考虑离子尺寸效应的蒙脱石双电层中阳离子和电势分布研究  

Study on cation and electronic potential distribution in montmorillonite double layer considering ion size effects

作　　者：安厚睿 彭陈亮 林福明[1,3] 王观石 龙平[1,2] 肖霞[1] AN Hourui;PENG Chenliang;LIN Fuming;WANG Guanshi;LONG Ping;XIAO Xia(School of Civil and Surveying&Mapping Engineering,Jiangxi University of Science and Technology,Ganzhou 341000,Jiangxi,China;Jiangxi Key Laboratory of River Source Water Ecological Protection,Jiangxi University of Science and Technology,Ganzhou 341000,Jiangxi,China;School of Science,Jiangxi University of Science and Technology,Ganzhou 341000,Jiangxi,China)

机构地区：[1]江西理工大学土木与测绘工程学院,江西赣州341000 [2]江西理工大学河流源头水生态保护江西省重点实验室,江西赣州341000 [3]江西理工大学理学院,江西赣州341000

出　　处：《有色金属科学与工程》2024年第6期952-962,共11页Nonferrous Metals Science and Engineering

基　　金：国家自然科学基金资助项目(52364015);江西省双千计划项目(jxsq2023201013);江西省自然科学基金项目(20212BAB211012);江西省高等学校井冈学者特聘教授岗位资助项目;江西理工大学清江青年英才支持计划资助项目(JXUSTQJYX2020009)。

摘　　要：离子型稀土矿浸出是一个双电层重新平衡的过程,离子尺寸效应对双电层中阳离子和电势分布具有重要影响。本文基于Gouy-Chapman-Stern双电层模型,考虑了离子大小对体系静电自由能所产生的影响,耦合了考虑离子尺寸效应的非线性Boltzmann方程与泊松方程,建立了sPB方程;利用该耦合方程研究了离子尺寸效应对双电层中离子和电势的分布影响,结合经典Poisson-Boltzmann方程(cPB)的计算结果,与杯浸试验结果进行了对比分析。结果表明:NH_(4)^(+)和La^(3+)在蒙脱土表面的吸附存在差异,蒙脱土对NH_(4)^(+)和La^(3+)的饱和吸附量试验值分别为0.635 mmol/g和0.305 mmol/g。基于cPB方程,NH_(4)^(+)和La^(3+)的计算吸附量分别是实际的17倍和11倍;而基于sPB方程,NH_(4)^(+)和La^(3+)的计算吸附量分别为1.75倍和1.25倍。sPB方程所计算的Stern电势小于cPB方程的计算值,且sPB方程所计算的Stern电势随浓度的变化程度不大。离子水化作用对离子的吸附量和Stern电势的变化几乎没有影响。综上,考虑离子尺寸效应的sPB方程能更好描述双电层内阳离子和电势分布情况。The leaching of ionic rare earth is a process of rebalancing the electric double layer,and the ion size effects have an important influence on the cation and potential distribution in the electric double layer.This article coupled the nonlinear Boltzmann equation considering ion size effects with the Poisson equation(sPB)by taking into account the influence of ion size on the system's electrostatic free energy,based on the Gouy-Chapman-Stern double-layer model.This coupling equation was used to study the effects of ion size on the distribution of ions and electric potential in the double layer.Combined with the results of cup leaching experiments,the calculation results were compared and analyzed with the classical Poisson Boltzmann equation(cPB).The results showed that there were differences in the adsorption of NH_(4)^(+)and La^(3+)on the surface of montmorillonite,and the measured saturated adsorption amounts were 0.635 mmol/g and 0.305 mmol/g,respectively.Based on the cPB equation,the calculated adsorption amounts of NH_(4)^(+) and La^(3+)were about 17 times and 11 times the actual adsorption amounts,respectively.However,according to the sPB equation,they were about 1.75 times and 1.25 times,respectively.The Stern potential calculated by the sPB equation was significantly lower than that by the cPB equation,and the variation of the Stern potential calculated by the sPB equation with concentration was not significant.Ionic hydration had little effect on ion adsorption capacity and Stern potential.Overall,the sPB equation considering ion size could better describe the distribution of cations and electric potential within the electric double layer.

关 键 词：离子型稀土 双电层 离子尺寸效应 阳离子分布 电势分布 

分 类 号：O646[理学—物理化学] O647[理学—化学] S153[农业科学—土壤学]