engleski

Study of surfactants in aerosols from urban area of Zagreb: Electrochemical approach

Aerosols are important atmospheric constituents due to of their impact on air quality and also because of their role in inducing climate change. Organic particles are either emitted directly into the atmosphere by fossil fuel or biomass combustion thus forming primary organic aerosols or are formed from gaseous precursors leading to secondary organic aerosols.The most reactive sub-fraction of the organic material in atmospheric aerosols is surface active, arranging itself into organic films at the gas-aerosol interface. These films of surface active substances (SAS) or surfactants can inhibit trace gas uptake, affecting atmospheric chemistry and composition, and they can also impact water uptake, influencing cloud formation properties. Additionally, these films can depress surface tension of atmospheric aerosols, leading to enhanced cloud nuclei. The current situation of the research in atmospheric chemistry is reflected by the lack of a sensitive method for direct analysis of complex mixture of atmospheric water soluble SAS. The electrochemical methods offer an elegant way of SAS qualitative and quantitativ characterization based on the measuring of electrode double layer capacity changes at mercury electrode surface. For determination of SAS with alternating current voltammetry, the change of capacity current is measured at selected potential and calibrated by model surfactant substance. The comparison of adsorption characteristics obtained for natural aerosol samples with those of different model substances as well as with those of naturally isolated humus-like material will be analyzed with the aim to better understand the nature of dominant aerosol SAS fraction. Adsorption behaviour of surfactant organics and the structure of SAS adsorbed layer at the electrode surface will be obtained by the investigation of their influence on the electrode processes of other ions used as electrochemical tools. The lead and cadmium ions are chosen as suitable due to their convenient electrochemical response. The method will be applied for study of surfactant properties in aerosols collected during 2011-2012 in urban area of Zagreb.

aerosols; surfactants; organic matter; electrochemistry

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