摘要
选取环境中5种典型微塑料聚氯乙烯(PVC)、聚丙烯(PP)、聚苯乙烯(PS)、聚乙烯(PE)和聚对苯二甲酸乙二酯(PET),研究其对重金属镉离子(Cd^(2+))的吸附行为及影响因素。结果表明,微塑料对Cd^(2+)的吸附动力学更符合准二级动力学模型,吸附平衡时的吸附量由大到小顺序为PVC、PP、PS、PET、PE。微塑料比表面积与Cd^(2+)吸附量表现为显著正相关,比表面积是影响Cd^(2+)吸附的重要性质,而微塑料的其他性质(如结晶度、特殊官能团)也会对Cd^(2+)吸附产生影响。弗伦德利希(Freundlich)和朗格缪尔(Langmuir)模型均能较好拟合这几种微塑料对Cd^(2+)的等温吸附行为,对Cd^(2+)存在着单层和多层吸附且是非均质吸附过程。环境因素pH值、温度和共存重金属离子均会对吸附过程产生影响,pH值在3.0~7.0时,微塑料对Cd^(2+)吸附量先增加后减少,PS微塑料在pH值为5.0时吸附量最大,其他微塑料pH值为6.0时吸附量最大;微塑料对Cd^(2+)的吸附属于吸热过程,随吸附体系温度增加(15~35℃)吸附量也增加;共存重金属铅离子(Pb^(2+))或铜离子(Cu^(2+))会与Cd^(2+)产生竞争吸附而减少微塑料对Cd^(2+)的吸附,Pb^(2+)的竞争吸附作用要大于Cu^(2+)。静电引力作用是这5种微塑料吸附Cd^(2+)的主要机制。
Microplastics,as heavy metals vectors,have been proved to be able to adsorb heavy metals.However,there is a lack of comparative study on the effects of different types of microplastics.Therefore,five typical microplastics,including polyvinyl chloride(PVC),polypropylene(PP),polystyrene(PS),polyethylene(PET),and polyethylene terephthalate(PET),were selected to study their adsorption behavior for cadmium ion(Cd^(2+))and influencing factors.The surface morphology,specific surface area(SSA),crystallinity,and surface functional groups of microplastics were also tested.The results show that the Pseudo-second-order model can better fit the adsorption process,and the adsorption capacities follow the order of PVC>PP>PS>PET>PE.A significant positive correlation between the SSA of microplastics and Cd^(2+)adsorption amount is observed,indicating that SSA is an important property affecting Cd^(2+)adsorption;however,other properties of microplastics(i.e.,crystallinity and special functional groups)would also affect Cd^(2+)adsorption.Freundlich and Langmuir isothermal adsorption equations can both describe the adsorption isothermal,indicating monolayer and multilayer adsorption processes occur in the adsorption system,as well as heterogeneous adsorption.Finally,our results demonstrate that environmental factors(i.e.,pH,temperature,and coexisted heavy metal ions)affect the adsorption processes.The adsorption capabilities of Cd^(2+)onto the microplastics first increase and then decrease with increasing pH from 3.0 to 7.0,which obtain the maximum adsorption capacity for PS and other microplastics when pH was 5.0 and 6.0,respectively.The adsorption was an endothermic process,thus the adsorption capacity increased with increasing temperature(from 15℃to 35℃).Because of competitive adsorption,the coexisted Pb^(2+)or Cd^(2+)decreased Cd^(2+)adsorption by microplastics,and the competitive effect was greater for Pb^(2+)than that of Cu^(2+).Electrostatic attraction is the main mechanism for the adsorption of Cd^(2+)by microplastics.
作者
陈春乐
刘雅慧
田甜
CHEN Chunle;LIU Yahui;TIAN Tian(College of Environment and Safety Engineering,Fuzhou University,Fuzhou 350108,China;School of Resources and Chemical Engineering,Sanming University,Sanming 365004,Fujian,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2023年第6期2081-2089,共9页
Journal of Safety and Environment
基金
国家自然科学基金项目(41801279)
福建省自然科学基金项目(2021J011115)
福建省中青年教师教育科研项目(JAT200636)
2021年国家级与省级大学生创新创业训练计划项目(202111311018)。
作者简介
陈春乐,副教授,从事环境化学与污染生态研究,cclchina.ch@163.com。
