Fuller's earth and fired clay as adsorbents for dyestuffs - Equilibrium and rate studies

The ability of Fuller's earth to adsorb a basic dye (Astrazone Blue - Basic Blue 69) and an acidic dye (Telon Blue - Acid Blue 25) has been studied. The equilibrium saturation adsorption capacities were 1200 mg dye g^-1 Fuller's earth and 220 mg dye g^-1 Fuller's earth for Astrazone Blue and Telon Blue, respectively. The kinetics of the adsorption processes were studied in an agitated batch adsorber. The time to reach 90% equilibrium value was achieved in less than 1 h. The variables investigated were agitation, adsorbent mass, initial dye concentration and temperature. A limited number of studies were undertaken using a fired clay but significantly lower saturation capacities were obtained, namely, 7 mg dye g^-1 fired clay and 40 mg dye g^-1 fired clay for Telon Blue and Astrazone Blue, respectively.