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 (KL), Freundlich (Kf), and Dubinin-Radushkevich (Es) 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%.
Highlights
Water is one of the natural limited reservoirs that is utilized at every step of different industrial processes
The adsorption, effect of point zero charge, thermodynamic and rate order kinetics were examined by series of adsorption experiments considering the ideal quantity of coir pith raw (CPR) and CPC and stay time
The results showed that the percentage removal capacity of CBB (R-250) increased with the increase quantity of CPR and CPC
Summary
Water is one of the natural limited reservoirs that is utilized at every step of different industrial processes. The water from industries is full of colorful as well as colorless chemical additives. The expulsion of this type of polluted water acts as an added factor to environment pollution due to the acidic pH, colored pigments, de-foamers, bleaches, detergents, equalizers and many other additives. Dyes are made of conjugated molecules that give them their respective color. The color depends on the number of conjugated bonds. Decolorization involves breaking of the conjugated bonds. The discharge of dyes in open water streams is worrying for both toxicological and esthetical reasons (Pignon et al, 2003). The presence of the dyes even at a very low concentration is highly observable and undesirable. (Rangabhashiyam et al, 2014; Gautama et al, 2014)
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