This research by the researcher of the College of Chemistry and Chemical Engineering of Guangxi University, discussed the paper on the adsorption performance of magnetic citric acid bentonite on hexavalent chromium, published in the important journal .

In order to improve the adsorption performance of bentonite on Cr(VI) and improve its solid-liquid separation and recovery capacity, a chitosan-modified composite magnetic adsorption material —— magnetic citrate bentonite (Magnetic Citric Acid Bentonite, MCAB) was constructed. SEM, XRD, VSM, FT-IR were used to characterize and compare the materials before and after modification. The results showed that functional groups such as ‒NH2, ‒OH and magnetic Fe3O4 particles in chitosan were loaded onto citric acid bentonite ( Citric Acid Bentonite, CAB). The adsorption performance of MCAB on Cr(VI) shows that compared with CAB, the adsorption performance of MCAB after compounding is obviously improved, and it has good magnetic separation ability; the pH value has a great influence on the adsorption of Cr(VI), the optimum pH. The value is in the range of 2.0 to 3.0; when the adsorbent dosage is 1.6 g · L‒1, pH value is 3.0, and the initial concentration of Cr(VI) is 10 mg · L‒1, the removal rate of Cr(VI) by MCAB Up to 99%; the fitting results of the adsorption isotherm equation and the kinetic equation are in accordance with the Langmuir adsorption isotherm model and the quasi-secondary kinetic model, respectively. Since the modified ‒NH2 on MCAB is protonated under acidic conditions, it will enhance the electrostatic attraction of Cr(VI). Therefore, the adsorption removal rate of Cr(VI) by MCAB is obviously improved. At the same time, the magnetic field is given to CAB. Fast solid-liquid separation ability. Studies have shown that MCAB has a good effect on the removal of Cr(VI) in simulated wastewater and is expected to be applied to the removal of Cr(VI) in actual wastewater.

Take 2.0 g of CAB in 100 mL of deionized water, ultrasonically disperse for 5 min, then slowly add 1.47 g of FeCl3.6H2O and 0.685 g of FeCl2.4H2O, and continue sonication for 10 min. Pour the mixed suspension after sonication into a three-necked flask. After heating to 60 ° C in the microwave, quickly add 10 mL of 25% (wt) ammonia water, stir at constant temperature for 30 min, then add 20 mL of chitosan solution (0.1 g dissolved in 20 mL 1% (wt) glacial acetic acid), and 2 mL of 5% (wt) glutaraldehyde was added dropwise and stirring was continued for 30 min. After the reaction, the magnetic composite was separated by solid-liquid under the action of an external magnetic field, and washed with absolute ethanol and deionized water several times, vacuum dried at 60 ° C for 12 h, ground and passed through a 200 mesh sieve to prepare a MCAB sample.