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The type of produced crude oil emulsion is primarily determined by the physicochemical properties of the oil itself. Heavy crudes of large viscosities have tendency to form stable water-in-oil (W/O) emulsions. These emulsions can be encountered already at the exit of the well bore as a result of the shear and intense mixing occurring while bringing the oil up to the surface. In this study, we prepared...
The current work explores the effects of alternating current (AC) electric fields on coalescence of water droplets in crude oil. A North Sea crude oil emulsion with aqueous phase volume fraction of 0.3 and ∼2μm water droplets was used. The emulsions were prepared by an Ultra-Turrax disperser. Volume-specific energy input (E v ) has been calculated. Droplet collision frequency was enhanced...
This study deals with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation of cellulose. Softwood and hardwood pulp fibers were suspended in water and oxidized to various extents at pH 10 and 22 °C using sodium hypochlorite in the presence of TEMPO radical and sodium bromide. This reaction system is known to be the most efficient one for the introduction of both surface carboxyl and aldehyde...
The barrier properties of microfibrillated cellulose (MFC) films were improved by heterogeneous gas-phase esterification using various combinations of trifluoroacetic acid anhydride, acetic acid and acetic anhydride. The temperature, reagent ratio and reaction time were varied in the experimental design. The effects of two different purification procedures on the barrier properties of esterified MFC...
2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized cellulose nanofibers were prepared from two kraft pulps (Norway spruce and mixed eucalyptus) using the TEMPO/NaBr/NaClO system at pH 10 and 22 °C. After reaction and mechanical treatment, the TEMPO-oxidized celluloses were used for preparation of self-standing films and coatings of laminate films on 50-μm-thick polyethylene terephthalate...
TEMPO-oxidized cellulose nanofibers (TOCN) were obtained from commercial Norway spruce and mixed Eucalyptus cellulose pulps using TEMPO/sodium bromide (NaBr)/sodium hypochlorite (NaClO) system at pH 10 and 22 °C. After reaction, the fibrillated TEMPO-oxidized celluloses were used for preparation of self-standing films and casting of laminate films on 50 μm thick polyethylene terephthalate. Significant...
Heterogeneous acetylation of microfibrillated cellulose (MFC) was carried out to modify its physical properties and at the same time to preserve the morphology of cellulose fibrils. The overall reaction success was assessed by FTIR together with the degree of substitution (DS) defined by titration and the degree of surface substitution (DSS) evaluated by means of XPS. Dynamic contact angle measurements...
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