Activated Carbon and Manganese Coated Activated Carbon Precursor to Dead Biomass in the Remediation of Arsenic Contaminated Water

The two different dead biomasses were employed to obtain the activated carbon samples viz., rice hulls (AC-R) or areca nut waste (AC-N). Further, the surfaces of these activated carbons were modified with manganese to obtain the manganese coated activated carbons (MCAC-R and MCAC-N).These solids were assessed for their possible implication in the remediation of the aquatic environment contaminated with arsenic. The surface morphology of these solids was discussed with the scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDX) analysis. Various parametric studies viz., the effect of sorptive pH, concentration, background electrolyte concentration and contact time were studied under the batch reactor operations. The increase in sorptive pH (i.e., 2.0 to 10.0) and concentration (i.e., 1.0 to 10.0 mg/L) caused a great decrease in the percent removal of As(III) and As(V). Equilibrium modelling studies suggested that the data is fitted well to the Freundlich and Langmuir adsorption isotherms. The simultaneous presence of background electrolytes concentration (i.e., maximum 1,000 times NaNO₃) could not significantly affect the uptake of these two ions which inferred that the sorption of As(III) and As(V) by these solids predominantly occurred through strong chemical forces and may ultimately form ‘inner-sphere’ complexes. The kinetic data was best fitted to the pseudo-first order kinetic model. Studies conferred that AC obtained from these agricultural by-products/wastes modified with manganese were found to be potential and promising solid materials in the attenuation of As(III) and As(V) from the aquatic environment.