Boosted adsorptive removal of eosin yellow dye from aqueous solution with C–ZnO nanoparticles: optimization of process parameters

Abstract

This study investigates the effectiveness of ultrasound-aided sorption using carbon–doped zinc oxide nanoparticles (C–ZnO NPs) for the removal of eosin yellow dye (EY) from wastewater. Raman spectroscopy was employed to confirm the successful carbon doping in the ZnO lattice, while field emission scanning electron microscopy (FESEM) was used to observe the morphology of the C–ZnO NPs, revealing uniform pseudo-spherical grains with diameters ranging from 20 to 35 nm. The impact of important parameters such as EY base concentration (50–200 mg/L), C–ZnO NPs dose (0.125–1.0 g/L), initial solution pH (2.0–10.0), and reaction time (1–30 minutes) on EY dye removal was investigated to assess the adsorptive potential of C–ZnO NPs. The highest sorption efficiency of 95.90 ± 0.96 % for EY dye was achieved within 20 minutes using C–ZnO NPs dose of 0.50 g/L, a solution pH of 4.0, and at an EY base concentration of 50 mg/L. The adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with a sorption capacity of 232.59 ± 1.36 mg/g. Sono-assisted adsorption outperformed with a performance of 98.96% ± 0.85% as compared with conventional methods like magnetic stirring and overhead stirring, which had a performance of 73.24% ± 1.90% and 78.06% ± 2.0% respectively. C–ZnO is found to be a cost-effective adsorbent due to its low production cost of 31.0 $/kg and high reusability. As a result, this work emphasizes the prospective use of C–ZnO NPs as adsorbent for EY removal from wastewater on account of high sorption efficiency, superior adsorptive performance over ZnO NPs, and its cost effectiveness.