Microwave-assisted removal of malachite green by carboxylate functionalized multi-walled carbon nanotubes: Kinetics and equilibrium study

Carboxylate group functionalized multi-walled carbon nanotubes (MWCNT-COOH) were synthesized by microwave-assisted method and characterized by Infrared spectroscopy; XRD methods and scanning electron microscope (SEM). These were used as adsorbent for the rapid removal of hazardous toxic dye Malachite green (MG) from aqueous phase. The impact of several effective parameters such as contact time, temperature, initial concentration, and agitation speed was investigated and the optimized values of influential parameters like pH, contact time, temperature, initial concentration, and agitation speed on experimentation were found to be 6, 50 min, 298 K, 15 mg/L and 150 rpm respectively. The experimental kinetic data were well fitted to the pseudo-first order reaction kinetics and results. Different adsorption isotherm models like Freundlich, Langmuir and Temkin are used to describe equilibrium adsorption in the adsorbent system and on experimentation the best agreement was achieved with the Langmuir model, for MG, the adsorption capacity of MWCNT-COOH surface was 49.45 mg/g at 298 K.