Mn (II) Adsorption on Activated Carbon Derived from Amaro (Spondias pinnata) Seed Stone

Abstract

Amaro (Spondias pinnata) seed stone powder was activated using phosphoric acid and carbonized in a muffle furnace at three different temperatures, viz. 300, 400 and 500oC (PAC-300, PAC-400 and PAC-500) to produced Activated Carbons (ACs). Thus, obtained ACs are characterized using Boehm titration, iodine number and scanning electron microscopy (SEM). The observed results attributed that PACs contained irregular sized and shaped particles with well-developed pores, which mostly consisted of carboxyl and phenolic functional groups. Among the ACs, PAC-400 had a highest values of methylene blue number, iodine number and specific surface area, which were 181mg/g, 371.02 mg/g and 582 m2/g, respectively. For the 150 mg/L of methylene blue concentration the adsorption capacity of all the PACs was 100% and the adsorption isotherm followed Langmuir isotherm with Qmax of 256.41 mg/g. Within 2 hours at pH 5, PAC-400 removed as high as 94% of Mn(II) ion from 25 mg/L and up to 40% from 400 mg/L concentration of manganese from an aqueous solution. The adsorption kinetics described pseudo second order kinetics indicating chemisorption. All the results attributed that the phosphoric acid activated amaro seed stone can be used as efficient adsorbent to absorb manganese from an aqueous solution.