Taguchi optimization for production of activated carbon from phosphoric acid impregnated agricultural waste by microwave heating for the removal of methylene blue

Abstract

In this research activated carbons (AC) from barley husk (BMWA), corn cob (CMWA), and Agave salmiana leaves (AMWA) were obtained by chemical activation with phosphoric acid for the removal of methylene blue (MB). Taguchi experimental design (L9) was applied to conduct the experiments at different levels by altering four operating parameters. The effects of control factors on the AC yield were studied by analysis of variance (ANOVA). Power microwave of 200 W (level 1), radiation time of 4 min (level 2), H3PO4 at 60% (level 2), and nitrogen flow rate of 200 cm3/min (level 3) were de optimal conditions. AC with yields of 72% for AMWA, 96% for CMWA, and 93% for BMWA were obtained. AC showed mesoporous structures, anionic surfaces charges, and significant removal efficiencies of MB as a result of the effects of the activation agent and microwaves. It is the first report of the use of AMWA to obtain AC, as well as the use of microwave to optimize this process using nitrogen flow.