The adsorption of rhodamine-B and acid violet by coir pith carbon was carri
ed out by varying the parameters such as agitation time, dye concentration,
adsorbent dose and pH. The adsorption followed both Langmuir and Freundlic
h isotherms. The adsorption capacity was found to be 2.56 mg and 8.06 mg dy
e per g of the adsorbent for rhodamine-B and acid violet, respectively. Ads
orption of dyes followed first order rate kinetics. Acidic pH was favorable
for the adsorption of acid violet and alkaline pH was favorable to rhodami
ne-B. Desorption studies showed that alkaline pH was favorable fur the deso
rption of acid violet and acidic pH was favorable for the desorption of rho
damine-B. (C) 2001 Elsevier Science Ltd. All rights reserved.