氨基磷酸螯合树脂(D418)高效去除Cu(Ⅱ)的性能与机制

Performance and mechanism of the amino methylene phosphonic acid chelating resin(D418)for the efficient removal of Cu(Ⅱ)

为阐明氨基磷酸螯合树脂(D418)在水体中高效去除Cu(Ⅱ)的作用机制,通过吸附实验系统考察了pH、离子强度、接触时间、温度等因素对D418树脂去除Cu(Ⅱ)的影响,并通过吸附动力学模型、等温吸附模型和位点能量分布理论分析其去除机制。研究结果表明:Cu(Ⅱ)溶液初始pH=9.00时,Cu(Ⅱ)最大去除率达到97.20%,且Zeta电位变化对Cu(Ⅱ)去除率影响符合Boltzmann模型。离子强度在0~0.10 mol/L增加,有利于促进D418树脂去除Cu(Ⅱ)。根据线性相关系数大小比较,D418树脂吸附Cu(Ⅱ)过程最符合颗粒内扩散模型和Sips模型。以Sips模型计算热力学参数和吸附位点能量分布,D418树脂对Cu(Ⅱ)的去除为自发进行的吸热过程。Cu(Ⅱ)先占据D418树脂高能量位点,再占据低能量位点。基于XPS和FTIR数据分析,D418树脂去除Cu(Ⅱ)的机制主要是静电吸引、化学沉淀和内层络合作用。

In order to elucidate the adsorption mechanism of the amino methylene phosphonic acid chelating resin(D418)with high efficiency for removal of Cu(Ⅱ)from wastewater,the influence of pH,ionic strength,contact time and temperature were detailly investigated by adsorption experiment.Meanwhile,adsorption kinetics,adsorption isotherms and site energy distribution theory were used to explain the removal mechanism of Cu(Ⅱ)on the D418 resin.The results demonstrate that the optimal removal rate of Cu(Ⅱ)on the D418 resin reaches to 97.20%at the initial pH=9.00,and the change of zeta potential on the influence of removal rate is well compatible with Boltzmann model.Furthermore,the removal efficiency of Cu(Ⅱ)increases with the ionic strength at the range of 0-0.10 mol/L.According to the comparisons of the linear correlation coefficient values,the data of the adsorption kinetics fits well to the intra-particle diffusion while isotherm model data fits well to the Sips model.Based on the Sips model,the isotherm parameters and the energy distributions of adsorption sites were also conducted,and the result shows that the process of the Cu(Ⅱ)adsorption on the D418 resin is spontaneous and endothermic.Cu(Ⅱ)is preferentially adsorbed to the high-energy sites and to the low-energy sites.Based on the XPS and FTIR analysis,the adsorption mechanism of the Cu(Ⅱ)ions is mainly attributed to the electrostatic interaction,the chemical precipitation and the inner-sphere complexation.