Acid-activated Bentonite Research Articles

Investigation of acid-activated iron-based bentonite materials for the oxidation mechanism of dimethyl disulfide

Due to its low olfactory threshold and high volatility, Dimethyl disulfide (DMDS) is a well-known malodorous compound in pesticides and organic synthesis. This study utilizes sodium bentonite as catalyst support, treating it with acid activation and iron-based modification to create a catalytically active bentonite material. Following modification, the bentonite maintains its fundamental structure while integrating iron ions, resulting in an expanded interlayer spacing and increased specific surface area from 60.371 m2/g to 314.539 m2/g, thereby enhancing catalytic activity. Kinetic modeling fitting demonstrates that combining iron-based acid-activated bentonite with hydrogen peroxide (H2O2) produces the most efficient oxidative system, with the highest reaction rate constant（K = 0.08038 min−1） for DMDS degradation. The best degradation effect was achieved when the ratio of Fe-H-Bent to hydrogen peroxide was 1:5, the pH was 3, and the reaction temperature was 40 °C, and the removal rate was up to 98.9%. Electron paramagnetic resonance (EPR) spectroscopy confirms that hydroxyl radicals (·OH) are this system's primary driver of oxidation. Theoretical computations and product analyses provide insight into the oxidation pathway of DMDS, showing that initial oxidation occurs at the first sulfur atom, forming an intermediate that further oxidizes to dimethyl sulfoxide and ultimately to sulfur dioxide. This research offers a practical method for the effective removal of DMDS in pesticide plants and chemical industrial parks.

Phosphate removal by acid-activated and chitosan-composite clayey soils

Phosphate is a vital nutrient for aquatic organism growth, but excessive levels can lead to eutrophication, with detrimental effects on receiving water bodies. Adsorption using clay soils can address phosphate release and has gained attention owing to its cost-efficiency and environmental friendliness. To overcome the limited phosphate adsorption capacity of clay soils due to surface charges, the combined effects of acid activation and composite formation with chitosan were investigated. Kaolin and bentonite were selected for acid activation, while chitosan varieties with low, medium, and high molecular weights were chosen for composite formation. Batch tests were individually conducted on acid-activated clay soils and composites of acid-activated clay soils with chitosan over 24 h, varying the initial phosphate concentrations. For acid activation, clay soils were treated with 6N hydrochloric acid, whereas composite formation was achieved via combination with each chitosan variant. Acid-activated kaolin and bentonite individually exhibited phosphate removal efficiencies ranging 99.8–79.8% and 97.1–47.2%, respectively. Among their respective composites, acid-activated kaolin with medium-molecular-weight chitosan and acid-activated bentonite with low-molecular-weight chitosan had the highest phosphate removal efficiencies. Therefore, in contrast to kaolin, acid activation or composite formation of acid-activated bentonite with chitosan can improve its phosphate removal efficiency.

Enhanced adsorption of phenol using graphene oxide-bentonite nanocomposites: Synthesis, characterisation, and optimisation

Wastewater treatment is crucial because it causes harm to the environment of human beings. Adsorbents are faulted by low adsorption capacity and difficult recovery due to organic pollutants. This study aims to improve adsorption capacities using bentonite and other environmentally friendly and economically feasible adsorbents. To do this, using Hammer's approach, bentonite was subjected to an acidic treatment (1.5 M H2SO4) and then hybridized with synthetic graphene oxide (GO). Integrating GO nanosheets within the interlayer of acid-activated bentonite and depositing them onto the exterior surface using a simple ultrasonic-assisted method successfully created a graphene oxide-bentonite nanocomposite. GO, and its composites (at 5 and 10 wt%) were characterized using ATR-FTIR, BET, XRD, FE-SEM, and AFM studies. The results demonstrated that GO with a single-layer thickness of 0.618 nm could be successfully fabricated. We employed energy-dispersive X-ray spectroscopy (EDX) to detect changes in chemical composition before and after phenol adsorption. It was thoroughly studied how essential factors, including adsorbent dosage, pH, agitation period, and beginning phenol concentration, affected adsorption behavior. An obvious increases of the adsorption capacities from 30.69 to 46.43 mg/g were achieved under ideal circumstances of pH 6, an 8-hour contact duration, and doses of 0.3 g and 0.2 g for GO-MB5 and GO-MB10 composites, respectively. The pseudo-second-order kinetic and Langmuir equilibrium isotherm models efficiently described the adsorption process. More notably, the synthesized adsorbents could be successfully regenerated and used without major capacity losses after six cycles. This study highlights the effectiveness of GO-bentonite nanocomposites as effective adsorbents for environmental treatment.

A novel glutaraldehyde cross-linked chitosan@acid-activated bentonite composite for effective Pb (II) and Cr (VI) adsorption: Experimental and theoretical studies

In this study, a novel glutaraldehyde cross-linked chitosan@acid-activated bentonite composite (CsG@AAB) was synthesized from crab waste, glutaraldehyde, and acid-activated bentonite (AAB). The as-obtained composite was used as an adsorbent for the efficient removal of Pb(II) and Cr(VI) from the aqueous solutions. The adsorbent was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Braeuer–Emmett–Teller (BET) analyses. The effects of factors such as initial metal ion concentration, contact time, temperature, adsorbent dosage, and pH on Pb(II) and Cr(VI) adsorption were investigated, and related adsorption parameters were determined. Characterization results indicate that chitosan entered into the bentonite interlayer. BET surface area and point of zero charge (pHPZC) of the biocomposite were 85.2 m2/g and 6.3, respectively. Both metal ions uptake was rapid while adsorption was highly dependent on solution pH. The monolayer adsorption capacity was 452.78 mg g−1 for Pb(II) and 284.14 mg g−1 for Cr(VI), respectively at 25 °C. The adsorption kinetics were explained using the PSO model. The adsorption thermodynamic process was endothermic and spontaneous. The adsorption mechanism was explained by theoretical calculations and was in good agreement with the experimental results. Physisorption (van der Waals force, pore-filling), chemisorption (both inner and outer-sphere complexes), ion exchange, electrostatic interaction, and surface precipitation were the main mechanisms of metal ions adsorption. The results of this study suggest that the CsG@ AAB composite is promising for Pb(II) and Cr(VI) uptake and can be potential adsorption for decontamination of other pollutants from real wastewater streams.

SERAPAN N, P, DAN K PADA JAGUNG MADURA-3 DI TANAH LEMPUNG LIAT BERPASIR DIAMELIORASI BIOCHAR DAN BENTONIT-TERAKTIVASI ASAM

Sandy clay loam soil in Bangkalan is a soil with a low content of nutrients, organic matter, bases, and cation exchange capacity (CEC), which inhibits the growth of maize plants. In addition, the nature of the soil causes the fertilizer to become more soluble, and the absorption of nutrients, especially potassium, is low. One of the efforts to increase potassium uptake in sandy loam soils is applying biochar and acid-activated bentonite. This study aimed to examine the effect of adding biochar and acid-activated bentonite to the nutrient uptake of maize plants in the sandy soil of Bangkalan. Biochar was prepared from maize cobs by the Kon-Tiki method; bentonite was activated by physical (200 oC) and chemical (1N H2SO4) methods. The greenhouse experiment was carried out using a completely randomized design with biochar (B) and acid-activated bentonite (T) as treatments, each with three levels, namely 0, 5, 10 t ha-1 and three replications. Soil analysis performed included pH, organic carbon, CEC and exchangeable bases, while plant tissue analysis included leaf height and area. The results showed that the combination of biochar and acid-activated bentonite significantly increased soil pH, soil exchangeable K, soil exchangeable Na, and leaf area of maize plants. A single application of biochar significantly increased soil organic C and maize plant height. The application of acid-activated bentonite significantly increased the CEC of sandy loam soils.

PATTERN OF POTASSIUM RELEASE FROM SLOW RELEASE FERTILIZER POTASSIUM CLORIDE-BENTONITE FERTILIZER

Potassium has an important role in the process of plant growth, but its presence and availability in the soil are limited, because potassium is easily lost and flows out by water. Increasing the efficiency of potassium fertilization can be pursued through the formulation of fertilizer in the form of slow-release fertilizer (SRF) using bentonite. This study aimed to determine the release of potassium in potassium chloride fertilizer into the soil after bonding with acid-activated bentonite coated with potassium chloride. The composition of the KCl fertilizer made varies with bentonite with a mass ratio (g) of 1:1; 2:1; 3:1; 4:1; and 5:1, with a percolation time of 28 days. The concentration of released potassium was determined using an atomic absorption spectrophotometer. Material characterization was carried out by FTIR. The results showed that the ratio 1:3 had the highest potassium content of 45.12% with an incubation time of 28 days. The concentration of released potassium on day 7; 14; 21; and 28 respectively (12.55±1.25)%, (28.39±1.49)%, (5.,91±0.98)%, and (70.49±1.36)% . The results of the characterization of the determination of the fungal group on SRF3 were not significantly different from that of activated bentonite. Even though there were differences in the intensity of certain peaks and changed the functional groups.

Role of Silica on Clay-Catalyzed Ozonation for Total Mineralization of Bisphenol-A.

Catalytic ozonation for the total mineralization of bisphenol-A (BPA) from aqueous solution was investigated in the presence of various silica-based catalysts such as mesoporous silica, acid-activated bentonite (HMt) and montmorillonite-rich materials (Mt) ion-exchanged with Na+ and Fe2+ cations (NaMt and Fe(II)Mt). The effects of the catalyst surface were studied by correlating the hydrophilic character and catalyst dispersion in the aqueous media to the silica content and BPA conversion. To the best of our knowledge, this approach has barely been tackled so far. Acid-activated and iron-free clay catalysts produced complete BPA degradation in short ozonation times. The catalytic activity was found to strongly depend on the hydrophilic character, which, in turn, depends on the Si content. Catalyst interactions with water and BPA appear to promote hydrophobic adsorption in high Si catalysts. These findings are of great importance because they allow tailoring silica-containing catalyst properties for specific features of the waters to be treated.

Structural morphological, and thermal properties of nano bentonite and α-Fe2O3/bentonite nanocomposite

Abstract Here, in this work, acid-activated bentonite and its nanocomposite with hematite nanoparticles were synthesized using the simple chemithermal and thermal coupling methods, respectively. The synthesized samples were investigated for morphological, compositional, structural, and thermal properties. Results suggested distortion in clay structure on acid activation and nanocomposite formation with improved thermal stability. Nanocomposite acts as a quencher for thermoluminescence and as an insulator in heat transfer reactions.

In Ukrainian

In this paper it is discussed the colloidal-chemical method of synthesis of dispersed composite bentonite-ferromagnetic powders that are stable to oxidation. It is shown that for this purpose it is advisable to use acid-activated bentonite clay with a high content of clay mineral - montmorillonite. Modified bentonite is a slightly amorphized silica product that serves as a porous matrix for crystallization of goethite α-FeOOH. The formation of goethite occurs at the centers of crystallization - particles of ferrihydrite stabilized by activated bentonite (Fh) during precipitation with an ammonia solution from a ferrum(ІІІ) hydroxide FeO(OH)×nH2O colloidal solution. In the resulting composite, goethite particles are cemented in the aluminosilicate framework of activated dispersed clay as a result of the interpenetration of the structures of the double layered hydroxide and activated bentonite. Further recrystallization of goethite with the formation of mainly magnetite and possibly maghemite in the structure of activated bentonite is provided by thermal firing of composite goethite powder with the addition of metallic iron powder. The methods of IR spectroscopy, X-ray structural analysis, electron microscopy and the study of magnetic properties showed that the obtained composite powder is environmentally friendly and exhibits the properties of a soft magnetic material. Such powders are promising for use as sorbents for environmental cleaning, as well as for biomedical purposes due to their low toxicity and high value of saturation magnetization.

PATTERN OF POTASSIUM RELEASE FROM SLOW RELEASE FERTILIZER POTASSIUM SULFATE-BENTONITE FERTILIZER

Potassium is a macro nutrient element that is needed by plants. Potassium plays a role in plant metabolism, maintains turgor, and forms stronger stems. Sadly. Potassium is easily lost through washing because it is easily soluble in water. This is what triggers plants to often experience a lack of potassium. Efficiency in the use of potassium fertilizers can be increased through the formulation of fertilizers made in the form of slow release (Slow Release Fertilizer), namely by controlling the solubility of the substance in water through fertilizer coating. The purpose of this study was to determine the potassium content obtained, the largest mass of SRF fertilizer, and the pattern of potassium release in the soil after being bound by acid-activated bentonite in the manufacture of potassium sulfate SRF. Coating of potassium sulfate with bentonite was carried out with a mass of 10 bentonite; 20; 30; 40; and 50 grams with a mass of 10 grams of potassium sulfate. Total potassium levels were analyzed by atomic absorption spectrophotometer. The results of the analysis of potassium levels obtained the levels of each SRF fertilizer with the code SRF 10: SRF 20: SRF 30: SRF 0; and SRF so respectively 4.41: 5.49: 6.06: 6.54; and 7.01 mg/g with the maximum concentration obtained from SRF sa fertilizer. Furthermore, the potassium release test was carried out using the percolation method with distilled water for potassium sulfate-bentonite SRF fertilizer with a ratio of 10:50. release test using time variation every 1 week period for 1 month. As a result, the average potassium level was obtained, namely 11.51; 38.33; 51.37; and 72.24% w/b. Based on the results of this release test it is known that potassium. experience a slow release pattern in the soil.

Enhancement Adsorption of Copper and Zinc Contaminated Water Using Highly Efficient Graphene Oxide Modified with Acid-Activated Bentonite

Enhancement Adsorption of Copper and Zinc Contaminated Water Using Highly Efficient Graphene Oxide Modified with Acid-Activated Bentonite

Optimization, and Characterization of Acid-Activated Bentonite

Optimization, and Characterization of Acid-Activated Bentonite

Eco-efficient treatment of hazardous bauxite liquid-residue using acid-activated clays

The alumina industry requires a material capable of reducing the high levels of iron and alkalinity in bauxite liquid-residue in an eco-efficient manner while producing fewer by-products. This study looked at the efficacy of acid-activated kaolin (AAK) and acid-activated bentonite (AAB) in reducing the high pH value and iron content of bauxite liquid-residue in a single treatment step. The bauxite residue, AAB, and AAK were characterised using XRD, XRF, and FTIR techniques. A batch adsorption study with varying contact times and adsorbent types was conducted, and the results were analysed using adsorption kinetics and isotherm studies. The results showed that AAK and AAB could effectively remove 88% to 94% of the total iron in the bauxite liquid-residue. Similarly, the initial pH value of the bauxite liquid-residue (9.93 ± 0.13) was reduced by about 3.32% with AAK and 4.53% with AAB, respectively. Thus, batch adsorption studies revealed that adsorption capacity was strongly pH dependent, and the type of adsorbent had an effect on the reduction of iron and pH value in the bauxite liquid-residue. The AAB was found to be more effective than AAK in lowering the high pH value and iron content of the bauxite liquid-residue.

Synthesis of Patchouli Esters from Patchouli Oil in the Presence of Homogeneous and Heterogeneous Catalyst

Patchouli alcohol was isolated from patchouli oil by fractional distillation under reduced pressure. Patchouli esters were then prepared from isolated patchouli alcohol via esterification reaction in the presence of homogeneous (concentrated hydrochloric acid) and heterogeneous (acid-activated bentonite) catalysts. Fractional distillation under reduced pressure was carried out by heating patchouli oil under a pressure until 0 mmHg. Esterification reaction was carried out by heating patchouli alcohol with propionic acid in the presence of an acid catalyst at 100-110 for 3 h The products were characterized using FTIR and GCMS spectrometers. The esterification reaction with HCl 37% and bentonite catalysts produced patchouli propionate in 26% and 21% yields, respectively.

Acid-activated bentonite blended with sugarcane bagasse ash as low-cost adsorbents for removal of reactive red 198 dyes

Abstract The present research work investigated the removal efficiency of acid-activated bentonite blended with a sugarcane bagasse ash (SCBA) adsorbent for the removal of reactive red 198 (RR198) from a synthetic dye solution. The effect of the adsorption parameters of bentonite on SCBA blending ratio, dye solution pH, adsorption contact, adsorbent dosage, and initial dye concentration was investigated, and the parameters were optimized for maximum RR198 removal from the synthetic dye solution. At an optimum condition of 1:1 bentonite to the SCBA blending ratio, a solution pH of 2, 3.7 g/L of adsorbent dosage, and 15 mg/L of initial dye concentration 150 min of adsorption time, the properties of adsorbents such as adsorbent specific surface area, crystalline phase structure, functional groups, and surface morphologies of the adsorbents were investigated. At optimum conditions, 97% RR198 removal efficiency of the adsorbent was achieved. In order to determine adsorption kinetics and isotherm models, different adsorption models were employed. It was observed that the adsorption of the RR198 dye into the acid-activated bentonite blended with the SCBA adsorbent was represented well by the Langmuir isotherm model and the adsorption kinetics order was found to be the pseudo-second order.

Acid Activated Bentonite-La Crosslinked Sesbania Gum Beads for Efficient Congo Red Adsorption

In this study, to recycle acid activated bentonite (AAB), novel hybrid beads were prepared from AAB and sesbania gum (SG), which might be an efficient adsorbent for removing an anionic dye Congo red (CR). To gain the greatest adsorption conditions of AAB-SG-La beads, experiments were carried out to evaluate the effects of initial pH value, AAB-SG-La beads dosage on CR removal. The optimal pH value of AAB-SG-La beads for CR elimination was in the range 4.0 ~ 8.0, which can broaden the applications of beads. In addition, the adsorption isotherm datas were consistent with the Langmuir adsorption model and adsorption kinetics conformed to the pseudo-second-order model. Furthermore, the adsorption capacity of CR was 588 mg/g, which revealed a superior adsorption capacity to other materials used as sorbents for CR. This work accredits that AAB-SG-La beads have the ability to remove anionic dye as an economical adsorbent.

Low-cost structured alginate-immobilized bentonite beads designed for an effective removal of persistent antibiotics from aqueous solution

The removal of persistent antibiotics from the water bodies can be quite challenging. The present study deals with the removal of doripenem, one of the most stable and persistent antibiotics, from aqueous solution via adsorption technique using the low-cost structured alginate-immobilized bentonite (Alg@iB) beads which can be easily recovered after the process. Alg@iB possesses a porous interior and higher basal spacing compared with the acid-activated bentonite (iB). Its adsorption/desorption isotherm corresponds to type IV IUPAC classification and H4-type hysteresis loops, implying the presence of slit- or plane-shaped pores. The influences of four independent adsorption parameters, e.g., pH, initial doripenem concentrations (md), temperature (T), and Alg@iB loading (mc), on the removal rate of doripenem (Yd) are investigated. The maximum Yd (95.8% w/w) is obtained at pH = 5, mc = 1.4% w/v, T = 50 °C, and md = 250 mg/l. The study suggests that the adsorption of doripenem is spontaneous and endothermic. Further analysis using the multi-linear intra-particle diffusion (IPD) model indicates that the rate-governing step in this adsorption process is the physical diffusion from the bulk solution to the boundary layer of Alg@iB. However, the mechanism study also considers the chemical hydrogen binding between the hydronium ions of Alg@iB and hydroxyl groups of doripenem as one of the driving forces that promote adsorption. Alg@iB shows good reusability with Yd > 90% w/w up to five adsorption cycles. Based on the study, the Alg@iB beads exhibit excellent affinity to doripenem, indicating that an effective doripenem removal can be achieved using this sorbent material.

Study of Hydrolysis Process from Pineapple Leaf Fibers using Sulfuric Acid, Nitric Acid, and Bentonite Catalysts

The hydrolysis process of pineapple leaf fibers has been carried out using sulfuric acid, nitric acid, bentonite catalyst, and activated bentonite catalyst. The sugar content of the hydrolysis product was identified using the phenol-sulfuric acid method by UV-Visible spectrophotometry. The disposal of pineapple leaf is a big problem even though it has high cellulose content (70–80%) and very promising to produce sugar by hydrolysis process. The purpose of this experiment was to determine the effectiveness of homogeneous and heterogeneous catalysts related to sugar levels in pineapple leaf fiber. The variables in this study were the sampling time during the hydrolysis process at a temperature of 100 °C and the addition of homogeneous and heterogeneous catalysts. The homogeneous catalysts were sulfuric acid and the nitric acid meanwhile heterogeneous catalyst was thermally activated bentonite and acid-activated bentonite. The results obtained highest sugar content reached at 150 minutes using chemical activated bentonite catalysts at 6.459 g/L and the addition of catalysts affected sugar yields, speed up the reaction, bentonite as a good catalyst, and gave good prospect for ethanol production in further process. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Preparation and Characterization of Acid-Activated Bentonite with Binary Acid Solution and Its Use in Decreasing Electrical Conductivity of Tap Water

The characteristics of acid-activated raw bentonite (RB) activated with binary acid solutions sulfuric acid + nitric acid, nitric acid + phosphoric acid, and phosphoric acid + sulfuric acid, at a concentration of 5 mol/L (denoted as 5-SN, 5-NP, and 5-PS), were evaluated. Moreover, its application for improving the electrical conductivity in tap water was demonstrated. Acid activation induced the partial destruction of RB; subsequently, there was a significant release of sodium ions from the RB. In addition, the specific surface area and pore volume of 5-SN, 5-NP, and 5-PS were higher than those of RB. Next, the electrical conductivity when using RB increased with adsorption treatment because sodium ions were released from the RB. However, the electrical conductivity significantly decreased with adsorption treatment when using acid-activated RB. Specifically, magnesium ions, calcium ions, and potassium ions were removed into 5-SN, 5-NP, and 5-PS, and sodium ions were not released from the RB simultaneously. The removal percentage of the electrical conductivity using 5-SN, 5-NP, and 5-PS was approximately 31% to 36%. The results indicated that employing acid-activated RB with a binary acid solution is a useful method for decreasing the electrical conductivity in tap water.

Characteristics of Raw and Acid-Activated Bentonite and Its Application for Improving Electrical Conductivity of Tap Water.

This study aimed to investigate the characteristics of acid-activated bentonite by focusing on its capability of improving the quality of tap water used during wire electrical discharge machining. Raw bentonite (RB) was activated using sulfuric acid, nitric acid, and phosphoric acid solutions with concentrations of 1, 5, and 10 mol/L, respectively. Scanning electron microscopy images, specific surface area, pore volume, cation exchange capacity, X-ray diffraction patterns, and binding energy of RB and acid-activated bentonites were also evaluated. The specific surface area and pore volume of acid-activated bentonites exceeded those of RB. Conversely, the cation exchange capacity of acid-activated bentonites exhibited an opposite trend. The electrical conductivity of tap water was decreased significantly due to bentonite activated with sulfuric acid, nitric acid, and phosphoric acid solution (removal percentage of approximately 31-39%), as compared to that due to RB. Therefore, the relationship between electrical conductivity and the removed concentration of anion/cation ions was evaluated; the correlation coefficient was -0.950 for the experimental condition in this study. Additionally, the amount of magnesium, calcium, potassium, and sodium ions were decreased after the treatment. These results indicated that acid-activated bentonite can be produced from RB via acid activation and that it can be used to decrease electrical conductivity of tap water.