Abdelmottaleb Ben Lamine

This work describes the modeling and analysis of methylene blue molecule on different adsorbents, namely, nickel alginate/graphene oxide (NA/GO) aerogel, nickel alginate/activated carbon (NA/AC) aerogel, and Trichosanthes kirilowii maxim shell activated carbon (TKAC). A multilayer statistical physics model was used to calculate the energetic and steric parameters of the adsorption of methylene blue on these adsorbents. Based on the modeling investigation, it was concluded that the formation of multiple dye adsorbed layers on these adsorbents could be feasible where physical adsorption interactions could be involved. Adsorption capacities at saturation of these adsorbents ranged from 542.97 to 470.03 mg/g, 790.66 to 684.47 mg/g, and 401.11 to 1236.24 mg/g for NA-GO aerogel, NA-AC aerogel, and TKAC, respectively. This research contributes with new findings for the understanding of dye adsorption on novel materials, which can be used in water pollution control.

A synthesized MIL-101-NH₂ has been used as an adsorbent to analyze Congo red (CR), methyl orange (MO), and acid chrome blue K (AC) dye adsorption phenomena. This investigation, based on statistical physics treatment, applied the double layer model with two energies to understand dye adsorption on three samples, namely, MIL-101-NH₂-1, MIL-101-NH₂-2, and MIL-101-NH₂-3, at T = 298 K. Modeling results indicated that dye adsorption occurred via a mixed adsorption orientation for CR and MO dyes and a non-parallel orientation for AC dye on the MIL-101-NH₂ surface. Dye uptake quantities varied from 2534.4 to 3440 mg/g for CR dye, 240.4 to 490.8 mg/g for MO dye, and 277 to 293 mg/g for AC dye. Thus, the highest adsorption amount appeared in the case of CR dye. Interpretation of the calculated energies showed that adsorption of the dyes on MIL-101-NH₂ is a physisorption phenomenon, which could be controlled through energetic parameters obtained via numerical findings using the statistical double layer model. Moreover, the expression of the model is exploited to investigate the thermodynamic functions, such as internal energy.

The adsorption isotherms of Reactive Red 120 (RR-120) on Brazilian pine-fruit shell activated carbon, at six temperatures (298, 303, 308, 313, 318 and 323 K) and pH = 6, were determined and interpreted using a double layer model with one energy. A statistical physics treatment established the formulation of this model. Steric and energetic parameters related to the adsorption process, such as the number of adsorbed molecules per site, the receptor sites density and the concentration at half-saturation, have been considered. Thermodynamic potential functions such as entropy, internal energy and Gibbs free enthalpy are analyzed, and the choice of the models is based on assumptions in correlation with experimental conditions. By numerical fitting, the investigated parameters were deduced. The theoretical expressions provide a good understanding and interpretation of the adsorption isotherms at the microscopic level. We believe that our work contributes to new theoretical insights on the dye adsorption in order to know the physical nature of the adsorption process.