pH对穗花狐尾藻吸附重金属镉的影响

运用沉水植物修复水体中低浓度重金属污染，研究不同pH条件下，沉水植物——穗花狐尾藻鲜样对重金属镉的吸附特征. 结果表明，pH对吸附结果影响较大，且在适宜的范围内，等温吸附均可用线性Langmuir模型和拓展Langmuir模型来描述. 当初始pH为3.0～7.0时，Langmuir模型的相关系数(R2)均可达0.954 7(n21)以上，但当初始pH为2.0时，穗花狐尾藻对重金属镉的吸附不符合Langmuir模型.当初始pH为3.0～6.0，初始ρ(镉)(即C₀)为16～72 mg/L时，分别有38%的Langmuir模型计算值，75%的拓展Langmuir模型计算值与实测值偏差小于10%，这表明穗花狐尾藻吸附重金属镉时，拓展Langmuir模型比Langmuir模型有更好的拟合效果. 总体来说，穗花狐尾藻对镉的吸附，最适宜的初始pH为5.0. 

Effect of pH on Cadmium Bio-sorption by Myriophyllum spicatum

Submerged aquatic plant was used to remediate heavy metal water pollution at low concentrations. Bio-sorption of cadmium by fresh tissues of Myriophyllum spicatum, a submerged aquatic plant, was characterized in an artificial solution system at various initial pH. The results indicated that cadmium bio-sorption was strongly pH dependent, and its isotherms were well described by the Langmuir and extended Langmuir sorption models within the appropriate range. At an initial pH of 3.0-7.0, the Langmuir model had good simulations with measured data with a coefficient of R2>0.9547 (n=21), whereas, at an initial pH of 2.0, the isotherms of cadmium bio-sorption by M. spicatum were unable to be simulated using the Langmuir models. With initial pH of 3.0-6.0 and initial cadmium mass concentration (C_0) of 16-72 mg/L, the predicted equilibrium sorption amount with a relative error of <10% against the experimental equilibrium sorption amount were 38% of predicted data for the Langmuir model and 75% of predicted data for the extended Langmuir model. This suggests that the extended Langmuir model has better simulation for cadmium bio-sorption by M. spicatum than the Langmuir model. On the whole, the optimal initial pH in this study was 5.0.