| 微塑料对水中铜离子和四环素的吸附行为 |
| 摘要点击 2119 全文点击 755 投稿时间：2020-02-27 修订日期：2020-03-12 |
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| 中文关键词 微塑料 吸附 铜离子 四环素 模型 |
| 英文关键词 microplastics sorption copper ions tetracycline(TC) model |
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| 中文摘要 |
| 微塑料作为载体可与水中重金属、抗生素结合进而形成复合污染，这改变了污染物原有的环境行为与危害性.微塑料与重金属及抗生素间的作用途径与机制是评价其环境风险及毒理学机制的前提.目前有关微塑料与重金属及抗生素间的相互作用机制尚不清晰.以高密度聚乙烯（HDPE）和通用级聚苯乙烯（GPPS）颗粒作为代表，研究了微塑料在单一体系和复合体系中对Cu2+和四环素的吸附行为，并就相关机制进行了探讨.结果表明，单一体系中，GPPS和HDPE分别对TC和Cu2+表现出更大的平衡吸附量；复合体系中，GPPS对Cu2+和TC的平衡吸附量均大于HDPE，且2种微塑料的吸附能力均较单一体系有所提高.准二级动力学模型对微塑料吸附过程的描述更为合理，吸附过程可划分为表面吸附和孔内扩散2个阶段.Langmuir等温吸附模型较Freundlich等温吸附模型更符合实验情形.单一体系中，GPPS和HDPE对Cu2+和TC的饱和吸附量分别为0.178、0.257、0.334和0.194 μmol·g-1，而在复合体系中，相应的饱和吸附量则分别增大至0.529、0.411、0.471和0.341 μmol·g-1.表面形态特征及化学官能团的不同是导致GPPS和HDPE吸附行为差异的主要原因.体系pH影响微塑料和吸附对象的存在形态及表面电性，继而影响平衡吸附量.环境温度在15～35℃范围时，提高温度不利于微塑料的吸附.Cu2+和TC在共存条件下可产生协同效应，络合物的形成及相互间的桥接作用使得二者更易于被微塑料吸附. |
| 英文摘要 |
| The interaction between microplastics, heavy metals, and antibiotics can lead to combined pollution, which could result in greater environmental damage. The pathway and mechanism of the interaction between microplastics, heavy metals, and antibiotics are the preconditions for evaluating the associated environmental risk; however, these are not well understood. As probe sorbates, the sorption behaviors of copper ions (Cu2+) and tetracycline (TC) on two microplastics [high density polyethylene (HPDE) and general-purpose polystyrene (GPPS)] in aqueous solution were investigated and the welding theory with relevant experimental results were discussed. The adsorption capacity of HDPE was greater than that of GPPS in a single Cu solution, whereas the reverse situation occurred in a single TC solution. Moreover, the adsorption capacity of the microplastics in a Cu2+-TC binary solution was larger than that in the single solutions. The pseudo-second-order kinetic models to describe the adsorption process were reasonable and the entire process could be divided into two phases:surface adsorption and internal diffusion. The Langmuir model provided a better fit of the data than did the Freundlich model. In the single solutions, the saturated adsorption amounts of Cu2+ and TC were 0.178 μmol·g-1 and 0.257 μmol·g-1, respectively, for GPPS, and 0.334 μmol·g-1 and 0.194 μmol·g-1, respectively, for HDPE. In the binary solution, the corresponding numerical values were 0.529 μmol·g-1 and 0.411 μmol·g-1, respectively, for GPPS and 0.471 μmol·g-1 and 0.341 μmol·g-1, respectively, for HDPE. The variations in the surface morphological characteristics and chemical functional groups were the main reasons for the difference in the adsorption behavior of microplastics. The variation of the pH of the adsorption system could change the existing forms and surface electrical properties of microplastics and adsorbed objects, and subsequently affected the equilibrium adsorption capacity. When the ambient temperature was in the range of 15 to 35℃, increasing the temperature was unfavorable for the adsorption process. Cu2+ and TC could produce a synergistic effect under the conditions of coexistence. The formation of complexes and bridging make Cu2+ and TC more easily adsorbed by microplastics. |
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