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7678108 
Journal Article 
Removal of toxic Congo red dye from water employing low-cost coconut residual fiber 
Rani, KC; Naik, A; Chaurasiya, RS; Raghavarao, KSMS 
2017 
1 
Water Science and Technology
ISSN: 0273-1223
EISSN: 1996-9732 
IWA Publishing 
75 
9-10 
2225-2236 
English 
28498135 
WOS:000401150500024 
The coconut residual fiber (CRF) is the major byproduct obtained during production of virgin coconut oil. Its application as a biosorbent for adsorption of Congo red was investigated. The CRF was subjected to different pretreatments, namely, pressure cooking, hexane treatment, acid treatment and their combinations. The pretreatment of CRF with the combination of hexane, acid, and pressure cooking resulted in the highest degree of adsorption. The equilibrium data were analyzed and found to fit best to both Langmuir and Freundlich isotherms. Thermodynamic parameters such as standard free energy (ΔG0 kJ mol-1), standard enthalpy (ΔH0, kJ mol-1) and standard entropy (ΔS0, kJ mol-1 K-1) of the systems were calculated by using the Langmuir constant. The ΔG0, ΔH0 and ΔS0 were found to be 16.51 kJ mol-1, -19.39 kJ mol-1 and -0.12 kJ mol-1 K-1, respectively, at 300 K. These thermodynamic parameters suggest the present adsorption process to be non-spontaneous and exothermic. The adsorption process was observed to follow pseudo-second-order kinetics. The results suggest that CRF has potential to be a biosorbent for the removal of hazardous material (Congo red dye) with a maximum adsorption capacity of 128.94 mg g-1 at 300 K. 
Adsorption; Adsorption kinetics; Coconut residual fiber; Congo red; Thermodynamic; Wastewater treatment