Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, PR China; Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China.
Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China.
Chemosphere. 2020 Dec;261:127592. doi: 10.1016/j.chemosphere.2020.127592. Epub 2020 Jul 18.
Ubiquitous microplastics were recognized as an ideal carrier for polycyclic aromatic hydrocarbons (PAHs) to spread in nature or transfer to biota, thus posing risks to human health. However, little is known about how the functional groups in PAH derivatives influence their sorption onto microplastics as compared to parent PAHs. This study investigated the sorption of naphthalene (NAP) and its derivatives onto polystyrene microspheres with (MP-COOH) or without (MP) surface modification of the carboxyl group. NAP derivatives with charged groups (e.g., -NH, -OH and -COOH) reached the sorption equilibrium more early than NAP and its derivative with an uncharged group (e.g., -CH), whereas their sorption capacities (K = 6.0-8.4 L/g for MP, K = 4.5-6.3 L/g for MP-COOH) were significantly lower than that of the latter (K = 11.6-12.0 L/g for MP, K = 9.4-10.0 L/g for MP-COOH). The inhibition of charged groups on sorption could be attributed to their facilitation on molecular polarity and, thus, their lower hydrophobicity (LogK) since hydrophobicity was the crucial factor controlling the sorption of NAP and NAP derivatives onto both MP and MP-COOH. Computational modeling further showed that charged functional groups would weaken the π-π interaction or strengthen the repulsion between NAP or NAP derivative molecule and MP or MP-COOH molecule, which might also contribute to the suppressed sorption. This study provides new insight into the affinity of PAH derivatives with microplastics, which, therefore, improves our understanding of the environmental fates of microplastics and the organic pollutants.
微塑料无处不在，被认为是多环芳烃（PAHs）在自然界中传播或转移到生物群的理想载体，因此对人类健康构成威胁。然而，对于 PAH 衍生物中的官能团如何影响其与微塑料的吸附，与母体 PAHs 相比，人们知之甚少。本研究调查了萘（NAP）及其衍生物在带有（MP-COOH）或不带（MP）羧基表面修饰的聚苯乙烯微球上的吸附。带有带电基团（如-NH、-OH 和-COOH）的 NAP 衍生物比 NAP 及其不带电基团（如-CH）的衍生物更早达到吸附平衡，但其吸附能力（对于 MP，K=6.0-8.4 L/g；对于 MP-COOH，K=4.5-6.3 L/g）明显低于后者（对于 MP，K=11.6-12.0 L/g；对于 MP-COOH，K=9.4-10.0 L/g）。带电基团对吸附的抑制作用可归因于它们对分子极性的促进作用，从而降低其疏水性（LogK），因为疏水性是控制 NAP 和 NAP 衍生物在 MP 和 MP-COOH 上吸附的关键因素。计算建模进一步表明，带电官能团会削弱π-π相互作用或增强 NAP 或 NAP 衍生物分子与 MP 或 MP-COOH 分子之间的排斥作用，这也可能导致吸附受到抑制。本研究为 PAH 衍生物与微塑料的亲和力提供了新的见解，从而提高了我们对微塑料和有机污染物环境命运的理解。
