Optimization and modeling of solar photocatalytic degradation of raw textile wastewater dyes using green ZnO-ED NPs by RSM

Abstract

This study aims to optimize solar photocatalysis for textile wastewater using ZnO-ED NPs produced from Eleocharis dulcis (E. dulcis) by RSM. The maximum decolorization (87.34%) and COD removal (100%) were recorded at pH 7, time (60 min), ZnO-ED NPs dosage (2 g/L), and 10% of color concentrations with R2 coefficient of 0.78 at P < 0.05. FESEM analysis showed the presence of granules with smaller diameters than the diameter of the granules before SPD. EDX analysis revealed the presence of impurities like copper (Cu). XRD analysis indicated the purity of ZnO-ED NPs after SPD. The results of an AFM analysis presented that agglomerations of ZnO-ED NPs were somewhat homogeneous in size, nature, and dispersion. According to the FTIR study, OH, CH, C=O, C=C, and C-O-C appear to be the primary functional groups of ZnO NPs that contributed to SPD. ZnO-ED NPs’ increased surface roughness was seen in their Raman spectra. Aromatic intermediates were produced, like aromatic amines or phenolic compounds, and led to the complete conversion of CO2 and H2O. These results indicated that ZnO-ED NPs play an important role in raw textile wastewater treatment and the possibility of reusability of ZnO-ED NPs over four different cycles.