Abstract

The objective of present research work focuses on the utilization of lignocellulosic material like coir pith for the removal of dye. Coir pith is an inexpensive and ecofriendly biosorbent that is utilized for the removal of Coomassie Brilliant Blue (R-250) dye from waste streams by adsorption method. The adsorption experiments were preceded considering the dose of adsorbent, stay time, concentration of dye, pH_(pzc) point zero charge activity by pH drift method. Adsorption isotherms for monolayer and multilayered adsorption were applied and the values of constants like Langmuir (K_L), Freundlich (K_f), and Dubinin-Radushkevich (E_s) were estimated by applying standard graphical method to assess the adsorption capacity of coir pith raw (CPR) and its modified carbonized form (CPC). The most appropriate model for the equilibrium process of CPR-CBB(R-250) and CPC-CBB(R-250) were the Freundlich and D-R isotherm model. A complete thermodynamic evaluation was conducted by estimating the values of enthalpy (?H°), free energy (?G°), and entropy (?S°) of the system. The surface morphology of CPR and CPC was evaluated by Scanning Electron Microscopy (SEM) and Fourier transforms infrared (FTIR) techniques. The results showed that with the rise in temperature of the system the dye adsorption rate was also increased. Thermodynamic analysis revealed that the adsorption process was endothermic and spontaneous in nature. Kinetics of dye removal was also investigated and results revealed that CPR and CPC follows second order rate constant. The maximum removal capacity of CBB(R-250) with CPR was found to be 70% and of CPC is 99%.

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