Liu Beibei, Gao Yue, Yue Qinyan, Guo Kangying, Gao Baoyu
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 26600, PR China.
Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 26600, PR China.
J Hazard Mater. 2023 Oct 5;459:132272. doi: 10.1016/j.jhazmat.2023.132272. Epub 2023 Aug 10.
The composite pollutants formed by aged polystyrene (APS) and natural organic matter are complex and harmful, which lead to the deterioration of water quality. In this work, the interaction mechanism between humic acid (HA) and APS was discussed by investigating the changes in their functional groups. Besides, a novel polyaluminum-titanium chloride composite coagulant (PATC) was prepared, and its binding behaviors with HA@APS under different pH conditions were analyzed from a microscopic perspective. It was found that at pH 4, π-π conjugation was the dominant interaction between HA and APS. And the main removal mechanism of HA@APS by PATC was surface complexation. With the increase of pH, π-π conjugation, n-π electron donor-acceptor interaction (EDA), and hydrogen bonding gradually dominated the interaction between APS and HA. At pH 7, PATC hydrolyzed to form various polynuclear Al-Ti species, which could meet the demand for different binding sites of HA@APS. Under alkaline conditions, HB and n-π EDA in HA@APS were weakened, while π-π conjugation held a dominant position again. At this time, the main coagulation mechanism of PATC changed from charge neutralization to sweeping action, accompanied by hydrogen bonding. ENVIRONMENTAL IMPLICATION: Microplastics (MPs) have attracted the public's attention due to their potential toxicity to humans. The combined pollution of aged microplastics and humic acid (HA) will bring great harm to aquatic environment. The development of novel composite coagulants is hopeful to efficiently remove MPs and their combined pollutants. Elucidating the interactions between HA and aged MPs is helpful to understand the transformation and fate of MPs in actual environments, and to reveal the removal mechanism of composite pollutants by coagulation. The findings presented here will provide theoretical guidance for addressing the challenges of coagulation technology in treating new pollutants in practice.
老化聚苯乙烯（APS）与天然有机物形成的复合污染物复杂且有害，会导致水质恶化。本研究通过考察腐殖酸（HA）和APS官能团的变化，探讨了二者之间的相互作用机制。此外，制备了一种新型聚铝钛复合絮凝剂（PATC），并从微观角度分析了其在不同pH条件下与HA@APS的结合行为。结果表明，在pH为4时，π-π共轭是HA与APS之间的主要相互作用。PATC对HA@APS的主要去除机制是表面络合。随着pH升高，π-π共轭、n-π电子给体-受体相互作用（EDA）和氢键逐渐在APS与HA的相互作用中占主导地位。在pH为7时，PATC水解形成多种多核Al-Ti物种，能够满足HA@APS不同结合位点的需求。在碱性条件下，HA@APS中的氢键和n-π EDA减弱，而π-π共轭再次占据主导地位。此时，PATC的主要混凝机制从电荷中和转变为卷扫作用，并伴有氢键作用。环境意义：微塑料（MPs）因其对人类的潜在毒性而受到公众关注。老化微塑料与腐殖酸（HA）的复合污染会给水生环境带来极大危害。新型复合絮凝剂的开发有望高效去除MPs及其复合污染物。阐明HA与老化MPs之间的相互作用有助于理解MPs在实际环境中的转化和归宿，揭示复合污染物的混凝去除机制。本文的研究结果将为解决混凝技术在实际处理新型污染物时面临的挑战提供理论指导。
