Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Tiantong National Field Observation Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China.
Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Tiantong National Field Observation Station for Forest Ecosystem, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China; Institute of Eco-Chongming (IEC), No. 20 Cuiniao Road, ChenJiazhen, Shanghai, 202162, China.
Environ Pollut. 2019 Dec;255(Pt 2):113292. doi: 10.1016/j.envpol.2019.113292. Epub 2019 Sep 20.
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.
双酚 A（BPA）的广泛应用导致其在自然水环境中残留。水中存在的溶解有机物（DOM）可以与 BPA 结合，从而影响 BPA 在水生环境中的迁移和转化。pH 值是控制 DOM 和 BPA 之间结合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，通过荧光猝灭、动态光散射和微量热法，在 pH 值为 3-12 的较宽范围内研究了 BPA 与腐殖酸（HA）之间的相互作用，腐殖酸是 DOM 的主要成分之一。从热力学角度解释了 HA 与 BPA 之间结合相互作用随 pH 值的变化。结果表明，HA 可以自发地与 BPA 相互作用形成稳定的 HA-BPA 配合物。随着 pH 值的增加，结合相互作用从熵驱动变为熵-焓共同驱动。在酸性条件下，疏水作用力主导结合相互作用。在中性条件下，疏水作用力和氢键的协同作用促进了结合过程。在碱性条件下，除了疏水作用力和氢键外，静电排斥也参与了结合过程，从而削弱了结合强度。因此，中性 pH 值有利于 HA 与 BPA 结合，从而增强 BPA 在天然水体中的溶解。这些结果有助于更好地理解 BPA 在水生环境中随 pH 值的分布。
