Gd-doped ZnO:TiO2 heterogenous nanocomposites for advance oxidation process

Abstract Gd doped ZnO:TiO2 nanocomposites with doping concentration of Gd from 0, 0.25, 0.5, 0.75 and 1 at.% were synthesized via sol-gel method for advance oxidation process (AOP) and coded as GZT0, GZT1, GZT2, GZT3 and GZT4, respectively. The composite phases observed in the X-ray diffraction (XRD) pattern are attributed to the synergistic effects in AOP. The morphology of GZT0 to GZT4 was changed from nanorods to nanocauliflower covered with Gd3+ ions with increasing the doping concentration of Gd. The average crystallite size of samples was decreased from 17 to 11 nm with increasing the concentration of Gd. The optical bandgap was varied from 3.26 to 3.69 eV with the higher concentration of Gd. The advance oxidation process was investigated for the degradation of organic dyes as methyl blue (MB) and methyl orange (MO) under UV irradiation. The optimized sample GZT3 (loading dose 1 gm/L) showed highest degradation efficiency 93% and 94.4% for MB and MO dyes, respectively. The estimation of mineralization factors of both dyes were examined through biological oxygen demand (BOD) and chemical oxygen demand (COD) tests before and after AOP. The investigations based on Gd-doped metal oxide nanocomposites have shown very promising results for AOP under UV light.