Malachite green adsorption by base-treated wood mill residues: Kinetics, isotherms, and thermodynamic studies,

The adsorption of malachite green (MG) was studied using chemically activated wood mill residues via a batch process. Maximum adsorption of 44.6 mg/g and 55.7 mg/g was obtained at optimum reaction time of 150 min and 180 min for the raw sample and the chemically treated sample, respectively. The kinetics analysis revealed that the adsorption process of MG by the raw sample is best described by a pseudo-first-order, whereas the pseudo-second-order model provided a better fit for the base-treated sample. The thermodynamic parameter of free energy confirmed the spontaneity and feasibility of the process, while positive enthalpy change (ΔH) values for both raw (17.2 kJ/mol) and treated samples (21.4 kJ/mol) affirmed that the adsorption process was endothermic. Desorption experiments demonstrated the potential for adsorbent regeneration and reusability, enhancing sustainability. Fourier transform infrared analysis confirmed that the base-modified wood residues effectively adsorbed MG dye, as evidenced by changes in key functional groups like O–H, N–H, C=C, and C-O. These findings contribute to the development of efficient adsorbents for environmental remediation, emphasizing the need for cost-effective and eco-friendly solutions.