纳米银与微塑料在模拟垃圾填埋柱中的共迁移特征

Characteristics of silver nanoparticles and microplastics co-migration in simulated landfill columns

以模拟垃圾填埋柱和人工配制渗滤液,探讨了纳米银(AgNPs)和微塑料(MPs)在垃圾填埋场中的迁移行为.结果发现,无论是单体系还是二元体系,随着填埋时间增长,AgNPs和MPs颗粒在渗滤液中稳定性增强,在填埋场中迁移能力增大,可能导致填埋中晚期有更多的污染颗粒随渗滤液流出填埋场.当AgNPs和MPs共存时,相对于单体系促进了AgNPs的迁移而轻微地抑制了MPs的迁移.结合DLVO理论和胶体过滤理论分析,一方面是由于流动性更高的MPs可作为AgNPs的载体,同时与AgNPs竞争固相介质上的吸附位点,从而促进AgNPs的迁移.另一方面,共存的AgNPs降低了MPs颗粒的表面负电荷使其稳定性减弱,并通过预沉积在固相介质上提供额外的MPs沉积位点,从而抑制MPs的迁移.

Lab-scaled simulated landfill columns and synthetic leachate were prepared to investigate the transport of silver nanoparticles(AgNPs)and microplastics(MPs)in municipal solid waste landfill.The results showed that stability of AgNPs and MPs in leachate increased with the landfill time extending while they existed in a single system as well as in a binary system.Thus the migration ability of these pollutants in the landfill was promoted so that more pollutant particles could be discharged from the middle and aged landfill along with leachate.In comparison with single system,AgNPs and MPs coexisting system facilitated the transport of AgNPs but slightly inhibited the transport of MPs.In term of DLVO theory and colloidal filtration theory,it suggests that MPs of higher mobility could serve as carriers of AgNPs and compete with AgNPs for adsorption sites on the solid media,thereby promoting the transport of AgNPs.Inversely,the coexisting AgNPs could reduce the negative surface charge on the MPs to weaken the stability of pollutants particle,and could provide additional deposit sites for MPs through AgNPs pre-deposition on the solid media,thereby inhibiting the transport of MPs.