Adsorption of As (V) ions from aqueous solution by carboxymethyl cellulose incorporated layered double hydroxide/reduced graphene oxide nanocomposites: Isotherm and kinetic studies

Abstract

Efficient nanocomposite adsorbents were synthesized based on carboxymethyl cellulose (CE) incorporated Fe–Al layered double hydroxide/reduced graphene oxide (FAH-rGO/CE) for the adsorption of Arsenate (As (V)) ions in wastewater. Synthesized products were characterized by XRD (X-ray diffraction), FESEM (Field Emission Scanning Electron Microscopy), HRTEM (High Resolution Transmission Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy) and N2 adsorption–desorption analysis. The incorporation of CE moieties on FAH-rGO composites evidently improved the active sites on boundary layer and As (V) removal capacity (98%) thereby enhancing the surface area of composites (156.24 m2g−1). Various parameters affecting the adsorption such as adsorbent dosages (0.01–0.1 g/L), contact time of adsorption (60–600 min) and effect of pH (2–11) were optimized using batch adsorption techniques. Adsorption isotherms were well fitted to the Langmuir isotherm model (correlation coefficient R2≥ 0.9991) to prove the monolayer adsorption of As (V) ions on the adsorbent surface. The maximum adsorption capacity (qmax) of FAH-rGO, FAH-rGO/CE-1 and FAH-rGO/CE-4 were found to be 115.39, 170.36 and 258.39 mg g−1, respectively. Adsorption kinetics was calculated by following the pseudo-second-order model with high correlation coefficient (R2≥ 0.9996) value. In addition, the effect of pH, FTIR and EDS analysis revealed that the possible mechanism between the As (V) and CE composites was the electrostatic interactions with -OH and -COOH groups. Furthermore, FAH-rGO/CE adsorbent exposed good reusability even after five consecutive cycles (from 96% to 88%) with high stability. Thus, synthesized FAH-rGO/CE composites could be potentially used as an efficient adsorbent for As (V) adsorption in wastewater.