REMOVAL OF SYNTHETIC DYES FROM AQUEOUS MEDIA USING BIOCOMPOSITES

Abstract

Industrial colored wastewater plays an important role in environment pollution. In present study, the removal of synthetic acid dyes was carried out in batch and column mode with biocomposites using biosorption technology. The effect of different experimental parameters such as pH, biosorbent dose, initial dye concentration, contact time and temperature were determined to investigate the optimum conditions for attaining the maximum removal of acid dyes. The optimum pH for getting the maximum biosorption of four selected acid dyes (ADG-180, AO-RL, ANB N-RBL and ATB E-2G) was observed in acidic range (2-6) while the 0.05 g/50 mL biosorbent dose (PPy/SB, PAn/SB, PPy/Ch, PAn/Ch, PPy/St and PAn/St; PPy/RH, PAn/RH, PPy/Ch, PAn/Ch, PPy/St and PAn/St; PPy/PH, PAn/PH, PPy/Ch, PAn/Ch, PPy/St and PAn/St and PPy/CS, PAn/CS, PPy/Ch, PAn/Ch, PPy/St and PAn/St ) was determined as optimum dose for the removal of all four selected acid dyes respectively. The equilibrium was attained within 45-60 min for all selected biosorbents for the elimination of selected acid dyes. The initial dye concentration in the range of 125-150 mg/L was considered as optimum for getting the maximum elimination of acid dyes using different types of selected biosorbents. The optimum temperature for getting maximum removal of all selected acid dyes was observed as 30 ºC and reduction in biosorption capacity of all biosorbents was investigated with the rise of temperature. It showed the exothermic nature of all biosorption processes involved in the removal of selected acid dyes. Both Langmuir and Freundlich biosorption isotherms showed the satisfactorily fitness on equilibrium biosorption data where as the pseudo-first-order and pseudo-second-order both showed the satisfactory fitness on biosorption kinetic data. Different thermodynamic parameters were determined to understand the nature and feasibility of biosorption process. The significant effect of different concentrations of electrolytes and heavy metal ions on the biosorption potential of selected most efficient biosorbent for the removal of their respective acid dyes was observed. The biosorption efficiency of selected efficient biosorbent for respective acid dyes was reduced significantly in the presence of surfactants/detergents in dye solution. Maximum desorption was achieved using 0.5 N NaOH. In column study, optimum bed height, flow rate and inlet dye concentration were found to be 3 cm, 1.8 mL/min and 70 mg/L for the achievement of maximum biosorption of ADG-180, AO-RL, ANB N-RBL and 90 mg/L for ATB E-2G dye. The biosorption study of real textile effluents was also carried out for the application of this technology on practical scale. The characterization of biosorbents was carried out using thermal analysis, FT-IR and SEM which provided the information about thermal stability, active binding functional groups and surface morphology.