Study on adsorption of chromium(Cr3+)by endophytic bacteria Bacillus cereus J01 isolatedfrom Leersia hexandra Swartz

The effects of pH, temperature, initial Cr3+ concentration, adsorbent dosage, time, and other factors on the adsorption capacity of Cr3+ were examined by the single factor test method using inactivated Bacillus cereus J01 strain as biological adsorbent in order to investigate the adsorption performance of Cr3+ by endophytic bacterium Bacillus cereus J01 from Leersia hexandra Swartz. The kinetic, thermodynamic, and isothermal adsorption processes were analyzed. Infrared spectroscopy was used to provide a preliminary analysis of the Cr3+ adsorption mechanism. The results were as follows:(1)In the reaction system of 50 mL, inactivated Bacillus cereus J01 reached the best adsorption performance on Cr3+ when pH value was 6, temperature was 40 ℃, initial concentration of Cr3+ was 150 mg·L-1, adsorbent dosage was 0.2 g and adsorption time was 12 h. The equilibrium adsorption capacity was 34.30 mg·g-1 and the removal rate of Cr3+ was 91.60%.(2)The Langmuir isothermal adsorption model could better simulate the adsorption of Cr3+ by inactivated Bacillus cereus J01. The adsorption process was more similar to monolayer adsorption.(3)The adsorption kinetics analysis showed that the adsorption of inactivated Bacillus cereus J01 on Cr3+ was more consistent with quasi-second-order kinetic rate equation.(4)Thermodynamic analysis of adsorption showed that at 40 ℃, △G, △H and △S were -2.609 kJ·mol-1, 61.792 kJ·mol-1 and 206.11 J·mol-1, respectively. The adsorption process was spontaneous at 40 ℃.(5)The results of infrared spectroscopy showed that the adsorption of inactivated Bacillus cereus J01 on Cr3+ could be attributed to the effects of amino, hydroxyl and carbonyl groups in the cell components. The results show that the inactivated bacteria of this bacterium has strong adsorption capacity for Cr3+, and has good application potential in the treatment of environmental chromium pollution.