竞争干扰对轮叶黑藻吸附Pb(Ⅱ)的影响

Effect of Competitive Interference on the Biosorption of Lead (Ⅱ) by Hydrilla verticallata

沉水植物处理低浓度重金属废水是一项清洁和廉价的技术.主要研究了不同初始浓度和pH条件下,轮叶黑藻鲜样在单一、二元和三元金属离子体系中对铅离子的生物吸附特征.在单一金属离子体系中,不同pH值条件下的实验结果表明,pH值在2.0～6.0间变化时,轮叶黑藻对铅的吸附能力随pH值升高而增强,当初始铅浓度为250 mg/L和pH为5.0时,铅吸附量可达44.65 mg/g.在二元和三元金属离子体系中,铜和锌离子的存在负向干扰轮叶黑藻对铅离子的吸附.在铅和铜二元金属离子体系中,当溶液中铅和铜的初始浓度分别为250 mg/L时,铅吸附量降低为单一金属离子体系中铅吸附量的49.29%.轮叶黑藻对铅离子的吸附符合Langmuir竞争吸附模型(R2=0.966),理论最大吸附量(58.02 mg/g)与实测值相符,且模型计算值与实测值平均偏差仅为15.6%.轮叶黑藻对铅和铜离子的优先吸附实验结果表明,轮叶黑藻对铅、铜2种重金属离子没有优先吸附性能.

Using submerged aquatic plant is a cheap and clean technique to remediate heavy metals in wastewaters.Batch experiments were conducted to assess the biosorption characteristics of Pb(Ⅱ) ions by fresh tissues of Hydrilla verticallata.The biosorption of Pb(Ⅱ) was examined for single,binary and ternary solutions at different initial concentrations and different pH values.The experimental results showed that the biosorption capacity increased with increasing pH from 2.0 to 6.0.The biosortption value reached 44.65 mg /g when initial lead concentration was 250 mg /L and pH = 5.Both Cu(Ⅱ) and Zn(Ⅱ) ions were found to have an adverse effect on the biosorption of Pb(Ⅱ) for binary and ternary solutions.In Pb-Cu binary metal solution,when both initial concentrations of lead and copper ions were 250 mg /L,the biosorption capacity for lead ions was decreased to 49.29% of that in single lead ion solution.The biosorption equilibrium data for the Pb-Cu binary metal solution fitted the Langmuir competitive model well(R2 = 0.966).The theoretical qmax value(58.02 mg /g) was in excellent consistent with that obtained experimentally,and the average relative error between calculated qe and experimental qe values was only 15.6%.Comparison between biosorption of Pb(Ⅱ) and Cu(Ⅱ) by H.verticallata in the binary solution could lead to the conclusion that H.verticallata has no preference of Pb(Ⅱ) over Cu(Ⅱ).