Green photocatalyst Cu/NiO doped zirconia for the removal of environmental pollutants

Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synthesized using one pot hydrothermal method. In these synthesized photocatalysts Cu-NiO ratio were 1:1, 1:2, 2:1 while CuNiO to ZrO2 ratio was kept constant (1:4). It was observed that these prepared materials displayed strong photocatalytic properties for the reduction of 4-nitrophenol (NP) and degradation of methylene blue (MB) and methyl orange (MO) respectively. XRD pattern, BET surface area, SEM and EDX have determined the physical properties of these synthesized photocatalysts. The effect of initial dye concentration, photocatalyst dose, pH, and time on the efficiency of degradation were evaluated by selecting efficient catalyst for 4-nitrophenol (4-NP) reduction, methylene blue (MB) and methyl orange (MO) degradation respectively. It was found that the degradation efficiency of these pollutants decreased with increase in the solution's pH and the initial concentration of dye while it enhanced by increasing the catalyst dose and irradiation reaction time during photocatalysis. Almost complete reduction of 4-NP was accomplished while using 20 mg/L of 4-NP and 0.02 g of catalyst within 5 min using 25 Mm NaBH4 solution. The reduction of 4-NP to 4-AP using Cu/NiO-ZrO2 photocatalyst follows pseudo-first order kinetics having a rate constant 0.882 min(-1) with R-2 value of 0.9957. In reactions of MB (50 mg/L) and MO (50 mg/L), approximately 99% degradation efficiency was achieved by using 0.03 g of catalyst dose with reaction time of 10 and 35 min, respectively.