羧甲基纤维素改性纳米钯铁双金属去除水中2,4-二氯苯酚的影响因素及机理  

Influencing factors and mechanisms of removal of 2,4-dichlorophenol in water by nano-palladium-iron bimetal modified by carboxymethyl cellulose

作　　者：钟金魁[1,2] 齐永辉 谢欣卓 李静 郑博文 王立果 ZHONG Jinkui;QI Yonghui;XIE Xinzhuo;LI Jing;ZHENG Bowen;WANG Liguo(School of Environmental and Municipal Engineering,Lanzhou Jiaotong University,Lanzhou Gansu 730070;Key Laboratory of Yellow River Water Environment in Gansu Province,Lanzhou Gansu 730070)

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 [2]甘肃省黄河水环境重点实验室,甘肃兰州730070

出　　处：《环境污染与防治》2023年第2期133-138,144,共7页Environmental Pollution & Control

基　　金：国家自然科学基金资助项目(No.22166022);甘肃省科技计划资助项目(No.20JR2RA002);兰州交通大学大学生科技创新资助项目(No.DXS2022-035)。

摘　　要：利用液相还原法制备了纳米零价铁(nZVI)、纳米钯铁双金属(Pd/Fe)、羧甲基纤维素(CMC)改性nZVI(CMC-Fe)和CMC改性钯铁双金属(CMC-Pd/Fe)4种铁基纳米材料,并用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对其进行了表征。研究了这4种材料对水中2,4-二氯苯酚(2,4-DCP)的表观去除率,考察了铁基纳米材料投加量、Pd负载量、溶液初始pH及污染物浓度等因素对CMC-Pd/Fe去除2,4-DCP的影响,并探讨了可能的作用机理。结果表明,在4种材料中,CMC修饰的CMC-Pd/Fe的分散性最好,粒径明显小于未用CMC修饰的nZVI和Pd/Fe。4种材料对2,4-DCP的表观去除率为CMC-Pd/Fe>CMC-Fe>Pd/Fe>nZVI。随着CMC-Pd/Fe投加量和Pd负载量的增加,CMC-Pd/Fe对2,4-DCP的表观去除率增大,而随着2,4-DCP浓度的升高,CMC-Pd/Fe对2,4-DCP的表观去除率下降。当溶液初始pH=3、5和7时,CMC-Pd/Fe对2,4-DCP的表观去除率分别为94.34%、99.50%和96.62%;但当溶液初始pH=11时,其表观去除率仅为51.28%,这主要是由于在碱性条件下,带负电的2,4-DCP与CMC的静电排斥作用远大于π-π共轭吸附作用,阻碍了CMC-Pd/Fe的电子向污染物传递,导致2,4-DCP表观去除率下降。Four types of iron-based nano-materials,which were nano-zero-valent iron(nZVI),nano-palladium-iron bimetal(Pd/Fe),nZVI modified by carboxymethyl cellulose(CMC-Fe)and nano Pd/Fe modified by CMC(CMC-Pd/Fe),were prepared by liquid phase reduction method,and characterized by scanning electron microscope(SEM),and X-ray diffraction(XRD).The apparent removal efficiencies of the above four iron-based nano-materials on 2,4-dichlorophenol(2,4-DCP)in water were studied.The effects of iron-based nano-materials dosage,the loading amounts of palladium,the initial pH in solution and mass concentration of pollutant on apparent removal efficiency of 2,4-DCP were investigated.The possible mechanisms involved in the reaction were also explored.The results showed that the particle size of CMC-Pd/Fe with CMC was significantly smaller than those of nZVI and Pd/Fe without CMC,and its dispersibility was also the best in the four iron-based nano-materials.The sequence of apparent removal efficiency of 2,4-DCP was CMC-Pd/Fe>CMC-Fe>Pd/Fe>nZVI.The apparent removal efficiency of 2,4-DCP by CMC-Pd/Fe increased with the increase of CMC-Pd/Fe dosage and palladium loading amounts,while decreased with the increase of mass concentration of 2,4-DCP.The apparent removal efficiency of CMC-Pd/Fe for 2,4-DCP was 94.34%,99.50%and 96.62%when the initial pH in solution was 3,5 and 7,respectively.However,when the pH was 11,the apparent removal efficiency of 2,4-DCP was only 51.28%because electrostatic repulsion was overwhelmingly higher thanπ-πconjugated adsorption interaction between 2,4-DCP and CMC under alkaline condition.This electrostatic repulsion hindered electron transfer from CMC-Pd/Fe to 2,4-DCP,and resulted in a lower apparent removal efficiency of 2,4-DCP.

关 键 词：纳米钯铁双金属 羧甲基纤维素 2 4-二氯苯酚 表观去除率 

分 类 号：X703[环境科学与工程—环境工程]