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

This study aims to use green ZnO-ED NPs produced from Eleocharis dulcis (E. dulcis) extract to maximize solar photocatalytic degradation of raw textile wastewater. The optimization of photocatalysis was decided using the response surface methodology (RSM) as a function of ZnO-ED NPs mass load (0.1–2 g), initial concentration (10–100%), pH (4–9), and contact time (60–200 min). 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 ZnO-ED NPs granules before SPD. EDX analysis revealed the presence of impurities like copper (Cu). XRD analysis indicated the purity of ZnO-ED NPs after SPD, as the values were all quite similar to the XRD values before SPD. The results of an AFM analysis presented that agglomerations of ZnO-ED NPs, in contrast, were somewhat homogeneous in size, nature, and dispersion before SPD.