膨化稻壳对铀及伴生重金属离子的吸附机理

Adsorption characteristics and mechanism of U(Ⅵ) and associated heavy metals on expanded rice husk

对粮食生产中的大量废弃的米稻壳经膨化技术加以改性,通过研究新型吸附对于放射性废水中的核素U6+及伴生重金属Pb^(2+)的吸附特性,考察p H、吸附剂用量、温度、时间和初始浓度等影响吸附的因素,揭示新型吸附剂在吸附过程中的各种离子在溶液中的反应动力学、热力学参数以及等温吸附规律。通过实验证明稻壳经膨化改性后对核素U^(6+)及伴生重金属Pb^(2+)吸附效果明显,当p H分别为3、5时,吸附时间为40min时,溶液中U^(6+)和Pb^(2+)的去除率分别可达到89.10%、96.58%;通过吸附理论拟合研究证明新型吸附剂对U^(6+)和Pb^(2+)的吸附行为符合Langmuir等温单分子层吸附模型理论。

This article aims to apply the expanded rice husk（ERH）,which is derived from the natural agricultural waste in grain production in South China,to the treatment of nuclide and associated heavy metals. Since the p H,sorbent dosage,adsorption temperature,adsorption time and initial concentration have significant effects on the removal of U（Ⅵ） and Pb（Ⅱ） in radioactive waste water,the adsorption characteristic of the target ions on this novel sorbent were investigated. The reaction kinetics,thermodynamics,as well as the adsorption isotherm of the adsorption process on the sorbent were also studied. Adsorption experiments of U（Ⅵ） and Pb（Ⅱ） to the rice husk which was modified by expanding were performed. Results showed that the sorbent had good adsorption capabilities to those ions,especially to Pb（Ⅱ）. When the p H was 3 and 5,the adsorption time was 40 minutes,the removal efficiencies of U（Ⅵ） and Pb（Ⅱ） in the simulated solution could reach 89.10% and 96.58%,respectively. According to the adsorption theory,the adsorption behavior of U（Ⅵ） and Pb（Ⅱ） accorded with the Langmuir single-molecular layer adsorption model theory.