Influence of chitosan and magnetic iron nanoparticles on chromium adsorption behavior of natural clay: Adaptive neuro-fuzzy inference modeling.

In the current study, the influence of iron oxide nanoparticles and chitosan (CS) on the adsorption capacity of natural clay for chromium removal from aqueous media was explored. Clay-based adsorbents (clay, CS/Clay, Clay/Fe3O4, and CS/Clay/Fe3O4) were manufactured and their physicochemical properties were identified. The effects of operating factors on the adsorption efficiency were optimized. The results showed that the adsorption equilibrium data for the clay, CS/Clay, and Clay/Fe3O4 corresponds to the Langmuir model, while for the CS/Clay/Fe3O4 is consistent with the Freundlich model. The maximum adsorption capacity (qmax) of Cr(VI) using clay, CS/Clay, Clay/Fe3O4 and CS/Clay/Fe3O4 were 63.69 mg/g, 80.30 mg/g, 97.08 mg/g, and 117.64 mg/g, respectively. It was showed that the addition of chitosan and Fe3O4 magnetic nanoparticles to the clay increases its adsorption capacity. The values of ΔG° and ΔH° parameter for Cr adsorption using adsorbents were negative, indicating that the removal process is spontaneous and exothermic. The kinetic behavior obeyed the pseudo-second-order model. The chromium removal process using all the adsorbents had a two-step mechanism. The wastewater of a leather factory was effectively treated using clay based-adsorbents. Based on R2, MSE, SSE, and ARE values, good agreement was observed between the ANFIS model and experimental outcomes.