E ISSN: 2583-049X
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International Journal of Advanced Multidisciplinary Research and Studies

Volume 2, Issue 4, 2022

The Photooxidation of Flavonols and Polyaromatics in Textile Industry Wastewater with La Doped ZnO Nanocomposites and the Evaluation of Acute Toxicity Assays with Microtox and Daphnia magna



Author(s): Rukiye Oztekin, Delia Teresa Sponza

Abstract:

In this study, lanthanum doped zinc oxide (La-ZnO) nanocomposites (NCs) was used for the photocatalytic oxidation of pollutant parameters [COD (chemical oxygen demand) components (CODtotal, CODdissolved, CODinert), flavonols, polyaromatic amines and color] from the effluent of textile industry wastewaters (TI ww) at different operational conditions such as, at increasing photooxidation times (5-15-30-60-80-100 min), at diferent La mass ratios (0.5wt%, 1wt%, 1.5wt%, 2wt%), at different La-ZnO NCs photocatalyst concentrations (1-5-15-30-45 mg/l), under different ultraviolet (UV) irradiations (10-30-50-100 W/l), at different pH ranges (4.0-6.0-8.0-10.0), respectively. The physicochemical properties of the La-ZnO NCs produced under laboratory conditions were researched using X-Ray Diffraction (XRD) analysis, scanning electron microscopy (SEM) analysis, Fourier Transform Infrared Spectroscopy (FTIR) analysis and UV-visible absorption spectra analysis, respectively. The results were compared with pure ZnO. The maximum CODtotal, CODinert, total flavonols, total aromatic amines (TAAs) and color photooxidation yields were 99%, 92%, 91%, 98% and 99% respectively, under the optimized conditions, at 30 mg/l La-ZnO NCs with a La mass ratio of 1.5 wt% under 50 W/l UV light, after 60 min photooxidation, at 25oC at a pH=8.0. The photooxidation yields of kaempferol (KPL), quercetin (QEN), patuledin (PTN), rhamnetin (RMN) and rhamnazin (RHAZ) from flavonols and 2-methoxy-5-methylaniline (MMA), 2,4-diaminoanisole (DAA); 4,40-diamino diphenyl ether (DDE), o-aminoazotoluene (OAAT), and 4-aminoazobenzol (AAB) from polyaromatic amines and their metabolites were > 82% via photodegradation. The pollutants in TI ww were effectively photodegraded with La-ZnO NCs. 94.44% maximum Microtox (with Aliivibrio fischeri or Vibrio fischeri) acute toxicity yield was found in La-ZnO NCs=10 mg/l after 150 min photooxidation at 60oC. 90% maximum Daphnia magna acute toxicity removal was obtained in La-ZnO NCs=10 mg/l after 150 min photooxidation at 60oC. La-ZnO NCs concentrations > 10 mg/l decreased the acute toxicity removals by hindering the photooxidation process. Finally, the toxicity originating from the La-ZnO NCs is not significant and the real acute toxicity throughout photooxidation was attributed to the TI ww, to their metabolites and to the photodegradation by-products.


Keywords: Daphnia magna and Microtox (with Aliivibrio fischeri or Vibrio fischeri) acute toxicity tests, Flavonols and polyaromatic amines, Lanthanum doped zinc oxide (La-ZnO) nanocomposites, Photooxidation, Textile industry wastewater, Ultraviolet (UV) light irradiation

Pages: 413-430

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