Characterization of Fe0@Chitosan/Cellulose structure as effective green adsorbent for methyl Parathion, malachite Green, and levofloxacin Removal: Experimental and theoretical studies

Abstract

The green hybrid structure of zerovalent iron decorated chitosan/cellulose substrate (Fe0@CH/CF) was synthesized based on sugarcane bagasse. The synthesis procedures involved the isolation of cellulose by acid/alkaline washing followed by simple mixing of cellulose fractions with a chitosan solution. The formed chitosan/cellulose particles were decorated with zerovalent iron by the precipitation of iron from ferric chloride solution (3 M) using the green reducing extract of khaya senegalensis leaves. The product was studied as an adsorbent for levofloxacin, methyl parathion, and malachite green dye in batch adsorption tests. The Fe0@CH/CF achieved saturation adsorption quantities (103.08 mg/g (levofloxacin), 237.8 mg/g (methyl parathion), and 166.5 mg/g (malachite green)) higher than its components. The classic isotherm and kinetic properties of the uptake processes follow the assumptions of the Langmuir and pseudo-first order models, respectively. An advanced monolayer model with one energy was used to illustrate the equilibrium and adsorption mechanisms. Based on the steric parameters, the Fe0@CH/CF can adsorb two to three of levofloxacin (n = 2.92) and methyl parathion (n = 2.57) and up to four molecules of malachite green dye (n = 3.01) per site. The adsorbent shows high active adsorption site density for methyl parathion (107.6 mg/g) as compared to malachite green (64.7 mg/g) and levofloxacin (37.9 mg/g). The Gaussian (levofloxacin (5.9 kJ/mol), methyl parathion (7.4 kJ/mol), and malachite green dye (7.7 kJ/mol)) and adsorption energies (levofloxacin (10.1 kJ/mol), methyl parathion (18.2 kJ/mol), and malachite green dye (10.8 kJ/mol) demonstrate the physisorption mechanisms. The thermodynamic functions reflect the spontaneous and endothermic properties of the reactions.