Removal of three nitrophenols from aqueous solutions by adsorption onto char ash: equilibrium and kinetic modeling

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-first order, pseudo-second order, Elovich, Intraparticle diffusion and Boyd methods. Langmuir adsorption isotherm provided the best fit 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 fitted well to pseudo-second order model suggested a chemical nature of the adsorption process. The R 2 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 diffusion for 2 nitrophenol, and a combination of intraparticle diffusion and film diffusion for the other two phenols. The pH and temperature of solution were found to have a considerable effect, and the temperature indicated the exothermic nature of the adsorption process. The highest adsorption capacity was obtained at pH 9 and 25 °C.

Mechanistic understanding of the adsorption and thermodynamic aspects of cationic methylene blue dye onto cellulosic olive stones biomass from wastewater

“…The highest R 2 for the black olive stones with Dubinin-Radushkevich and Temkin were observed at 35 °C. These results indicate that varying the temperature results in changes in the mechanism of the adsorption of MB onto both types of olive stones 65 .…”

“…The calculated isotherm constants and equation parameters related to the adsorption MB onto the olive stones are presented in Table 2. Upon general observation, all the isotherm models for the two adsorbents show high R 2 values, which means that the adsorption of MB onto the green and black olive stones could follow all models 65 . However, the green olive stones obtained the highest R 2 value with the Temkin isotherm model, whereas the black olive stones showed the highest R 2 value with the Langmuir isotherm model.…”

“…This means that the adsorption of MB onto the green olive stones according to the Temkin's mechanism of adsorption could be physical and endothermic at the lowest and highest studied temperatures, while chemical and exothermic at 35 °C. Comparing the black olive stones to the green olive stones, they exhibited high positive values of B D at all studied temperatures, indicating the chemical and the exothermic adsorption process of MB 62,65 .…”

“…In addition, the heat of sorption constant (B) value for green olive stones is negative, which means that the adsorption of MB onto green www.nature.com/scientificreports/ olive stones is a physical endothermic process. On the other hand, the black olive stones obtained a high value for the Temkin's heat of sorption constant and provide a chemical exothermic adsorption process of MB 32,38,65 . The applicability of the adsorption of MB onto the green and black olive stones to Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models with varying temperatures (35 °C and 45 °C) was studied.…”

Effect of Salinity and PH on the Industrial Effluent Treatment by Activated Carbon: Modeling of the Kinetic Adsorption and Equilibrium Isotherms

“…Activated carbons are considered as the most effective organics adsorbents with high surface areas (Andriantsiferana et al, 2015;Mohamed et al, 2015;Mohamed et al, 2016aMohamed et al, , 2016b. The adsorption capacity of activated carbon for the liquid adsorption of phenolic compounds depends on the solution conditions such as temperature, pH, ionic strength; and the adsorbate concentration (Magdy et al, 2018). The goal of the present work was firstly to study the adsorption efficiency of S23 commercial activated carbon in the treatment of bio-industrial effluent, and secondly to increase our understanding of adsorption mechanism of the phenols onto activated carbon.…”