Effect of indium (III) doping on Ag3PO4 catalyst stabilization and its visible light photocatalytic activity toward toxic dyes in water.

Indium(III)-doped Ag3PO4 (In-AgP) catalysts at different weight percentages were elaborated by co-precipitation and subjected to XRD, SEM, UV-vis DRS, and FTIR characterization. The prepared catalysts were of spherical morphology and their diameters depends on doping dosage. The whole materials crystallize in a centered cubic system with a slight dissimilation in the positions of the characteristic peaks as a function of indium dosage. The photocatalytic performance of the catalysts under visible light was investigated in the photocatalytic degradation of anionic dye (methyl orange (MO)) and cationic dye (auramine O (AO)) in moderate acid, neutral, and basic pH conditions. Results showed more selectivity to MO than AO. Furthermore, indium-doped samples are more active in the acidic medium than the pure Ag3PO4 (AgP), and 10%In-AgP catalyst presents the highest activity. The degradation efficiency reached 99 % in 60 min for MO and in 180 min for AO. In addition, a high recycling stability was achieved and the catalyst retains its degradation capacity above 99 % after five cycles.

Improvement of photocatalytic degradation of methyl orange by impregnation of natural clay with nickel: optimization using the Box-Behnken design (BBD).

In this research work, the photocatalytic degradation of methyl orange dye was studied on nickel oxide supported on a natural Moroccan clay (Ni/NC). These catalysts have been prepared by dry impregnation of a nickel nitrate solution with different weight percentages (5, 10, 20% NiO). Experimental responses were obtained by a Box-Behnken (BBD) experimental design by varying the catalyst mass, solution pH, and initial dye concentration at three levels (low, medium, and high). The prepared catalysts were characterized using powder X-ray diffraction (XRD) to assess crystallinity and structure, Fourier transform infrared spectroscopy (FTIR) to detect different functional groups, scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis to study the surface morphology, and the optical characteristics of the catalysts were studied using absorption and diffuse reflectance measurements in the UV-visible range. The photocatalytic activity of the catalysts was evaluated in aqueous solutions under UV irradiation. ANOVA (analysis of variance) test is employed to recognize the significant factors and their interactions and then give the model equation for the percent dye degradation. The optimal values of the studied factors were determined by numerical optimization, and the results showed that about 100% degradation of the methyl orange dye could be achieved under the following optimal conditions, which are pH = 4.38, catalyst concentration of 0.99 g/L, and initial dye concentration of 30.42 mg/L.

ZnO-Zn2TiO4 heterostructure for highly efficient photocatalytic degradation of pharmaceuticals.

In this study, ZnO-Zn2TiO4 (ZTM) material was prepared through a novel synthesis method based on a ultrasound-assisted polyol-mediated process followed by calcination at a different temperature. Physical features of the samples were studied by using various analysis techniques including XRD, FT-IR, SEM/EDX, pHPZC, and UV-Vis DRS. Subsequently, the materials were employed as catalysts for the photocatalytic degradation of clofibric acid as a model pharmaceutical contaminant. The photocatalytic performance was evaluated under different conditions of calcination temperature, catalyst dosage, starting concentration, and initial pH of clofibric acid solution. The finding results revealed that hexagonal-tetragonal phases of ZnO-Zn2TiO4 calcined at 600 °C (ZTM-600) with an average crystallite size of 97.8 Å exhibited the best degradation efficiency (99%). The primary bands characteristic of ZnO and Zn2TiO4 were displayed by FT-IR analysis and the UV-visible DRS confirms the larger absorption capacity in UV-visible regions. The photogenerated electrons are the powerful reactive species involved in clofibric acid photodegradation process. This study shows a promising photocatalyst and provides new sight to rational design the facets of photocatalysis process for enhanced photocatalytic performances and effective wastewater treatment.

A combined molecular dynamic simulation, DFT calculations, and experimental study of the eriochrome black T dye adsorption onto chitosan in aqueous solutions.

This study aims to evaluate and understand the adsorption of eriochrome black T (EB) by chitosan extracted from local shrimp shells under different experimental conditions. Chitosan samples were characterized by XRD, SEM, and FTIR. Experimental results indicate that the process was pH-dependent with a high adsorption capacity in acidic medium. The adsorption was rapid and kinetic data were suitably correlated to the pseudo-second-order kinetic model. EB molecules were adsorbed on monolayer according to the Langmuir model with an adsorption capacity of 162.3 mg/g. On the other hand, it should be noted that calculated quantum chemical parameters support the experimentally obtained results. The interaction energies calculated for (molecule/chitosan) complexes were in the order of H2EB- > HEB2- (O38) > HEB2- (O48) > EB > H3EB > EB3-, which means that the best and possible adsorption process can take place with H2EB- form. The molecular dynamics (MD) approach was performed to illuminate the nature of the relationship between the EB and the chitosan (110) surface. It was found that the chitosan (110) surface adsorbs EB molecule in a nearby parallel orientation. The higher negative adsorption energy determined for the H2EB- implies that the adsorption mechanism is the typical chemisorption.