Kinetic and isotherm modeling of adsorption of dyes onto rice husk carbon

Rice husk carbon (RHC) has the ability to adsorb the dyestuff from aqueous solution. It may be
useful low cost adsorbent for the treatment of effluents, discharged from textile industries. The
effectiveness of RHC have been tested for the removal of colour from the wastewater samples
containing three dyes namely crystal violet, direct orange and magenta. Effect of various parameters
such as agitation time, pH, temperature, adsorbent dose and concentration have been investigated
in the present study. The adsorption of dyes have been best described by pseudo first order
mechanism and Freundlich adsorption isotherms. The rate constant of adsorption (Kad) have been
determined, which are found to be 6.8 x 10–3, 8 x 10–3 and 10 x 10–3 min–1 for crystal violet, direct orange
and magenta respectively. Similarly the Freundlich constants related to the adsorption capacity (Kf) are
found to be 0.74, 0.44 and 0.68 g l–1 and intensity of adsorption (n) are found to be 0.41, 0.73 and
0.33 mg g–1 for above dyes respectively.