This study focuses on the removal of phenol from aqueous media using Agouraï clay (Fes-Meknes-Morocco region) and Geulmima clay (Draa Tafilalet region). The characterization of the clay by Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), N2 adsorption (BET), Scanning Electron Microscopy (SEM), and Thermogravimetric and differential thermal analysis (DTA/GTA) indicates that it is mainly composed of quartz, kaolinite, and illite. The results showed that raw Clay Agourai (RCA) and raw Clay Geulmima (RCG) adsorbed phenol very quickly and reached equilibrium after 30 min. Thermodynamic parameters reveal the physical nature of the adsorption, the spontaneity, and the sequence of the process. However, the structure and structural characterization of the solid before and after phenol adsorption indicated that the mechanism of the reaction was electrostatic and that hydrogen bonding played an important role in RCG, while kinetic modeling showed the pseudo-second-order model dynamics. The physics-statistics modeling was employed for describing the isotherm adsorption for both systems. It was found that the monolayer model with two different energy sites best describes adsorption irrespective of the system. The model indicates that the receptor density of each clay direct influences the adsorption capacity, demonstrating that the composition of the clay is the main source of the difference. Thermodynamic simulations have shown that the adsorption of phenol is spontaneous and endothermic, irrespective of the system. In addition, thermodynamic simulations show that the RCG could be adsorbed even further since the equilibrium was not achieved for any thermodynamic variable. The strength of this study lies in the determination of the adsorption mechanism of phenol on clay materials and the optimum values of temperature and pH.

The production of cobalt oxide nanoparticles and their use in the adsorption of methylene blue (MB) from solution is described in the paper. The X-ray diffraction patterns show that the synthesized cobalt oxide nanoparticles have a crystalline cubic structure. The study of the adsorption of methylene blue onto the cobalt oxide nanoparticles involved determining the contact time and initial concentration of the adsorption of MB on the adsorbent. The kinetics of adsorption were analyzed using two kinetic models (pseudo-first order and pseudo-second order), and the pseudo-second-order model was found to be the most appropriate for describing the behavior of the adsorption. This study indicates that the MLTS (monolayer with the same number of molecules per site) model is the most suitable model for describing methylene blue/cobalt oxide systems, and the parameter values help to further understand the adsorption process with the steric parameters. Indicating that methylene blue is horizontally adsorbed onto the surface of the cobalt oxide, which is bonded to two different receptor sites. Regarding the temperature effect, it was found that the adsorption capacity increased, with the experimental value ranging from 313.7 to 405.3 mg g⁻¹, while the MLTS predicted 313.32 and 408.16 mg g⁻¹. From the thermodynamic functions, high entropy was found around 280 mg L⁻¹ concentration. For all concentrations and temperatures examined, the Gibbs free energy and enthalpy of adsorption were found to be negative and positive, respectively, suggesting that the system is spontaneous and endothermic. According to this study’s findings, methylene blue adsorption onto cobalt oxide nanoparticles happens via the creation of a monolayer, in which the same amount of molecules are adsorbed at two distinct locations. The findings shed light on the methylene blue adsorption process onto cobalt oxide nanoparticles, which have a variety of uses, including the remediation of wastewater.

Indigo is one of the most famous and important dyes and is found in different heritage materials such as carpets, textiles, artworks, manuscripts, etc. However, until now, scientists never understood its spectroscopic behavior in heritage materials. Indeed, some bands or peaks undergo important shifts and others sometimes disappear. Thus, our objectives consist of multi-technical fingerprinting of this very important dye and elucidating its spectroscopic behavior. To achieve our objectives, several calculation methods have been applied and the obtained results are compared to77 experimental data. The correlation between the spectroscopic and structural properties revealed that: i) During the dyeing process, the Indigo molecule would undergo trans-cis photoisomerization thereby causing the rupture of the two intramolecular hydrogen bonds, followed by a dimerization process occurring through the establishment of two new intermolecular hydrogen bonds connecting the two monomers. ii) In heritage materials, the absence of indigo fluorescence is due most probably to the quenching phenomenon. iii) In the Raman spectrum, the shift in C = C vibration values (theoretical and experimental) is likely due to intermolecular interactions.

Indigo is one of the most famous and important dyes and is found in different heritage materials such as carpets, painting, manuscripts, etc. However, its spectroscopic behavior in heritage materials hasn’t been fully understood until now. Thus, our objectives consist of multi-technical fingerprinting of indigo and elucidating its spectroscopic behavior. To achieve our objectives, several calculation methods were applied and the obtained results are compared to experimental data. The correlation between the spectroscopic and structural properties revealed that: i) Indigo molecule would undergo trans-cis photoisomerization thereby causing the rupture of the two intramolecular hydrogen bonds, followed by a dimerization process occurring through the establishment of two new intermolecular hydrogen bonds connecting the two monomers; ii) the weakness of indigo fluorescence is due probably to the intermolecular hydrogen bonding interaction; iii) in the Raman spectrum, the shift in C = C vibration theoretical and experimental values is likely due to intermolecular interactions.