Fe(II)-activated persulfate oxidation to degrade iopamidol in water: parameters optimization and degradation paths

Zijun Dong,Mu Li,Chengchun Jiang,Feiyun Sun,Guanhan Chen,Bandna Bharti

doi:10.1038/s41598-020-78468-y

Zijun Dong, Mu Li + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-78468-y

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Abstract

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Herein, iopamidol (IPM), one typical compound of ICM, was found to be rapidly degraded by ferrous activated persulfate oxidation (Fe(II)/PS) as compared with PS or Fe(II) alone. With a persulfate concentration of 1 mmol L−1, n(Fe(II))/n(PS) of 1:10, and a pH of 3.0, 78% IPM was degraded within 60 min, with a degradation rate of 0.1266 min−1. It was demonstrated that IPM degradation and deiodination were favored by a high temperature, while affected positively by acidic and neutral conditions. Radical quenching experiments and Electron Paramagnetic Resonace (EPR) spectra showed that the combined effects of SO4−· and ·OH contributed dominantly to degrade IPM, while the ·OH played an essential role during the degradation reaction. Through the Discrete Fourier Transform quantum chemical calculation, the possible reaction pathways for the oxidation of IPM by ·OH are as follows: IPM-TP651-TP667-TP541-TP557, IPM-TP651-TP525-TP557, IPM-TP705-TP631-TP661, and IPM-TP705-TP735. The obtained results showed that IPM could be degraded effectively by Fe(II)/PS system, giving a promising technique for IPM removal from water.

Highlights

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts
ICM is non-toxic to human bodies, it is the source of total adsorbable organic iodine (AOI) in an aqueous environment that can act as a precursors to highly toxic iodinated disinfection by-products (I-DBPs)[2]
It was found that both Fe(VI) oxidation and UV/chlorine process had a relative high IPM degradation rate among these processes, which were limited by their higher cost and potential production of DBPs

Summary

Introduction

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Kong et al studied the degradation of IPM by using UV/chlorine, by comparing with UV or chlorine a lone[10], and they found that in contrast to chemical processes, biochemical methods have limited pollutants removal efficiency. It took over 20 days to achieve more than 95% of IPM degradation by using anaerobic p rocess[11]. It was found that both Fe(VI) oxidation and UV/chlorine process had a relative high IPM degradation rate among these processes, which were limited by their higher cost and potential production of DBPs. Interestingly, Scientific Reports | (2020) 10:21548. It is necessary to develop an economical technology that could degrade IPM under a neutral and mild conditions

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