High Oil Retention Research Articles

Selectively enhanced oil retention of porous polyimide bearing materials by direct chemical modification

ABSTRACTPorous polyimide (PI) materials containing lubricating oil have been widely used as bearing retainers in aerospace industry. High oil content and retention of porous bearing materials play an important role in assuring a successful mission of the spacecraft. Keeping both oil content and retention of bearing retainer materials high, however, is one of the bottlenecks to fulfill long lifetime missions. Chemical modification is expected to break this limitation by changing the surface properties. Inspired by this, here for the first time, the authors design a chemical method to improve silicon oil retention of porous PI samples. The results indicated that this modification could not only change the wettability of PI from hydrophilicity to hydrophobicity but also enhance the silicon oil retention from 52% to 87%. This strategy provides a novel approach to improve the oil retention of porous PI materials, which has the potential application in preparing bearing retainers with reliable, long‐term performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45106.

Oil Spill Cleanup by Hydrophobic Natural Fibers

ABSTRACTThis article evaluates and compares on oil wetting and sorption performance of three natural fiber assemblies made by kapok, cattail and cotton fibers in application of absorbing vegetable oil. The three fibers were naturally hydrophobic and oleophilic. The water stood on the fibers’ surfaces with the contact angles between 120° and 145°, while oil droplet disappeared quickly from the fibers’ surfaces within several seconds. When applied as the oil sorbents, it was found that the three fiber assemblies showed quick oil uptake. Among them, kapok fiber assembly showed exceptionally high oil sorption and retention capacity. The presence of big hollow lumens which contributed to 77 % of the fiber’s volume was the important reason for this. Cattail fiber was bamboo-shaped. The fiber was short (3–11 mm). However, the formation of numerous of bamboo-liked lumens between neighboring fibers in cattail fiber assembly contributed to it quick oil sorption and excellent oil retention capacity, despite of relatively low oil absorbency. Although faster oil spreading comparing to kapok fibers, cotton fibers showed much lower oil absorbency and retention capacity, due to its collapsed lumens which considerably reduced its available pores for oil sorption.

The synthesis of hierarchical porous Al2O3/acrylic resin composites as durable, efficient and recyclable absorbents for oil/water separation

In this work, we report a facile and inexpensive approach which was demonstrated for the creation of hierarchical porous Al2O3/acrylic resin composites as durable, efficient and recyclable absorbents for oil/water separation. Using hexadecyl trimethyl ammonium bromide (CTAB) as a structure-directing agent, the lamellar γ-AlOOH with porous architectures was successfully prepared via a hydrothermal route. The hierarchical Al2O3 clusters, as the inorganic phase of resin composites, retain the unique structure of lamellar γ-AlOOH by calcination treatment. In order to enhance the hydrophobic and oleophilic properties of Al2O3 clusters, silane coupling agent (A151) was used to modify the surface of Al2O3 clusters under microwave irradiation. The surface modified Al2O3 clusters exhibit excellent hydrophobicity, oleophilicity and chemical stability, owing to the tight binding of the hydrophobic functional groups on the inorganic Al2O3 clusters and the inherent stability of the grafted hydrophobic molecule chains. The porous Al2O3/acrylic resin composites were synthesized by suspension polymerization of butyl acrylate (BA) and methacrylic acid butyl ester (MBA) on the surface modified Al2O3 clusters under microwave irradiation in the presence of coupling agents. The porous Al2O3/acrylic resin composites can effectively separate oils and organic solvents with high oil absorption rate and high oil retention capacity. Moreover, the obtained resin composites have high oil uptake capacities due to the synergy absorption of porous Al2O3 clusters and acrylic resin. These excellent performances, such as excellent oil recoverability, excellent recyclability and high oil retention capacities, endow the material to be an ideal candidate to separate a variety of organic liquids from water.

Desolventizing of soybean oil/azeotrope mixtures using ceramic membranes

ABSTRACT This work investigates the use of ceramic membranes with different molecular weight cut-offs (MWCOs: 5, 10 and 20 kDa) to desolventize azeotropic solvent mixtures (ethanol/n-hexane and isopropyl alcohol/n-hexane) from soybean oil/azeotrope micelles. Results show that a decrease in the MWCO of a membrane and an increase in the solvent mass ratio in the mixture resulted in a significant reduction in the permeate flux. The 20 kDa membrane presented the highest permeate flux, 80 and 60 kg/m2h for the soybean oil/n-hexane/isopropyl alcohol and soybean oil/n-hexane/ethanol azeotropes, respectively, for an oil to solvent ratio of 1:3 (w/w). The highest oil retention was found using the n-hexane/isopropyl alcohol azeotrope, around 25% in the membrane with the lowest MWCO, that is, 5 kDa. It is shown that the azeotropic mixtures provided intermediate characteristics compared to the original pure solvent behavior.

Hydrophobic Modification of Platanus Fruit Fibers as Natural Hollow Fibrous Sorbents for Oil Spill Cleanup

The Platanus fruit fibers (PFFs) with unique hollow tubular structures were successfully utilized in the preparation of an efficient oil sorbents for the first time by chemical modification with acetic anhydride. The structure and morphology of the pristine PFFs (p-PFFs) and acetylated PFFs (a-PFFs) were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of acetic anhydride to PFFs ratio, catalyst concentration, reaction temperature, and time on the weight percent gain (WPG) and oil sorption capacity were particularly investigated in detail. The results showed the hydrophobic modification of p-PFFs contributed to the enhancement of the sorption capacity of a-PFFs for various oils and organic solvents. The sorption kinetic analysis indicated the oil sorption data were fitted well with a pseudo-second-order kinetic model. And the oil-filled a-PFFs exhibited high oil retention ability with less than 30 % of the sorbed oil lost after 2-h dripping. Moreover, a-PFFs showed little loss of initial sorption capacities after eight sorbing/desorbing cycles with the recovery of sorbents by n-hexane extraction. The natural renewable a-PFFs are proved to be a promising candidate for large-scale removal of spilled oils from water.

Studies on needle-punched natural and polypropylene fiber nonwovens as oil sorbents

This article reports on oil sorption behavior of needle-punched nonwoven fabrics made from milkweed, kapok, cotton and polypropylene fibers using air-lay and carding technologies. The effects of fiber and fabric parameters on oil sorption and retention capacities, and oil sorption rate and fabric strength were investigated. Fabrics made using natural fibers such as milkweed and cotton were found to selectively absorb oil over water. Milkweed and kapok nonwovens displayed higher oil sorption and retention capacities as compared to cotton and polypropylene nonwovens. Further, milkweed and kapok nonwovens exhibited higher oil sorption rate as compared to cotton and polypropylene nonwovens. The porosity of nonwoven fabric was found to play a vital role in determining the oil sorption capacity. Although the web-forming technology did not affect the oil sorption and retention capacities and oil sorption rate, it affected the fabric strength significantly. Cotton nonwoven kept on artificial sea water for 10 days displayed very low water sorption capacity, although the nonwovens produced using natural fibers exhibited preferential sorption of oil over water and high oil sorption and retention capacities; which are advantageous in using them as oil sorbents to cleanup oil spills on oceans, but they offered low fabric strength. These findings indicate that further research works are required to improve the strength of natural fiber nonwovens for sustainable oil spill removal.

Toluene diisocyanate based phase-selective supramolecular oil gelator for effective removal of oil spills from polluted water

Due to tremendous resource wastes and great harm to ecological environment caused by the accidental oil spills, an alkyl bicarbamate supramolecular oil gelator was synthesized and applied to selectively gelate oils from oil/water mixtures. Interestingly, the oil gelator could be self-assembled in a series of organic solvents, i.e., edible oils and fuel oils to form 3D networks and then turned into thermally reversible organogels, allowing easy separation and removal of oil spills from oil/water mixtures. The possible self-assembly mode for the formation of organogels was proposed. What's more, the optimal conditions for using the oil gelator to recover oils were experimentally determined. Inspiringly, taking gasoline as the co-congealed solvent, a complete gelation of oil phase was achieved within 15 min with high oil removal rate and oil retention rate after convenient salvage and cleanup of oil gels from oil/water mixtures. The oil gelator had some advantages in solidifying oil spills on water surface, exhibiting fast oil gelation, convenient and thorough oil removal and easy recovery. This work illustrates the significant role of oil gelators in the potential cleanup of spilled oils for water purification.

Highly porous oil sorbent based on hollow fibers as the interceptor for oil on static and running water

Highly porous fibrous assembly made by kapok and hollow PET fibers was prepared by the air-laying-bonding method, and used as the interceptor for oils on static and running water. SEM showed that the vast majority of kapok and PET fibers in the assembly was intact and retained their hollow lumens, with the assembly's porosity high to 98.03%. Oil sorption tests exhibited that kapok/PET assembly could absorb 63.00g/g of vegetable oil and 58.50g/g of used motor oil, with high oil retention after 24h dripping. In static condition of oil interception, the two oils started to leak at around 20min for 10-mm thick kapok/PET wall. The time for that was prolonged with increasing the thickness of kapok/PET wall. After oil breakthrough, continuous oil leaking took place. The typical leakage was divided into three stages in which oils leaked separately in sharply increased rate, reduced rate and finally gently. In running condition, oils leaked in markedly quicker way than that in static condition, with initial leakage of oils shortened to less 6min when the water ran at 60.35ml/s. The leakage of oils was considerably accelerated with increasing running rates.

Optimization of oil retention in sesame based halva using emulsifiers and fibers: an industrial assay.

Oil bleeding during storage oleaginous seeds based confectionery products is a major problem affecting acceptance by consumers. Halva is a popular sweet food prepared from a sesame paste and a sugar mixture. The objective of this work was to improve the oil retention in this product by incorporating commercial fibers and emulsifiers: soya lecithin and monoglycerides (MG1 or MG2) during manufacturing. Oil retention yield was optimized on small batches, by response surface methodology using a central composite design applied with two factors, emulsifier concentration (0.25-2.25%) and fibers concentration (0-2%) at three levels. A centrifugation test was optimized to assess oil retention in halva samples. The experimental response (oil retention) was fitted with quadratic equations for each emulsifier, using multiple regression analysis. The emulsion stability increased with increasing the emulsifier concentration, particularly to 2.25%. The oil bleeding assessed at 45°C was slow but yielded similar results to those estimated by centrifugation test. The latter seems an attractive rapid method to quantify oil retention in oleaginous seeds and crops based food matrices. At an industrial scale, the increase of MG1 concentration to 2.25% in halva enhances the oil retention of the product but does not affect its color or textural characteristics. Microscopic observations allowed us to explain high oil retention in this product by a homogeneous dispersion of oil droplets in the aqueous phase.

Surface Hydrophilicity and Structure of Hydrophilic Modified PVDF Membrane by Nonsolvent Induced Phase Separation and Their Effect on Oil/Water Separation Performance

The hydrophilic polyvinylidene fluoride (PVDF) material was prepared by ozone-induced grafting polymerization of acrylic acid on PVDF chains, and used for preparing oil/water separation ultrafiltration membranes by the nonsolvent induced phase separation method. The effect of membrane casting conditions was studied, and the results showed that N-methyl-2-pyrrolidone (NMP) present in the coagulation bath affected the membrane surface hydrophilicity as well as the membrane structure, and that casting solution concentration and air exposure time affected pore size but had little influence on surface hydrophilicity. The effect of material hydrophilicity and pore size was investigated, and the results indicated that improvement in hydrophilicity not only increased water flux itself, but also enabled high oil retention of membranes with larger pore sizes which had much higher water flux. The highest flux for the membranes with kerosene retention over 90% can reach over 300 L/m2h. The membranes showed good reusa...

Facile fabrication of hierarchical porous resins via high internal phase emulsion and polymeric porogen

Abstract To achieve the dual features of fast oil absorption rate and high oil absorbency for the practical application in emergency treatment of spilled chemical pollutants, hierarchical porous resins were synthesized. The polymerization of high internal phase emulsion was applied to fabricate the porous structure for the purpose of high oil absorbency. Polymeric porogens were proposed to adjust the second-order or interconnected pore structure for fast oil absorption rate. SEM revealed the hierarchical porous structure. Molecular weight and dose of polymeric porogen were investigated for the effect on the formation of porous structure and absorption features. Optimized resins have 31.5 g/g or 17.1 g/g absorbency for chloroform and toluene, respectively, and only 5 min is needed to reach their saturation absorption. Besides, the porous resins demonstrated high oil retention under pressure. The absorption/desorption cycling results revealed the high repeatability of recovered resins. All these tests predicted the potential applications of porous resins of this kind particularly in the emergency treatment of oil and chemical pollution.

Super-hydrophobic and Super-oleophilic Properties of Taro Leaves and Their Application

The super-hydrophobic and super-oleophilic properties of taro leaves and their application were reported.The reasons that taro leaves possess super-hydrophobic and super-oleophilic properties were analyzed by static contact angle(CA) and scanning electron microscopy(SEM).The saturated oil absorption rate,sustained release and centrifugal oil retention of taro leaves dried at different temperatures were measured and analyzed by weighing method,sustained release property and centrifugation etc.The results show that the reverse side of the taro leaf is super-hydrophobic and its static water contact angle can reach 157.1° which is much larger than that of the front one(109.1°),and the sliding angles are not larger than 3°.It is also observed that the change of saturated oil absorption rate for the taro leaves shows certain regularity,and the highest saturated oil absorption(8.1 g / g) was obtained while the taro leaves dried at 200 ℃.Taro leaves own different capacity on fixing various oil spill.It can be known from results that taro leaves have strong capacity on fixing low volatile oil material and high centrifugal oil retention at high rotate speed.

Fully Interconnected Porous Structure for Realization of Fast Oil-Absorption Resin

A fast oil-absorption resin with high pore level was developed by concentrated inverse emulsion polymerization. The oil absorption rate test displayed that only 30 min was needed for the resin to reach absorption saturation. The property was elucidated by the fully interconnected porous structure of the resins. Besides, resins exhibited high oil retention percentage in terms of fast centrifuge speed test and high reusability in terms of the repetitive absorption/desorption test. The effect of different polymerization parameters, such as the amount of initiator, cross-linker and emulsifier, on the oil absorbency was investigated in detail. The experimental results showed that the absorptive capacity of the resin was 8.5 g/g for toluene and 15.8 g/g for chloroform under the optimized conditions. All these features indicate wide practice applications.

Emulsion separation using hydrophobic grafted ceramic membranes by

Novel fluorosilanes grafted ceramic membranes were prepared and characterized in the air-gap membrane distillation (AGMD) process. The hydrophobic active layer was created by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane (C8 compound) on the ceramic membrane (mud of hydrocyclone laundries of phosphates/zirconia), to change their hydrophilic character into hydrophobic one. The efficiency of the grafting process was characterized by zirconia (SEM). The determination of the contact angle on the grafted membrane surface proved the hydrophobic character since it increases from 25° before grafting to values exceeding 160° after grafting. The membrane permeability varies from 720l/hm2 before grafting to 7l/hm2 after grafting. The new hydrophobic membrane seems to be promising in the field of membrane distillation. High salt and oil retention higher than 99% were obtained using modified MF ceramic membrane.

Dietary fiber from orange byproducts as a potential fat replacer

Brazil is the world's largest orange juice producer, but the waste that results from this process is a serious environmental problem. The purpose of this study was to characterize fibers from this byproducts and to study their application as a fat replacer in ice cream. Two different samples of orange fiber were analyzed: F1 (peel, pulp and seeds) and F2 (peel). Both samples showed high levels of total dietary fiber and an ideal ratio between soluble and insoluble fiber. The fibers showed a high water and oil retention capacity and a high content of phenolic compounds and carotenoids. The use of orange fiber as a fat replacer in ice cream led to a 70% reduction of fat without causing significant changes in products attributes such as color, odor and texture. Orange fiber proved to be a promising alternative as a fat replacer in ice cream production.

Effect of Homogenization Pressure and Oil Load on the Emulsion Properties and the Oil Retention of Microencapsulated Basil Essential Oil (Ocimum basilicum L.)

The objective of this work was to evaluate the influence of oil concentration and homogenization pressure on the emulsion and particle properties during the microencapsulation of basil essential oil by spray drying, using gum arabic as the wall material. Experiments were planned according a 22 rotational central composite design. The independent variables were oil concentration with respect to total solids (10–25%) and homogenization pressure (0–100 MPa). Emulsions were analyzed for droplet mean diameter, stability, and viscosity, and particles were analyzed for oil retention, moisture content, particle size, and morphology. Emulsion viscosity was not affected by any of the independent variables. The increase in the homogenization pressure from 0 to 100 MPa resulted in smaller emulsion droplet size (down to 0.40 µm) and, consequently, higher oil retention (up to 95%). On the other hand, higher oil loads (25%) resulted in poorer oil retention (51.22%). Microencapsulation of basil essential oil using gum arabic as the wall material proved to be a suitable process to obtain powdered basil essential oil, presenting great oil retention with the use of lower oil concentration and higher homogenization pressure.

β-Cyclodextrin-based oil-absorbent microspheres: Preparation and high oil absorbency

This article reports the preparation and evaluation of polymeric microspheres as a new class of oil-absorbent (POAMs). Based on our earlier oil-absorbents, the present microspheres contained β-cyclodextrin (β-CD) moieties as both cross-linking agent and porogen agent, and showed exciting high oil absorbency, fast oil absorption speed and good reusability. Such microspheres were prepared via suspension polymerization with octadecyl acrylate and butyl acrylate as co-monomers, β-CD derivative as cross-linking agent, 2,2′-azoisobutyronitrile as initiator and polyvinylalcohol as stabilizer. Oil absorbency of the POAMs was, for CCl4, 83.4; CHCl3, 75.1; xylene, 48.7; toluene, 42.8; gasoline, 30.0; kerosene 27.1; and diesel, 18.2g/g (oil/POAMs). Saturation oil absorption reached within 3h in CCl4. The POAMs exhibited high oil retention percentage (>90%), and can be reused for at least 10 times while keeping oil absorbency almost unchanged.

Preparation, structural and functional characterization of modified porous PVDF membranes by γ-irradiation

This work describes the synthesis of charged poly(vinylidene fluoride) (PVDF) membranes. Cationic membranes were prepared by graft modification using radiation-induced polymerization. Glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) were used as monomers and after graft polymerization the former was sulfonized with sodium sulfite. Membrane characterizations were carried out by FTIR-ATR, SEM-EDS, ionic exchange capacity, hydraulic permeability and liquid–liquid displacement. FTIR-ATR and SEM-EDS analysis revealed that increasing grafting degree increased the amount of the sulfonic group in the membranes. Sulfonated membranes showed smaller pore sizes and higher pore density than the original PVDF membrane. Oil/water ultrafiltration tests with the charged PVDF membranes showed interesting permselectivity performance; high oil retention values ( R > 98%), low chemical oxygen demand in the permeate solution (COD < 59 mg L −1). In addition, low fouling (<16.6%) and negligible irreversible fouling of the charged membranes was observed during the ultrafiltration tests.

Microencapsulation of Cajuput Oil by Spray Drying: Influence of Wall Systems on the Oil Retention and Storage

The microencapsulation of cajuput oil by spray drying was investigated with respect to the effects of two kinds of matrices (gum arabic and modified starch) as well as to the effects of initial concentrations of cajuput oil on its retention and stability. The results indicated that the oil retention depended on the type of encapsulating agent. Hicap100 showed higher oil retention of encapsulated cajuput oil. Further, the surface oil content of the Hicap100 powder was very low. The protective effect of microencapsulation of Hicap100 was also studied. The functional compound, 1,8-cineole, was released more slowly from the Hicap100 compared to gum arabic, especially at the level of 30% oil loaded.

Optimization of the Microencapsulation of Lemon Myrtle Oil Using Response Surface Methodology

Response surface methodology (RSM) was applied to study the effects of types of wall materials (modified starch + maltodextrin and whey protein concentrate + maltodextrin), feed concentration, oil concentration, and outlet air temperature on oil retention and surface oil content of the encapsulated powder. The results revealed that the oil retention was significantly (P < 0.05) affected by the constant term of types of wall materials and the linear term of feed concentration but seemed to be almost independent (P > 0.05) of experimental range of oil concentration and outlet air temperature. The types of wall materials, oil load, and outlet air temperature showed a significant (P < 0.05) influence on surface oil content. The types of wall materials (Hi-Cap and WPC) also influenced significantly the oil retention and surface oil content. Based on the limited range of experimental conditions used in this work, it was not possible to choose the wall materials that can give both high oil retention and low surface oil content. Disregarding the effect of wall material, an optimum response was obtained at 40% of feed concentration (w/w), 18% of oil concentration, and 65°C of outlet air temperature.