穗花狐尾藻铅吸附特征与机理

摘要

为探讨沉水植物对低浓度重金属废水的吸附特征,研究了不同重金属质量浓度及pH影响下,穗花狐尾藻鲜样在单一、二元和三元金属离子体系中对pb2+的生物吸附特征及吸附机理.结果表明,在单一pb2+体系中,穗花狐尾藻对pb2+的吸附能力随pH的升高而增强；当初始ρ(Pb2+)为100 mg/L、初始pH为6.5时,pb2+吸附率可达80.95％.Cu2+和Zn2+的存在负向干扰穗花狐尾藻对Pb2+的吸附；当初始ρ(Cu2+)和ρ(Pb2+)均为250 mg/L时,Cu2+干扰下pb2+吸附量降低为单一体系中pb2+吸附量的62.40％.Sips和Langmuir模型的拟合效果优于Freundlich模型.根据Langmuir模型模拟,穗花狐尾藻对pb2+的理论最大吸附量(qmax)可达52.12 mg/g.红外光谱分析表明,-OH、-C=O、-COOH、C-O及C-H为主要作用基团.吸附pb2+后,溶液中矿质元素含量增加,ρ(Ca2+)和ρ(Mg2+)与初始ρ(Pb2+)达到极显著正相关(Rca2+=0.943,P＜0.01;RMg2+=0.915,P＜0.01).Pb2+更易与Ca2+和Mg2+产生离子交换而被吸附.%In order to examine the biosorptive characteristics of submerged aquatic plants on heavy metals with low concentration,batch experiments were conducted to assess the biosorptive characteristics of Pb2+ in fresh tissues of Myriophyllum spicatum for single,binary and ternary solutions at different initial concentrations and pH values.The mechanism for Pb2+ biosorption was further discussed.For single Pb2+ solution,the experimental results showed that the biosorptive capacity for M.spicatum increased with increasing pH.The biosorptive efficiency reached to 80.95％ when initial concentration of Pb2+ was 100 mg/L under the condition of pH 6.5.Both Cu2+ and Zn2+ for M.spicatum had adverse effects of Pb2+ biosorption.When initial concentrations of Pb2+ and Cu2+ were 250 mg/L,the biosorptive capacity for Pb2+ decreased to 62.40％ of that in single Pb2 + solution.Sips and Langmuir models were used to simulate on Pb2+ biosorption onto M.spicatum better than using Freundlich model.The Langmuir isotherm parameter,qmax,indicated that the maximum biosorptive capacity of Pb2+ on M.spicatum could reach to 52.12 mg/g.The FTIR spectra of M.spicatum showed that the possible functional groups responsible for Pb2 + binding were-OH,-C =O,-COOH,C-O and C-H.The concentrations of mineral elements in solution increased after Pb2+ biosorption,and there were extreme significant positive correlations between the concentrations of Ca2+,Mg2+ and that of Pb2+ (Rca2 + =0.943,P ＜ 0.01 ; RMg2 + =0.915,P ＜ 0.01).Pb2+ can more easily exchanged with divalentelements such as Ca2+ and Mg2+ for their biosorption.