Ozone-3,6-dihydroxynaphtha-2,7-disulphonate chemiluminescence system is used for online ozone detection.

The chemiluminescence (CL) reaction between ozone and 3,6-dihydroxynaphtha-2,7-disulphonate (DNDS) was found under alkaline conditions. Therefore, a novel CL system for ozone detection was established. The CL signal of the CL system is weak, and the CL signal is enhanced by adding nonionic surfactants. It was found that adding 16.4 g/l Triton X-100 can enhance the CL signal. The CL reagent activated by ultraviolet (UV) light produced a CL signal was nearly 10 times stronger than the CL reagent not activated by UV light; the CL signal was enhanced by adding 8 g/l NaHCO3 to the CL reagent irradiated by UV light. Through the optimization of these test conditions, a high-selectivity, high-sensitivity online detection method for ozone CL was established. The linear range was 0.5-150 ppbv, and the limit of detection (LOD) was 0.092 ppbv (S/N = 3).

SiOC Screens with Aligned and Adjustable Pore Structure for Screen Channel Liquid Acquisition Device.

The development of porous ceramic screens with high chemical stability, low density, and thermal conductivity can lead to promising screen channel liquid acquisition devices (SC-LADs) for propellant management under microgravity conditions in the future. Therefore, SiOC screens with aligned pores were fabricated via freeze-casting and applied as a SC-LAD. The pore window sizes and open porosity varied from 6 µm to 43 µm and 65% or 79%, depending on the freezing temperature or the solid loading, respectively. The pore window size distributions and bubble point tests indicate crack-free screens. On the one hand, SC-LADs with an open porosity of 79% removed gas-free liquid up to a volumetric flow rate of 4 mL s-1. On the other hand, SC-LADs with an open porosity of 65% were limited to 2 mL s-1 as the pressure drop across these screens was relatively higher. SC-LADs with the same open porosity but smaller pore window sizes showed a higher pressure drop across the screen and bubble ingestion at higher values of effective screen area when increasing the applied removal volumetric flow rate. The removed liquid from the SC-LADs was particle-free, thus representing a potential for applications in a harsh chemical environment or broad-range temperatures.

Efficient photocatalytic oxidation of gaseous toluene in a bubbling reactor of water.

Conventional gas-solid photocatalytic oxidation (SPCO) of VOCs has drawbacks such as accumulation of intermediates and catalytic deactivation. In this study, gas-liquid photocatalytic oxidation (LPCO) was exploited to improve the catalytic activity and stability by continuously bubbling VOCs into water. Toluene and commercial TiO2 (P25) were chosen as the representative VOC pollutant and photocatalyst, respectively. Toluene removal efficiency in LPCO was about 6 times of that in conventional SPCO, and no intermediates were detected in the exhaust of LPCO probably due to its high degradation and mineralization rates. However, plentiful intermediates were identified by GC-MS and ITMS both in the gas outlet and on the surface of catalyst in SPCO, which may lead to photocatalytic deactivation. Moreover, LPCO exhibited superior catalytic activity towards typical soluble VOCs such as formaldehyde compared to SPCO. The soluble intermediates formed from toluene degradation can be easily removed by sustaining UV irradiation to avoid water pollution and the water after purification can be reused in LPCO. This study provides a novel gas-liquid photocatalytic oxidation to replace conventional gas-solid photocatalytic oxidation for the sake of better catalytic activity and fewer by-products.