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چکیده
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Untreated wastewater discharged from textile units carries toxic dyes making it a carcinogenic and mutagenic hazard. Unlike traditional remediation techniques, biogenic zinc oxide nanoparticles (ZnONPs) are emerging as a promising alternative due to the unique physical properties and surface chemistry of nano-photocatalysts. Hence, in the current study we report the photocatalytic potential of biogenic ZnONPs immobilized on calcium alginate (Ca–Alg) beads to degrade methylene blue (MB) dye and treat textile effluents. The ZnONPs were synthesized by using the Bacillus cereus strain SZT1. The material characterizing techniques confirmed the production of stabilized spherical-shaped nanocrystals of ZnONPs with particle size ranging from 22 to 46 nm. The different concentrations (0, 1.0, 1.5 and 2.0 mg/ml water) of Ca-Alg immobilized ZnONPs showed promising photocatalytic decolorization potential against varying levels (50, 100 and 150 mg/l water) of MB. Dye degradation assays indicated that maximum concentration (2 mg/ml) of immobilized ZnONPS decolorized 50, 100 and 150 mg/l of MB up to 96.83%, 93.20%, and 88.47%, respectively, after 5 h of sunlight exposure. The textile effluents treated with immobilized ZnONPS showed significant reduction in pH, turbidity, chemical oxygen demand (COD), electrical conductivity (EC) and total suspended solids (TSS) as compared to the non-treated samples after 5 h of solar irradiation. Overall, this work highlights the photocatalytic function of biogenic ZnONPs coated on Ca–Alg beads for the decolorization of MB and treatment of textile effluents that could become a robust and eco-friendly approach for large-scale treatment of textile effluents.
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