3.3. Preparation of granular activated carbons
3.3.1. Acid-treated coconut shell carbon
For phosphoric acid activation, the previously described
method of Amuda and Ibrahim [13] with slight modification
was employed. The pulverized coconut shell was washed with
deionized water until leachable impurities due to acid and adherent
powered were removed. The sample was then treated with
50 wt.% phosphoric acid in an incubator at 110 ◦C for 24 h. It
was later soaked with deionized water until the solution pH was
stable. Then, the adsorbent was soaked in 27%, NaHCO3 (w/v)
till any residual acid left was removed as evident by the lack of
lead phosphate precipitate upon introduction of a few drops of
lead nitrate to sample of the wash water. The acid-treated coconut
shell carbon (ACSC) was then dried overnight in an oven (Mettler,
England) at 110 ◦C, cooled at room temperature and stored
in desiccators until use. A yield of 38% was determined for the
coconut shell carbons.