New combined experimental and DFT studies for adsorption of sole Azo-dye or binary cationic dyes from aqueous solution.

Textile-toxic synthetic dyes, which possess complex aromatic structures, are emitted into wastewater from various branches. To address this issue, the adsorption process was applied as an attractive method for the removal of dye contaminants from water in this article. An unprecedented integrated experimental study has been carried out, accompanied by theoretical simulations at the DFT-B3LYP/6-31G (d,P) level of theory to investigate how single Maxilon Blue GRL (MxB) dye or and its mixture with MG (Malachite Green) dyes interact with the adsorbent and compare the obtained results with the data obtained through experimentation. The full geometry optimization revealed the physical adsorption of dyes on the Al2O3 surface. Non-linear optical properties (NLO) results emphasized that the complex MG-Al2O3-MxB is a highly promising material in photo-applications, and the adsorbed binary system is energetically more favorable compared to the adsorbed sole dye system. The experimental results for (MxB) dye adsorption onto γ-Al2O3 affirmed that the optimum conditions to get more than 98% uptake were at dye concentration 100 ppm, pH 10, adsorbent content 0.05 g, and equilibrium time only 20 min. The kinetic and isothermal studies revealed that the adsorption accepted with the pseudo-second-order and Freundlich isotherm model, respectively. The removal efficiency of the mixture of MxB and MG dyes was the highest but did not change clearly with increasing the % of any of them. The details of the interaction mechanisms of the sole and binary dyes were proven.

Integrated experimental and theoretical insights for Malachite Green Dye adsorption from wastewater using low cost adsorbent.

Water pollution is one of the problems that threaten humanity, and to confront it with only experimental procedures is not enough. It is necessary to integrate both practical methods and theoretical calculations to achieve decontamination with the most accurate interpretation. Hence, discussing the experimental mechanism study of Malachite Green (MG) dye adsorption with the help of the application of density functional theory (DFT) calculations is the main goal of this article. The experimental results affirmed that the preparation of γ-Al2O3 by precipitation method using (NH4)2CO3 improved the porosity, the surface capability, and the adsorbent capacities (qmax = 210 mg/g) at optimum condition compared with the previous studies. Kinetic and equilibrium studies showed that the adsorption follows the pseudo-second-order model and Freundlich isotherm model, respectively. Also, the calculated and observed thermodynamic parameters exerted positive values of ΔH° and ΔS°, which translates into an endothermic process with increasing disorder of the system. Theoretical calculations at DFT- B3LYP/6-31G (d,P) level of theory were calculated to show the selectivity of using the cationic form of MG in the experimental measurements to find the interaction mechanism. The electronic structure and intramolecular charge transfer of MG, its cationic form and the complex of MG-Al were investigated theoretically at the B3LYP/6-31 G (d,p) level of theory. The equilibrium geometries of MG, its cationic form and the complex of MG-Al were determined, and it was found that these geometries are non-planar. The EHOMO and ELUMO energies can be used to calculate the global properties; chemical hardness (η), softness (S) and electronegativity (χ). The calculated non-linear optical parameters (NLO) of the studied compounds, the electronic dipole moment (µ), first-order hyperpolarizability (ß), the hyper-Rayleigh scattering (ßHRS) and the depolarization ratio (DR), showed promising optical properties. Finally, the computational and the experimental results indicated that the adsorption efficiency of MG from wastewater was directly associated with the dye electrophilicity power.

Novel mesoporous MnO2/SnO2 nanomaterials synthesized by ultrasonic-assisted co-precipitation method and their application in the catalytic decomposition of hydrogen peroxide.

Novel mesoporous MnO2/SnO2 catalysts were successfully synthesized via traditional and ultrasonic co-precipitation methods. Moreover, their catalytic efficiencies were evaluated in decomposition of hydrogen peroxide (H2O2). Interestingly, it was found that the mixing of MnO2 with SnO2 catalyst led to a significant improvement in their catalytic efficiencies compared with single oxides catalysts. However, the influence of ultrasonic power and irradiation time on MnO2/SnO2 nanomaterials were compared to get optimum synthetic condition. Subsequently, the catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption analysis and high-resolution transmission electron microscopy (HR-TEM). Results represented that the effect of ultrasonic power and irradiation time on MnO2/SnO2 catalysts exerted a great influence on the BET surface area and average particle diameter. Furthermore, the results showed that the best catalytic efficiency was obtained for the mesoporous MnO2/SnO2 catalyst which is sonicated at power of 60% for 30 min as optimum conditions. Finally, the outcomes appeared that the catalysts synthesized by ultrasonic co-precipitation method were more efficient than those synthesized by traditional co-precipitation in catalyzing H2O2 decomposition.