污泥腐殖酸对Cd^2+的吸附特性  

Adsorption Properties of Sludge-Based Humic Acid to Cd^2+

作　　者：张康 戴亮[1] 赵伟繁 王刚[1] 未碧贵[1] 任珺 ZHANG Kang;DAI Liang;ZHAO Weifan;WANG Gang;WEI Bigui;REN Jun(School of Environmental and Municipal Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学环境与市政工程学院,甘肃兰州730070

出　　处：《环境科学研究》2020年第6期1459-1468,共10页Research of Environmental Sciences

基　　金：国家自然科学基金项目(No.51668034,31560234);甘肃省教育厅高等学校创新能力提升项目(No.2019B-051)。

摘　　要：为了促进污水处理厂剩余污泥的资源化利用,探索S-HA(sludge-based humic acid,污泥腐殖酸)对溶液中重金属Cd^2+的吸附特性.采用国际腐殖酸协会(IHSS)推荐的方法提取S-HA,通过元素分析、FT-IR(傅里叶红外光谱分析)和SEM-EDS(外观形态分析)等方法,考察溶液pH和共存阳离子对吸附过程的影响,并对吸附过程分别进行了吸附动力学模型、等温吸附模型和吸附热力学模型拟合,同时通过对比S-HA吸附前后的红外光谱和扫描电镜-能谱图片,探索S-HA对Cd^2+的吸附机制.结果表明:①S-HA表面呈松散的簇团状,含有大量的羧基、醇羟基和酚羟基等含氧官能团,芳香度较高,含有较多的脂肪链结构;S-HA在吸附水中Cd^2+的过程中,Cd^2+与S-HA表面上的酚羟基、羧基等官能团发生了络合作用.②S-HA对Cd^2+的吸附量随溶液pH升高而增加,溶液中Na^+、NH4^+和Ca^2+等共存阳离子的存在不利于S-HA对Cd^2+的吸附,其中Ca^2+的存在对S-HA吸附Cd^2+影响最大.③S-HA对Cd^2+的吸附由快吸附、慢吸附和吸附平衡3个阶段组成,吸附平衡时间为12 h;吸附过程符合准二级动力学模型,其整体吸附速度由液膜扩散和颗粒内扩散共同控制;吸附等温线符合Freundlich等温吸附模型,25℃下的最大吸附量为19.29 mg g,Cd^2+在S-HA上的吸附是自发吸热反应.研究显示:污水处理厂剩余污泥提取的S-HA对Cd^2+具有较好的吸附效果;S-HA对Cd^2+的吸附过程同时存在着物理吸附和化学吸附;高pH对S-HA吸附Cd^2+有促进作用,而高离子强度对S-HA吸附Cd^2+有抑制作用.In order to promote the resource utilization of excess sludge in sewage treatment plants,the adsorption characteristics of sludge-based humic acid(S-HA)to Cd^2+were explored.S-HA was extracted using the method recommended by International Humic Substances Society(IHSS).The S-HA was characterized by elemental analysis,infrared spectroscopic analysis and morphology analysis.The effects of solution pH and coexisting cations on Cd^2+adsorption were investigated.The adsorption process was fitted with adsorption kinetic model,isothermal adsorption model and adsorption thermodynamic model.Meanwhile,the adsorption mechanism of Cd^2+on S-HA was explored by comparing the infrared spectra and the images and results of scanning electron microscopy-energy dispersive X-ray analysis before and after Cd^2+adsorption on S-HA.The results showed that:(1)The surface of S-HA was loose cluster,containing a large number of oxygenic functional groups,such as carboxyl groups,alcoholic hydroxyl groups and phenolic hydroxyl groups,with a high degree of aromaticity and more fatty chain structure;Cd^2+complexed with phenolic groups and carboxyl groups on the surface of S-HA.(2)As the pH increased,the adsorption of Cd^2+on S-HA increased gradually.The presence of co-existing cations such as Na^+,NH4^+and Ca^2+in solution was adverse to the adsorption of Cd^2+by S-HA,and Ca^2+had the greatest effect on the adsorption of Cd^2+by S-HA.(3)The adsorption process of Cd^2+by S-HA included three stages:fast adsorption,slow adsorption and adsorption equilibrium,and the adsorption equilibrium time was 12h.The adsorption process was fitted by the pseudo-second order kinetic model,and the overall adsorption rate was controlled by both liquid membrane diffusion and intra-particle diffusion.The adsorption isotherm agreed with the Freundlich isothermal adsorption model,with a maximum adsorption capacity of 19.29 mg g at 25℃.The adsorption of Cd^2+on S-HA was a spontaneous endothermic reaction.The results show that the S-HA extracted from the sludge of the

关 键 词：污泥 腐殖酸 吸附 CD^2+ 

分 类 号：X703.5[环境科学与工程—环境工程]