The impact of solvents on the efficiency of cationic dye adsorption from a solution onto protonated Faujasite-type zeolite (FAU-Y) was investigated in the prospect of supporting potential applications in wastewater treatment or in the preparation of building blocks for optical devices. The adsorption isotherms were experimentally determined for methylene blue (MB) and auramine O (AO) from single-component solutions in water and in ethanol. The limiting dye uptake (saturation capacity) was evaluated for each adsorption system, and it decreased in the order of MB–water > AO–water > AO–ethanol > MB–ethanol. The mutual distances and orientations of the adsorbed dye species, and their interactions with the oxygen sites of the FAU-Y framework, with the solvent molecules, and among themselves were inferred from Monte Carlo simulations and subsequently utilized to rationalize the observed differences in the saturation capacity. The dye–solvent competition and the propensity of the dyes to form compact pi-stacked dimers were shown to play an important role in establishing a non-uniform distribution of the adsorbed species throughout the porous space. The two effects appeared particularly strong in the case of the MB–water system. The necessity of including solvent effects in modeling studies is emphasized.

The increasing discharge of synthetic dyes into industrial wastewater necessitates sustainable and low-cost treatment strategies. This study valorizes orange seed powder (OSP), an abundant agro-food residue, as a novel biosorbent for Congo red (CR) removal through a combined experimental and molecular simulation approach. Raw OSP was prepared solely by drying and grinding, without chemical activation, emphasizing its practical applicability and environmental sustainability. Physicochemical characterization using FTIR, SEM, and EDX confirmed adsorption-induced structural and compositional changes. Batch experiments evaluated the effects of initial dye concentration, adsorbent dosage, pH, temperature, and contact time. Equilibrium data were well fitted by the Langmuir and Freundlich isotherm models (R² ≈ 0.99), with a maximum adsorption capacity of 258.39 mg g⁻¹ at 25 °C and pH 4, and a removal efficiency exceeding 99.55%. The adsorption kinetics followed a pseudo-second-order model, while intraparticle diffusion contributed to the rate-controlling mechanism, as indicated by the Weber–Morris model. OSP demonstrated excellent regeneration performance over five adsorption–desorption cycles, retaining more than 96% of its initial CR removal efficiency when regenerated with methanol. Grand Canonical Monte Carlo (GCMC) simulations revealed that adsorption is primarily driven by electrostatic interactions, hydrogen bonding, and π–π stacking interactions, in good agreement with the experimental findings. Overall, raw OSP represents an efficient, regenerable, and sustainable biosorbent, highlighting the originality of integrating experimental investigations with GCMC simulations for wastewater treatment applications.

New single crystal hybrid ionic material, ethylenediammonium tetraacetate diperchlorate tetrahydrate (EDTAH₂²⁺.2ClO₄⁻.4H₂O), was synthesized. Its structure was affined by XRD, illustrating P2/n monoclinic system with cell parameters a=11.705(2), b=5.592(11), c=14.250(3)Å, β=101.747(7)° and filling rate Z=2. The 3D-supramolecular network is maintained by weak interactions as confirmed by Hirshfeld surfaces analysis, showing a supramolecular layered-like structure. UV-Vis spectrum reveals that the material is transparent in the visible domain; FT-IR spectroscopy investigates the vibration modes that were correlated to the functional groups of the material. In addition, the hybrid material exhibits significant in vitro antioxidant activity, as demonstrated by the β-carotene bleaching assay, showing effective inhibition of lipid peroxidation compared to BHT. In addition, density functional theory (DFT) calculations provided insight into the electronic structure and showed good agreement with the experimental results, supporting the observed antioxidant behavior.

A novel organic–inorganic ionic crystal 2,4-diamino-6-phenyl-1,3,5-triaziniumperchlorate (C₉H₁₀N₅⁺·ClO₄⁻) was synthesized via the reaction of benzoguanamine with perchloric acid. Its structure was affined by single-crystal XRD and characterized by UV-Vis and FT-IR spectroscopies. It crystallizes in a monoclinic system, with P2₁/c space group and lattice parameters of a = 13.7975 (6), b = 5.0711 (2), c = 16.6471 (9) Å, and β = 91.869 (2) ° and a cell volume of V = 1164.15 (9) ų. Additionally, the 3D-supramolecular network illustrates a supramolecular layer-by-layer arrangement. The two-dimensional fingerprint plots and Hirshfeld surface analysis showed that H∙∙∙O/O∙∙∙H dominates the interactions, contributing with 33.4%. The UV-Vis spectrum revealed two strong absorption bands at 204 and 247nm, indicating π→π* and n→π* electronic transitions, respectively, which were corroborated by TD-DFT calculations. FT-IR spectroscopy confirmed key vibrational modes consistent with triazinium cations and perchlorate anions, demonstrating strong agreement with the affined structure. TGA/DTG demonstrated enhanced thermal stability until 290 °C compared to benzoguanamine, with a four-stage degradation profile, illustrating robust thermal resilience. Moreover, BSSE-corrected interaction-energy calculations revealed that the charge-assisted cation–anion N-H···O hydrogen bond is the main cohesive force in the crystal, with a strong stabilization energy of −248.8 kJ mol⁻¹, while π-associated contacts mainly contribute to layered supramolecular packing. C₉H₁₀N₅⁺·ClO₄⁻ exhibits enhanced NLO properties in comparison to urea, due to the cooperative effect of ionic hydrogen bonding and ordered π-stacking.