Mechanism and Isotherm Modeling of Effective Adsorption of Malachite Green as Endocrine Disruptive Dye using Acid Functionalized Maize Cob (AFMC)

Abstract Cationic Malachite green has been identified as a candidate of endocrine disruptive compound found in the environment. In this study, the mechanism and isotherm modeling of effective adsorption of cationic malachite green dye onto acid functionalized maize cob (AFMC) was investigated by batch technique. The operational parameters such as initial concentration (100–600 mg/L); contact time (10–120 mins) and pH (3–10) influenced the removal efficiency and quantity adsorbed. Maximum of 99.3% removal efficiency was obtained at optimum conditions. AFMC physicochemical properties (surface area 1329 m2/g and particle size 300µm<Ф<250µm) enhanced its efficiency. Based on R2 > 0.97 and consistently low values of SSE, X2, HYBRID and MSPD adsorption statistical error functions (ASEF), equilibrium data were best fitted to Freundlich isotherm. Kinetic data were best described by pseudo second-order model with consistent R2 > 0.98 and validated by ASEF. The mechanism of process was better described by intraparticle diffusion. Evidence of adsorption process was confirmed by change in morphology and surface chemistry determined by SEM and FTIR respectively. The performance of AFMC enlisted it as a sustainable and promising low-cost adsorbent from agro-residue for treatment of endocrine disruptive dye polluted water.