Solar-driven photodegradation of synthetic dyes by ternary of titanium oxide-copper oxide-chitosan catalyst

Abstract

The ternary titanium oxide (TiO2), copper oxide (CuO), and chitosan (TiO2/CuO/Chitosan) photocatalyst (composites) for the photodegradation of synthetic methyl orange (MO) were developed by entrapping copper ions and nanosized TiO2 into chitosan thin films at room temperature. TiO2 Degussa P25 was incorporated with CuO and Chitosan (CS) solution using an ex-situ synthesis method before being immobilized onto glass plates via a dip-coating technique. This study is the first time approach for a combination of a composite comprising two metal oxides to suppress the electron-hole recombination, thus enhancing their catalytic and adsorptive properties. The morphology and surface interactions of the TiO2/CuO/Chitosan composite were determined using techniques such as XRD, FTIR, RAMAN, and SEM-EDX, respectively. The results show the anatase phase and homogenous spherical features of TiO2. The TiO2/CuO/Chitosan composites (0.5 gL-1) exhibited excellent activity for the photodegradation of MO under solar irradiation (λ > 400 nm) at different pH. The decolorization efficiency increased according to pH 9 < pH 7 < pH 6 < pH 3 with the highest degradation efficiency of 85.29% at 1 ppm MO solution, reaching two times greater than the pristine TiO2 nanoparticles (56.55%). Complete degradation of MO was attained at 240 min of solar irradiation with pH 3 using the optimum TiO2/CuO/Chitosan composites of 1:4:1 composition (5 cycles of dip coating) and the photodegradation rate constant is 0.0073 min−1. The physic-chemical study has established the structure, crystalline phase, surface contact, and stability of the catalyst. The photocatalytic improvement under visible irradiation is attributed to band-gap reduction and suspension of electron-hole recombination of the ternary catalyst system. The results of this study offer guidelines for the design of a new synthetic strategy.for the preparation of an efficient photocatalyst for the selective oxidation of synthetic azo dyes compounds.