Natural Bentonite Research Articles

Active sites regulation and adsorption performance of Al-pillared bentonite for the removal of lead from aqueous phase

Developing an environmentally friendly adsorbent with high adsorption capacity and economic benefits is crucial for the treatment of lead-contaminated wastewater. In this study, active clay (A-bent) and Al pillared acid-activated clay (A-AlPILC) were prepared using natural bentonite as the carrier via acidification and pillar-supported technology. The samples were characterized by X-ray diffraction (XRD), N2 adsorption-desorption experiments, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence spectrometer (XRF). The results showed that the amended clay exhibited an increase in specific surface area (SSA) from 39.37 m2/g to 175.28 m2/g and 245.42 m2/g compared to raw bentonite. The interlayer spacing and total pore volume rose respectively. The adsorption technique achieved an impressive removal rate of 90.6 % for Pb(II). Adsorption data were fitted by adsorption kinetics and adsorption isotherm model. Based on the response surface method (RSM), and analysis of variance (ANOVA) showed that the influence of these variables was significant. The simulation of lead ions showed that the acidic functional groups and ligands promote adsorption more than they inhibit it. Using the density function theory (DFT) calculation, the bentonite cycle model was established to demonstrate the interaction between bentonite and lead, with a binding energy of −0.369 eV. Similarly, the density and energy band structure of the state were computed to explore the mechanism of heavy metal adsorption by clay minerals.

Mechanism of tetracycline sorption on carbon-bentonite

Antibiotics increased industrial production is the reason of their occurrence in wastewater, soils, groundwater, and drinking water. In this regard, treating the environment for pharmaceuticals is one of the urgent environmental challenges. Synthesis of adsorbents using different types of raw materials by the methods of mechanochemical activation makes it possible to significantly increase their sorption capacity due to the accumulation of various kinds of defects in the crystal structure of the adsorbent. We obtained the bentonite-carbon composite using roller-ring vibratory mill with coal-bentonite ratio of 30 : 70 and 50 : 50. However, the nature of the interaction between carbon and bentonite correlates with changes of surface area and porosity. The porous structure parameters of the samples show the mechanochemical activation of the mixture involves their components interactions. The authors studied the structural and chemical changes during the modification of bentonite with activated carbon by analysing the vibrational spectra of carbon, initial, and modified aluminosilicate samples. According to infrared spectroscopy of adsorbents, absorption bands characteristic of Si-O-C bond vibrations occurred. The paper investigates the sorption capacity of mechanochemically modified natural clay mineral Dash-Salakhli bentonite towards tetracycline hydrochloride. Research investigates the kinetics of the process and rapid sorption of tetracycline. The paper provides possible mechanisms of chemisorption due to donor-acceptor interaction and ion-exchange processes.

Removal process of an industrial dye using a biosorbent: characterization, kinetic, equilibrium, and thermodynamic studies

Adsorption-based removal is a highly efficient environmental phenomenon employed to eliminate various dyes, such as crystal violet (CV), which is prevalently used in the textile industry and subsequently discharged into natural ecosystems. This study aims to utilize natural bentonite clay sourced from Algeria for the extraction of cationic dye (CV) from wastewater. The characterization of the bentonite was conducted using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). Evaluations assessed the impact of various parameters including pH, stirring time, temperature, and initial dye concentration on the adsorption efficiency. Optimal conditions for the maximal adsorption of CV were determined to be 430.18 mg g-1 at an adsorbent-to-dye solution ratio of 1 g L-1, pH 11.06, an equilibrium time of 40 minutes, and a temperature of 40°C. The adsorption kinetics were best described by the pseudo-second-order model, while the Freundlich isotherm model aptly described the adsorption isotherms. Thermodynamic parameters underscored the spontaneous and exothermic nature of the crystal violet removal process using raw bentonite. This research provides novel insights into the effective removal of a cationic dye from water and wastewater using Algerian bentonite clay.

Removal of Pb(II) ions from aqueous solutions using natural and HDTMA-modified bentonite and kaolin clays

This work focused on the removal of Pb(II) from aqueous solution using kaolin and bentonite clays modified with hexadecyl trimethyl ammonium bromide (HDTMA). The clays were characterized using a zetasizer, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Brunauer-Emmet-Teller (BET), Fourier-transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA). Factors that influence the adsorption of Pb(II) from aqueous solution, namely pH, contact time, adsorbent mass, ionic strength, temperature and initial Pb(II) concentration were investigated. The results show that HDTMA was successfully incorporated into the kaolin and bentonite clay structures. The most favorable parameters for the adsorption of Pb(II) ions onto all adsorbents was pH of 6.0, temperature of 25 °C and adsorbent mass of 200 mg. Adsorption isotherms and kinetic studies showed that the adsorption of Pb(II) onto kaolin, bentonite and organobentonite clays followed the Langmuir isotherm and pseudo-first order kinetic model, while the adsorption onto organobentonite was better explained by the Freundlich isotherm and pseudo-second order kinetic model. Maximum monolayer adsorption capacity of organobentonite, calculated from the Langmuir model was 18.75 mg/g, which is higher than that obtained for the unmodified bentonite (14.71 mg/g); while for organokaolin it was 2.26 mg/g, which is less than that of the unmodified kaolin (4.19 mg/g). Thermodynamic studies showed that the reactions were exothermic and unfavoured at high temperatures. The adsorbents also showed good removal efficiency for up to four regeneration cycles.

Adsorption of Bichromate and Arsenate Anions by a Sorbent Based on Bentonite Clay Modified with Polyhydroxocations of Iron and Aluminum by the "Co-Precipitation" Method.

The physicochemical properties of natural bentonite and its sorbents were studied. It has been established the modification of natural bentonites using polyhydroxoxides of iron (III) (mod.1_Fe_5-c) and aluminum (III) (mod.1_Al_5-c) by the "co-precipitation" method led to changes in their chemical composition, structure, and sorption properties. It was shown that modified sorbents based on natural bentonite are finely porous (nanostructured) objects with a predominance of pores of 1.5-8.0 nm in size. The modification of bentonite with iron (III) and aluminum compounds by the "co-precipitation" method also leads to an increase in the sorption capacity of the obtained sorbents with respect to bichromate and arsenate anions. A kinetic analysis showed that, at the initial stage, the sorption process was controlled by an external diffusion factor, that is, the diffusion of the sorbent from the solution to the liquid film on the surface of the sorbent. The sorption process then began to proceed in a mixed diffusion mode when it limited both the external diffusion factor and the intra-diffusion factor (diffusion of the sorbent to the active centers through the system of pores and capillaries). To clarify the contribution of the chemical stage to the rate of adsorption of bichromate and arsenate anions by the sorbents under study, kinetic curves were processed using equations of chemical kinetics (pseudo-first-order, pseudo-second-order, and Elovich models). It was found that the adsorption of the studied anions by the modified sorbents based on natural bentonite was best described by a pseudo-second-order kinetic model. The high value of the correlation coefficient for the Elovich model (R2 > 0.9) allows us to conclude that there are structural disorders in the porous system of the studied sorbents, and their surfaces can be considered heterogeneous. Considering that heterogeneous processes occur on the surface of the sorbent, it is natural that all surface properties (structure, chemical composition of the surface layer, etc.) play an important role in anion adsorption.

Reflection coefficient of a natural sodium bentonite in aqueous mixed electrolyte solutions: positive and negative anomalous osmosis

A natural sodium bentonite was tested in the laboratory to measure its reflection coefficient, ω, in equilibrium with mixed aqueous solutions of sodium chloride (NaCl) and potassium chloride (KCl), with the aim of assessing the relative contribution of chemico-osmosis and diffusion induced electro-osmosis to the non-hydraulic component of the liquid flux in the presence of two cationic species, which diffuse at different rates in the pore solution. The former chemico-osmotic contribution is only related to the ionic partition effect in the bentonite pores, and causes ω to vary in the 0 to 1 range, whereas the latter electro-osmotic contribution is controlled by the diffusion potential, which spontaneously builds up across the bentonite layer in response to the different aqueous-phase diffusion coefficients of the ionic species. The theoretical interpretation of the obtained test results demonstrated that chemico-osmosis was the major contribution to ω when the testing solutions only comprised KCl. However, significant deviations in the values of ω from those expected for pure chemico-osmosis were observed for mixtures of NaCl and KCl, with both negative ( ω = −1.234) and positive ( ω = 1.040) anomalous values of the reflection coefficient, resulting from the enhanced influence of diffusion induced electro-osmosis.

Complex means for the prevention of combined mycotoxicosis of birds

Poultry meat is in great demand in the food market. The main method of producing poultry meat is raising broilers. The growth of broiler chickens is largely determined by balanced feeding. In recent years, poultry diets have increasingly included biologically active additives with a pronounced positive effect on the viability and productivity of poultry. In this regard, the purpose of our study was to study the effectiveness of the use of complex preventive measures for experimental combined T-2 and aflatoxicosis in broiler chickens, taking into account the clinical, hematological status and organ weight. Broiler chickens were divided into 4 groups: birds of the first group (biological control) received only complete feed that did not contain mycotoxins; the second group served as a toxic control (feed was contaminated with a mixture of mycotoxins); the third group received a basic diet contaminated with a mixture of mycotoxins with the addition of complex agent No. 1 (plant glucans, hepatoprotector, vitamins E and C, immunostimulant); the fourth group is the main diet, contaminated with a mixture of mycotoxins with the addition of complex agent No. 2 (natural mineral bentonite, succinic acid, immunostimulant, vitamin A, probiotic based on bifidobacteria and lactobacilli). The duration of administration of toxins and prophylactic agents is 21 days. Complex agents were administered at a dose of 0.25% of the diet. As a result of the use of these agents, a decrease in the toxic load on the body was noted, which was manifested by an improvement in the clinical condition of chickens and normalization of morphological blood parameters. These results suggest that the complexes can be an effective means for reducing the toxic effects of mycotoxins on the body of broiler chickens with combined mycotoxicoses.

Elaboration and characterization of a natural bentonite-poly(ethylene glycol) composite: Development of an exact theoretical study in function of the polymer-density

The first aim of this work was a systematic experimental and theoretical study of the basal-spacing and characteristics of X-rays diffraction-peaks (positions, intensities, crystallites size...), versus the polymer-density, for a natural bentonite-poly(ethylene glycol) composite. The natural bentonite was extracted from a deposit located in Eastern Rif chain of Morocco (near Nador-city). The basal distance and diffraction-peaks characteristics were measured using X-Rays Diffraction (XRD) method, first, for raw bentonite, and second, for bentonite-poly(ethylene glycol) composites. In particular, measurements reveal the existence of a series of montmorillonite-phases (crystallites) of different sizes within the composites. Afterwards, we have developed a powerful theoretical approach based on Renormalization Theory, and obtain exact scaling relations for the physical quantities of interest. We have compared our theoretical predictions with our experimental data dealt with the considered natural bentonite-poly(ethylene glycol) composites, and found that theory and experiment are in good agreement. Also, as a complementary experimental study, we achieved a detailed analysis of pure PEG, natural bentonite and Bentonite-PEG composites using the so-called Fourier Transform Infrared Spectroscopy (FTIR) tool. A comparison between these complexes show that the polymer-density affects drastically the stretching and bending vibration modes.

High surface area inorganic minerals show promise in protecting carbon from soil organic amendments

Protecting soil organic compounds could assist with global efforts to mitigate climate change, as well as improve soil health. Recent research has indicated that high surface area inorganic minerals (HSAIMs) can protect soil organic matter (OM). We evaluated if adding HSAIMs to soils can protect carbon from common organic inputs added to fallow soils prior to planting. Four added HSAIMs were investigated – two manufactured zeolites, one natural zeolite and bentonite clay – along with a carbon-rich (peat moss) and carbon-poor (composted cow manure) OM source. The added HSAIMs and organic sources were incorporated into a microbially active (clayey Vertisol) and inactive (sandy Arenosol) soil at application rates of 20 tonnes.ha–1 for the minerals and 60 tonnes.ha–1 for the organics. The treatments were incubated for three months under laboratory conditions and were subjected to continuous wetting-drying cycles. Peat moss resulted in higher organic carbon (Corg) and OM losses than cow manure. Moreover, the addition of HSAIMs to the Peat Moss+Arenosol treatments appeared to slightly enhance these losses, albeit not significantly (p>0.05). Carbon/nitrogen (C/N) ratios revealed that the Arenosol treatments were depleting soil N to access the carbon provided by the peat moss. For all other treatment combinations, the addition of HSAIMs promoted greater retention of Corg (p<0.05 in one treatment combination) and OM (p<0.05 in four treatment combinations), relative to the controls. Modelling carbon balances using OM data was more effective than using direct Corg values, due to strong Corg measurement variance. Modelled Corg data revealed the added HSAIMs achieved up to 25 % carbon protection, with the manufactured zeolites particularly effective. The study shows promise for added HSAIMs to protect carbon released from decomposing organic amendments added to fallow soils. However, addition of these minerals to N-limited soils receiving carbon-rich amendments might accelerate carbon losses.

Assessment of Natural Bentonite Efficacy for Dye Removal in Textile Wastewater Treatment : Implication for Mitigating River Citarum Pollution

Textile industries contribute significantly to the economy but release harmful pollutants into the environment, especially rivers. The effluent from the textile industry contained toxic dyes that can harm the river ecosystem. Several studies have been conducted to reduce toxic dyes in a river system using bentonite as an adsorbent to reduce river pollution effectively. However, the effectiveness of bentonite still needs to be tested again using textile liquid waste that has not gone through any waste processing at all. Citarum is one of the main rivers on Java Island, which suffers from textile effluent, especially azo dyes which are toxic, mutagenic and carcinogenic which can harm the aquatic ecosystem. Therefore, this study aims to implement natural bentonite as an adsorbent to remove dyes from textile wastewater. We performed a laboratory test to adsorption on bentonite and textile wastewater considering the variation of adsorbent weight of 10 g and 20 g in 100 mL of textile wastewater stirred in an Erlenmeyer flask at room temperature for 0-300 minutes. The initial concentration of textile wastewater used was 10%, 30%, and 50%. We found that the maximum dye removal efficiency was 91.25% with 10% initial concentration treatment, 20 g adsorbent weight, and 60 minutes contact time. Longer contact time will increase the removal efficiency and adsorption capacity, while higher adsorbent dosage will decrease the concentration of dyes in wastewater. Efficient textile wastewater treatment has improved water quality, effectively meeting river water quality standards and environmental regulations.

Potential of Local Natural Bentonite Impregnated with N-TiO2 to Degrade Methylene Blue Using Photocatalytic Process

Potential of Local Natural Bentonite Impregnated with N-TiO2 to Degrade Methylene Blue Using Photocatalytic Process

Design of activated bentonite-based catalysts for the esterification of residual free fatty acids from palm oil

Bentonite, a readily available and abundant natural mineral, serves as a cost-effective catalyst for esterifying free fatty acids (FFAs). In this study, an economical method was developed to enhance the catalytic activity of Chocolate bentonite (Ca-CB) from Paraíba, Brazil, for the methyl esterification of distilled deodorized palm oil (DDPO), an agro-industrial by-product containing approximately 84 % FFAs. Raw bentonite and activated material were characterized using various techniques, including nitrogen physisorption, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)/differential thermogravimetry (DTG), scanning electron microscopy (SEM), and acid-base titration. The highest conversion rate of 93 % was achieved using H-Ca-CB in the esterification of DDPO, surpassing H-Na-Ca-CB (91 %) and the commercially available K-10 catalyst (81 %). Furthermore, H-Ca-CB maintained superior catalytic activity (over 75 %) even after four reuse cycles, outperforming autocatalysis (34 %). Kinetic studies of the transesterification process indicated that the pseudo-first-order model was the most suitable, with an activation energy of 27.40 kJ mol–1. These findings underscore the effectiveness of natural bentonite in catalytic synthesis, attributed to its enhanced textural properties and surface acidity.

Syngas Production Through Non Catalytic Gasification of Empty Fruit Bunch and Catalytics Using Natural Bentonite

Syngas Production Through Non Catalytic Gasification of Empty Fruit Bunch and Catalytics Using Natural Bentonite

Adsorption of Cd and Mn from neutral mine effluents using bentonite, zeolite, and stabilized dewatered sludge

This study aimed to investigate the adsorption efficiency of Cd and Mn using natural sorbents—bentonite, zeolite and stabilized digested dewatered waste sludge. The main contributions of the scientific article are in adding to the scientific knowledge of the use of natural and waste sorbents in the removal of heavy metals from neutral mine effluents. Current studies mainly focus on metal removal by sorption using natural sorbents from acid mine drainage. This study investigates sorption in neutral mine drainage. The efficiency of the sorption process was evaluated using the following parameters: efficiency (%) of metal ion removal, Freudlich and Langmuir adsorption isotherm constant. The AES–ICP method (atomic emission spectrometry with inductively coupled plasma) was used for the initial metal analysis of the materials used. The atomic absorption spectrometry (AAS) method was used for the analysis of Cd and Mn in the sorption process. The maximum efficiency of Mn removal by bentonite at the end of the test was approximately 90%. The removal of Mn by zeolite was considerably lower—about 20% compared to the use of sludge—80%. Based on the sorption efficiency, the sludge was suitable for sorption. Much higher levels of Cd sorption were achieved using sludge compared to using natural bentonite and zeolite. The main novelty of the work lies in the sorption of metals using dewatered digested sludge. Previous studies have focused on metal sorption using activated sludge. Most previous studies focused on sorption from acid mine drainage. The novelty of this study is that we focused on the sorption of neutral mine drainages, which are typical for the location we are monitoring.

INVESTIGATION OF ADSORPTION OF BENTONITE SAMPLES WITH IONOGENIC OLIGOMER BY PHYSICO-CHEMICAL METHODS

The adsorption process of natural and modified Co+2-, Ni+2-bentonite samples taken from Dash-Salahli field with ionogenic oligomer modifiers was carried out and studied by x-ray and infrared spectral analysis methods. Important components that ensure the stability of bentonite suspensions are polymers, ions and surfactants. The main goal of the work is to obtain an organic mineral sorbent using an ionogenic oligomer modifier to stabilize polymer-dispersed systems. The most suitable surfactants are substances with a hydrophilic and hydrophobic statistical distribution in the molecule. The prepared sorbent has both cationic and anionic properties and can adsorb various harmful organic substances. As a result of the research, certain changes were observed in the structure of the sorbents. Depending on the ionic radii of substituted metal ions in natural bentonite, weak, medium. strong intensities are observed

The effect of calcination on natural calcareous bentonite for Mn and Fe adsorption in aqueous solution

Mn and Fe are common metallic elements found in wastewater. In high concentration these elements can cause environmental and health risks. This study was conducted to examine the improvement of natural calcareous bentonite (NCB) adsorption capacity on Mn and Fe in aqueous solution after high-temperature calcination. The NCB sample was prepared in three conditions: untreated, calcined at 200 °C and 800 °C. The Mn adsorption test showed the calcined sample at 200 °C had no significant differences uptake to the untreated with an increase in pH from 3 to 7 in one hour and reached the equilibrium in 24 hours. Disparately, the calcined sample at 800 °C showed much higher Mn uptake, immediate equilibrium, and an extreme increase in pH from 3 to 11 just in one hour. The Fe adsorption test for three sample conditions exhibited immediate Fe uptake and equilibrium within just one hour, with no differences in Fe uptake. However, the pH in equlibrium time had different increase. The untreated and the calcined sampel at 200 °C had an increase pH from 3 to 7 while the calcined sample at 800 °C had an increase pH from 3 to 11.

Natural Moroccan bentonite clay as an adsorbent for nutrient removal from synthetic leachate: Performance and evaluation

To ensure the protection of public health and environmental integrity, while also meeting effluent regulation standards, it is critical to treat leachate due to its composition of hazardous substances before it is introduced into the environment. Pollution from leachate is characterized by several indicators, including COD, BOD5, conductivity, pH, and the presence of various ions such as ammonium, nitrite, nitrate, chloride, and orthophosphate. This research examines the adsorption properties of natural bentonite clay from Nador, located in eastern Morocco, for its efficacy in removing ammonium, nitrate, and nitrite ions from synthetic leachates. We present the outcomes of adsorption experiments utilizing bentonite clay to eradicate these nitrogen-based ions from artificial leachate, using UV adsorption spectroscopy for the measurement of ion concentrations before and after adsorption. Additionally, the study evaluates the efficiency of bentonite clay in adsorption, identifying the optimal amount of clay required for effective pollutant reduction. Our results demonstrate that, following a 24-hour mixing period, the adsorption rates for ammonium, nitrate, and nitrite ions were roughly 48%, 40%, and 85% at 35 °C, and 40%, 15%, and 25% at 25 °C, respectively. These findings suggest that modulation of agitation duration and temperature can significantly improve adsorption efficiency, with elevated temperatures facilitating shorter reaction times and higher adsorption rates for nitrogen ions. Ultimately, the research confirms the potential of bentonite clay as an effective medium for the removal of these contaminants from landfill leachate, offering a promising approach for enhancing environmental sustainability.

Natural rubber latex as a potential additive for water-based drilling fluids

The environmental hazards and "carbon footprint" of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals. This paper explored for the first time the interaction mechanism between natural rubber latex (NRL) and bentonite suspensions (BTs) through a series of characterization experiments, as well as the potential applications in water-based drilling fluids (WBDF). The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient (k) and flow index (n) of BTs, and enhance the shear thinning performance of BTs as pseudo-plastic fluids. In addition, 0.5 w/v% NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles, but also facilitated the compatibility of pressure loss and flow efficiency. The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles, and optimize the particle size distribution and flow resistance of WBDF under the "intercalation-exfoliation-encapsulation" synergistic interaction. Moreover, NRL can improve the rheological properties of WBDF at high temperatures (<150 °C), and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake, which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

INFLUENCE OF рН AND Ca&lt;sup&gt;2+&lt;/sup&gt; IONS ON CHEMICAL COMPOSITION AND SORPTION OF &lt;sup&gt;137&lt;/sup&gt;Cs BY CHERKASY BENTONITES (UKRAINE)

The safety of near-surface and deep radioactive waste storage facilities is based on a system of engineered and natural barriers. Significant degradation of the engineered barrier system composed of cemented waste matrixes covered by cement mixture, concrete compartments, and structures at the basement of the storage facility may cause radionuclide transfer from the facility to groundwater. Mixing of the cement and concrete with water leads to the formation of several various hydration products with subsequent leaching of Ca2+ ions and formation of hydroxyl ions (OH-), which affects the alkalinity of the water environment and the sorption properties of bentonite, as a component of the engineered barrier at the basement of near-surface facilities. The article presents the results of an experimental study of the influence of Ca2+ ion concentration and pH of the model solution (similar to groundwater composition at Vector Site in Chornobyl Exclusion Zone) on the elemental composition and sorption properties of natural (NB) and Na-modified (PBA-20) bentonites from the Cherkasy deposit concerning 137Cs at the Solid : Solution ratio of 1 : 100. Geochemical modeling suggests that addition of CaCl2 to test solution and resulting alkaline pH leads to precipitation of solids, mainly oxides, hydroxides, Fe oxyhydroxides (hematite, goethite, limonite), and Ca carbonates (calcite, aragonite, dolomite). Their role in Cs adsorption was evaluated. The concentration of structural elements (Si, Al) in bentonites practically does not change with Ca2+ ion concentration increase in the model solution, demonstrating the bentonite structure’s stability under these conditions. At the same time, an increase in the Ca concentration and a decrease in the Na concentration was found in the ion exchange complex of the bentonites if compared to the initial natural bentonite. This results in the transformation of Na-modified bentonite from Na, Ca-form to Ca, Na-form. The total sorption capacity of NB and PBA-20 bentonite concerning Cs+ ions at increased concentrations of Ca2+ ions and pH of the solution slightly decreases, though retaining high values of the degree of absorption (&gt; 90 %). The total adsorption of Cs+ ions on NB and PBA-20 bentonites from model groundwater with the addition of CaCl2 from 16 to 960 mg/dm3 and increase of рН from 7.4 to 11.8 decreases with the increase in ionic strength, in particular, due to competition with Са2+ and Na+ ions. NB and PBA-20 bentonites of the Cherkasy deposit remain a reliable component of the liner at the repository basement owing to their main functional property – high absorption capacity for 137Cs, which is an important dose-forming radionuclide of short-lived low- and medium-level waste.

The Potential of Bentonite as a Low-cost Adsorbent for the Removal of Heavy Metal Ions from Multicomponent Aqueous Systems of the Galvanic Industry

Waste water in the galvanic process contains high concentrations of heavy metals that pose a direct danger to humans and the environment. Conventional methods for their removal are quite expensive and generate a large amount of waste. The development of new and improvement of existing methods for the removal of heavy metals from galvanic wastewater are the subject of many studies. Compared to other purification methods, the adsorption is becoming an increasingly popular method of wastewater purification, especially if the adsorbent is cheap, easily available and does not require any other treatment before use. Therefore, the aim of the work was to investigate the possibility of using natural bentonite for the removal of heavy metal ions from multi-component water systems of the galvanic industry. For this purpose, the physico-chemical characterization of natural bentonite was performed, and then the influence of pH value, time and temperature on the adsorption efficiency was examined. The results of adsorption showed that natural bentonite can be used as an adsorbent for the removal of heavy metal ions from waste galvanic waters, and that at pH 5 it achieves the maximum removal efficiency for Cu(II):Cr(III):Ni(II) ions in the percentage ratio 100 : 99.990 : 99.998. The results showed that the highest removal efficiency for Cu (II) ions was achieved in the first 10 minutes, and 20 minutes for Cr (III) and Ni (II) ions. The maximum efficiency of Cu (II) removal was achieved at all temperatures, while for Cr (III) 99.99% and Ni (II) 100% maximum efficiency was achieved at 35°C, which indicates that the adsorption process is endothermic. The experimental results of the adsorption of Cu (II) metal ions are in good agreement with the Langmuir and Freundlich theoretical models, while for Cr (III) and Ni (II) ions they are in better agreement with the Langmuir adsorption model.