The EFB fibre was obtained from the Palm Oil Research Institute of Malaysia (PORIM).
The pre-treatment of the fibre was carried out following the procedure outlined by Garg
et al. (2004). Accordingly, one part of the dried fibre was mixed with one part of
concentrated sulphuric acid and heated in a muffle furnace at 150°C for 24 h. The
material was cooled, washed with distilled water five to six times and soaked in 1%
sodium bicarbonate solution overnight to remove residual acid. The treated fibre was
then dried in an oven at 105°C for 24 h before being used as adsorbent for the
experiment.
Nickel nitrate, Ni(N03h.6H20, was dissolved in distilled water to prepare the test
solutions of approximately 20 mgtl Ni concentration. The exact concentration of Ni in the
solutions was determined before each set of adsorption tests.