针铁矿对Pb~(2+)的吸附特征及影响因素研究

通过恒温振荡平衡法研究了Pb~(2+)在针铁矿上的等温吸附和吸附动力学特征,探讨了吸附的影响因素.结果表明:(1)随Pb~(2+)平衡浓度和pH的增大,针铁矿对Pb~(2+)的吸附量逐渐增大.(2)针铁矿对Pb~(2+)的等温吸附可用Freundlich和Langmuir方程较好地拟合.(3)在相同温度和pH下,随离子强度的提高,针铁矿对Pb~(2+)的吸附量增大.(4)在相同离子强度和pH下,针铁矿对Pb~(2+)的吸附量总体随温度升高而增大.针铁矿对Pb~(2+)的吸附是自发进行的吸热反应.(5)针铁矿吸附Pb~(2+)的过程可分为初始的快吸附和随后的慢吸附2个阶段.pH影响吸附反应快慢,随pH增大吸附速率增大;随着pH的增大,达到平衡吸附的时间缩短.吸附动力学方程用Elovich方程拟合最佳.

Characteristics and influence factors of Pb~(2+) adsorption by goethite

The removal of Pb~(2+) from aqueous solution by adsorption on goethite was investigated by balanced vi-bration method, and the effect of adsorption treatment conditions (initial pH,temperature and ionic strength) on the adsorptive capacity for Pb~(2+) was detected. The adsorption,thermodynamics and kinetics characteristics of Pb~(2+) ad-sorption process was analyzed. The results showed that the adsorptive capacity of goethite for Pb~(2+) increased with the increasing initial pH value of solution. The process of Pb~(2+) adsorption on goethite could be well fitted by Freundlich and Langmuir equation. Increase the ionic strength of the solution was beneficial for adsorption capacity. The higher maximum adsorption capacities were found at higher temperature, because it was the spontaneous and endothermic adsorption process. The process of Pb~(2+) adsorption process could divided in two phases of rapid adsorption and slow adsorption, increasing pH value of reaction media could accelerate goethite absorption for more lead Pb~(2+). Evolich e-quation was best to express the adsorption kinetics of Pb~(2+) on goethite.