铬是一种重金属痕量元素,人体通过食物链摄入过量的铬会在人体内富集,随之产生中毒反应。研究Cr(Ⅲ)的浓度、反应时间、反应温度、pH值等因素对Cr(Ⅲ)在黄土上吸附特性的影响,结果表明黄土对Cr(Ⅲ)的吸附非常迅速,并且吸附量非常大,等温吸附模型Freundlich和Dubinin-Radushkevich(D-R)模型都能很好地解释Cr(Ⅲ)在黄土上的吸附过程。热动力学分析表明,吸附是一个自发的过程,升温可促进吸附作用的进行。随着温度的不断升高,Cr(Ⅲ)的吸附量逐渐增大。溶液的pH值是影响Cr(Ⅲ)吸附效果的一个重要因素,当pH〉6时,Cr(Ⅲ)几乎完全被去除。利用X光衍射图谱和红外光谱分析,探讨黄土与Cr(Ⅲ)的结合机制,黄土中的高岭土、石英等黏土矿物以及有机质成分对吸附过程起重要作用。
Chromium is a trace element and toxic effect will be caused by excessive intake of chromium. Factors including the concentration of Cr(Ⅲ), reaction time, reaction temperature and pH value were studied to investigate the adsorption behavior of loess soil towards Cr(Ⅲ). The researches indicated the adsorption speed is very fast; the adsorption capacity of Cr(Ⅲ) on loess soil is very big; and the adsorption test results can be well interpreted by three isotherm models, i.e. Freundlich and Dubinin-Radushkevich (D-R) models. The thermodynamic analysis indicates that the adsorption process of Cr(III) on loess soil is spontaneous, and higher temperature is benefit to the adsorption process. Higher temperature leads to higher adsorption capacity; higher initial concentration of Cr(Ⅲ) leads to higher adsorption capacity too; pH value has great influence on the removal efficiency of Cr(Ⅲ) from aqueous solution, and Cr(Ⅲ) can be nearly completely removed at pH〉6. X-ray diffraction spectra and Fourier transform-infrared spectra were used to fiarther discuss the adsorption mechanism of Cr(III) on loess soil; and the analysis indicates that the clay minerals such as kaolin and quartz and organic matter in loess play important roles in Cr(Ⅲ) removal.