Abstract:

Due to the well performance in oxidation, flocculation and disinfection, ferrate has raised increasing attention as a functional water treatment agent. H₂-receptor antagonists (HRAs) as recalcitrant pollutants have been widely detected in natural environment. In this study, the widely used HRAs in clinic, i.e., famotidine (FMTD), ranitidine (RNTD), roxatidine (RXTD), cimetidine (CMTD) and nizatidine (NZTD) were selected as the target compounds to investigate the degradation performance of HRAs. The experimental results indicated that K₂FeO₄ was prone to react with the HRAs with thioether and carboxyl in structure. Except for RXTD, HRAs showed high reactivity towards K₂FeO₄, which removal efficiency was up to 98.4% and followed second-order degradation kinetics. Due to the protonation of K₂FeO₄ and the variation of HRAs species, the second-order rate constants were highly dependent on pH. The water matrices, i.e., Cl^-、HCO${}_{\mathrm{3}}^{-}$ and humic acid (HA), would scavenge HRAs degradation and the scavenger effect was dependent on the concentration of water matrices. As the complexity of real water samples, the removal of HRAs by K₂FeO₄ was affected. However, the removal efficiency of RNTD in different water samples was up to 80% except for hospital wastewater, in which it was only 65%. After treated by K₂FeO₄, the toxicity of HRAs was reduced significantly.

Key words: potassium ferrate, H₂-receptor antagonist, degradation kinetics, real water, toxicity

摘要：

高铁酸盐［Fe(Ⅵ)］兼具氧化、絮凝和消毒等功能，是备受关注的一类多功能水处理剂。本文针对在自然水域中H₂受体拮抗剂类药品（HRAs）经常被检出并难以去除的问题，通过高铁酸钾（K₂FeO₄）对5种临床上常见HRAs［即法莫替丁（FMTD）、雷尼替丁（RNTD）、罗沙替丁（RXTD）、西咪替丁（CMTD）和尼扎替丁（NZTD）］进行氧化降解研究。结果表明，在pH=7条件下，K₂FeO₄更倾向与带有硫醚键结构和羧基结构的HRAs反应。HRAs（除RXTD外）对K₂FeO₄具有较高的反应活性，降解率高达98.4%，并且符合二级反应动力学特性。反应二级速率常数与pH有较高的相关性，其主要是由于K₂FeO₄质子化和HRAs形态受pH的影响。不同浓度的水体基质（Cl^-、HCO₃^-和腐殖酸）对K₂FeO₄氧化降解HRAs有不同程度的抑制作用。实际水体中复杂的水质特征影响K₂FeO₄对HRAs的去除，但除医疗废水外，K₂FeO₄对RNTD的去除率高达80%，医疗废水中的去除率为65%。经K₂FeO₄处理后，HRAs的生态毒性可显著降低。

关键词: 高铁酸钾, H₂受体拮抗剂, 降解动力学, 实际水体, 生态毒性