Photocatalytic degradation of ammonia with titania nanoparticles under UV light irradiation.

Ammonia is one of the major pollutants of water resources, posing a serious threat to human health and the environment. Titania nanoparticles were used to examine the photocatalytic degradation of ammonia from an aqueous solution in this study. Titania nanoparticles (NPs) were first synthesized via the sol-gel method, then characterized using XRD, FTIR, DLS, EDX, FE-SEM, and TEM analyses. Four effective parameters (pH, initial concentration of pollutant, catalyst dosage, and irradiation time) for photocatalytic degradation were explored using Design-Expert Software. The greatest photocatalytic activity of titania NPs was found in optimal conditions, according to the findings (97%). The optimum amounts of catalyst dosage, initial pollutant concentration, irradiation time, and pH were obtained at 0.3 g/l, 1500 mg/l, 120 min, and 12, respectively. Furthermore, studies revealed that pH was the most efficient variable in comparison with others and that increasing the pH value from 8 to 12 boosted ammonia removal from 40 to 97%. NPs showed high stability as the ammonia removal decreased from 96.96% to 65% after four cycles. Generally, this research has created a precedent for the development of morphology-dependent photocatalysts for the degradation of organic contaminants.

Heterogeneous photo-Fenton degradation of formaldehyde using MIL-100(Fe) under visible light irradiation.

Removal of toxic formaldehyde from environmental waters is crucial to maintain ecosystem sustainability and human health. In this work, MIL-100(Fe) as a heterogeneous Fenton-like photocatalyst was used for the treatment of formaldehyde-contaminated water. The MIL-100(Fe) was synthesized via a facile solvothermal method and fully characterized using different spectroscopic and microscopic techniques. Based on the results, the formation of highly porous, crystalline, and stable visible light-responsive MIL-100(Fe) was confirmed. The Fenton-like photocatalytic efficiency of the MIL-100(Fe) toward the degradation of formaldehyde was then studied under visible light irradiation. For this purpose, the effect of initial concentration of formaldehyde, photocatalyst dose, H2O2 concentration, solution pH, and contact time on the removal efficiency of the MIL-100(Fe) was investigated using central composite design. The obtained results showed that the removal efficiency of the MIL-100(Fe) is significantly affected by the initial concentration of formaldehyde. A second-order model with R2 = 0.93 was developed for the system that was able to adequately predict the percentage removal of formaldehyde by the MIL-100(Fe) under different experimental conditions. According to the numerical optimization results, by using 1.13 g L-1 photocatalyst and 0.055 mol L-1 H2O2, 93% of formaldehyde can be removed after 119 min from an aqueous solution containing 700 mg L-1 of formaldehyde at pH 6.54.