以黄麻纤维为吸附剂,对水溶液中痕量Cd^2+离子的吸附性能进行了研究。采用扫描电镜对黄麻纤维的微观结构进行了观察,单根纤维的直径约50~100μm,纤维内部有很多直径约为数μm的孔道。考察了水溶液的初始p H值、吸附剂与Cd^2+离子溶液的接触时间对吸附效率的影响。结果表明,接触时间120 min、溶液的初始p H值为7~8,黄麻纤维对Cd^2+离子具有最佳的吸附效率。采用Langmuir和Freundlich等温吸附模型对黄麻纤维等温平衡吸附Cd^2+离子的实验数据进行了拟合,发现Langmuir模型很好地描述了黄麻纤维对Cd^2+离子的吸附行为(R^2≥0.993),吸附属于单分子层吸附,平衡吸附量为4.62 mg/g。吸附Cd^2+离子前后的FTIR分析表明,羧基是黄麻纤维吸附Cd^2+离子的主要作用位点,在实验条件下,仍然存在没有被Cd^2+离子配位的自由羧基。
The absorption performance of aqueous trace Cd^2+ions using jute as a sorbent was studied. The microstructure of jute fibers was observed by SEM technique,the observation indicated that the diameter of a single fiber is about 50 ~ 100 μm and there are lots of pores with diameter of several micron. The effect of the initial p H and contact time on the removal rate of Cd^2+ions were investigated,it found that the optimized conditions are 7 ~ 8 of p H and 120 min of contact time. The experimental data of isothermal equilibrium adsorption were fitted by using Langmuir and Freundlich equations respectively. The results shows Langmuir isotherm can describe the behaviors of jute absorbing Cd^2+ions,indicating the absorption can be attributed to mono-molecule layer adsorption. The maximum sorption capacity of sorbent is 4. 62 mg / g. The FTIR spectra of jutes before and after absorbed represent the carboxyl groups in the jute is the main sites of Cd^2+ions acting with the fibers and free carboxyl groups which have not coordinated with Cd^2+ions still exist in the fibers.