Palm fibre supplied by the Palm Oil Research Institute of Malaysia (PORIM) was activated with sulphuric acid and heat,
for further use in the adsorption experiments, according to the simple method used by Garg et al. One part of air-dried
adsorbent was mixed with one part of concentrated sulphuric acid in a ceramic crucible and heated in a muffle furnace for
24 h at 150 ◦C. The furnacewas equipped with an extractor fan to catch acid vapours. The heated material was cooled and washed five to six times with distilled water followed by soaking in 1% sodium bicarbonate solution overnight to remove residual acid.