Perlite incorporating γ-Fe2O3 and α-MnO2 nanomaterials: Preparation and evaluation of a new adsorbent for As(V) removal

Novel composite adsorbents for As(V) removal from aqueous solution were synthesized by successfully incorporating alpha-MnO2 nanorods and gamma-Fe2O3 nanoparticles onto ball-milled expanded perlite carrier material. The composite adsorbents were characterized using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Powder X-ray diffraction (XRD) and Brunauer-Elmet-Teller nitrogen adsorption (BET-N-2 adsorption). The BET surface area of ball-milled expanded perlite increased by 4.0 and 7.1 times after the incorporation of gamma-Fe2O3 and alpha-MnO2 nanomaterials. The adsorption capacity for As(V) was found to be highly pH dependent and the adsorption kinetics followed the pseudo-second-order kinetic model. The Langmuir isotherm was found to be the best model to describe the adsorption of As(V) on both composites and the adsorption capacity was 4.64 and 7.09 mg g(-1) for gamma-Fe2O3 and alpha-MnO2 containing adsorbents as compared to 0.0025 mg g(-1) for perlite alone, confirming that these composites retain the constituent nanomaterial properties while being macroscopic particles suitable for arsenic removal in water treatment technology. (C) 2011 Elsevier B.V. All rights reserved.