The corona of a surface bubble promotes electrochemical reactions

AbstractThe evolution of gaseous products is a feature common to several electrochemical processes, often resulting in bubbles adhering to the electrode’s surface. Adherent bubbles reduce the electrode active area, and are therefore generally treated as electrochemically inert entities. Here, we show that this general assumption does not hold for gas bubbles masking anodes operating in water. By means of imaging electrochemiluminescent systems, and by studying the anisotropy of polymer growth around bubbles, we demonstrate that gas cavities adhering to an electrode surface initiate the oxidation of water-soluble species more effectively than electrode areas free of bubbles. The corona of a bubble accumulates hydroxide anions, unbalanced by cations, a phenomenon which causes the oxidation of hydroxide ions to hydroxyl radicals to occur at potentials at least 0.7 V below redox tabled values. The downhill shift of the hydroxide oxidation at the corona of the bubble is likely to be a general mechanism involved in the initiation of heterogeneous electrochemical reactions in water, and could be harnessed in chemical synthesis.

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Dissolution of metallic platinum as water soluble species by naturally occurring complexing agents

Microchimica Acta ◽

10.1007/bf01244740 ◽

1998 ◽

Vol 129 (3-4) ◽

pp. 189-194 ◽

Cited By ~ 57

Author(s):

S�nnke Lustig ◽

Shuliang Zang ◽

Wollgong Beck ◽

Peter Schramel

Keyword(s):

Water Soluble ◽

Complexing Agents ◽

Metallic Platinum ◽

Naturally Occurring ◽

Soluble Species

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Supplementary material to "Synergistic effect of water-soluble species and relative humidity on morphological changes of aerosol particles in Beijing mega-city during severe pollution episodes"

10.5194/acp-2018-623-supplement ◽

2018 ◽

Author(s):

Xiaole Pan ◽

Baozhu Ge ◽

Zhe Wang ◽

Yu Tian ◽

Hang Liu ◽

...

Keyword(s):

Relative Humidity ◽

Synergistic Effect ◽

Morphological Changes ◽

Aerosol Particles ◽

Water Soluble ◽

Effect Of Water ◽

Supplementary Material ◽

Soluble Species ◽

Pollution Episodes

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Molecular Distributions of Soluble Oxidation Products from Coals Characterized by Mass Spectrometers

International Journal of Analytical Chemistry ◽

10.1155/2018/5174172 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

Xing Fan ◽

Fei Wang

Keyword(s):

Mass Spectrometry ◽

Direct Analysis ◽

Water Soluble ◽

Oxidation Products ◽

Gas Chromatography Mass Spectrometry ◽

Mass Spectrometers ◽

Polycarboxylic Acids ◽

Alkanoic Acids ◽

Carboxylic Groups ◽

Soluble Species

Oxidation of three coals with rank from lignite to anthracite in NaOCl aqueous solution was investigated in this study. The oxidation products were characterized by using gas chromatography/mass spectrometry and direct analysis in real-time mass spectrometry. The results showed that most of organic compounds in coals were converted into water-soluble species under mild conditions, even the anthracite. Benzene polycarboxylic acids (BPCAs) and chloro-substituted alkanoic acids (CSAAs) were major products from the reactions. The products from lower rank coals consist of considerable CSAAs and most products from high rank coals are BPCAs. As coal rank increases, the yield of BPCAs with more carboxylic groups increases.

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Sub- and Supercritical Water Liquefaction of Kraft Lignin and Black Liquor Derived Lignin

Energies ◽

10.3390/en13133309 ◽

2020 ◽

Vol 13 (13) ◽

pp. 3309 ◽

Cited By ~ 3

Author(s):

Jukka Lappalainen ◽

David Baudouin ◽

Ursel Hornung ◽

Julia Schuler ◽

Kristian Melin ◽

...

Keyword(s):

Supercritical Water ◽

Renewable Energy Sources ◽

Black Liquor ◽

Hydrothermal Liquefaction ◽

Water Soluble ◽

Gaseous Products ◽

Bio Oil ◽

Water Conditions ◽

Oil Water ◽

Alkali Salts

To mitigate global warming, humankind has been forced to develop new efficient energy solutions based on renewable energy sources. Hydrothermal liquefaction (HTL) is a promising technology that can efficiently produce bio-oil from several biomass sources. The HTL process uses sub- or supercritical water for producing bio-oil, water-soluble organics, gaseous products and char. Black liquor mainly contains cooking chemicals (mainly alkali salts) lignin and the hemicellulose parts of the wood chips used for cellulose digestion. This review explores the effects of different process parameters, solvents and catalysts for the HTL of black liquor or black liquor-derived lignin. Using short residence times under near- or supercritical water conditions may improve both the quality and the quantity of the bio-oil yield. The quality and yield of bio-oil can be further improved by using solvents (e.g., phenol) and catalysts (e.g., alkali salts, zirconia). However, the solubility of alkali salts present in black liquor can lead to clogging problem in the HTL reactor and process tubes when approaching supercritical water conditions.

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Synergistic effect of water-soluble species and relative humidity on morphological changes in aerosol particles in the Beijing megacity during severe pollution episodes

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-219-2019 ◽

2019 ◽

Vol 19 (1) ◽

pp. 219-232 ◽

Cited By ~ 12

Author(s):

Xiaole Pan ◽

Baozhu Ge ◽

Zhe Wang ◽

Yu Tian ◽

Hang Liu ◽

...

Keyword(s):

Relative Humidity ◽

Synergistic Effect ◽

Mineral Dust ◽

Water Soluble ◽

Dust Particles ◽

Urban Site ◽

Chemical Compositions ◽

Aerodynamic Diameter ◽

Soluble Species ◽

Pollution Episodes

Abstract. Depolarization ratio (δ) of backscattered light is an applicable parameter for distinguishing the sphericity of particles in real time, which has been widely adopted by ground-based lidar observation systems. In this study, δ values of particles and chemical compositions in both PM2.5 (aerodynamic diameter less than 2.5 µm) and PM10 (aerodynamic diameter less than 10 µm) were concurrently measured on the basis of a bench-top optical particle counter with a polarization detection module (POPC) and a continuous dichotomous aerosol chemical speciation analyzer (ACSA-14) from November 2016 to February 2017 at an urban site in Beijing megacity. In general, measured δ values depended on both size and sphericity of the particles. During the observation period, mass concentrations of NO3- in PM2.5 (fNO3) were about an order of magnitude higher than that in PM2.5−10 (cNO3) with a mean fNO3∕cNO3 ratio of 14±10. A relatively low fNO3∕cNO3 ratio (∼5) was also observed under higher relative humidity conditions, mostly due to heterogeneous processes and particles in the coarse mode. We found that δ values of ambient particles in both PM2.5 and PM2.5−10 obviously decreased as mass concentration of water-soluble species increased at unfavorable meteorological conditions. This indicated that the morphology of particles was changed as a result of water-absorbing processes. The particles with optical size (Dp) of Dp = 5 µm were used to represent mineral dust particles, and its δ values (δDp=5) decreased by 50 % as the mass fraction of cNO3 increased from 2 % to 8 % and ambient relative humidity increased up to 80 %, suggesting that mineral dust particles were likely to be spherical during humid pollution episodes. During the observation, relative humidity inside the POPC measuring chamber was stable at 34±2 %, lower than the ambient condition. Its influence on the morphology was estimated to be limited and did not change our major conclusion. This study highlights the evident alteration of non-sphericity of mineral dust particles during their transport owing to a synergistic effect of both pollutant coatings and hygroscopic processes, which plays an important role in the evaluation of its environmental effect.

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Chemical composition of aerosol particles from direct emissions of vegetation fires in the Amazon Basin: water-soluble species and trace elements

Atmospheric Environment ◽

10.1016/s1352-2310(99)00329-5 ◽

2000 ◽

Vol 34 (10) ◽

pp. 1641-1653 ◽

Cited By ~ 256

Author(s):

Márcia A Yamasoe ◽

Paulo Artaxo ◽

Antonio H Miguel ◽

Andrew G Allen

Keyword(s):

Trace Elements ◽

Chemical Composition ◽

Amazon Basin ◽

Aerosol Particles ◽

Water Soluble ◽

Vegetation Fires ◽

Basin Water ◽

Soluble Species

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Synergistic effect of water-soluble species and relative humidity on morphological changes of aerosol particles in Beijing mega-city during severe pollution episodes

10.5194/acp-2018-623 ◽

2018 ◽

Author(s):

Xiaole Pan ◽

Baozhu Ge ◽

Zhe Wang ◽

Yu Tian ◽

Hang Liu ◽

...

Keyword(s):

Relative Humidity ◽

Synergistic Effect ◽

Mass Fraction ◽

Mass Concentration ◽

Morphological Changes ◽

Aerosol Particles ◽

Water Soluble ◽

Coarse Mode ◽

Heavy Pollution ◽

Soluble Species

Abstract. Depolarization ratio (δ) of backscattered light from aerosol particle is an applicable parameter for real-time distinguishing spherical and non-spherical particles, which has been widely adopted by ground-based Lidar observation and satellite remote sensing. From November 2016 to February of 2017, it consecutively suffered from numbers of severe air pollution at Beijing with daily averaged mass concentration of PM2.5 (aerodynamic diameter less than 2.5 μm) larger than 150 μg/m3. We preformed concurrent measurements of water-soluble chemical species and depolarization properties of aerosol particles on the basis of a continuous dichotomous Aerosol Chemical Speciation Analyzer (ACSA-14) and a bench-top optical particle counter with a polarization detection module (POPC). We found that δ value of ambient particles generally decrease as mass concentration of PM2.5 increased at unfavorable meteorological condition. Ratio of mass concentration of nitrate (NO3−) to that of sulfate (SO42−) in PM2.5 was 1.5 ± 0.6, indicating of great importance of NOx in the formation of heavy pollution. Mass concentration of NO3− in PM2.5 (fNO3) was generally an order of magnitude higher than that in coarse mode (cNO3) with a mean fNO3 / cNO3 ratio of 14 ± 10. Relatively high allocation (fNO3/cNO3 = 5) of NO3− in coarse mode could be partially attributed to hygroscopic growth/coagulation of nitrate-rich fine mode particles under higher relative humidity condition. As a result, δ values of particles with Dp = 2 μm (δDp = 2) and 5 μm (δDp = 5) decreased evidently as the mass fraction of water-soluble species (NO3− and SO42−) increase in both PM2.5 and PM2.5–10, respectively. In particular, due to synergistic effect of RH, δDp = 5 value could decrease by 50 % as mass fraction of NO3− in PM2.5–10 increased from 8 % to 23 %. It suggested that alteration of non-sphericity of mineral dust particles was evident owing to coating with pollutants and heterogeneous reactions on the surface of the particle during heavy pollution period. This study brings the attention to great variability of morphological changes of aerosol particles along the transport, which have great complex effects in evaluating their climate and health effect.

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