Removal of direct dyes from aqueous solution using various adsorbents

Dyestuff production units and dyeing units have always had a pressing need for techniques that allow economical pre-treatment for colour in the effluent. The effectiveness of adsorption for dye removal from wastewaters has made it an ideal alternative to other expensive treatment options. Removal of direct dyes [direct yellow 50 (DY50), direct red 80 (DR80) and direct blue 71(DB71)] from an aqueous solution by different adsorbents such as activated carbon, raw kaolinite and montmorillonite was investigated. The adsorption isotherm data were fitted to the Langmuir isotherm. Parameters of the Langmuir isotherm have been determined using the adsorption data. Adsorption capacity of RAC (commercial activated carbon), HAC (activated carbon obtained from shell of hazelnut), KC ( raw kaolinite) and MC (montmorillonite) increased in the following order: DY50 > DR80 > DB71, DB71>DR80>DY50, DR80>DB71>DY50 and DB71>DR80 (DY50 showed no absorption) for the direct dyes, respectively.