给水厂污泥对Hg(Ⅱ)的吸附性能

Hg(Ⅱ)ADSORPTION PERFORMANCE BY WATER TREATMENT RESIDUAL

给水厂污泥具有较强的吸附能力,可作为从水溶液中去除重金属的潜在吸附剂。通过试验分析了给水厂污泥(WTR)作为吸附剂去除溶液中Hg(Ⅱ)时,pH值、Hg(Ⅱ)初始浓度、污泥粒径以及温度对Hg(Ⅱ)吸附性能的影响,确定了吸附过程的动力学及吸附等温模型,并探究了其吸附机理。结果表明:溶液pH值对给水厂污泥吸附Hg(Ⅱ)具有较大影响,当pH=8.0时吸附效果最佳。采用粒径较小的污泥有利于对Hg(Ⅱ)的吸附,污泥对Hg(Ⅱ)的吸附量随着初始浓度的增加而增加。给水厂污泥对Hg(Ⅱ)的吸附符合准二级动力学模型,平衡等温线符合Langmuir吸附等温模型,25℃条件下pH为7.0时污泥的饱和吸附量达到69.13 mg/g。升温有利于给水厂污泥对Hg(Ⅱ)的吸附。通过分析吸附前后污泥比表面积和微孔体积的变化发现,颗粒内扩散是给水厂污泥吸附Hg(Ⅱ)的限速步骤。

Water treatment residual(WTR)can be used as a potential adsorbent to remove heavy metal ions from aqueous solution.The effects of pH value,initial concentration of Hg(Ⅱ),sludge size and temperature on the adsorption performance of WTR as the adsorbent were studied.The kinetics of the adsorption process and adsorption isotherm model were determined,and then its adsorption mechanism was explored.The results showed that the pH of the solution had a great influence on the adsorption of Hg(Ⅱ)by WTR and the adsorption capacity was largest at pH=8.0.A smaller particle size was conductive to the adsorption of Hg(Ⅱ),and the adsorption capacity increased with the increase of initial Hg(Ⅱ)concentration.The adsorption of Hg(Ⅱ)by WTR complied with the pseudo-second-order kinetic model,and the equilibrium isotherm complied with the Langmuir isotherm model,the maximum adsorption capacity was 69.13 mg/g at a temperature of 25℃and pH of 7.0.A higher temperature was conducive to the adsorption of Hg(Ⅱ).It was found that intraparticle diffusion was the rate-limiting step of Hg(Ⅱ)adsorption,by analyzing the changes in the specific surface area and pore size distribution of the WTR before and after adsorption.