穗花狐尾藻铅吸附特征与机理

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100mg/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250mg/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(q_max)可达52.12mg/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(R_Ca2+=0.943,P<0.01；R_Mg2+=0.915,P<0.01). Pb2+更易与Ca2+和Mg2+产生离子交换而被吸附. 

Characteristics and Mechanisms of Lead Biosorption on Myriophyllum Spicatum

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 100mg/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 250mg/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, q_max, indicated that the maximum biosorptive capacity of Pb2+ on M. spicatum could reach to 52.12mg/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+ (R_Ca2+=0.943, P<0.01; R_Mg2+=0.915, P <0.01). Pb2+ can more easily exchanged with divalent elements such as Ca2+ and Mg2+ for their biosorption.