铁锰复合材料吸附工业废水中 铊的机理研究

Mechanism Study of Iron-Manganese Composites for Thallium Removal in Industrial Wastewate

摘要:

铊(Thallium，Tl)是一种高毒性金属，其致死剂量仅为10—15 mg?kg^-1。由于锰氧化物具有优良的吸附性，因此在铊污染防治中展现出很好的应用前景。然而，锰氧化物在吸附铊的过程中会溶出锰，因而对环境造成二次污染。为解决该问题，引入铁元素制备铁锰复合材料，降低吸附过程中锰的溶出。结果表明：铁元素的引入能大幅地减少吸附过程中锰的溶出，当初始Tl₀浓度为 10 mg?L^-1时，1 mg?L^-1的铁锰复合材料对铊的去除率超过99%，同时锰的溶出浓度控制在国家排放标准以内（0.3 mg?L^-1），达到了0.11 mg?L^-1；等温吸附曲线表明，当吸附温度为308 K时，铁锰复合材料的吸附符合Freundlich吸附曲线（R²=0.94），吸附最大容量为539.4 mg·g^-1。说明，铁锰复合材料在有效降低锰溶出的同时，也能够高效地去除铊。

Abstract:

Metal thallium （Tl） is extremely poisonous. The fatal dose of thallium for humans is about 10—15 mg?kg^-1. Manganese oxides are promising for the prevention and control of thallium pollution because of their excellent adsorption properties. Nevertheless， manganese leaching from manganese oxides during thallium adsorption can result in secondary environmental pollution. Therefore， Fe-Mn composites were prepared by introducing Fe to reduce the leaching of Mn during adsorption. The outcomes demonstrate that adding Fe can greatly lessen manganese leaching. When the initial Tl concentration was 10 mg·L^-1， the removal rate of thallium by Tl 1 mg·L^-1 Fe-Mn composite material was more than 99%， and the concentration of Tl in the treated aqueous solution was only 0.14 mg·L^-1. Besides， the concentration of Mn leaching was also regulated within the national emission standard （0.3 mg·L^-1） and reached 0.11 mg·L^-1. The isothermal adsorption curve showed that the maximum adsorption capacity of the Fe-Mn composite was 539.4 mg·L^-1 at 308 K. This indicated that the Fe-Mn composite could effectively reduce the Mn leaching and remove Tl efficiently at the same time.