Removal of Cationic Dye (Basic Green) Using Raw and Modified Eichhorniacrassipes: Adsorption Kinetics, Isotherms, Thermodynamics and Mechanism Studies

摘要

This study deals with the adsorption potential of raw and NaOH modified Eichhorniacrassipes (water hyacinth) for the removal of basic green dye from aqueous solution. Batch experiments were conducted to investigate the effect of influencing parameters, such as pH, adsorbent dose, initial dye concentration, temperature and contact time on dye removal. The adsorbent was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Maximum dye removal efficiency of 86.9 % and 91.9% were obtained for raw and NaOH modified adsorbents respectively for the removal of basic green dye with an adsorbent dosage of 3 g/L and 1.5 g/L, at initial dye concentration of 100 mg/L in an optimum time of 90 min at 40℃. Adsorption isotherm models including Langmuir, Freundlich and Temkin and adsorption kinetics models, namely Pseudo-first order. Pseudo-second order and Elovich were studied. The adsorption data well fitted with Langmuir and Freundlich isotherm for raw and modified adsorbents,respectively. Pseudo-second order kinetic model was identified as a suitable fit for both raw and modified adsorbents. The analysis of thermodynamic parameters (change in enthalpy,change in entropy and change in Gibb's free energy) indicated that the adsorption process is spontaneous and endothermic in nature.