4. Conclusions
The RHA prepared in this work could remove chromium
(III) ion from aqueous solution, but is not very efficient.
The rate of removal and removal at equilibrium could be
enhanced by decreasing the RHA dosage or by increasing the
initial chromium concentration or the adsorption temperature.
The removal was found to be unaffected by the pH and stroke
speed in the range of 2.5–5.4 and 30 as well 60 stroke/min,
respectively.
An empirical rate equation of chromium removal has been
determined.