Oleophilic Nature Research Articles

Preparation of magnetic hydrophobic polyvinyl alcohol (PVA)–cellulose nanofiber (CNF) aerogels as effective oil absorbents

Efficient, rapid removal of oil spills on the surface of water is technologically significant for protecting the ecological marine environment. In this work, environmentally friendly, novel, magnetic hydrophobic PVA/CNF aerogels (MHPCA) with ultralow density (13.84 kg m−3), high porosity (> 98%), magnetic responsivity and good mechanical properties were successfully prepared by vacuum freeze-drying PVA/CNF gel followed by a facile silanization reaction and dipping process. The hydrophobic but oleophilic nature of the as-prepared MHPCA (water contact angle over 138°) came from the polysiloxane coated on the fiber surface by the silanization reaction. The MHPCA had excellent oil/water selectivity, with oil absorption capacity as high as 136 g/g being observed. Additionally, the MHPCA exhibited good magnetic response and could absorb oil on the surface of water by magnetic driving. More importantly, the MHPCA showed excellent elasticity after 30 compression-release cycles, which demonstrated the reusability and durability of the super absorbent. The results of this work provide a feasible idea for easily and efficiently removal of oil pollution from the water surface.

One‐Step Approach to the Growth of ZnO Nano‐/Microrods on Cellulose toward Its Durable Superhydrophobicity

Superhydrophobic surfaces have aroused great attention to fundamental and scientific researches. However, they have poor durability when they are exposed to a condition of high temperature or external forces. Herein, a durable superhydrophobic cellulose film against extreme high temperature and mechanical force is reported. ZnO nano‐ and microrods are constructed on cellulose using an effective, simple, and environmentally benign one‐step hydrothermal method without any crystal seeds or morphology controlling agents. After being modified with stearic acid, the cellulose film becomes superhydrophobic with a static contact angle of 154.1° and rolling angle of 6.9°. The superhydrophobic cellulose film shows excellent water‐repellent property even under dynamic water pressure, while it exhibits oleophilic nature under water, which can solve water pollution caused by heavy oil residuals. It is further found that it displays durable superhydrophobicity even if heated at 200 °C for 1 h or strongly scratched by knife. And heat treated films have better stability of superhydrophobicity under extreme condition with pH region from 3 to 11. These properties facilitate its applications of harsh conditions.

Green technological approach to synthesis hydrophobic stable crystalline calcite particles with one-pot synthesis for oil–water separation during oil spill cleanup

The process of separating oil and water from oil/water mixtures is an attractive strategy to answer the menace caused by industrial oil spills and oily wastewater. In addition, water coproduced during hydrocarbon exploitation, which can be an economic burden and risk for freshwater resources, can become an important freshwater source after suitable water-oil separation. For oil-water separation purposes, considerable attention has been paid to the preparation of hydrophobic-oleophilic materials with modified surface roughness. However, due to issues of thermodynamic instability, costly and complex methods as well as lack of ecofriendly compounds, most of hydrophobic surface modified particles are of limited practical application. The study presents a facile procedure, to synthesize crystalline particles of calcite, which is the most stable polymorph of CaCO3 from industrial CaCO3 using oleic acid as an additive in a one-pot synthesis method. The XRD results show that the synthesized particles were a well-crystallized form of calcite. The FTIR results reflect the appearance of the alkyl groups from the oleic acid in synthesized particles which promotes the production of calcite with ‘rice shape’ (1.64 μm) (aggregated by spherical nanoparticle of 19.56 nm) morphology with concomitant changes in its surface wettability from hydrophilic to hydrophobic. The synthesized particles exhibited near to super hydrophobicity with ∼99% active ratio and a contact angle of 143.8°. The synthesized hydrophobic calcite particles had an oleophilic nature where waste diesel oil adsorption capacity of synthesized calcium carbonate (HCF) showed a very high (>99%) and fast (7 s) oil removal from oil-water mixture. The functional group of long alkyl chain including of CO bounds may play critical roles for adsorption of diesel oils. Moreover, the thermodynamically stable crystalline polymorph calcite (compared to vaterite) exhibited excellent recyclability. The isothermal study reflects the comparatively high value of correlation coefficient (R2 = 0.94) for the Langmuir isotherm compared to those of the Freundlich isotherm (R2 = 0.82) showed that the adsorption of diesel oil onto the hydrophobic CaCO3 adsorbent was much better described by the Langmuir isotherm. The kinetics study of second-order rate expression (R2 = 0.99) more fitted with the experimental data compare to first-order model (R2 = 0.92). The synthesized calcite exhibited a significant dual oleophilic and hydrophobic nature that can be applicable for oil adsorption/or removal purpose in oil contaminated areas in environment and/or industrial oily wastewater for green, simple, and inexpensive environmental cleanup.

Axillary odour studies on alkali-treated knitted polyester fabric

PurposeOdour formation in textile material is mainly based on the fibre content and also the constituent fibres’ chemical and physical structures. Polyester fibre materials are very profound to form odour after being worn due to their highly oleophilic nature. The purpose of this paper is to analyse the odour formation characteristics of polyester fabric after surface modification through alkali treatment.Design/methodology/approachFive male participants were allowed to use the alkali-treated and untreated polyester fabrics, which were fixed in the axilla region of their vest. Subjective and objective odour analyses were performed for the worn samples. The odour was evaluated in terms of intensity rating, bacterial population (CFU/ml) and bacterial isolation.FindingsThe results showed that alkali treatment was effective in odour reduction in polyester fabric (p<0.005). The bacterial population density was also reduced significantly (p<0.005) in the alkali-treated polyester fabric compared to the untreated polyester fabric after the wear trial. The alkali treatment affected the surface structure of the polyester fabric and thus changed it from hydrophilic to hydrophobic. This was confirmed by the moisture management test results.Originality/valueThe odour formation in the polyester fabric can be controlled by simple surface modification process like alkali treatment, and thus the value of the product can be increased in the apparel sector.

Multifunctional superamphiphobic fabrics with asymmetric wettability for one-way fluid transport and templated patterning

In this work, multifunctional superamphiphobic fabrics with special wettability were constructed by a facile dip-coating or electrospraying process using easily available materials, viz. silica nanoparticles, heptadecafluorononanoic, and fluoroalkyl silane. The obtained HFA–FAS–SiO2 NPs@surface exhibited a contact angle (CA) of 166.4 ± 3.7° and 155.9 ± 2.1° to water and hexadecane, respectively. In addition, this surface also showed stable repellency toward various corrosive droplets at a wide range of pH values, including HCl (pH = 1), NaCl (pH = 7), and NaOH (pH = 14) solutions. After immersion in the strong acid and base solutions for 24 h, the cotton surface still maintained excellent anti-wetting property. The surface was durable enough to withstand 120 cycles of abrasion and 5 cycles of accelerated standard laundry and still kept a water CA higher than 140° and an oil CA higher than 120°. Another treatment method adopted in this work, electrospraying has been proved to be able to realize asymmetric wetting with one side displaying highly anti-wetting behavior and the other side retaining the inherent hydrophilic and oleophilic nature of the pristine cotton fabric. Based on this special wettability, the obtained fabric could display a one-way directional transport feature. This method can also be extended to create hydrophilically and oleophilically patterned superamphiphobic cotton fabrics using a template. This novel fabric is useful for the development of intelligent cellulose-based substrates for various applications.

CNTs reinforced super-hydrophobic-oleophilic electrospun polystyrene oil sorbent for enhanced sorption capacity and reusability

To meet the challenges of global oil spills and oil-water contamination, the development of low-cost and reusable sorbents with good hydrophobicity and oleophilic nature is crucial. In this study, functionalized carbon nanotubes (CNTs) were wrapped in polystyrene (PS) polymer (PS-CNTs) and electrospun to create an effective and rigid sorbent for oil. Covalent modification and fluorination of CNTs improved their dispersibility and interfacial interaction with the polymer, resulting in a well-aligned CNTs configuration inside the porous fiber structure. Interestingly, the oil sorption process using PS-CNTs was observed to have two phases. First, the oil swiftly entered the membrane pores formed by interconnected nanofibers due to oleophilic properties of the micro-sized void. In the second phase, the oil not only moved to nano interior spaces of the fibers by capillary forces but also adsorbed on the surface of fibers where the latter was retained due to Van der Waals force. The sorption process fits well with the intra particle diffusion model. Maximum oil sorption capacity of the PS-CNTs sorbent for sunflower oil, peanut oil, and motor oils were 116, 123, and 112g/g, respectively, which was 42–70% higher than that of the PS sorbent without CNTs. Overall, a significant increase in the porosity, surface area, water contact angle, and oleophilic nature was observed for the PS-CNTs composite sorbents. Not only did the PS-CNTs sorbents exhibited a promising oil sorption capacity but also showed potential for reusability, which is an important factor to be considered in determining the overall performance of the sorbent and its environmental impacts.

Fabrication of highly amphiphobic paper using pulp debonder

As a biodegradable, inexpensive and universally accessible material, paper is used widely in many applications, including packaging, office supplies and household products. However, the hydrophilic and oleophilic nature of paper often limits its use in applications that involve direct contact with liquids. The main purpose of this study was to create highly amphiphobic paper for products such as low cost medical testing strips, liquid packaging, and breathable and disposable medical apparel. A three-step process was developed to create paper with contact angles greater than 150° for water and motor oil, and greater than 140° for n-hexadecane. First, a commercially available debonding agent was used to manipulate the dimensions of the fiber network through efficient fines removal and modification of inter-fiber hydrogen bonding. Then an oxygen plasma was used to create nano-scale roughness on the micrometer-sized fibers and to remove residual fines that were blocking the inter-fiber pores. Finally, the paper was immersed in a fluorosilane solution to obtain a thin, low surface energy coating. XPS, SEM, mercury porosimetry and profilometry were used to evaluate changes in the fiber network after each step. This study marks the first report that uses debonder agents specifically to modify the anti-wetting properties of paper substrates by controlling the topology of the fiber network. The processes used in this procedure are simple, cost effective and amenable to scale-up.

Superhydrophobic and oleophilic barium sulfate material for oil spill clean-ups: Fabrication of surface modified sorbent by a one-step interaction approach

Oil spill in ocean is considered to be a serious problem for the environmental scientists, since monitoring and cleaning processes are difficult in the dynamic ocean system. Out of many approaches adopted by different scientific groups, development of cheaper, eco-friendly and re-usable sorbent materials possessing sufficient buoyancy, good selectivity and high rate of uptake has drawn great attention. In the present study, superhydrophobic and oleophilic barium sulfate sorbent powder (water contact angle 152±1°) were prepared by surface modification of pure barium sulfate with palmitic acid in a one-step interaction approach, and characterized by XRD, FT-IR, and SEM. The hydrophobic and oleophilic nature of the fabricated powder was confirmed by various laboratory experiments and contact angle measurements. The powder also possesses high selectivity towards oil and sufficient buoyancy to serve as a potential candidate for oil spill clean-ups. Further, the reusability experiments show that the as-prepared sorbent material is reusable for minimum three times for oil sorption.

Investigation of Oleophilic Nature of Straw Sorbent Conditioned in Water

Absorptive potential of barley straw conditioned in water with respect to the properties of interior and exterior surface of the stalk and leaf is discussed. The contact angle for water and decane, both on dry and wet straw was measured. The internal and external surface of the stalk as well as of the leaf remained preferentially oleophilic when dry, regardless of the straw decomposition time. In the case of straw conditioned in water the external stalk surface exhibited oleophilic properties for 10 days whereas that of the leaf for seven days. During decomposition a wax layer on epidermis was removed. Decreasing accuracy of contact angle determination after 14 days of decomposition was caused by growth of microorganisms on the straw surface.

Studies of Detergency. XIII.

The soil removal efficiencies have been studied from the view of hydrophilic or oleophilic nature of surfactants, soil, and fabrics.In the case of washing by the detergent that is mainly formulated with LAS, the detergency depends on water hardness. The water hardness dependencies on the detergency for the hydrophilic fabrics such as cotton and nylon are comparatively small, but are great for the oleophilic fabrics such as wool, and consequently the maximum detergency is observed at a some water hardness.The water hardnesses corresponding to the maximum detergency depend on the polarity of soils adhered on fabric and increase with the increase of the polarity of soil.In the case of washing by the detergents that are mainly formulated with non-ionic surfactants, the dependency of detergency on the HLB of the surfactants is little for the hydrophilic fabrics such as cotton, but is great for the oleophilic fabrics such as wool.