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PubMed2006

Co-composting of acid waste bentonites and their effects on soil properties and crop biomass.

Acid waste bentonite is a byproduct from vegetable oil bleaching that is acidic (pH < 3.0) and hydrophobic. These materials are currently disposed of in landfills and could potentially have a negative impact on the effective function of microbes that are intolerant of acidic conditions. A study was undertaken using three different sources of acid waste bentonites, namely soybean oil bentonite (SB), palm oil bentonite (PB), and rice bran oil bentonite (RB). These materials were co-composted with rice husk, rice husk ash, and chicken litter to eliminate their acid reactivity and hydrophobic nature. The organic carbon (OC) content, pH, exchangeable cations, and cation exchange capacity (CEC) of the acid-activated bentonites increased significantly after the co-composting phase. In addition, the hydrophobic nature of these materials as measured using the water drop penetration time (WDPT) decreased from >10 800 s to 16 to 80 s after composting. Furthermore, these composted materials showed positive impacts on soil physical attributes including specific surface area, bulk density, and available water content for crop growth. Highly significant increases in maize biomass (Zea mays L.) production over two consecutive cropping cycles was observed in treatments receiving co-composted bentonite. The study clearly demonstrates the potential for converting an environmentally hazardous material into a high-quality soil conditioner using readily available agricultural byproducts. It is envisaged that the application of these composted acid waste bentonites to degraded soils will increase productivity and on-farm income, thus contributing toward food security and poverty alleviation.

Bentonite↗
PubMed2004

[Removal of red tide organisms by organo-modified bentonite].

A series of organo-bentonites were synthesized by exchanging cation surfactants such as cyltrimethylammonium bromide and cetyltrimethylammonium to remove red tide organisms Skeletonema costatum. The results showed that the removal rate of Skeletonema costatum by the bentonites was in the order of cyltrimethylammonium surfactant modified iron pillared bentonite > cetyltrimethylammoium surfactant modified iron pillared bentonite > iron pillared bentonite > cyltrimethylammonium surfactant modified sodium bentonite > cetyltrimethylammoium surfactant modified > sodium bentonite. The removal rate of Skeletonema costatum was related to the length of alkyl chains and the amount of cation surfactants exchanged on bentonites.

Animals↗
PubMed2004

Diffusion of Eu(III) in compacted bentonite-effect of pH, solution concentration and humic acid.

The effect of pH, Eu(III) solution concentration and humic acid on the diffusion of Eu(III) in compacted bentonite (rho(b) = 1000 +/- 30 kg/m(3)) was studied with "in-diffusion" method at an ionic strength of 0.1M NaClO(4). The results (K(d) values from the first slice and theoretical calculation, apparent and effective diffusion coefficients) derived from the new capillary method are in good agreement with the literature data under similar conditions, and fit the Fick's second law very well. The results suggest that the diffusion of Eu(III) is dependent on pH values and independent on solution concentration in our experimental conditions. Humic acid forms precipitation/complexation with Eu(III) at the surface of compacted bentonite and thus deduces the diffusion/transport of Eu(III) in compacted bentonite. The K(d) values in compacted bentonite are in most cases lower than those in powdered bentonite obtained from batch experiments. The difference between the K(d) values from powdered and compacted bentonite is a strong function of the bulk density of the bentonite. The results suggest that the content of interlaminary space plays a very important role to the diffusion, sorption and migration of Eu(III) in compacted bentonite.

Journal Article↗
PubMed2000

Adsorption of phenol by bentonite.

The potential of bentonite for phenol adsorption from aqueous solutions was studied. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, initial concentration, pH, presence of solvent, and the desorption characteristics of bentonite. The adsorption of phenol increases with increasing initial phenol concentration and decreases with increasing the solution pH value. The adsorption process was significantly influenced by the solvent type in which phenol was dissolved. The affinity of phenol to bentonite in the presence of cyclohexane was greater than that in water and was lowest in the presence of methanol. Methanol was used to extract phenol from bentonite. The degree of extraction was dependent on the amount of phenol adsorbed by bentonite. X-ray diffraction analysis showed that the crystalline structure of bentonite was destroyed when cyclohexane was used. The ability of bentonite to adsorb phenol from cyclohexane decreased as the water to cyclohexane ratio was increased. Furthermore, hysteresis was observed in phenol desorption from bentonite in aqueous solutions. The equilibrium data in aqueous solutions was well represented by the Langmuir and Freundlich isotherm models. The removal of phenol from aqueous solutions was observed without surface modification.

Journal Article↗
PubMed2005

Adsorption of zinc from aqueous solutions to bentonite.

The adsorptive properties of natural and Na-enriched bentonite in zinc rich aqueous environment have been studied. The results show that adsorption behavior of both bentonites was strongly depending on the pH. At low pH values, the mechanisms that govern the adsorption behavior of bentonites are dissolution of crystal structure and competition of the metal ions with the H+. Between pH 4 and 7, the basic mechanism is an ion exchange process. The alkaline and alkaline earth metals located in the exchangeable sites of bentonites are replaced with Zn2+ cations present in the aqueous solution. At higher pH values (i.e. pH 8), formation of zinc hydroxyl species may result either participation to the adsorption or precipitation onto the bentonites. Therefore, a rapid increase in the equilibrium removal of zinc was obtained above pH 7. Increase in the initial metal ion concentration led to the increase in equilibrium adsorption to a certain degree; then, a plateau was obtained at higher concentrations. The rate of zinc removal depends also on the solid concentration of the suspension. Reducing the slurry concentration allows particles to get in the more dispersed form, resulting higher available sorption sites for zinc. As a result, the adsorption performance of Na-enriched bentonite is better than the natural bentonite in all physical and chemical changes. The data were fitted both Langmuir and Freundlich isotherms.

Adsorption↗
PubMed2005

Mechanisms of advanced oxidation processing on bentonite consumption reduction in foundry.

Prior full-scale foundry data have shown that when an advanced oxidation (AO) process is employed in a green sand system, the foundry needs 20-35% less makeup bentonite clay than when AO is not employed. We herein sought to explore the mechanism of this enhancement and found that AO water displaced the carbon coating of pyrolyzed carbonaceous condensates that otherwise accumulated on the bentonite surface. This was discerned by surface elemental analysis. This AO treatment restored the clay's capacity to adsorb methylene blue (as a measure of its surface charge) and water vapor (as a reflection of its hydrophilic character). In full-scale foundries, these parameters have been tied to improved green compressive strength and mold performance. When baghouse dust from a full-scale foundry received ultrasonic treatment in the lab, 25-30% of the dust classified into the clay-size fraction, whereas only 7% classified this way without ultrasonics. Also, the ultrasonication caused a size reduction of the bentonite due to the delamination of bentonite particles. The average bentonite particle diameter decreased from 4.6 to 3 microm, while the light-scattering surface area increased over 50% after 20 min ultrasonication. This would greatly improve the bonding efficiency of the bentonite according to the classical clay bonding mechanism. As a combined result of these mechanisms, the reduced bentonite consumption in full-scale foundries could be accounted for.

Adsorption↗
PubMed2006

Severe hypokalemia caused by oral and rectal administration of bentonite in a pediatric patient.

BACKGROUND: Bentonite is a clay substance that has been used as a homeopathic cathartic. Oral ingestion of bentonite in large quantities has the potential to cause gastrointestinal obstruction and electrolyte abnormalities. We present a case of severe hypokalemia in a pediatric patient who received both oral and rectal administrations of bentonite. CASE: A 3-year-old girl presented with a chief complaint of vomiting, constipation, lethargy, and weakness over several days. On initial evaluation, the child was mildly dehydrated and had a serum potassium of 0.9 mmol/L. Electrocardiographic findings were also consistent with hypokalemia. Upon further questioning, the parents reported that they had been administering a home remedy, containing colloidal bentonite, both orally and rectally as treatment for persistent constipation. The child received intravenous antibiotics, a normal saline bolus, and multiple boluses of potassium chloride, resulting in eventual normalization of her electrolyte abnormalities. CONCLUSION: Ingestion of large quantities of clay substances, such as bentonite, can result in gastrointestinal binding of essential electrolytes and possible obstruction. Symptoms and laboratory values often resolve with replacement of electrolytes and cessation of bentonite intake. Although cases of oral ingestion of clay-like substances resulting in electrolyte abnormalities have been reported, there are no previously reported human cases of hypokalemia caused specifically by bentonite administration. This may be due to the unique rectal administration seen in this child, which has not previously been described.

Administration, Oral↗
PubMed2006

Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization.

Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder.

Bentonite↗
PubMed1992

Effects of bentonite on wool growth and nitrogen metabolism in fauna-free and faunated sheep.

Two experiments were carried out with sheep that originated from a fauna-free flock and were fed a soybean meal-corn silage diet with or without a bentonite supplement. One-half of the sheep fed each diet in each experiment were faunated with a mixed population of ruminal protozoa, whereas the other half of the sheep remained fauna-free until the end of both experiments. Wool growth and daily gain were measured in Exp. 1. (eight rams per treatment), which lasted 110 d, and the metabolic effects in the rumen and intestinal tract of protozoa and dietary bentonite supplement were tested with cannulated wethers (four wethers per treatment) in Exp. 2. The results of Exp. 1 showed decreased wool growth (P less than .05) due to the presence of protozoa in the rumen. Dietary supplementation with bentonite partly offset the decreased wool growth in sheep with protozoa, but there were no effects of dietary bentonite and no protozoa x bentonite interaction (P greater than .05). Daily gain was decreased by the dietary bentonite (P less than .05) supplement but was not affected (P greater than .05) by the ruminal presence of protozoa. In Exp. 2, protozoa increased (P less than .01) the ruminal concentrations of ammonia and decreased (P less than .05) the acetic:propionic acid molar ratio. Fractionation of N in the duodenal digesta flowing from the stomach to the small intestine showed that protozoa decreased (P less than .05) the flow of nonammonia N and bacterial N, and there was a protozoa x bentonite interaction for these effects (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Effects of bentonite and monensin on selected elements in the stomach and liver of fauna-free and faunated sheep.

Forty-eight rams, originating from a fauna-free flock, were divided into three groups of 16 and fed a corn silage-based diet that was unsupplemented (control) or included bentonite or monensin supplements. Eight rams in each group were inoculated with a mixed population of ruminal protozoa; the other rams remained free of protozoa throughout the 110-d experiment. The rams had free access to drinking water and assigned diet. All rams were killed at the end of the experiment, and ruminal and abomasal contents and livers were removed and sampled. Protozoal numbers in ruminal fluid of faunated rams were lower for groups fed bentonite or monensin supplements than for the control group. Bentonite decreased and monensin increased ruminal pH. The ruminal solubilities of Cu, Zn, and Mg were decreased by the presence of ruminal protozoa, but those of Fe, Mn, and Ca were not affected. Bentonite supplement decreased, and monensin supplement increased, the ruminal solubilities of Cu, Zn, and Mg. Protozoa increased the abomasal solubilities of Fe, but the other elements were not affected. Liver concentrations of Cu were decreased by bentonite and increased by monensin, but protozoa decreased the liver concentrations of both Cu and Mg. Liver concentration of Zn was affected by a monensin x protozoa interaction and that of Mg by a bentonite x protozoa interaction. It was concluded that chronic Cu poisoning could be accelerated by dietary supplements of monensin in sheep without ruminal microfauna, and the dietary Cu bioavailability could be decreased by dietary supplements of bentonite in sheep with a normal population of protozoa in the rumen.

Abomasum↗
PubMed2002

In vitro adsorption of lithium by bentonite.

BACKGROUND: Lithium poisoning is currently managed using a combination of supportive care and urgent haemodialysis in severe cases. Activated charcoal as a gut decontaminant has been found to be ineffective. The use of Sodium Polystyrene Sulphonate (SPS) as an adsorbent has been found to be effective in some studies. However, there have been case reports of gut necrosis and perforation occurring when SPS was used for the treatment of hyperkalaemia in post operative patients or patients with renal failure. Bentonite is a known adsorbent that has been used in the management of paraquat poisonings. The purpose of this study was to determine the ability of bentonite to adsorb lithium. METHOD: 4.5 g of lithium carbonate was dissolved in 1.5 L of deionised water to form the stock solution. 50 mL aliquots of this stock solution were added to 50 mL of either distilled deionised water (pH 7) or simulated gastric fluid (pH 1.2). Bentonite of either 0.75, 1.5 or 4.5 g was then added to simulate 5:1, 10:1 and 30:1 ratio of adsorbent-to-drug. Controls were made with no bentonite added. The resulting mixture was placed on a shaker for five minutes before being filtered. The filtrate was diluted and batch analysed for lithium using atomic absorption spectrophotometry. RESULTS: Bentonite decreased the concentration of lithium recovered from the filtrate by 20.55% in deionised water compared to 48.09% in simulated gastric fluid at a bentonite:lithium ratio of 30:1 (p value 0.005). CONCLUSION: This study shows that bentonite is an effective adsorbent for lithium. The effect is enhanced in simulated gastric fluid. In vivo studies are being planned for clinical correlation.

Adsorption↗
PubMed2005

Acid-base properties of bentonite rocks with different origins.

Five bentonite samples (35-47% montmorillonite) from a Sarmatian sediment series with bentonite sites around Sajóbábony (Hungary) is studied. Some of these samples were tuffogenic bentonite (sedimentary), the others were bentonitized tuff with volcano sedimentary origin. The acid-base properties of the edge sites were studied by potentiometric titrations and surface complexation modeling. It was found that the number and the ratio of silanol and aluminol sites as well as the intrinsic stability constants are different for the sedimentary bentonite and bentonitized tuff. The characteristic properties of the edges sites depend on the origins. The acid-base properties are compared to other commercial and standard bentonites.

Journal Article↗
PubMed1998

Potential protective effect of HSCAS and bentonite against dietary aflatoxicosis in rat: with special reference to chromosomal aberrations.

Bentonite and hydrated sodium calcium aluminsilicate (HSCAS) were added at a level of 0.5% (w/w) to the diets containing 2.5 mg aflatoxins (AF) per kg diet and fed to male mature rats for 15 successive days. Aflatoxin alone significantly decreased feed intake and altered serum biochemical parameters of liver and kidney functions. Aflatoxin caused chromosomal aberrations in bone marrow cells. Bentonite or HSCAS did not alter any of the parameters measured. The addition of bentonite or HSCAS to the AF-contaminated diet diminished most of the deleterious effects of the aflatoxin. Pathological examinations of liver and kidney proved that both bentonite and HSCAS were hepatonephroprotective agents against aflatoxicosis. The cytogenetic findings demonstrated that the addition of bentonite or HSCAS to AF-contaminated diet suppressed chromosomal aberrations. These findings indicated that bentonite and HSCAS could diminished many of the adverse effect of dietary AF in rats.

Aflatoxins↗
PubMed1984

In vitro adsorption-desorption of phenethylamines and phenylimidazoles by a bentonite and a resin.

The adsorption of phenethylamines (dextroamphetamine, phentermine, mephentermine, diethylpropion), choline, and phenylimidazoles (levamisole and imazalil) was examined in vitro in aqueous solutions on bentonite and on lewatite at 25 degrees C. An ion-exchange mechanism prevails for lewatite and for bentonite up to 0.8 mEq X g-1. The organic cations are more strongly adsorbed on bentonite than on lewatite. On bentonite, the selectivity of adsorption follows the order: primary less than secondary less than tertiary phenethylamines. An interlamellar monolayer is formed. All drugs, except choline and imazalil, are adsorbed in excess of the cation exchange capacity of bentonite without observable Cl- adsorption and pH changes. Desorption is reversible for lewatite and partially irreversible for bentonite.

Adsorption↗
PubMed1995

Prevention of poison ivy and poison oak allergic contact dermatitis by quaternium-18 bentonite.

BACKGROUND: Poison ivy and poison oak are the most common causes of allergic contact dermatitis in North America. OBJECTIVE: We investigated whether a new topical lotion containing 5% quaternium-18 bentonite prevents experimentally induced poison ivy and poison oak allergic contact dermatitis. METHODS: A single-blind, paired comparison, randomized, multicenter investigation was used to evaluate the effectiveness and safety of quaternium-18 bentonite lotion in preventing experimentally induced poison ivy and poison oak allergic contact dermatitis in susceptible volunteers. One hour before both forearms were patch tested with urushiol, the allergenic resin from poison ivy and poison oak, 5% quaternium-18 bentonite lotion was applied on one forearm. The test patches were removed after 4 hours and the sites interpreted for reaction 2, 5, and 8 days later. The difference in reactions between treated and untreated patch test sites was statistically analyzed. RESULTS: Two hundred eleven subjects with a history of allergic contact dermatitis to poison ivy and poison oak were studied. One hundred forty-four subjects had positive reactions to urushiol. The test sites pretreated with quaternium-18 bentonite lotion had absent or significantly reduced reactions to the urushiol compared with untreated control sites (p < 0.0001) on all test days. When it occurred, the reaction consistently appeared later on treated than on control sites (p < 0.0001). One occurrence of mild, transient erythema at the application site was the only side effect from the quaternium-18 bentonite lotion. CONCLUSION: Quaternium-18 bentonite lotion was effective in preventing or diminishing experimentally produced poison ivy and poison oak allergic contact dermatitis.

Administration, Cutaneous↗
PubMed2006

Numerical simulation of reactive processes in an experiment with partially saturated bentonite.

Bentonites are preferred materials for use as engineered barriers for high-level nuclear waste repositories. Simulation of geochemical processes in bentonite is therefore important for long-term safety assessment of those repositories. In this work, the porewater chemistry of a bentonite sample subject to simultaneous heating and hydration, as studied by Cuevas et al. [Cuevas, J., Villar, M., Fernández, A., Gómez, P., Martín, P., 1997. Porewaters extracted from compacted bentonite subjected to simultaneous heating and hydration. Applied Geochemistry 12, 473-481.], was assessed with a non-isothermal reactive transport model by coupling the geochemical software PHREEQC2 with the object-oriented FEM simulator GeoSys/RockFlow. Reactive transport modelling includes heat transport, two-phase flow, multicomponent transport and geochemical reactions in the liquid phase, i.e. ion exchange, mineral dissolution/precipitation and equilibrium reactions. Simulations show that the easily soluble minerals in bentonite determine the porewater chemistry. Temperature affects both two-phase flow and geochemical reactions. Porosity change due to dissolution/precipitation is low during the experiment. However, changes of the effective porosity caused by bentonite swelling can be very large. The simulated results agree well with the experimental data.

Bentonite↗
PubMed2002

Removal of Ga(III) from aqueous solution by adsorption on activated bentonite using a factorial design.

The purpose of the work is to study the adsorption of gallium(III) on bentonite from aqueous solutions. The important parameters, which affect the adsorption, such as pH of solution, mass of bentonite and temperature have been investigated. The results of parameters study showed that when pH and mass of bentonite increase there was a significant increase of Ga(III) at 20 degrees C and the optimum conditions were as follows: pH of solution (2.50), mass of bentonite (3.50 g) and temperature (20 degrees C). An experimental test carried out using a factorial design 2(3) indicated that pH and mass of bentonite have a positive effect, whereas temperature has negative effect. The interaction effect between pH and mass of bentonite was an important significant factor for gallium adsorption.

Adsorption↗
PubMed2001

Experimental and modeling studies on sorption and diffusion of radium in bentonite.

The sorption and desorption behavior of radium on bentonite and purified smectite was investigated as a function of pH, ionic strength and liquid to solid ratio by batch experiments. The distribution coefficients (Kd) were in the range of 10(2) to > 10(4) ml g-1 and depended on ionic strength and pH. Most of sorbed Ra was desorbed by 1 M KCl. The results for purified smectite indicated that Ra sorption is dominated by ion exchange at layer sites of smectite, and surface complexation at edge sites may increase Ra sorption at higher pH region. Reaction parameters between Ra and smectite were determined based on an interaction model between smectite and groundwater. The reaction parameters were then used to explain the results of bentonite by considering dissolution and precipitation of minerals and soluble impurities. The dependencies of experimental Kd values on pH, ionic strength and liquid to solid ratio were qualitatively explained by the model. The modeling result for bentonite indicated that sorption of Ra on bentonite is dominated by ion exchange with smectite. The observed pH dependency was caused by changes of Ca concentration arising from dissolution and precipitation of calcite. Diffusion behavior of Ra in bentonite was also investigated as a function of dry density and ionic strength. The apparent diffusion coefficients (Da) obtained in compacted bentonite were in the range of 1.1 x 10(-11) to 2.2 x 10(-12) m2 s-1 and decreased with increasing in dry density and ionic strength. The Kd values obtained by measured effective diffusion coefficient (De) and modeled De were consistent with those by the sorption model in a deviation within one order of magnitude.

Adsorption↗