【作者】 黄伟；

【导师】 王晖；

【作者基本信息】 中南大学 ， 化学工程， 2022， 硕士

【摘要】 微塑料在水体环境中广泛存在,由于其尺寸小、比表面积大,使得它具有容易富集其他水体污染物的特征。吸附的污染物会伴随食物链的传递,对动物和人体健康造成危害,因而近年来受到广泛关注。关于微塑料与重金属和有机污染物的相互作用机制已有多项研究。本文以对生物体具有重要影响的非金属污染物硼和磷为研究对象,考查硼和磷在不同种类微塑料表面的吸附行为及其影响因素,探索水生环境中硼和磷的阴离子污染物与微塑料间的相互作用机理,从而为更广泛范围内的微塑料生态风险预测提供依据。在硼与聚氯乙烯（PVC）和聚苯乙烯（PS）微塑料上吸附行为的研究中,通过动力学和等温线模型模拟吸附行为,利用单因素实验考察包括一些水性因素如p H值、腐植酸、Na⁺离子强度、金属离子类型(Mg²⁺、Ca²⁺、Cu²⁺和Al³⁺),以及海水环境对吸附行为的变化。微塑料吸附能力顺序为:老化PVC（0.91 mg/g）>老化PS（0.197 mg/g）>原生PVC树脂（0.1 mg/g）>原生PS树脂（0.005mg/g）。吸附动力学和等温线模型表明微塑料对硼为单层吸附和化学吸附。由于硼酸（B（OH）₃）的络合和水解,腐殖酸和高p H显著抑制了吸附。金属离子的存在可能会增强或阻碍吸附,这取决于硼的存在形式、离子浓度、离子类型和微塑料类别。相互作用主要取决于B（OH）₃与微塑料表面含氧基团的表面络合。由于老化的微塑料含有更多的含氧基团,它们可以结合更多的B（OH）₃。在水生环境中,金属离子可能占据这些结合位点,硼酸盐（[B（OH）₄^-）和微塑料之间的静电力将优先。微塑料在温血动物的模拟肠道中具有最大的硼解吸率。在磷与PVC,PS和聚对苯二甲酸乙二醇酯（PET）微塑料上吸附行为的研究中,从吸附动力学和吸附热力学两个方面对吸附行为进行分析,并通过单因素实验评估不同的p H值、腐殖酸浓度和离子强度等因素对磷在微塑料上累积的风险。微塑料的吸附能力依次为:PVC（0.221 mg/g）>PS（0.21 mg/g）>PET（0.12 mg/g）。吸附动力学和等温线模型表明微塑料对磷为单层吸附和化学吸附。高p H值会造成电荷排斥而抑制微塑料的吸附,腐植酸会竞争吸附位点而显著降低了吸附能力,离子强度极大的增强了微塑料的吸附能力。微塑料对磷主要吸附剂是磷酸二氢根（H₂PO₄^-）与磷酸氢根(HPO₄^2-),微塑料表面的含氧基团如羧基和羟基等官能团上的氢可以介导H₂PO₄^-,并与磷酸盐阴离子形成氢键而相互作用。微塑料与H₂PO₄^-之间也存在一定的静电相互作用和特异性作用。通过上述结果可以对微塑料的生态风险进行预测:微塑料在土壤环境中会对许多植物的根部造成损伤,影响植物对微量元素硼和大量元素磷的吸收;在水生环境中对磷的富集可能会造成水体片区的富营养化而污染水质,对硼的富集会可能抑制植物的细胞分裂和伸长。载有硼的微塑料被水生生物所摄入并随着食物链而传递会对人体造成危害。图34幅,表10个,参考文献115篇更多还原

【Abstract】 Microplastics are widely prevalent in the water environment.Due to their small size and large specific surface area,they have the characteristics of efficiently enriching other water pollutants.The adsorbed contaminants will accompany the transmission of the food chain and cause harm to the health of all animals and humans in the food chain,so they have also received extensive attention in recent years.This paper taked the non-metallic pollutants boron and phosphorus as the research object that have an important impact on living organisms and investigated the adsorption behavior of boron and phosphorus on the surface of different types of microplastics and their influencing factors,explored the interaction mechanism between boron and phosphorus anionic pollutants and microplastics in the aquatic environment,thereby providing a basis for the prediction of microplastics ecological risk in a wider range.In the research on the adsorption behavior of boron on polyvinyl chloride（PVC）and polystyrene（PS）microplastics,we explored the adsorption behavior by kinetics,isotherm models,and several aqueous factors,including p H,humic acid,ionic strength（Na⁺）,metal ion types(Mg²⁺,Ca²⁺,Cu²⁺,and Al³⁺),and the seawater environment.The adsorption kinetics and isotherm models suggested the adsorption of boron is monolayer adsorption and chemisorption.Humic acid and high p H significantly inhibited the adsorption due to the complexation and hydrolysis of boric acid（B（OH）₃）,respectively.The presence of metal ions may enhance or hinder adsorption,depending on the boron species,ion concentration,ion type,and microplastics categories.The unique interaction mainly depended on surface complexations of B（OH）₃ with oxygen-containing groups on microplastics surface.Because aged microplastics have more oxygen-containing groups,they can combine more B（OH）₃.In the aquatic environment,metal ions may occupy these binding sites,so the electrostatic force between borate（[B（OH）₄]^-）and microplastics will take precedence.Microplastics have the greatest boron desorption rate in the simulated gut of warm-blooded animals.In the study of the adsorption behavior of phosphorus on PVC,PS,and polyethylene terephthalate（PET）microplastics,the adsorption behavior was analyzed in terms of adsorption kinetics and adsorption thermodynamics,and through single-factor experiments to evaluate different p H values,humic acid,and ionic strength affect the risk of phosphorus accumulation on microplastics.The adsorption capacity of microplastics was in the following order:PVC（0.221 mg/g）>PS（0.21mg/g）>PET（0.12 mg/g）.The adsorption kinetics and isotherm models suggested the adsorption of phosphorus is monolayer adsorption and chemisorption.High p H caused charge repulsion and inhibited the adsorption of microplastics.Humic acid could compete for adsorption sites and significantly reduce the adsorption capacity.The ionic strength greatly enhanced the adsorption capacity of microplastics.The main adsorbents of microplastics for phosphorus are dihydrogen phosphate（H₂PO₄^-）and hydrogen phosphate(HPO₄^2-).Hydrogen on functional groups such as carboxyl and hydroxyl groups on the surface of microplastics can mediate H₂PO₄^-and interact with phosphate anions by forming hydrogen bonds.There were also certain electrostatic interactions and specific effects between microplastics and H₂PO₄^-.In summary,the ecological risk of microplastics can be predicted:in the soil environment,it will cause damage to the roots of many plants,affecting the absorption of microelement boron and macroelement phosphorus by plants.In the aquatic environment,the enrichment of phosphorus may cause eutrophication of water body areas and pollutes the water quality,and the enrichment of boron may inhibit the cell division and elongation of plants.Boron-laden microplastics are harmful to humans when ingested by aquatic organisms and passed down the food chain.更多还原