Characterization of silicone oil emulsions stabilized by TiO2 suspensions pre-adsorbed SDS

To study the effects of pre-adsorbed emulsifier on Pickering emulsion stability, the preparation of silicone oil emulsions by TiO₂ suspensions pre-adsorbed sodium dodecyl sulfate (SDS) at the fixed TiO₂ concentration of 0.15 g was carried out below a fiftieth of critical micelle concentration (cmc) of SDS, where all added amounts of SDS are adsorbed on the TiO₂ particles. The stability of the Pickering emulsions incorporating TiO₂ suspensions pre-adsorbed SDS was investigated by measuring the volume fraction of emulsified silicone oil, adsorbed amounts of TiO₂ suspensions pre-adsorbed SDS, oil droplet size, and some rheological responses such as the stress-strain sweep curve and strain and frequency dependences of dynamic viscoelastic moduli. The silicone oil was almost emulsified by TiO₂ suspensions pre-adsorbed SDS above cmc/10³. Increasing in the adsorbed amount of SDS on the TiO₂ particles leads to an increase in the adsorbed amounts of TiO₂ suspensions pre-adsorbed SDS. Such silicone oil emulsions for the first time showed two yield stresses in the stress-strain sweep curve as well as the oscillatory stress-strain curve. The respective yield stresses also increase with an increase in the adsorbed amounts of TiO₂ suspensions pre-adsorbed SDS. From such characteristic rheological properties and a partial sedimentation of some TiO₂ particles remained in the dispersion medium, we proposed the formation of a three dimensional network of the flocculated TiO₂ particles pre-adsorbed SDS on the silicone oil droplets.     

Effect of process parameters and methylcellulose supplementation on the properties of n-undecane emulsions

Study was made on the influence of processing parameters on droplet size during emulsification with an Ultra-Turrax homogenizer. Emulsions of undecane in water, stabilized with nonionic Igepals, were prepared at the optimum hydrophilic-lipophilic balance (HLB) of 11.5 and oil-to-water (O/W) ratio of 5/95; the sizes of emulsion droplets were measured at intervals from the commencement of emulsification. Results showed that the optimum emulsification conditions, as pertaining to minimum particle size, arose at 13 400 rpm and 20 minutes of Ultra-Turrax treatment. Additionally, effects exerted by the presence of methylcellulose, time and storage temperature on the emulsions were determined. Emulsions prepared at the optimal processing parameters revealed that the smallest particle sizes (lower than 200 nm) and the best emulsion stability were demonstrated at the oil/water ratios of 3/97 and 5/95, with 3% surfactant content, an HLB value of 10 to 11 and the storage temperature of 25°C, irrespective of the content of methylcellulose.     

Interactions and partitioning of diluents/plasticizers in hydroxypropyl methylcellulose and polyvinyl alcohol homopolymers and blends. Part II: Glycerol

The interactions and partitioning of glycerol in polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC) and their blends has been studied by means of torsional braid analysis (TBA). Glycerol was shown to be a more efficient plasticizer for PVA than HPMC in agreement with solubility parameter prediction. Kelley-Bueche-type equations were fitted to the experimentalTg data and initial slopes yielded an interaction parameter,Kø, between glycerol and the two polymers. Incorporation of glycerol in PVA/HPMC blends did not alter the incompatibility of the two polymers and plasticized both phases. The compositions of the two plasticized phases were calculated from Kelley-Bueche expressions fitted to the experimental data, enabling determination of the glycerol partition coefficients into the two phases. In blends with 20–60% PVA, glycerol partitioned selectively into the PVA-rich phase whereas in the system with 80% PVA, glycerol partitioned selectively into the HPMC-rich inclusions.     

Interactions and partitioning of diluents/plasticizers in hydroxypropyl methylcellulose and polyvinyl alcohol homopolymers and blends. Part III: Polyethylene glycol 400

The interactions and partitioning of polyethylene glycol 400 (PEG400) in hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA) and their blends have been investigated by means of torsional braid analysis (TBA). PEG400 was shown to be a better plasticizer for HPMC than PVA, in agreement with solubility parameter predictions. Incorporation of PEG400 in blends of PVA and HPMC did not alter the incompatibility between the two homopolymers and plasticized both phases. The PEG400 content in the two phases was calculated by fitting Kelley-Bueche and quadratic expressions to the experimental data, enabling determination of the PEG400 partition coefficient. The data showed a selective partitioning of PEG400 in the HPMC phase for plasticizer contents less than 20% w/w. At higher concentrations, PEG400 continued to partition selectively into the HPMC phase for blends with 60 and 80% PVA but started partitioning in the PVA phase for blends with 20 and 40% PVA.     

Interactions and partitioning of diluents/plasticizers in hydroxypropyl methylcellulose and polyvinyl alcohol homopolymers and blends. Part I: Diethylene glycol

The interactions and partitioning of diethylene glycol (DEG) in polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC) and their blends has been studied. DEG acted as efficient plasticizer for both homopolymers, lowering theirT _g and relative rigidity. Kelly-Bueche-type equations were fitted successfully to the experimental data and yielded an interaction parameter,K , between DEG and each polymer. Incorporation of DEG into two-phase blends of PVA and HPMC with 40, 50 and 60% PVA did not change the significant incompatibility of the two components and plasticized both phases. Composition calculations based on Kelley-Bueche-type expressions fitted to the experimental data afforded determination of the partition coefficients of DEG into the two phases of the blends. In the case of the 5050 weight% system, it partitioned almost equally into both phases. The results are discussed in terms of the DEG affinity to interact with the two polymers by means of the dispersive, polar and hydrogen-bonding contribution to the solubility parameters.     

Effect of dimethylaminoethyl methacrylate on the graft copolymerization of ethyl acrylate onto hydroxypropyl methylcellulose in aqueous medium

Graft copolymerization of an ethyl acrylate (EA) and dimethylaminoethyl methacrylate (DMAEMA) monomer mixture onto water-soluble hydroxypropyl methylcellulose was investigated with potassium persulfate (KPS) as the initiator in an aqueous medium. The effects of introducing DMAEMA onto the graft copolymerization and the properties of the resulting latex that was produced were studied systematically. The optimum conditions for the graft copolymerization in terms of percentage of grafting and grafting efficiency were determined. The graft copolymer was characterized by Fourier transform infrared spectra, elemental analyses, nuclear magnetic resonance, transmission electron microscopy, and dynamic light scattering methods. The results suggest that the introduction of the DMAEMA monomer clearly accelerates the initial rate of the graft copolymerization, whereas the grafting parameters decrease significantly with increasing amounts of DMAEMA. These results can be attributed to the relatively large size of the DMAEMA molecule, its redox reaction with KPS, its hydrophilicity in water, and its chain transfer effect. The equilibrium humidity adsorption behavior and acid solubility of graft the copolymer films were also studied.     

Alkalimetric determination of hydrophobic pharmaceuticals using stabilized o/w emulsions

Protolytic properties of (+)-(S)-2-(6-methoxynaphthalen-2-yl)propanoic acid (naproxen), 2-(3-benzoylphenyl)propionic acid (ketoprofen), 4-chloro-N-(2-furylmethyl)-5-sulfamoylanthranilic acid (furosemide), and N-(2,3-dimethylphenyl)anthranilic acid (mefenamic acid) in “oil-in-water” emulsions stabilized by surfactants were studied. The procedures for alkalimetric determination of naproxen, ketoprofen, furosemide, and mefenamic acid in emulsion media with indication of the equivalence point pH-metrically and with the use of indicators were proposed.     

Silicone-protein surfactants; stability of water-in-silicone oil emulsions

Small scale water-in-silicone oil emulsions were readily prepared using high speed mixers. Two surfactant systems were studied: a comb-type silicone-polyether surfactant, and a surfactant system employing a mixture of the surface active protein human serum albumin (HSA, in the internal phase) and an alkoxysilane-modified silicone TES-PDMS in the silicone oil (continuous phase). Little difference in particle sizes was noted between the two surfactant types for a given mixing protocol, but dual-blade turbulent mixing led to relatively monodisperse particles of approximately 2–5 m in diameter while high speed Dremel mixers led to bimodal particle distributions. Prior to spontaneous demulsification of the latter emulsions stabilized by HSA/TES-PDMS (the 3225C emulsions remain stable), they proved very difficult to break. The addition of dibutyltin dilaurate to the HSA/TES-PDMS-stabilized emulsions led to catastrophic collapse of the emulsion and formation of a silicone elastomer at the bulk water/oil interface. This makes unlikely the possibility that silicone elastomers, formed by protein-catalyzed crosslinking of the alkoxysilane in albumin/TES-PDMS-stabilized emulsions, are involved in stabilizing the emulsion. The nature of the stabilization of the interface is discussed.     

Effect of emulsifier HLB and stabilizer addition on the physical stability of thyme essential oil emulsions

The objective of this work was to formulate and to further improve the stability of emulsions based on thyme essential oil. Several nonionic surfactants of different nature and with different hydrophilic?lipophilic balance (HLB) values were investigated. The surfactant with optimal HLB found for the thyme essential oil was Appyclean 6548 (HLB: 9-9.5). Afterwards, stabilizing biopolymers were added in order to improve emulsion stability. Properties of emulsions were evaluated in terms of droplet size and physical stability. Thyme essential oil/W emulsions formulated with a new biodegradable emulsifier (alkyl polypentoside) and welan gum as stabilizer were obtained with high shelf-life.     

Combined effect of hydroxypropyl methylcellulose and hydroxypropyl-β-cyclodextrin on physicochemical and dissolution properties of celecoxib

Investigation on the influence of hydroxypropyl methylcellulose (HPMC) on solubility and dissolution properties of celecoxib/hydroxypropyl-β-cyclodextrin system was carried out, with the ultimate goal of enhancing the drug bioavailability. ¹H-NMR and ¹³C-NMR spectroscopy were first performed to elucidate the type of interactions between celecoxib (CEL) and hydroxypropyl-β-cyclodextrin (HP-β-CD). Then, solubility studies in the absence and in the presence of HPMC were carried out in aqueous solution. After heating in autoclave of CEL/HP-β-CD/HPMC suspensions a synergistic increasing effect on the aqueous solubility of CEL was observed. In fact, the presence of both HP-β-CD (0.05 M) and HPMC (0.25% w/v) gave rise to a 330-fold CEL solubility increase, whereas the cyclodextrin alone provided a 34-fold increase. Gibbs free energy values calculated from phase solubility data were all negative, indicating the spontaneous nature of CEL solubilization, and they decreased in the presence of HPMC, demonstrating that the solubilization conditions became more favorable. CEL/HP-β-CD and CEL/HP-β-CD/HPMC solid systems (physical mixtures and coevaporated products) were characterized by differential scanning calorimetry and infrared spectroscopy. Results suggested that the coevaporation method yields a high degree of amorphous entities and indicated the formation of a CEL/HP-β-CD complex in the coevaporated products. The positive effect of HPMC is particularly evident when looking at the CEL dissolution rate from the binary and ternary solid systems. Specifically, the percent of CEL dissolved after 10 min. resulted 84.21% for ternary coevaporated product and 50.18% for binary coevaporated product with respect to 13.10% for the drug alone.     

Development of hydrophobic polyurethane film from structurally modified castor oil and its anticorrosive performance

Hydrophobic polyurethane (PU) films are widely used for various commercial and industrial applications due to their excellent water repelling and self-cleaning property. Nevertheless, achieving appreciable hydrophobicity in PU film is quite a challenge. Herein, we report on the development of a novel hydrophobic PU (fluorinated polyurethane [FCO-PU]) film and comprehensively evaluate its anticorrosive property. The FCO-PU was prepared by structural modification of castor oil (CO) through attachment of long fluorocarbon chains as pendant groups onto the backbone of CO. A model PU film (CO-PU) was also prepared from unmodified CO to compare the properties of FCO-PU film. All intermediate compounds, FCO-PU and CO-PU films were characterized by various spectroscopic techniques. Morphological, thermal and mechanical properties of the PU films were analyzed by field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA) studies. Successful introduction of long fluorocarbon chains into the FCO-PU film is reflected by its high hydrophobicity with a water contact angle of 119.1°, compared to the model CO-PU film with a water contact angle of 84.4°. Anticorrosive properties of the PU films were evaluated by polarization technique and electrochemical impedance spectroscopy under corrosive environment and the obtained results reveal a significant corrosion resistance (corrosion rate: 6.72 × 10⁻⁶ mm/year) behavior by the FCO-PU film. This work represents an effective strategy for the backbone modification of CO to develop novel functional PU materials.     

Effect of sugars on the solubility of hydrophobic solutes in water

It was found that the cosolvent effect of sugars on the solubilities of n-octanol, n-heptanol, and sodium dodecyl sulfate monomer in water depended on a set of factors that included molecular weight and concentration ofthe sugars, the kind of monosaccharides, the type of glycosidic linkages involved, and the temperature. All hexoses examined, D-glucose, D-galactose, and D-mannose, caused solubility depression of the hydrophobic solutes at low concentrations but to widely different extents. As the molecular weight of the sugar increased, the solubility depression was considerably lessened and further, as the concentration of the sugars increased, the solubility-increasing effect predominated leading to increased solubilities of the hydrophobic solutes relative of their solubility in pure water. The solubility-increasing effect was markedly enhanced at high temperatures. The free energy of the spontaneous transfer of octanol from water to the sugar solutions is entropic in nature and is attributed primarily to hydrophobic bond formation between the solute molecule and the hydrophobic surfaces of the sugar molecules.     

The wax deposition rate of water-in-crude oil emulsions based on the laboratory flow loop experiment

This paper aims to develop a mathematical model to predict the wax deposition rate of waxy crude emulsions, combining heat and mass transfer mechanisms. According to the flow loop experimental results, the wax deposition rate increases with the decreasing average temperature of oil/wall in a manner of linear regularity, and shows a downtrend with the increase of water cut due to diffusion resistance. An applicable model is developed regarding emulsion properties, radial temperature gradient, shear stress, and wax diffusion coefficient. In model validation, the prediction results are in good agreement with experimental data with the relative errors within 28.87%.     

Synthesis and evaluation of demulsifiers with polyethyleneimine as accepter for treating crude oil emulsions

Demulsifiers provide an important means of breaking water‐in‐crude oil, which are formed during crude oil exploitation. In present work, twenty polyether copolymers based on polyethyleneimine (PEI) were synthesized. The interfacial properties of the PEI polyethers at the water‐crude oil interface were described by interfacial tension (IFT) and interfacial dilational modulus. The effects of position isomerism, size of intermediate and ratio of ethylene oxide (EO)/propylene oxide (PO) on the demulsification efficiency of these polyethers were studied. The results show that different positions of the EO and PO in copolymers lead to huge difference in both interfacial properties and demulsification performance. Polymers with hydrophilic core and hydrophobic tails (Ex‐mn series) are not efficient on demulsification of water‐in‐oil emulsion whereas polymers with hydrophobic core and hydrophilic tails (Px‐mn series) are. Meanwhile, Px‐mn series show higher IFT and lower interfacial dilational modulus than Ex‐mn series. In the same series, the IFT and interfacial dilational modulus decrease with decreasing EO/PO ratio. In the series with best demulsification performance (P199‐mn series), 60 min water removal rates of the polymers increase with decreasing EO/PO ratio at 65°C. In other words, the longer the hydrophobic blocks of polymers, the stronger the demulsification capacity. The effect of concentration of demulsifier on the demulsification efficiency was also investigated. Copyright © 2015 John Wiley & Sons, Ltd.     

A visible coalescence of droplets on hydrophobic and hydrophilic fibers in water-in-oil emulsion

The droplets’ coalescence is instantaneous and rather complex in emulsion. The theoretical analysis of this process was presented by a former research, while visible experiments to verify these are still scarce. This work aims to show and analyze the visible water droplets’ coalescence on hydrophobic bamboo charcoal fibers and hydrophilic glass fibers in water-in-oil emulsion. An experimental setup with microscope and high-speed camera was designed and established to record the water droplets’ coalescence. The water droplets’ collision coalescence on bamboo charcoal fibers was observed, and the diameters of water droplets detaching from the fibers with different angles were measured. The angle between the fiber and the flow velocity can affect the diameters of water droplets detaching from the bamboo charcoal fibers, and cross-fibers can the enormously increase water diameters compared with single fiber. Meanwhile, the water droplets’ collision coalescence on glass fibers was observed and the result shows that the collision coalescence also occurred on the hydrophilic glass fibers when the droplet diameter was small. In addition, other factors, including flow velocity and droplets’ diameter for the coalescence on the hydrophilic glass fibers were investigated.     

Enhanced sedimentation and coalescence of petroleum crude oil emulsions by the new generation of environmentally friendly yellow chemicals

This study compares by means of new and advanced destabilization protocols the efficiency of new chemistry environmentally friendly (yellow) demulsifiers with already commercially available red demulsifiers in destabilizing two types of water-in-oil (w/o) emulsions: petroleum crude oil emulsions and model dense packed layers (DPLs). Oil–water separation profiles were measured by low-field nuclear magnetic resonance (NMR), which allows monitoring the water content as well as the mean droplet size in the emulsion as function of the sample height and the time. Separation profiles measured by NMR depicted an increase of the free water release kinetics as the concentration of demulsifier as well as the sedimentation rate increased. The water resolution was not substantially improved by increasing the concentration further while the water quality was worse, most likely due to adsolubilization. There was no observation of DPL formation in these crude oil emulsions. Four different demulsifiers were tested on a model DPL and compared with normal crude oil emulsions. One chemical showed higher efficiency in destabilizing DPL than destabilizing crude oil emulsion. The interfacial rheological properties for one of the systems showed a slight increase in the elastic modulus (E′), as the concentration of demulsifier increased. The increment of the elastic modulus is not totally understood. The most central parameters were represented by principal component analysis (PCA). PCA did not contribute in a better characterization of the chemicals. The new-generation yellow demulsifiers did not reproduce the efficiency of commercially available, less environmentally friendly, (red) demulsifiers.     

Impact of oil composition on formation and stability of emulsions produced by spontaneous emulsification

In this study, triglycerides of different chain lengths were mixed with paraffin oil, and their effectiveness in forming emulsions produced by spontaneous emulsification upon the addition of water was investigated. The emulsion droplet size exhibited a similar trend as a function of the triglyceride/paraffin oil composition for medium-chain (MCTs) (C8–C10) and long-chain (C18) triglycerides (LCTs). However, emulsions formulated with MCTs and LCTs have a much smaller droplet size (about 50?nm) than emulsions based upon short-chain (C4) triglycerides (SCTs). The addition of SCTs resulted in droplet sizes around 800?nm and the emulsions formed were very unstable. The droplet size, polydispersity index, zeta potential, and emulsion stability of these systems will be described as a function of the oil phase composition.     

A novel method to quantify the amount of surfactant at the oil/water interface and to determine total interfacial area of emulsions

We present a methodology to quantitatively determine the fraction of sodium dodecyl sulfate (SDS) that partitions to the oil/water interface in oil-in-water macroemulsions and calculate the total interfacial area (TIA) through the novel use of filtration through nanoporous membranes. Ultrafiltration was carried out in centrifuge tubes having nanoporous filters with a 30,000 molecular weight cutoff (MWCO), so that emulsion droplets would not pass through, and only SDS (as monomers and micelles) that is in the bulk water phase (i.e., not at the interface) could pass through. The concentration of SDS in the filtrate was determined and used to calculate the TIA for each system. The mean droplet diameter of the emulsions was measured by light scattering. We analyzed the effects of total SDS concentration and oil chain length on the amount of SDS that partitions to the interface, the TIA, and the droplet diameter. The results showed that partitioning of SDS to the oil/water interface increases with increasing total SDS concentration in emulsion systems (i.e., the more SDS we add to the bulk solution, the more SDS partitions to the oil/water interface). However, the surface-to-bulk partition coefficient (i.e., the SDS concentration at the interface divided by the SDS concentration in the aqueous phase) remains the same over the entire concentration range (8-200 mM). The results showed a chain-length compatibility effect in that the minimum amount of SDS partitioned to the interface for C(12) oil. The droplet size measurements revealed a maximum size of droplets for C(12) oil. Penetration of oil molecules into SDS film at the interface has been proposed to account for the maximum droplet size and minimum partitioning of SDS at the oil/water interface for C(12) oil+SDS emulsion system. The TIA, as determined from our ultrafiltration method, was consistently two orders of magnitude greater than that calculated from the droplet size measured by light scattering. Possible explanations for this disparity are discussed.     

磷对NiW/CTS脱残渣油加氢处理催化剂性能的调控作用

以原位生长法制得的Y分子筛/TiO₂-SiO₂ 氧化物（CTS）为载体,以Ni、W为活性金属组分,采用载体表面浸渍磷（P）和在金属组分浸渍液中加入磷（P）的共浸渍方法制备P改性NiW/CTS催化剂,研究了不同P改性方法对催化剂理化性质及加氢性能的影响。实验结果表明,P改性使NiW/CTS催化剂总酸量下降,但表面浸渍P改性使催化剂L酸中心数量下降,而共浸渍P改性使催化剂L酸中心数量增加;P的引入削弱载体与金属间的相互作用,提高金属组分在载体表面的分散性,其中共浸渍P改性法更有利于促使高加氢活性前躯体的形成。因此,共浸渍P改性的催化剂对脱残渣油具有更好的加氢脱硫、脱氮和芳烃饱和性能。     

Effect of hydrophobic units of polycarboxylate superplasticizer on the flow behavior of cement paste

For the tuning of conformation of polycarboxylate (PCE) superplasticizers, hydrophobic groups of different stiffness were incorporated, including styrene (St), methyl methacrylate (MMA), ethyl acrylate (EA), and n-butyl acrylate (n-BA) units. The effect of these hydrophobic groups on the dispersing performance, adsorption process and, rheology of cement paste were investigated. Investigation on the solution conformation and adsorption layer thickness indicated the action mechanism of these groups. High backbone stiffness resulted in a lower extent of conformation condensation from pure aqueous solution to pore solution, and therefore more carboxylic groups could be accessible for adsorption. However, the conformation change after adsorption might also be limited and the size of single molecule after adsorption should be small. Hydrophobic groups always resulted in a coiled PCE conformation in salt solution, which indicated a lower adsorption affinity and thinner adsorption layer for these PCE molecules.