Sunlight assisted photocatalytic dye degradation using zinc and iron based mixed metal-oxides nanopowders

For the photocatalytic degradation of the organic dyes present in wastewater, the ternary composites of metal-oxides nanopowders of zinc-iron-calcium (Zn-Fe-Ca), zinc-iron-antimony (Zn-Fe-Sb), zinc-iron-titanium (Zn-Fe-Ti) and zinc-iron-cobalt (Zn-Fe-Co) were synthesized and characterized by different instruments. The average particle size of the Zn-Fe-Ca and Zn-Fe-Ti mixed-oxides nanopowders was 10 ± 5 nm and that of Zn-Fe-Sb nanopowder was 20 ± 10 nm. The flakes of Zn-Fe-Co nanopowder were 10 ± 5 nm thick and 100 nm to 300 nm long. All the mixed-oxides were utilized for photocatalytic degradation of acridine orange (AO) where Zn-Fe-Sb degraded the 98 % of acridine orange (AO), within 20 min, while the same level of degradation was attained by Zn-Fe-Ti and Zn-Fe-Ca mixed-oxides in 80 min and 90 min, respectively. The more efficient Zn-Fe-Sb photocatalyst was further utilized for the degradation of malachite green (MG), brilliant green (BG), methyl orange (MO) and congo red (CR). Zn-Fe-Sb was found to be fast and efficient photocatalyst for the degradation of AO and therefore, the effect of various parameters was studied in detail to optimize the reaction conditions. Moreover, the Zn-Fe-Sb mixed-oxides were used to photodegrade the AO dye in four different environmental water samples (sea, tap and sewage). Keeping in view the practical conditions, a tube-type and funnel-type filters were designed for dynamic purification process using Zn-Fe-Sb mixed-oxides as catalyst under sunlight. The synthesized nanomaterials have great potential to contribute in the wastewater treatment technologies.