Abstract

Quality indices of activated carbons from cattle bone (CB), coconut-shell (CS) and wood carbon (WC) as influenced by mode of activation (heat and acid) were studied using the non-activated carbon samples as control. Preliminary investigation was carried out to determine optimum condition for carbonization and activations. The iodine values, ash, bulk densities, moisture, hardness and porosity analysis of the samples were evaluated using standard methods. Heat (H) activation was at 950°C for 3 h to produce heat activated bone carbon (HCB), and 850°C for 2¹/2 h for heat activated coconut-shell (HCS) and wood carbon (HWC) while concentrated phosphoric acid (1:4) carbon: acid (w/w) was at 600°C for 2 h to produce acid activated wood (AWC), acid activated coconut-shell (ACS) and acid activated bone (ACB) samples. The activation yield for the acid activation ranged from 40.40 to 46.21% while heat activation ranged from 36.30 to 41.10%. Iodine values for heat activated carbons ranged from 828.39 (HCB) to 995.38 (HWC) mg/g. That of acid activated carbons ranged from 834.94 (ACB) to 914.17 (AWC) mg/g as compared with 66.2 to 222.7 mg/g for non-activated carbons (controls). Hardness of heat activated carbons ranged from 88.5 to 93.5% while that of acid activated carbons ranged from 62.0 to 89.5%. Bulk densities ranged from 0.40 to 0.79 g/cm³. The moisture for heat activated carbons ranged from 4.7 (HCB) to 8.4% (HWC) while that of acid activated carbons ranged from 5.0 (ACB) to 9.4% (AWC). The volume activities for the activated carbon samples ranged from 228.7 (HCB) to 324.9 (HWC). The ash for bone carbons ranged from 80.6 to 85.9% while those of coconut shell and wood ranged from 1.1 to 3.5%. Thecarbons presented BET surface areas between 718 and 1018 m²/g, and micropores and mesopores with volumes between 0.004 and 0.776 cm³/g. This study indicated that efficient activated carbons could be obtained from local raw materials by controlled activation with acid or heat for home and industrial purposes.

Key words: Quality indices, optimum condition, carbonization, activation.

Abbreviation

ABBREVIATIONS: ACB, Acid activated bone carbon; ACS, acid activated coconut shell carbon; AWC, acid activated wood carbon; HCB, heat activated bone carbon; HCS, heat activated coconut shell carbon; HWC, heat activated wood carbon; CAC, commercial activated carbon.