不同分子量腐殖酸吸附La^(3+)的动力学实验研究  

Experimental Study on Kinetics of Adsorption of Rare Earth Ions by Humic Acid with Different Molecular Weights

作　　者：施和平[1,2,3] 耿小川 张静茹 吴瑞凤[4] SHI Heping;GENG Xiaochuan;ZHANG Jingru;WU Ruifeng(College of Science,Inner Mongolia Agricultural University,Hohhot 010018,China;Inner Mongolia Key Laboratory of Soil Quality and Nutrient Resource,Hohhot 010018,China;Key Laboratory of Agricultural Ecological Security and Green Development at Universities of Inner Mongolia Autonomous,Hohhot 010018,China;College of Chemical Engineering,Inner Mongolia University of Technology,Hohhot 010051,China)

机构地区：[1]内蒙古农业大学理学院,呼和浩特010018 [2]内蒙古土壤质量与养分资源重点实验室,呼和浩特010018 [3]农业生态安全与绿色发展自治区高等学校重点实验室,呼和浩特010018 [4]内蒙古工业大学化工学院,呼和浩特010051

出　　处：《内蒙古农业大学学报(自然科学版)》2025年第1期74-81,共8页Journal of Inner Mongolia Agricultural University(Natural Science Edition)

基　　金：国家自然科学基金项目(21167010);内蒙古自治区重点研发和成果转化计划项目(2024KJHZ0018)。

摘　　要：本文采用Na_(4)P_(2)O_(7)和NaOH法提取腐殖酸,通过加压超滤膜法截留得到6种不同分子量的腐殖酸,对腐殖酸进行表征,并采用静态吸附法研究其对La^(3+)的吸附机制,探究了浓度、时间、pH、温度和共存离子对吸附的影响。结果表明:①分子量小于4000腐殖酸碳含量较低,碳和氢含量随着分子量的增加而增加,表明不同分子量腐殖酸的组成和结构存在很大差异性;腐殖酸中的芳香度也随着分子量增加而增加,但分子量较小的腐殖酸脂肪度较高;腐殖酸总酸性基团含量随着分子量增加呈整体增加。②不同分子量腐殖酸对La^(3+)的吸附过程均符合准二级动力学方程,线性相关系数R2大于0.99,表明腐殖酸对La^(3+)的吸附主要由化学吸附机制决定;吸附符合弗罗因德利希等温吸附方程,表明为多分子层吸附。③在酸性条件下,吸附量随pH的增加而增大;碱性条件下随pH的增加而减小;但分子量最小的黄腐酸在弱酸性、中性和弱碱性条件吸附能力基本没有变化;吸附量随温度升高而减小,表明吸附反应是放热反应。④溶液中共存金属离子对腐殖酸吸附络合稀土镧离子有显著影响,存在一个浓度临界点,在低浓度时对吸附产生协同作用,而在高浓度下对吸附产生强烈的抑制作用。The humic acid was extracted by using the sodium pyrophosphate and sodium hydroxide,and six kinds of humic acid with different molecular weights were obtained by pressurized ultrafiltration membrane.The humic acid was characterized,the adsorption mechanism of La^(3+)was studied by using a static adsorption method,and the effects of concentration,time,pH,temperature and co-existing ions on the adsorption were also investigated.The results showed that,the humic acid with a molecular weight less than 4000 had low carbon content,and the content of carbon and hydrogen increased with the molecular weight increasing.The composi-tion and structure of humic acid with different molecular weights were very different.The aromaticity of humic acid also increased with the increase of molecular weight,but the fat degree of humic acid with low molecular weight was higher.The content of total acid groups in humic acid increased with the increase of molecular weight.The adsorption of La^(3+)by humic acid with different mo-lecular weights followed to a quasi-second-order kinetic equation,with a linear correlation coefficient R2 was greater than 0.99.The adsorption of La^(3+)by humic acid was mainly determined by the chemisorption mechanism.The isothermal adsorption aligned with the Freundlich model,indicating multimolecular layer adsorption.Under acidic conditions,the adsorption increased with the pH value increasing.Under alkaline condition,it decreased with the increase of pH.However,the adsorption capacity of fulvic acid with the smallest molecular weight did not change under weak acidic,neutral and weak alkaline conditions.The adsorption capacity decreased when the temperature increased,the adsorption was an exothermic process.The coexistence of metal ions in solution had a significant effect on the adsorption of complex rare earth lanthanum ions by humic acid,with a critical concentration point observed.At low concentrations,a synergistic effect on adsorption occurred,while at high concentrations,the adsorption was strongly in

关 键 词：腐殖酸 稀土离子 吸附 机制 

分 类 号：O647.32[理学—物理化学]