Preparation and Characterisation of Activated Carbon from Agrowastes Peanut Seed (African Canarium) and Palm Kernel Shell

Abstract

Two agro wastes were selected and carbonized at 600^oC for 45min and 800^oC for 30min and each was portioned into three different parts. Each portion was activated with HCl, H₂SO₄ and H₃PO₄ as activating agents. The activated carbons were characterized for some important parameters such as pH, ash content, nitrogen, carbon content, sulphur, fat, fibre, protein, moisture content, carbohydrate, oxygen, hydrogen, sodium, potassium and pore volume. Wastewater from battery industry was collected and treated with the activated carbons with a view to determining the extent of the heavy metal adsorption ability. The results of the characterization shows pH of 6.31 for Peanut Seed activated carbon and 7.23 for Palm Kernel shell carbon, while the pore volume ranged from 3.8 X 10^-5 to 2.3 X 10^-5m³/g. The percentage yield of activated carbon before activation is 28.01% and 32.61 for Peanut Seed carbonized 800^oC and 600^oC respectively, while that for Palm kernel shell is 32.19% and 34.58% for that carbonized at 800^oC and 600^oC respectively. The FTIR result shows a surface reorganization of the activated carbon with a formation of new functional groups after chemical activation. The trend in the adsorption capacity of the activated carbons was PNAC > PKAC. The adsorption data generated fitted well into the Freundlich isotherm model since most values of the determination coefficient (R²) >0.500 indicating a heterogeneous adsorption of heavy metals from aqueous solution. It was observed also that those carbon activated with H₃PO₄ were better adsorbents in most of the activated carbons produced irrespective of the heavy metals, followed by those activated with HCl while those activated with H₂SO₄ were the least. The ANOVA indicates that there exist a positive significance relationship between the reliability factor (R²) and the Langmuir constants in almost all the activated carbon types produced. So also it was for Freundlich isotherm constants except few of them. There was a great effect of the chemical activation process on the pore development in virtually all the activated carbon types produced as shown by the pore volumes of the activated carbons indicated by both before and after activation. This study has shown that activated carbon produced from Peanut Seed and Palm kernel shell can confidently be used as adsorbents in place of the traditional activated carbons used in treating industrial waste especially from battery industries using HCL, H₂SO₄ and H₃PO₄ as activating agents.