原子吸收光谱法研究巯基改性膨润土对Pb2+的吸附解吸

通过红外光谱(FTIR)法和扫描电镜(SEM)对钙基和巯基改性膨润土的官能团和表面结构进行了比较分析，以火焰原子吸收光谱法(FAAS)为检测手段，研究了巯基改性膨润土对Pb2+吸附的影响因素并优化了吸附条件，讨论了模拟酸雨解吸Pb2+的条件。比较了钙基和巯基改性膨润土作为吸附剂对水溶液中Pb2+的吸附、固定能力。研究表明：25 ℃下，吸附时间为60 min、离子强度为0.1 mol·L-1的KNO₃、pH 6.0时，5.0 g·L-1巯基改性膨润土对100 mg·L-1的Pb2+的吸附率达到98%以上，平衡吸附量达到67.27 mg·g-1，吸附能力明显优于钙基膨润土(9.667 mg·g-1)，吸附过程符合Langmuir和Freundlich等温线方程。用pH 3.50的极限酸度模拟酸雨进行解吸，解吸率为0。表明该巯基改性膨润土对Pb2+具有很强的吸附、固定能力，适于重金属铅污染土壤中铅的吸附固定修复之用。

Study of Adsorption and Desorption of Behaviors of Pb2+ on Thiol-Modified Bentonite by Flame Atomic Absorption Spectrometry

A comparative analysis of the functional groups and surface structure of the Ca-bentonite (RB) and thiol-modified bentonite (TMB) were characterized by means of FTIR and SEM. The absorptive property of Pb2+ on TMB and RB and its influential factors was studied and the conditions for the adsorption were optimized by using FAAS method. Then the conditions for desorption of Pb2+ from the TMB by using simulated acid rain were studied and the contrast analysis of absorptive stability of Pb2+ on TMB and RB was given. The results showed that the adsorption rate of Pb2+ by TMB could reach more than 98%, when the initial Pb2+ concentration was 100 mg·L-1, the liquid-solid ratio was 5 g·L-1, pH was 6.0, KNO₃ ionic strength was 0.1 mol·L-1 and adsorption period was 60min at 25 ℃. The saturated adsorption capacity of TMB was 67.27 mg·g-1; it’s much more than that of RB (9.667 mg·g-1). The adsorption of Pb2+ on TMB follows Langmuir and Freundlich isotherm models well. Desorption experiments of Pb2+ from TMB with simulated acid rain (pH 3.50) were done, and the desorption rate was 0. The results showed that TMB has a strong adsorption and fixation capacity for Pb2+; it is adapted to lead contaminated soil for chemical remediation.