The adsorption of Congo red and vacuum pump oil by rice hull ash

Rice hull ash (RHA) of large surface area was obtained by acid wash and the n calcination at 600 degreesC for 4 h. The white ash was then mixed with ka olin and starch ro make pellet adsorbents with reasonable strength to be ut ilized in a packed column. Both ash and pellet samples showed good adsorpti on capacities toward the organic substances in wastewater. Furthermore, the surface nature of the white ash and pellet adsorbent could be modified thr ough either hydration or esterification reactions. Corresponding changes in silanol concentrations were successfully correlated to changes in adsorpti on capacity toward either Congo red or vacuum pump oil molecules. (C) 2001 Elsevier Science Ltd. Ail rights reserved.