@article{verruto_le_kilpatrick_2009, title={Adsorption and molecular rearrangement of amphoteric species at oil-water interfaces}, volume={113}, number={42}, journal={Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces & Biophysical}, author={Verruto, V. J. and Le, R. K. and Kilpatrick, P. K.}, year={2009}, pages={13788–13799} }
 @article{verruto_kilpatrick_2008, title={Water-in-Model Oil Emulsions Studied by Small-Angle Neutron Scattering: Interfacial Film Thickness and Composition}, volume={24}, ISSN={["0743-7463"]}, DOI={10.1021/la802095m}, abstractNote={The ever-increasing worldwide demand for energy has led to the upgrading of heavy crude oil and asphaltene-rich feedstocks becoming viable refining options for the petroleum industry. Traditional problems associated with these feedstocks, particularly stable water-in-petroleum emulsions, are drawing increasing attention. Despite considerable research on the interfacial assembly of asphaltenes, resins, and naphthenic acids, much about the resulting interfacial films is not well understood. Here, we describe the use of small-angle neutron scattering (SANS) to elucidate interfacial film properties from model emulsion systems. Modeling the SANS data with both a polydisperse core/shell form factor as well as a thin sheet approximation, we have deduced the film thickness and the asphaltenic composition within the stabilizing interfacial films of water-in-model oil emulsions prepared in toluene, decalin, and 1-methylnaphthalene. Film thicknesses were found to be 100-110 A with little deviation among the three solvents. By contrast, asphaltene composition in the film varied significantly, with decalin leading to the most asphaltene-rich films (30% by volume of the film), while emulsions made in toluene and methylnaphthalene resulted in lower asphaltenic contents (12-15%). Through centrifugation and dilatational rheology, we found that trends of decreasing water resolution (i.e., increasing emulsion stability) and increasing long-time dilatational elasticity corresponded with increasing asphaltene composition in the film. In addition to the asphaltenic composition of the films, here we also deduce the film solvent and water content. Our analyses indicate that 1:1 (O/W) emulsions prepared with 3% (w/w) asphaltenes in toluene and 1 wt % NaCl aqueous solutions at pH 7 and pH 10 resulted in 80-90 A thick films, interfacial areas around 2600-3100 cm (2)/mL, and films that were roughly 25% (v/v) asphaltenic, 60-70% toluene, and 8-12% water. The increased asphaltene and water film composition at pH 10 versus pH 7, along with unique dynamic interfacial tension profiles, suggested that the protonation state of carboxylic moieties within asphaltenes impacts the final film properties. This was further supported when we characterized similar asphaltenic emulsions that also contained 9-anthracence carboxylic acid (ACA). Addition of this aromatic acid led to slightly thinner films (70-80 A) that were characteristically more aqueous (up to 20% by volume) and 5-6% (v/v) ACA. This unique in situ characterization (deduced entirely from SANS data from emulsion samples) of the entire film composition calls for further investigation regarding the role this film-based water plays in emulsion stability.}, number={22}, journal={LANGMUIR}, author={Verruto, Vincent J. and Kilpatrick, Peter K.}, year={2008}, month={Nov}, pages={12807–12822} }
 @article{yang_verruto_kilpatrick_2007, title={Dynamic asphaltene-resin exchange at the oil/water interface: Time-dependent W/O emulsion stability for asphaltene/resin model oils}, volume={21}, ISSN={["1520-5029"]}, DOI={10.1021/ef060465w}, abstractNote={The critical electric field (CEF) technique was used to determine the time-dependent stability of water-in-oil emulsions in which asphaltenes stabilize the film. Stabilizing films comprising purely...}, number={3}, journal={ENERGY & FUELS}, author={Yang, Xiaoli and Verruto, Vincent J. and Kilpatrick, Peter K.}, year={2007}, pages={1343–1349} }
 @article{verruto_kilpatrick_2007, title={Preferential solvent partitioning within asphaltenic aggregates dissolved in binary solvent mixtures}, volume={21}, ISSN={["0887-0624"]}, DOI={10.1021/ef060456n}, abstractNote={The heaviest fraction of crude oils, asphaltenes, has been shown to play a central role in the stabilization of troublesome water-in-crude oil emulsions. In previous model oil systems, emulsion stability was observed to depend notably on the properties of self-assembled interfacially active asphaltenic aggregates. Thus, careful characterization of these aggregates is of great importance for better understanding of asphaltene-stabilized emulsions. Small-angle neutron scattering (SANS) has proven to be a powerful tool for such characterization. Described here is the application of SANS on asphaltenes from Hondo crude oil dissolved in binary solvent mixtures of toluene with n-heptane, decalin, or 1-methylnaphthalene. A polydisperse oblate cylinder (POC) form factor model was used to fit the aggregate scattering data, and subsequent calculations of minimum error were performed to ascertain the entrained solvent composition within the aggregates. When toluene was paired with either a weak solvent (decalin) or a precipitant (n-heptane), the entrained solvent composition was nearly pure toluene (>90%). Conversely, for the toluene/1-methlnaphthalene pairing, methylnaphthalene demonstrated slight preferential entrainment (∼60%) compared with the bulk composition (∼57%). This is the first such in situ experimental determination of the aggregate composition for asphaltenes dissolved in binary solvents, reinforcing the important role of asphaltene−solvent interactions in asphaltene self-assembly.}, number={3}, journal={ENERGY & FUELS}, author={Verruto, Vincent J. and Kilpatrick, Peter K.}, year={2007}, pages={1217–1225} }