Acid Activated Bentonite Clay Research Articles

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.

Sorption of Bisphenol A from aqueous solutions by acid activated bentonite clay

Sorption of Bisphenol A from aqueous solutions by acid activated bentonite clay

Synergy of Magnetite Intercalated Bentonite for Enhanced Adsorption of Congo Red Dye

Recently, magnetic separation of adsorbent materials has attracted much attention for abatement of water pollutants. Due to the strong magnetic property and environmental beneficial behavior Fe3O4 NPs were used to modify local bentonite clay. The prepared magnetite intercalated Bentonite clay composite (Fe3O4-AC) structure and magnetic property were confirmed by powder X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The prepared Fe3O4-AC composite has shown a superior adsorption efficiency to Congo red (CR) dye over acid activated bentonite clay (AC). The enhanced adsorption of the Fe3O4 NPs intercalated in the layer of bentonite could be ascribed to the enhanced surface area and the prevention of the activated clay agglomeration. The optimum removal efficiency was analyzed using Response Surface Methodology (RSM) based Box-Benhken Design (BBD). The optimum conditions for maximum adsorption % removal were found to 94.9% at 105 min, 0.6 g Fe3O4-AC composite, 10 mg. L−1, and pH =4. The adsorption isotherms and Kinetics process were indicated that the experimental data are well fitted to Langmuir and pseudo-second-order models.

Application of activated bentonite for the removal of direct and reactive dye from aqueous solutions

The aim of this study was to determine adsorptive properties of acid activated bentonite clay for the removal of Direct Red 173 (DR 173) and Reactive Red 22 (RR 22) dyes from aqueous solutions. Raw and modified clay were characterized by the following methods: Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). The efficiency of activated clay adsorption was investigated depending on process parameters: the adsorbent dose, pH, temperature, initial dye concentration, and contact time. Experimental data were analyzed by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm as well as kinetic models of pseudo-first order, pseudo-second order and intra-particle diffusion. The process of dye adsorption was best described by Langmuir, Temkin, and Dubinin-Radushkevich isotherm (R2 > 0.97). Pseudo-second order model (R2 > 0.99) had the highest correlation with the obtained kinetic results. The positive value of ?H? indicated that adsorption of dyes by activated bentonite clay is endothermic process. The activated bentonite exhibited good regenerative ability in the 0.1 M NaOH solution. Maximum adsorption capacities of acid activated bentonite clay at 25?C for DR 173 and RR 22 dyes were 356.65 and 109.58 ?mol g-1, respectively.

Adsorption of Mordant Red 73 dye on acid activated bentonite: Kinetics and thermodynamic study

Waste-water from the textile industry is one of the major sources of contamination, causing serious health problems. The present study involves activation of bentonite clay using different acids and investigates the adsorption efficiency of acid activated bentonite clay for the removal of Mordant Red 73 from textile waste-water. Change in any functionality before and after activation was evaluated by FTIR analysis. Whereas, the surface morphological properties were observer by Scanning electron microscope. EDS analysis confirmed the leaching of Ca+2 and Mg+2 as a result of acid activation. Effects of different parameters i.e. effect of adsorbent dosage, contact time, pH and temperature and their effect on adsorption capacity were studied. Thermodynamic parameters explored the endothermic nature of adsorption. Pseudo-second order model was found to fit best for the equilibrium adsorption data.

Production of aromatic hydrocarbons from catalytic pyrolysis of lignin over acid-activated bentonite clay

Natural bentonite clay (mainly sodium-rich montmorillonite) both purified and acid activated using HCl, H2SO4, and H3PO4 acids were applied to the catalytic fast pyrolysis (CFP) of lignin. The modifications in crystalline structure and acidity of the activated clay were investigated via XRD, N2-adsorption-desorption, FTIR, TGA and NH3-TPD analysis. The activity and selectivity of the clays were evaluated for lignin conversion in down- flow micro reactor in the temperature range 500–650°0C in flowing Nitrogen (oxygen-free). The yields of high value added monocyclic aromatics such as BTX (benzene- toluene- xylenes) and naphthalene were increased by catalytic upgrading using HCl-activated bentonite clay. The selectivity for o&p-xylenes, naphthalene, and methyl naphthalene were greatly enhanced using HCl-activated bentonite in the temperature range 550–650°C. The catalyst: lignin ratio 3:1 and the nitrogen flow rate 75ml/min, at 600°C were the optimum conditions.

Microwave assisted physico-chemical modification of Bentonite clay: characterization and photocatalytic activity

The Bentonite clay was modified with different concentrations of H2SO4, forms acid activated Bentonite clay under microwave irradiation. These acid activation catalysts were characterized by PXRD, SEM, BET, FT-IR and UV Visible spectral analysis. The morphology of the catalysts was characterized by SEM analysis and was found to change particles significantly with microwave irradiation. PXRD studies revealed that the catalysts have dioctahedral phase and the average crystallite size is found to be in the range of 11-18 nm. The optical properties of the photocatalysts were investigated by UV–Vis; demonstrate the energy band gap of the catalyst. Microwave irradiation derived 2M H2SO4 catalysts exhibited excellent UV induced photocatalytic performance for the degradation of Acid orange 8(AO 8). The catalytic activities were correlated with crystallite size, band gap, morphologies and oxygen vacancies of the catalyst. Modified clay photocatalysts with high activity for environmental clean-up and it can be re-used up to 3-4 times, further used in practical applications.

Microwave assisted synthesis of Schiff base via bioplatform chemical intermediate (HMF) derived from Jatropha deoiled seed cake catalyzed by modified Bentonite clay

A novel route for Jatropha de-oiled seed cake (DSC) treatment has been developed for the synthesis of valuable intermediate (HMF) by acid activated Bentonite clay catalyst. Hydrolysis of the deoiled seed cake with different concentrations of H2SO4 activated clay (0.1M - 3M) was studied under microwave irradiation and obtained 5-HMF product was analyzed by GC-MS, UV Visible and FT-IR studies. Insitu reaction of intermediate with aniline forms solid Schiff’s base product and has been confirmed by FT-IR analysis. The prepared acid activated clay catalysts were characterized by PXRD, BET and FT-IR spectral analysis. PXRD studies revealed that the changes of phase and average crystallite size (11-18 nm). The present work directs the possibilities to provide some new insights into the synthesis intermediate from non edible de-oiled seed cake with high activity for environmental clean-up.

Enhanced removal of crystal violet by low cost alginate/acid activated bentonite composite beads: Optimization and modelling using non-linear regression technique

Adsorption feasibility of crystal violet dye (CV+) onto acid-activated bentonite clay, entrapped in a polymeric matrix of calcium alginate bead examined in this work. Operational parameters have been investigated, isotherms were analyzed using non-linear regression model and data obtained optimized by Box–Behnken model. Pseudo-nth order fits well with the kinetic data obtained, and the reaction order n was found to be between 0.925 and 3.269. Desorption tests showed that the recovery of CV+ decreased from 92.39 to 84.59% in the tenth cycle. The maximum adsorptions of crystal violet onto alginate/acid activated bentonite beads (A-AAB), alginate/bentonite beads (AB), and acid activated bentonite clay (AAB) were 582.4, 498.2 and 229mgdyeg−1 respectively. The thermodynamic parameters indicate that the adsorption process of CV+ is endothermic and more effective at high temperatures.

Preparation and evaluation of heavy metal rejection properties of polyetherimide/porous activated bentonite clay nanocomposite membrane

The acid activated bentonite clay with 1.0 to 4.0 wt% was incorporated into PEI membranes and was extensively studied for its morphology, hydrophilicity and other properties. The modified membrane exhibited an increment in porosity, hydrophilicity and a reduction in hydraulic resistance. The membranes showed rejection of 69.3%, 76.2% and 82.5% for 250 ppm of Cd(ii), Ni(ii) and Cu(ii) ion solutions, respectively.

Chemical-Vapor-Deposited Copper on Acid-Activated Bentonite Clay as an Applicable Heterogeneous Catalyst for the Photo-Fenton-like Oxidation of Textile Organic Pollutants

A heterogeneous Cu/clay catalyst was synthesized by dispersing copper onto the surface of bentonite clay through chemical vapor deposition (CVD). To resolve the copper leaching problem during the catalyst's application in aqueous reaction, a critical pretreatment step, acid activation by H2SO4, was applied to the original bentonite clay. Such manufactured Cu/clay catalyst was characterized and evaluated in the photo-Fenton-like degradation of an azo organic dye, Acid Black 1 (AB1). It was found that the acid activation process of clay could significantly reduce the leaching problem by almost 72% and improve the catalytic activity. These improvements came from the active site and the addition of sulfonate functional group on the clay surface. It was also observed that the adsorption and desorption properties of the Cu/acid-activated clay play an important role in the catalytic reaction and that its catalytic performance is better than Fe/clay at pH 7 and 9. It also has a comparable activity to that of Fe/c...

A novel heterogeneous acid-activated clay supported copper catalyst for the photobleaching and degradation of textile organic pollutant using photo-Fenton-like reaction

Copper supported on acid-activated bentonite clay was found to be an effective catalyst for the photo degradation of Acid Black 1 at pH 3.0-8.0 without significant metal leaching.