Novel chitosan–clay–iron nanocomposites supported on anodic aluminum as an efficient plate-shaped adsorbent for the removal of arsenic and dye from aqueous solutions

Abstract

Design and synthesis of plate-shaped adsorbents supported on anodized aluminum as a substrate were successfully carried out for the adsorption of methyl orange (MO) and arsenic [As(V)] ions in aqueous solutions. Chitosan, clay, and iron was also used on the anodized aluminum as a substrate to make a nanocomposite adsorbent. The specific properties of the prepared samples were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) analysis to determine the textural structure of the nanocomposites. The FESEM results showed that the formation of pores over the anodic surface was strongly related to anodizing time. Aluminum oxide and iron (hematite) phases were detected by XRD, which showed that the composite adsorbents were well synthesized. Isotherm adsorption was conducted using two models, of which the Langmuir model was in good agreement with the experimental results. The calculated maximum adsorption capacities based on the Langmuir equation for the adsorption of MO and As(V) ions were 53.48 and 14.70 mg/g, respectively. Pseudo first- and second-order models were used to demonstrate the adsorption mechanism of the anionic pollutants over the supported nanocomposites. The kinetic results indicated that the linearized pseudo second-order equation conformed best with the experimental data. The adsorption capacity was measured in six consecutive cycles to demonstrate the performance of the anodic adsorbent for removal of contaminants. The results illustrated 10 % and 15 % reductions in adsorption capacity of the anodized nanocomposite following six repeated cycles for MO and As(V) adsorption, respectively.