Synthesis of Fe3O4@chitosan@ZIF-8 towards removal of malachite green from aqueous solution: Theoretical and experimental studies.

Discharges of dyes-containing wastewater from industries have created global concern. Removal of these substances from aqueous solution is very important and essential. Magnetic chitosan coated with ZIF-8 was prepared successfully and used to eliminate cationic dye malachite green in various conditions. To find the effectiveness of ZIF-8 towards malachite green removal, their surface interaction was investigated using density functional theory (DFT) calculations for the first time which the results show physisorption of malachite green on ZIF-8. The characteristics of adsorbent synthesized were evaluated using XRD, FTIR, FE-SEM, TEM and TGA analysis. In addition, the influence of different parameters on malachite green removal was investigated. The results showed that pH = 7, 40 mg of adsorbent dosage, 10 mg/L initial concentration, 40 min contact time and temperature of 25 °C were obtained as an optimum values for Fe3O4@chitosan@ZIF-8. The equilibrium data were in good agreement with the Langmuir model having maximum capacity (qm) value of 3.282 mg/g. The experimental data revealed that the adsorption process obeyed to pseudo-second order kinetic model. It was concluded that Fe3O4@chitosan@ZIF-8 can be utilized as an efficient and effective adsorbent for removal of toxic malachite green dye from aqueous solution.