Fabrication of optimized oil–water separation devices through the targeted treatment of silica meshes

Abstract

Efficient oil–water separation is achieved using an optimized superhydrophobic material, generated by the zeolitic roughening and subsequent hydrophobic surface treatment of silica filter membranes. The material is both highly rough and intrinsically hydrophobic, resulting in superhydrophobic membranes which show a substantial affinity for hydrophobic solvents and oils. The membranes are syringe-mounted, suction pressure is applied and the selective collection of oil is achieved. The membranes are extremely robust, which is a result of the zeolitic roughening process, they possess small pores (0.7 μm), as a result these devices can perform complete separation and operate at a range of suction pressures. The devices could be readily used in a range of real-world applications, including oil spill clean-up and industrial filters.     

Effects of mechanical activation on the electrorheological properties of a silicone oil–gibbsite suspension

Changes in the surface state of gibbsite (GB) by milling were elucidated by the electrorheological properties of a suspension comprising GB and silicone oil. Milling GB brought about increase in the amount of readsorbed water as a consequence of mechanochemical dehydration with simultaneous amorphization. In order to discuss the effects of structural imperfections of the substrate induced by milling on the degree of surface polarization, the amount of adsorbed water was precisely controlled by heating at 200°C and subsequent exposure to an atmosphere with predetermined humidity. Compared at the same amount of adsorbed water, the yield stress under 2 kV/mm of the suspension with GB milled for 2 h was about 5 times larger than that of GB milled for 0.5 h. A similar tendency was observed from the creep behavior of the suspension. These electrorheological properties are discussed in the light of enhanced polarization of surface OH groups on the mechanically activated surface of the substrate.     

Characterization of lubricating oil effects on the performance of reciprocating compressors in air–water heat pumps

Lubricating oils play several key roles in compressors, such as lubrication of the parts exposed to friction, prevention of gas leakage at the compression chamber, and cooling of the pieces heated by friction. Oil viscosity and possibility of mixing with refrigerant are the significant factors that should be considered in choosing compatible lubricants. Generally, high viscosity lubricants reduce the efficiency and lubricants with low viscosity cause to direct contact between the metal parts in the compressor. In this study, an experimental procedure has been carried out to investigate the influences of oil circulation in the compressor working with R-404a refrigerant. Although this study has been devoted to a detailed attempt to identify the effects of oil viscosity on energy consumption, an innovative way to analyze this critical parameter has been carried out in parallel with other parameters including refrigerant charge amount, condenser water flow rate and air temperature in the evaporator. The sample oils selected for experiments are SL22, SL68 and SL220. The basic nature of the lubricants and their mixtures with refrigerant, COP value, compressor efficiency and exergetic efficiency of the system has been analyzed under different working conditions.     

The migration characteristics of nanoparticles in the pool boiling process of nanorefrigerant and nanorefrigerant–oil mixture

Migration characteristics of nanoparticles in the pool boiling process of nanorefrigerant and nanorefrigerant–oil mixture are fundamental knowledge for the application of nanorefrigerants in refrigeration systems. In this paper, migration characteristics of nanoparticles in the nanorefrigerant–oil mixture as well as in the nanorefrigerant were experimentally studied and numerically simulated. Experimental results show that the migrated mass of nanoparticles in the pool boiling process of both nanorefrigerant and nanorefrigerant–oil mixture, increase with the increase of the original mass of nanoparticles and the mass of refrigerant; the migration ratio decreases with the increase of volume fraction of nanoparticles; the migrated mass of nanoparticles and migration ratio in the nanorefrigerant are larger than those in the nanorefrigerant–oil mixture. A numerical model, which can qualitatively well predict the migrated mass of nanoparticles, was established, and the deviations between the model predictions and experimental data were in the range of 7.7–38.4%.     

Permafrost and cold-region environmental problems of the oil product pipeline from Golmud to Lhasa on the Qinghai–Tibet Plateau and their mitigation

The 1076-km-long Golmud–Lhasa oil product pipeline is located closely parallel to the highway constructed 20 years earlier within the relatively narrow north–south engineering corridor crossing the treeless central area of the Qinghai–Tibet Plateau. Much of the corridor is at elevations exceeding 4500 m and high-elevation, generally warm permafrost is encountered in more than one-half of the length. The pipeline, transporting mostly diesel, motor and aviation fuels at ambient temperatures, is 159 mm in diameter, has a wall thickness of 6 mm and was buried in a trench at a nominal depth of between 1.2 and 1.4 m. The soils encountered, mostly periglacial sands, silts and gravels, often have elevated saline contents and are subject to severe wind erosion and occasional monsoon flash flooding conditions. During its first quarter century of operation, the pipeline suffered at least 30 significant leaks and four pipeline ruptures. About 337 km of the pipeline was extensively rehabilitated, including relocations or replacements in major problem areas and, where feasible for an existing pipeline, improvements in pipeline protection during 2001–2004. It was supposed to safely operate for another 30 years with proper checks and needed repairs. This paper provides a review on the history of the permafrost and cold regions environmental problems of the pipeline, and their major rehabilitation, repairs and problems in the future, which might have useful implications for similar oil product pipeline at high elevations or permafrost regions.     

Beads made of α-cyclodextrin and soybean oil: the drying method influences bead properties and drug release

Freeze-dried beads made of α-cyclodextrin and soybean oil were reported previously as an efficient system for the oral delivery of lipophilic drugs. In the present study, oven-drying was evaluated as another method for drying beads. Oven-drying was optimised and the properties of the resulting beads were assessed. The behavior of oven-dried beads and the release of indomethacin from these beads were evaluated in vitro in simulated gastrointestinal fluids and compared with those of freeze-dried beads. The stability of freeze-dried and oven-dried unloaded beads stored at 25°C for 12 months and at 40°C for 6 months in closed and open vials was also studied by different techniques. An oven-drying time of 6 hours at 25°C was chosen as optimal conditions. Oven-dried beads exhibited a sticky texture making them difficult to handle. They were harder, less fragile and smaller than the freeze-dried ones. The characteristics of oven-dried beads make them more resistant in vitro even in media containing bile salt. The rate of indomethacin release from oven-dried beads was much slower than that from the freeze-dried ones. Whatever the drying method, beads must be stored at room temperature protected from humidity. However, no products of oil degradation were detected with both kinds of beads. This work clearly emphasized that the drying method of the beads had a strong influence on their properties, behavior in simulated gastrointestinal fluids and drug release.     

On the Correction of the Melting Curve of the Eutectic Co–C for the Effect of the Thermal Inertia of the Furnace

This paper considers the influence of the thermal inertia of the furnace on the shape of the melting curve of the eutectic Co–C. To this end, melting experiments have been performed in a uniform three-zone furnace, with an inherent substantial thermal inertia. The thermal inertia has been quantified by measuring the step-response of the furnace with the sample in its solid state, just below its melting temperature. From the analysis of the effect of the thermal inertia of the furnace, it turned out that during melting the temperature distribution within the furnace, surrounding the crucible, is bound to be in a non-stationary state. This provided the key to properly finalizing the correction to be applied. The shape of the corrected curve differs considerably from that of the curve, as measured, in that the former shows a flatter melting plateau, and a larger curvature on the way down to the solidus point. As regards the liquidus temperature \(T_{\mathrm{liq}}\)—of major interest in the characterization of the transition temperature of high-temperature fixed points—it is demonstrated that the thermal inertia of the furnace shows a kind of self-compensating mechanism. But the effects of the thermal inertia of the furnace on the parameters defining the Scheil fit, involved in the correction procedure, were considerable.     

Investigation of the Dynamics of Evaporation of Condensed Bodies on the Basis of the Law of Spectral‐Radiation Intensity of Particles

The fundamentals of radiation theory and the mechanism of evaporation of condensed bodies are presented. The distribution functions of particles of a body by energies and by the intensity of their transition from one energy level to another in the process of evaporation have been obtained based on the law of spectralradiation intensity of the body particles. The temperature dependence of the resulting vapor flow on the outer surface of a massive condensed body and a thin layer in equilibrium and nonequilibrium states, which, in the limit, transforms to the known Hertz–Knudsen formula, has been found.     

Some features of the transgranular embrittlement of α-titanium alloys under the influence of the environment

Some common features of the transgranular embrittlement of -titanium alloys in chloride solutions, hot salts, liquid metals, and air are established. These types of brittle fracture are typical symptoms of trans-granular embrittlement along the basal (near-basal) cleavage planes of metals (alloys) with hcp crystal lattices with various values of the ratioc/a. In this connection, the role of alloying elements and the mechanism of corrosion cracking of -titanium alloys in chloride solutions are reconsidered.Central Scientific Research Institute of Structural Materials Prometheus, St. Petersburg. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 1, pp. 75–77, January–February, 1994.     

The improvement of the amorphous environment of the germanate–tellurate glasses in the presence of the gadolinium ions

Glasses in the system xGd₂O₃·(100 − x)[TeO₂·GeO₂] with 0 ≤ x ≤ 50 mol% have been prepared from melt quenching method. In this paper, we investigated changes of the coordination numbers of germanium, tellurium, and gadolinium ions by investigations of FTIR, EPR, and UV–VIS spectroscopy. By analyzing the structural changes resulted from the IR spectra we found that the bending modes of [GeO₄] structural units and the deformed modes of the Te–O–Te linkages produce intercalation of the [GdO _n ] entities in the germanate–tellurate chain network and densification of the glasses by increasing the number of [GeO₆] structural units. EPR spectra of the studied samples reveal that the gadolinium ions play a role of network former. The UV–VIS spectra show broad UV absorption bands located in the 250–350 nm region. Their intensity increase with the increasing of Gd₂O₃ content showing that these stronger transitions can be due to the presence of the O=Ge bonds (n–π* excitations) of [GeO₅] structural units. The [GeO₅] structural units are more stable thermodynamically than their analogues and the [GeO₆] structural units produce the improvement of the amorphous character of these glasses.     

On the Origin of the δk-Model and the Model of Plastic Strips

On the basis of a survey of works, we demonstrate the priority of the Lviv school of mechanics in the field of creation and development of the deformation theory of limiting equilibrium of bodies with cracks known as the _k -model. The theory is based on the criterion of crack opening displacement proposed by Leonov and Panasyuk and on the procedure of evaluation of this quantity by modeling the inelastic zones in front of the crack by cuts the edges of which are loaded by certain stresses ₀ whose physical meaning is determined by the properties of the material. This method (known as the model of plastic strips) is also used for the determination of the development of plastic zones at the crack tip for various configurations of plates and loads and also in twisted bodies. The results of numerical calculations agree with the experimental data.     

Measurement of the activity of individual subunits of single molecules of the tetrameric enzyme β-galactosidase

Escherichia coli β-galactosidase was incubated in the presence of the slow-release inhibitor D-galactal for 30 min at a concentration of 70 times its K(i). The sample was then diluted 20000-fold into buffer containing the fluorogenic substrate 9H-(1,3-dichloro-9,9-dimethylacridin-2-on-7-yl) β-D-galactoside, reducing the inhibitor concentration to K(i)/280. The sample was subjected to a capillary electrophoresis continuous flow single enzyme molecule assay. As the inhibitor dissociated while the enzyme traveled the length of the capillary, a fraction of molecules showed stepwise increases in activity. This was due to the activation of individual subunits within single molecules. The changes in activity can be largely explained in terms of each molecule containing subunits of indistinguishable activity.     

Investigation of the Serviceability of the Heat Shield of the Orbital Aircraft “Buran” under the Conditions of Radiant Heating on Solar Plants

We have investigated the serviceability of the heatinsulating tiles of the orbital aircraft Buran under radiant heating on an SGU7 solar plant with a mirror concentrator 5 m in diameter. Cycles of aerodynamic heating with a duration of 20 min were simulated. For the total number of cycles for different materials from 20 to 85, the efficiency and serviceability of TZMKtype materials with different coats have been corroborated. The results obtained agree with the test data obtained on gasdynamic (power consumption 1 MW) and radiation (250 kW) test beds, which enables such tests to be recommended for use at preliminary stages in powersaving and ecologically harmless solar furnaces.     

Flexural toughness characteristics of steel–polypropylene hybrid fibre-reinforced oil palm shell concrete

Hybridization of steel–polypropylene leads to improvements of both the mechanical and ductility characteristics of concrete. In this investigation, the effect of steel, polypropylene (PP) and steel-PP hybrid fibres on the compressive strength, tensile strength, flexural toughness and ductility of oil palm shell fibre reinforced concrete (OPSFRC) was studied. The comparison on the above said properties between the specimens prepared with crushed and uncrushed oil palm shell (OPS) as lightweight coarse aggregate was also carried out. The experimental results showed that the highest compressive strength of about 50 MPa was produced by the mix with 0.9% steel and 0.1% PP hybrid fibres. The highest increments in the splitting tensile and the flexural strengths of the OPSFRC were found up to 83% and 34%, respectively. However, the mixes with 1% PP fibres produced negative effects on both the compressive and tensile strengths. The results on the toughness indices showed that the OPSC possess no post-cracking flexural toughness. Though, the flexural deflection and toughness of the OPSC was significantly enhanced by the addition of fibres; the dominance of the steel fibre on the first crack flexural deflection and toughness of OPSFRC was evident. The mixes with 0.9% steel and 0.1% PP hybrid fibres reported the highest improvement in toughness index and residual strength factor.     

Effects of storage temperature and α-tocopherol on oil recovered from sardine mince

Sardine oil released during sardine mince preparation showed good quality with a low hydroperoxide content, excellent color and high content (19.23%) of eicosapentaenoic acid. Recovered sardine oil was stored at two different temperatures (+4 °C and +35 °C) for 28 days with or without the addition of α-tocopherol (50 and 100 ppm). Peroxide values and thiobarbituric acid reactive substances of control sardine oil significantly increased to reach 29.9 meq O₂/kg oil and 46.48 mg MA/kg during storage at +35 °C, but the increase was considerably less (4.36 meq O₂/kg oil and 13.21 mg MA/kg oil respectively) in oil stored at +4 °C. A slight increase (1.5%) in the free fatty acid content was recorded in oil stored at 35 °C. A significant decrease of polyunsaturated fatty acids was recorded after storage, particularly in oil stored at 35 °C, while higher percentages of saturated and monounsaturated fatty acids were observed. Storage at +4 °C combined with addition of α-tocopherol (100 ppm) had a beneficial effect on sardine oil stability.     

Effect of the length and the aggregate size of MWNTs on the improvement efficiency of the mechanical and electrical properties of nanocomposites—experimental investigation

An experimental investigation of the effect of nanotube length and aggregate size on the mechanical and electrical properties of the composites was reported. Three treatments, that affect mainly the length and aggregate size, were applied on the CVD MWNTs before they were added into a resin matrix. They had a very clear impact on the dielectric properties of the composites and on the improvement efficiency. There was an insulator-to-conductor transition with the as-prepared MWNTs at 0.5 wt%. Regarding the mechanical properties, the addition of MWNTs increased the Young's modulus and reduced the fracture strain. In that case, the pre-treatment on MWNTs, however, had a much more moderate effect on the improvement efficiency.