Research on China’s Risk of Housing Price Contagion Based on Multilayer Networks

The major issue in the evolution of housing prices is risk of housing price contagion. To model this issue, we constructed housing multilayer networks using transfer entropy, generalized variance decomposition, directed minimum spanning trees, and directed planar maximally filtered graph methods, as well as China’s comprehensive indices of housing price and urban real housing prices from 2012 to 2021. The results of our housing multilayer networks show that the topological indices (degree, PageRank, eigenvector, etc.) of new first-tier cities (Tianjin, Qingdao, and Shenyang) rank higher than those of conventional first-tier cities (Beijing, Shanghai, Guangzhou, and Shenzheng)

Enhanced Degradation of Trichloroethene by Sodium Percarbonate Activated with Fe (II) in the Presence of Citric Acid

Trichloroethene (TCE) degradation by Fe(II)-activated sodium percarbonate (SPC) in the presence of citric acid (CA) in aqueous solution was investigated. The results indicated that the presence of CA enhanced TCE degradation significantly by promoting HO• generation. The presence of Cl−, HCO3− and the initial solution pH appeared to be not negligible on the effect of TCE oxidation, while humic acid had no influence on TCE degradation. The generation of HO• and O2−• in the SPC/Fe(II)/CA system was confirmed with chemical probes, and the radical scavenging tests showed that TCE degradation was due to direct oxidation by HO•. Acidic pH condition was favorable for TCE degradation. In summary, this study provided detailed information for the application of the CA-enhanced Fe(II)-activated SPC technique for TCE-contaminated groundwater remediation

Perchloroethylene (PCE) Oxidation by Percarbonate in Fe2+- Catalyzed Aqueous Solution: PCE Performance and Its Removal Mechanism

The performance of Fe2+-catalyzed sodium percarbonate (SPC) stimulating the oxidation of perchloroethylene (PCE) in groundwater remediation was investigated. The experimental results showed that PCE could be completely oxidized in 5min at 20°C with a Fe2+/SPC/PCE molar ratio of 8/8/1, indicating the effectiveness of Fe2+-catalyzed SPC oxidation for PCE degradation. Fe2+-catalyzed SPC oxidation was suitable for the nearly neutral pH condition, which was superior to the conventional Fenton oxidation in acidic condition. In addition, the investigations by using hydroxyl radical scavengers and free radical probe compounds elucidated that PCE was degraded mainly by hydroxyl radical (HO) oxidation in Fe2+/SPC system. In conclusion, Fe2+-catalyzed SPC oxidation is a highly promising technique for PCE-contaminated groundwater remediation, but more complex constituents in groundwater should be carefully considered for its practical application