Mechanistic study of iron oxide nanoparticles synthesized from sapota leaves extract for the removal of crystal violet from model industrial effluent: Experimental, simulation and RSM modelling

There are serious health and environmental hazards when toxic dyes from the textile industry are dumped into waterways. These dyes were not removed by conventional adsorbents. Therefore, the current study offers a novel method for creating environmentally friendly iron oxide nanoparticles using sapota leaves extract. The physical and chemical characteristics of iron oxide nanoparticles were analysed by utilizing a variety of instrumental techniques. Batch adsorption studies revealed the ideal conditions for eliminating Crystal Violet (C 25 H 30 N 3 Cl) dye. With a pH of 10, 0.5 g of nanoparticles, 60 min of reaction time, 30 mg/L of dye, and 303 K of reaction temperature. The environmentally friendly iron oxide nanoparticles demonstrated successful removal of 93.90 % of Crystal Violet (CV) dye in the aqueous solution and the computed equilibrium adsorption capacity value (Q e ) was 2.817 mg/g at optimal conditions. Isotherm studies showed that, the Langmuir isotherm model described the adsorption of crystal violet dye by environmentally benign iron oxide nanoparticles. Thermodynamic studies revealed that the adsorption process was exothermic and spontaneous. The adsorption of crystal violet dye onto environmentally friendly iron oxide nanoparticles was described by kinetic parameters that were determined to be a pseudo-second-order model (R 2 = 0.9996). The CV adsorption methods suggested surface complexation, cation π-π interaction, hydrogen bonding, electrostatic interaction, and physical adsorption through various internal and surface moieties. Additionally, Response Surface Methodology (RSM) was assessed, and it was shown that while higher temperatures will negatively affect % removal, the low temperature of 303 K is advantageous for % removal. The outcomes of the RSM model are consistent with the observations from the experiments. To analyze the associated adsorption mechanism, theoretically sophisticated models such as Monte Carlo (MC) simulation, fractional free volume (FFV), adsorption loading and isotherm were employed. • Iron oxide nanoparticles were synthesized using the sapota leaf extract. • Batch adsorption studies show effective removal of crystal violet from the aqueous solution. • Thermodynamic studies confirm the spontaneous and exothermic adsorption. • RSM, MC, and FFV model conclusions agree with the experimental results.