聚合硅酸硫酸铝铁的制备与应用

在n(Fe A1)／n(Si)为0．5～1．0、n(Al)／n(Fe)为2．5～3．0、SiO2质量分数为2．3％、硅酸钠溶液的活化pH为5．5、硅酸钠溶液的活化时间为12min或SiO2的质量分数为2．0％、硅酸钠溶液的活化pH为6．0、硅酸钠溶液的活化时间为3min的条件下，制备出的聚合硅酸硫酸铝铁对废水的除浊效果最佳，除浊率大于98％。     

生物降解高分子材料的研究现状及应用前景

目前,处理高分子材料的一些传统方法,如焚烧法、掩埋法、熔融共混挤出法、回收利用等都存在一定的缺陷和局限性,给环境保护带来严重的困难。因此,开发环境可接受的降解性高分子材料是解决环境污染的重要途径。生物降解高分子是指通过自然界或添加的微生物的化学作用,将高分子物质分解成小分子化合物,再进入自然的循环过程。论述了生物降解高分子材料的研究现状,并对生物降解高分子材料的降解机理、影响因素及其在医学、农业、包装业和其他领域的潜在应用前景进行了探讨。     

The influence of low-dose cadmium on the laryngeal microstructure and ultrastructure of Pelophylax nigromaculata

Environmental Science and Pollution Research - Cadmium (Cd) is one of the common heavy metals dispersed throughout the modern environment that disrupts the development of aquatic organisms....     

Precursors and potential sources of ground-level ozone in suburban Shanghai

• Air masses from Zhejiang Province is the major source of O₃ in suburban Shanghai. • O₃ formation was in VOC-sensitive regime in rural Shanghai. • O₃ formation was most sensitive to propylene in rural Shanghai. A high level of ozone (O₃) is frequently observed in the suburbs of Shanghai, the reason for this high level remains unclear. To obtain a detailed insight on the high level of O₃ during summer in Shanghai, O₃ and its precursors were measured at a suburban site in Shanghai from July 1, 2016 to July 31, 2016. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and concentration weighted trajectories (CWT), we found that Zhejiang province was the main potential source of O₃ in suburban Shanghai. When the sampling site was controlled by south-western winds exceeding 2 m/s, the O₃-rich air masses from upwind regions (such as Zhejiang province) could be transported to the suburban Shanghai. The propylene-equivalent concentration (PEC) and ozone formation potential (OFP) were further calculated for each VOC species, and the results suggested that propylene, (m+p)-xylene, and toluene played dominant roles in O₃ formation. The Ozone Isopleth Plotting Research (OZIPR) model was used to reveal the impact of O₃ precursors on O₃ formation, and 4 base-cases were selected to adjust the model simulation. An average disparity of 18.20% was achieved between the simulated and observed O₃ concentrations. The O₃ isopleth diagram illustrated that O₃ formation in July 2016 was in VOC-sensitive regime, although the VOC/NO_x ratio was greater than 20. By introducing sensitivity (S), a sensitivity analysis was performed for O₃ formation. We found that O₃ formation was sensitive to propylene, (m+p)-xylene, o-xylene and toluene. The results provide theoretical support for O₃ pollution treatment in Shanghai.     

Facile in situ synthesis of silver nanocomposites based on cellulosic paper for photocatalytic applications

Environmental Science and Pollution Research - In this work, various photocatalysts were synthesized with an impregnation-precipitation process to in situ decorate Ag-based nanoparticles (NPs,...     

Effect of straw retention on carbon footprint under different cropping sequences in Northeast China

Environmental Science and Pollution Research - Inappropriate farm management practices can lead to increased agricultural inputs and changes in atmospheric greenhouse gas (GHG) emissions, impacting...     

Ambient volatile organic compounds pollution in China

Owing to rapid economic and industrial development, China has been suffering from degraded air quality and visibility. Volatile organic compounds (VOCs) are important precursors to the formation of ground-level ozone and hence photochemical smog. Some VOCs adversely affect human health. Therefore, VOCs have recently elicited public concern and given new impetus to scientific interest. China is now implementing a series of polices to control VOCs pollution. The key to formulating policy is understanding the ambient VOCs pollution status. This paper mainly analyzes the species, levels, sources, and spatial distributions of VOCs in ambient air. The results show that the concentrations of ambient VOCs in China are much higher than those of developed countries such as the United States and Japan, especial benzene, which exceeds available standards. At the same time, the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of various VOCs are calculated. Aromatics and alkenes have much higher OFPs, while aromatics have higher SOAFP. The OFPs of ambient VOCs in the cities of Beijing, Guangzhou and Changchun are very high, and the SOAFP of ambient VOCs in the cities of Hangzhou, Guangzhou and Changchun are higher.     

Effect of barium sulfate modification on the SO2 tolerance of V2O5 /TiO2 catalyst for NH3-SCR reaction

Sulfur poisoning of V_2O_5/BaSO_4–TiO_2(VBT),V_2O_5/WO_3–TiO_2(VWT) and V_2O_5/BaSO_4–WO_3–TiO_2(VBWT) catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reduction of NO_x with NH_3 were evaluated for 200–500℃.The VBT catalyst showed higher NO_x conversions after sulfur poisoning than the other two catalysts.The introduction of barium sulfate contributed to strong acid sites for the as-received catalyst,and eliminated the redox cycle of active vanadium oxide to some extent,which resulted in a certain loss of activity.Readily decomposable sulfate species formed on VBT-S instead of inactive sulfates on VWT-S.These decomposable sulfates increased the number of strong acid sites significantly.Some sulfate species escaped during catalyst preparation and barium sulfate was reproduced during sulfur poisoning,which protects vanadia from sulfur oxide attachment to a great extent.Consequently,the VBT catalyst exhibited the best resistance to sulfur poisoning.     

Pollutant emission characteristics of rice husk combustion in a vortexing fluidized bed incinerator

Rice husk with high volatile content was burned in a pilot scale vortexing fluidized bed incinerator. The fluidized bed incinerator was constructed of 6 mm stainless steel with 0.45 m in diameter and 5 m in height. The emission characteristics of CO, NO, and SO2 were studied. The effects of operating parameters, such as primary air flow rate, secondary air flow rate, and excess air ratio on the pollutant emissions were also investigated. The results show that a large proportion of combustion occurs at the bed surface and the freeboard zone. The SO2 concentration in the flue gas decreases with increasing excess air ratio, while the NOx concentration shows reverse trend. The flow rate of secondary air has a significant impact on the CO emission. For a fixed primary air flowrate, CO emission decreases with the secondary air flowrate. For a fixed excess air ratio, CO emission decreases with the ratio of secondary to primary air flow. The minimum CO emission of 72 ppm is attained at the operating condition of 40% excess air ratio and 0.6 partition air ratio. The NOx and SO2 concentrations in the flue gas at this condition are 159 and 36 ppm, which conform to the EPA regulation of Taiwan.