Non-equilibrium atmospheric pressure plasma assisted degradation of the pharmaceutical drug valsartan: influence of catalyst and degradation environment.

A Raji,V Kandavelu,K Navaneetha Pandiyaraj,M C Ramkumar,R R Deshmukh,D Vasu

doi:10.1039/d0ra05608a

Abstract

This paper investigated the degradation of the pharmaceutical drug Valsartan (VS) using non-equilibrium atmospheric pressure plasma (NEAPP) with various operating conditions. The heterogeneous photocatalyst ZnO nanoparticles (NP's) were synthesized using a hydrothermal process. The morphology, chemical composition and structure of as-synthesized ZnO NPs were examined by Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Then, VS degradation was examined in three subsequent treatment conditions including plasma treatment alone, the combination of plasma with as-prepared ZnO NPs and various environments (air, oxygen and hydrogen peroxide) at fixed plasma operating potential and treatment time. The degradation efficiency of plasma-treated VS by various conditions was observed using UV-visible spectroscopy. Optical Emission Spectrometry (OES) was used to characterize the distribution and emission intensity of various reactive species (OH˙, N2-SPS and O) during the degradation processes which plays a vital role in the degradation of VS. The role of OH˙ and H2O2 during the degradation process was further examined by chemical dosimetry and spectroscopic techniques. Furthermore, pH, conductivity and TOC of the untreated and plasma-treated VS were also investigated. The results on the degradation of VS showed that plasma treatment combined with ZnO NP's has a significant effect on degradation of molecules of VS than degradation processes carried out by other experimental conditions due to the formation of higher concentrations of various reactive oxygen and nitrogen species during the degradation processes.

Highlights

For the past few decades, industrialization and increase in population has been adversely affecting the human health and environment
The morphology of synthesized ZnO NP's was observed by FESEM which exhibits that the morphology of ZnO NP's has crystalline structure comprising of aggregated spherical particles (Fig. 2a)
The non-equilibrium atmospheric pressure plasma (NEAPP) in an aqueous solution containing pharmaceutical drug VS with ZnO NP's showed higher degradation (%) compared with other treatment conditions such as plasma alone, air, O2 and H2O2 due to the formation of higher concentration of ROS con rmed by spectroscopic analysis

Summary

Introduction

For the past few decades, industrialization and increase in population has been adversely affecting the human health and environment. The WHO and other health organizations reported that population growth and pollution are the main causes for the increasing number of human diseases worldwide.[1] the pharmaceutical industry plays a signi cant role in developing medication for reducing the chronic diseases. The presence of pharmaceutical compounds in very few extent in the range of nanogram level, it can produce acute and chronic effects on human health and aquatic life.[9]. For these reasons, various attempts have been made to remove pharmaceuticals compounds from waste water. Conventional treatment method cannot completely degrade the pharmaceutical compounds[10,11] and it generates the secondary pollutants. Advanced Oxidation Process (AOP's) is one of the very active methods to overpower the limitation of conventional treatment methods.[12,13,14] In AOP, various reactive oxygen and nitrogen species (ROS and RNS) such as OHc, O, NO2À, NO3À, and H2O2 during the degradation process which powerfully attack the toxic organic pollutants and convert them into nontoxic substance such as CO2 and H2O.15,16 in many cases, instead of complete oxidation, it produce partial oxidation products and it again generate secondary pollutants to the environment

Methods

Results

Conclusion