RSM-CCD Modeling and Optimization for Adsorptive Removal of Rose Bengal Dye from Aqueous Medium using CeO2 Nanoflowers

Objective: The focus of the study was to synthesize cerium oxide (CeO2) nanoparticles (NPs) and use them as nano adsorbents to remove toxic Rose Bengal (RB) dye from wastewater. Methods: A simple chemical method was used to synthesize CeO2 nanostructures. The nanostructures were characterized using XRD spectra, FESEM, and UV-Vis spectroscopy. The nanoparticles are used as nano adsorbents for wastewater treatment. Here, we utilized response surface methodology-central composite design (RSM-CCD) to optimize the batch adsorption studies rather than using the usual one-variable-at-a-time approach. The parameters for our investigations were the agitation period, CeO2 NP dosage, solution pH, and initial RB dye concentration. Findings: The characterization study showed that nanoflowers of a mean particle size of 44 nm and band gap of 3.68 eV were formed. RSM-CCD methodology for optimization resulted in an agitation time of 29.36 min, an NP dose of 0.302 g/L, a solution pH of 6.96, and a starting dye concentration of 88.65 mg/L gives the highest adsorption of 88.46%. The kinetics data indicated a strong fit with the pseudo-second-order (PSO) equation, while the Freundlich isotherm model fitted the equilibrium data accurately, resulting in 187 mg/g. The thermodynamic analysis suggested that adsorption was characterized by being endothermic, spontaneous, and physical. Novelty: The unique nanoflowers were employed and removal efficiency was predicted using a 2nd-order polynomial equation in Stat-Ease Design Expert Software ver.13. The model showed an excellent match with an adjusted R2 value of 0.9736 and a projected R2 value of 0.9256.