ABSTRACT
In order to understand the sources and distribution characteristics of hexachlorobutadiene (HCBD) in the Yangtze River Delta (YRD), Beijing-Tianjin-Hebei (BTH), and Pearl River Delta (PRD), the emission sources, as well as their distribution in water and soil were analyzed based on the production levels of chlorinated hydrocarbons and wastewater discharge in the three regions. The results showed that the by-products of trichloroethylene (TCE) and tetrachloroethylene (PCE) and wastewater treatment plants were the main sources of HCBD in the three regions. In 2018, the total emissions of HCBD from by-products of TCE and PCE in the three regions were 498.46 t, among which the proportion of by-products of TCE was 66.9%. The HCBD emissions of the three regional industrial and domestic wastewater treatment plants were 628.9 kg and 254.6 kg, respectively. The emissions of HCBD from hydrocarbon chlorination production and wastewater treatment plants in YRD were significantly higher at 497.8 t and 648 kg, respectively, while the emissions from the two sources in BTH were 0.37 t and 125 kg, respectively, and in PRD they were 0.29 t and 110.3 kg, respectively. The average concentrations of HCBD in the natural water of YRD, BTH and PRD were 0.35, 0.25, and 0.64 µg·L-1, respectively, and in the drinking water concentrations were 0.16, 0.09, and 0.04 µg·L-1, respectively. The overall level of HCBD in urban drinking water was relatively low. The concentrations of HCBD in industrial soil were significantly higher than in farmland soil, at 9.3-24.6 ng·g-1 and 0.13-2.67 ng·g-1, respectively. Similar to the situation in water bodies, HCBD pollution in the soil of YRD was the most serious, which was related to the fact that HCBD emissions in YRD were significantly higher than in BTH and PRD.
ABSTRACT
Persistent organic pollutants (POPs) have gained heightened attentions in recent years owing to their persistent property and hazard influence on wild life and human beings. Removal of POPs using varieties of multifunctional materials have shown a promising prospect compared with conventional treatments. Herein, three main categories, including thermal degradation, electrochemical remediation, as well as photocatalytic degradation with the use of diverse catalytic materials, especially the recently developed prominent ones were comprehensively reviewed. Kinetic analysis and underlying mechanism for various POPs degradation processes were addressed in detail. The review also systematically documented how catalytic performance was dramatically affected by the nature of the material itself, the structure of target pollutants, reaction conditions and treatment techniques. Moreover, the future challenges and prospects of POPs degradation by means of multiple multifunctional materials were outlined accordingly. Knowing this is of immense significance to enhance our understanding of POPs remediation procedures and promote the development of novel multifunctional materials.
