Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several appro...Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.展开更多
The formation of cancinogenic nitrosamines, esp. N-nitrosodimethylamine （NDMA） in water and wastewater treatment plants has drawn much attention in recent years. Dissolved organic matter from the transported Luan Ri...The formation of cancinogenic nitrosamines, esp. N-nitrosodimethylamine （NDMA） in water and wastewater treatment plants has drawn much attention in recent years. Dissolved organic matter from the transported Luan River water as water source of Tianjin was fractionated with different XAD resins and a series of ultra-filtration membranes with molecular weight （MW） cut-offs of 5k Da, 3k Da, and lk Da, respectively. The NDMA yields from the raw water and each fraction were measured to investigate their role in NDMA yield. Results indicated that the hydrophilic fraction had a higher NDMA yield than those of hydrophobic fraction and transphilic fraction. The fraction with MW below lk Da had a higher NDMA yield than that with larger MW. NDMA formation increased as the dissolved organic carbon （DOC） to dissolved organic nitrogen （DON） ratio decreased, which indicated that DON might serve as the real important precursor for NDMA. The correlation between NDMA yield and specific ultraviolet absorbance at 254nm （SUVA254） suggested that the latter might not represent the specific precursors for NDMA in the water. Besides the water quality, the influences of pH, disinfectant dosage, and disinfection contact time on the formation of NDMA were also examined. These results will help water treatment plants establish measures to control this harmful disinfection by-product.展开更多
Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with i...Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with initial concentration of 48μmol/L （20 mg/L） was effectively degraded and 47.8% of fluorine atoms in PFOA molecule were transformed into inorganic fluoride ion after 4 h reaction. Shorter chain perfluorocarboxylic acids bearing C3-C7 and fluoride ion were detected and identified by LC/MS and IC as the degradation products in the aqueous solution. It was proposed that complexes of PFOA with Fe（Ⅲ） initiated degradation of PFOA irradiated with 254 nm UV light.展开更多
针对RTCA DO-254中对于简单电子硬件的符合性表明方式定义不明确的问题,为了解决机载电子设备适航过程中简单电子硬件如何表明对DO-254符合性的问题,通过分析FAA Order 8110.105A中的关于简单电子硬件的符合性验证考虑,重点讨论简单电...针对RTCA DO-254中对于简单电子硬件的符合性表明方式定义不明确的问题,为了解决机载电子设备适航过程中简单电子硬件如何表明对DO-254符合性的问题,通过分析FAA Order 8110.105A中的关于简单电子硬件的符合性验证考虑,重点讨论简单电子硬件的判定方式,符合性验证要求,并结合工作经验探讨具体符合性验证工作。展开更多
基金financial support from Ministry of Science and Technology of the People’s Republic of China (Nos.2016YFE0112200 and 2016YFC0202700)National Natural Science Foundation of China (Nos.21507011,21677037 and 21607027)Natural Science Foundation of Shanghai (Nos. 19ZR1471200,17ZR1440200)
文摘Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.
文摘The formation of cancinogenic nitrosamines, esp. N-nitrosodimethylamine （NDMA） in water and wastewater treatment plants has drawn much attention in recent years. Dissolved organic matter from the transported Luan River water as water source of Tianjin was fractionated with different XAD resins and a series of ultra-filtration membranes with molecular weight （MW） cut-offs of 5k Da, 3k Da, and lk Da, respectively. The NDMA yields from the raw water and each fraction were measured to investigate their role in NDMA yield. Results indicated that the hydrophilic fraction had a higher NDMA yield than those of hydrophobic fraction and transphilic fraction. The fraction with MW below lk Da had a higher NDMA yield than that with larger MW. NDMA formation increased as the dissolved organic carbon （DOC） to dissolved organic nitrogen （DON） ratio decreased, which indicated that DON might serve as the real important precursor for NDMA. The correlation between NDMA yield and specific ultraviolet absorbance at 254nm （SUVA254） suggested that the latter might not represent the specific precursors for NDMA in the water. Besides the water quality, the influences of pH, disinfectant dosage, and disinfection contact time on the formation of NDMA were also examined. These results will help water treatment plants establish measures to control this harmful disinfection by-product.
文摘Environmentally persistent and bioaccumulative perfluorooctanic acid （PFOA） was difficult to be decomposed under the irradiation of 254 nm UV light. However, in the presence of 80μmol/L Fe（Ⅲ）, 80% of PFOA with initial concentration of 48μmol/L （20 mg/L） was effectively degraded and 47.8% of fluorine atoms in PFOA molecule were transformed into inorganic fluoride ion after 4 h reaction. Shorter chain perfluorocarboxylic acids bearing C3-C7 and fluoride ion were detected and identified by LC/MS and IC as the degradation products in the aqueous solution. It was proposed that complexes of PFOA with Fe（Ⅲ） initiated degradation of PFOA irradiated with 254 nm UV light.
文摘针对RTCA DO-254中对于简单电子硬件的符合性表明方式定义不明确的问题,为了解决机载电子设备适航过程中简单电子硬件如何表明对DO-254符合性的问题,通过分析FAA Order 8110.105A中的关于简单电子硬件的符合性验证考虑,重点讨论简单电子硬件的判定方式,符合性验证要求,并结合工作经验探讨具体符合性验证工作。
