Effects of MnO2/In2O3 thin films on photocatalytic degradation 17 alpha-ethynylestradiol and methylene blue in water

Abstract

In recent years, there has been a growing concern about some substances in the aquatic environment such as methylene blue dye (MB) and 17α-ethynylestradiol (EE2) hormone, mainly from waste textile and pharmaceutical industries, respectively. This waste, which is not effectively treated, generates large amounts of contaminated effluents. Textile industries, which use dyes mainly in their dyeing and finishing processes, generate a lot of effluent contamination by dyes. The 17α-ethynylestradiol hormone which is used in different contraceptive pills and in hormone replacement therapy, is the main substance found in the aquatic environment because of its high resistance to biodegradation. It is known that conventional water treatment processes, which involve the steps of coagulation, flocculation and sedimentation among others, have been reported to be ineffective in the removal of dyes and hormones. The heterogeneous photocatalysis has attracted great interest from many research groups around the world due to its potential application as a pollutant degradation method. For this purpose, the present work evaluated the performance of MnO 2 /In 2 O 3 thin films in the degradation process of the blue methylene and 17α-ethynylestradiol in aqueous solutions. The degradation processes were monitored by UV-Vis spectroscopy and HPLC chromatography. From these analyzes, the concentration of the solutions was evaluated and it was possible to infer that the MnO 2 / In 2 O 3 thin films significantly promoted a degradation of 89% of 17α-ethynylestradiol, however, the degradation of the methylene blue was not efficient.

Gliding arc plasma treatment of levofloxacin using experimental design approach

“…Similar observations are reported by many studies on the photocatalytic degradation of organic pollutants including pharmaceutical compounds. [ 71,74–76 ] It can then be deduced that this process is less effective for concentration thresholds > 25 mg L −1 as in our experimental conditions. Consequently, when plasma treatment reduces the initial concentration of the pollutant to 25 mg L −1 , it could be followed by photocatalysis to complete the degradation of the pollutant.…”

“…Photocatalysis is one of the AOPs, which allows the degradation of a wide variety of organic pollutants at low concentrations. [71][72][73][74] Accordingly, the coupling plasma followed by photocatalysis processes is proposed. Thus, solutions of levofloxacin at different concentrations were treated by photocatalysis using 20 mg of Degussa TiO 2 -P25 as photocatalyst.…”

Urchin-like hollow SiO2@γ-MnO2 microparticles for the rapid degradation of organic dyes

“…In recent years, the research on g-MnO 2 for AOPs has stimulated an extensive interest in the eld of treatment of organic dyes in wastewater. [32][33][34][35][36] In addition, it is well known that materials with excellent performance depend not only on the crystalline structure and composition but also on the morphology; sometimes, even the inuence of morphology plays a key role in the physicochemical performance. 37,38 To date, MnO 2 microparticles with different morphology, including 0-D nanoparticles, 1-D nanowires, nanorods, nanotubes, 2-D nanosheets, as well as 3-D hierarchical nanostructures, have been successfully prepared.…”