DAI Qunwei, WANG Yan, ZHAO Yulian, ZHOU Shiping, YANG Xingwang, ZHANG Wei
In order to explore the adsorption characteristics, liquid pH, and electrical conductivity variation characteristics of bupleurum dreg to the waste water containing zinc, the bupleurum dreg was utilized as biosorbent to remove Zn2+ with batch experiments. The effect factors on biosorption were analyzed, which included pH values, initial Zn2+ concentration (C0), biosorbent concentration (ρm), and mesh size (Mz). Meanwhile, the isotherm biosorption and kinetics was analyzed. The results showed that the optimum condition for biosorption was as follows: pH was 4.5~6.0, ρm was 4.0~8.0 g/L, C0 was 0.1~2.0mmol/L, Mz was 40~100 mesh. The isotherm adsorption curve of Zn2+ on bupleurum dreg accorded well with Langmuir and Freunlich model, and the R2 value was 0.978 and 0.989 while the value of qmax was 19.96 mg/g. This shows that a bupleurum dreg has excellent adsorption capacity to zinc ions. The kinetics analysis showed that the biosorption of Zn2+ on bupleurum dreg was a rapid process, and the R2 values were all above 0.997. These indicated that its limit step was chemical adsorption process. The variation trend of pH values in liquid was increasing rapidly at initial adsorption phase and then changed slowly in the succedent phases.
