pH 空気-水界面におけるH2O2の自発的形成に影響する
Maria Angelaki1, Jill d'Erceville1, D James Donaldson2,3
1Universite Claude Bernard Lyon 1, CNRS, IRCELYON, UMR 5256, Villeurbanne, F-69100, France.
Journal of the American Chemical Society
|September 16, 2024
まとめ
微小粒子の空気と水の界面での過酸化水素 (H2O2) 形成は酸性に影響する. アルカリ条件と溶けたCO2はH2O2生成に影響し,ブロミドイオンはpHに依存しない.
科学分野:
- 大気化学
- 環境科学
- 物理化学
背景:
- マイクロドロップルの空気と水のインターフェースは,ヒドロキシル基 (OH) や過酸化水素 (H2O2) のような大気中の酸化物質の重要な源です.
- ドロップレットサイズ,塩分濃度,有機成分などの要因は酸化物質の形成に影響しますが,酸性の役割についてはさらなる調査が必要です.
研究 の 目的:
- 塩を含有する水性マイクロドロップレットにおける自発的な表面間過酸化水素の形成に対する酸性の影響を調査する.
- 溶けた二酸化炭素とpHが,空気と水の界面でのH2O2生成にどのように影響するかを理解する.
主な方法:
- 硫酸ナトリウム (Na2SO4),塩化ナトリウム (NaCl),および塩化ナトリウム (NaBr) の溶液を4から9.5のpH範囲で霧化する.
- 超高純度のN2/O2ガスを使って,制御された温度 (292 ± 1 K) と湿度 (90 ± 2%) の下で微小粒子の収集とH2O2濃度の測定.
- H2O2形成への影響を評価するために,CO2を浴ガスに添加する.
主要な成果:
- Na2SO4とNaClの水滴はアルカリ状態では約40%増加し,OH−の生成を促すことを示している.
- 溶けたCO2の存在は,より高いpHでより低いH2O2レベルをもたらし,CO2がインターフェイスH2O2生成を妨害することを示唆しています.
- NaBr滴のH2O2形成は,pHまたはバットガスに依存せず,電子源としてのBr-の役割を強調しました.
結論:
- 酸度がH2O2の形成に大きく影響し,アルカリの条件は硫酸塩と塩化物滴の生成を好む.
- 溶けたCO2は,OH基と電子と反応することで,H2O2の形成を抑制することができる.
- ブロミドイオンは効率的なインターフェイス電子源として作用し,pHとバスのガス組成からH2O2の形成を切り離します.
さらに関連する動画
06:39Author Spotlight: Design and Evaluation of Au-Electroplated Carbon Fiber Cloth Electrodes for Hydrogen Peroxide Fuel Cells
Published on: October 20, 2023
2.7K
10:01Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
Published on: December 4, 2017
12.2K
関連する概念動画
Mixtures of Acids
662
The pH of a solution containing an acid can be determined using its acid dissociation constant and initial concentration. If a solution contains two different acids, then its pH can be determined using one of several methods depending on the relative strength of the acids and their dissociation constants.
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
662
Acid–Base Equilibria: Activity-Based Definition of pH
563
For an ideal solution, the pH is defined as the negative logarithm of the hydrogen ion concentration. For a non-ideal solution, an accurate measurement of the pH must consider the negative logarithm of the hydrogen ion activity rather than concentration. In such a solution, the pH can be more accurately defined as the negative logarithm of a product of the hydrogen ion concentration and its activity coefficient.
In solutions of very low ionic strength—for example, pure water—the...
In solutions of very low ionic strength—for example, pure water—the...
563
Polyprotic Acids
29.1K
Acids are classified by the number of protons per molecule that they can give up in a reaction. Acids such as HCl, HNO3, and HCN that contain one ionizable hydrogen atom in each molecule are called monoprotic acids. Their reactions with water are:
29.1K
Water: A Bronsted-Lowry Acid and Base
50.2K
The reaction between a Brønsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:
50.2K
Acid-Catalyzed Hydration of Alkenes
13.8K
Alkenes react with water in the presence of an acid to form an alcohol. In the absence of acid, hydration of alkenes does not occur at a significant rate, and the acid is not consumed in the reaction. Therefore, alkene hydration is an acid-catalyzed reaction.
13.8K
pH Scale
68.5K
Hydronium and hydroxide ions are present both in pure water and in all aqueous solutions, and their concentrations are inversely proportional as determined by the ion product of water (Kw). The concentrations of these ions in a solution are often critical determinants of the solution’s properties and the chemical behaviors of its other solutes. Two different solutions can differ in their hydronium or hydroxide ion concentrations by a million, billion, or even trillion times. A common means of...
68.5K
