Adsorption of the dye Remazol Red 198 (RR198) by O-carboxymethylchitosan-N-lauryl/γ-Fe2O3 magnetic nanoparticles

Abstract

O-Carboxymethylchitosan-N-lauryl/γ-Fe2O3 magnetic nanoparticles (OCh-LM) were synthesized and characterized using FT-IR, TGA, SEM and VSM. The OCh-LM was essentially spherical in shape, with a mean particle size of 11.1 ± 3.4 nm and saturated magnetization of 18.4 emu/g. The nanoparticle was used to remove the anionic dye Remazol Red 198 (RR198) from aqueous solution by the batch system. The kinetic data and adsorption isotherm were best fitted by the pseudo-second order kinetic model, and the Langmuir–Freundlich isotherm, respectively. Thermodynamic parameters such as change in enthalpy, change in Gibbs free energy and change in entropy were estimated, and the results indicated that the adsorption process was spontaneous and endothermic. The maximum adsorption capacity, calculated through the Langmuir–Freundlich model at 25 °C, was 216 mg/g. Desorption of the dye and reuse of the adsorbent were performed in four cycles. These results show that OCh-LM can be potentially used as a magnetic adsorbent to remove RR198 and probably other anionic reactive dyes from aqueous solution for avoiding the secondary pollution. Keywords: Dye adsorption, Magnetic nanoparticle, Magnetic separation, O-Carboxymethylchitosan-N-lauryl/γ-Fe2O3, Remazol Red 198