State-of-the-art fabrication of crystalline zinc oxide for carbamate adsorption: Experimental, optimization, and molecular dynamics simulation

Abstract

The widespread use of hazardous chemicals in residential and agricultural activities has given rise to a significant global concern regarding pesticide pollution. Present research highlighted the adsorption of carbaryl (CBRL), a carbamate-type insecticide, using zinc oxide nanoparticles (ZnONPs) synthesized from Helianthus annuus flower petals. The study involved synthesizing ZnONPs through a sol-gel process using flower petal extracts, followed by characterization of the nanoparticles. The ZnONPs were then applied for adsorption of CBRL, with mechanisms explored through isotherms, kinetics, thermodynamics insights into CBRL-ZnONPs interactions. The Box–Behnken Design (BBD) of the Response Surface Methodology (RSM) was conducted to optimize the settings for CBRL removal during the batch method adsorption studies. Additionally, molecular dynamic simulation, and density functional theory (DFT) techniques provided deeper insights into the adsorption mechanism. The adsorption process is most precisely fitted linearly as Freundlich isotherm (R2 = 0.9934). By using the Langmuir isotherm, the adsorption demonstrated a noteworthy CBRL adsorption capacity of 158.34 mg/g. The kinetic analysis indicated that the process followed the pseudo-second-order model (R2 = 0.9978). The thermodynamic parameters suggested an endothermic (ΔHo = 36.279 kJ/mol), entropy-driven, and non-spontaneous adsorption process. Nevertheless, the RSM optimisation reveals that 99.983% of the CBRL was removed. Furthermore, throughout the process of adsorbent stability via regeneration, ethanol appears to be the most effective eluting agent, exhibiting the 58.33% desorption efficiency. The DFT analyzes combined visual and energetic insight into the molecular dynamics of the CBRL-ZnONPs system, revealed complex interactions and higher binding energies in complex-I. With the support of nanoparticle-based adsorbent, this research presents an in-depth overview of the adsorption of CBRL by ZnONPs, and important insights for creating efficient pollution mitigation strategies.