TiO2-reduced graphene oxide nanocomposites for the trace removal of diclofenac

Abstract

Solar photocatalysis using TiO 2-reduced graphene oxide (T-RGO) nanocomposite as catalyst is explored for the removal of the last traces of diclofenac (DCF) pollutant from water. T-RGO nanocomposites of different compositions were synthesised by a modified process involving solvothermal treatment of titanium isopropoxide and graphene oxide (GO) in isopropanol medium. The prepared catalysts have been characterised by powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, photoluminescence emission spectroscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and N 2 adsorption-desorption measurements. The degradation of DCF is highly facile under solar irradiation in the presence of T-RGO with more than 98% of the 25 mg/L DCF aqueous solution getting degraded in 60 min followed by complete mineralisation in 100 min. Relevant reaction parameters such as catalyst loading, RGO content in the composite, concentration of DCF and the influence of pH on the degradation of the pollutant were identified and optimised. Reaction intermediates were identified by using LC-MS technique. The degradation followed Langmuir-Hinshelwood mechanism and pseudo first order kinetics. The stability and reusability of the catalyst are established. The efficiency of the catalyst in various real water matrices has also been proved thereby affirming its potential for commercial applications.

Interfacial Engineering of a TiO2 Photoanode via Graphene Nanoribbons for Efficient Quantum-Dot-Sensitized Solar Cells and Photoelectrochemical Water Splitting

“…Notably, GNR-incorporated TiO 2 -based photoanodes show a similar FTIR pattern, except the broadening of the absorption band within the wavenumber range of 800–450 cm –1 (Figure a). This absorption band corresponds to the Ti–O–Ti bond vibration of TiO 2 . The broadening of this absorption band can be indexed to additional Ti–O–C bond vibration caused by the chemical interaction between TiO 2 and GNRs …”

“…This absorption band corresponds to the Ti−O−Ti bond vibration of TiO 2 . 47 The broadening of this absorption band can be indexed to additional Ti−O−C bond vibration caused by the chemical interaction between TiO 2 and GNRs. 46 Further, to validate the existence of Ti−O−C bond vibrations on incorporation of the GNRs into TiO 2 , Raman spectroscopy was conducted (Figure 5b).…”

Integration of heterogeneous photocatalysis and persulfate based oxidation using TiO2-reduced graphene oxide for water decontamination and disinfection

“…The enhanced photocatalytic activity of T-RGO (containing 5 weight% GO) compared to synthesised TiO 2 towards the degradation of DCF under sunlight was established in our previous work [ 14 ]. Factors such as better adsorption of the substrate, enhanced light absorption, excellent mobility of charge carriers, increased production of reactive radicals etc.…”

“…The specific surface area and pore size distribution were acquired from nitrogen sorption isotherms on a Micromeritics Tristar 3000 V6.07A surface area and porosity analyser. The synthesis procedure and detailed discussion on the characterization of T-RGO nanocomposite have been reported elsewhere [ 14 , 15 ].…”

“…In this regard two promising AOPs viz., heterogeneous photocatalysis and PS-based AOPs could be integrated with T-RGO as it would play the dual role of a photocatalyst and a PS activator. Besides, T-RGO was reported to be more stable, easily separable and efficiently recyclable [12,13,14]. The improved visible light absorption of T-RGO would enable the use of direct sunlight as a benevolent and cost effective light source for activation.…”