Manju G N, Anoop Krishnan K, Vinod V P, Anirudhan T S
Department of Chemistry, University of Kerala, Kariavattom, Trivandrum 695581, India.
J Hazard Mater. 2002 Apr 26;91(1-3):221-38. doi: 10.1016/s0304-3894(01)00392-2.
An adsorbent for heavy metals was synthesized by introducing carboxylate functional group into polyacrylamide-grafted hydrous iron(III) oxide. The product exhibits a very high adsorption potential for Pb(II), Hg(II) and Cd(II). The removal of metal ions by adsorption on adsorbent has been found to be contact time, concentration, pH and temperature dependent. The process follows first-order reversible kinetics. The intraparticle diffusion of metal ions through pores in the adsorbent was shown to be the main rate-limiting step. The optimum pH range for the removal of metal ions was found to be 5.0-6.0. The thermodynamic parameters such as free energy change, enthalpy change and entropy change have been calculated to predict the nature of adsorption. The adsorption data were fitted using the Langmuir equation and maximum adsorption for each metal was estimated using their respective Langmuir equation constants. The method was applied for synthetic wastewaters. NaCl regeneration has been tried for several cycles with a view to recover the adsorbed metal ions and also to restore the sorbent to its original state.
通过将羧酸根官能团引入聚丙烯酰胺接枝的水合氧化铁中合成了一种重金属吸附剂。该产品对Pb(II)、Hg(II)和Cd(II)表现出非常高的吸附潜力。已发现通过吸附剂吸附去除金属离子与接触时间、浓度、pH值和温度有关。该过程遵循一级可逆动力学。金属离子通过吸附剂孔隙的颗粒内扩散被证明是主要的限速步骤。发现去除金属离子的最佳pH范围为5.0 - 6.0。已计算出自由能变化、焓变和熵变等热力学参数以预测吸附的性质。使用朗缪尔方程拟合吸附数据，并使用各自的朗缪尔方程常数估算每种金属的最大吸附量。该方法应用于合成废水。为了回收吸附的金属离子并使吸附剂恢复到原始状态，已尝试进行了几个循环的NaCl再生。
