Hans Oskarsson - Academia.edu (original) (raw)

Papers by Hans Oskarsson

Journal of the American Chemical Society, 2003

All Days, Feb 5, 2003

Insulated and heated pipe bundles are frequently used in sub sea oil production systems to avoid ... more Insulated and heated pipe bundles are frequently used in sub sea oil production systems to avoid low oil temperatures. To boost the heating capacity of the 10 km long pipe bundle from the Gullfaks South field in the North Sea, a surfactant based DRA was developed. The DRA was injected in the 20 km long heating medium loop in July 2001, and after over 12 months of operation the DRA gives over 50 % increase in the heating medium flow rate. The surfactant has effectively reduced the pressure drop in the heating medium circulation loop resulting in an increase in the flow rate and in the bundle heating capacity.

All Days, 2003

The Canadian Journal of Chemical Engineering, 2022

Anti-Corrosion Methods and Materials, 2011

PurposeThe paper reports an investigation into the use of aqueous extracts of rice bran as a gree... more PurposeThe paper reports an investigation into the use of aqueous extracts of rice bran as a green inhibitor for corrosion of carbon steel in hydrochloric acid (HCl) solution.Design/methodology/approachExtracts from the rice bran were used as the main component of an environmentally friendly corrosion inhibitor for use in HCl pickling processes. Inhibition behavior on carbon steel in HCl was investigated by means of mass‐loss tests, polarization curves, electrochemical impedance spectroscopy and atomic force microscopy.FindingsThe results show that the extract exhibited good inhibition performance in 1 M HCl. The inhibition efficiency increased with increase in the concentration of the inhibitor and was only moderately affected by temperature variations in the range 303‐363 K. The inhibitive action was due to adsorption on the A3 steel and the adsorption process was consistent with the Langmuir isotherm. The free energy of adsorption (ΔGads.) was −4.192 kJ/mol. The negative value of...

Proceedings of SPE International Symposium on Oilfield Chemistry, 2005

Gas hydrate inhibitors have been evaluated using different techniques in the past.In particular, ... more Gas hydrate inhibitors have been evaluated using different techniques in the past.In particular, anti-agglomerates have been evaluated in Rocking Cells, Stirred Autoclaves, different types of pipe flow devices such as the rotating wheel device, and regular pipe rheology.In this paper the development of new anti-agglomerate chemistry is illustrated using a new technique where miniature autoclaves, that allow for the simultaneous testing of up to 47 samples in an affordable way, are used.Temperature and turbidity are measured directly, whereas the viscosity of the mixture is indirectly measured via a unique rotating stirring device.

SPE International Symposium on Oilfield Chemistry, 2005

In many cases it is desirable to increase the flow of injection water when an oil well deteriorat... more In many cases it is desirable to increase the flow of injection water when an oil well deteriorates. It is very costly in offshore operation to lay down an additional water pipe to the injection site. Flow improvers for the injection water will thus be the most cost-effective way to increase the flow rate. During the last years water-soluble polymers have also been applied for this purpose. These drag-reducing polymers are however only slowly biodegraded which has been an incentive for the development of readily biodegradable surfactants as flow improvers for injection water. A combination of a zwitterionic and an anionic surfactant has been tested in a 5.5 inch, 700 m long flow loop containing sulphate brine with salinity similar to sea water. A drag reduction between 75 and 80% was achieved with 200 ppm of the surfactant blend at an average velocity of 1.9 m/s and between 50 and 55% at 2.9 m/s. Due to the self-healing properties of the drag-reducing structures formed by surfactant...

Faraday Discussions, 2022

XPS spectra demonstrate that the chemistry of well-inhibited carbon steel interfaces, formed thro... more XPS spectra demonstrate that the chemistry of well-inhibited carbon steel interfaces, formed through sorption of organic surface-actives, is acid dependent.

Journal of Surfactants and Detergents, 2019

An optimized one-pot recipe has been developed to synthesize a surfactant molecule, referred to a... more An optimized one-pot recipe has been developed to synthesize a surfactant molecule, referred to as OMID, consisting of an imidazoline head group and aliphatic tail, which is an exemplar corrosion inhibitor for carbon steel in acidic solutions. As evidenced by gas chromatography, 1 H and 13 C nuclear magnetic resonance, and Fourier-transform infrared data, a high-purity product was achieved without the use of either a solvent or catalyst. Critical micelle concentration values and corrosion inhibition efficiencies (η%) were determined in aqueous solutions of hydrochloric acid and sulfuric acid using surface tensiometry and linear polarization resistance measurements, respectively. Hydrolysis of the imidazoline head group as a function of pH (0-11) was explored with ultraviolet-visible absorption spectroscopy. In addition, N 1s and C 1s X-ray photoelectron spectroscopy data were acquired from both surface-adsorbed OMID and a multilayer of the imidazoline head group of OMID. These latter data are highly relevant to those attempting to understand OMID inhibition chemistry.

Journal of Surfactants and Detergents, 2007

N,N-di(3-aminopropyl)dodecylamine (C12-Y-amine), N-dodecyl-N,N-di[(3-D-gluconylamido)propyl] amin... more N,N-di(3-aminopropyl)dodecylamine (C12-Y-amine), N-dodecyl-N,N-di[(3-D-gluconylamido)propyl] amine (C12-DGA), N-dodecyl-N,N-bis[(3-lactobionylamido)propyl]amine (C12-DLA), N-dodecyl-N-[(3-lactobionylamido)propyl]amine (C12-LA), and ethoxylated N,N-di(3-aminopropyl)dodecylamine [C12-Y-amine with 4 and 8 ethylene oxide (EO)] have been synthesized, and their physical-chemical properties have been studied. Adsorption was measured at the air-water interface by the du Noü y ring method and at solid surfaces consisting of self-assembled monolayers (SAMs) of alkanethiols on gold using surface plasmon resonance. Results from surface tension measurements showed that adsorption at the air-water interface is pH dependent. At low pH, reduction in surface tension is less pronounced as a result of protonation of the amino groups of the surfactants. At the SAM model surfaces, generated by adsorption of alkanethiols or mixtures of alkanethiols on gold presenting methyl, hydroxyl, and carboxyl groups, the highest amount of adsorbed surfactant was obtained on a surface composed of a mixture of methyl and carboxyl groups. In general, the sugar-derived surfactants, DGA, DLA, and LA, adsorbed less than the ethoxylates. Surfactant biodegradation was investigated by the closed bottle test. Only C12-Y-amine was found to be readily biodegradable. However, the polyol surfactants were more biodegradable than the ethoxylates.

Journal of Colloid and Interface Science, 2006

Adsorption of a series of ethoxylated cationic surfactants at model surfaces of alkanethiol self-... more Adsorption of a series of ethoxylated cationic surfactants at model surfaces of alkanethiol self-assembled monolayers was studied by the surface plasmon resonance technique. Model surfaces were tailor-made by choosing alkanethiols or mixtures of alkanethiols with methyl, hydroxyl, carboxyl, and trimethylammonium groups in terminal position. The ethoxylated and quaternized cationic surfactants having from 2 to 18 oxyethylene units, showed a decrease in adsorbed amount with increasing oxyethylene chain length for both hydrophobic and hydrophilic surfaces. On a negatively charged surface, containing carboxylate groups, the surfactant with only two oxyethylene groups adsorbed strongly due to electrostatic attraction and the adsorption increased with increasing amount of surface carboxylate groups. This work shows the usefulness of self-assembled alkanethiols on gold as a tool for performing surfactant adsorption studies on surfaces with variable hydrophobicity and charge.

Journal of Colloid and Interface Science, 2005

The force-distance curves of 12-2-12 and 12-4-12 Gemini quaternary ammonium bromide surfactants o... more The force-distance curves of 12-2-12 and 12-4-12 Gemini quaternary ammonium bromide surfactants on mica and silica surfaces obtained by atomic force microscopy (AFM) were correlated with the structure of the adsorption layer. The critical micelle concentration was measured in the presence or absence of electrolyte. The electrolyte effect (the decrease of CMC) is significantly more pronounced for Gemini than for single-chain surfactants. The maximum compressive force, F max , of the adsorbed surfactant aggregates was determined. On the mica surface in the presence of 0.1 M NaCl, the Gemini micelles and strong repulsive barrier appear at surfactant concentrations 0.02-0.05 mM, which is significantly lower than that for the single C 12 TAB (5-10 mM). This difference between single and Gemini surfactants can be explained by a stronger adsorption energy of Gemini surfactants. The low concentration of Gemini at which this surfactant forms the strong micellar layer on the solid/solution interface proves that Gemini aggregates (micelles) potentially act as dispersing agent in processes such as chemical mechanical polishing or collector in flotation. The AFM force-distance results obtained for the Gemini surfactants were used along with turbidity measurements to determine how adsorption of Gemini surfactants affects dispersion stability. It has been shown that Gemini (or two-chain) surfactants are more effective dispersing agents, and that in the presence of electrolyte, the silica dispersion stability at pH 4.0 can also be achieved at very low surfactant concentrations (∼0.02 mM).

Journal of Colloid and Interface Science, 2012

The micellar aggregation number of a series of ester-containing gemini surfactants has been deter... more The micellar aggregation number of a series of ester-containing gemini surfactants has been determined with steady state and with time-resolved fluorescence quenching. The latter method gave values of aggregation number about twice those obtained with the former method. It was found that the length of the spacer was the most important factor affecting the aggregation number. The length and the nature of the surfactant alkyl chains were of less importance in spite of the fact that the length of the alkyl chains strongly affects the solution properties of the unimers.