Study of the optimization and mechanism for the remediation process of Malachite green dye via hybrid-based Magnetite-date's stones: Study of the optimization and mechanism for the remediation process

Dates' stones, a natural, abundant biowaste in Saudi Arabia, was hybridized with magnetite nanoparticles to produce hybrid-based magnetite dates' stones nanoparticles (D-Fe₃O₄-NPS). The synthesized sorbent was utilized for remediation of dye pollutants. A set of techniques were used to characterize D-Fe₃O₄-NPS. Scanning electron microscopy (SEM) showed masses of spherical magnetite nanoparticles dispersed uniformly among the dates' stones bed. The average diameter of the nanoparticles was found to be 8 nm, while BET surface area was 44.174 m²/g. The adsorption capability of the synthesized D-Fe₃O₄-NPS towards the malachite green (MG) dye was evaluated via optimization factors, isotherm, and kinetics studies. The optimization factors investigated included pH, temperature, contact time, and sorbent mass. It was found that the extent of MG adsorption by D-Fe₃O₄-NPS increased with initial dye concentration, contact time, the dosage of the sorbent, and pH of solution while temperature effect was not pronounced. Overall, the sorption kinetics of MG was best described by the pseudo-second-order model. Finally, a mechanism for the adsorption behavior of (MG) was suggested to obtain a deeper understanding of the sorption procedure. The results showed that D-Fe₃O₄-NPS could be very promising as a low-cost sorbent, which easily hooks MG from an aqueous environment.