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表生环境中,吸附是硒进入固相沉积环境的重要途径之一。为了厘清硒氧阴离子团吸附行为及其影响因素,本文选择赤铁矿、二氧化锰和氧化铝作为吸附剂,采用批次实验的方法,研究了溶液pH、硒浓度以及反应时间等对硒的吸附影响。结果表明:为了达到较理想的吸附效果,溶液的pH应控制在4~6之间,在室温、pH为5时,赤铁矿、二氧化锰和氧化铝对亚硒酸盐的饱和吸附量分别约为1.62×10-3、0.33×10-3和1.07×10-3,对硒酸盐的饱和吸附量分别约为1.0×10-3、0、0.55×10-3;其吸附规律均符合Langmuir等温吸附方程,且理论最大吸附量与实验得出的最大吸附量基本一致。运用准一级动力学、准二级动力学、Elvoich方程和颗粒内扩散模型4种动力学模型对实验数据进行拟合,发现硒吸附过程运用准二级动力学方程表示时相关性最好,表明了硒氧阴离子团在铁、锰、铝氧化物表面的吸附过程较为复杂,可能涉及表面物理吸附和颗粒扩散等过程。
In superficial environment, adsorption is one of the important ways for selenium to enter into the solid depositional environment. In order to clarify the adsorption behavior of selenoanion groups and its influencing factors, hematite, manganese dioxide and alumina were chosen as adsorbents in this paper. The effects of solution pH, selenium concentration and reaction time on selenium Adsorption effects. The results show that in order to achieve a better adsorption effect, the pH of the solution should be controlled between 4 and 6. At room temperature and at pH 5, the saturated adsorption capacity of hematite, manganese dioxide and alumina to selenite Respectively about 1.62 × 10-3, 0.33 × 10-3 and 1.07 × 10-3, the saturated adsorption capacity of selenate is about 1.0 × 10-3,0,0.55 × 10-3, respectively. The adsorption laws According to Langmuir isothermal adsorption equation, and the theoretical maximum adsorption amount and experimentally obtained maximum adsorption amount is basically the same. Quasi-first-order kinetics, quasi-second-order kinetics, Elvoich equation and intra-particle diffusion model were used to fit the experimental data. It was found that the quasi-second-order kinetic equation of selenium adsorption process showed the best correlation, The results show that the adsorption process of selenoanion groups on the surface of iron, manganese and aluminum oxide is more complicated, which may involve the processes of surface physical adsorption and particle diffusion.