Sulfur Chemistry at the Air-Water Interface
Pai Liu1,2, Qishen Huang2, Ting Lei1
1State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;
Annual Review of Physical Chemistry
|November 12, 2025
Summary
Sulfate aerosol formation, a key air pollutant, primarily occurs at aerosol surfaces, not in cloud water. This review explores the faster interfacial reactions and new methods to study them.
Area of Science:
- Atmospheric Chemistry
- Environmental Science
- Chemical Kinetics
Background:
- Sulfur dioxide (SO2) oxidation to sulfate aerosols drives urban air pollution.
- Traditionally, this conversion was thought to occur mainly in cloud and fog droplets.
- Recent research indicates heterogeneous conversion at aerosol surfaces is dominant in urban environments.
Purpose of the Study:
- To review advances in understanding heterogeneous SO2 conversion at aerosol surfaces.
- To explain the accelerated S(IV) oxidation at the air-water interface.
- To present methods for determining reaction location and surface kinetics.
Main Methods:
- Analysis of scaling relationships in apparent reaction kinetics to pinpoint reaction location.
- Utilizing multiscale models to predict or retrieve localized surface reaction kinetics.
- Review of experimental techniques for studying interfacial reactions.
Main Results:
- S(IV) oxidation is significantly faster at the air-water interface compared to bulk aqueous phase.
- Experimental approaches using kinetic scaling relationships can identify the reaction's location.
- Multiscale modeling provides a pathway to quantify surface reaction rates.
Conclusions:
- Heterogeneous SO2 conversion at aerosol surfaces is a critical pathway for sulfate aerosol formation in urban air.
- The air-water interface plays a crucial role in atmospheric sulfur chemistry.
- Further research is needed to address open questions regarding interfacial processes.
Related Concept Videos
01:22The Sulfur Cycle
51.7K
Sulfur, an important element in the chemical makeup of proteins, is recycled through the atmosphere and aquatic and terrestrial environments. Found in the atmosphere as sulfur dioxide (SO2), sulfur is released by decaying organisms, weathered rocks, geothermal vents, volcanos, and burning fossil fuels. It is deposited into the ecosystem, cycled through the biotic community, and either released back into the atmosphere as gas or deposited in marine sediment for long-term storage and eventual...
51.7K
01:20Sulfur Assimilation
309
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to...
309
02:26Preparation and Reactions of Sulfides
5.7K
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
5.7K
01:22Electrophilic Aromatic Substitution: Sulfonation of Benzene
7.7K
Sulfonation of benzene is a reaction wherein benzene is treated with fuming sulfuric acid at room temperature to produce benzenesulfonic acid. Fuming sulfuric acid is a mixture of sulfur trioxide and concentrated sulfuric acid.
7.7K
02:33Preparation and Reactions of Thiols
7.4K
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
7.4K
02:17Structure and Nomenclature of Thiols and Sulfides
5.6K
Thiols and sulfides are sulfur analogs of alcohols and ethers, respectively, where the sulfur atom takes the place of the oxygen atom. Thus, thiols are generally represented as RSH, where R is an alkyl substituent and —SH is the functional group. On the other hand, in sulfides, the central sulfur atom is bonded to two hydrocarbon groups on either side. Depending upon the type of group, sulfides can be either symmetrical or asymmetrical. Both thiols and sulfides display a bent geometry,...
5.6K