Reduced Utilization Process Leaching Toxicity by Stabilizing Heavy Metals in Fly Ash from MSW Incineration Based on Hydrothermal Oxidation.

Hydrothermal oxidation is an effective approach to reduce leaching toxicity of fly ash from municipal solid waste incineration during utilization process. Herein, the effects of temperature, time, pH and Ce-Mn catalyst dosage on the stabilization of heavy metals in fly ash during hydrothermal oxidation were studied. The temperature of hydrothermal oxidation was positively correlated to the stabilization effect. However, the reaction time and pH emerged unstable effect. The amount of Ce-Mn catalyst had a slightly positive effect on the stabilizing at low doses, but it can be inhibited by excessive dose. The leaching concentrations of all heavy metals accorded with National Wastewater Discharge Standard of China (GB 8978-1996) under the optimal parameters, especially for Pb, Ni and Cu. The heavy metals were transformed from unstable fractions to residue fractions during hydrothermal process, among which the proportion of Cu and Zn residue fractions significantly increased and further reduced leaching toxicity.

High-Efficient Visible-Light Photocatalysis Performance and Light-Corrosion Resistance of Ag3PO4 Constructed by double-Z System Composites.

Novel visible-light-driven Ag3PO4/AgBr/AgI photocatalysts were prepared via a simple self-assembly strategy combined with in-situ anion-exchanging process. The photocatalytic activity of Ag3PO4 was significantly improved by constructing double-Z system. Specifically, the obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). Under visible light irradiation (λ > 420 nm), the Ag3PO4/AgBr/AgI photocatalysts showed much higher photocatalytic activity than bulk Ag3PO4 for the degradation of formaldehyde (HCHO), and 100% HCHO degradation could be obtained within 28 min. The degradation efficiency could be maintained in five cycles. Further electron paramagnetic resonance (ESR) tests demonstrated that both •OH and •O2- generated in the system. This study provides new insights into the fabrication of highly efficient visible-light-driven photocatalysts and facilitates their practical application in emerging environment issues.