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An efficient Al-Fe cointercalated bentonite composite material (Al-Fe/Bent) which is capable of removing hexavalent chromium [Cr(VI)] from aqueous solutions was prepared. The batch experiment studies were conducted to evaluate the adsorption performance of Cr(VI) contained in aqueous solution. The XRD results showed the spacing of layers of bentonite was increased due to the aluminum and iron polycation intercalated into the layer of bentonite. The removal rate of Cr(VI) from the aqueous solution could be up 87.4% under the condition of the dosage of Al-Fe/Bent 8 g/L, pH 4, and a contact time of 60 min. The equilibrium data fitted well to the Freundlich model. The adsorption process could be well described by the pseudosecond order kinetic model.

Directly modified bentonite was obtained by directly adding modifier cetyl trimethyl ammonium bromide (CTMAB) to sodium bentonite.The modified bentonites adsorption performance to methyl orange and methylene blue was studied, and it was compared with modified bentonite prepared by classical method. The results show that directly modified bentonite has a greater and faster absorption for both methyl orange and methylene blue; the relationship between adsorption quantity and equilibrium concentration conforms to the Langmuir isotherm equation; absorption kinetics is in accordance with the secondary dynamics equation.

TiO2/bentonite composites were prepared by a sol–gel method. X-ray diffraction measurements of the samples revealed that TiO2 had intercalated into the layers of bentonite and existed in anatase phase of TiO2. Acid red 3R was used as model compounds of textile dyes in this study. The effects of operational parameters, including TiO2 content, pH, as well as catalyst dosage, on photocatalytic degradation performance were examined. The experimental results showed that the removal rate of acid red 3R can be up to 96.7% under the following conditions: the dosage of TiO2/bentonite was 2 g/L, the content of TiO2 was 30%, the pH value was 3. And the photocatalytic reaction followed pseudo-first-order kinetics models.

Na–bentonite was modified via an ion-exchange reaction with hexadecyl trimethyl ammonium bromide (CTAB). X-ray diffractometer (XRD) indicated CTAB cations had exchanged with Na+ ions in Na–bentonite and the interlayer space of bentonite was increased. Batch adsorption tests were carried out to remove phenol from model wastewater using the modified bentonite, and the effect of amount of CTAB, contact time, pH, and adding quantity of modified bentonite were evaluated. The experimental results showed that the removal efficiency of phenol can be up to 81.36% under the following conditions: the amount of CTAB was 1.5 cation exchange capacity (CEC), the dosage of organic modified bentonite was 7 g/L, the adsorption time was 60 min, and the pH value was 7. The adsorption isotherms of organic modified bentonite for phenol-based wastewater met the Freundlich adsorption equation.

Fe-pillared bentonite (Fe-Bent) was prepared by ion exchange as heterogeneous catalyst for degradation of organic contaminants in petroleum refinery wastewater. X-ray diffraction analysis showed the existence of α-Fe2O3. The effects of pH, H2O2 concentration, and catalyst dosage on the rate of lowering the chemical oxygen demand (COD) were investigated in detail. Removal efficiency of COD can be up to 92% under the following conditions: dosage of Fe-Bent 7 g L−1, pH value 3, and H2O2 concentration 10 mmol L−1. Fe-Bent showed good stability for the degradation of organics in petroleum refinery wastewater for five cycles. The adsorption of organics in wastewater onto Fe-Bent could be well described by a pseudo-second-order kinetic model.

Bentonite was used as an adsorbent for removing copper ions from aqueous solutions，and the kinetic experiments and isothermal were performed. The results showed that the bentonite on Cu2+adsorption followed the pseudo-secondary kinetic model, the high temperature was benefit for adsorption; The isothermal experimental data were fitted using Freundlich and Langmuir adsorption isotherm.