Magdy, Y. Altaher, H. and El Qada, E., Applied Water Science, 2018.   

Abstract :

In this research, the removal of 2,4 dinitrophenol, 2 nitrophenol and 4 nitrophenol from aqueous solution using char ash from animal bones was investigated using batch technique. Three 2-parameter isotherms (Freundlich, Langmuir, and Temkin) were applied to analyze the experimental data. Both linear and nonlinear regression analyses were performed for these models to estimate the isotherm parameters. Three 3-parameter isotherms (Redlich-Peterson, Sips, Toth) were also tested. Moreover, the kinetic data were tested using pseudo-frst order, pseudo-second order, Elovich, Intraparticle difusion and Boyd methods. Langmuir adsorption isotherm provided the best ft for the experimental data indicating monolayer adsorption. The maximum adsorption capacity was 8.624, 7.55, 7.384 mg/g for 2 nitrophenol, 2,4 dinitrophenol, and 4 nitrophenol, respectively. The experimental data ftted well to pseudo-second order model suggested a chemical nature of the adsorption process. The R2 values for this model were 0.973 up to 0.999. This result with supported by the Temkin model indicating heat of adsorption to be greater than 10 kJ/mol. The rate controlling step was intraparticle difusion for 2 nitrophenol, and a combination of intraparticle difusion and flm difusion for the other two phenols. The pH and temperature of solution were found to have a considerable efect, and the temperature indicated the exothermic nature of the adsorption process. The highest adsorption capacity was obtained at pH 9 and 25 °C.