利用Fe^0和Fe^(2+)在皂素废水中生成绿锈去除硫酸根

Using Fe^0 and Fe^(2+) to generate green rusts to remove sulfate in saponin wastewater

皂素废水中高浓度的SO_4^(2-)对环境危害大,厌氧环境下同时投加Fe^0和Fe^(2+)生成硫酸盐绿锈增强SO_4^(2-)的去除,实验研究了各因素对去除SO_4^(2-)的影响。结果表明,降低初始p H能快速提升SO_4^(2-)的去除率,25~35℃范围内提高温度有利于SO_4^(2-)的去除,Fe^(2+)浓度对去除效果影响显著,随着Fe^(2+)浓度的增加,SO_4^(2-)去除率快速上升。初始pH为2、温度为25℃的条件下,10 g·L^(-1)的Fe^0和1 000 mg·L^(-1)的Fe^(2+)能去除93.1%初始浓度为1 000 mg·L^(-1)的SO_4^(2-)。XRD和SEM表征结果显示,去除过程中铁粉表面有疏松多孔结构的Fe_3O_4生成,有利于SO_4^(2-)与Fe^0接触反应,促进硫酸盐绿锈的生成,进一步增强SO_4^(2-)的去除。动力学分析显示,去除过程拟合伪二级动力学模型,吸附SO_4^(2-)的过程以单分子层吸附为主。

High concentrations of SO4^2- in saponin wastewater are very harmful to the environment.Under the anaerobic condition,simultaneous addition of Fe^0 and Fe^2＋enhanced the removal of SO4^2- by generating sulfate green rust.The effects of various factors on the removal of SO4^2- were studied.The results showed that reducing the initial p H quickly improved the removal of SO4^2-.In the range of 25 to 35 ℃,higher temperatures favored the removal of SO4^2-.Fe^2＋concentration had a significant effect on the removal effect.With the increase of Fe^2＋concentration,the removal rate of SO4^2- increased rapidly.When the initial pH was 2,the temperature was 25 ℃and the initial concentration of SO4^2- was 1 000 mg·L^-1,Fe^0 of 10 g·L^-1 and Fe^2＋of 1 000 mg·L^-1 removed SO4^2- of 93.1%.XRD and SEM results showed that Fe3O4 with loose porous structure was formed on the surface of iron powder during the removal process of SO4^2-.It was propitious to the contact reaction of SO4^2- and Fe^0,which promoted the formation of sulfate green rust.Thereby,the removal of SO4^2- was furtherly enhanced.The kinetic analysis showed that the removal of SO4^2- was fit to the pseudo second order kinetics model,and the adsorption of SO4^2- was dominated by monolayer adsorption.