Abstract

In order to study the chemical compositions and surface properties of longan seed (Daw) activated charcoal, the influences of a phosphoric acid activation process was investigated before and after carbonization. Carbonization temperatures in this study were ranged from 400 - 800°C. It was found that higher carbonization temperatures resulted in a high amount of organic carbon and ashes, while the volatile matters were reversely lowered at higher carbonization temperatures. For carbonization temperatures studied between 400 - 800°C, the activated charcoal possessed a higher iodine number in comparison to the longan seed activated charcoal. Also, the longan seed activated charcoal, being activated by phosphoric acid prior to carbonization, had a greater iodine number than the one being activated by phosphoric acid and then undergoing carbonization. The highest iodine number was obtained from longan seed activated charcoal carbonized at 500°C. Surface properties of activated charcoal showed a loss of its side chains and inherent functionalities while being run through high carbonization temperatures, however, the P-O-C remained intact, especially under carbonization temperatures lower than 700°C. The surface images of the activated charcoal showed more rough.

Key words: Longan seed, carbonization, charcoal, activated charcoal, phosphoric acid.