pH dependence of the binding interactions between humic acids and bisphenol A - A thermodynamic perspective
pH dependence of the binding interactions between humic acids and bisphenol A - A thermodynamic perspective
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腐殖酸和双酚 A 之间的结合相互作用的 pH 依赖性 - 热力学视角
DOI：
10.1016/j.envpol.2019.113292
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发表时间：
2019-12-01
影响因子：
8.9
通讯作者：
Zhang, Wei
中科院分区：
文献类型：
--
作者：
Gan, Li-hong;Yan, Zi-run;Zhang, Wei
双酚A（BPA）的广泛应用导致了天然水环境中BPA残留的出现。水体中存在的溶解性有机物（DOM）能与BPA结合，从而影响BPA在水环境中的迁移转化。pH值是决定DOM和BPA之间相互作用的关键因素。然而，在不同pH条件下驱动结合过程的机制仍不清楚。在这项研究中，BPA和腐殖酸（HA），DOM的主要成分，在较宽的pH值范围内的3-12，通过整合荧光猝灭，动态光散射和微量热法之间的相互作用进行了研究。HA和BPA之间的结合相互作用的pH依赖性从热力学角度解释。结果表明，HA可以自发地与BPA相互作用，形成稳定的HA-BPA复合物。随着pH值的增加，结合作用由熵驱动转变为熵-焓共同驱动。在酸性条件下，疏水力主导结合作用。疏水力和氢键的协同作用促进了中性条件下的结合过程。在碱性条件下，除疏水力和氢键外，静电斥力也参与了结合过程，削弱了结合强度。因此，中性pH有利于HA与BPA结合，从而增强BPA在天然水体中的溶解。研究结果有助于更好地了解BPA在水环境中的pH依赖性分布。(C)2019爱思唯尔有限公司版权所有。
The wide application of bisphenol A (BPA) leads to the emergence of BPA residuals in natural water environments. Dissolved organic matter (DOM) existed in water can bind with BPA, hence influencing the migration and transformation of BPA in aquatic environments. pH is a crucial factor governing the binding interactions between DOM and BPA. However, the mechanisms driven the binding process under different pH conditions are still unclear. In this study, the interactions between BPA and humic acids (HA), a primary component of DOM, are investigated over a wide pH range of 3-12 by integrating fluorescence quenching, dynamic light scattering and microcalorimetry. pH dependence of the binding interactions between HA and BPA are interpreted from a thermodynamic perspective. The results indicate that HA can spontaneously interact with BPA to form a stable HA-BPA complex. With the increasing pH, the binding interactions change from entropy driven to entropy-enthalpy co-driven. Hydrophobic force dominate the binding interactions under acidic condition. The synergy of hydrophobic force and hydrogen bond promotes the binding process under neutral condition. Under alkaline conditions, electrostatic repulsion participates the binding process in addition to hydrophobic force and hydrogen bond, weakening the binding strength. Therefore, neutral pH is favorable for HA to bind with BPA, consequently enhancing the dissolution of BPA in natural water bodies. The results are beneficial to better understand the pH dependent distribution of BPA in aquatic environments. (C) 2019 Elsevier Ltd. All rights reserved.