Adsorption performance of anionic textile dye (Nylosan Red N-2RBL) onto raw, sodic and fractionated sodic inorganic clay material

Abstract

The inorganic montmorillonitic clay material in raw and modified forms (sodic and fractionated, sodic materials) was evaluated as adsorbent for anionic textile dye (Nylosan Red N-2RBL). A various characterization using XRD, XRF, AFM, FTIR, TG, adsorption of methylene blue and pHPCN of the considered samples was realized. The experimental results show that, the adsorption was pH dependent with a high adsorption capacity of NR dye in acidic range. The pseudo-second-order kinetic model provided the best fit to the experimental data for the adsorption of dye by clay materials. The equilibrium adsorption data were analyzed by Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. The best fit of experimental data was obtained by the Dubinin–Radushkevich isotherm model. The maximum adsorption capacity of the raw clay calculated by the latest isotherm model is 62.05 mg/g. It is increased in modified forms (170.11 and 201 mg/g for sodic clay and fractionated sodified clay materials, respectively). Increasing solution ionic strength (NaCl, KCl, NaNO3, and Na2SO4) increased significantly the adsorption of dye.