干旱半干旱地区湖泊沉积物对Cu^(2+)的吸附-解吸研究

Study on Adsorption-desorption Behaviors of Cu^(2+) by Lake Sediments in Arid and Semi-arid Region

吸附-解吸是重金属在沉积物中迁移转化的重要过程。本文研究干旱半干旱地区湖泊———乌梁素海不同区域沉积物对Cu2+的吸附-解吸过程。结果表明,吸附过程中,pH值逐渐降低;沉积物TOC含量越高,其对Cu2+的吸附能力也越强;生活污水和工业废水影响的S1样点及受农田退水影响的S2样点对Cu2+的吸附量相对较低,而相对较洁净的S3和S4样点具有较高的Cu2+吸附量。4个样点吸附量能力大小为S3>S4>S2>S1。解吸实验显示,沉积物吸附的Cu2+大部分都不能被解吸。试验结果符合Langmuir和Freundlich等温吸附方程,Langmuir方程的拟合效果要好于Freundlich方程,Langmuir方程拟合的饱和吸附量分别为3.31 mg/g、4.84 mg/g、8.39 mg/g和7.75 mg/g。

Adsorption-desorption are important processes of heavy metals during their migration and conversion in sediments. This work researched the adsorption-desorption processes of Cu2＋ in different sediment samples collected from Lake Wuliangsuhai where locates in arid and semi-arid region. The result showed that pH value decreased during Cu2＋ adsorption; the higher the TOC content in sediments, the stronger the Cu2＋ adsorption; the Cu2＋ adsorption capacity of sampling site S1 influenced by domestic sewage and industrial wastewater and S2 influenced by the drainage from farmlands were relatively low; at the site S3 and S4 where are rdatively dean showed higher adsorption capacity of Cu2＋. The adsorptive capacity of Cu2 ＋ ranked as S＋ 〉 S4 〉 S2 〉 S1. Desorption experiments showed that most of the Cu2＋adsorbed by the sediment could not be desorbed. The data obtained in this study were fitted using Freundlich and Langmuir isothermal adsorption equations, of which the effect of Langmuir equation showed better than the Freundlich equation. The calculated saturation adsorptions using the Langmuir equation were 3.31, 4.84, 8.39 and 7.75 mg/g for the site S1, S2, S3 and S4 respectively.