pH对δ-MnO2和水铁矿吸附As(Ⅴ)的影响

摘要

研究了初始pH对δ-MnO2和水铁矿吸附As(Ⅴ)的动力学和热力学过程的影响.结果表明,不同初始pH对水铁矿去除As(Ⅴ)的效果影响不明显,而对δ-MnO2去除As(Ⅴ)的效果影响较大.在相同的吸附时间下,初始pH=5.0时,As(Ⅴ)去除率最高,且随初始pH增大而降低.当初始pH=5.o时,δ-MnO2和水铁矿对As(Ⅴ)的平衡吸附量总体上都大于初始pH=7.0或初始pH=9.0时.准二级动力学方程可以很好地描述δ-MnO2和水铁矿吸附As(Ⅴ)的动力学过程.Freundlich方程拟合水铁矿和δ-MnO2吸附As(Ⅴ)的过程优于Langmuir方程.%Effects of initial pH on As(Ⅴ) adsorption kinetics and isotherm curve by δ-MnO2 and ferrihydrite were conducted.Results indicated that initial pH had little effect on As(Ⅴ) removal by ferrihydrite,but relatively great effect by δ-MnO2.As(Ⅴ) removal efficiency was highest when initial pH=5.0 at the same adsorption time.Besides,As(Ⅴ) removal efficiency dropped down as initial pH increased.Equilibrium adsorption quantity was higher when initial pH=5.0 than when initial pH=7.0 or 9.0.The adsorption kinetic process on As(Ⅴ) by δ-MnO2 or ferrihydrite could well be described by the pseudo-second-order equation.The adsorption isotherm curve was better fitted for Freundlich equation than Langmuir equation.