Ozone-based technologies are used for micro-pollutants removal in wastewater treatment. However, the generation of the toxic by-product bromate (BrO3−) is of a great concern. LaCoO3 (LCO) catalytic ozonation has been used to overcome this significant drawback in the sole ozonation, achieving better BrO3− elimination efficiency. However, a key challenge is how to enhance micro-pollutant (benzotriazole, BZA) degradation efficiency and to eliminate formed BrO3− synchronously under various water qualities in drinking water or wastewater treatment. Therefore, the objective of this study is to propose a practical strategy of BZA removal and BrO3− reduction synchronously in water or wastewater treatment. In this study, important factors influencing BZA removal and BrO3− reduction were investigated, including [catalyst], [BZA], initial pH solution, [NH4+-N] and [(bi)carbonate alkalinity]. Based on the performance and mechanism of these effects, a practical strategy for BZA degradation and BrO3− elimination with and without Br− in the influent was developed. Additionally, the density functional theory (DFT) calculation successfully predicted the attack site on BZA by molecular ozone and formed hydroxyl radical (HO·) during LCO catalytic ozonation. Fukui indexes of f+ and f0 were calculated to forecast direct ozone molecule and HO· attack, respectively. Combination of DFT calculation with intermediates that identified through liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS), BZA degradation pathway was established more accurately. Additionally, four new intermediates were identified in this study. Overall, this study proposes a useful strategy for synchronous micro-pollutants degradation and BrO3− elimination, while also suggesting the feasibility of LCO catalytic ozonation for water or wastewater purification.
Up to now, titanium dioxide (TiO2) is the most established semiconductor photocatalyst, which is used to achieve photocatalytic H2 evolution, pollutants degradation, CO2 reduction, and N2 reduction under UV light irradiation. TiO2 as photocatalyst is always under the spotlight due to its unique properties like outstanding thermal/chemical stability, wide bandgap with suitable band edge, low cost, non-toxicity, and corrosion resistance. To further improve the photocatalytic activity of TiO2, the versatile and porous metal-organic frameworks (MOFs) can be introduced to constructionTiO2/MOF composites, which can accomplish the enhanced light absorption performance and improved electron-hole pair separation. With this review, the fabrication strategies, characterizations techniques, photocatalytic activities and the mechanisms of some selected TiO2/MOF composites were reviewed and highlighted. The last but not the least, the outlooks and challenges of TiO2/MOF composites as photocatalysts for energy conversion and environment remediation are proposed.
Abstract Thermal radiation from a black body increases with the fourth power of absolute temperature (T4), an effect known as the Stefan–Boltzmann law. Typical materials radiate heat at a portion of this limit, where the portion, called integrated emissivity (εint), is insensitive to temperature (|dεint/dT| ≈ 10-4 °C–1). The resultant radiance bound by the T4 law limits the ability to regulate radiative heat. Here, an unusual material platform is shown in which εint can be engineered to decrease in an arbitrary manner near room temperature (|dεint/dT| ≈ 8 × 10-3 °C–1), enabling unprecedented manipulation of infrared radiation. As an example, εint is programmed to vary with temperature as the inverse of T4, precisely counteracting the T4 dependence; hence, thermal radiance from the surface becomes temperature-independent, allowing the fabrication of flexible and power-free infrared camouflage with unique advantage in performance stability. The structure is based on thin films of tungsten-doped vanadium dioxide where the tungsten fraction is judiciously graded across a thickness less than the skin depth of electromagnetic screening.