Efficacy of the Reactive Oxygen Species Generated by Immobilized TiO₂in the Photocatalytic Degradation of Diclofenac

Abstract

We report on the photodegradation of diclofenac (DCF) by hydrothermal anatase nanocrystals either free or immobilized in porous silica matrix (TS) in connection to the type and amount of reactive oxygen species (ROS), in order to have deeper insight into their role in the photocatalysis and to provide an effective tool to implement the DCF mineralization. TiO2and TS exhibit a remarkable efficiency in the DCF abatement, supporting that the utilization of anatase nanoparticles with the highly reactive{001},{010}, and{101}exposed surfaces can be an effective way for enhancing the photooxidation even of the persistent pollutants. Furthermore, the hydrothermal TiO2, when immobilized in silica matrix, preserves its functional properties, combining high photoactivity with an easy technical use and recovery of the catalyst. The catalysts performances have been related to the presence of OH•,O21, andO2-•species by electron paramagnetic resonance spin-trap technique. The results demonstrated that the ROS concentration increases with the increase of photoactivity and indicated a significant involvement ofO21in the DCF degradation. The efficacy of TiO2when immobilized on a silica matrix was associated with the high ROS life time and with the presence of singlet oxygen, which contributes to the complete photomineralization of DCF.

A facile synthesis of bismuth oxychloride-graphene oxide composite for visible light photocatalysis of aqueous diclofenac sodium

“…The shifting of peak from 276 nm revealed the formation of intermediate products. Di Credico 30 observed the peaks for DCF at wavelength 210, 240, 289, and 324 nm which were due to production of carbazole compounds that were formed by loss of Cl atom from DCF parent molecule. Several studies have reported that intermediate molecule such as hydroxylated and mono-halogenated carbazole compounds are generated in photolysis process for DCF pollutant.…”

A Green Approach for Preparing High-Loaded Sepiolite/Polymer Biocomposites

“…The demand for environmental process and products made from renewable and sustainable nonpetroleum-based resources is progressively growing in our society [1,2]. Among renewable materials, natural rubber latex (NRL) is the main elastomeric material obtained from the sap of the Hevea Brasiliensis tree, used for specific applications in different industry sectors, also combined with other rubbers and thermoplastics [3].…”

Engineering Charge Transfer Characteristics in Hierarchical Cu2S QDs @ ZnO Nanoneedles with p–n Heterojunctions: Towards Highly Efficient and Recyclable Photocatalysts

“…Beyond that, heterojunctions, which can effectively capture the photo-generated charge carriers to improve the charge separation efficiency, decrease the surface reaction over potential, enhance apparent quantum efficiencies and provide active sites for surface redox reaction at two different reaction sites, are believed to be essential to achieving highly efficient photocatalytic performances [26,27,28,29,30,31,32,33,34,35,36,37]. Recently, semiconductor heterojunctions composed of ZnO and other metal sulfides or oxides have also been extensively studied, for example combining ZnO with Cu 2 O, CdS, SnO 2 , MoO 3, and TiO 2 semiconductor materials [1,2,32,33,38,39,40]. Aforementioned results demonstrate that the composites developed by coupling different semiconductor materials could exhibit collective and enhanced property by reciprocal transfer of electrons and holes from one semiconductor to the other under irradiation and, consequently, realizing a higher photocatalytic activity [41,42,43].…”