The preparation of activated carbon from agroforestry waste for wastewater treatment

Abstract

The scope of this study was to produce activated carbon from local agroforestry wastes (marula fruit stones, jackalberry seeds, eembe seeds, efukwa shells and eembu seeds) and assess the efficiency of the produced carbons in removing dyes and metal ions from wastewater. Preparation of activated carbons from efukwa shells, marula fruit stones, jackalberry seeds, eembe seeds and eembu seeds are described in this study. The carbons were chemically activated by treatment with 50% phosphoric acid. The dyes tested in this study were methylene blue and methyl orange and the metal ions tested were lead and zinc. The carbons produced in this study were compared to commercially powdered activated carbon (PAC) and granular activated carbon (GAC). In case of Lead ion and Powdered Activated Carbon (PAC) produced, the removal efficiency for Eembe, Eembu and Jackalberry was 100%, so as for the commercial powdered activated carbon, 100%. In case of Lead ion and granular activated carbon (GAC) produced, the removal efficiency for Eembu and Marula was 100% and for the commercial granular activated carbon was also 100%. In case of Zinc ion and granular activated carbon (GAC) produced, the removal efficiency for Eembu was 91% and Eembe had zero removal and for the commercial granular activated carbon was 89%. In case of Zinc ion and powdered activated carbon (PAC) produced, the removal efficiency for Eembe, Eembu and Efukwa was around 60%, while the powdered activated carbon (PAC) produced from Jackalberry and Marula had zero removal and for the commercial powdered activated carbon (PAC) the removal was 90%. In case of methyl orange dye and powdered activated carbon (PAC) produced, the removal efficiency for Eembu, Marula and Efukwa was 84% and for the commercial powdered activated carbon was 92%. In case of methyl orange dye and granular activated carbon produced, the removal efficiency for Eembu and Marula was 78% and for the commercial granular activated carbon was 87.5%. In case of methylene blue dye and powdered activated carbon (PAC) produced, the removal efficiency for Jackalberry, 84.4%; Marula, 83% and Eembe was 81.3 % and for the commercial powdered activated carbon was 84.4%. In case of methylene blue dye and granular activated carbon (GAC) produced, the removal efficiency for Jackalberry, 83%; Eembu was 81.25% and for the commercial granular activated carbon was 92.2%. The effectiveness of the produced activated carbon in most of the cases is comparable and in some cases equivalent to that of the commercial carbons. Key words: Activated carbon (AC), powdered activated carbon (PAC), granular activated carbon (GAC), adsorption.