Characterization and pre-leaching effect on the peels of predominant cassava varieties in Uganda for production of activated carbon

Abstract

Activated Carbon (AC) remains a key material for both industrial and domestic applications. The aim of this work was to characterize the peels of predominant cassava varieties grown in Uganda for production of AC. The selected varieties were; NASE 1, NASE 3, NASE 14, NASE 19, NAROCAS 1, and NAROCAS 2 due to more guaranteed raw material availability and potential for sustainability for AC production. The peels were characterized through proximate and ultimate analysis, bulk density, water-binding capacity, and lignocellulosic composition. Pre-leaching was done using NaOH of 1–4% w/v concentrations on two representative peel varieties. The dry basis (db) values of ash content, volatile matter and fixed carbon percentages of the peel varieties ranged from 1.93 to 4.36%, 77.93–81.93% and 13.78–15.34%, respectively. The ash content values were below 5% and hence may not necessitate pre-leaching to remove any ash forming agents. The dry basis char yield from the peels at 400 ​°C is in the range of 27.76–31.09%, qualifying them for AC production. The lignin, cellulose and hemicellulose compositions are in the ranges 9.0–16.0%, 5.5–15.0%, and 41.0–65.0%, respectively. The varieties with higher cellulosic content may be more suitable for highly porous AC production. Pre-leaching showed no remarkable reduction in the ash content but increased the volatile matte and char yield at low NaOH concentrations. Predominant Ugandan cassava peel varieties have potential for production of AC with alkaline pretreatment required in applications where high char yields are required.

Keywords

• Cassava peel
• Activated carbon
• Ugandan cassava varieties
• Ultimate analysis
• Pre-leaching