SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Shengyan Jin,Lingdong Kong,Kejing Yang,Chao Wang,Lianghai Xia,Yuwen Wang,Jie Tan,Lin Wang
Free radicals and nitrogen-containing species produced by nitrate photolysis can affect various atmospheric chemical processes, and thereby the photochemical behavior of atmospheric nitrate aerosols has been attracting much attention. However, the photolysis mechanism of NH 4 NO 3 and its products under different atmospheric conditions remain unclear. In this study, the effects of relative humidity (RH), pH, NH 3 , ultraviolet (UV) light intensity and halogen ions (Cl − , Br − and I − ) on the photolysis of particulate NH 4 NO 3 have been investigated through a flow tube reactor. The results show that RH can significantly enhance the production of gaseous NO 2 from the photolysis of NH 4 NO 3 when RH is higher than its deliquescence RH, but almost no NO 2 is generated under dry conditions. Under high RH and UV light, the main product of NH 4 NO 3 photolysis is NO 2 , rather than NO and HONO, and another main species HNO 3 which mainly comes from the hydrolysis of product NO 2 in the gas path was detected. Almost no NO 2 and HNO 3 are produced under high RH without UV light or low RH with UV light, showing the combined effect of high RH and UV irradiation on the photolysis of NH 4 NO 3 . In addition, under high RH, the lower the pH and the stronger the light intensity, the higher the NO 2 production. Furthermore, surprising yields of NO and HONO are detected in the presence of halogen ions, especially in the presence of I − , indicating the important role of halogen ion in the nitrate photolysis. These results provide new insights into the photolysis of atmospheric nitrate aerosols, and may contribute to elucidating the formation and migration of atmospheric nitrate aerosols and the potential mechanisms of the occurrence and evolution of atmospheric pollution and ozone pollution.
研究领域:
大气化学
·
环境科学
✓ 已验证
DOI
高影响因子
ADVANCES IN ATMOSPHERIC SCIENCES
·
2021
·Vol. 38
·期 7
·1238-1251
·
IF 3.158
Zhang Hailiang,Xu Yongfu,Jia Long,Xu Min
Acetaldehyde is one of the important VOC species of O 3 precursors in the atmospheric environment. The influences of relative humidity (RH) and initial VOC/NO x ratio ( R CN ) on the formation of O 3 are studied in smog chamber experiments, and the MCM v3.3.1 mechanism of acetaldehyde is modified based on the experimental results. In low-RH conditions (RH = 11.6%±1.1%), the O 3 concentration at 6 h increases first and then decreases with the increase of R CN , and the R CN at the inflection point of O 3 concentrations is 3.2. In high-RH experiments (RH = 78.8%±1.0%), variation of the O 3 concentration at 6 h with R CN is similar to that in low-RH experiments, but the R CN at the inflection point is 2.8. RH has no significant effect on the O 3 concentrations under low R CN (< 3), whereas it has a negative effect under high R CN (> 3). Compared with the experimental results, original MCM v3.3.1 greatly underestimates the O 3 concentrations. Addition of both the photolysis process of peroxyacetyl nitrate and the photolysis process of HNO 3 on the reactor surface into the original MCM can reduce the difference between the simulated O 3 concentrations and the experimental results at 6 h from 24%−35% and 17%−49% to 6%−26% and 10%−42% under low- and high-RH conditions, respectively. The maximum incremental reactivity (MIR) of acetaldehyde simulated with the modified MCM is 4.0 ppb ppb −1 without considering the effect of other VOCs.
研究领域:
大气科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Xiangjin Zhu,Yaoyu Zhang,Yuxiong Wang,Yue Liu,Zhongbiao Wu
Indoor VOCs pollution has attracted broad attention for its harm to mankind’s health recent years. Photocatalytic degradation of indoor VOCs holds great prospects in addressing these health concerns in daily life. However, traditional photocatalysts have a large recombination rate of charge carriers and a decrease of the photocatalytic degradation efficiency under high relative humidity. Herein, uniform tungsten oxide nanoparticles with enriched oxygen vacancies (WO 3 -U) were synthesized by a direct annealing method with urea addition, which exhibited superior performance in the visible-light photocatalysis. The reaction rate constant value of photocatalytic acetaldehyde degradation over WO 3 -U catalyst was above 3 times higher than that of pristine WO 3 sample. More importantly, the WO 3 -U catalyst maintained stable and excellent photocatalytic performance at relative humidity range of 25–100 %. Except for the enhanced photogenerated charges separation, abundant oxygen vacancies could effectively accelerate O 2 activation to generate •O 2 − , which accounted mainly for the initial conversion of acetaldehyde. Then the subsequent transformation of •O 2 − into •OH to promoted the final mineralization of acetaldehyde. In addition, the presence of oxygen vacancies also facilitated H 2 O dissociation to form surface hydroxyl groups, which increased the adsorption of acetaldehyde, resulting in the consistent photocatalytic performance of WO 3 -U catalyst within a wide humidity range. This work provides guidelines to design visible-light responsive photocatalysts with efficient activity at high humidity conditions for indoor VOCs degradation.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2024
·
IF 8.4
Ke Xiang,Zhen-Liang Xu,Yong-Jian Tang
Recent studies have shown that the temperature and time of the heat curing process have important effects on the nanofiltration (NF) membrane structure and properties. However, the mechanism of the relative humidity (RH), as one of the important factors in the heat curing of NF membranes, is still unclear. To analyze the specific effect of RH, we compared the heat curing results of the NF polyamide (PA) membranes fabricated with different monomer concentrations at various RH. The nanofiltration performance of the membranes appeared to be non-uniform when the RH was in the range of 40 %–60 %. Within the appropriate RH range , the rejection of Na 2 SO 4 was preserved at about 98.5 % for the manufactured NF membranes. At high concentrations, the increasing RH created a discontinuous condensate layer on the PA layer surface, which affected the morphology and physicochemical properties of the NF membrane causing a doubling of pure water permeability (PWP) to 8.33 L m −2 h −1 ·bar −1 . At low concentrations, the PA layer was not significantly changed with the increase of RH, but the evaporation of water from the smaller capillary pores in its PES substrate was slowed down, which reduced the capillary stress on the substrate and prevented the collapse of the substrate pore size, resulting in a nearly 20 times increase in its PWP to 39.7 L m −2 h −1 ·bar −1 . This work reveals the effect of RH during heat curing and gives significant guidance to the design and synthesis of high-performance NF membranes.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Xiaoming Wang,Xingeng Li,Xuelei Tian,Kai Guo
Both the effect of forming conditions on corrosion resistance of phytic acid conversion coating on zinc in air and the influence of ambient factors (temperature and relative humidity) on service of conversion coating were studied by SEM, EDS, ACM and SKP. Zinc-graphite ACM sensors and zinc plates were treated with phytic acid solution at different processing time and pH values. The results showed that longer processing time and alkalinity phytic acid solution weaken the corrosion resistance of treated zinc. Self-assembled monolayer of zinc phytate provided the best protection. The corrosion resistance of conversion coating with phytic acid solution was reduced when the ambient temperature or relative humidity is high values, which due to the zinc phytate bond strength with zinc matrix and co-adoption water on it.
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2024
·
IF 8.5
Chuanxiang Cheng,Yujie Lei,Tiantian Min,Yushan Zhang,Jin Yue
4-Terpineol (4-TA), a typical monocyclic monoterpene essential oil compound with important biological activities, poor stability and solubility severely hamper its biological activities. To date, β-cyclodextrin (β-CD) encapsulating essential oil to form inclusion complexes (ICs) is considered as a satisfactory treatment. Nevertheless, the detailed inclusion mechanism of β-CD for 4-TA especially the behavior of 4-TA during inclusion formation have not available yet. Herein, 4-TA/β-CD ICs were successfully synthesized by the co-precipitation method, and hydrogen bonds and hydrophobic interactions played a key role in the formation of ICs, and the isopropyl of 4-TA entered the cavity through the wide rim of β-CD. Moreover, the release profile demonstrated that high RH (85 % and 99 %) triggered the release of TA from ICs. This study suggests the great potential of cyclodextrin inclusion strategy for improving the stability and sustained release of 4-TA in food preservation application.
研究领域:
食品科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 59
·34465-34471
·
IF 3.049
Xinxing Lin,Wei Ma,Lihui Chen,Liulian Huang,Hui Wu,Atsushi Takahara
The porous shell structure of liquid marbles allows liquid vapor to enter in/out of the liquid marbles, leading to the deformation/collapse of liquid marbles, which limits their application as miniature reactors for long-term chemical reactions. In this study, to prevent volatilization and maintain long-term stability, stable liquid marbles were fabricated by encapsulating glycerol/water droplets using superhydrophobic cellulose nanocrystals. The influence of water evaporation and absorption on the stability of aqueous glycerol marbles at different relative humidities (RHs) was investigated. At the same RH, the evaporation/absorption rates of the liquid marbles decreased on increasing the glycerol concentration. For the liquid marbles with the same glycerol volume concentration, the evaporation rates decreased with the increase in RH. The liquid marbles exhibited higher evaporation/absorption resistance compared with pure naked liquid droplets.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RARE METALS
·
2021
·Vol. 41
·期 1
·37-44
·
IF 4.003
Shi Ze-Di,Zhang Le,Ma Yue-Long,Zhou Tian-Yuan,Sun Bing-Heng,Shao Cen,Huang Guo-Can,Yin Shi-Tong,Hou Su-Dan,Yang Zeng-Wang,Chen Hao
银作为一种功能性材料, 由于其优良的导电性而用作于汽车电子的电接触材料。但是, 这种材料极易遭受大气腐蚀问题, 并导致结构的损坏和器件的失效。本文研究了应用于印刷电路板中导电银的腐蚀行为, 并从动力学和机理方面发现了影响材料结构损害最主要的环境因素(SO 2 污染物、温度和相对湿度(RH, Relative humidity))。相较于其他因素, 温度(55 °C)是运行环境中引起导电材料结构变化的最主要因素, 并且表面的腐蚀层厚度达到了最大值, 即 d film =15.56× 10 -5 μm。然而, 在腐蚀过程中, SO 2 污染物和RH促进了腐蚀物质的扩散, 并也会增加腐蚀产物层(Ag 2 S和Ag 2 SO 4 )的厚度。因此, 本文不仅大大增强了人们对于不同环境因素下导电材料结构损害的认识, 同时也为实际生产中的防腐设计和材料选择提供了重要的指导。 Graphical abstract
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
Frontiers of Environmental Science & Engineering
·
2014
·Vol. 10
·期 2
·219-228
·
IF 0.881
Zhao Pu,Zhu Lizhong
Adsorption is the most widely used technology for the removal of indoor volatile organic compounds (VOCs). However, existing adsorbent-based technologies are inadequate to meet the regulatory requirement, due to their limited adsorption capacity and efficiency, especially under high relative humidity (RH) conditions. In this study, a series of new porous clay heterostructure (PCH) adsorbents with various ratios of micropores to mesopores were synthesized, characterized and tested for the adsorption of acetaldehyde and toluene. Two of them, PCH25 and PCH50, exhibited markedly improved adsorption capability, especially for hydrophilic acetaldehyde. The improved adsorption was attributed to their large micropore areas and high micropore-to-mesopore volume ratios. The amount of acetaldehyde adsorbed onto PCH25 at equilibrium reached 62.7 mg·g −1 , eight times as much as the amount adsorbed onto conventional activated carbon (AC). Even at a high RH of 80%, PCH25 removed seven and four times more of the acetaldehyde than AC and the unmodified raw PCHs did, respectively. This new PCH optimized for their high adsorption and resistance to humidity has promising applications as a cost-effective adsorbent for indoor air purification.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Mingwei Feng,Juan Wang,Shu Liu,Dariusz Wanatowski,Yong Ren
Xanthan gum, as an environment-friendly biopolymer, holds great promise to replace conventional binders for engineering construction. Yet, the impact of curing temperature and relative humidity (RH) on the strength of xanthan gum-treated sand remains uncertain. In this study, xanthan gum-treated sand specimens were cured under different temperatures (20°C-70°C) and RH (10 %-80 %), respectively, until an equilibrium moisture content was reached. Through a series of Unconfined Compressive Strength (UCS) tests, an optimal curing humidity of 40 % was identified for all the testing temperatures. It was also found the UCS at 10 % RH is always slightly higher than that at 70 % RH, and the UCS increases linearly with the curing temperature under the same RH. The mechanisms of the findings were further studied by X-ray Computed Tomography (CT) scan tests and Scanning Electron Microscopy (SEM) tests. The strengthening of xanthan gum-treated sand was attributed to an internal hydrogel effect and an external hydrogel-particle network effect. In particular, the hydrogel breakage at low RH and the small hydrogel volume at high RH contribute negatively to the network effect and thus relatively small UCS at low/high RH. Meanwhile, elevating the curing temperature could trigger the conformation transformation of xanthan gum hydrogels and thicken the shells of hydrogels, both of which contribute positively to the hydrogel and network effects and thus provide a higher UCS.
研究领域:
土木工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Teng Chen,Xin Xu,Jianqiang Hu,Li Guo,Shizhao Yang,Tianxiang Zhao,Jun Ma
Water contamination in aviation jet fuel has been a particular concern throughout the aviation industry for many decades on account of any contaminating water may accelerate the corrosion of the aircraft fuel systems, diminish the lubricative properties of the fuel, promote microorganism growth, and more importantly, pose threat to flight safety. However, the water behavior of jet fuel has not been studied systematically so far, especially for the free water, which is the main factor that causes the hazards mentioned above. Herein, the water behaviors, including dissolved and free water behaviors versus storage time, temperature, relative humidity and anti-icing agent are investigated. Compared with storage time, temperature and relative humidity have a greater influence on the water solubility, and the respective exponential and linear relationships between the solubility of water and temperature and relative humidity are identified in this paper. Furthermore, a complete discussion is carried out on the effect of anti-icing agent on the solubility of water and free water content in jet fuel. More importantly, the real water behavior of jet fuel with anti-icing agent is also studied through simulating the variation in temperature during flight.
研究领域:
航空工程
·
化学工程
✓ 已验证
DOI
高影响因子
ATMOSPHERIC ENVIRONMENT
·
2022
·
IF 5.755
Xi Xi,Xiang He,Zhi-Cheng Ma,Hui-Qing Ma,Peng-Cheng Liao
Formation processes of nitrogen-containing organic compounds (NOCs) are important from heterogeneous reactions between volatile organic compounds (VOCs) and mineral oxides under various environmental factors. In this study, reaction processes of C 3 H 6 /O 3 /NO 2 with α-Fe 2 O 3 particles were studied by using a gas-flow system with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the appearance of R–ONO 2 bands at ∼1648 and 1286 cm −1 represents the formation of NOCs. In the dark condition, the presence of O 3 leads to the rapid formation of nitrate radical (NO 3 ) which can react with C 3 H 6 to form NOCs on particle surface. Under the simulated sunlight irradiation, the α-Fe 2 O 3 can be excited to produce additional hydroxyl which promotes the formation of RO 2 . Meanwhile, formed NO from the photolysis of NO 2 can react with RO 2 to produce more NOCs. Moreover, the presence of water vapor plays a negative role in the NOCs formation processes. The value of uptake coefficient for the NO 2 in the initial stage at 0% relative humidity (RH) is about 10 times higher than that at 76.3% RH during the heterogeneous reactions. The R–ONO 2 group hydrolyzes to nitric acid and R–OH under the humid condition. Our results lay the foundation on the effects of light irradiation and RH for the converting VOCs into NOCs on mineral dust and help to understand the formation processes of NOCs under combined atmospheric environment.
研究领域:
大气化学
·
环境科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）