钠型丝光沸石吸附水溶液中铜离子平衡及动力学研究

Adsorption of Copper Ions from Aqueous Solution by Na-mordenite: Equilibrium and Kinetic Studies

研究了沸石吸附水溶液中铜离子时多种因素(时间、吸附温度、初始浓度、pH值、吸附剂量、离子强度等)对吸附过程的影响。实验结果表明,沸石对铜离子的吸附过程能很好地遵循准二级动力学模型,其相关性系数均达到0.999,且吸附速率常数k2随吸附过程的温度升高而增加。其相应的吸附过程的活化能Ea为11.256kJmol/L。Langmuir、Freundlich及Dubinin-Radushkevich(D-R)等方程可较好地拟合热力学数据。吸附过程的热力学参数!G°<0、!H°>0,表明水溶液中铜离子在沸石上的吸附是一个自发的、吸热的过程。D-R等温方程拟合计算结果反映该吸附过程中主要为离子交换过程。沸石对铜离子的单位吸附量随初始浓度的升高而增大;在pH2～6间随pH升高而增加;增大吸附剂投加量有利于提高吸附效率,向溶液中加入一定量的NaNO3则会使沸石对铜离子的吸附能力降低。

In this study, Na-mordenite was used as an adsorbent for the aim of removing Cn （Ⅱ ） ions from the aqueous solutions and the effects of contact time, temperature, initial metal ion eoneentratinns, initial solution pH, adsorbent d.sage arid ionic strength in the, adsorption process were investigated in detail. Experimental results showed that the snrption process follows pseudn-seeond-order kinetics very welt, the correlation coefficients R2 all reached 0.999, and the rate constant of this kinetics model for the adsorption processes, ks, increased with the increasing temperatures. The isothermal data couht be well described by the Langmuir, Freundlieh, Dubinin-Radushkevich （D-R） adsorption isothermal equations, The thermodynamic parameter, △G^°〈0, was negative, indicating that the nature of adsorption process is spoutaue.us, △G^°〈0 being positive, showing the endothermic nature of the adsorption process. This adsorption processes were dominated by the ion exchange. The amount of adsorbed copper ions increased with the increasing initial metal ion concentration and solution pH in the examined range, but decreased with the increasing dosage of adsorbent and ionic strength.