Photocatalytic treatment of AO7 and real textile wastewater using green-synthesized ZnO nanoparticles: RSM and Taguchi approach

In this study, ZnO nanoparticles were synthesized via a green synthesis method using Diospyros kaki L. peel extract, and their photocatalytic performances for the removal of Acid Orange 7 (AO7) dye and real textile wastewater were investigated. The effects of pH, initial dye concentration, and catalyst dosage on AO7 removal were optimized using a Box–Behnken experimental design and Response Surface Methodology (RSM). Under the optimum conditions (pH 10, initial dye concentration of 10 ppm, and catalyst dosage of 0.13 g), 100% dye removal was achieved within 270 min. The photocatalytic treatment of real textile wastewater was optimized using a Taguchi experimental design, and a color removal efficiency of 98.1% was achieved under the optimum conditions (pH 7, constant wastewater volume of 50 mL, and catalyst dosage of 0.13 g). Additionally, radical scavenging experiments performed to elucidate the photocatalytic mechanism indicated that hydroxyl radicals (•OH) play a significant role in the photocatalytic degradation of AO7. The synthesized ZnO nanoparticles exhibited high photocatalytic stability, good reusability and acted as efficient photocatalysts even under low-energy UV light conditions. Overall, the green-synthesized ZnO nanoparticles demonstrated promising potential as an effective photocatalyst for the removal of dyes and color from real textile wastewater. This study comprehensively presents the green synthesis of ZnO nanoparticles using Diospyros kaki L. peel extract and evaluates their effectiveness in the photocatalytic degradation of Acid Orange 7 (AO7) dye and real textile wastewater. Experimental conditions were optimized using the Box–Behnken design and the Taguchi approach. The study’s novelty lies in the application of ZnO nanoparticles derived from Diospyros kaki peel for the photocatalytic degradation of AO7 and the decolorization of real textile wastewater. This approach highlights the effective integration of green nanotechnology with the valorization of biomass waste for environmental remediation. In this regard, the study offers a sustainable and eco-friendly photocatalytic treatment method, presenting a potential solution for decolorization in the textile industry.