RESUMEN
The purpose of this research was to learn more about the primary and secondary properties of Moroccan natural clay in an effort to better investigate innovative adsorbents and gain access to an ideal adsorption system. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) and X-ray fluorescence were employed for identification. SEM revealed clay grains, including tiny particles and unevenly shaped sticks. First- and second-order rate laws, representing two distinct kinetic models, were applied in the kinetic approach. Adsorption of dye MB onto natural clay was studied, and the results agreed with the 2 s order model. The significant correlation coefficients support the inference that the adsorption process was governed by the Langmuir model. Subsequent DFT analyses demonstrated that the methylene blue dye's HOMO and LUMO surfaces are dispersed across most of the dye's components, pointing to a strong interaction with the clay. To determine how the dye might be adsorbed onto the clay, we employed quantum descriptors to locate its most nucleophilic and electrophilic centers. Endothermic reactions are evident during the MB adsorption process on clay, as indicated by the positive values of ΔH0 and ΔS0 (70.49 kJ mol-1of RC and 84.19 kJ mol-1 of OC and 10.45 J mol-1 K-1 of RC and 12.68 mol-1 K-1 of OC, respectively). Additionally dye molecules on the adsorbent exhibit a higher order of distribution than in the solution, indicating that the adsorption process is spontaneous.
RESUMEN
In an attempt to examine novel adsorbents in accessing an ideal adsorption system, this study aimed to help understand the main and secondary characteristics of a Moroccan natural clay. X-ray fluorescence, infrared, and scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) were used for the identification. The findings demonstrate that this Clay is composed of a mixture of quartz, calcite, magnetite, and Rutile in very high proportions. SEM revealed the presence of clay grains in the presence of fine particles and irregularly contoured sticks. The results of semiquantitative detection by EDX also reveal the presence of certain mineral species (Si, Al, Mg, Fe, K, Cl, S, Ca, and Na). The exploited kinetic technique was achieved using two different kinetic models: first- and second-order rate laws. Commensurate to the obtained results, the 2-sec order model better described the adsorption of dye MB onto the natural clay. The results confirmed that the adsorption process followed the Langmuir model with the high coefficient correlation obtained which are very close to 1. In the sequel, DFT results revealed that the HOMO and LUMO surfaces of the methylene blue dye are mostly distributed on all dye parts, reflecting possible strong interactions with the clay. The quantum descriptors investigated in this study identify the most nucleophilic and electrophilic centers that can be used to suggest a suitable mechanism for the adsorption of the dye by the clay. The values of enthalpy ΔH0 and entropy ΔS0 of activation were -15.88 kJ mol-1 and -0.021 J mol-1 K-1, respectively, show that the nature of the adsorption process of MB on clay is exothermic and the order of distribution of the dye molecules on the adsorbent increases with respect to that of the solution so the negative values of ΔG0 (from -9. 62 to -8.99 kJ mol-1) indicate that the adsorption process is spontaneous.
RESUMEN
To eliminate lead (Pb) ions from metallic solutions, the cationic resin in solid form was utilized. The characterization of the adsorbent was performed using GTA/GTD, SEM spectroscopy, and EDX analysis. The results of these analyses provided insights into the structure and composition of the resin. The removal of Pb (II) ions was found to be highly dependent on various parameters. Firstly, the pH of the metal solution played a crucial role, as the adsorption capacity increased with the pH of the solution, at a maximum equal to (R = 84.78%), at a pH = 8.0. Additionally, the concentration of Pb (II) ions present in the solution influenced the adsorption technique's capacity, with higher concentrations leading to increased adsorption, analysis overhead of high concentration present (100 mg L-1) of the metal lead (II) study, a saturation corresponding a plateau to the resin polymeric saturation is 93.18 mg g-1. To determine the optimal mass of the resin adsorbent, a study was conducted to maximize the removal of Pb (II) ions, at the mass 1.0 g showed that the proportion of inorganic pollutants removed from Pb (II) is entirely qualitative (100%). Furthermore, the effect of temperature on the adsorption process was investigated. It was observed that the rate of the Pb (II) adsorption process decreased as the temperature increased. Kinetic studies were performed to gain further insights into the adsorption process. Pseudo-first-order and pseudo-second-order models, along with the intra-particle diffusion model, were utilized for this purpose. The results indicated that the adsorption process was fast, as evidenced by the findings from the pseudo-second-order study. The saturation technical process was studied, employing several different isothermal models, including Langmuir, Freundlich, and Temkin. Among these models, the Langmuir model was found to best describe the phenomenon of lead metal adsorption by the resin polymeric, is equal to 11.23 mg g-1, with the experimental value precisely (R2 = 0.999). Finally, various thermodynamic techniques were applied to analyze the adsorption process. The thermodynamic parameters such as ΔG° (- 9.78 to - 9.27 kJ mol-1), ΔH° (14.85 kJ mol-1), and ΔS° (0.017 kJ mol-1) were determined. These values indicated that the adsorption process was endothermic and spontaneous, further emphasizing its impetuous nature. The results of the molecular dynamics calculations demonstrated that amino groups are very important in defining the characteristics of cation adsorption. We conclude that this new adsorbent has the potential to significantly improve the process of regularly removing heavy metal ions from wastewater.
RESUMEN
In this work, we study the elimination of three bivalent metal ions (Cd2+, Cu2+, and Pb2+) by adsorption onto natural illitic clay (AM) collected from Marrakech region in Morocco. The characterization of the adsorbent was carried out by X-ray fluorescence, Fourier transform infrared spectroscopy and X-ray diffraction. The influence of physicochemical parameters on the clay adsorption capacity for ions Cd2+, Cu2+, and Pb2+, namely the adsorbent dose, the contact time, the initial pH imposed on the aqueous solution, the initial concentration of the metal solution and the temperature, was studied. The adsorption process is evaluated by different kinetic models such as the pseudo-first-order, pseudo-second-order, and Elovich. The adsorption mechanism was determined by the use of adsorption isotherms such as Langmuir, Freundlich, and Temkin models. Experiments have shown that heavy metals adsorption kinetics onto clay follows the same order, the pseudo-second order. The isotherms of adsorption of metal cations by AM clay are satisfactorily described by the Langmuir model and the maximum adsorption capacities obtained from the natural clay, using the Langmuir isotherm model equation, are 5.25, 13.41, and 15.90 mg/g, respectively for Cd(II), Cu(II), and Pb(II) ions. Adsorption of heavy metals on clay is a spontaneous and endothermic process characterized by a disorder of the medium. The values of ΔH are greater than 40 kJ/mol, which means that the interactions between clay and heavy metals are chemical in nature.
