Removal of synthetic dyes from aqueous media using biocomposites

Abstract

Wastewater which is produced from different textile industries is also the major cause of water pollution. In present research work, the optimum conditions of biosorption experiments for the elimination of synthetic dyes were determined by doing batch and continuous study. 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 optimum initial dye concentration was observed in 125-150 mg/L range to get maximum acid dyes elimination 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 potential of all biosorbents was investigated by temperature rise. It showed the exothermic nature of all biosorption processes that engaged in elimination of selected acid dyes. Langmuir and Freundlich biosorption equilibrium isotherms showed satisfactorily fitness on biosorption data where as the pseudo-first-order and pseudo-second-order both demonstrated satisfactory fitness on experimental kinetic data. Various thermodynamical parameters were determined to know about nature and feasibility of biosorption. Biosorption capability of selected efficient biosorbents for their respective acid dyes was reduced significantly by surfactants/detergents presence in acid dye solution. Maximum desorption was achieved using 0.5 N NaOH. In column study; 3 cm, 70 mg/L and 1.8 mL/min were observed as optimum bed height, inlet initial dye concentration and flow rate for attainment of highest 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 prepared biosorbents was done by FT-IR, thermal analysis and SEM which provided significant information about thermal stability, active binding functional groups and surface morphology.