field strengths can be very high at closer distance to the sample. (Author)

Bacteriocin producers from traditional food products

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Thonart P.

2007-01-01

Full Text Available A total of 220 strains of LAB isolated from 32 samples of traditional fermented food from Senegal were screened for bacteriocin production. Two bacteriocin producers, Lactococcus lactis subsp. lactis and Enterococcus faecium, were identified from 12 bacteriocin-producing isolates on the basis of phenotypic analyses and 16S rDNA sequence. Both bacteriocins produced by new isolates show antimicrobial activity against Listeria monocytogenes and Bacillus coagulans whereas only that produced by Lactococcus lactis has an activity against Bacillus cereus. Bacteriocin-producing Lactococcus lactis strains were found in a variety of traditional foods indicating a high potential of growth of this strain in variable ecological complex environment. Partial 16S rDNA of the two bacteriocin producers obtained in this study has been registered to Genbank databases under the accession number AY971748 for Lactococcus lactis subsp. lactis (named CWBI-B1410 and AY971749 for Enterococcus faecium (named CWBI-B1411. The new bacteriocin-producing Lactococcus lactis subsp. lactis strain has been selected for identification and application of the bacteriocin to food preservation.

Power Producer Production Valuation

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M. Kněžek

2008-01-01

Full Text Available The ongoing developments in the electricity market, in particular the establishment of the Prague Energy Exchange (PXE and the associated transfer from campaign-driven sale to continuous trading, represent a significant change for power companies.  Power producing companies can now optimize the sale of their production capacities with the objective of maximizing profit from wholesale electricity and supporting services. The Trading Departments measure the success rate of trading activities by the gross margin (GM, calculated by subtracting the realized sales prices from the realized purchase prices and the production cost, and indicate the profit & loss (P&L to be subsequently calculated by the Control Department. The risk management process is set up on the basis of a business strategy defining the volumes of electricity that have to be sold one year and one month before the commencement of delivery. At the same time, this process defines the volume of electricity to remain available for spot trading (trading limits. 

Effect of Organic Matter and Gypsum Powder Some Traits of Maize in a Saline-Sodic Soil

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M Khotabaee

2015-04-01

Full Text Available Saline-sodic soils have improper physical, chemical and biological condition and the crop productivity is low in these conditions. Application of conditioners often can be a proper solution for reclamation and improving the productivity of saline-sodic soils. In order to study the effect of some conditioners on soil chemical characteristics and yield of maize (SC260 cultivar in a saline-sodic soil, an experiment was carried out as a completely randomized design with 3 replications in a research greenhouse of Ferdowsi university of Mashhad. The studied treatments included control and 10 ton/ha of compost (MC, vermi-compost (VC, poultry manure (PM, and gypsum powder (G. The results showed that poultry manure and vemi-compost treatments increased significantly (p

Fabrication of calcite blocks from gypsum blocks by compositional transformation based on dissolution-precipitation reactions in sodium carbonate solution.

Science.gov (United States)

Ishikawa, Kunio; Kawachi, Giichiro; Tsuru, Kanji; Yoshimoto, Ayami

2017-03-01

Calcium carbonate (CaCO 3 ) has been used as a bone substitute, and is a precursor for carbonate apatite, which is also a promising bone substitute. However, limited studies have been reported on the fabrication of artificial calcite blocks. In the present study, cylindrical calcite blocks (ϕ6×3mm) were fabricated by compositional transformation based on dissolution-precipitation reactions using different calcium sulfate blocks as a precursor. In the dissolution-precipitation reactions, both CaSO 4 ·2H 2 O and CaSO 4 transformed into calcite, a polymorph of CaCO 3 , while maintaining their macroscopic structure when immersed in 1mol/L Na 2 CO 3 solution at 80°C for 1week. The diametral tensile strengths of the calcite blocks formed using CaSO 4 ·2H 2 O and CaSO 4 were 1.0±0.3 and 2.3±0.7MPa, respectively. The fabrication of calcite blocks using CaSO 4 ·2H 2 O and CaSO 4 proposed in this investigation may be a useful method to produce calcite blocks because of the self-setting ability and high temperature stability of gypsum precursors. Copyright © 2016 Elsevier B.V. All rights reserved.

Aspergillus species as mycotoxin producers in agricultural products in central Europe

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Kočube Šandor

2013-01-01

Full Text Available Aspergillus species are able to produce a range of mycotoxins, includ­ing e.g. aflatoxins, ochratoxins, fumonisins and patulin. Aflatoxins are mainly produced by members of Aspergillus section Flavi, and they contaminate various agricultural products in several parts of the world. Several recent reports have indicated that aflatoxin-producing fungi and consequently aflatoxin contamination occur in agricultural commodities in a number of European countries which have not been faced with this problem before. Indeed, recent surveys have clarified that concentrations of aflatoxins in maize products and milk has been exceeding the EU limit in several regions of Central Europe including Serbia, Slovenia, Croatia, Northern Italy and Romania. However, aflatoxin contamination and aflatoxin-producing Aspergillus species have not been identified yet in maize in Hungary. We examined the presence of potential aflatoxin-producing Aspergilli in maize samples collected in southern parts of Hungary. Several A. flavus isolates were identified, and pre­liminary results indicated that some of the isolates were able to produce aflatoxins. Con­tamination of other agricultural products with aflatoxins can also pose problems in Central Europe due to global warming. Ochratoxin contamination of grapes and grape-derived products is usually caused by black Aspergilli, especially by A. carbonarius and A. niger, although these species have been rare in Central European vineyards due to climatic fac­tors. Ochratoxin contamination of other agricultural products including spices and cereals was also observed in the region. Besides, ochratoxin producing Aspergilli are frequently isolated from imported products including coffee beans, dried fruits and spices, and ochra­toxin contamination of these samples was also observed. Fumonisins are produced mainly by Fusarium species, and by the recently identified producers Aspergillus niger and A. awamori. We examined fumonisin

Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard

Science.gov (United States)

This page contains documents related to the evaluation of coal combustion residual beneficial use of fly ash concrete and FGD gypsum wallboard including the evaluation itself and the accompanying appendices

Physical, chemical and radioactive characterization of co-products from titanum dioxide industry for valorization in the cement industry; Caracterizacion fisico-quimica y radiactiva de los sub-productos provenientes de la industria de dioxido de titanio para su valorizacion en la industria del cemento: implicaciones radiologicas.

Energy Technology Data Exchange (ETDEWEB)

Gazquez, M.J.; Mantero, J.; Bolivar, J.P.; Garcia-Tenorio, R.; Vaca, F.

2011-07-01

The present study was conducted to characterize the raw materials (ilmenite and slag), waste (red gypsum) and several co-products (sulphate monohydrate and sulphate heptahydrated) form the titanum dioxide industry in relation to their elemental composition (major, minor and trace elements), granulometry, mineralogy, microscopic morphology, physical composition and radioactive content in order to apply this knowledge in the valorization of the co-products in the fields sucha as construction, civil engineering, etc. In particular, the main properties of cements produced with different proportions of red gypsum were studied, and the obtained improvements, in relation to Ordinary Portland Cements (OPC) were evaluated. It was also demonstrated that the levels of pollutants and the radioactive content in the produced RG cements, remain within the regulated safety limits. (Author). 38 refs.

Physical, chemical and radioactive characterization of co-products from titanium dioxide industry for valorization in the cement industry; Caracterizacion fisico-quimica y radiactiva de los sub-productos provenientes de la industria de dioxido de titanio para su valorizacion en la industria del cemento: implicaciones radiologicas.

Energy Technology Data Exchange (ETDEWEB)

Gazquez, M.J.; Mantero, J.; Bolivar, J.P.; Garcia-Tenorio, R.; Vaca, F.

2011-07-01

The present study was conducted to characterize the raw materials (ilmenite and slag), waste (red gypsum) and several co-products (sulphate monohydrate and sulphate heptahydrated) form the titanium dioxide industry in relation to their elemental composition (major, minor and trace elements), granulometry, mineralogy, microscopic morphology, physical composition and radioactive content in order to apply this knowledge in the valorization of the co-products in the fields such a as construction, civil engineering, etc. In particular, the main properties of cements produced with different proportions of red gypsum were studied, and the obtained improvements, in relation to Ordinary Portland Cements (OPC) were evaluated. It was also demonstrated that the levels of pollutants and the radioactive content in the produced RG cements, remain within the regulated safety limits. (Author). 38 refs.

Aliphatic alcohols of illegally produced spirits can act synergistically on superoxide-anion production by human granulocytes.

Science.gov (United States)

Arnyas, Ervin M; Pál, László; Kovács, Csilla; Adány, Róza; McKee, Martin; Szűcs, Sándor

2012-10-01

Aliphatic alcohols present in illegally produced spirits in a large number of low and middle income countries have been implicated in the etiology of chronic liver disease and cirrhosis. Previous studies have confirmed that chronic alcoholism can lead to increased susceptibility to infectious diseases. Reduced superoxide-anion (O(2)·(-)) production by granulocytes could provide a mechanism by which antimicrobial defense is impaired in alcoholics. In vitro experiments have also demonstrated that ethanol can inhibit granulocyte O(2)·(-) generation. Aliphatic alcohols consumed as contaminants of illicit spirits may also influence O(2)·(-) production thereby contributing to a decrease in microbicidal activity. The aim of this study was to investigate this possibility. It measured the O(2)·(-) production by human granulocytes following treatment of the cells with aliphatic alcohol contaminants found in illicit spirits. Granulocytes were isolated from human buffy coats with centrifugal elutriation and then treated with individual aliphatic alcohols and their mixture. The O(2)·(-) production was stimulated with phorbol-12-13-dibutyrate and N-formyl-methionyl-leucyl-phenylalanine (FMLP) and measured by superoxide dismutase inhibitable reduction of ferricytochrome c. Aliphatic alcohols of illegally produced spirits inhibited the FMLP-induced O(2)·(-) production in a concentration dependent manner. They suppressed O(2)·(-) generation at 2.5-40 times lower concentrations when combined than when tested individually. Aliphatic alcohols found in illegally produced spirits can inhibit FMLP-induced O(2)·(-) production by granulocytes in a concentration-dependent manner. Due to their synergistic effects, it is possible that, in combination with ethanol, they may inhibit O(2)·(-) formation in heavy episodic drinkers.

Production and characterization of antifungal compounds produced by Lactobacillus plantarum IMAU10014.

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HaiKuan Wang

Full Text Available Lactobacillus plantarum IMAU10014 was isolated from koumiss that produces a broad spectrum of antifungal compounds, all of which were active against plant pathogenic fungi in an agar plate assay. Two major antifungal compounds were extracted from the cell-free supernatant broth of L. plantarum IMAU10014. 3-phenyllactic acid and Benzeneacetic acid, 2-propenyl ester were carried out by HPLC, LC-MS, GC-MS, NMR analysis. It is the first report that lactic acid bacteria produce antifungal Benzeneacetic acid, 2-propenyl ester. Of these, the antifungal products also have a broad spectrum of antifungal activity, namely against Botrytis cinerea, Glomerella cingulate, Phytophthora drechsleri Tucker, Penicillium citrinum, Penicillium digitatum and Fusarium oxysporum, which was identified by the overlay and well-diffusion assay. F. oxysporum, P. citrinum and P. drechsleri Tucker were the most sensitive among molds.

Products of an Artificially Induced Hydrothermal System at Yucca Mountain

International Nuclear Information System (INIS)

Levy, S.

2000-01-01

Studies of mineral deposition in the recent geologic past at Yucca Mountain, Nevada, address competing hypotheses of hydrothermal alteration and deposition from percolating groundwater. The secondary minerals being studied are calcite-opal deposits in fractures and lithophysal cavities of ash-flow tuffs exposed in the Exploratory Studies Facility (ESF), a 7.7-km tunnel excavated by the Yucca Mountain Site Characterization Project within Yucca Mountain. An underground field test in the ESF provided information about the minerals deposited by a short-lived artificial hydrothermal system and an opportunity for comparison of test products with the natural secondary minerals. The heating phase lasted nine months, followed by a nine-month cooling period. Natural pore fluids were the only source of water during the thermal test. Condensation and reflux of water driven away from the heater produced fluid flow in certain fractures and intersecting boreholes. The mineralogic products of the thermal test are calcite-gypsum aggregates of less than 4-micrometer crystals and amorphous silica as glassy scale less than 0.2 mm thick and as mounds of tubules with diameters less than 0.7 micrometers. The minute crystal sizes of calcite and gypsum from the field test are very different from the predominantly coarser calcite crystals (up to cm scale) in natural secondary-mineral deposits at the site. The complex micrometer-scale textures of the amorphous silica differ from the simple forms of opal spherules and coatings in the natural deposits, even though some natural spherules are as small as 1 micrometer. These differences suggest that the natural minerals, especially if they were of hydrothermal origin, may have developed coarser or simpler forms during subsequent episodes of dissolution and redeposition. The presence of gypsum among the test products and its absence from the natural secondary-mineral assemblage may indicate a higher degree of evaporation during the test than

Assessment of groundwater contamination by gypsum dissolution in San Luis Potosí (México) using geoelectrical characterization

Science.gov (United States)

Arango-Galvan, C.; Ramos-Leal, J. A.; Yáñez-Rodríguez, M. A.; Corbo-Camargo, F.

2017-12-01

The Cerritos and Río Verde aquifers in San Luis Potosí (central México) make up a very complex aquifer system that is seriously affected by the overexploitation and the high concentration of sulphates. Currently, it is partially closed for extraction causing a substantial decrease in per capita drinking water availability affecting to more than 50,000 inhabitants in the region. Therefore, a very comprehensive study has been proposed in order to evaluate not only the groundwater contamination distribution but also to better know the aquifer configuration and its main hydrogeological characteristics as well. These studies include a detailed geological reconnaissance, hydrogeochemical analyses and a geoelectrical characterization. The main goal is to assess the aquifer geometry and to identify the gypsum horizons causing the presence of higher concentrations of sulphates in drinking water. A total of 26 audiomagnetotelluric soundings were measured and modelled along profiles following a perpendicular direction to the NW regional trending. Two-dimensional resistivity models suggest the presence of a shallow conductive layer (C1) with resistivity values ranging from 10 to 20 Ohm.m. It is related to the upper aquifer with a very low exploitation potential. A less conductive horizon (C2; 50 Ohm.m) underlying the shallow aquifer could be related to a very fractured limestone horizon forming a confined aquifer in the middle of the valley. A very resistive layer (R1) is observed underlying C1 and C2 units. This strata shows higher resistivity values (>100 Ohm.m) and could be associated with a reefal limestone identified as El Abra Formation. Finally, a conductive layer (<100 Ohm.m) observed beneath this horizon could be related to the oldest stratigraphic unit outcropping on the region, the Guaxcamá Formation, a gypsum-enriched unit, that contributes to the presence of sulphates in the upper aquifers by dissolution processes.

Effect of alginate chemical disinfection on bacterial count over gypsum cast

OpenAIRE

Haralur, Satheesh B.; Al-Dowah, Omir S.; Gana, Naif S.; Al-Hytham, Abdullah

2012-01-01

PURPOSE To evaluate the efficacy of sodium hypochlorite (1 : 10) and iodophor disinfectants on alginate impressions along with their effect on the survived bacterium count on the gypsum cast. MATERIALS AND METHODS Four alginate impression on each dentate patients were made, of which Group I were not washed or disinfected, Group II impressions were merely washed with water, Group III were disinfected by spraying with sodium hypochlorite (1 : 10), Group IV were disinfected with iodophor (1 : 21...

Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors

Energy Technology Data Exchange (ETDEWEB)

Xu Qiyong [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); School of Environment and Energy, Shenzhen Graduate School of Peking University, 518055, (China); Townsend, Timothy, E-mail: ttown@ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Bitton, Gabriel [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States)

2011-07-15

Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H{sub 2}S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H{sub 2}S production in landfills results from biological activity, the concept of inhibiting H{sub 2}S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na{sub 2}MoO{sub 4}), ferric chloride (FeCl{sub 3}), and hydrated lime (Ca(OH){sub 2}) - were evaluated using flask and column experiments. All three agents inhibited H{sub 2}S generation, with Na{sub 2}MoO{sub 4} reducing H{sub 2}S generation by interrupting the biological sulfate reduction process and Ca(OH){sub 2} providing an unfavorable pH for biological growth. Although FeCl{sub 3} was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H{sub 2}S production in the column experiment was a reduction in pH. Application of both Na{sub 2}MoO{sub 4} and FeCl{sub 3} inhibited H{sub 2}S generation over a long period (over 180 days), but the impact of Ca(OH){sub 2} decreased with time as the alkalinity it contributed was neutralized by the generated H{sub 2}S. Practical application and potential environmental implications need additional exploration.

The Reclamation of Industrial Wastes Inclusive Sulphates by Sulphate-Reducing Bacteria

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Mária Kušnierová

2004-12-01

Full Text Available The objective of our study was to verify experimentally the possibility of using coal mine drainage and gypsum from the „stabilizate“ (the final product from the combustion desulphurisation as the source of sulphate for the cultivation of SRB with the prospect of: purging of mine waste waters inclusive sulphates, recycling of desulphurisation agent (limestone and production of elemental sulphur from hydrogen sulphide. The results confirmed the theoretical assumptions on the use of gypsum, which forms the substantial component of „stabilizate“, as the source of sulphate for sulphate-reducing bacteria, which produce hydrogen sulphide in the process of bacterial reduction of sulphates. They also showed the possibility of recycling the desulphurisation agent – limestone, as well as the realistic alternative of using „stabilizate“ in the production of elemental sulphur which still represents an important raw material needed in chemical, paper or other industries.

Populations of some molds in water-damaged homes may differ if the home was constructed with gypsum drywall compared to plaster

Science.gov (United States)

Starting in the 1940s, gypsum drywall began replacing plaster and lathe in the U.S. home construction industry. Our goal was to evaluate whether some mold populations differ in water- damaged homes primarily constructed with gypsum drywall compared to plaster. The dust samples fr...

Partial Characterisation of Bacteriocins Produced by Bacillus cereus Isolates from Milk and Milk Products

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Bojana Bogović Matijašić

2003-01-01

Full Text Available Thirty one (19.2 % out of 161 Bacillus cereus isolates from raw milk and milk products were found to produce proteinaceous substances which inhibit the growth of other B. cereus isolates. The detection of antibacterial activity depended on medium and method used. Bactericidal activity was detected in 23 (14 % or 19 (12 % of the tested strains on the triptic soya agar and brain-heart infusion with glucose, respectively, while 11 (7 % of the strains produced bactericidal substances on both media. Nineteen percent of isolates from raw milk and 20 % of isolates from milk products were found to produce bacteriocins. Four B. cereus isolates inhibited the growth of individual test strains belonging to B. licheniformis, B. subtilis, Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, Lactobacillus helveticus and L. casei species. The bacteriocins of four B. cereus isolates were studied in more detail. The production and activity of these substances were detected in stationary- phase of bacterial culture. Two of them were stable after heating at 60 °C, while only one was stable after heating at 75 °C for 15 minutes. All of them were active over a range of pH=3–10. The apparent molecular weights of four bacteriocins detected by SDS-PAGE electrophoresis were in the range of 1 to 8 kDa.

Phases, periphases, and interphases equilibrium by molecular modeling. I. Mass equilibrium by the semianalytical stochastic perturbations method and application to a solution between (120) gypsum faces

Science.gov (United States)

Pedesseau, Laurent; Jouanna, Paul

2004-12-01

The SASP (semianalytical stochastic perturbations) method is an original mixed macro-nano-approach dedicated to the mass equilibrium of multispecies phases, periphases, and interphases. This general method, applied here to the reflexive relation Ck⇔μk between the concentrations Ck and the chemical potentials μk of k species within a fluid in equilibrium, leads to the distribution of the particles at the atomic scale. The macroaspects of the method, based on analytical Taylor's developments of chemical potentials, are intimately mixed with the nanoaspects of molecular mechanics computations on stochastically perturbed states. This numerical approach, directly linked to definitions, is universal by comparison with current approaches, DLVO Derjaguin-Landau-Verwey-Overbeek, grand canonical Monte Carlo, etc., without any restriction on the number of species, concentrations, or boundary conditions. The determination of the relation Ck⇔μk implies in fact two problems: a direct problem Ck⇒μk and an inverse problem μk⇒Ck. Validation of the method is demonstrated in case studies A and B which treat, respectively, a direct problem and an inverse problem within a free saturated gypsum solution. The flexibility of the method is illustrated in case study C dealing with an inverse problem within a solution interphase, confined between two (120) gypsum faces, remaining in connection with a reference solution. This last inverse problem leads to the mass equilibrium of ions and water molecules within a 3 Å thick gypsum interface. The major unexpected observation is the repulsion of SO42- ions towards the reference solution and the attraction of Ca2+ ions from the reference solution, the concentration being 50 times higher within the interphase as compared to the free solution. The SASP method is today the unique approach able to tackle the simulation of the number and distribution of ions plus water molecules in such extreme confined conditions. This result is of prime

Nucleation and growth of the Naica giant gypsum crystals.

Science.gov (United States)

Otálora, Fermín; García-Ruiz, JuanMa

2014-04-07

The Cave of Giant Crystals in the Naica mine (Mexico) is one of the most amazing displays of mineral beauty ever created in nature. In addition to the colossal crystals of gypsum, which in some cases exceed eleven meters in length and one meter in thickness, the scenery fashioned by the crystalline beams that thrust through the darkness of the cave from floor to ceiling with a luster like moonlight is a unique example of harmony based on crystal symmetry. We review the crystallogenesis of this remarkable and challenging phenomenon of mineralization near equilibrium that can be used to teach the basics of nucleation and crystal growth.

Climatic control on the growth of gigantic gypsum crystals within hypogenic caves (Naica mine, Mexico)?

Science.gov (United States)

Garofalo, Paolo S.; Fricker, Mattias B.; Günther, Detlef; Forti, Paolo; Mercuri, Anna-Maria; Loreti, Mara; Capaccioni, Bruno

2010-01-01

Three hypogenic caves within the Naica mine of Mexico ( Cueva de los Cristales — CLC, Ojo de la Reina — OR, and Cueva de las Velas — CLV) host spectacular gypsum crystals up to 11 m in length. These caves are close to another shallow cave of the area ( Cueva de las Espadas — CLE), with which they cover a 160 m-deep vertical section of the local drainage basin. Similar to other hypogenic caves, all these caves lack a direct connection with the land surface and should be unrelated with climate. A record of multi-technique fluid inclusion data and pollen spectra from cave and mine gypsum indicates surprisingly that climatic changes occurring at Naica could have controlled fluid composition in these caves, and hence crystal growth. Microthermometry and LA-ICP-Mass Spectrometry of fluid inclusions indicate that the shallow, chemically peculiar, saline fluid (up to 7.7 eq. wt.%NaCl) of CLE could have formed from evaporation, during a dry and hot climatic period. The fluid of the deep caves was instead of low salinity (˜ 3.5 eq. wt.% NaCl) and chemically homogeneous, and was poorly affected by evaporation. We propose that mixing of these two fluids, generated at different depths of the Naica drainage basin, determined the stable supersaturation conditions for the gigantic gypsum crystals to grow. Fluid mixing was controlled by the hydraulic communication between CLE and the other deep caves, and must have taken place during cycles of warm-dry and fresh-wet climatic periods, which are known to have occurred in the region. Pollen grains from a 35 ka-old gypsum crystal of CLC corresponds to a fairly homogenous catchment basin made of a mixed broadleaf wet forest, which suggests precipitation during a fresh-wet climatic period and confirms our interpretation of the fluid inclusion data. The unusual combination of geological and geochemical factors of Naica suggests that other hypogenic caves found elsewhere may not host similar crystals. However, this work shows that

Growth of cowpea plants inoculated with Rhizobium in a saline-sodic soil after application of gypsum

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Angela Jessyka Pereira Brito Fontenele

Full Text Available Two experiments were carried out with the aim of evaluating the growth of cowpea cultivated in saline-sodic soils corrected with gypsum: one experiment in the laboratory, to identify the best level of gypsum for the correction of the saline-sodic soils of the state of Pernambuco, Brazil; and the other in a greenhouse, after correction of the soils. As the test plant, the cowpea cultivar pele de moça, inoculated with Rhizobium strain BR3267 was used. The experiments were arranged in a randomised block design in a 2 x 5 factorial arrangement, two soils and five levels of the gypsum requirement (GR, equivalent to 50, 100, 150, 200 and 250% of the GR of the soil, as determined by the Schoonover M-1 method, with five replications. The following were evaluated: electrical conductivity of the soil saturation extract (EC, soil exchangeable sodium and percentage of soil exchangeable sodium (ESP, number of nodules (NN, nodule dry weight (NDW, shoot dry weight (SDW, shoot height (PH and nitrogen concentration (N in the shoots. Application of 100% of the GR, followed by the enough water for leaching, was effective for the correction of soil sodicity. The application of increasing levels of soil GR resulted in an increase in the number of nodules, dry weight of the nodules and shoots, and the height and levels of N absorbed by the plants in soil S2. In soil S1, the use of levels of 200 and 250% of soil the GR caused a decrease in all the variables under study.

Composting and gypsum amendment of broiler litter to reduce nutrient leaching loss

Science.gov (United States)

Relative to fresh broiler litter, little is known about the dynamics of composted litter derived-nutrient in the ecosystem. In this study, the potential leaching losses of nutrients from compost relative to fresh broiler litter along with flue gas desulfurization (FGD gypsum), as a nutrient immobil...

Luminescence rigidochromism as a probe for the setting of gypsum plaster

International Nuclear Information System (INIS)

Kunkely, Horst; Vogler, Arnd

2008-01-01

The setting of gypsum plaster can be monitored by luminescence rigidochromism. The progress of the setting process which is accompanied by hardening is indicated by a blue shift of the phosphorescence of a suitable water soluble rhenium complex. This rigidity increase of the plaster/water mixture takes place in two phases. In the beginning the rigidity increase is rather large while in the second much longer phase it is relatively small. The addition of a plasticizer (or retarder) keeps the rigidity smaller in the beginning, but only slightly affects the final rigidity of the set plaster

Evolution characteristic of gypsum-salt rocks of the upper member of Oligocene Lower Ganchaigou Fm in the Shizigou area, western Qaidam Basin

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Dinghong Yi

2017-09-01

Full Text Available Over years of oil and gas exploration in the Qaidam Basin, reservoirs have been discovered in many layers. In the Shizigou area, western Qaidam Basin, the upper member of Oligocene Lower Ganchaigou Fm is an important target for oil and gas exploration, and gypsum-salt rocks are the high-quality caprocks for the preservation of oil and gas reservoirs in this area. For predicting oil and gas exploration direction and target in the western Qaidam Basin and providing guidance for its oil and gas exploration deployment, its depositional characteristics and environment of gypsum-salt rocks in this area were investigated based on the core observation, thin section identification, and analysis of grain size, sensitivity parameter ratios (Sr/Cu, Fe/Mn, (Fe + Al/(Ca + Mg, V/(V + Ni and Pr/Ph, pyrite content and inclusions. The following characteristics are identified. First, gypsum-salt rocks are mainly distributed in the depocenter of the lake basin and their thickness decreases towards the margin of the basin. They are laterally transformed into carbonate rocks or terrigenous clastic rocks. They are areally distributed in the shape of irregular ellipse. Second, gypsum-salt rocks are vertically developed mainly in the middle and upper parts of the upper member of Lower Ganchaigou Fm and they are interbedded with carbonate rocks or terrigenous clastic rocks. Their single layer thickness changes greatly, and there are many layers with good continuity. Third, Sand Group III to Group I in the upper member of Lower Ganchaigou Fm (inter-salt are of reductive water environment of semi-deep to deep lake facies due to their sedimentation in an arid and hot climate. It is concluded that gypsum-salt rocks of the upper member of Lower Ganchaigou Fm are distributed widely with great accumulative thickness in this area; and that they are originated from deep lake water by virtue of evaporation, concentration and crystallization in an arid and hot climate instead

Radioecology of and radiation dose from Dutch waste gypsum released into the environment

International Nuclear Information System (INIS)

Koster, H.W.; Weers, A.W. van; Netherlands Energy Research Foundation, Petten)

1985-11-01

The Dutch industries release 9 kinds of waste gypsum, 90% of the total quantity is phosphogypsum. Only waste gypsums from the phosphate industries show increased radioactivity, the strongest in phosphogypsum. All phosphogypsum, 2 Tg.a -1 , is disposed of into the Rhine at Rotterdam. This leads to an increase of radionuclides, from the U-238 chain, along the Dutch coast. The calculated increase of activity concentrations in sea food causes an increase of the individual radiation dose of maximal 150 μSv.a -1 and of the Dutch population dose of 170 manSv.a -1 . Stacking of the phosphogypsum would result in a dose increase of one order of magnitude lower. The need for environmental disposal or stacking of at least the fine and coarse fractions of the phosphogypsum, which are difficult to recycle, will remain. (Auth.)

Permeability of gypsum samples dehydrated in air

Science.gov (United States)

Milsch, Harald; Priegnitz, Mike; Blöcher, Guido

2011-09-01

We report on changes in rock permeability induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air (dry) for up to 800 h at ambient pressure and temperatures between 378 and 423 K. Subsequently, the reaction kinetics, so induced changes in porosity, and the concurrent evolution of sample permeability were constrained. Weighing the heated samples in predefined time intervals yielded the reaction progress where the stoichiometric mass balance indicated an ultimate and complete dehydration to anhydrite regardless of temperature. Porosity showed to continuously increase with reaction progress from approximately 2% to 30%, whilst the initial bulk volume remained unchanged. Within these limits permeability significantly increased with porosity by almost three orders of magnitude from approximately 7 × 10-19 m2 to 3 × 10-16 m2. We show that - when mechanical and hydraulic feedbacks can be excluded - permeability, reaction progress, and porosity are related unequivocally.

Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

Science.gov (United States)

Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

2013-01-01

We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. PMID:24957062

Potentially harmful secondary metabolites produced by indoor Chaetomium species on artificially and naturally contaminated building materials

DEFF Research Database (Denmark)

Dosen, Ina; Nielsen, Kristian Fog; Clausen, Geo

2017-01-01

, have been screened for, and thus detected in buildings. In this study, we used a liquid chromatography-high resolution mass spectrometry approach to screen both artificially and naturally infected building materials for all the Chaetomium metabolites described in the literature. Pure agar cultures were...... also investigated in order to establish differences between metabolite production in vitro and on building materials as well as comparison to non-indoor reference strains. On building materials six different chaetoglobosins were detected in total concentrations of up to 950 mg/m2 from C. globosum along...... with three different chaetoviridins/chaetomugilins in concentrations up to 200 mg/m2. Indoor Chaetomium spp. preferred wood-based materials over gypsum, both in terms of growth rate and metabolite production. Cochliodones were detected for the first time on all building materials infected by both C. globosum...

Screening and characterization of bacteriocins produced by some Strains of Lactobacillus spp isolated from Iranian Dairy products

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S Mirdamadi

2011-11-01

Full Text Available In this study, the inhibitory effects of bacteriocins of lactobacilli which were isolated from Iranian traditional dairy products was determined against known gram positive, gram negative and yeast by well diffusion technique. Among 8 isolates with higher capability of bacteriocin production, 2 isolates were selected for further investigations. The bacteriocins were purified by iso-propanol and ammonium sulfate precipitation following by dialysis and chromatography technique. The molecular weight of bacteriocins was determined as 45 to 66/2 KDa. by SDS-page electrophoresis. According to the results, the produced bacteriocins had more inhibition effect on Micrococcus luteus PTCC1169, Staphylococcus epidermidis PTCC1435 as well as Bacillus cereus PTCC1247 and with lesser degree of extent on Listeria monocytogenes PTCC 1301. Results also revealed that, Micrococcus luteus  was the most sensitive bacterium among indicator bacteria, while Candid albicans PTCC 5027 identified as the most resistance organism. This research showed that, bacteriocins produced by lactobacilli isolated from traditional dairy products have high potency to be used against microbial pathogens and could be applied as bio-preservative in food products.

Palaeoclimatic significance of gypsum pseudomorphs in the inner shelf sediments off Machalipatnam bay

Digital Repository Service at National Institute of Oceanography (India)

Rao, V.P.

Pseudo-gypsum crystals have been found in the coarse fraction of the sediments from the inner continental shelf off Machilipatnam Bay. They range in size from 3 to 7 mm are elongate and lenticular in shape. Bassanite and calcite are pseudomorphs...

Studies on quality, storeability, cooking and processing for products of agricultural and livestock produced by natural farming

Energy Technology Data Exchange (ETDEWEB)

Cho, Han Ok; Byun, Myung Woo; Yang, Jae Seung; Jo, Sung Ki; Go, Youn Mi [Korea Atomic Energy Research Institute, Seoul (Korea, Republic of); Lee, Heun Ja; Lee, Sung Hee [Ansung National University, Ansung (Korea, Republic of)

1997-12-01

The wholesomeness of agricultural and livestock products produced in contaminated natural environment and inactivated farmland are under apprehension. We have to produce foodstuff reliable high quality and wholesomeness in harmonizing with environmental condition and sustainable agriculture. All members of Korean Natural Farming Association are working at the self-managing natural farming field and has been developed steadily to village unit due to voluntary demanding and self-practicing more than 30 years. Agricultural and livestock products and its processed foods produced by member of Association are distributing in domestic and exporting to Japan and other country with recognition of its high quality and wholesomeness by consumer. In order to propagate the natural farming technology and to increase the consumption of its products and processed food in domestic and abroad, scientific approach and evaluation for their quality were carried out in field of chemical component and microbial activity of farmland(32 kinds), physico-chemical properties of cereals(7 kinds), fruits and vegetables(14 kinds) and meat processed foods (2 kinds). 51 refs., 29 tabs. (author)

Visualization of the structural changes in plywood and gypsum board during the growth of Chaetomium globosum and Stachybotrys chartarum

DEFF Research Database (Denmark)

Lewinska, Anna Malgorzata; Hoof, Jakob Blæsbjerg; Peuhkuri, Ruut H.

2016-01-01

of building materials such as plywood and gypsum wallboard. This study focuses on using micro-computed tomography (microCT) to investigate changes of the structure of plywood and gypsum wallboard during fungal degradation by S. chartarum and C. globosum. Changes in the materials as a result of dampness...... and fungal growth were determined by measuring porosity and pore shape via microCT. The results show that the composition of the building material influenced the level of penetration by fungi as shown by scanning electron microscopy (SEM). Plywood appeared to be the most affected, with the penetration...

Composition of gypsum from the Koběřice quarry (Czech Republic)

Czech Academy of Sciences Publication Activity Database

Konečný, Pavel; Plevová, Eva; Vaculíková, Lenka; Kožušníková, Alena; Peterková, J.; Hundáková, M.

2011-01-01

Roč. 8, č. 2 (2011), s. 145-156 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30860518 Keywords : gypsum * Kobeřice quarry * spectroscopy Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/abstracts/AGG/02_11/5_Konecny.pdf

Remediation of saline-sodic soil with flue gas desulfurization gypsum in a reclaimed tidal flat of southeast China.

Science.gov (United States)

Mao, Yumei; Li, Xiaping; Dick, Warren A; Chen, Liming

2016-07-01

Salinization and sodicity are obstacles for vegetation reconstruction of coastal tidal flat soils. A study was conducted with flue gas desulfurization (FGD)-gypsum applied at rates of 0, 15, 30, 45 and 60Mg/ha to remediate tidal flat soils of the Yangtze River estuary. Exchangeable sodium percentage (ESP), exchangeable sodium (ExNa), pH, soluble salt concentration, and composition of soluble salts were measured in 10cm increments from the surface to 30cm depth after 6 and 18months. The results indicated that the effect of FGD-gypsum is greatest in the 0-10cm mixing soil layer and 60Mg/ha was the optimal rate that can reduce the ESP to below 6% and decrease soil pH to neutral (7.0). The improvement effect was reached after 6months, and remained after 18months. The composition of soluble salts was transformed from sodic salt ions mainly containing Na(+), HCO3(-)+CO3(2-) and Cl(-) to neutral salt ions mainly containing Ca(2+) and SO4(2-). Non-halophyte plants were survived at 90%. The study demonstrates that the use of FGD-gypsum for remediating tidal flat soils is promising. Copyright © 2016. Published by Elsevier B.V.

Studies on the enzymes produced by Basidiomycetes. Part 1. The production of crude enzymes

Energy Technology Data Exchange (ETDEWEB)

Hong, J. S.; Kim, D.H.

1981-01-01

Cellulase, protease, and xylanase, formation by the basidiomycetes, Pleurotus ostreatus 301 and Lentinus edodes 3-1 in growth on rice straw medium were studied. Cultural conditions adequate for enzyme production and effects of various materials and inorganic salts added to the rice straw media were investigated. Lentinus edodes 3-1 was an excellent producer of cellulase and xylanase, and Pleurotus ostreatus 301 of protease. The optimum conditions for enzyme production were 30 degrees for cellulase production and at 25 degrees for xylanase and protease production, with 75% moisture content and initial pH of 5.0-6.0. The appropriate incubation times for enzyme production were 30 days and 35 days for Pleurotus ostreatus 301 and Lentinus edodes 3-1, respectively. Among the various materials added, defatted soybean, defatted rape seed, or defatted sesame were all effective in enzyme production but reduced mycelial growth. Rice bran was also effective, particularly at a 30% concentration. The addition of inorganic salts enhanced enzyme production. Among inorganic salts, the optimum concentration of CaCO3 was 5%, and that of CaSO4 was 2%.

Quorum sensing signals are produced by Aeromonas salmonicida and quorum sensing inhibitors can reduce production of a potential virulence factor

DEFF Research Database (Denmark)

Rasch, Maria; Kastbjerg, Vicky Gaedt; Bruhn, Jesper Bartholin

2007-01-01

Many pathogens control production of virulence factors by self-produced signals in a process called quorum sensing (QS). We demonstrate that acyl homoserine lactone (AHL) signals, which enable bacteria to express certain phenotypes in relation to cell density, are produced by a wide spectrum...... of Aeromonas salmonicida strains. All 31 typical strains were AHL producers as were 21 of 26 atypical strains, but on a strain population basis, production of virulence factors such as protease, lipase, A-layer or pigment did not correlate with the production and accumulation of AHLs in the growth medium...... of Aeromonas salmonicida. The most efficient compound N-(heptylsulfanylacetyl)-L-homoserine lactone (HepS-AHL), reduced protease production by a factor of 10. Five extracellular proteases were detected on gelatin-containing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) gels and 3...

Filler de grafito reciclado de EDM en pastas de yeso = EDM recycled graphite filler in gypsum pastes

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Nelson Flores

2017-08-01

Full Text Available El grafito puede obtenerse de forma natural o sintética, pero este último se ha utilizado en carreteras debido a su dureza, así como en placas de cerámica fina. Se demuestran las posibilidades de la adición del polvo de grafito isostático procedente del fresado de moldes fabricados por Electroerosión de Penetración (EDM en compuestos a base de yeso. Para ello se prepararon mezclas de yeso industrial con adiciones en porcentajes diferentes de grafito EDM para evaluar las propiedades físicas y mecánicas, caracterizando previamente ambos materiales. El yeso fue sustituido por grafito en cinco fracciones diferentes, 5, 10, 15, 20 y 25%, en peso, en la preparación de las mezclas. En la designación Y-0.7G-0 y Y-0.6G-0 de las series de probetas prismáticas de 40x40x160mm, la letra Y se refiere al yeso y G significa grafito (G-0 probetas patrón sin grafito, con relaciones agua/yeso (a/y 0,7 y 0,6. Después del análisis de los resultados obtenidos, se realizó unas nuevas series con la adición de plastificante y también con mayor cantidad de grafito, 25 a 50% en peso y otras relaciones a/y basadas en su trabajabilidad, para verificar la incidencia en la resistencia a flexión y compresión. Abstract Graphite can be obtained naturally or synthetically, but the latter has been used on roads because of its hardness, as well as in thin ceramic plates. The possibilities of the addition of the isostatic graphite powder from the milling of molds made by EDM in gypsum-based compounds are demonstrated. For this purpose mixtures of industrial gypsum with additions in different percentages of EDM graphite were prepared to evaluate the physical and mechanical properties, previously characterizing both materials. The gypsum was replaced by graphite in five different fractions, 5, 10, 15, 20 and 25% by weight, in the preparation of the mixtures. In the designation Y-0.7G-0 and Y-0.6G-0 of the series of prismatic specimens of 40x40x160mm, the letter Y

LYOPHILIZATION EFFECT ON PRODUCTIVITY OF BUTANOL-PRODUCING STRAINS

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O. O. Tigunova

2016-10-01

Full Text Available Investigation of lyophilization effect on the productivity of butanol-producing strains was the aim of our research. For this purpose we used butanol-producing strains; technical glycerol; biomass of switchgrass Panicum virgatum L. Lyophilization was performed using a lyophilization-drying. The effect of the protective medium on residual moisture of freezedrying cultures suspensions depending on the concentration of glucose and sucrose was studed. It was shown that the lowest residual moisture was attained by using glucose and sucrose in amount of 10% and if the samples of freeze-drying bacteria had been saved for one month at 4 οC the productivity did not decrease. As temperature preservation was increased the productivity of the cultures was gradually decreased and it was greatly reduced at 30 οC. So the protective medium composition was optimized for lyophilization of butanol-producing strains as follows: sucrose 10.0%; gelatin 10.0%; agar 0.02%. It was shown that the preservation of samples of freeze-drying bacteria for six months at a temperature of 4 οC did not affect the productivity of strains. It was found that cultures could use glycerol as a carbon source for butanol accumulation before lyophilization.

Production of bioethanol from fermented sugars of sugarcane bagasse produced by lignocellulolytic enzymes of Exiguobacterium sp. VSG-1.

Science.gov (United States)

Vijayalaxmi, S; Anu Appaiah, K A; Jayalakshmi, S K; Mulimani, V H; Sreeramulu, K

2013-09-01

Exiguobacterium sp. VSG-1 was isolated from the soil sample and characterized for the production of lignocellulolytic enzymes. Production of these enzymes by the strain VSG-1 was carried out using steam-exploded sugarcane bagasse (SCB) and found to secrete cellulase, pectinase, mannanase, xylanase, and tannase. The growth and enzyme production were found to be optimum at pH 9.0 and 37 °C. Upon steam explosion of SCB, the cellulose increased by 42 %, whereas hemicelluloses and lignin decreased by 40 and 62 %, respectively. Enzymatic hydrolysis of steam-exploded SCB yielded 640 g/l of total sugars. Fermentation of sugars produced from pretreated SCB was carried out by using Saccharomyces cerevisiae at pH 5.0 and 30 °C. The alcohol produced was calculated and found to be 62.24 g/l corresponding to 78 % of the theoretical yield of ethanol. Hence, the strain VSG-1 has an industrial importance for the production of fermentable sugars for biofuels.

New Blue Pigment Produced by Pantoea agglomerans and Its Production Characteristics at Various Temperatures ▿

OpenAIRE

Fujikawa, Hiroshi; Akimoto, Ryo

2010-01-01

A bacterium capable of producing a deep blue pigment was isolated from the environment and identified as Pantoea agglomerans. The pigment production characteristics of the bacterium under various conditions were studied. The optimal agar plate ingredients for pigment production by the bacterium were first studied: the optimal ingredients were 5 g/liter glucose, 10 g/liter tryptic soy broth, and 40 g/liter glycerol at pH 6.4. Bacterial cells grew on the agar plate during the incubation, while ...

Obtention of agricultural gypsum traced on 34 S (Ca34 SO4.2H2O), by chemical reaction between H234 SO4 and Ca(OH)2

International Nuclear Information System (INIS)

Rossete, Alessandra L.R.M.; Bendassolli, Jose A.; Ignoto, Raquel de Fatima; Batagello, Hugo Henrique

2002-01-01

The gypsum (CaSO 4 .2H 2 O) has double function in the soil: as source of calcium and sulfur and reducing agent of aluminum saturation. The sulfur for the plants has acting in the vital functions and it is proven fact increase of the S deficiency in Brazilian soils. The isotope tracer 34 S can elucidate important aspects in the sulfur cycle. The Ca 34 SO 4 .2H 2 O was obtained by chemical reaction between Ca(OH) 2 and H 2 34 SO 4 solution. The acid was obtained by chromatography ionic change, using cationic resin Dowex 50WX8 and Na 2 34 SO 4 solution. The reaction was realized under slow agitation. After the reaction, the precipitate was separated and dried in ventilated stove at 60 deg C temperature. The Mass of the Ca 34 SO 4 .2H 2 O produced was determined by method gravimetric. This way, a system contends resin 426 cm 3 , considering volume of 2.2 liters can be obtained a solution contends 44.2 g of H 2 34 SO 4 , theoretically could be produced 78.0 g of Ca 34 SO 4 .2H 2 O approximately. With results of the tests were verified that there was not total precipitation of the Ca 34 SO 4 .2H 2 O. Were produced 73.7± 0.6 g of Ca 34 SO 4 .2H 2 O representing average income 94.6±0.8 %. The purity of the produced CaSO 4 .2H 2 O was 98%. (author)

Influence of the gypsum dehydration temperature and alkali additives on the properties of anhydrite cement

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Leskeviciene V.

2010-01-01

Full Text Available While dehydrating gypsum with additives at the temperatures of 800°C and 900°C the influence of alkali additives on both the crystalline structure of anhydrite and properties of anhydrite binder was investigated. The industrial and household wastes including other lowcost materials were used as additives. Having heated them with gypsum the anhydrite with alkali activation properties was obtained. The properties of such substances were evaluated using the methods of chemical, diffractive X-ray scanning and scanning electron microscopy (SEM analyses. Some additives, e.g. 5 % ground glass waste, were found to increase crystal agglomerate formation of anhydrite binder, accelerate the hydration process of anhydrite and double the compressive strength of hydrated samples compared to samples without additives.

A saúde no contexto do polo gesseiro de Araripina-Pernambuco, Brasil Health in the context of the gypsum production area of the city of Araripina, State of Pernambuco, Brazil

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Marcilio Sandro de Medeiros

2010-06-01

Full Text Available O processo de deteriorização socioambiental do polo gesseiro de Pernambuco necessita ser mais bem conhecido. Este artigo objetivou estudar os fatores epidemiológicos que concorrem com a saúde das pessoas. Um estudo epidemiológico transversal foi realizado no período de 2001 a 2003, por meio da aplicação de um questionário fechado no distrito de Morais, município de Araripina, considerado uma das principais localidades de produção de gesso e artefatos. Uma amostra randomizada foi extraída a partir dos 2.486 habitantes, considerando-se como erro aceitável de 5% para o Intervalo de Confiança (IC de Katz de 95%. Quatrocentas e sessenta e duas pessoas foram entrevistadas e os problemas de saúde mais referidos foram: irritação dos olhos (42,92%, sangramento de nariz (37,39%, tosse (28,26%, cansaço (21,73%, irritação na pele (18,48%, falta de ar (16,26% e história de doença respiratória pregressa (16,34%, todos estatisticamente significantes. No geral, crianças (de 1 a 9 anos e idosos ( > 60 anos relataram mais sintomas respiratórios. A poeira de gesso dentro de casa apresentou-se como um importante indicador qualitativo na avaliação de seu impacto na saúde das pessoas. Nos domicílios avaliados, a presença de poeira de gesso mostrou-se mais prevalente com as queixas de irritação dos olhos (RP = 1,91, irritação na pele (RP = 1,79, cansaço (RP = 1,77 e tosse (RP = 1,70.The socio-environmental deterioration process of the gypsum production area of the State of Pernambuco, Northeastern Brazil, must be better known. We aimed at investigating the epidemiological factors that coexist with people's health. A cross-sectional epidemiological study was carried out between 2001 and 2003 by means of the administration of a closed questionnaire in the district of Morais, municipality of Araripina, considered as one of the main production areas of gypsum and artifacts. A random sample was extracted from the 2,486 inhabitants, and a

Flue-gas desulfurization gypsum effects on urea-degrading bacteria and ammonia volatilization from broiler litter.

Science.gov (United States)

Burt, Christopher D; Cabrera, Miguel L; Rothrock, Michael J; Kissel, D E

2017-08-01

A major concern of the broiler industry is the volatilization of ammonia (NH3) from the mixture of bedding material and broiler excretion that covers the floor of broiler houses. Gypsum has been proposed as a litter amendment to reduce NH3 volatilization, but reports of NH3 abatement vary among studies and the mechanism responsible for decreasing NH3 volatilization is not well understood. The goal of this study was to evaluate the effect of adding 20 or 40% flue-gas desulfurization gypsum (FGDG) to broiler litter on pH, electrical conductivity (EC), water potential, urea-degrading bacteria abundance, NH3 and carbon dioxide (CO2) evolution, and nitrogen (N) mineralization in several 21-d experiments. The addition of FGDG to broiler litter increased EC by 24 to 33% (P mineralization by 10 to 11% (P = 0.0001) as compared to litters not amended with FGDG. Furthermore, the addition of FGDG to broiler litter decreased NH3 volatilization by 18 to 28% (P litter pH values compared to un-amended litter (P litter with 20% FGDG can decrease NH3 volatilization and increase the fertlizer value of broiler litter. © 2017 Poultry Science Association Inc.

Produced water: Market and global trends - oil production - water production - choice of technology

International Nuclear Information System (INIS)

Robertson, Steve

2006-01-01

The presentation discusses various aspects of the world oil production, the energy demand, the future oil supply, the oil prices and the production growth. Some problems with produced water are also discussed as well as aspects of the market for produced water technology (tk)

Blackberry Vinegar Produced By Successive Acetification Cycles: Production, Characterization And Bioactivity Parameters

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Mário Antônio Alves da Cunha

Full Text Available ABSTRACT: Blackberry vinegar was produced in successive acetification cycles and content of total phenolics, anthocyanins and antioxidant activity were evaluated along the production. Firstly, blackberry wine was obtained in bench-scale bioreactor, being verified 0.39 g/g ethanol yield, 1.78 g/L.h volumetric productivity and 76% efficiency. After, three successive acetification cycles were conducted efficiently in grapia barrel with average acetic acid production of 51.6 g/L, 72.2 % acetic acid yield and 0.4 g/L.h volumetric productivity. Appreciable contents of polyphenolic compounds, anthocyanins and high antioxidant activity were observed in the raw material, wine and vinegar obtained in each cycle of acetic acid transformation. Acetic acid transformation led the small reduction of antioxidant activity compared to alcoholic fermentation, but the antioxidant potential was maintained along the cycles. The content of total phenolics and anthocyanins also suffered a reduction in step of acetification.

Thermal preparation effects on the x-ray diffractograms of compounds produced during flue gas desulfurization

International Nuclear Information System (INIS)

Wertz, D.L.; Burns, K.H.; Keeton, R.W.

1995-01-01

The diffractograms of syn-gypsum and of flue gas desulfurization products indicate that CaSO 4 · 2H 2 O is converted to other phase(s) when heated to 100 degrees C. Syn-hannebachite CaSO 3 ·0.5H 2 O is unaffected by similar thermal treatment. 6 refs., 3 figs

Production and Recovery of Aroma Compounds Produced by Solid-State Fermentation Using Different Adsorbents

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Adriane B. P. Medeiros

2006-01-01

Full Text Available Volatile compounds with fruity characteristics were produced by Ceratocystis fimbriata in two different bioreactors: columns (laboratory scale and horizontal drum (semi-pilot scale. Coffee husk was used as substrate for the production of volatile compounds by solid-state fermentation. The production of volatile compounds was significantly higher when horizontal drum bioreactor was used than when column bioreactors were used. These results showed that this model of bioreactor presents good perspectives for scale-up and application in an industrial production. Headspace analysis of the solid-state culture detected twelve compounds, among them: ethanol, acetaldehyde, ethyl acetate, ethyl propionate, and isoamyl acetate. Ethyl acetate was the predominant product in the headspace (28.55 µmol/L/g of initial dry matter. Activated carbon, Tenax-TA, and Amberlite XAD-2 were tested to perform the recovery of the compounds. The adsorbent columns were connected to the column-type bioreactor. All compounds present in the headspace of the columns were adsorbed in Amberlite XAD-2. With Tenax-TA, acetaldehyde was adsorbed in higher concentrations. However, the recovery found by using the activated carbon was very low.

Extended Producer Responsibility and Product Stewardship for Tobacco Product Waste.

Science.gov (United States)

Curtis, Clifton; Collins, Susan; Cunningham, Shea; Stigler, Paula; Novotny, Thomas E

2014-09-01

This paper reviews several environmental principles, including Extended Producer Responsibility (EPR), Product Stewardship (PS), the Polluter Pays Principle (PPP), and the Precautionary Principle, as they may apply to tobacco product waste (TPW). The review addresses specific criteria that apply in deciding whether a particular toxic product should adhere to these principles; presents three case studies of similar approaches to other toxic and/or environmentally harmful products; and describes 10 possible interventions or policy actions that may help prevent, reduce, and mitigate the effects of TPW. EPR promotes total lifecycle environmental improvements, placing economic, physical, and informational responsibilities onto the tobacco industry, while PS complements EPR, but with responsibility shared by all parties involved in the tobacco product lifecycle. Both principles focus on toxic source reduction, post-consumer take-back, and final disposal of consumer products. These principles when applied to TPW have the potential to substantially decrease the environmental and public health harms of cigarette butts and other TPW throughout the world. TPW is the most commonly littered item picked up during environmental, urban, and coastal cleanups globally.

Factors affecting the precipitation of pure calcium carbonate during the direct aqueous carbonation of flue gas desulfurization gypsum

International Nuclear Information System (INIS)

Song, Kyungsun; Jang, Young-Nam; Kim, Wonbaek; Lee, Myung Gyu; Shin, Dongbok; Bang, Jun-Hwan; Jeon, Chi Wan; Chae, Soo Chun

2014-01-01

The mineral carbonation of FGD (flue gas desulfurization) gypsum was carried out through CO 2 sorption into ammonia solution containing FGD gypsum. High-purity calcium carbonate was precipitated from DCC (dissolved calcium carbonate) solution which was extracted during the induction period. The factors affecting the preparation of pure calcium carbonate were examined under the following conditions: CO 2 flow rate (1–3 L/min), ammonia content (4–12%), and S/L (solid-to-liquid) ratio (5–300 g/L). X-Ray diffraction study revealed that the PCC (precipitated calcium carbonate) was round-shaped vaterite. The induction time for PCC decreased as the CO 2 flow rate increased. The maximum formation efficiency for pure PCC was seen to increase linearly with the ammonia content. The formation efficiency for pure PCC was the highest (90%) for S/L ratio of 5 g/L but it decreased as S/L ratio increased. On the other hand, S/L ratio didn't affect the maximum solubility limit of DCC. It is believed that the pure PCC would add an economic value to the FGD gypsum carbonation for industrial CO 2 sequestration. - Highlights: • Pure and white CaCO 3 was synthesized using induction period during direct carbonation of FGD gypsum. • Its formation efficiency was increased with ammonia content but decreased with solid-to-liquid ratio. • This method is expected to extend to other industrial CO 2 sequestration for the enhanced economic value of precipitated CaCO 3

Utilization of a by-product produced from oxidative desulfurization process over Cs-mesoporous silica catalysts.

Science.gov (United States)

Kim, Hyeonjoo; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Kim, Do Heui; Jeon, Jong-Ki

2011-02-01

We investigated the use of Cs-mesoporous silica catalysts to upgrade a by-product of oxidative desulfurization (ODS). Cs-mesoporous silica catalysts were characterized through N2 adsorption, XRD, CO2-temperature-programmed desorption, and XRF. Cs-mesoporous silica prepared by the direct incorporation method showed higher catalytic performance than a Cs/MCM-41 catalyst by impregnation method for the catalytic decomposition of sulfone compounds produced from ODS process.

Regional transport of a chemically distinctive dust: Gypsum from White Sands, New Mexico (USA)

Science.gov (United States)

White, Warren H.; Hyslop, Nicole P.; Trzepla, Krystyna; Yatkin, Sinan; Rarig, Randy S.; Gill, Thomas E.; Jin, Lixin

2015-03-01

The White Sands complex, a National Monument and adjoining Missile Range in southern New Mexico, occupies the dry bed of an ice-age lake where an active gypsum dunefield abuts erodible playa sediments. Aerosols entrained from White Sands are sometimes visible on satellite images as distinct, light-colored plumes crossing the Sacramento Mountains to the east and northeast. The IMPROVE network (Interagency Monitoring of PROtected Visual Environments) operates long-term aerosol samplers at two sites east of the Sacramento range. In recent years a spring pulse of sulfate aerosol has appeared at these sites, eclipsing the regional summer peak resulting from atmospheric reactions of sulfur dioxide emissions. A significant fraction of this spring sulfate is contributed by gypsum and other salts from White Sands, with much of the sulfur in coarse particles and concentrations of calcium and strontium above regional levels. The increase in these gypsiferous species coincides with a drought following a period of above-average precipitation. White Sands and the IMPROVE samplers together provide a natural laboratory: a climatically sensitive dust source that is both well characterized and chemically distinct from its surroundings, with a signature that remains identifiable at long-term observatories 100-200 km downwind.

18O and 34S in the Upper Bartonium gypsum deposits of the Paris basin

International Nuclear Information System (INIS)

Fontes, J.C.; Letolle, R.

1976-01-01

Isotopic analyses ( 18 O and 34 S) of the Eocene gypsum from the Paris basin show a range beyond the normal Tertiary marine values. The possibility of a reduction process during diagenesis is discussed. A hypothesis of continental origin by leaching of Permotriassic deposits is proposed for this formation on the basis of a comparison of the isotopic contents recorded from Germany and eastern France

Removal of Hg, As in FGD gypsum by different aqueous ammonia (amines) during CO2 sequestration.

Science.gov (United States)

Wenyi, Tan; Wenhui, Fan; Hongyi, Li; Zixin, Zhang; Yunkun, Zhu

2017-12-01

CO 2 sequestration by flue gas desulfurization gypsum (FGDG) has become a promising FGDG disposal technology due to simultaneous CO 2 emission reduction and FGDG conversion into calcium carbonate. In this paper, another merit of the novel technology, i.e., the removal of toxic elements (e.g., Hg and As) in FGDG, will be addressed for the first time. In three different aqueous ammonia (or amines) media, removal efficiencies of Hg and As in FGDG samples were evaluated during CO 2 sequestration. Higher than 90% and 20% removal efficiencies, respectively, for Hg and As are achieved at 40°C in aqueous ammonia media, but they decrease at elevated temperatures. Ammonia loss takes place at 80°C and pH varies greatly with temperatures in aqueous ammonia. This is disadvantageous for the formation of Hg-ammonia complexes and for the yield of carbonates, which are responsible for Hg or As re-adsorption. The sequential chemical extraction method suggests that the speciation changes of Hg are induced by FGDG carbonation, and that unstable Hg speciation in triethanolamine increases at elevated temperatures.

Optically stimulated luminescence dosimetry with gypsum wallboard (drywall)

International Nuclear Information System (INIS)

Thompson, J. W.; Burdette, K. E.; Inrig, E. L.; Dewitt, R.; Mistry, R.; Rink, W. J.; Boreham, D. R.

2010-01-01

Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d. (authors)

East Europe Report, Economic and Industrial Affairs, Long-Term Program for Production Quality

Science.gov (United States)

1984-05-29

increase the production of confectionery goods and snacks with a lower sugar content but enriched with natural juice and vegetable fillers, vegetable and...variety of con- struction materials and items by organizing the production of gasconcrete, extruded asbestos cement walls, gypsum board, heat, water

Developing biodiversity indicators on a stakeholders' opinions basis: the gypsum industry Key Performance Indicators framework.

Science.gov (United States)

Pitz, Carline; Mahy, Grégory; Vermeulen, Cédric; Marlet, Christine; Séleck, Maxime

2016-07-01

This study aims to establish a common Key Performance Indicators (KPIs) framework for reporting about the gypsum industry biodiversity at the European level. In order to integrate different opinions and to reach a consensus framework, an original participatory process approach has been developed among different stakeholder groups: Eurogypsum, European and regional authorities, university scientists, consulting offices, European and regional associations for the conservation of nature, and the extractive industry. The strategy is developed around four main steps: (1) building of a maximum set of indicators to be submitted to stakeholders based on the literature (Focus Group method); (2) evaluating the consensus about indicators through a policy Delphi survey aiming at the prioritization of indicator classes using the Analytic Hierarchy Process method (AHP) and of individual indicators; (3) testing acceptability and feasibility through analysis of Environmental Impact Assessments (EIAs) and visits to three European quarries; (4) Eurogypsum final decision and communication. The resulting framework contains a set of 11 indicators considered the most suitable for all the stakeholders. Our KPIs respond to European legislation and strategies for biodiversity. The framework aims at improving sustainability in quarries and at helping to manage biodiversity as well as to allow the creation of coherent reporting systems. The final goal is to allow for the definition of the actual biodiversity status of gypsum quarries and allow for enhancing it. The framework is adaptable to the local context of each gypsum quarry.

Characterization of bacteriocin produced by Lactobacillus plantarum ...

African Journals Online (AJOL)

Characterization of bacteriocin produced by Lactobacillus plantarum F1 and ... brevis OG1 isolated from Nigerian fermented food products, produced bacteriocins ... interest for food safety and may have future applications as food preservative.

Geomorphological Evidence of Plausible Water Activity and Evaporatic Deposition in Interdune Areas of the Gypsum-rich Olympia Undae Dune Field

Science.gov (United States)

Szynkiewicz, A.; Ewing, R. C.; Fishbaugh, K. E.; Bourke, M. C.; Bustos, D.; Pratt, L. M.

2009-03-01

New morphological features (e.g., cross-bedding strata, bright patches), revealed by HiRISE for the gypsum-rich Olympia Undae Dune Field, appear to indicate the change(s) in paleoenvironmental conditions likely controlled by climate fluctuations in the North Pole of Mars.

Potential of Soil Amendments (Biochar and Gypsum in increasing Water Use Efficiency of Abelmoschus esculentus L. Moench

Directory of Open Access Journals (Sweden)

Aniqa eBatool

2015-09-01

Full Text Available Water being an essential component for plant growth and development, its scarcity poses serious threat to crops around the world. Climate changes and global warming are increasing the temperature of earth hence becoming an ultimate cause of water scarcity. It is need of the day to use potential soil amendments that could increase the plants’ resistance under such situations. Biochar and gypsum were used in the present study to improve the water use efficiency and growth of Abelmoschus esculentus L. Moench (Lady’s Finger. A six weeks experiment was conducted under greenhouse conditions. Stress treatments were applied after thirty days of sowing. Plant height, leaf area, photosynthesis, transpiration rate, stomatal conductance and water use efficiency were determined weekly under stressed (60% field capacity and non-stressed (100% field capacity conditions. Stomatal conductance and transpiration rate decreased and reached near to zero in stressed plants. Stressed plants also showed resistance to water stress upto five weeks and gradually perished at sixth week. On the other hand, water use efficiency improved in stressed plants containing biochar and gypsum as compared to untreated plants. Biochar alone is a better strategy to promote plant growth and WUE specifically of Abelmoschus esculentus, compared to its application in combination with gypsum.

Microbial Volatile Organic Compound Emissions from Stachybotrys chartarum growing on Gypsum Wallboard and Ceiling tile

Science.gov (United States)

This study compared seven toxigenic strains of S. chartarum found in water-damaged buildings to characterize the microbial volatile organic compound (MVOC) emissions profile while growing on gypsum wallboard (W) and ceiling tile (C) coupons. The inoculated coupons with their sub...

The DWPF strategy for producing an acceptable product

International Nuclear Information System (INIS)

Goldston, W.T.; Plodinec, M.J.

1991-01-01

The Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) will convert the 130 million liters of high-level nuclear waste at SRS into stable borosilicate glass. Production of canistered waste forms by the DWPF is scheduled to begin well before submission of the license application for the first repository. The Department of Energy has defined waste acceptance specifications to ensure that DWPF canistered waste forms will be acceptable for eventual disposal. To ensure that canistered waste forms meet those specifications, a program is being carried out to qualify the waste form and those aspects of the production process which affect product quality. This program includes: Pre-production qualification testing of simulated and actual waste forms; Disciplined demonstrations of the ability to produce an acceptable product during startup testing; and Application of a rigorous product control program during production

Producing deuterium-enriched products

International Nuclear Information System (INIS)

1980-01-01

A method of producing an enriched deuterium product from a gaseous feed stream of mixed hydrogen and deuterium, comprises: (a) combining the feed stream with gaseous bromine to form a mixture of the feed stream and bromine and exposing the mixture to an electrical discharge effective to form deuterium bromide and hydrogen bromide with a ratio of D/H greater than the ratio of D/H in the feed stream; and (b) separating at least a portion of the hydrogen bromide and deuterium bromide from the mixture. (author)

Dimuons produced by antineutrinos

International Nuclear Information System (INIS)

Benvenuti, A.; Cline, D.; Ford, W.T.; Imlay, R.; Ling, T.Y.; Mann, A.K.; Orr, R.; Reeder, D.D.; Rubbia, C.; Stefanski, R.; Sulak, L.; Wanderer, P.

1975-01-01

In a run with a predominantly phi-bar beam we have observed seven dimuon events which show clearly that dimuons are produced by phi-bar as well as by phi. Using the signature of those events we tentatively identify twelve dimuon events from earlier runs as phi-bar-induced. The characteristics of the total sample support the explanation that dimuons arise from new hadron production

Production and characterization of biosurfactant produced by a novel Pseudomonas sp. 2B.

Science.gov (United States)

Aparna, A; Srinikethan, G; Smitha, H

2012-06-15

Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminated with petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri Ammonium Bromide (CTAB)-Methylene blue agar selection medium and the qualitative drop-collapse test. An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactant production. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, 2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluated for their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97 g/L) occurred at 96 h when the cells were grown on modified PPGAS medium containing 1% (v/v) molasses at 30 °C and 150 rpm. The cell free broth containing the biosurfactant could reduce the surface tension to 30.14 mN/m. The surface active compound showed emulsifying activity against a variety of hydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysis of the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which was composed of high percentages of lipid (∼65%, w/w) and carbohydrate (∼32%, w/w). Fourier transform infrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl and methoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyl-l-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C(10)-C(10)) was detected in abundance with the predominant congener monorhamnolipid (l-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate, Rha-C(10)-C(10)). The crude oil recovery studies using the biosurfactant produced by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and bioremediation. Copyright © 2012 Elsevier B.V. All rights reserved.

Physical and mechanical characterization of gypsum boards containing phase change materials for latent heat storage

Directory of Open Access Journals (Sweden)

Oliver-Ramírez, A.

2011-09-01

Full Text Available This article describes the design and manufacture of a gypsum board which, despite its 45 % wt content of phase change materials, meets the minimum physical and mechanical requirements laid down in the legislation on gypsum plasters (Spanish and European standard UNE EN 13279 and Spanish specifications for gypsum acceptance, RY 85. Under this design, a one-metre square, 1.5-cm thick board contains 4.75 kg of PCM, much more than in any prior drylining (the maximum attained to date is 3 kg per m². The mechanical and physical characteristics of this new composite were previously improved with two joint-action additives: polypropylene fibres and melamine formaldehyde as a dispersing agent. In the 20-30 ºC temperature range, a gypsum board 1.5 cm thick containing this percentage of PCMs can store five times more thermal energy than conventional plasterboard of the same thickness, and the same amount of energy as half-foot hollow brick masonry.

En esta investigación se ha diseñado y fabricado un panel de escayola que incorpora un 45% en peso de material de cambio de fase, manteniendo las propiedades físicas y mecánicas exigidas en la normativa de aplicación para yesos de construcción (UNE EN 13279 y referencias a la RY 85. Así, un panel de 1,0 m² y 1,5 cm de espesor, contiene 4,75 kg de PCM, cantidad muy superior a la conseguida hasta la fecha (3 kg/m2. Para ello se ha mejorado previamente sus prestaciones mecánicas y físicas mediante adiciones binarias: fibras de polipropileno y dispersión de melanina formaldehído. Este porcentaje es capaz de almacenar en 1,5 cm de espesor cinco veces la energía térmica de un panel de cartón yeso con el mismo espesor y la misma cantidad que una fábrica de 1/2 pie de ladrillo hueco, en el rango de temperaturas próximas a la de confort (20-30 ºC.

Reduction of radioactivity produced by nuclear explosives

Energy Technology Data Exchange (ETDEWEB)

Lessler, Richard M [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

1970-05-15

Four main sources contribute to the radioactivity produced by a nuclear explosive: 1. Fission products from the nuclear explosive, 2. Fusion products from the nuclear explosive, 3. Induced radioactivity in the nuclear explosive, 4. Induced radioactivity in the environment. This paper will summarize some of the work done at the Lawrence Radiation Laboratory at Livermore to reduce the radioactivity from these sources to levels acceptable for peaceful applications. Although it is theoretically possible to have no radioactivity produced by nuclear explosives, this goal has not been achieved.

Food producers' product development: With regard to the requirements of retail chains

DEFF Research Database (Denmark)

Skytte, Hans

of technology evolution'. This model has been extended by theories on organizational identity, organizational fields, plausibility, and construction of meaning. Founded on a grounded theory approach the model was subsequently used for analysing the cooperation between Danish food producers and retail chains......This study investigates how it is possible for food producers and retailers to strengthen their competitiveness by coordinating food producers' product development process and retailers' assortment building process. The theoretical outset is taken in Garud and Rappa's model 'Socio-cognitive model...... in four countries regarding trade in pork and pork-based products. The paper concludes with a number of recommendations directed at food producers....

Non-Invasive Rapid Harvest Time Determination of Oil-Producing Microalgae Cultivations for Biodiesel Production by Using Chlorophyll Fluorescence

Energy Technology Data Exchange (ETDEWEB)

Qiao, Yaqin [Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan (China); University of Chinese Academy of Sciences, Beijing (China); Rong, Junfeng [SINOPEC Research Institute of Petroleum Processing, Beijing (China); Chen, Hui; He, Chenliu; Wang, Qiang, E-mail: wangqiang@ihb.ac.cn [Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan (China)

2015-10-05

For the large-scale cultivation of microalgae for biodiesel production, one of the key problems is the determination of the optimum time for algal harvest when algae cells are saturated with neutral lipids. In this study, a method to determine the optimum harvest time in oil-producing microalgal cultivations by measuring the maximum photochemical efficiency of photosystem II, also called Fv/Fm, was established. When oil-producing Chlorella strains were cultivated and then treated with nitrogen starvation, it not only stimulated neutral lipid accumulation, but also affected the photosynthesis system, with the neutral lipid contents in all four algae strains – Chlorella sorokiniana C1, Chlorella sp. C2, C. sorokiniana C3, and C. sorokiniana C7 – correlating negatively with the Fv/Fm values. Thus, for the given oil-producing algae, in which a significant relationship between the neutral lipid content and Fv/Fm value under nutrient stress can be established, the optimum harvest time can be determined by measuring the value of Fv/Fm. It is hoped that this method can provide an efficient way to determine the harvest time rapidly and expediently in large-scale oil-producing microalgae cultivations for biodiesel production.

Inductive effect produced by a mixture of carbon source in the production of gibberellic acid by Gibberella fujikuroi.

Science.gov (United States)

Rios-Iribe, Erika Y; Flores-Cotera, Luis B; Chávira, Mario M González; González-Alatorre, Guillermo; Escamilla-Silva, Eleazar M

2011-06-01

Gibberellic acid has been known since 1954 but its effect on rice still remains very important in the agricultural world. Gibberellic acid (GA3) is the main secondary metabolite produced by the Gibberella fujikuroi fungus. This hormone is of great importance in agriculture and the brewing industry, due to its fast and strong effects at low concentrations (μg) on the processes of growth stimulation, flowering, stem elongation, and germination of seeds, among others. Plant promoters of growth production such as the gibberellins, especially the GA3 are a priority in obtaining better harvests in the agricultural area and by extension, improving the food industry. Three routes to obtaining GA3 have been reported: extraction from plants, chemical synthesis and microbial fermentation. The latter being the most common method used to produce GA3. In this investigation, glucose-corn oil mixture was used as a carbon source on the basis of 40 g of carbon in a 7 L stirred tank bioreactor. A pH of 3.5, 29°C, 600 min(-1) agitation and 1 vvm aeration were maintained and controlled with a biocontroller connected to the bioreactor, throughout the entire culture time. The carbon source mixture affected the fermentation time as well as the production of the GAs. The production of 380 mg GA3L(-1) after 288 h of fermentation was obtained when the glucose-corn oil mixture was employed contrasting the 136 mg GA3L(-1) at 264 h of culture when only glucose was used.

Induction of bacteriocin production by coculture is widespread among plantaricin-producing Lactobacillus plantarum strains with different regulatory operons.

Science.gov (United States)

Maldonado-Barragán, Antonio; Caballero-Guerrero, Belén; Lucena-Padrós, Helena; Ruiz-Barba, José Luis

2013-02-01

We describe the bacteriocin-production phenotype in a group of eight singular bacteriocinogenic Lactobacillus plantarum strains with three distinct genotypes regarding the plantaricin locus. Genotyping of these strains revealed the existence of two different plantaricin-production regulatory operons, plNC8-plNC8HK-plnD or plnABCD, involving three-component systems controlled each of them by a specific autoinducer peptide (AIP), i.e. PLNC8IF or PlnA. While all of the strains produced antimicrobial activity when growing on solid medium, most of them halted this production when cultured in broth, thus reflecting the functionality of regulatory mechanisms. Antimicrobial activity in broth cultures was re-established or enhanced when the specific AIP was added to the culture or by coculturing with specific bacterial strains. The latter trait appeared to be widespread in bacteriocinogenic L. plantarum strains independently of the regulatory system used to regulate bacteriocin production or the specific bacteriocins produced. The induction spectrum through coculture, i.e. the pattern of bacterial strains able to induce bacteriocin production, was characteristic of each individual L. plantarum strain. Also, the ability of some bacteria to induce bacteriocin production in L. plantarum by coculture appeared to be strain specific. The fact that induction of bacteriocin production by coculturing appeared to be a common feature in L. plantarum can be exploited accordingly to enhance the viability of this species in food and feed fermentations, as well as to contribute to probiotic functionality when colonising the gastrointestinal tract. Copyright © 2012 Elsevier Ltd. All rights reserved.

Leaching characteristics of trace elements in desulfurization gypsum from a coal-fired power plant

Energy Technology Data Exchange (ETDEWEB)

Liu, Y.K.; Zhuo, Y.Q.; Zhu, Z.W.; Chen, C.H. [Tsinghua Univ., Beijing (China). Inst. of Thermal Engineering

2013-07-01

The contents and leaching characteristics of Cr, Cd, As, Pb and Se in FGD gypsum from a 200 MW coal-fired power plant were investigated in this study. Experimental results revealed that: the leaching characteristics of As and Se were similar, both leaching rates were not obviously affected by pH but increased with increase of the liquid-solid ratio. Pb and Cr had similar leaching characteristics, their leaching rates were closely related with the pH of leaching solution and increased with the lowering of pH and both increased with the increasing of solid-liquid ratio. Along with the increase of the liquid-solid ratio, the leaching gradually achieved balance, and the balanced liquid-solid ratio was bigger when pH of leaching solution was lower. Cd content of leaching solution was below detect limit, and thus failed to get its leaching characteristics. The order of trace element content in leaching solution is Pb < Cr < As < Se, and the order of leaching rates is Cr < As < Pb < Se. BCR extraction procedure revealed that trace elements in FGD gypsum were mainly existed as available fraction and migration ability was stronger than that of trace elements in fly ash from coal-fired power plants.

Age and speleogenesis of epigenic gypsum caves in the northern Apennines (Italy)

Science.gov (United States)

Columbu, Andrea; Chiarini, Veronica; De Waele, Jo; Drysdale, Russell; Forti, Paolo; Hellstrom, John; Woodhead, Jon

2016-04-01

Triassic and Messinian gypsum beds host the majority of the caves in the eastern flank of the northern Apennines. To date, more than six hundreds voids have been mapped, including the longest known epigenic gypsum cave system in the world (Spipola-Acquafredda, ~11 km of tunnels) (De Waele et al., 2013). Superimposed caves are typically sub-horizontal (Klimchouk, 2000) and connected through vertical shafts, reflecting the palaeo base-level variations. When preserved, river terraces at the surface lie at the same palaeo altitude of the base level and horizontal cave passages. Notwithstanding the well-known geology of the area known (Vai and Martini, 2001), the age of these caves has been greatly underestimated in the past. Considering the rapid dissolution of the gypsum and uplifting of the area, the start of speleogenesis activity was considered to have occurred during the last glacial age. The age of karst voids can be only indirectly estimated by the dating of the infilling sediments. U-Th dating on carbonate speleothems provides high-precision and accurate ages (Hellstrom, 2003; Scholz and Hoffmann, 2008). We thus applied this methodology to 20 speleothems coming from 14 different caves belonging to the Monte Tondo, Spipola Acquafredda, Castelnuovo, Stella-Rio Basino and Brisighella systems. The results show that: i) caves were forming since at least ~300 ka; ii) the peak of speleogenesis was reached during relatively cold climate stages, when rivers formed terraces at the surface and aggradation caused paragenesis in the stable cave levels (Columbu et al., 2015). Besides the significant contribution to the understanding of the Apennines evaporite karst evolution, this study (and its further advancement) may also refine knowledge of the local vs regional uplifting rates and base-level variations since the late Pleistocene (Wegmann and Pazzaglia, 2009). References Columbu, A., De Waele, J., Forti, P., Montagna, P., Picotti, V., Pons-Branchu, E., Hellstrom, J

Reciclado de placas de yeso laminado aligeradas con residuos de poliuretano = Recycling of gypsum plasterboard lightened with polyurethane waste

Directory of Open Access Journals (Sweden)

Lourdes Alameda

2015-05-01

Full Text Available Este trabajo presenta los resultados de un proceso experimental de reutilización de residuos obtenidos de desechos de placas de yeso laminado elaboradas con residuos poliméricos de origen industrial (espuma de poliuretano y reforzadas con fibras de polipropileno, para la fabricación de nuevas placas de yeso laminado. Para ello, se expone la metodología de reciclado de placas prefabricadas buscando de esta forma aumentar el ciclo de vida del yeso y de los residuos de poliuretano empleados. Para ello se detalla el proceso de fabricación las nuevas placas así como su caracterización mediante ensayos físicos y mecánicos a través de ensayos normalizados para placas de yeso laminado (densidad aparente, resistencia a flexión, absorción total en agua y dureza superficial. Los resultados obtenidos indican que es posible reciclar este tipo de prefabricados de una manera sencilla. De la misma forma se ha demostrado que las nuevas placas fabricadas con el residuo recuperado, presentan un buen comportamiento mecánico, a la par que se reduce su capacidad de absorción de agua y se aumenta su dureza su superficial. Abstract This paper presents the results of an experimental process of reusing waste obtained from waste gypsum plasterboard made from polymeric industrial waste (polyurethane foam and polypropylene fibers whit the aim to manufacturer new gypsum plasterboards. Therefore, a methodology to recycle is presented to increase the life cycle of waste gypsum. The manufacturing process of the plates is detailed as well as their physical and mechanical characterization by means of standardized for gypsum plasterboard (bulk density, flexion strength, total water absorption and surface hardness. The results indicate that it is possible to recycle this type of prefabricated in a simple way. Likewise it has been demonstrated that new plates made with the residue reusing, have good mechanical strength, at the same time reduce the capacity of water

Investigations on the production of labelled organic compounds by recoil labelling with gamma,n-produced 11-C-atoms

International Nuclear Information System (INIS)

Wagenbach, U.

1981-01-01

''Hot'' 11 C atoms are produced from 12 C(γ,n) 11 C nuclear reactions by bremsstrahlung at the 65 MeV electron linear accelerator in Giessen. The relative retention in various C-atoms of the amino acid, methionine, is determined by splitting of the terminal C-atoms of the molecule and by independent determination of the content of 11 C in the isolated and derived fragments. The terminal groups (thiomethyl or carboxyl groups) each carry approx. 25% of the total retained radioactivity, the remaining 50% being spread over the three inner carbon atoms. The activation of alkylamines, crystallised as hydrochlorides, hydrofluorides, oxalates and sulphates, leads to similar yields of direct labelling from 5 to 15%. Amines activated in the liquid state show a retention of less than 5%. The yields for labelled synthetic products are between 10 and 15% for amino acids and are often higher for crystallised amines. Amines activated in the liquid state produced greater yields of synthesis products but at the same time an increase in the product range. The labelled synthesis products can be separated faster by suitable methods such as preparative HPLC and are then available for carrier-free studies in the life sciences. (orig./EF) [de

Characterization mixtures of thick gypsum with addition of treated waste from laminated plasterboards

Directory of Open Access Journals (Sweden)

Rodríguez-Orejón, A.

2014-06-01

Full Text Available nvironmental protection involves the reuse of construction and demolition waste. In order to improve recycling, waste from laminated plasterboards is used in the cement and laminated gypsum boards manufacture.This article analyzes the use of ground and burnt laminated plasterboard (BLG waste mixed with thick gypsum (TG. Physical-mechanical characterization of superficial hardness and mechanical strength has been performed on different batches of plaster powder materials with different BLG waste particle sizes to determine its suitability. Coarse particle sizes were preferred in order to reduce the waste treatment. From all the mixtures studied, the one with the best results was TG + 5% BLG1.25 which forms a material of higher superficial hardness and strength. The results obtained in the study have proved suitable products for building use (both as renders and as prefabricated elements enabling for a reduction in the consumption of natural resources.La protección del medio ambiente implica la reutilización de los residuos de construcción y demolición. Los residuos de placas de yeso laminado se utilizan en la fabricación de cemento y de placas de yeso laminado. En este artículo se ha estudiado la utilización deresiduos de placa de yeso laminado cocido (YLC mezclado con yeso grueso (YG, realizándose la caracterización físico-mecánica de dureza superficial y resistencias mecánicas, para determinar su idoneidad formando materiales de yeso en polvo con distintas granulometrías de residuos de (YLC, teniendo preferencia por granulometrías gruesas, que reducen el tratamiento del residuo. De las mezclas estudiadas la que mejores resultados ha ofrecido es YG + 5%YLC1,25 formando un material de mayor dureza superficial y resistencia. De los resultados obtenidos en el estudio se puede afirmar que se han conseguido productos aptos para su utilización en edificación posibilitando una reducción del consumo de recursos naturales.

Results from a first production of enhanced Silicon Sensor Test Structures produced by ITE Warsaw

Science.gov (United States)

Bergauer, T.; Dragicevic, M.; Frey, M.; Grabiec, P.; Grodner, M.; Hänsel, S.; Hartmann, F.; Hoffmann, K.-H.; Hrubec, J.; Krammer, M.; Kucharski, K.; Macchiolo, A.; Marczewski, J.

2009-01-01

Monitoring the manufacturing process of silicon sensors is essential to ensure stable quality of the produced detectors. During the CMS silicon sensor production we were utilising small Test Structures (TS) incorporated on the cut-away of the wafers to measure certain process-relevant parameters. Experience from the CMS production and quality assurance led to enhancements of these TS. Another important application of TS is the commissioning of new vendors. The measurements provide us with a good understanding of the capabilities of a vendor's process. A first batch of the new TS was produced at the Institute of Electron Technology in Warsaw Poland. We will first review the improvements to the original CMS test structures and then discuss a selection of important measurements performed on this first batch.

Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide

KAUST Repository

Hargis, Craig W.; Kirchheim, Ana Paula; Monteiro, Paulo J.M.; Gartner, Ellis M.

2013-01-01

Suspensions of synthetic ye'elimite (C4A3S̄) in a saturated gypsum (CS̄H2) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C 4A3S̄, 15% CS̄H2, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO4 2 -/OH-) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate. © 2013 Elsevier Ltd.

Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide

KAUST Repository

Hargis, Craig W.

2013-06-01

Suspensions of synthetic ye\\'elimite (C4A3S̄) in a saturated gypsum (CS̄H2) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C 4A3S̄, 15% CS̄H2, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO4 2 -/OH-) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate. © 2013 Elsevier Ltd.

Developments in commercially produced microbials at Biochem Products

Science.gov (United States)

John Lublinkhof; Douglas H. Ross

1985-01-01

Biochem Products is part of a large industrial and scientific family - the Solvay Group. Solvay, headquartered in Brussels, Belgium is a multinational company with 46,000 employees worldwide. In the U.S., our working partners include a large polymer manufacturer, a peroxygen producer and a leading poultry and animal health products company. Biochem Products is a...

Producing chicken eggs containing isoflavone as functional food due to feeding effect of soy sauce by-product

Science.gov (United States)

Mahfudz, L. D.; Sarjana, T. A.; Muryani, R.; Suthama, N.

2018-01-01

The present study was aimed to verify the impact of feeding soy sauce by-product in producing isoflavone-enriched chicken eggs as functional food. Experiment used 200 laying hens of 80-week old with average body weight of 1,932.75±189.50 g. Experimental diets were formulated using yellow corn, rice bran, soybean meal, fish meal, meat bone meal, poultry meal, premix, CaCO3, and soy sauce by-product (SSBP). A completely randomized design with 4 treatments and 5 replication (10 birds each), was assigned in this experiment. Inclusion levels of SSBP were the treatments, namely, none (T0), 10 (T1), 12.5 (T2), and 15.0% (T3). Parameters observed were colour, index, and weight of egg yolk, and isoflavone content. Analysis of variance was applied and continued to Duncan test at 5% probability. Results indicated that yolk colour index and weight were not affected by the treatments, but isoflavone content was significantly (P<0.05) increased by feeding SSBP. Egg yolk isoflavone in T2 (0.41 mg/g) and T3 (0.47 mg/g) were higher than those in T0 (0.31 mg/g) and T1 (0.35 mg/g). In conclusion, dietary inclusion of soy sauce by-product at higher level (12.5 and 15.0%) can produce isoflavone-enriched eggs as functional food.

Natural and human-induced sinkholes in gypsum terrain and associated environmental problems in NE Spain

Science.gov (United States)

Benito, G.; Del Campo, P. Pérez; Gutiérrez-Elorza, M.; Sancho, C.

1995-04-01

The central Ebro Basin comprises thick evaporite materials whose high solubility produces typically karstic landforms. The sinkhole morphology developed in the overlying alluvium has been studied using gravimetry and ground-penetrating radar (GPR) on stream terraces, as well as analyzing the evolution of sinkhole morphologies observed in aerial photographs taken in 1928, 1957, and 1985. The sinkhole morphologies give some idea of possible subsurface processes as well as an indication of the final mechanisms involve in sinkhole development. On stream terraces and cover pediments the most commonly encountered dolines are bowl-shaped in their morphology with both diffuse and scarped edges. In contrast, dolines developed in the gypsiferous silt infilled valleys have a funnel and well-shaped morphology. The diffuse-edged bowl-shaped dolines are developed through the progressive subsidence of the alluvial cover, due to washing down of alluvial particles through small voids and cracks into deeper subsurface caves, resulting in a decrease alluvial density. Future compaction of the alluvial cover will produce surface subsidences. This type of dolines are associated with negative gravity anomalies. In contrast, the scarped-edge dolines are formed by the sudden collapse of a cavity roof. The cavities and cracks formed in the gypsum karst may migrate to the surface through the alluvial deposits by piping, and they may subsequently collapse. In this instance, the cavities can be detected by both gravity and GPR anomalies where the voids are not deeper than 4 5 m from the surface. These processes forming sinkholes can be enhanced by man-induced changes in the groundwater hydrologic regime by both inflows, due to irrigation, ditch losses, or pipe leakages, and by outflows from pumping activities.

Quantification of ochratoxin A-producing molds in food products by SYBR Green and TaqMan real-time PCR methods

DEFF Research Database (Denmark)

Rodríguez, Alicia; Rodríguez, Mar; Luque, M. Isabel

2011-01-01

, usually reported in food products, were used as references. All strains were tested for OTA production by mycellar electrokinetic capillary electrophoresis (MECE) and high-pressure liquid chromatography-mass spectrometry (HPLC-MS). The ability of the optimized qPCR protocols to quantify OTA......Ochratoxin A (OTA) is a mycotoxin synthesized by a variety of different fungi, most of them from the genera Penicillium and Aspergillus. Early detection and quantification of OTA producing species is crucial to improve food safety. In the present work, two protocols of real-time qPCR based on SYBR......-producing molds was evaluated in different artificially inoculated foods. A good linear correlation was obtained over the range 1 x 104 to 10 conidia/g per reaction for all qPCR assays in the different food matrices (cooked and cured products and fruits). The detection limit in all inoculated foods ranged between...

Aplicação de gesso e calcário na recuperação de solos salino-sódicos do Estado de Pernambuco Application of gypsum and limestone in the reclamation of saline-sodic soils of the Pernambuco State

Directory of Open Access Journals (Sweden)

Maria de F. C. Barros

2005-09-01

Full Text Available Experimento em colunas de solo foi conduzido, objetivando-se avaliar o efeito da aplicação de gesso e gesso + calcário, na recuperação de solos salino-sódicos do Perímetro Irrigado de Custódia, PE. Os tratamentos foram dispostos em um delineamento em blocos casualizados, com arranjo fatorial de quatro solos, dois métodos de aplicação de gesso e gesso + calcário (aplicados na superfície e incorporados aos primeiros 5 cm da coluna de solo, duas combinações dos corretivos (100% de gesso + 0% de calcário e 80% de gesso + 20% de calcário, calculados com base na necessidade de gesso dos solos, e quatro faixas de granulometria de gesso (2,0-1,0, 1,0-0,5, 0,5-0,3 e An experiment was carried out in soil columns with the objective of evaluating the effect of application of gypsum and limestone on reclamation of the saline-sodic soils in the Irrigation district of Custódia, PE. The treatments were arranged in a randomized block design in a factorial scheme of four soils, two methods for applications of gypsum and gypsum plus limestone (applied on surface and incorporated into the first five cm of the soil column, two combinations of the chemical amendments (100% gypsum plus 0% limestone and 80% gypsum plus 20% limestone, calculated on the basis of gypsum requirement of soil and four granulometry gypsum strips (2.0-1.0; 1.0-0.5; 0.5-0.3 and < 0.3 mm with three replications. The gypsum amount determined by the method of Schoonover M-1, under laboratory conditions, shows to be adequate in the displacement of the exchangeable sodium of the soil exchange complex. The efficiency of the gypsum as well as the gypsum plus lime mixture in reclamation of the soils shows to be superior, when the amendments are incorporated into the first 5 cm of the soil columns. Among the gypsum granulometry, the finest fractions, (0.5-0.3 mm and < 0.3 mm, presented better performance in replacing the exchangeable sodium of the exchange complex.

Results from a first production of enhanced Silicon Sensor Test Structures produced by ITE Warsaw

Energy Technology Data Exchange (ETDEWEB)

Bergauer, T. [Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, 1050 Vienna (Austria); Dragicevic, M. [Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, 1050 Vienna (Austria)], E-mail: dragicevic@oeaw.ac.at; Frey, M. [Institut fuer Experimentelle Kernphysik (IEKP), Universitaet Karlsruhe (Thailand) (Germany); Grabiec, P.; Grodner, M. [Institute of Electron Technology (ITE), Warsaw (Poland); Haensel, S. [Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, 1050 Vienna (Austria); Hartmann, F.; Hoffmann, K.-H. [Institut fuer Experimentelle Kernphysik (IEKP), Universitaet Karlsruhe (Thailand) (Germany); Hrubec, J.; Krammer, M. [Institute of High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, 1050 Vienna (Austria); Kucharski, K. [Institute of Electron Technology (ITE), Warsaw (Poland); Macchiolo, A. [Max-Planck-Institut fuer Physik (MPI), Munich (Germany); Marczewski, J. [Institute of Electron Technology (ITE), Warsaw (Poland)

2009-01-01

Monitoring the manufacturing process of silicon sensors is essential to ensure stable quality of the produced detectors. During the CMS silicon sensor production we were utilising small Test Structures (TS) incorporated on the cut-away of the wafers to measure certain process-relevant parameters. Experience from the CMS production and quality assurance led to enhancements of these TS. Another important application of TS is the commissioning of new vendors. The measurements provide us with a good understanding of the capabilities of a vendor's process. A first batch of the new TS was produced at the Institute of Electron Technology in Warsaw Poland. We will first review the improvements to the original CMS test structures and then discuss a selection of important measurements performed on this first batch.

Two distinctive new species of Commicarpus (Nyctaginaceae) from gypsum outcrops in eastern Ethiopia

DEFF Research Database (Denmark)

Friis, Ib; Gilbert, Michael G.; Weber, Odile

2016-01-01

During field trips in 2013 and 2014, two distinctive plants belonging to the genus Commicarpus were collected in the Lele Hills, Bale Zone, eastern Ethiopia, on outcrops of sedimentary rock belonging to the Gorrahei Formation with high contents of gypsum. The plants are here described as two new...

Method of producing gaseous products using a downflow reactor

Science.gov (United States)

Cortright, Randy D; Rozmiarek, Robert T; Hornemann, Charles C

2014-09-16

Reactor systems and methods are provided for the catalytic conversion of liquid feedstocks to synthesis gases and other noncondensable gaseous products. The reactor systems include a heat exchange reactor configured to allow the liquid feedstock and gas product to flow concurrently in a downflow direction. The reactor systems and methods are particularly useful for producing hydrogen and light hydrocarbons from biomass-derived oxygenated hydrocarbons using aqueous phase reforming. The generated gases may find used as a fuel source for energy generation via PEM fuel cells, solid-oxide fuel cells, internal combustion engines, or gas turbine gensets, or used in other chemical processes to produce additional products. The gaseous products may also be collected for later use or distribution.

Gold nanoparticles produced in situ mediate bioelectricity and hydrogen production in a microbial fuel cell by quantized capacitance charging.

Science.gov (United States)

Kalathil, Shafeer; Lee, Jintae; Cho, Moo Hwan

2013-02-01

Oppan quantized style: By adding a gold precursor at its cathode, a microbial fuel cell (MFC) is demonstrated to form gold nanoparticles that can be used to simultaneously produce bioelectricity and hydrogen. By exploiting the quantized capacitance charging effect, the gold nanoparticles mediate the production of hydrogen without requiring an external power supply, while the MFC produces a stable power density. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-invasive rapid harvest time determination of oil-producing microalgae cultivations for bio-diesel production by using Chlorophyll fluorescence

Directory of Open Access Journals (Sweden)

Yaqin eQiao

2015-10-01

Full Text Available For the large-scale cultivation of microalgae for biodiesel production, one of the key problems is the determination of the optimum time for algal harvest when algae cells are saturated with neutral lipids. In this study, a method to determine the optimum harvest time in oil-producing microalgal cultivations by measuring the maximum photochemical efficiency of photosystem II (PSII, also called Fv/Fm, was established. When oil-producing Chlorella strains were cultivated and then treated with nitrogen starvation, it not only stimulated neutral lipid accumulation, but also affected the photosynthesis system, with the neutral lipid contents in all four algae strains – Chlorella sorokiniana C1, Chlorella sp. C2, C. sorokiniana C3, C. sorokiniana C7 – correlating negatively with the Fv/Fm values. Thus, for the given oil-producing algae, in which a significant relationship between the neutral lipid content and Fv/Fm value under nutrient stress can be established, the optimum harvest time can be determined by measuring the value of Fv/Fm. It is hoped that this method can provide an efficient way to determine the harvest time rapidly and expediently in large-scale oil-producing microalgae cultivations for biodiesel production.

Investigation of bioresistant dry building mixes modified by carbon nanotubes

OpenAIRE

Korolev Evgeniy Valer'evich; Erofeev Vladimir Trofimovich; Suraeva Ekaterina Nikolaevna

2015-01-01

Dry construction mixes are today a product of high technologies. Depending on the purpose and requirements to the properties it is easy to produce dry construction mixes with different compositions and operating indicators in plant conditions using the necessary modifying additives. Cement, gypsum and other mineral binders are used in the construction mixes. Different types of cement are more heavily used in dry construction mixes. Such dry mixes are believed to be more effective materials co...

The transport characteristics of {sup 238}U, {sup 232}Th, {sup 226}Ra, and {sup 40}K in the production cycle of phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Jung, Yoon Hee; Lim, Jong Myoung; Ji, Young Yong; Chung, Kun Ho; Kang, Mun Ja [Environmental Radioactivity Assessment Team, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2017-03-15

Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., 238U and 226Ra), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, 238U, 232Th, 226Ra, and 40K levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of 238U, 232Th, 226Ra, and 40K. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. The concentration ratios of 226Ra and 238U in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was 40K, and the median 40K activity was 8.972 Bq·g−1 and 1.496 Bq·g−1, respectively. For the 238U series, the activity of 238U and 226Ra was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Although the activity of 40K in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of 226Ra and 238U in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing.

Resposta da alfafa a fontes de fósforo associadas ao gesso e à calagem Alfalfa response to phosphorus sources associated to gypsum and liming

Directory of Open Access Journals (Sweden)

Patrícia Sarmento

2001-06-01

Full Text Available O fósforo é um dos nutriente mais importante na produção de alfafa nos solos brasileiros. Diversas fontes de P são disponíveis no mercado e o fosfato de Gafsa (FG é considerado tão eficiente como solúvel. A eficiência dos adubos fosfatados é afetada pela acidez do solo. O uso do gesso associado ao FG pode corrigir o perfil do solo em relação ao alumínio e diminuir a fixação do P no solo. Portanto, o objetivo deste trabalho foi avaliar num experimento em vasos a eficiência do superfosfato triplo (ST, do FG e do FG com gesso, aplicados antes e depois da calagem, nas doses de 50, 100 e 200 mg P dm-3. Foi utilizado um solo classificado como LATOSSOLO VERMELHO-AMARELO Alumínico. Foram efetuados três plantios de alfafa, realizando-se um corte no primeiro plantio e três cortes no terceiro. Com o ST obteve-se maior produção de matéria seca (MS (3,3 g/vaso do que com o FG (1,0 g/vaso no primeiro plantio. Mas no terceiro plantio ocorreu menor produção de MS com o uso do ST (2,4 g/vaso do que com o FG (6,0 g/vaso. O gesso com FG elevou a produção de MS (7,0 g/vaso em relação ao FG (3,7 g/vaso no terceiro plantio. A aplicação do ST depois da calagem aumentou a produção de MS (5,0 g/vaso comparado a aplicação antes da calagem (3,7 g/vaso, no primeiro plantio. Não houve efeito do momento de calagem para o FG com ou sem gesso.Phosphorus is one of the most important nutrients in alfalfa production in Brazilian soils. Several P sources are available in the market and the Gafsa phosphate (GP is considered as efficient and soluble. The efficiency of phosphate fertilizers is affected by soil acidity. The use of GP associated to gypsum can aliviate Al toxicity and reduce soil phosphorus fixation. Therefore, this study was curried out in a glasshouse experiment, aiming to evaluate the efficiency of the triple superphosphate (TS and GP and GP with gypsum, applied before and after liming at the rates of 50; 100 and 200 mg P dm-3. The

Corrosion behaviour of metallic and non-metallic materials in various media in the Anhydrite and Gypsum Mine Felsenau/AG

International Nuclear Information System (INIS)

Laske, D.; Wiedemann, K.H.

1983-10-01

The final underground disposal of radioactive wastes necessitates container materials with a good long-term resistance against corrosion from both external agents and the solidification matrix inside. For low- and medium-level active waste, repositories in anhydrite sites, among others, are under consideration. Sheet and plate samples from 14 metallic and 8 non-metallic materials have been tested for 5 years in a tunnel in the Anhydrite and Gypsum Mine Felsenau/AG for their corrosion resistance in the tunnel atmosphere, anhydrite powder, gypsum powder, gypsum, and cement. From the metallic materials tested, only chromium-nickel steel is corrosion resistant to all the media present. Zinc plated and tin plated iron sheet as well as aluminium and aluminium alloys are corrosion resistant only in the atmosphere of the tunnel, and lead plated iron sheet is resistant also in cement. Aluminium is dissolved in cement. Uncovered iron sheet undergoes severe corrosion. The non-metallic coatings tested (lacquer, stove lacquer, or synthetic resins) partially flake off already after one year's testing and are therefore not appropriate for iron sheet corrosion protection. No influence of the different media has been observed after 5 years on the 8 plastic materials tested (6 without, and 2 with glass fiber reinforcement). (author)

Seepage Analysis of Upper Gotvand Dam Concerning Gypsum Karstification (2D and 3D Approaches)

DEFF Research Database (Denmark)

Sadrekarimi, Jamshid; Kiyani, Majid; Fakhri, Behnam

2011-01-01

Upper Gotvand Dam is constructed on the Karun River at the south west of Iran. In this paper, 2D and 3D models of the dam together with the foundation and abutments were established, and several seepage analyses were carried out. Then, the gypsum veins that are scattered throughout the foundation...

Value addition to locally produced soybean in Ghana: production of ...

African Journals Online (AJOL)

Ghana produces about 50,000 metric tons of soy beans per annum, of which only about 15 metric tons are utilized. One aspect of utilizing the beans is in the production of soy sauce, a product whose demand is on the increase due to changing food habits of the Ghanaian society. A preliminary attempt to produce soy sauce ...

Source of sulphur in the Ebro Basin (Northern Spain). Tertiary nonmarine evaporite deposits as evidenced by sulphur isotopes

International Nuclear Information System (INIS)

Birnbaum, S.J.; Coleman, D.

1979-01-01

The Ebro Basin is an intermontane basin, located in northern Spain, filled with Tertiary (largely Oligocene and Miocene) elastic and chemical deposits. Sulphur isotopes are utilized to determine the source of sulphur in the sulphate deposits (predominantly gypsum with accessory thenardite, mirabolite and epsomite). Data obtained from Tertiary gypsum rocks produce a range of delta 34 S values from +9.16% to + 14.02% with a mean of +13.61%. Data obtained from Triassic gypsum rocks (in source area) produce a range from +13.73% to +15.14%, with a mean of +14.66%. Values for Tertiary marine water range from +18% to +24%. These data indicate a nonmarine origin for sulpur within the Tertiary sulphate rocks. The contribution of Triassic sulphur to the groundwater system, plus varying degrees of dilution by isotopically lighter (atmospheric and sulphide) sulphur, best explains the isotopic ratios observed in the Tertiary Basin deposits. (Auth.)

Inflammatory potential of low doses of airborne fungi from fungal infested damp and dry gypsum boards

DEFF Research Database (Denmark)

Knudsen, Sofie Marie; Gunnarsen, Lars Bo; Madsen, Anne Mette

2017-01-01

chrysogenum. Bacillus infantis and Paenibacillus sp. were found on the gypsum boards, but not recovered in the aerosols. A significant correlation was found between the TIP of diluted and undiluted samples of fungal aerosols. However, diluted samples had a higher TIP than undiluted samples, and no significant...

Utilization of bacteriocin-producing bacteria in dairy products

Directory of Open Access Journals (Sweden)

Matěj Patrovský

2016-07-01

Full Text Available Lactic acid bacteria have been used since ancient times for food preparation and for bio-conservation by fermentation. Selected strains are capable of producing antimicrobial peptides - bacteriocins, which can be natural preservatives, especially in products with short shelf lives. The present study is focused on inhibitory effects of the bacteriocin-producing bacteria strains Enterococcus faecium, Pediococccus acidilactici and Lactobacillus plantarum against Listeria innocua as an indicator microorganism. Freeze-dried preparations of bacterial strains producing particular bacteriocins were tested by agar well-diffusion assay and by the traditional spread plate method. Plantaricin exhibited the highest anti-listerial effect among the tested bacteriocins. Pediocin also demonstrated a distinct inhibitory effect, but enterocin appeared to be heat labile and its efficiency was also suppressed under cold storage conditions. Plantaricin reduced Listeria innocua counts by 1 log in dairy spread made from cheese and quark. The formation of bacteriocins by various Lactobacillus plantarum strains were substantially influenced by the cultivation conditions of the mother culture and by the microbial preparation process before freeze-drying. Bacteriocins introduced into foodstuffs via protective cultures in situ offer new perspectives on enhancing food quality and safety.

Production and partial characterization of keratinase produced by a ...

African Journals Online (AJOL)

SERVER

2008-02-05

Feb 5, 2008 ... produced by a microorganism isolated from poultry processing plant wastewater. Daniel M. T. Tapia* and ... A number of keratinolytic microorganisms have been reported, including some species of .... were variable during cultivation in different feather meals. According to Sangali and Brandelli (2000), this ...

Delivering Mass-Produced Bespoke and Appealing Products

Science.gov (United States)

Childs, Thomas Hc; Dalgarno, Kenneth W.; McKay, Alison

The bottleneck in introducing successful new products quickly to market is moving from factory floor manufacturing to the product design process and interfaces between designers, manufacturers and users. ‘Quality’, for products that contact people, has moved beyond functionality and usability to satisfying people’s subjective and emotional lifestyle needs. Affective (kansei) engineering design offers approaches that can be used to bring the emotional responses of consumers into the design process. In parallel, mass customisation promises the delivery of mass-produced bespoke products to individual users. Together, affective engineering and mass customisation are having a dramatic impact on the ways in which designers, engineers and manufacturers interact with each other. The challenge for leading edge manufacture is to create new product opportunities through integration of and new developments in technology, systems and design.

Manufacturing of mortars and concretes non-traditionals, by Portland cement, metakaoline and gypsum (15.05%

Directory of Open Access Journals (Sweden)

Talero, R.

1999-12-01

Full Text Available In a thorough previous research (1, it appeared that creation, evolution and development of the values of compressive mechanical strength (CS and flexural strength (FS, measured in specimens 1x1x6cm of mortar type ASTM C 452-68 (2, manufactured by ordinary Portland cement P-1 (14.11% C₃A or PY-6 (0.00% C₃A, metakaolin and gypsum (CaSO₄∙2H₂O -or ternary cements, CT-, were similar to the ones commonly developed in mortars and concretes of OPC. This paper sets up the experimental results obtained from non-traditional mortars and concretes prepared with such ternary cements -TC-, being the portland cement/metakaolin mass ratio, as follows: 80/20, 70/30 and 60/40. Finally, the behaviour of these cements against gypsum attack, has been also determined, using the following parameters: increase in length (ΔL%, compressive, CS, and flexural, FS, strengths, and ultrasound energy, UE. Experimental results obtained from these non-traditional mortars and concretes, show an increase in length (ΔL, in CS and FS, and in UE values, when there is addition of metakaolin.

En una exhaustiva investigación anterior (1, se pudo comprobar que la creación, evolución y desarrollo de los valores de resistencias mecánicas a compresión, RMC, y flexotracción, RMF, proporcionados por probetas de 1x1x6 cm, de mortero 1:2,75, selenitoso tipo ASTM C 452-68 (2 -que habían sido preparadas con arena de Ottawa, cemento portland, P-1 (14,11% C₃A o PY- 6 (0,00% C₃A, metacaolín y yeso (CaSO₄∙2H₂O-, fue semejante a la que, comúnmente, desarrollan los morteros y hormigones tradicionales de cemento portland. En el presente trabajo se exponen los resultados experimentales obtenidos de morteros y hormigones no tradicionales, preparados con dichos cementos ternarios, CT, siendo las proporciones porcentuales en masa ensayadas, cemento portland/metacaolín, las siguientes: 80/20, 70

Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur.

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-06-01

More than 170 wet scrubber systems applied, to 72,000 MW of U.S., coal-fired, utility boilers are in operation or under construction. In these systems, the sulfur dioxide removed from the boiler flue gas is permanently bound to a sorbent material, such as lime or limestone. The sulfated sorbent must be disposed of as a waste product or, in some cases, sold as a byproduct (e.g. gypsum). Due to the abundance and low cost of naturally occurring gypsum, and the costs associated with producing an industrial quality product, less than 7% of these scrubbers are configured to produce usable gypsum (and only 1% of all units actually sell the byproduct). The disposal of solid waste from each of these scrubbers requires a landfill area of approximately 200 to 400 acres. In the U.S., a total of 19 million tons of disposable FGD byproduct are produced, transported and disposed of in landfills annually. The use of regenerable sorbent technologies has the potential to reduce or eliminate solid waste production, transportation and disposal. In a regenerable sorbent system, the sulfur dioxide in the boiler flue gas is removed by the sorbent in an adsorber. The S0{sub 2}s subsequently released, in higher concentration, in a regenerator. All regenerable systems produce an off-gas stream from the regenerator that must be processed further in order to obtain a salable byproduct, such as elemental sulfur, sulfuric acid or liquid S0{sub 2}.

Characterization of aerosols produced by surgical procedures

Energy Technology Data Exchange (ETDEWEB)

Yeh, H.C.; Muggenburg, B.A.; Lundgren, D.L.; Guilmette, R.A.; Snipes, M.B.; Jones, R.K. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States); Turner, R.S. [Lovelace Health Systems, Albuquerque, NM (United States)

1994-07-01

In many surgeries, especially orthopedic procedures, power tools such as saws and drills are used. These tools may produce aerosolized blood and other biological material from bone and soft tissues. Surgical lasers and electrocautery tools can also produce aerosols when tissues are vaporized and condensed. Studies have been reported in the literature concerning production of aerosols during surgery, and some of these aerosols may contain infectious material. Garden et al. (1988) reported the presence of papilloma virus DNA in the fumes produced from laser surgery, but the infectivity of the aerosol was not assessed. Moon and Nininger (1989) measured the size distribution and production rate of emissions from laser surgery and found that particles were generally less than 0.5 {mu}m diameter. More recently there has been concern expressed over the production of aerosolized blood during surgical procedures that require power tools. In an in vitro study, the production of an aerosol containing the human immunodeficiency virus (HIV) was reported when power tools were used to cut tissues with blood infected with HIV. Another study measured the size distribution of blood aerosols produced by surgical power tools and found blood-containing particles in a number of size ranges. Health care workers are anxious and concerned about whether surgically produced aerosols are inspirable and can contain viable pathogens such as HIV. Other pathogens such as hepatitis B virus (HBV) are also of concern. The Occupational Safety and Health funded a project at the National Institute for Inhalation Toxicology Research Institute to assess the extent of aerosolization of blood and other tissues during surgical procedures. This document reports details of the experimental and sampling approach, methods, analyses, and results on potential production of blood-associated aerosols from surgical procedures in the laboratory and in the hospital surgical suite.

Silicon nanoparticles produced by spark discharge

International Nuclear Information System (INIS)

Vons, Vincent A.; Smet, Louis C. P. M. de; Munao, David; Evirgen, Alper; Kelder, Erik M.; Schmidt-Ott, Andreas

2011-01-01

On the example of silicon, the production of nanoparticles using spark discharge is shown to be feasible for semiconductors. The discharge circuit is modelled as a damped oscillator circuit. This analysis reveals that the electrode resistance should be kept low enough to limit energy loss by Joule heating and to enable effective nanoparticle production. The use of doped electrodes results in a thousand-fold increase in the mass production rate as compared to intrinsic silicon. Pure and oxidised uniformly sized silicon nanoparticles with a primary particle diameter of 3–5 nm are produced. It is shown that the colour of the particles can be used as a good indicator of the oxidation state. If oxygen and water are banned from the spark generation system by (a) gas purification, (b) outgassing and (c) by initially using the particles produced as getters, unoxidised Si particles are obtained. They exhibit pyrophoric behaviour. This continuous nanoparticle preparation method can be combined with other processing techniques, including surface functionalization or the immediate impaction of freshly prepared nanoparticles onto a substrate for applications in the field of batteries, hydrogen storage or sensors.

Unraveling the mystery of commercial cultivation of Agaricus bisporus : plant biomass utilization and its effect on mushroom production

NARCIS (Netherlands)

Patyshakuliyeva, A.

2015-01-01

Agaricus bisporus, the white button mushroom, is economically the most important mushroom cultivated worldwide. Growth of A. bisporus needs a substrate produced by the composting of animal manure, wheat straw, gypsum, water and different additives. Therefore lignocellulose which is a complex mixture

Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions.

Science.gov (United States)

Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N Suman; Tadi, Durga Prasad

2016-01-01

This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two criteria. All the samples were evaluated, and the data obtained were analyzed by a two-way analysis of variance (ANOVA) and Pearson's Chi-square tests. When surface detail reproduction was evaluated with modification of ADA specification no. 19, both the groups under the two conditions showed no significant difference statistically. When evaluated macroscopically both the groups showed statistically significant difference. Results for dimensional stability showed that the deviation from standard was significant among the two groups, where Aquasil group showed significantly more deviation compared to Impregum group (P < 0.001). Two conditions also showed significant difference, with moist conditions showing significantly more deviation compared to dry condition (P < 0.001). The results of gypsum compatibility when evaluated with modification of ADA specification no. 19 and by giving grades to the casts for both the groups and under two conditions showed no significant difference statistically. Regarding dimensional stability, both impregum and aquasil performed better in dry condition than in moist; impregum performed better than aquasil in both the conditions. When tested for surface detail reproduction according to ADA specification, under dry and moist conditions both of them performed almost equally. When tested according to macroscopic evaluation, impregum and aquasil performed significantly better in dry condition compared to moist condition. In dry condition, both the materials performed almost equally. In

The transport characteristics of "2"3"8U, "2"3"2Th, "2"2"6Ra, and "4"0K in the production cycle of phosphate rock

International Nuclear Information System (INIS)

Jung, Yoon Hee; Lim, Jong Myoung; Ji, Young Yong; Chung, Kun Ho; Kang, Mun Ja

2017-01-01

Phosphate rock and its by-product are widely used in various industries to produce phosphoric acid, gypsum, gypsum board, and fertilizer. Owing to its high level of natural radioactive nuclides (e.g., 238U and 226Ra), the radiological safety of workers who work with phosphate rock should be systematically managed. In this study, 238U, 232Th, 226Ra, and 40K levels were measured to analyze the transport characteristics of these radionuclides in the production cycle of phosphate rock. Energy dispersive X-ray fluorescence and gamma spectrometry were used to determine the activity of 238U, 232Th, 226Ra, and 40K. To evaluate the extent of secular disequilibrium, the analytical results were compared using statistical methods. Finally, the distribution of radioactivity across different stages of the phosphate rock production cycle was evaluated. The concentration ratios of 226Ra and 238U in phosphate rock were close to 1.0, while those found in gypsum and fertilizer were extremely different, reflecting disequilibrium after the chemical reaction process. The nuclide with the highest activity level in the production cycle of phosphate rock was 40K, and the median 40K activity was 8.972 Bq·g−1 and 1.496 Bq·g−1, respectively. For the 238U series, the activity of 238U and 226Ra was greatest in phosphate rock, and the distribution of activity values clearly showed the transport characteristics of the radionuclides, both for the byproducts of the decay sequences and for their final products. Although the activity of 40K in k-related fertilizer was relatively high, it made a relatively low contribution to the total radiological effect. However, the activity levels of 226Ra and 238U in phosphate rock were found to be relatively high, near the upper end of the acceptable limits. Therefore, it is necessary to systematically manage the radiological safety of workers engaged in phosphate rock processing

Transmission factors for neutrons produced by radioisotopes production used in PET

International Nuclear Information System (INIS)

Hernandez G, D.; Cruzate, J.A.

1996-01-01

The dose transmission factor for normal concrete and the neutrons produced in the 18 O(p,n) 18 F and 13 C(p,n) 13 N reactions are presented in this paper. These transmission factors permit to simplify the calculation of the necessary accelerator shielding to be used in the radioisotope production for positron emission tomography. The energy distributions of the neutrons resulting from the irradiation of thick targets, with 10 to 13 MeV protons, were determined using the thin target cross sections, the energy loss per path length and the energy balance of the reaction (Q-equation). The one dimensional discrete ordinate transport code ANISN and the conversion coefficients from fluence to dose, presented in the ICRP Publication 51 were employed to obtain the transmission factors. (authors). 12 refs., 3 figs., 2 tabs

Biofilm production by clinical isolates of Pseudomonas aeruginosa and structural changes in LasR protein of isolates non biofilm-producing

Directory of Open Access Journals (Sweden)

Jailton Lobo da Costa Lima

2018-03-01

Full Text Available Introduction: Biofilm production is an important mechanism for the survival of Pseudomonas aeruginosa and its relationship with antimicrobial resistance represents a challenge for patient therapeutics. P. aeruginosa is an opportunistic pathogen frequently associated to nosocomial infections, especially in imunocompromised hosts. Objectives: Analyze the phenotypic biofilm production in P. aeruginosa isolates, describe clonal profiles, and analyze quorum sensing (QS genes and the occurrence of mutations in the LasR protein of non-biofilm producing isolates. Methods: Isolates were tested for biofilm production by measuring cells adherence to the microtiter plates. Clonal profile analysis was carried out through ERIC-PCR, QS genes were by specific PCR. Results: The results showed that 77.5% of the isolates were considered biofilm producers. The results of genotyping showed 38 distinct genetic profiles. As for the occurrence of the genes, 100% of the isolates presented the lasR, rhlI and rhlR genes, and 97.5%, presented the lasI gene. In this study nine isolates were not biofilm producers. However, all presented the QS genes. Amplicons related to genes were sequenced in three of the nine non-biofilm-producing isolates (all presenting different genetic similarity profile and aligned to the sequences of those genes in P. aeruginosa strain PAO1 (standard biofilm-producing strain. Alignment analysis showed an insertion of three nucleotides (T, C and G causing the addition of an amino acid valine in the sequence of the LasR protein, in position 53. Conclusion: The modeling of the resulting LasR protein showed a conformational change in its structure, suggesting that this might be the reason why these isolates are unable to produce biofilm. Keywords: Pseudomonas aeruginosa, Biofilm, Multiresistance, Quorum sensing (QS

Assessing the efficacy over time of the addition of industrial by-products to remediate contaminated soils at a pilot-plant scale.

Science.gov (United States)

González-Núñez, Raquel; Rigol, Anna; Vidal, Miquel

2017-04-01

The effect of the addition of industrial by-products (gypsum and calcite) on the leaching of As and metals (Cu, Zn, Ni, Pb and Cd) in a soil contaminated by pyritic minerals was monitored over a period of 6 months at a two-pit pilot plant. The contaminated soil was placed in one pit (non-remediated soil), whereas a mixture of the contaminated soil (80% w/w) with gypsum (10% w/w) and calcite (10% w/w) was placed in the other pit (remediated soil). Soil samples and leachates of the two pits were collected at different times. Moreover, the leaching pattern of major and trace elements in the soil samples was assessed at laboratory level through the application of the pH stat leaching test. Addition of the by-products led to an increase in initial soil pH from around 2.0 to 7.5, and it also provoked that the concentration of trace elements in soil extracts obtained from the pH stat leaching test decreased to values lower than quantification limits of inductively coupled plasma optical emission spectrometry and lower than the hazardous waste threshold for soil management. The trace element concentration in the pilot-plant leachates decreased over time in the non-remediated soil, probably due to the formation of more insoluble secondary minerals containing sulphur, but especially decreased in pit of the remediated soil, in agreement with laboratory data. The pH in the remediated soil remained constant over the 6-month period, and the X-ray diffraction analyses confirmed that the phases did not vary over time, thus indicating the efficacy of the addition of the by-products. This finding suggests that soil remediation may be a feasible option for the re-use of non-hazardous industrial by-products.

The impact of retailers own brand Fair Trade products on developing countries producers

DEFF Research Database (Denmark)

Aguiar, L. K.; Vieira, L. M.; Ferreira, G. C.

Fair Trade certification allows small producers to access international markets and to add value to their products. The Fair-Trade Labelling Organisation certification body (FLOCERT) is responsible for organising and transferring technical information from the consumer market to producers...... in developing countries. Fair trade certification reduces the complexity of transactions and enables producers to adhere to the certification system. FLOCERT exercises governance power in production sites to meet demand by the enforcement of the standards not dissimilar to what happens in global value chains....... Large food retailers have changed practices in the agro-food sector and opened markets to small producers from developing countries. Nevertheless, results reveal that certification imparts in high entry barriers in the form of the need for formal producers' associations, minimum export capacity...

Self-disinfecting Alginate vs Conventional Alginate: Effect on Surface Hardness of Gypsum Cast-An in vitro Study.

Science.gov (United States)

Madhavan, Ranjith; George, Navia; Thummala, Niharika R; Ravi, S V; Nagpal, Ajay

2017-11-01

For the construction of any dental prosthesis, accurate impressions are necessary. Hence, we undertook the present study to evaluate and compare the surface hardness of gypsum casts poured from impressions made using conventional alginate and self-disinfecting alginate. A total of 30 impressions of stainless steel die were made, out of which 15 impressions were made with conventional alginate and 15 were made with self-disinfecting alginate and poured using Type III dental stone. Thirty stone specimens were subjected for hardness testing. Data were analyzed using independent samples t-test to compare the mean surface hardness. Difference in surface hardness was statistically insignificant (p > 0.05). Surface hardness of gypsum casts poured using impressions made from self-disinfecting alginate and conventional alginates were comparable. Self-disinfecting alginates may be employed in clinical practice as safe and effective materials to overcome the infection control issues without compromising on the properties of the material.

Influence of Curing Humidity on the Compressive Strength of Gypsum-Cemented Similar Materials

Directory of Open Access Journals (Sweden)

Weiming Guan

2016-01-01

Full Text Available The analogous simulation experiment is widely used in geotechnical and mining engineering. However, systematic errors derived from unified standard curing procedure have been underestimated to some extent. In this study, 140 gypsum-cemented similar material specimens were chosen to study their curing procedure with different relative humidity, which is 10%–15%, 40%, 60%, and 80%, respectively. SEM microstructures and XRD spectra were adopted to detect the correlation between microstructures and macroscopic mechanical strength during curing. Our results indicated that the needle-like phases of similar materials began to develop in the early stage of the hydration process through intersecting with each other and eventually transformed into mat-like phases. Increase of humidity may inhibit the development of needle-like phases; thus the compressive strength changes more smoothly, and the time required for the material strength to reach the peak value will be prolonged. The peak strength decreases along with the increase of humidity while the humidity is higher than 40%; however, the reverse tendency was observed if the humidity was lower than 40%. Finally, we noticed that the material strength usually reaches the peak value when the water content continuously reduces and tends towards stability. Based on the above observation, a curing method determination model and experimental strength predication method for gypsum-cemented similar materials were proposed.

Organic livestock production: an emerging opportunity with new challenges for producers in tropical countries.

Science.gov (United States)

Chander, M; Subrahmanyeswari, B; Mukherjee, R; Kumar, S

2011-12-01

Agrochemicals, veterinary drugs, antibiotics and improved feeds can increase the food supply while minimising production costs in various livestock production systems around the world. However, these days, quality-conscious consumers are increasingly seeking environmentally safe, chemical-residue-free healthy foods, along with product traceability and a high standard of animal welfare, which organic production methods are said to ensure. Organic production is not only a challenge for producers in developing countries, it offers new export opportunities as well. Organic agriculture is practised by 1.8 million producers in 160 countries, and production of organically grown food continues to increase steadily by 15% per year. Most tropical countries are now exporting organic agricultural products but, apart from organic beef from Brazil and Argentina, organic livestock products are yetto take off. Most trade in organic livestock products is restricted to the European Union and other developed nations. Nevertheless, tropical countries cannot afford to neglect this emerging system of animal production. Organic production is knowledge- and management-intensive. Producers must be well versed in organic production standards, principles and practices, which require a high degree of knowledge and skill. In organic production, it is not simply the final product but the whole production process that must be inspected and approved by the accredited certification bodies. Organic livestock farming is still evolving, and further research is needed to make it sustainable. In this paper, the authors review the prospects of organic animal husbandry and its possible constraints in developing and tropical countries.

Lime and gypsum to improve root depth of orange crop in an Ultisol of the Coastal Tablelands Calcário e gesso no aprofundamento radicular da laranjeira em um Argissolo dos Tabuleiros Costeiros

Directory of Open Access Journals (Sweden)

Lafayette F. Sobral

2009-12-01

Full Text Available Coastal Tableland is a landscape unit in the North East of Brazil in which the main soils are Ultisols. In these soils, a compacted layer denominated "cohesive horizon" occurs and root growth is limited by it. An experiment with five treatments and six replications was set up in order to study how liming and gypsum could improve root depth of orange (Citrus sinensis L. Osbeck crop in an Ultisol in which a compacted layer was found at 0.3 m. Treatments were: A - No liming and no gypsum; B - Liming to achieve 60% base saturation; C - B + 1 t of gypsum ha-1 ; D - B + 2 t of gypsum ha-1 and E - B + 3 t of gypsum ha-1. Gypsum increased calcium and sulfate in the cohesive horizon. Surface application of lime and gypsum did not cause changes in soil density and total porosity in the cohesive horizon. An improvement of root length was observed at the cohesive horizon.Os tabuleiros costeiros são uma unidade de paisagem em que um dos principais solos são os Argissolos, nos quais, uma camada compactada, denominada "horizonte coeso" ocorre e o crescimento radicular é por ela limitado. Um experimento com cinco tratamentos e seis repetições foi implantado para se estudar os efeitos da calagem e do gesso no aprofundamento radicular da laranjeira (Citrus sinensis L. Osbeck em um Argissolo onde o horizonte coeso está a 0,3 m de profundidade. Os tratamentos foram: A - Sem gesso e sem calagem; B - Calagem para atingir 60% de saturação por bases; C - B + 1 t ha-1 de gesso ; D - B + 2 t ha-1 de gesso; e E - B + 3 t ha-1 de gesso. A calagem e o gesso aumentaram significativamente os teores de sulfato e de calcio no solo até a profundidade de 0,40 m. A aplicação a lanço de calcário e gesso não causaram modificações na densidade do solo e na porosidade total da camada compactada "horizonte coeso". Foi observado um aumento do comprimento das raízes da laranjeira na camada compactada.

Application areas of phosphogypsum in production of mineral binders and composites based on them: a review of research results

Directory of Open Access Journals (Sweden)

Dvorkin Leonid

2018-01-01

Full Text Available The increase of the consumption of gypsum products in construction industry with a limited amount of natural gypsum deposits requires alternative sources of gypsum-containing raw materials. In some countries which have fertilizers industry plants, the problem can be solved using industrial wastes, e.g. phosphorgypsum – a byproduct of fertilizers’ production. Kept in dumps over decades, phosphorgypsum is subjected to the chemical changes due to washing out impurities with rain and other natural factors. However, there are observed deviations of harmful impurities in dumped PG depending on its age., Phosphorgypsum of any age requires chemical treatment to neutralize remains of phosphorus and sulfuric acids, fluorine compounds. According to our researches one of the most simple and effective method of neutralization the impurities is using lime-containing admixtures. The paper presents results of laboratory tests of phosphorgypsum as a component of clinker and non-clinker binders. There were investigated the impact of phosphorgypsum as admixture for clinker binders to substitute natural gypsum. Neutralized phosphorgypsum can be applied as mineralizing admixture in calcination of Portland cement clinker. Adding 2 to 2.5% of phosphorgypsum as setting time regulator resulted in a similar physical and mechanical properties compared to mix made with natural gypsum. Another important area of phosphorgypsum application is sulphate activatoion of low-clinker blast-furnace slag cement (clinker content is less than 19%. According to results, the incorporation of phosphorgypsum as sulphate activator in cement has the better effect as natural gypsum. Other development has been carried out to modify the phosphorgypsum binder properties. Complex additive consisted of polycarboxylate-based superplasticizer and slaked lime permitted an increase mechanical properties of hardened phosphorgypsum binder due to significant a reduction of water consumption. Such

Chemical and ecotoxicological evaluation of biochar produced from residues of biogas production.

Science.gov (United States)

Stefaniuk, Magdalena; Oleszczuk, Patryk; Bartmiński, Piotr

2016-11-15

Analyses were carried out for biochars produced at three temperatures of pyrolysis (400, 600 and 800°C) from solid residue from biogas production (RBP). Separated and non-separated RBP from biogas plants employing different biogas production conditions were pyrolyzed. The contents of heavy metals and polycyclic aromatic hydrocarbons (PAHs) (16 PAH US EPA) were analyzed in biochars. The analyses showed that with an increased pyrolysis temperature, there was an increase in the contents of PAHs and of certain heavy metals (Cr, Cu, Cd, Pb and Mn). In the ecotoxicological tests, it was noted that the effect depended on the temperature of pyrolysis and on the feedstock from which the biochar was produced. The least harmful effect on the test organisms was from biochar produced by separated RBP in a biogas plant operating in mesophilic conditions. The most negative effect on the test organisms was characteristic of biochar produced from non-separated mesophilic RBP. This study shows that the main factors determining the level of toxicity of biochars produced from RBP towards various living organisms are both the method of feedstock production and the temperature at which the process of pyrolysis is conducted. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of gypsum ore conversion with aid of gamma-ray transmission and CCRD

International Nuclear Information System (INIS)

Vasconcelos, W.E.; Dantas, C.C.; Lira, C.A.B.O.; Narain, R.; Santos, V.A.

2009-01-01

Nowadays, except for very few kettles imported, the monitoring of the conversion of the produced plaster at the Pole Plaster of Araripe is not done with aid of on-line techniques. It shows a simulation of operational conditions with an online meter of chemically combined water in plaster, by means of Central Composite Rotatable Designs (CCRD) and nuclear technique of gamma-ray transmission. In the family of central composite rotatable designs, the CCRD is more efficient than the others, regarding uniformity of variances of the points at the same distance from the center of the design. It is a simulation of operational conditions with an online meter of chemically combined water in plaster, by means of nuclear technique of gamma radiation transmission. Such determination can be achieved by the effect caused by the variation of the mass attenuation coefficient of the dehydrated partially material. An Americium-241 gamma source (60 keV) was simulated in the implementation of the Beer-Lambert equation. The nuclear data required for simulation were obtained from XMuDat software, available from site of the International Atomic Energy Agency. A program in Matlab programming language has demonstrated the possibility of monitoring at all stages of the dehydration process with measures of the specific mass of the sample having an estimated error of the order of 1%. To verify the operating conditions suitable for the process, experiments were simulated using a CCRD. The independent variables were the thickness sample and chemically combined water in plaster. Optimal conditions of the process were determined (STATISTICA software, Release 7.0), which allowed the derivation of a model represented by response surface of the gypsum conversion. (author)

Further enhanced production of heterologous proteins by double-gene disruption (ΔAosedD ΔAovps10) in a hyper-producing mutant of Aspergillus oryzae.

Science.gov (United States)

Zhu, Lin; Maruyama, Jun-ichi; Kitamoto, Katsuhiko

2013-07-01

The filamentous fungus Aspergillus oryzae is used as one of the most favored hosts for heterologous protein production due to its ability to secrete large amounts of proteins into the culture medium. We previously generated a hyper-producing mutant strain of A. oryzae, AUT1, which produced 3.2- and 2.6-fold higher levels of bovine chymosin (CHY) and human lysozyme (HLY), respectively, compared with the wild-type strain. However, further enhancement of heterologous protein production by multiple gene disruption is difficult because of the low gene-targeting efficiency in strain AUT1. Here, we disrupted the ligD gene, which is involved in nonhomologous recombination, and the pyrG gene to create uridine/uracil auxotrophy in strain AUT1, to generate a hyper-producing mutant applicable to pyrG marker recycling with highly efficient gene targeting. We generated single and double disruptants of the tripeptidyl peptidase gene AosedD and vacuolar sorting receptor gene Aovps10 in the hyper-producing mutant background, and found that all disruptants showed significant increases in heterologous protein production. Particularly, double disruption of the Aovps10 and AosedD genes increased the production levels of CHY and HLY by 1.6- and 2.1-fold, respectively, compared with the parental strain. Thus, we successfully generated a fungal host for further enhancing the heterologous protein production ability by combining mutational and molecular breeding techniques.

Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

KAUST Repository

Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Neal Tai-Shung

2013-01-01

We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI

Fine grinding of brittle minerals and materials by jet mill

Directory of Open Access Journals (Sweden)

Lek Sikong

2008-05-01

Full Text Available Various variables affecting grinding, such as air pressure, minerals or materials hardness, feed size were investigated.The limitations of grinding of gypsum, barite, ilmenite, quartz and ferrosilicon were also elucidated by means of particlefineness size distribution and morphology of ground products. It was found that:1 The density of particles, which are in the grinding zone affects the product fineness, i.e. higher feed rate resultsin a larger product size. The appropriate feed rate is suggested to be 0.2~0.5 g/s. Moreover, the density and hardness ofminerals or materials tend to have an effect on the product fineness. Heavy minerals, such as barite or ilmenite, exhibit afiner product size than lighter minerals, like quartz. However, for quartz, the higher hardness also results in a larger d50.2 Air pressure is the most vital variable which affects the grinding by a jet mill. The d50 seems to relate to theapplied air pressure as a power law equation expressed as following:d50 = aP b ; as P 0The a-value and b-value have been found to correlate to the feed size. The higher the air pressure applied the finerthe product size attained. Moreover, air pressure has a greater effect on hard minerals than on softer ones.3 Feed size seems to have a small effect on ground the product fineness of soft materials, such as gypsum andbarite, but a significant effect on that of hard materials, such as ferrosilicon and quartz, in particularly by milling at low airpressures of 2~3 kg/cm2.4 For the breakage behavior and morphology of ground materials, it was also found that the minerals having cleavages,such as gypsum and barite, tend to be broken along their cleavage planes. Thus, the particle size distribution of theseproducts becomes narrower. While quartz, ilmenite, and ferrosilicon have shattering and chipping breakage mechanisms,grinding results in angular shapes of the ground products and a wider size distribution. Blocks or platelets and

Co-treatment of flotation waste, neutralization sludge, and arsenic-containing gypsum sludge from copper smelting: solidification/stabilization of arsenic and heavy metals with minimal cement clinker.

Science.gov (United States)

Liu, De-Gang; Min, Xiao-Bo; Ke, Yong; Chai, Li-Yuan; Liang, Yan-Jie; Li, Yuan-Cheng; Yao, Li-Wei; Wang, Zhong-Bing

2018-03-01

Flotation waste of copper slag (FWCS), neutralization sludge (NS), and arsenic-containing gypsum sludge (GS), both of which are difficult to dispose of, are major solid wastes produced by the copper smelting. This study focused on the co-treatment of FWCS, NS, and GS for solidification/stabilization of arsenic and heavy metals with minimal cement clinker. Firstly, the preparation parameters of binder composed of FWCS, NS, and cement clinker were optimized to be FWCS dosage of 40%, NS dosage of 10%, cement clinker dosage of 50%, mill time of 1.5 h, and water-to-binder ratio of 0.25. On these conditions, the unconfined compressive strength (UCS) of the binder reached 43.24 MPa after hydration of 28 days. Then, the binder was used to solidify/stabilize the As-containing GS. When the mass ratio of binder-to-GS was 5:5, the UCS of matrix can reach 11.06 MPa after hydration of 28 days, meeting the required UCS level of MU10 brick in China. Moreover, arsenic and other heavy metals in FWCS, NS, and GS were effectively solidified or stabilized. The heavy metal concentrations in leachate were much lower than those in the limits of China standard leaching test (CSLT). Therefore, the matrices were potential to be used as bricks in some constructions. XRD analysis shows that the main hydration products of the matrix were portlandite and calcium silicate hydrate. These hydration products may play a significant role in the stabilization/solidification of arsenic and heavy metals.

Contribution to the study of wastes stabilization by sulfo-aluminate cement

International Nuclear Information System (INIS)

Peysson, S.

2005-02-01

Calcium sulfo-aluminate cement is mainly composed of yeelimite known to be a precursor of ettringite formation. Ettringite is able to incorporate several heavy metals by isomorphous substitutions without altering its crystalline structure. The design of a binder required for immobilizing heavy metals was undertaken. The hydration study of clinker, and cement containing 4 amounts of gypsum has been carried out by means of XRD, DTA and IR spectrometry. It was pointed out that the addition of gypsum enhances hydration. Two binders were selected: 80/20 and 70/30. The immobilisation of 7 pollutants was very successful. Nevertheless, damages appeared with the binder 70/30 containing sodium chromate and dichromate: sodium caused activation of yeelimite reactivity and important dissolution of gypsum leading to important ettringite production. With a great amount of gypsum (30 %), dissolution led to secondary ettringite formation which damaged the hardened paste. Adding polyol enhances the retention of sodium chromate. On the other hand, the immobilisation of two types of weakly radioactive wastes supplied by CEA has been made. Results obtained in terms of setting time, compressive strength and leaching were excellent. (author)

Competitive Dominance by a Bacteriocin-Producing Vibrio harveyi Strain.

Science.gov (United States)

Hoyt, P R; Sizemore, R K

1982-09-01

Vibrio (Beneckea) harveyi, a bioluminescent marine bacterium, has been shown to produce a bacteriocin-like substance the production of which is mediated by a plasmid. This substance is assumed to be proteinaceous because of its sensitivity to certain proteolytic enzymes. It is stable at low temperatures and can be concentrated by ammonium sulfate precipitation or negative-pressure dialysis. The molecular weight of the bacteriocin was determined to be 2.4 x 10 by molecular exclusion chromatography. Competition experiments indicated that bacteriocin-producing strains predominated over cured variants of the same strain in broth culture experiments. We studied several environmental parameters (pH, salinity, temperature, nutrient concentration) to determine their effects on the competitive advantage bestowed on a bacteriocin-producing strain. Under simulated free-living conditions, no competitive advantage attributable to bacteriocin production was observed. In a simulated enteric habitat, a bacteriocin-producing strain showed dramatic (>90%) inhibition of the sensitive strain within 24 h.

Emulsifying behavior of an exopolysaccharide produced by ...

African Journals Online (AJOL)

STORAGESEVER

2008-05-16

May 16, 2008 ... Iyer A, Mody K, Jha B (2005). Characterization of an exopolysaccharide produced by a marine Entrobacter cloaceae. Ind. J. Exp. Biol., 43: 467–471. Matsuda M, Worawattanamateekul W, Okutani K (1992). Simultaneous production of muco- and sulfated polysaccharides by marine. Pseudomonas. Nippon.

Isolation of biosurfactant producers, optimization and properties of biosurfactant produced by Acinetobacter sp. from petroleum-contaminated soil.

Science.gov (United States)

Chen, J; Huang, P T; Zhang, K Y; Ding, F R

2012-04-01

To screen and identify biosurfactant producers from petroleum-contaminated soil; to use response surface methodology (RSM) for medium optimization to enhance biosurfactant production; and to study the properties of the newly obtained biosurfactant towards pH, temperature and salinity. We successfully isolated three biosurfactant producers from petroleum-contaminated soil and identified them through 16S rRNA sequence analysis, which exhibit the highest similarities to Acinetobacter beijerinckii (100%), Kocuria marina (99%) and Kineococcus marinus (99%), respectively. A quadratic response model was constructed through RSM designs, leading to a 57·5% increase of the growth-associated biosurfactant production by Acinetobacter sp. YC-X 2 with an optimized medium: beef extract 3·12 g l(-1) ; peptone 20·87 g l(-1) ; NaCl 1·04 g l(-1); and n-hexadecane 1·86 g l(-1). Biosurfactant produced by Acinetobacter sp. YC-X 2 retained its properties during exposure to a wide range of pH values (5-11), high temperatures (up to 121°C) and high salinities [up to 18% (w/v) Na(+) and Ca(2+) ], which was more sensitive to Ca(2+) than Na(+). Two novel biosurfactant producers were isolated from petroleum-contaminated soil. Biosurfactant from Acinetobacter sp. YC-X 2 has good properties to a wide range of pH, high temperature and high salinity, and its production was optimized successfully through RSM. The fact, an increasing demand of high-quality surfactants and the lack of cost-competitive bioprocesses of biosurfactants for commercial utilization, motivates researchers to develop cost-effective strategies for biosurfactant production through isolating new biosurfactant producers with special surface-active properties and optimizing their cultural conditions. Two novel biosurfactant producers in this study will widen our knowledge about this kind of micro-organism. This work is the first application of RSM designs for cultural optimization of biosurfactant produced by Acinetobacter

Antimicrobial substances produced by bacteria isolated from ...

African Journals Online (AJOL)

SERVER

2007-08-06

Aug 6, 2007 ... We report here the preliminary antimicrobial activity of substances produced by Bacillus subtilis NB-6. (air flora isolate) ... Key words: Antimicrobial activity, Bacillus, Burkholderia, Corynebacterium, methicillin-resistant Staphylococcus aureus. .... products contaminated with animal MRSA is very plausible ...

Gypsum dissolution risk analysis in the Prealpine part of the Vaud County (Western Switzerland)

Science.gov (United States)

Nicolet, Pierrick; Choffet, Marc; Bohren, Delphine; Derron, Marc-Henri; Jaboyedoff, Michel; Lauraux, Bertrand; Lance, Jean-Marc; Champod, Eric

2013-04-01

Subsidence or collapse due to bedrock dissolution is a relatively common phenomenon in Vaud County (Western Switzerland). Indeed, soluble rocks are present in the Jura and Prealpine parts. Solubility is significantly higher in evaporitic rocks (such as gypsum) than in Limestones, resulting in possibly important dissolution during a building's lifetime. In Limestone, subsidence results mainly from cover collapse over existing voids. This study aims at evaluating the cost of this phenomenon for the building portfolio of the region in which gypsum occurs. Currently, 2.5% of the portfolio value is located over gypsum-bearing formations and is therefore potentially affected. Since this phenomenon is not covered by the public building insurance yet, no centralized event record exists. Therefore, a survey has been conducted with the affected communities to estimate the events frequency and damage severity. Some records from the archives of BERTAND LAURAUX SA have been added and allow to compare reparation costs with insured values. From these cases, a frequency and a buildings vulnerability distribution are established. The vulnerability distribution is considered to represent the reality, whereas the frequency is corrected to take into account the different amount of information gathered in the different municipalities and the incompleteness of the inventory, even in the communities with more information. Assuming that the distribution of collapse events occurs with a constant average frequency and is time-independent, insurance financial years are modeled with a number of cases assigned randomly following a Poisson distribution. A Monte Carlo simulation is performed, where the affected buildings value is chosen among the potentially affected portfolio and its corresponding damage rate is assigned following the distribution previously established. The maximum damage for each building is limited to CHF 1,000,000 (EUR 827,000), to ignore unrealistic values. Thus, a cost

Bio-cellulose Production by Beijerinckia fluminensis WAUPM53 and Gluconacetobacter xylinus 0416 in Sago By-product Medium.

Science.gov (United States)

Voon, W W Y; Muhialdin, B J; Yusof, N L; Rukayadi, Y; Meor Hussin, A S

2018-06-19

Bio-cellulose is the microbial extracellular cellulose that is produced by growing several microorganisms on agriculture by-products, and it is used in several food applications. This study aims to utilize sago by-product, coconut water, and the standard medium Hestrin-Schramm as the carbon sources in the culture medium for bio-cellulose production. The bacteria Beijerinkia fluminensis WAUPM53 and Gluconacetobacter xylinus 0416 were selected based on their bio-cellulose production activity. The structure was determined by Fourier transform infrared spectroscopy and scanning electron microscopy, while the toxicity safety was evaluated by brine shrimp lethality test. The results of Fourier transform infrared spectroscopy showed that the bio-cellulose produced by B. fluminensis cultivated in sago by-products was of high quality. The bio-cellulose production by B. fluminensis in the sago by-product medium was slightly higher than that in the coconut water medium and was comparable with the production in the Hestrin-Schramm medium. Brine shrimp lethality test confirmed that the bio-cellulose produced by B. fluminensis in the sago by-product medium has no toxicity, which is safe for applications in the food industry. This is the first study to determine the high potential of sago by-product to be used as a new carbon source for the bio-cellulose production.

Thermochemical reduction of pelletized gypsum mixed with ...

African Journals Online (AJOL)

2015-04-03

Apr 3, 2015 ... Other saleable products such as sulphur may also be produced ... in the absence of air, as air was observed to impact nega- tively on the conversion of ... able mechanical strength to minimize disintegration during handling ...

Farmers Market Brings Fresh Produce and Products from Local Vendors | Poster

Science.gov (United States)

By Carolynne Keenan, Guest Writer Every summer, you can shop for fresh fruits, veggies, flowers, honey, and plenty of other homemade goodies at the NCI at Frederick Farmers’ Market. Buying at the Farmers’ Market means you’re supporting a local farmer, crafter, or other type of vendor. The products are brought to you, so you don’t have to drive to get freshly picked produce and handmade products.

Comparison of Four Strong Acids on the Precipitation Potential of Gypsum in Brines During Distillation of Pretreated, Augmented Urine

Science.gov (United States)

Muirhead, Dean; Carrier, Christopher

2012-01-01

In this study, three different mineral acids were substituted for sulfuric acid (H2SO4) in the urine stabilizer solution to eliminate the excess of sulfate ions in pretreated urine and assess the impact on maximum water recovery to avoid precipitation of minerals during distillation. The study evaluated replacing 98% sulfuric acid with 85% phosphoric acid (H3PO4), 37% hydrochloric acid (HCl), or 70% nitric acid (HNO3). The effect of lowering the oxidizer concentration in the pretreatment formulation also was studied. This paper summarizes the test results, defines candidate formulations for further study, and specifies the injection masses required to stabilize urine and minimize the risk of mineral precipitation during distillation. In the first test with a brine ersatz acidified with different acids, the solubility of calcium in gypsum saturated solutions was measured. The solubility of gypsum was doubled in the brines acidified with the alternative acids compared to sulfuric acid. In a second series of tests, the alternative acid pretreatment concentrations were effective at preventing precipitation of gypsum and other minerals up to 85% water recovery from 95th-percentile pretreated, augmented urine. Based on test results, phosphoric acid is recommended as the safest alternative to sulfuric acid. It also is recommended that the injected mass concentration of chromium trioxide solution be reduced by 75% to minimize liquid resupply mass by about 50%, reduce toxicity of brines, and reduce the concentration of organic acids in distillate. The new stabilizer solution formulations and required doses to stabilize urine and prevent precipitation of minerals up to 85% water recovery are given. The formulations in this study were tested on a limited number of artificially augmented urine batches collected from employees at the Johnson Space Center (JSC). This study successfully demonstrated that the desired physical and chemical stability of pretreated urine and brines

Some parameters of uranium hexafluoride plasma produced by products of nuclear reaction

International Nuclear Information System (INIS)

Batyrbekov, G.A.; Belyakova, Eh.A.

1996-01-01

The probe experimental results of investigation of uranium hexafluoride plasma produced in the centre of nuclear reactor core were demonstrated. Study of uranium hexafluoride plasma is continued by the following reasons: a possibility of U F 6 utilization as nuclear fuel, the utilization of U F 6 as volume source o ionization, search of active laser media compatible with U F 6 that is complicated by lack of constant rates data for most of plasma-chemical reactions with U F 6 and his dissociation products. Cylindrical probe volt-ampere characteristics (VAC) measured in U F 6 plasma at pressure 20 Torr and different thermal neutron fluxes and have following features: -firstly, it is possible to choose a linear part in the field of small positive potentials of probe (0-1) V; - secondary, ion branches of VAC have typical break which current of satiation corresponds to; -thirdly, probe VAC measured at small values of thermal neutron flux density are symmetrical. Diagnostics approaches were used for interpretation VAC of probe. The values of satiation current and linear part of electron branch were calculated, and such plasma parameters as conductivity, diffusion coefficient values of positive and negative ions were determined. The resonance recharge cross section was estimated on diffusion coefficient value

Gypsum-induced decay in granite monuments in Northwestern Spain

Directory of Open Access Journals (Sweden)

Silva Hermo, B.

2010-03-01

Full Text Available One of the most common forms of decay in granite monuments is the detachment of the superficial layer of the stone (plaques, plaquettes and scales. Previous studies of granite monuments in the northwest Iberian Peninsula revealed a direct relation between this type of weathering and the presence of calcium sulphate, and a mechanism whereby the salt causes this type of decay was suggested. In the present study, various hypotheses as regards the origin of the gypsum found in granite monuments are proposed. The study involved analysis of the contents of ions soluble in water, the results of X-ray diffraction analyses and the ratios of CaO/SO₃ in samples of stone, mortar and deposits collected from different monuments. It was concluded that in most cases the gypsum originated from old paintworks or/and from the joint mortars, although inputs from other sources cannot be discounted, as discussed

Una de las formas de deterioro más frecuente en los monumentos graníticos es la separación de la capa superficial de la piedra (placas, plaquetas y escamas. En trabajos anteriores centrados en monumentos del noroeste de la Península Ibérica, se constató la relación directa entre esta forma de alteración y la presencia de sulfato de calcio y se propuso el mecanismo a través del cual esta sal provoca este tipo de deterioro. En este trabajo se plantean varias hipótesis acerca del origen del yeso encontrado en monumentos graníticos. Para ello se comparan los contenidos de iones solubilizados en agua, los resultados de difracción de rayos X y las relaciones OCa/SO₃ de muestras de piedra, morteros y depósitos recogidas en diferentes monumentos. Se llega a la conclusión de que en la mayor parte de los casos el yeso procede de antiguas pinturas o de revestimientos superficiales y de los morteros de juntas entre sillares, pero no se puede descartar la contribución de otros aportes, los cuales se discuten también en este artículo.

Clear Liquor Scrubbing with Anhydrite Production

International Nuclear Information System (INIS)

Hargrove, O. W.; Carey, T. R.; Lowell, P. S.; Meserole, F. B.; Rhudy, R. G.; Feeley, Thomas J.

1997-01-01

The objective of this project to develop an advanced flue gas desulfurization (FGD) process that has decreased capital and operating costs, higher SO 2 removal efficiency, and better by-product solids quality than existing, commercially available technology. A clear liquor process (which uses a scrubbing liquid with no solids) will be used to accomplish this objective rather than a slurry liquor process (which contains solids). This clear liquor scrubbing (CLS) project is focused on three research areas: (1) Development of a clear liquor scrubbing process that uses a clear solution to remove SO 2 from flue gas and can be operated under inhibited-oxidation conditions; (2) Development of an anhydrite process that converts precipitated calcium sulfite to anhydrous calcium sulfate (anhydrite); and (3) Development of an alkali/humidification process to remove HCl from flue gas upstream of the FGD system. The anhydrite process also can be retrofit into existing FGD systems to produce a valuable by-product as an alternative to gypsum. This fits well into another of FETC's PRDA objectives of developing an advanced byproduct recovery subsystem capable of transforming SO 2 into a useable byproduct or high-volume valuable commodities of interest. This paper describes the proposed processes, outlines the test approach, and preliminary Phase I test results

Successful lichen translocation on disturbed gypsum areas: A test with adhesives to promote the recovery of biological soil crusts

Science.gov (United States)

Ballesteros, M.; Ayerbe, J.; Casares, M.; Cañadas, E. M.; Lorite, J.

2017-04-01

The loss of biological soil crusts represents a challenge for the restoration of disturbed environments, specifically in particular substrates hosting unique lichen communities. However, the recovery of lichen species affected by mining is rarely addressed in restoration projects. Here, we evaluate the translocation of Diploschistes diacapsis, a representative species of gypsum lichen communities affected by quarrying. We tested how a selection of adhesives could improve thallus attachment to the substrate and affect lichen vitality (as CO2 exchange and fluorescence) in rainfall-simulation and field experiments. Treatments included: white glue, water, hydroseeding stabiliser, gum arabic, synthetic resin, and a control with no adhesive. Attachment differed only in the field, where white glue and water performed best. Adhesives altered CO2 exchange and fluorescence yield. Notably, wet spoils allowed thalli to bind to the substrate after drying, revealing as the most suitable option for translocation. The satisfactory results applying water on gypsum spoils are encouraging to test this methodology with other lichen species. Implementing these measures in restoration projects would be relatively easy and cost-effective. It would help not only to recover lichen species in the disturbed areas but also to take advantage of an extremely valuable biological material that otherwise would be lost.

Production of sensory compounds by means of the yeast Dekkera bruxellensis in different nitrogen sources with the prospect of producing cachaça.

Science.gov (United States)

Castro Parente, Denise; Vidal, Esteban Espinosa; Leite, Fernanda Cristina Bezerra; de Barros Pita, Will; de Morais, Marcos Antonio

2015-01-01

The distilled spirit made from sugar cane juice, also known as cachaça, is a traditional Brazilian beverage that in recent years has increased its market share among international distilled beverages. Several volatile compounds produced by yeast cells during the fermentation process are responsible for the unique taste and aroma of this drink. The yeast Dekkera bruxellensis has acquired increasing importance in the fermented beverage production, as the different metabolites produced by this yeast may be either beneficial or harmful to the end-product. Since D. bruxellensis is often found in the fermentation processes carried out in ethanol fuel distillation in Brazil, we employed this yeast to analyse the physiological profile and production of aromatic compounds and to examine whether it is feasible to regard it as a cachaça-producing microorganism. The assays were performed on a small scale and simulated the conditions for the production of handmade cachaça. The results showed that the presence of aromatic and branched-chain amino acids in the medium has a strong influence on the metabolism and production of flavours by D. bruxellensis. The assimilation of these alternative nitrogen sources led to different fermentation yields and the production of flavouring compounds. The influence of the nitrogen source on the metabolism of fusel alcohols and esters in D. bruxellensis highlights the need for further studies of the nitrogen requirements to obtain the desired level of sensory compounds in the fermentation. Our results suggest that D. bruxellensis has the potential to play a role in the production of cachaça. Copyright © 2014 John Wiley & Sons, Ltd.

Cost estimation of hydrogen and DME produced by nuclear heat utilization system II

International Nuclear Information System (INIS)

Shiina, Yasuaki; Nishihara, Tetsuo

2004-09-01

Utilization and production of hydrogen has been studied in order to spread utilization of the hydrogen energy in 2020 or 2030. It will take, however, many years for the hydrogen energy to be used very easily like gasoline, diesel oil and city gas in the world. During the periods, low CO 2 release liquid fuels would be used together with hydrogen. Recently, di-methyl-ether (DME). has been noticed as one of the substitute liquid fuels of petroleum. Such liquid fuels can be produced from the mixed gas such as hydrogen and carbon oxide which are produced from natural gas by steam reforming. Therefore, the system would become one of the candidates of future system of nuclear heat utilization. Following the study in 2002, we performed economic evaluation of the hydrogen and DME production by nuclear heat utilization plant where heat generated by HTGR is completely consumed for the production. The results show that hydrogen price produced by nuclear was about 17% cheaper than the commercial price by increase in recovery rate of high purity hydrogen with increased in PSA process. Price of DME in indirect method produced by nuclear heat was also about 17% cheaper than the commercial price by producing high purity hydrogen in the DME producing process. As for the DME, since price of DME produced near oil land in petroleum exporting countries is cheaper than production in Japan, production of DME by nuclear heat in Japan has disadvantage economically in this time. Trial study to estimate DME price produced by direct method was performed. From the present estimation, utilization of nuclear heat for the production of hydrogen would be more effective with coupled consideration of reduction effect of CO 2 release. (author)

Experienced materials in wet limestone-gypsum FGD system

Energy Technology Data Exchange (ETDEWEB)

Hasegawa, S. [Mitsubishi Heavy Industry, Hiroshima (Japan). Hiroshima Research and Development Center; Iwashita, K.; Ochi, E.; Higuchi, T. [Mitsubishi heavy Industry, Yokohama (Japan)

1998-12-31

This study was made on the corrosion resistivity evaluation method used for material selection in the Wet Limestone-Gypsum FGD system with examples of various process configuration, their corrosion environment, and the materials used in them. The wet limestone-gypsum process FGD plant is broadly divided into two types-ash-separated (dual-loop) process, and ash-mixed (single-loop) process-depending on whether the flue gas is separated from ash before being led into the absorber or led as it is into the absorber mixed with ash. Presently, the single-loop process has become the mainstream process however. The dual -loop process comprises a dedusting tower (quencher) and an absorption tower (absorber). In the quencher ash is removed with sprayed water where most of the HCl, HF etc., and a part of SO{sub x} and NO{sub x} contained in the flue gas are also removed with absorption. On the contrary, in the single-loop process which is configured of only the absorber, the flue gas is introduced into it as it is contained with ash, SO{sub x}, NO{sub x}, HCl, HF etc. The corrosion environment in these plants largely differs depending on the process type and condition. The absorber recirculated liquid has various ion inclusions among which Cl{sup {minus}} promotes pitting corrosion and crevice corrosion while SO{sub 4}{sup 2{minus}} inhibits these corrosions. Both Cl{sup {minus}} and SO{sub 4}{sup 2{minus}} cover an extremely large range between 25 to 100,000 ppm and 564 to 73,600 ppm respectively, and their influence on the corrosion is related to their activity which is decided by Ca{sup 2+}, Mg{sup 2+}, Na{sup +}, NH{sub 4}{sup +}, H{sup +} and liquid temperature. The balance of these ions is decided by the gas composition, limestone composition, make-up water and wastewater mass balance etc., of individual plants. Accordingly, materials of FGD plant are selected on the basis of evaluated results of corrosion resistivity test made under such simulated process conditions of

Thermostable crude endoglucanase produced by Aspergillus ...

African Journals Online (AJOL)

Cellulases are used in many industries worldwide and there is an ever increasing need to isolate, produce or develop thermostable cellulases. Manipulation of fermentation techniques in order to obtain desirable product(s) can be one line of action. In this study Aspergillus fumigatus was grown on chopped wheat straw in a ...

Shallow groundwater and soil chemistry response to 3 years of subsurface drip irrigation using coalbed-methane-produced water

Energy Technology Data Exchange (ETDEWEB)

Bern, C. R.; Boehlke, A. R.; Engle, M. A.; Geboy, N. J.; Schroeder, K. T.; Zupancic, J. W.

2013-10-04

Disposal of produced waters, pumped to the surface as part of coalbed methane (CBM) development, is a significant environmental issue in the Wyoming portion of the Powder River Basin, USA. High sodium adsorption ratios (SAR) of the waters could degrade agricultural land, especially if directly applied to the soil surface. One method of disposing of CBM water, while deriving beneficial use, is subsurface drip irrigation (SDI), where acidified CBM waters are applied to alfalfa fields year-round via tubing buried 0.92 m deep. Effects of the method were studied on an alluvial terrace with a relatively shallow depth to water table (~3 m). Excess irrigation water caused the water table to rise, even temporarily reaching the depth of drip tubing. The rise corresponded to increased salinity in some monitoring wells. Three factors appeared to drive increased groundwater salinity: (1) CBM solutes, concentrated by evapotranspiration; (2) gypsum dissolution, apparently enhanced by cation exchange; and (3) dissolution of native Na–Mg–SO{sub 4} salts more soluble than gypsum. Irrigation with high SAR (24) water has increased soil saturated paste SAR up to 15 near the drip tubing. Importantly though, little change in SAR has occurred at the surface.

Shallow groundwater and soil chemistry response to 3 years of subsurface drip irrigation using coalbed-methane-produced water

Science.gov (United States)

Bern, Carleton R.; Boehlke, Adam R.; Engle, Mark A.; Geboy, Nicholas J.; Schroeder, K.T.; Zupancic, J.W.

2013-01-01

Disposal of produced waters, pumped to the surface as part of coalbed methane (CBM) development, is a significant environmental issue in the Wyoming portion of the Powder River Basin, USA. High sodium adsorption ratios (SAR) of the waters could degrade agricultural land, especially if directly applied to the soil surface. One method of disposing of CBM water, while deriving beneficial use, is subsurface drip irrigation (SDI), where acidified CBM waters are applied to alfalfa fields year-round via tubing buried 0.92 m deep. Effects of the method were studied on an alluvial terrace with a relatively shallow depth to water table (∼3 m). Excess irrigation water caused the water table to rise, even temporarily reaching the depth of drip tubing. The rise corresponded to increased salinity in some monitoring wells. Three factors appeared to drive increased groundwater salinity: (1) CBM solutes, concentrated by evapotranspiration; (2) gypsum dissolution, apparently enhanced by cation exchange; and (3) dissolution of native Na–Mg–SO4 salts more soluble than gypsum. Irrigation with high SAR (∼24) water has increased soil saturated paste SAR up to 15 near the drip tubing. Importantly though, little change in SAR has occurred at the surface.

Metals in soil and runoff from a piedmont hayfield amended with broiler litter and flue gas desulfurization gypsum

Science.gov (United States)

Flue gas desulfurization gypsum (FGDG) from coal-fired power plants is available for agricultural use in many US regions. Broiler litter (BL) provides plant available N, P, and K but may be a source of unwanted arsenic (As), copper (Cu), and zinc (Zn). FGDG provides Ca and S and can reduce runoff lo...

Investigation of the potential influence of production treatment chemicals on produced water toxicity

International Nuclear Information System (INIS)

Stine, E.R.; Gala, W.R.; Henry, L.R.

1993-01-01

Production treatment chemicals represent a diverse collection of chemical classes, added at various points from the wellhead to the final flotation cell, to prevent operational upsets and enhance the separation of oil from water. Information in the literature indicates that while many treatment chemicals are thought to partition into oil and not into the produced water, there are cases where a sufficiently water soluble treatment chemical is added at high enough concentrations to suggest that the treatment chemical may add to the aquatic toxicity of the produced water. A study was conducted to evaluate the potential effect of production treatment chemicals on the toxicity of produced waters using the US EPA Seven-day Mysidopsis bahia Survival, Growth and Fecundity Test. Samples of produced water were collected and tested for toxicity from three platforms under normal operating conditions, followed by repeated sampling and testing after a 72-hour period in which treatment chemical usage was discontinued, to the degree possible. Significant reductions in produced water toxicity were observed for two of the three platforms tested following either cessation of treatment chemical usage, or by comparing the toxicity of samples collected upstream and downstream of the point of treatment chemical addition

Emissions reduction in the UK: accommodating waste production from sulphur abatement systems

Energy Technology Data Exchange (ETDEWEB)

Crofts, C. (British Coal, London (UK). Operational Research Executive)

1990-01-01

Concern for the atmosphere environment has resulted in EC legislation limiting sulphur dioxide emissions. The emission limits are being met by the installation of flue gas desulphurisation and advanced coal combustion systems, which produce large quantities of waste for utilisation or disposal. There are now environmental, economic and regulatory reasons for industry to provide comprehensive assessment of waste disposal/utilisation issues during the design stage of a project. This paper considers the management of waste produced from the limestone/gypsum and spray dry FGD processes, and from advanced coal combustion equipment. The assessment shows that environmentally acceptable methods of disposal and utilisation can be identified for these wastes. It is expected that a substantial proportion of FGD gypsum will be utilized in the manufacture of plasterboard, bag plaster and cement. There may also be opportunities for utilisation of spray dry waste and waste from advanced coal combustion systems in structural and agricultural applications. Landfill would be an appropriate form of disposal for the wastes considered in this paper, but utilisation options offer environmentally superior alternatives to disposal justifying further research. 19 refs., 3 figs.

Producing energy while sequestering carbon? The relationship between biochar and agricultural productivity

International Nuclear Information System (INIS)

Kauffman, Nathan; Dumortier, Jerome; Hayes, Dermot J.; Brown, Robert C.; Laird, David A.

2014-01-01

A partial solution to problems associated with anthropogenic greenhouse gas (GHG) emissions could be the development and deployment of carbon-negative technologies, i.e., producing energy while reducing atmospheric carbon dioxide levels. Biofuels have been considered a possibility but have faced limitations due to competition with food production and GHG emissions through indirect land-use change (ILUC). In this article, we show how emissions from ILUC can potentially be reduced by producing food and bioenergy from biochar amended soils. The possibility of yield improvements from biochar would reduce the land requirement for crop production and thus, lead to a reduction in emissions from ILUC. In our application, biochar and bio-oil are produced via fast pyrolysis of corn stover. Bio-oil is subsequently upgraded into a fuel suitable for use in internal combustion engines. Applying the U.S. regulatory method used to determine biofuel life cycle emissions, our results show that a biochar-induced yield improvement in the U.S. Midwest ranging from 1% to 8% above trend can lead to an ILUC credit between 1.65 and 14.79 t CO 2 -equivalent ha −1  year −1 when future emissions are assessed over the next 30 years. The model is generalizable to other feedstocks and locations and illustrates the relationship between biochar and crop production. - Highlights: • If biochar leads to higher crop yields, a land-use change (LUC) credit applies. • Indirect LUC credit is applied to biofuel if biochar is produced as a by-product. • 1.65 to 14.79 t CO 2 -e ha −1  year −1 credit for 1%–8% yield increase in U.S. Midwest. • Life cycle analysis generalizable to other locations and feedstock

Examination of the jarosite-alunite precipitate addition in the raw meal for the production of sulfoaluminate cement clinker.

Science.gov (United States)

Katsioti, M; Tsakiridis, P E; Leonardou-Agatzini, S; Oustadakis, P

2006-04-17

The aim of the present research work was to investigate the possibility of adding a jarosite-alunite chemical precipitate, a waste product of a new hydrometallurgical process developed to treat economically low-grade nickel oxides ores, in the raw meal for the production of sulfoaluminate cement clinker. For that reason, two samples of raw meals were prepared, one contained 20% gypsum, as a reference sample ((SAC)Ref) and another with 11.31% jarosite-alunite precipitate ((SAC)J/A). Both raw meals were sintered at 1300 degrees C. The results of chemical and mineralogical analyses as well as the microscopic examination showed that the use of the jarosite-alunite precipitate did not affect the mineralogical characteristics of the so produced sulfoaluminate cement clinker and there was confirmed the formation of the sulfoaluminate phase (C4A3S), the most typical phase of this cement type. Furthermore, both clinkers were tested by determining the grindability, setting time, compressive strength and expansibility. The hydration products were examined by XRD analysis at 2, 7, 28 and 90 days. The results of the physico-mechanical tests showed that the addition of jarosite-alunite precipitate did not negatively affect the quality of the produced cement.

Ethanol Production from Enzymatically Treated Dried Food Waste Using Enzymes Produced On-Site

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Leonidas Matsakas

2015-01-01

Full Text Available The environmental crisis and the need to find renewable fuel alternatives have made production of biofuels an important priority. At the same time, the increasing production of food waste is an important environmental issue. For this reason, production of ethanol from food waste is an interesting approach. Volumes of food waste are reduced and ethanol production does not compete with food production. In this work, we evaluated the possibility of using source-separated household food waste for the production of ethanol. To minimize the cost of ethanol production, the hydrolytic enzymes that are necessary for cellulose hydrolysis were produced in-house using the thermophillic fungus Myceliophthora thermophila. At the initial stage of the study, production of these thermophilic enzymes was studied and optimized, resulting in an activity of 0.28 FPU/mL in the extracellular broth. These enzymes were used to saccharify household food waste at a high dry material consistency of 30% w/w, followed by fermentation. Ethanol production reached 19.27 g/L with a volumetric productivity of 0.92 g/L·h, whereas only 5.98 g/L of ethanol was produced with a volumetric productivity of 0.28 g/L·h when no enzymatic saccharification was used.

Recuperação de solos afetados por sais pela aplicação de gesso de jazida e calcário no Nordeste do Brasil Reclamation of salt-affected soils in Northeast Brazil with application of mined gypsum and limestone

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Maria de F. C. Barros

2004-04-01

was indicated by a positive effect on the physical and chemical characteristics of the soils, therefore these may be recommended as calcium source for the reclamation of the saline-sodic soils. Among the gypsum granulometry, the fine fractions (0.5 - 0.3 and < 0.3 mm, presented better performance in leaching salt and in the reduction of sodium adsorption ratio (SAR in saturation extract.

Prostaglandin E2 produced by Entamoeba histolytica binds to EP4 receptors and stimulates interleukin-8 production in human colonic cells.

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Dey, Indranil; Chadee, Kris

2008-11-01

Entamoeba histolytica pathogenesis in the colon occurs in a stepwise fashion. It begins with colonization of the mucin layer, which is followed by stimulation of a proinflammatory response that causes nonspecific tissue damage that may facilitate parasite invasion of the underlying colonic mucosa. Unfortunately, the parasite and/or host factors that stimulate a proinflammatory response in the gut are poorly understood. In this study, we found that live E. histolytica or secretory or proteins (SP) and soluble ameba components (SAP) can markedly increase interleukin-8 (IL-8) mRNA expression and protein production in colonic epithelial cells. The IL-8-stimulating molecule produced by live amebae was identified as prostaglandin E(2) (PGE(2)) as trophozoites treated with cyclooxygenase inhibitors inhibited the biosynthesis of PGE(2) and eliminated IL-8 production induced by live parasites or ameba components. Moreover, using specific prostaglandin EP2 and EP4 receptor agonists and antagonists, we found that PGE(2) binds exclusively through EP4 receptors in colonic epithelial cells to stimulate IL-8 production. Silencing of EP4 receptors with EP4 small interfering RNA completely eliminated SP- and SAP-induced IL-8 production. These studies identified bioactive PGE(2) as a one of the major virulence factors produced by E. histolytica that can stimulate the potent neutrophil chemokine and activator IL-8, which can trigger an acute host inflammatory response. Thus, the induction of IL-8 production in response to E. histolytica-derived PGE(2) may be a mechanism that explains the initiation and amplification of acute inflammation associated with intestinal amebiasis.

Model of gypsum, calcite and silica solubilities for application to geothermal waters over a wide range of temperature, P/sub CO/sub 2// and ionic strength. Final technical report, October 1, 1983-September 30, 1984

Energy Technology Data Exchange (ETDEWEB)

1984-01-01

This report describes the construction of a high temperature (25 to 250/sup 0/C), variable P/sub CO/sub 2// (1 to 40 atm), chemical model of mineral (including gypsum, calcite and amorphous silica) solubilities in the system: Na-K-Ca-H-Cl-SO/sub 4/-HCO/sub 3/-CO/sub 3/-CO/sub 2/-SiO/sub 2/-H/sub 2/O. This model was designed to support geothermal energy production needs.

Assessing the potential of fatty acids produced by filamentous fungi as feedstock for biodiesel production.

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Rivaldi, Juan Daniel; Carvalho, Ana Karine F; da Conceição, Leyvison Rafael V; de Castro, Heizir F

2017-11-26

Increased costs and limited availability of traditional lipid sources for biodiesel production encourage researchers to find more sustainable feedstock at low prices. Microbial lipid stands out as feedstock replacement for vegetable oil to convert fatty acid esters. In this study, the potential of three isolates of filamentous fungi (Mucor circinelloides URM 4140, M. hiemalis URM 4144, and Penicillium citrinum URM 4126) has been assessed as single-cell oil (SCO) producers. M. circinelloides 4140 had the highest biomass concentration with lipid accumulation of up to 28 wt% at 120 hr of cultivation. The profile of fatty acids revealed a high content of saturated (SFA) and monounsaturated fatty acids (MUFA), including palmitic (C16:0, 33.2-44.1 wt%) and oleic (C18:1, 20.7-31.2 wt%) acids, with the absence of polyunsaturated fatty acids (PUFA) having more than four double bonds. Furthermore, the predicted properties of biodiesel generated from synthesized SCOs have been estimated by using empirical models which were in accordance with the limits imposed by the USA (ASTM D6715), European Union (EN 14214), and Brazilian (ANP 45/2014) standards. These results suggest that the assessed filamentous fungus strains can be considered as alternative feedstock sources for high-quality biofuel production.

Acetaldehyde production by major oral microbes.

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Moritani, K; Takeshita, T; Shibata, Y; Ninomiya, T; Kiyohara, Y; Yamashita, Y

2015-09-01

To assess acetaldehyde (ACH) production by bacteria constituting the oral microbiota and the inhibitory effects of sugar alcohols on ACH production. The predominant bacterial components of the salivary microbiota of 166 orally healthy subjects were determined by barcoded pyrosequencing analysis of the 16S rRNA gene. Bacterial ACH production from ethanol or glucose was measured using gas chromatography. In addition, inhibition by four sugars and five sugar alcohols of ACH production was assayed. Forty-one species from 16 genera were selected as predominant and prevalent bacteria based on the following criteria: identification in ≥95% of the subjects, ≥1% of mean relative abundance or ≥5% of maximum relative abundance. All Neisseria species tested produced conspicuous amounts of ACH from ethanol, as did Rothia mucilaginosa, Streptococcus mitis and Prevotella histicola exhibited the ability to produce ACH. In addition, xylitol and sorbitol inhibited ACH production by Neisseria mucosa by more than 90%. The oral microbiota of orally healthy subjects comprises considerable amounts of bacteria possessing the ability to produce ACH, an oral carcinogen. Consumption of sugar alcohols may regulate ACH production by oral microbes. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

CRESCIMENTO RADICULAR E NUTRIÇÃO DA CEVADA EM FUNÇÃO DA CALAGEM E APLICAÇÃO DE GESSO BARLEY NUTRITION AND ROOT GROWTH AS AFFECTED BY LIME AND GYPSUM APPLICATIONS

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EDUARDO FÁVERO CAIRES

2001-01-01

.Root growth can be affected by chemical modifications in the soil profile due to lime and gypsum applications. A field trial was carried out on a dystrophic Clay Rhodic Hapludox at Ponta Grossa, State of Paraná, Brazil, aiming at evaluating lime and gypsum effects on root growth and plant chemical traits of barley, cv. BR 2 (Al susceptible. A randomized complete block design was used, with three replications, in a split-plot layout. The main plots received dolomitic limestone treatments (no lime and 4.5 t.ha-1 of lime-on the surface or incorporated into the soil and the subplots, the rates of gypsum (0, 3, 6 and 9 t.ha-1, applied in the installation of a no-tillage system, in 1998. Barley was grown during the 1999 winter season, after the soybean crop. Liming (whether surface applied or incorporated into the soil, and gypsum rates did not significantly affected barley root growth, although gypsum provided better root relative distribution in the soil profile, mainly when associated to liming. Under severe water stress conditions there was no limitation to barley root growth in depth (for 6 mmol c.dm-3 exchangeable Ca and 35% Al saturation. Lime incorporation improved the plant nutrition as to N and K, but liming treatments did not affect grain yields-these were limited by the prolonged water deficit during flowering stage. However, gypsum increased N, P, K, Ca and S plant levels, even under water stress conditions, with significant effects on grain yields, due to increases in the exchangeable Ca, Ca/Mg relationships and S-SO4(2- levels available in the soil.

Selection of antifungal protein-producing molds from dry-cured meat products.