Graft Gum Ghatti Caped Cu₂O Nanocomposite for Photocatalytic Degradation of Naphthol Blue Black Dye

Photodecolorization of naphthol blue black dye through the use of Cu₂O nanoparticles capped with a biopolymer matrix containing gum ghatti (Gg) grafted with acrylic acid (AA) and acrylamide (AAm) (Cu₂O/Gg–AAm–AA) has been studied. While the homogeneous co-precipitation method was adopted for the synthesis of the Cu₂O nanoparticle, its incorporation into the biopolymer matrix (Gg–AAm–AA) was performed through the graft copolymerization method. The synthesized Cu₂O and Cu₂O/Gg–AAm–AA were characterized using SEM, TEM, XRD, EDX and UV–Vis spectroscopies, and BET surface area analysis. The photodecolorization experiment was performed using simulated ultraviolet and visible light irradiations, and these results compared with that of adsorption studies. The influence of pH, catalyst dose and dye concentration on the decolorization efficiency were also taken into consideration. The results revealed the Cu₂O/Gg–AAm–AA to be an excellent photocatalyst for effective elimination of naphthol blue black dye from water. The process was observed to be pH dependent, with pH 6 being the optimum value. The photodecolorization process increased with increasing catalyst concentration but decreased beyond the optimum value of 0.3 g L⁻¹. The process also decreased with increasing dye concentration. The result of the recyclability study indicates that the Cu₂O/Gg–AAm–AA nanocomposite can be effectively recycled and re-used over a number cycles.