Removal of Arsenic by Adsorption using Activated Carbon Derived from Zea mays

Abstract

The toxic pollutant arsenic ions present in the soil and water induce severe environmental and health issues in the North East of India and most of the Asian countries. This demand exploring the adsorption of arsenic ions in an aqueous medium by using a low-cost and non-pollutant adsorbent that is activated carbon obtained from the Poaceae family species (Zea mays). Activated carbon with calcium oxide (CaO) has been synthesized by pyrolysis at 650 ºC in the inert atmosphere. The characterization of activated carbon was done using a powder X-ray diffractometer, Fourier scanning electronic microscope, energy dispersive X-ray analysis and an inductively coupled plasma-mass spectrometer. The adsorption mechanism and efficacy of activated carbon were explored under optimized parameters such as pH of 5, 1 mg/mL of activated carbon dosage and 10 ppm of As(III) ions concentration at ambient temperature. The adsorption capacity of the activated carbon from the non-linear Sips model was found to be 8.4 mg/g and the linear Langmuir model was 29.85 mg/g. The adsorption mechanism from the non-linear, linear kinetic studies and Web Morris intraparticle diffusion model suggested the adsorption of arsenic ions by mass transfer, a diffusion mechanism as well as pseudo-second-order kinetics. Based on the results of desorption experiments, it is possible that the adsorbent can be reused for adsorption process for two cycles.