Synthetic water-soluble polymeric materials are widely employed in e.g. cleaning detergents, personal care products, paints or textiles. Accordingly, these compounds reach sewage treatment plants and may enter receiving waters and the aquatic environment. Characteristically, these molecules show a polydisperse molecular weight distribution, comprising multiple repeating units, i.e. a homologous series (HS). Their analysis in environmentally relevant samples has received some attention over the last two decades, however, the majority of previous studies focused on surfactants and a molecular weight range <1000 Da. To capture a wider range on the mass versus polarity plane and extend towards less polar contaminants, a workflow was established using three different ionization strategies, namely conventional electrospray ionization, atmospheric pressure photoionization and atmospheric pressure chemical ionization. The data evaluation consisted of suspect screening of ca. 1200 suspect entries and a non-target screening of HS with pre-defined accurate mass differences using ca. 400 molecular formulas of repeating units of HS as input and repeating retention time shifts as HS indicator. To study the fate of these water-soluble polymeric substances in the wastewater treatment process, the different stages, i.e. after primary and secondary clarifier, and after ozonation followed by sand filtration, were sampled at a Swiss wastewater treatment plant. Remaining with two different ionization interfaces, ESI and APPI, in both polarities, a non-targeted screening approach led to a total number of 146 HS (each with a minimum number of 4 members), with a molecular mass of up to 1200 detected in the final effluent. Of the 146 HS, ca 15% could be associated with suspect hits and approximately 25% with transformation products of suspects. Tentative characterization or probable chemical structure could be assigned to almost half of the findings. In positive ionization mode various sugar derivatives with differing side chains, for negative mode structures with sulfonic acids, could be characterized. The number of detected HS decreased significantly over the three treatment stages. For HS detectable also in the biological and oxidative treatment stages, a change in HS distribution towards to lower mass range was often observed.

Evaluation of surfactants as steam diverters/mobility control agents in light oil steamfloods: Effect of oil composition, rates and experimental conditions.

The polarizing microscope was used to study the structure of aqueous solutions of petroleum sulfonates in the composition range planned for injection. All the surfactants studied showed a basic pattern of transformation between one structure and another over a relatively narrow range of salinities. As the salinity where this transformation occurs increases, so does the optimum salinity with a given oil, the condition of lowest interfacial tension. A polarized light box is being: developed to permit rapid determination of solution structure without the microscope since information on structure may be useful in the early stages -0f surfactant selection. Solutions containing a well-characterized surfactant, sodium dodecyl sulfate, were found to have the same basic structure pattern as the sulfonates. Hence, further experiments with this simple material should provide information relevant to the more complex petroleum sulfonates. The microscope was used to observe the dynamic contacting process between a surfactant solution and oil. Equilibration proceeds more rapidly at high salinities, mainly because of the spontaneous emulsification which occurs under these conditions. The ultracentrifuge was used to study microemulsions containing a conventional petroleum sulfonate. Results were similar to previous results for synthetic sulfonates except in a region where interfacial tension and solubilization results for the conventional sulfonate were anomalous. Progress was made in development of a theory to predict drop size in microemulsions, an important property influencing both phase behavior and interfacial tension.