[ Objective ] Batch experiments were conducted to assess the competitive effects of Cu2+ and Cd2+ on the biosorplion of Pb2+ ions by fresh activated sludge. [ Method] The biosorption capacity of Pb2+ was studied for single,binary and ternary solutions at different initial concentrations and pH values. [ Result ] The biosorplion capacity was significantly affected by contact time, pH value and initial ion concentration. The single heavy metal biosorplion experiments data was fitted to two isotherm models of Langmuir and Freundlich, respectively, the Langmuir isotherm model gave better fit for the experimental data. The maximum Pb2+ biosorption capacity was 186.81 mg/g in the single metal biosorption conditions, while the data decreased to 138.94 mg/g by adding 30 mg/L Cu2+ and raised to 214.58 mg/g by adding 30 mg/L Cd2+.In the preference experiment study,the initial adsorption mole numbers of Pb2+ and Cu2+ were nearly the same,but desorption of Cu2+ (0.300 mmol/L) seemed to be more easier than Pb2+ (0.089 mmol/L) after adding the second heavy metal. [Conclusion] Low concentration of Cd2+ in the binary system may promote the biosorption of Pb2+ by activated sludge,but have adverse effects at higher concentration. In spite of low or high concentration, Cu2 + restrains the biosorption of Pb2+ with more obvious effects. Comparison between biosorption of Pb2+ and Cu2+ by fresh activated sludge in the binary solution could lead to the conclusion that the biosorbent has better preference of Pb2+ to Cu2+.%[目的]通过批量吸附试验,研究Cu2+和Cd2+对活性污泥吸附Pb2+的竞争吸附影响效果.[方法]在单金属、双金属和三金属体系中,不同的pH和不同的初始浓度条件下,对比了活性污泥对pb2+的生物吸附性能.[结果]吸附时间、pH和初始重金属离子浓度对活性污泥吸附Pb2+具有显著影响.分别采用Langmuir和Freundlich吸附模型,拟合了单金属Pb2+的吸附曲线,其中,Langmuir吸附模型可较好地表征污泥对Pb2+的吸附特性.在单一金属吸附情况下,活性污泥对Pb2+的最大比吸附量(Q,)为186.81 mg/g.在双金属吸附体系中,当添加30 mg/L Cu2+时,Qt减少为138.94 mg/g,相反,当添加30 mg/L Cd2+时,Qt上升为214.58 mg/g.在偏好吸附试验中,在初始吸附量基本相同的情况下,加入第二种金属后,Pb2+的解吸附量为0.089 mmol/L,而Cu2+的解吸附量为0.300 mmol/L.[结论]在多金属吸附体系中,低浓度Cd2+对污泥吸附Pb2+有促进作用,但高浓度会抑制吸附过程;Cu2+不论低浓度还是高浓度,都对污泥吸附Pb2+有抑制作用,且抑制作用大于Cd2+.相对于Cu2+,活性污泥对Pb2+有更好和更稳定的吸附能力.
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