keywords: Adsorption, thermodynamics, kinetic models, Congo Red dye, Luffa cylindrica
Adsorptive removal of Congo Red dye from aqueous solution with Luffa cylindrica fibers was investigated. The effects of various experimental parameters such as the contact time, solution pH, temperature, biosorbent dosage and particle sizes were studied. Modelling of the kinetics data showed that pseudo-second order kinetic model provided the best fit for the process and increasing the adsorbent dosage increased the uptake of Congo Red dye. An optimum pH and contact time of 7.0 and 180 min were respectively used for the adsorption process in this study. The spectra obtained from Fourier Infrared Spectroscopy (FTIR) used for characterization of the adsorbent (Luffa cylindrica) revealed basic cellulosic functional groups which are good sites for adsorption. The adsorption process is endothermic with change in enthalpy (∆H°) =13201.04 KJ/mol; change in entropy (∆S°) = 26.3032 J/K/mol and positive values of Gibb’s free energy for all temperatures used in the study. This study revealed that Luffa cylindrica cellulose could be used for removing Congo red dye from wastewater in an environmentally friendly way.