Abstract

Aromatic organophosphate flame retardant (OPFR) pollutants and biochars are commonly present and continually released into soils due to their increasingly wide applications. In this study, for the first time, the sorption of OPFRs on biochars was investigated. Although triphenyl phosphate (TPhP) and triphenylphosphine oxide (TPPO) have similar molecular structures and sizes, TPhP exhibited much faster and higher sorption than TPPO due to its stronger hydrophobicity, suggesting the dominant role of hydrophobic interactions in TPhP sorption. The π-π electron donor-acceptor (EDA) interactions also contributed to the sorption process, as suggested by the negative correlation between the sorption capacity of the aromatic OPFRs and the aromatic index (H/C atomic ratios) of biochar. Density functional theory calculations further showed that one benzene ring of aromatic OPFRs has no electrons, which may interact with biochar via π-π EDA interactions. The electrostatic attraction between the protonated P = O in OPFRs and the negatively charged biochar was found to occur at pH below 7. This work provides insights into the sorption behaviors and mechanisms of aromatic OPFRs by biochars.

中文翻译：

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芳香族有机磷酸盐阻燃剂在热和水热生产的生物炭上的吸附

摘要

芳香族有机磷酸盐阻燃剂（OPFR）污染物和生物炭由于其用途越来越广泛而通常存在并不断释放到土壤中。在这项研究中，首次研究了OPFRs在生物炭上的吸附。尽管磷酸三苯酯（TPhP）和三苯膦氧化物（TPPO）具有相似的分子结构和尺寸，但由于其具有更强的疏水性，因此与TPPO相比，TPhP表现出更快，更高的吸附性，表明疏水相互作用在TPhP吸附中起主要作用。π-π电子给体-受体（EDA）相互作用也有助于吸附过程，这是由芳香族OPFRs的吸附能力与生物炭的芳香指数（H / C原子比）之间的负相关性暗示的。密度泛函理论计算进一步表明，芳香族OPFR的一个苯环没有电子，可以通过π-πEDA相互作用与生物炭相互作用。发现在低于7的pH值下，OPFRs中质子化的P = O与带负电荷的生物炭之间的静电吸引发生在这项工作中。这项工作提供了对生物炭对芳香族OPFRs的吸附行为和机理的了解。