Degradation of clofibric acid in UV/chlorine disinfection process: kinetics, reactive species contribution and pathways.

Yuqing Tang,Li Feng,Xueting Shi,Yongze Liu,Liqiu Zhang

doi:10.1098/rsos.171372

Abstract

As a potential endocrine disruptor, clofibric acid (CA) was investigated in this study for its degradation kinetics and pathways in UV/chlorine process. The results showed that CA in both UV photolysis and UV/chlorine processes could be degraded via pseudo-first-order kinetics, while it almost could not be degraded in the dark chlorination process. The observed rate constant (kobs) in UV photolysis was 0.0078 min−1, and increased to 0.0107 min−1 combining with 0.1 mM chlorine. The kobs increased to 0.0447 min−1 with further increasing the chlorine dosage from 0.1 to 1.0 mM, and reached a plateau at higher dosage (greater than 1.0 mM). The higher kobs was obtained at acid solution rather than basic solution. Moreover, the calculated contributions of radical species to kobs indicated that the HO• contributed significantly to CA degradation in acidic conditions, while the reactive chlorine species and UV direct photolysis dominated in neutral and basic solution. The degradation of CA was slightly inhibited in the presence of (1 ∼ 50 mM), barely affected by the presence of Cl− (1 ∼ 200 mM) and greatly suppressed by humic acid (0 ∼ 5 mg l−1). Thirteen main degradation intermediates and three degradation pathways of CA were identified during UV/chlorine process.

Highlights

Pharmaceutical and personal care products (PPCPs) are becoming ubiquitous in the environment and have been frequently detected in wastewater, seawater, surface water and even drinking water2018 The Authors
The clofibric acid (CA) degradation in UV photolysis and UV/chlorine processes could be well fitted by pseudo-first-order kinetics
Compared with UV photolysis, the greatly enhanced degradation of CA in UV/chlorine process could primarily be attributed to the formation of reactive radicals

Summary

Introduction

Pharmaceutical and personal care products (PPCPs) are becoming ubiquitous in the environment and have been frequently detected in wastewater, seawater, surface water and even drinking water. As a representative cholesterol-lowering drug, clofibric acid (CA) is considered as a potential endocrine disruptor because it interferes with the synthesis of cholesterol [3]. CA is one of the most persistent PPCPs known, with an estimated environmental residence of 21 years [4]. CA has a high environmental persistence and becomes a most commonly detected drug at concentrations of 270–660 ng l−1 in the water environment [5,6,7]

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Results

Conclusion