Photocatalytic degradation of organic dyes by U3MnO10 nanoparticles under UV and sunlight

Sustainable and energy-efficient photocatalytic degradation of textile dye assisted by ecofriendly synthesized silver nanoparticles

In this study, we have touched on two goals of sustainable development, namely, the provision of clean water and sanitation and clean energy at acceptable prices, hoping for good health for all ages. A green economical method was used to prepare silver nanoparticles from chitosan biopolymer. AgNPs were fully characterized using UV-Vis, FTIR, XRD, HR-TEM, and EDX analysis. Different concentrations (0.02-0.18 g/L) of the nanoparticles were integrated into a mixture of heterogeneous nano photocatalysts TiO₂ and ZnO (1:1 weight ratio) under UV irradiation for the photocatalytic degradation of Acid Red 37 textile dye to obtain clean water. The kinetic description of the performed photocatalytic process was presented assuming a pseudo-first-order reaction. The data revealed that increasing the concentration of AgNPs in the catalytic mixture showed a high apparent rate constant (k_app) accompanied by an increase in the apparent quantum yield (%Q_app), followed by dye destruction after a very short time (t_0.5 = 3 min). Since the photocatalytic degradation process consumes electrical energy, the electrical energy per order (EE/O) was calculated, showing a low value of 20 kWh/m³/order, using 0.18 g/L AgNPs, indicating that the elicited photocatalytic degradation method is a sustainable one for the mineralization of the targeted dye.

Photodegradation under UV Light Irradiation of Various Types and Systems of Organic Pollutants in the Presence of a Performant BiPO4 Photocatalyst

In this study, we prepared spheroid microstructures of monoclinic bismuth phosphate BiPO4 by a facile solid-state reaction at 500 °C. The crystal structure was refined using the Rietveld method, where the crystal cell was resolved using a monoclinic system (parameters a, b, c, β) with space group P21/n. SEM images showed that the solid catalyst presented homogeneous morphologies. These BiPO4 microparticles (BiP-500) have been used as photocatalysts to photodegrade, under UV light irradiation, three cationic dyes (Rhodamine B, RhB; Methylene Blue, MB; and Toluidine Blue, TB), three anionic dyes (Congo Red, CR; Orange G, OG; and Methyl Orange, MO) and mixtures of RhB-MB, RhB-OG and MO-OG organic dyes. The photodegradation efficiency of these BiP-500 microparticles is found to be optimal in the case of RhB solutions, RhB-MB and RhB-OG binary mixtures. The BiP-500 catalyst shows a high selectivity for the conversion of the mixture of dyes into CO2 and H2O. Total organic carbon analysis of an anionic dye and a cationic dye (RhB, OG and RhB-MB) confirms the mineralization of the pollutants in the presence of BiP-500 particles. The photocatalytic efficiency of our BiP-500 photocatalyst has been confirmed, with a view to facilitate applications in the field of the depollution of wastewater in the agricultural environment by the degradation of parathion-methyl (PM) as a pollutant.

Enhanced Sonocatalytic Performance of Non-Metal Graphitic Carbon Nitride (g-C3N4)/Coconut Shell Husk Derived-Carbon Composite

This study focused on the modification of graphitic carbon nitride (g-C3N4) using carbon which was obtained from the pyrolysis of coconut shell husk. The sonocatalytic performance of the synthesized samples was then studied through the degradation of malachite green. In this work, pure g-C3N4, pure carbon and carbon/g-C3N4 composites (C/g-C3N4) at different weight percentages were prepared and characterized by using XRD, SEM-EDX, FTIR, TGA and surface analysis. The effect of carbon amount in the C/g-C3N4 composites on the sonocatalytic performance was studied and 10 wt% C/g-C3N4 showed the best catalytic activity. The optimization study was conducted by using response surface methodology (RSM) with a central composite design (CCD) model. Three experimental parameters were selected in RSM including initial dye concentration (20 to 25 ppm), initial catalyst loading (0.3 to 0.5 g/L), and solution pH (4 to 8). The model obtained was found to be significant and reliable with R2 value (0.9862) close to unity. The degradation efficiency of malachite green was optimized at 97.11% under the conditions with initial dye concentration = 20 ppm, initial catalyst loading = 0.5 g/L, solution pH = 8 after 10 min. The reusability study revealed the high stability of 10 wt% C/g-C3N4 as sonocatalyst. In short, 10 wt% C/g-C3N4 has a high potential for industrial application since it is cost effective, reusable, sustainable, and provides good sonocatalytic performance.