老化微塑料对Hg(Ⅱ)的吸附解吸行为及机理研究  

Studies of Behavior and Mechanism of Hg (Ⅱ) Adsorption-Desorption onto Aged Polystyrene

作　　者：薛彬 蓝文陆 林海英 冯庆革 韦俊麒 陆一娇 XUE Bin;LAN Wenlu;LIN Haiying;FENG Qingge;WEI Junqi;LU Yijiao(School of Resources,Environment and Materials,Guangxi University,Nanning 530004,China;Marine Environmental Monitoring Centre of Guangxi,Beihai 536000,China;Guangxi Universities Key Lab of Environmental Protection,Guangxi University,Nanning 530004,China)

机构地区：[1]广西大学资源环境与材料学院,广西南宁530004 [2]广西壮族自治区海洋环境监测中心站,广西北海536000 [3]广西大学广西高校环境保护重点实验室,广西南宁530004

出　　处：《环境科学与技术》2022年第8期31-37,共7页Environmental Science & Technology

基　　金：国家自然科学基金地区项目:基于薄膜扩散梯度技术测定河口区溶解态Hg(Ⅱ)方法的建立、影响因素及机理、矫正模型研究(22166006);广西自然科学基金项目:以半胱氨酸改性氧化石墨烯作为DGT结合相的研发及用于富集海水中溶解态无机汞研究(2020GXNSFAA297011)。

摘　　要：近年来研究者一直关注老化微塑料与常见重金属如镉、铬、铅等的相互作用,而它与高毒性Hg(Ⅱ)相互作用机制并未清晰。该研究以聚苯乙烯(PS)为目标塑料,利用臭氧对PS进行老化,利用批量吸附实验结合SEM、FT-IR、Zeta电位、接触角等表征手段,探究PS老化前后对Hg(Ⅱ)的吸附-解吸行为及机制。结果表明,臭氧老化后的PS(简称PS-O_(3))表面粗糙度增加,出现新的官能团羰基,接触角从127.2°降至72.8°,亲水性明显增强。PS-O_(3)与Hg(Ⅱ)的吸附行为符合准二级动力学、Langmuir等温模型,提示以单层的化学反应为主,理论最大吸附量为15.78 mg/g,高于原始PS的7倍,这主要归功于静电吸引、含氧官能团与汞的络合作用。此外,老化PS在胃液环境下解吸率(约54%)约是纯水条件的60倍,约是原始塑料的10倍;与0.04%HCl、海水介质中的类似,高解吸量可分别追溯于胃蛋白酶对Hg(Ⅱ)的高亲和力、酸中大量的H^(+)、海水中阳离子的竞争作用;此结果揭示了老化后的微塑料可富集水中Hg(Ⅱ),在酸性、高盐环境中可释放Hg(Ⅱ),成为Hg(Ⅱ)迁移转化过程的载体。研究老化微塑料对水环境中Hg(Ⅱ)的吸附-解吸行为及作用机制,为了解微塑料与重金属协同迁移、处理提供基础数据。In recent years,the interaction between aged micro-plastics and heavy metals such as cadmium,chromium and lead,has been one of the hot topics of the researchers,and the interaction mechanism between aged micro-plastics and highly toxic heavy metal Hg(Ⅱ)was yet unrevealed.In this laboratory experimental study,polystyrene(PS)being aged by ozone was selected as the target micro-plastics,and with the combination of batch adsorption experiment and characterization using instruments including SEM,FT-IR,Zeta potential and contact angles,the adsorption-desorption behavior and mechanism of Hg(Ⅱ)and the PS(before and after O_(3) aging)were explored.The findings of the lab experiment indicated that the ozone-aged PS(PS-O_(3))presented increased surface roughness,decreased contact angles(from 127.2°to 72.8°),and significantly enhanced surface hydro-philicity,in addition,a new carbonyl group appeared.The process of Hg(Ⅱ)adsorption onto PS-could be well described by the pseudo-second-order kinetics and Langmuir isothermal model,which suggested the single-layer chemical reaction was mainly involved;it was also showed that the maximum adsorption capacity of PS-O_(3) was estimated to be 15.78 mg/g,seven times greater than that of the original PS(without O_(3) aging),this fact was mostly attributed to the electrostatic attraction and complexation between the oxygen-containing group and Hg(Ⅱ).Moreover,PS-O_(3) desorption rate(c.a 54%)in the environment of gastric fluid(analogous to seawater of 0.04% HCl)was 60 times that in ultra-pure water,10 times that of the original plastic in gastric fluid:the remarkable desorption capacity could be traced to the high affinity of gastric fluid towards Hg(Ⅱ),the competitive effect from numerous H^(+) in the 0.04% HCl,and the abundant cations in seawater.In short,aged microplastics could enrich the aquatic Hg(Ⅱ),on other hand,Hg(Ⅱ)would be released in the acidic and hyperhaline environment.So,the aged microplastics could act as the carrier in the migration and transformation of H

关 键 词：聚苯乙烯 臭氧老化 Hg(Ⅱ) 机理探究 

分 类 号：X52[环境科学与工程—环境工程]