Removal of textile dyes from industrial effluents using burnt brick pieces: adsorption isotherms, kinetics and desorption

Textile dyes, namely Sumifix Blue Exf (Dye 1), Sumifix Rubine Exf (Dye 2) and Sumifix Yellow Exf (Dye 3), show their characteristic lambda(max) values at 605 nm, 545 nm and 415 nm, respectively. Gel electrophoresis of the three individual dyes investigated indicates that all of them are negatively charged. Among different adsorbents, brick clay shows the highest efficiency for the removal of dyes from aqueous solution. The optimum values of experimental parameters, namely treatment temperature, adsorbent dosage, shaking time, settling time and initial solution pH determined to be 200 degrees C, 4.0 g, 15.0 min, 15.0 min and pH < 10, respectively. The Langmuir model is the best-fitted one for the experimental adsorption data of the dyes leading to the highest removal ability under optimized conditions as 1667 mg kg(-1), 3333 mg kg(-1) and 2500 mg kg(-1) for Dye 1, Dye 2 and Dye 3, respectively. All three dyes follow pseudo-second-order kinetics for their adsorption describing initial rate of adsorption in the order, Dye 1 approximate to Dye 2 (10,000 mg kg(-1) min(-1)) > Dye 3 (3333 mg kg(-1) min(-1)), and further, real dye effluent containing each of the above dyes having calculated initial concentrations of 42 mg L-1 (Dye 1), 106 mg L-1 (Dye 2) and 39 mg L-1 (Dye 3), shows, 87%, 86% and 45% removal efficiencies at their lambda(max) values with the treatment of burnt brick clay particles under optimized conditions. Desorption of the dyes from the dye-adsorbed adsorbent indicates that desorption prefers basic conditions.