keywords: Sorption isotherm, dye removal, sorption kinetics, adsorption factors
This study presents the sorption model for the removal of 1-naphthyl amine dye from waste water using orange peels as the adsorbent. The responses of the various experimental quantities such as contact time, adsorbent dosage, temperature and concentration were investigated. Results showed that as the adsorbent dosage was increased from 2 to 6 g the amount of dye adsorbed increased from 0.098 to 0.219 mg/g. Similarly, increase in the time interval from 20 to 100 min results in increase in the amount of dye removed from 0.110 to 0.215 mg/g. The effect of dye concentration on adsorption showed that maximum adsorption of 1.093 mg/g at 50 mg/l. For an increase in temperature from 30 to 700C showed that the amount of dye adsorbed increased from 0.13 to 0.144 mg/g. The equilibrium values were fitted into the Langmuir and the Freunlich adsorption isotherms. A separation factor of 0.478 was obtained from the Langmuir equation representing a favourable adsorption. The coefficient of determination for both isotherms (R2) were 0.788 and 0.970, respectively. Pseudo First order and Pseudo Second order kinetics were employed to analyze the experimental quantities in which the rate constants K1 and K2 were obtained as 0.029 and 0.119 g/mg/min, respectively. Thermodynamic parameters like enthalpy (∆H), entropy (∆S) free energy (∆G) were also accessed, which revealed that the process is endothermic.