Wang Wei, Li Xiaofeng, Yuan Shengliu, Sun Jian, Zheng Shaokui
School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
Chemosphere. 2016 Oct;160:71-9. doi: 10.1016/j.chemosphere.2016.06.073. Epub 2016 Jun 28.
This study attempted to clarify the long-term pharmaceutical removal mechanism from sewage treatment plant effluent during the cyclical adsorption-regeneration operation of 5 commercial resin-based fixed-bed reactors with the simultaneous occurrence of electrostatic interactions and complex non-electrostatic interactions. It examined 12 pharmaceuticals belonging to 10 therapeutic classes with different predominant existing forms and hydrophobicities. Furthermore, the effect of the resin charged functional group (strong-base vs. strong-acid vs. non-ionic), porosity (macroporous vs. gel), and chemical matrix (polystyrenic vs. polyacrylic) on the mechanism was investigated to optimize resin properties and achieve higher pharmaceutical removal. The results reported herein indicate the importance of non-electrostatic interactions between pharmaceuticals and the resin backbone during short-term cyclical operation (i.e., the 1st adsorption-regeneration cycle). With the development of cyclical operation, however, non-electrostatic interaction-induced pharmaceutical removal generally decreased and even disappeared when equilibrium was achieved between the influent and the resin. Despite pharmaceutical therapeutic class or hydrophilicity, anion (or cation) exchange resin preferentially removed those pharmaceuticals that were predominantly present as organic anions (or cations) by ion exchange process during long-term cyclical operation (i.e., ≥6 adsorption-regeneration cycles). Besides pharmaceuticals predominantly present as undissociated molecules, some amphoteric pharmaceuticals containing large amounts of zwitterions were also difficult to remove by ion exchange resin. Additionally, neither resin porosity nor chemical matrix had any significant effect on the long-term pharmaceutical removal mechanism.
本研究试图阐明在5个基于商业树脂的固定床反应器的循环吸附-再生操作过程中，同时存在静电相互作用和复杂的非静电相互作用时，污水处理厂出水长期药物去除的机制。该研究考察了12种属于10个治疗类别的药物，它们具有不同的主要存在形式和疏水性。此外，研究了树脂带电官能团（强碱型与强酸型与非离子型）、孔隙率（大孔型与凝胶型）和化学基质（聚苯乙烯型与聚丙烯酸型）对该机制的影响，以优化树脂性能并实现更高的药物去除率。本文报道的结果表明，在短期循环操作（即第一个吸附-再生循环）中，药物与树脂主链之间的非静电相互作用很重要。然而，随着循环操作的进行，当进水与树脂之间达到平衡时，非静电相互作用引起的药物去除通常会降低甚至消失。在长期循环操作（即≥6个吸附-再生循环）中，无论药物的治疗类别或亲水性如何，阴离子（或阳离子）交换树脂通过离子交换过程优先去除那些主要以有机阴离子（或阳离子）形式存在的药物。除了主要以未解离分子形式存在的药物外，一些含有大量两性离子的两性药物也难以被离子交换树脂去除。此外，树脂孔隙率和化学基质对长期药物去除机制均无显著影响。
