Adsorption of isonicotinic acid from aqueous solution using multi-walled carbon nanotubes/Fe3O4

Magnetization of multi-walled carbon nano-tubes (MWCNT) was carried out by co-precipitation of Fe+2 and Fe+3 salts. The magnetization was confirmed by FTIR, FE-SEM and EDS analysis. Batch adsorption experiments were carried out to study the effect of various parameters like contact time (0-150 min), adsorbent dosage (2-16 g.L-1 for MWCNT, and 0.8-8 g.L-1 for magnetic MWCNT), initial concentration (1.23-6.16 g.L-1), and temperature (278 K-333 K) to separate isonicotinic acid by MWCNT and magnetic MWCNT. The kinetic data of adsorption was fitted using pseudo first order, pseudo second order and intra-particle diffusion models. It was found that pseudo second order fitted the kinetic data in both the cases. The equilibrium data was fitted using Langmuir, Freundlich and Temkin isotherm model. The equilibrium data was best fitted by Freundlich isotherm model in both the cases. The maximum adsorption capacities as predicted from Freundlich isotherm model were found to be 0.498 g.g(-1) and 0.416 g.g(-1) for magnetic MWCNT and MWCNT, respectively. The regeneration of adsorbents was carried out with I M NaOH solution. It was observed from the regeneration study that magnetic MWCNT showed good reusability properties. (C) 2018 Elsevier B.V. All rights reserved.