摘要
新兴污染物微塑料被证实可吸附传统重金属污染物镉(Cd),而其在自然环境中不可避免地经历老化过程而发生改变,目前囊括多种材质的微塑料并涉及关键的老化作用对其吸附Cd影响的综合性和机制性的研究仍缺乏.选取PS、ABS、PP、PVC和PET等5种代表性的微塑料,通过紫外辐射法进行老化,全面对比了老化前后微塑料比表面积、结晶度、表面官能团和表面元素等理化性质的变化,以及其对Cd的等温吸附过程的差异,探讨了相关影响机制.结果表明:①微塑料老化后比表面积未发生显著改变,但结晶度显著降低.表面官能团也发生了一定的变化,尤其是C-O和O-C=O官能团比例增加,且总O含量以及O/C显著增加.②Langmuir模型能很好地拟合老化前后微塑料对Cd的等温吸附过程.老化作用增加了微塑料对Cd的吸附能力,其饱合吸附量极显著增大.老化前微塑料对Cd的饱合吸附量排序为:ABS(0.2284 mg·g^(-1))>PVC(0.1360 mg·g^(-1))>PS(0.1286 mg·g^(-1))>PP(0.1005 mg·g^(-1))>PET(0.0462 mg·g^(-1)).老化后则变为:PS(0.2768 mg·g^(-1))>ABS(0.2586 mg·g^(-1))>PVC(0.1776 mg·g^(-1))>PP(0.1721 mg·g^(-1))>PET(0.0951 mg·g^(-1)).③结晶度和表面官能团综合地影响着微塑料对Cd的吸附.原始微塑料的结晶度与其对Cd的饱合吸附量呈极显著负相关.老化作用引起的微塑料表面含氧官能团增加也是导致其对Cd的吸附能力增强的重要原因.研究成果将为更深入地认知自然界中微塑料与传统重金属污染物间相互作用的环境行为提供有科学价值的信息.
It has been verified that,as an emerging contaminant,microplastics are capable of adsorbing certain traditional contaminants like the heavy metal Cd.However,the majority of previous studies only focused on certain types of virgin microplastics,especially for PE and PS.In addition,this adsorption process might be affected by microplastics inevitably undergoing aging and consequent changes in the natural environment.Unfortunately,the relevant reports on aging effects were mainly about organic pollutants,rather than heavy metals.By far,there have been few comprehensive and mechanistic studies on the key aging effects on the Cd adsorption by various types of microplastics.In this study,five representative types of microplastics(i.e.,PS,ABS,PP,PVC,and PET)were selected for aging by ultraviolet radiation,and the physicochemical properties of virgin and aged microplastics were thoroughly compared,including specific surface area,crystallinity,surface functional groups,and surface elements.Accordingly,the changes in adsorption isotherms of Cd by microplastics were discussed.The results showed that:①aging induced non-significant changes in specific surface area but a significant decrease in crystallinity.Surface functional groups also changed,including the emergence of a C=O functional group on PS and ABS,the decrease in C=C absorption peak intensity on ABS,and the increase in absorption peak intensities of C=O,C-O,and polar ester groups on PET.Regarding surface C content,C=C/C-C decreased,whereas C—O and O—C=O increased.The total O content and O/C significantly increased as well.②The Langmuir model well-fitted the adsorption isotherms of Cd by virgin and aged microplastics.Aging significantly expanded the adsorption capacity of Cd by microplastics,as the order of saturated adsorption capacity before aging was ABS(0.2284 mg·g^(-1))>PVC(0.1360 mg·g^(-1))>PS(0.1286 mg·g^(-1))>PP(0.1005 mg·g^(-1))>PET(0.0462 mg·g^(-1))and then became PS(0.2768 mg·g^(-1))>ABS(0.2586 mg·g^(-1))>PVC(0.1776 mg·g^(-1))>PP(0.1721 mg·g^(-1))>PET(0.0951 mg·g^(-1))after aging.③Both crystallinity and surface functional groups played key roles in the adsorption of Cd by microplastics.As for virgin microplastics,crystallinity was negatively correlated with the saturated adsorption capacity of Cd,because the amorphous regions contributed most to Cd adsorption.Aging brought about the decrease in crystallinity and the increase in amorphous regions,which further promoted the oxidation reaction on microplastics.Consequently,oxygen-containing functional groups increased on the surface and eventually expanded the adsorption capacity of Cd by microplastics.Note that certain specific functional groups of various microplastics also had impacts on the adsorption process.These results provide valuable information about the environmental behaviors and interactions of microplastics and heavy metals in nature.
作者
王俊杰
陈晓晨
李权达
金成俊
黄艺佳
范露健
张剑宇
刘宪华
徐开钦
WANG Jun-jie;CHEN Xiao-chen;LI Quan-da;JIN Cheng-jun;HUANG Yi-jia;FAN Lu-jian;ZHANG Jian-yu;LIU Xian-hua;XU Kai-qin(Fujian Provincial Engineering Research Center of Rural Waste Recycling Technology,College of Environment and Safety Engineering,Fuzhou University,Fuzhou 350108,China;The Nuclear Industry 247 Brigade of Tianjin North China Geological Exploration Bureau,Tianjin 301800,China;College of New Energy and Environment,Jilin University,Changchun 130021,China;Jiangsu Longchang Chemical Co.,Ltd.,Rugao 226532,China;School of Environmental Science and Engineering,Tianjin University,Tianjin 300072,China;Fujian Ospring Technology Development Co.,Ltd.,Fuzhou 350000,China;National Institute for Environmental Studies,Tsukuba 305-8506,Japan)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2022年第4期2030-2038,共9页
Environmental Science
基金
国家自然科学基金项目(41807116)
福建省自然科学基金项目(2019J05035)。
关键词
老化作用
微塑料
吸附
镉(CD)
机制
结晶度
表面官能团
aging effect
microplastics
adsorption
Cd
mechanism
crystallinity
surface functional group
作者简介
王俊杰(1997-),男,硕士研究生,主要研究方向为微塑料污染的环境风险,E-mail:N190627053@fzu.edu.cn;通信作者:陈晓晨,E-mail:chenxiaochen@fzu.edu.cn。
