Cu 2 + adsorption and retardation effect of compound adsorbent by adding bacterium powder and amphoteric modified clay in active calcium silicate

modified clay in active calcium silicate LI Wen-bin1*, DENG Hong-yan1, LI Xue-lian1, LIU Wei2, LEI Gang-gang1, MENG Zhao-fu2,3, LUO Chuan1, WANG Teng2 (1.College of Environmental Science and Engineering, China West Normal University, Nanchong 637009, China; 2.Department of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China; 3.Key Laboratory of Plant Nutrition and Agri-Environment in Northwest China, Ministry of Agriculture, Yangling 712100, China) Abstract:To study the adsorption characteristics and retardation effects of Cu2+ under different compound adsorbents mixed by bacterium powder, BS(BS-12, dodecyl dimethyl betaine)modified clay and active calcium silicate, Saccharomyces cerevisiae and BS-modified ben原 tonite(Bentonite modified by modified ratio of 100% CEC of Bentonite)were mixed in active calcium silicate(CK), with a mass ratio of 10%, 20%, and 50% as the compound adsorbents(J-Ca and BS-Ca), and batch method was used to analyze the Cu2 + adsorption isotherms of the samples under different environmental conditions, such as under different pH and temperature values, also the Cu2+ retarda原 tion effects of the compound adsorbents were identified. The Cu2+ adsorption capacity of the J-Ca gradually decreased as the proportion of bacterium powder increased, whereas the adsorption of Cu2+ by the BS-Ca increased as the proportion of BS clay increased. The adsorption of Cu2+ by the J-Ca and BS-Ca in the same proportion of bacterium powder and BS clay decreased as follows:BS-Ca>CK>J-Ca. The ad原 sorption of Cu2+ by the adsorbents was a spontaneous process that increased both enthalpy(except 50%BS-Ca)and entropy. Temperature had no significant effect on the Cu2+ adsorption of either the CK or the 10%J-Ca at 10~30 益 but did significantly affect the 25%J-Ca and 50%J-Ca. As the proportion of BS clay increased to 50%, the effect of temperature on the adsorption of Cu2+ by the BS-Ca changed from