Behaviour of aqueous sulfamethizole solution and temperature effects in cold plasma oxidation treatment

Alexander Sokolov,Marjatta Louhi-Kultanen

doi:10.1038/s41598-018-27061-5

Alexander Sokolov, Marjatta Louhi-Kultanen

Open Access

https://doi.org/10.1038/s41598-018-27061-5

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Abstract

The increase in volume and variety of pharmaceuticals found in natural water bodies has become an increasingly serious environmental problem. The implementation of cold plasma technology, specifically gas-phase pulsed corona discharge (PCD), for sulfamethizole abatement was studied in the present work. It was observed that sulfamethizole is easily oxidized by PCD. The flow rate and pH of the solution have no significant effect on the oxidation. Treatment at low pulse repetition frequency is preferable from the energy efficiency point of view but is more time-consuming. The maximum energy efficiency was around 120 g/kWh at half-life and around 50 g/kWh at the end of the treatment. Increasing the solution temperature from room temperature to 50 °C led to a significant reaction retardation of the process and decrease in energy efficiency. The pseudo-first order reaction rate constant (k1) grows with increase in pulse repetition frequency and does not depend on pH. By contrast, decreasing frequency leads to a reduction of the second order reaction rate constant (k2). At elevated temperature of 50 °C, the k1, k2 values decrease 2 and 2.9 times at 50 pps and 500 pps respectively. Lower temperature of 10 °C had no effect on oxidation efficiency compared with room temperature.

Highlights

Despite pharmaceuticals having first been detected in natural water bodies more than 40 years ago, these compounds were, until recently, not considered hazardous as their concentrations were very low
According to Van Boeckel[7], global consumption of antibiotics in the first decade of the 21st century increased by 36%
The reported values of a pseudo-first order reaction rate constant (0.015 min−1, 0.021 min−1 and 0.006 min−1) are lower than the results found

Summary

Introduction

Despite pharmaceuticals having first been detected in natural water bodies more than 40 years ago, these compounds were, until recently, not considered hazardous as their concentrations were very low. In Europe, total consumption of sulfonamides for human medicine was 121.5 tonnes of active pharmaceutical ingredient in 2012, which places the compound as the fifth most commonly used antimicrobial antibiotic. Sulfamethizole is a typical representative of the sulfonamides group It is quite popular in livestock farming, which poses problems as effluents from farms often go directly into water bodies bypassing wastewater treatment facilities[4,9]. The current work studies implementation of gas-phase pulsed corona discharge for the treatment of recalcitrant pharmaceuticals. This method allows the generation of short-living OH radicals and long-living ozone from water and oxygen. The generation of oxidants takes place in situ with low delivered energy, and with minimum production of heat in the working chamber of the PCD reactor

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Conclusion