PREPARATION OF CLOUDY COCONUT OIL EMULSIONS CONTAINING DISPERSED Ti02 USING ATOMIZER

Food Grade Rutile TiO₂ was dispersed in coconut oil with the help of hydrophobic emulsifiers such as sorbitan esters and lecithin. The dispersed mixture was melted and blended with hydrophilic emulsifiers such as ethoxylated sorbitan esters and the preheated (60°C) blend was further sprayed by atomizer into cold water (20°C). The oil-in-water emulsions contained encapsulated TiO₂ in the internal phase. The technique is simple and allows preparation of stable emulsions with average droplet size of 1-10 microns.     

Synthesis of zinc borate by inverse emulsion technique for lubrication

Lubricating oil additives based on boron compounds are promising materials for lubrication due to their tribological advantages such as antiwear efficiency, good film strength, and high temperature resistance. This article deals with the preparation of zinc borate particles that are well dispersed and colloidally stabilized in mineral oil. This method starts with preparing two inverse emulsions (water-in-oil) with sorbitan monostearate (Span 60) as a surfactant, light neutral oil as a continuous phase, and the aqueous solutions of borax decahydrate (Na₂B₄O₇·10H₂O) and zinc nitrate (Zn(NO₃)₂·6H₂O) as the dispersed phases. The produced particles were zinc borate crystals having both rod-like and spherical morphologies, and the diameters of spherical particles were changing between 20 and 30 nm. FTIR spectra of the obtained particles showed the characteristic peaks of trihedral borate (B(3)-O) and tetrahedral borate (B(4)-O) groups as well as the specific peaks of the sorbitan monostearate. TG showed 30.42% and 22.08% mass loss at 600 °C for the samples prepared by inverse emulsion and precipitation techniques, respectively. The endothermic peak at 50 °C is observed due to the melting of sorbitan monostearate and the heat of melting is evaluated as −3.50 J/g. Tribological studies revealed that sorbitan monostearate not only outperformed as a dispersing agent of inorganic particles, but also it proved to be an anti-wear agent. Zinc borate produced by precipitation decreased the wear scar diameter from 1.402 to 0.639 mm and the friction coefficient from 0.099 to 0.064. The inverse emulsion was effective in decreasing wear scar diameter and the friction coefficient by lowering them to 0.596 and 0.089 mm, respectively.     

The Stability of Highly Concentrated Water-in-Oil Emulsions and Structure of Highly Porous Polystyrene Produced from Them

The porosity of polymer materials produced by polymerizing dispersion media of highly concentrated emulsions may be predicted, provided that the emulsions are stable. The study of the stability of water-in-oil (W/O) emulsions containing styrene as a dispersion medium at 25 and 65°C has shown that emulsions with a dispersed phase fraction of 0.75 and sorbitan monooleate concentrations of 1.5–20.0 vol % are stable to coalescence but are unstable to sedimentation. Emulsions with a dispersed phase fraction of 0.95 are stable to both coalescence and sedimentation at sorbitan monooleate concentrations of 10–20 vol %. Open-pore polymer materials are formed from emulsions with dispersed phase fractions of 0.75 and 0.95 at sorbitan monooleate concentrations of 2.0–3.5 and 10–12 vol %, respectively. At a dispersed phase fraction of 0.75 and a sorbitan monooleate concentration of <2 vol %, a multiple O/W/O emulsion is formed, the polymerization of which yields a porous polymer material containing spherical polystyrene particles inside pores. At higher surfactant concentrations in emulsions with dispersed phase fractions of 0.75 and 0.95 partly destroyed porous materials are formed.     

Fabrication of durable superhydrophobic nanofibrous filters for oil‐water separation using three novel modified nanoparticles (ZnO‐NSPO,AlOO‐NSPO,and TiO2‐NSPO)

Three reusable and durable superhydrophobic nanofibrous filters were prepared by dip coating the nanofibrous fabric in the three different dispersed solutions of the newly modified nanoparticles (ZnO‐NSPO, AlOO‐NSPO, and titanium dioxide [TiO₂]‐NSPO). The contact angle results proved that the TiO₂‐NSPO coated nanofibrous polyacrylonitrile (PAN) filter was hydrophobic with the water contact angle (WCA) of 141° while the ZnO‐NSPO and AlOO‐NSPO coated nanofibrous PAN filters were superhydrophobic with the WCA of 168° and 152°, respectively. The as‐prepared filters can be utilized as an effective martial for oil‐water separation with separation efficiency of over 98%.     

淀粉/丙烯酸反相乳液体系的稳定性研究

以丙烯酸(AA)单体的水溶液为水相,液体石蜡为油相,失水山梨醇三油酸酯(Span 85)和辛基苯基聚氧乙烯醚(Opan 10)为复合乳化剂,合成了淀粉/丙烯酸反相乳液;考察了乳化剂亲水亲油平衡值(HLB值)、油水比、乳化剂用量、单体浓度、温度对乳液稳定性和类型的影响.结果表明,合成淀粉/丙烯酸稳定反相乳液体系的适宜条件...     

Flexible Hierarchical TiO2/Fe2O3 Composite Membrane with High Separation Efficiency for Surfactant‐Stabilized Oil‐Water Emulsions

Globally, efficient oil‐water separation for surfactant‐stabilized oil‐water emulsions has been in urgent demand. The current options available for separation are neither sustainable nor resistant to fouling. Herein, we introduce a hierarchically nanostructured TiO₂/Fe₂O₃ composite membrane, which is capable of separating surfactant‐stabilized oil‐water emulsions with high separation efficiency. The high oil rejection rate is contributed by the acquisition of an interconnected delicate network and underwater superoleophobic interface. Meanwhile, its self‐cleaning function promote the facile recovery of the contaminated membrane. Furthermore, the mechanical flexible characteristic of the TiO₂/Fe₂O₃ composite membrane widens its applicability in industrial employment. Thanks to these properties, this novel membrane can be considered as a practical option for treating surfactant‐stabilized oil‐water emulsions.     

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.     

Study on the Photodegradation of Salicylic Acid in Different Vehicles in the Absence and in the Presence of TiO2

In this work, the direct photolysis of salicylic acid, generally used as keratolytic agent in many dermatological products and as preservative in cosmetics, was investigated. The photodegradation of the acid under UVB irradiation was evaluated in different vehicles, such as water solutions at different pH, propylene glycol/water, and ethanol/water mixtures, sodium dodecyl sulphate solutions, and O/W emulsions prepared with Montanov 68 and Amphysol K as emulsifiers. The increase of pH enhanced the photodegradation of salicylic acid while the different vehicles protected the acid from the action of UVB radiations. However, the best protection was observed dissolving the acid in the lipid core of O/W emulsions, which probably removes the active from the polar environment that can promote the photolysis. The photocatalytic activity of TiO₂ on the degradation of salicylic acid also was evaluated. TiO₂ frequently is used as sunscreen in many cosmetic preparations. Salicylic acid and the pigment can be contained in the same solar formulation; hence, it can be interesting to study their interaction under UVB. TiO₂ enhanced the photodegradation of salicylic acid in all the media previously reported and its photocatalytic activity was influenced by the pH and by the components of the vehicles.     

Hydrophilic polymer foams with well‐defined open‐cell structure prepared from pickering high internal phase emulsions

Open‐cell hydrophilic polymer foams are prepared through oil‐in‐water Pickering high internal phase emulsions (HIPEs). The Pickering HIPEs are stabilized by commercial titania (TiO₂) nanoparticles with adding small amounts of non‐ionic surfactant Tween85. The morphologies, such as average void diameter and interconnectivity, of the foams can be tailored easily by varying the TiO₂ nanoparticles and Tween85 concentrations. Further, investigation of the HIPE stability, emulsion structure and the location of TiO₂ nanoparticles in resulting foams shows that the surfactant tends to occupy the oil‐water interface at the contact point of adjacent droplets, where the interconnecting pores are hence likely to be formed after the consolidation of the continuous phase. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

The crystallization of anatase and the conversion to bronze-type TiO2 under hydrothermal conditions

When the anatase form of TiO₂ was heated at a constant rate of 6°C/min to 450°C it crystallized from hydrated amorphous TiO₂ gel at 170°C in pure water or at <150°C in NaOH solutions. The uptake of Na⁺ ions into crystallized anatase affected the reactions subsequent to this initial crystallization while only anatase crystals continued to grow with increasing temperature in pure water. Immediately after the nearly amorphous second stage at 325°C, conversion from colloidal anatase particles to square sheet-shaped bronze-type TiO₂ crystals began at 350°C and was complete at 425°C in 0.5 M NaOH. This conversion was considered to proceed via crystallographic shear rather than via dissolution and precipitation since this also happened with thermal treatment to 700°C in air.     

Effect of calcination temperature on the photocatalytic activity of carbon‐doped titanium dioxide revealed by photoluminescence study

Carbon‐doped titania (C‐TiO₂) nanoparticles were synthesized by the sol–gel method at different calcination temperatures (300–600°C) employing titanium tetraisopropoxide (TTIP) as the titanium source and polyoxyethylene sorbitan monooleate (Tween 80) as the carbon source. The physical properties of C‐TiO₂ samples were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activities were checked through the photodegradation of phenolphthalein (PHP) under ultraviolet irradiation. The UV spectrum showed that the carbon doping extends the absorption range of TiO₂ to the visible region. However, the photocatalytic activity is affected by the electron–hole recombination phenomenon, as revealed by the photoluminescence (PL) study. According to the PL spectra, carbon doping reduces the edge‐to‐edge electron–hole recombination. Nevertheless, the number of defect sites is greatly influenced by the calcination temperature of C‐TiO₂. C‐TiO₂ that was calcined at 400°C showed the highest photodegradation percentage of PHP, which was mainly attributed to the synergic effect of the low direct edge‐to‐edge electron–hole recombination, high content of defect sites, and retention of active electrons on the surface hydroxyl group.     

Oil Base Mud. Part I: Synthesis of Some Local Surfactants Used as Primary Emulsifiers for Oil Base Mud and Evaluation of Their Rheology Properties

Six oil soluble nonionic surfactants with different HLBs have been prepared. Their HLBs situate between 3.9 and 6.7. Transesterification was carried out for glycerol and triethanol amine with oleic acid at different moles to obtain six emusilifiers. They named glycerol momooleate (I), glycerol diooleate (II), glycerol trioleate (III), triethanol amine mono-, di- and tri-oleate (IV), (V,) and (VI). The chemical structure was confirmed using; the elemental analysis, FTIR and ¹HNMR. They were evaluated as a primary emulsifiers (PE) for thdrilling fluids (oil base mud) comparing with a currently used primary emulsifier (Fc). The water in oil base mud (w/o emulsions) was prepared. The concentration of emulsifiers and their HLB exhibited interesting rheology properties including shear-thinning behavior, yield value, viscoelastic effects, thixtropy, gel strength, and filtration loss. The rheology properties of such emulsions strongly depended on the average size distribution of the dispersed droplets that could be varied both with the bulk concentration and HLB value of the emulsifiers. The interfacial and surface properties of these emulsifiers suggest that the droplet size of the dispersed phase and bulk concentration are strongly related to the HLB value of emulsifiers. The w/o emulsion (mud formulation) stability is sensitive to the droplet size of the dispersed phase and HLB value of the used emulsifier. The results were discussed on the light the chemical structure of the primary emulsifiers and the emulsion ingredients.     

STABILIZATION OPTIMIZATION OF AQUEOUS MONOMER SOLUTIONS IN OIL EMULSIONS USING THE COHESIVE ENERGY RATIO CONCEPT.

The Beerbower-Hill approach based on the Cohesive Energy Ratio concept (CER) has been applied in order to optimize the stabilization of Acrylamide-water or Acrylic Acid (pure and 80% neutralized)- water mixtures in cyclohexane emulsions.

Using surface tension measurements for the determination of the solubility parameter of the aqueous phase ( δ_w), it was found that the presence and amount of the water-soluble monomer could be accounted for the evaluation of the optimal HLB.

Predictions were compared to experimental HLB values obtained by using various blends of a low-HLB emulsifier (a sorbitan monooleate named MONTANE 80) and high-HLB emulsifiers (either a nonylphenolpolyoxyethylene [40 EO] or a pOE [20 EO] sorbitan trioleate, MONTANOX 85).     

The use of sulfated tin oxide as solid superacid catalyst for heterogeneous transesterification of <Emphasis Type="Italic">Jatropha curcas</Emphasis> oil

This work presents the use of sulfated tin oxide enhanced with SiO₂ (SO₄²⁻/SnO₂-SiO₂) as a superacid solid catalyst to produce methyl esters from Jatropha curcas oil. The study was conducted using the design of experiment (DoE), specifically a response surface methodology based on a threevariable central composite design (CCD) with α = 2. The reaction parameters in the parametric study were: reaction temperature (60°C to 180°C), reaction period (1 h to 3 h), and methanol to oil mole ratio (1: 6 to 1: 24). Production of the esters was conducted using an autoclave nitrogen pressurized reactor equipped with a thermocouple and a magnetic stirrer. The maximum methyl esters yield of 97 mass % was obtained at the reaction conditions: temperature of 180°C, reaction period of 2 h, and methanol to oil mole ratio of 1: 15. The catalyst amount and agitation speed were fixed to 3 mass % and 350–360 min⁻¹, respectively. Properties of the methyl esters obtained fell within the recommended biodiesel standards such as ASTM D6751 (ASTM, 2003).     

Kinetics of the photoinitiated inverse microemulsion polymerization of 2-methacryloyl oxyethyl trimethyl ammonium chloride

The polymerization of inverse microemulsions of 2-methacryloyl oxyethyl trimethyl ammonium chloride stabilized by a blend of nonionic emulsifiers (a sorbitan sesquioleate and a sorbitan monooleate) and initiated by UV light in the presence of Azobis(isobutyronitrile) (AIBN) was investigated. The effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the polymerization rate (R_p), number of polymer particles (N_p), and polymer molecular weight (M_w) was studied. The application of this process to tubular reactors is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 737–748, 1998     

EMULSIFICATION BY CHEMICALLY MODIFIED OVALBUMIN

Enhancement of emulsifying properties of a model protein, ovalbumin, was achieved by covaient attachment of hydrophobic groups using various esters of N-hydroxysuccinimide. It was found that the resulting modified proteins were much better emulsifiers than the native ovalbumin, even at low modification degree (20-30% of available amine groups): in tetradecan-water emulsions oil separation was observed within a few hours, when 0·7 mg/ml native ovalbumin was used, compared to about one month until separation was observed when the modified proteins were used. The use of highly modified proteins prevented completely oil separation (at least two months); for example, emulsions prepared with 51% modified proteins with C₃, C₆, showed no change in droplet size distribution even 50 days after preparation. The effect of chain length on emulsification was also investigated: an optimal chain length (Cg) was found, for both low and high modifications.     

In Situ Dispersion of Palladium on TiO2 During Reverse Water–Gas Shift Reaction: Formation of Atomically Dispersed Palladium

The application of single-atom catalysts (SACs) to high-temperature hydrogenation requires materials that thermodynamically favor metal atom isolation over cluster formation. We demonstrate that Pd can be predominantly dispersed as isolated atoms onto TiO₂ during the reverse water–gas shift (rWGS) reaction at 400 °C. Achieving atomic dispersion requires an artificial increase of the absolute TiO₂ surface area by an order of magnitude and can be accomplished by physically mixing a precatalyst (Pd/TiO₂) with neat TiO₂ prior to the rWGS reaction. The in situ dispersion of Pd was reflected through a continuous increase of rWGS activity over 92 h and supported by kinetic analysis, infrared and X-ray absorption spectroscopies and scanning transmission electron microscopy. The thermodynamic stability of Pd under high-temperature rWGS conditions is associated with Pd-Ti coordination, which manifests upon O-vacancy formation, and the artificial increase in TiO₂ surface area.     

Effects of emulsifying agents on the safety of titanium dioxide and zinc oxide nanoparticles in sunscreens

The use of titanium oxide (TiO₂) and zinc oxide (ZnO) nanoparticles (NPs) in sunscreen formulations has increased considerably, and might pose a serious health hazard worldwide. A thorough investigation into the toxicity induced by such components is highly necessary. In this study, the effects of TiO₂ and ZnO NPs on HaCaT cells were tested in the presence and absence of emulsifiers (cyclopentasiloxane, jojoba ester, and lecithin). Cell viability results revealed that the toxicity of NPs was highly dose dependent and influenced by the emulsifier type. The emulsifiers themselves are minimally toxic. However, when used in combination with TiO₂ and ZnO, they were highly toxic to HaCaT cells. Transmission electron microscopy revealed that the cells showed least permeability to NPs dispersed in lecithin compared to other emulsifiers. In conclusion, the toxicity of NPs may be highly dependent on the emulsifier type and be varied. In particular, lecithin can be used as a potential alternative emulsifier in sunscreens.     

Thermo‐Driven Controllable Emulsion Separation by a Polymer‐Decorated Membrane with Switchable Wettability

A thermoresponsive Poly(N‐isopropylacrylamide) (PNIPAAm)‐modified nylon membrane was fabricated via hydrothermal route. Combining rough structure, proper pore size, and thermoresponsive wettability, the membrane can separate at least 16 types of stabilized oil‐in‐water and water‐in‐oil emulsions at different temperatures. Below the LCST (ca. 25 °C), the material exhibits hydrophilicity and underwater superoleophobicity, which can be used for the separation of various kinds of oil‐in‐water emulsions. Above the LCST (ca. 45 °C), the membrane shows the opposite property with high hydrophobicity and superoleophilicity, and it can then separate stabilized water‐in‐oil emulsions. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions and the hydrothermal method is facile and low‐cost. The membrane shows good potential in real situations such as on‐demand oil‐spill cleanup, industrial wastewater treatment, remote operation of oil/water emulsion separation units, and fuel purification.     

Ionic Liquids as Internal Phase for Non‐Aqueous PolyHIPEs

Stable high internal phase emulsions (HIPEs) with the ionic liquid 1‐ethyl‐3‐methylimidazolium bis(trifluoromethyl‐sulfonyl)imide as dispersed phase were prepared and polymerised thermally into polyHIPEs. All polyHIPEs exhibited pore morphologies similar to that of polyHIPEs obtained with an aqueous dispersed phase. PolyHIPEs containing the dispersed phase possess a low T_g and are thermally stable in excess of 200 °C, offering the potential for new porous materials where water as dispersed phase is chemically or physically undesirable.