Durable superhydrophobic cotton fabric for oil/water separation

Silane and fluorine free facile hydrophobicization of water hyacinth biomass for oil-water separations

As the adverse effects of using plastics and perfluorinated alkyl substances become more apparent, there is a growing need for sustainable hydrophobic products. Cellulose and its derivatives are the most abundant and widely used polymers, and cellulose-based products have great potential in industries where plastics and other hydrophobic polymers are used, such as stain-resistant fabrics, food packaging, and oil-water separation applications. In this study, we extracted cellulose from water hyacinth (WH) biomass, known for its negative environmental impact, and converted it into hydrophobic cellulose. This addresses the issue of managing WH waste and creating an environmentally friendly hydrophobic material. Initially, aldehyde groups were introduced through oxidation with periodate, followed by direct octadecyl amine (ODA) grafting onto dialdehyde cellulose (DAC) via a Schiff base condensation. The resulting ODA modified cellulose (ODA-C) was dispersed in ethanol and used to coat various materials, including cotton fabric, cellulose filter paper, and packaging paper. The modified materials showed excellent hydrophobicity as measured by their water contact angles (WCAs), and the application of the coating was demonstrated for oil-water separation, stain-resistant hydrophobic fabric, and paper-based packaging materials. FTIR, XRD, and WCA analysis confirmed the successful modification of cellulose. A high separation efficiency of 99% was achieved for diesel/water separation using modified filter paper (MoFP), under gravity. On application of the coating, cotton fabric became hydrophobic and resisted staining from dye, and paper-based packaging materials became more robust by becoming water-resistant. Overall, the facile synthesis, low cost, high efficiency, and use of environmentally friendly sustainable materials make this a promising strategy for hydrophobically modifying surfaces for a wide range of applications while reducing the menace of water hyacinth.

A One-Step Approach for a Durable and Highly Hydrophobic Coating for Flax Fabrics for Self-Cleaning Application

Highly hydrophobic flax fabrics with durable properties were prepared using the "dip-coating" method for self-cleaning application. Flax fabrics were coated with a polysiloxane coating via a hydrosilylation reaction with a Karstedt catalyst at room temperature. The coated fabrics displayed highly and durable hydrophobic properties (contact angle and sliding angle of about 145° and 23°, respectively) with good self-cleaning ability for certain pollutants and excellent durability. Moreover, the influence of the coating process on the mechanical properties of fabrics was investigated. A decrease in E modulus and an increase in tensile stress at maximum force and elongation at maximum force has been observed. Furthermore, this influence of the coating process can be easily controlled by adjusting the proportion of curing agent in the treatment solution.

Polyphenylene Sulfide Ultrafine Viscous Fibrous Membrane Modified by ZIF-8 for Highly Effective Oil/Water Separation under High Salt or Alkaline Conditions

The oil/water separation in harsh environments has always been a challenging topic all over the world. In this study, the ZIF-8/PPS fiber membranes were fabricated via the combination of hot pressing and in situ growth. The distribution of ZIF-8 in the membranes was adjusted by changing the ZIF-8 in situ growth time, which could control the oil/water separation effect. Due to the hydrophilic nature of the ZIF-8/PPS fiber membranes, the water molecules in the oil-in-water emulsion could quickly penetrate into the fiber membrane under the drive of pressure, gravity, and capillary force, forming a water layer on the surface of the fiber membranes. The coupling of the water layer and the fiber structure prevented direct contact between the oil molecules and the fiber membrane, thereby realizing the separation of the emulsion. The results show that when the ZIF-8 in situ growth time was 10 h, the contact angle, the porosity, and the pure water flux of the ZIF-8/PPS fiber membranes were 72.5°, 52.3%, and 12,351 L/h·m², respectively. More importantly, the separation efficiency of M10 was 97%, and the oil/water separation efficiency reached 95% after 14 cycles. This study provides a novel strategy for preparing MOFs/fiber materials for oil/water separation in harsh environments.

Superhydrophobic magnetic sorbent via surface modification of banded iron formation for oily water treatment

In the current study, a simple dry coating method was utilized to fabricate a super-hydrophobic super-magnetic powder (ZS@BIF) for oily water purification using zinc stearate (ZS) and banded iron formation (BIF). The produced composite was fully characterized as a magnetic sorbent for oily water treatment. The results of X-ray diffraction diffractometer (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and particle size analysis revealed the fabrication of homogenous hydrophobic-magnetic composite particles with core–shell structure. Contact angle and magnetic susceptibility results showed that 4 (BIF): 1 (Zs) was the ideal coverage ratio to render the core material superhydrophobic and preserve its ferromagnetic nature. The capability of the fabricated composite to sorb. n-butyl acetate, kerosene, and cyclohexane from oil–water system was evaluated. ZS@BIF composite showed a higher affinity to adsorb cyclohexane than n-butyl acetate and kerosene with a maximum adsorption capacity of about 22 g g⁻¹ and 99.9% removal efficiency. Moreover, about 95% of the adsorbed oils could be successfully recovered (desorbed) by rotary evaporator and the regenerated ZS@BIF composite showed high recyclability over ten repeated cycles.

Cellulose-based special wetting materials for oil/water separation: A review

Oil spill accidents and oily wastewater discharged by petrochemical industries have severely wasted water resources and damaged the environment. The use of special wetting materials to separate oil and water is efficient and environment-friendly. Cellulose is the most abundant renewable resource and has natural advantages in removing pollutants from oily wastewater. The application and modification of cellulose as special wetting materials have attracted considerable research attention. Therefore, we summarized cellulose-based superlipophilic/superhydrophobic and superhydrophilic/superoleophobic materials exhibiting special wetting properties for oil/water separation. The treatment mechanism, preparation technology, treatment effect, and representative projects of oil-bearing wastewater are discussed. Moreover, cellulose-based intelligent-responsive materials for application to oil/water separation and the removal of other pollutants from oily wastewater have also been summarized. The prospects and potential challenges of all the materials have been highlighted.

Preparation of superhydrophobic nylon-56/cotton-interwoven fabric with dopamine-assisted use of thiol-ene click chemistry

With the help of dopamine, we constructed a hydroxyl-rich secondary reaction platform on a surface formed by interwoven nylon 56 and cotton fibres. Octadecyl mercaptan and vinyl trimethoxysilane (VTMS) are used for the click coupling preparation of superhydrophobic reagents, which are grafted onto polydopamine aggregates and successfully used to prepare superhydrophobic nylon 56/cotton-interwoven fabric. The static contact angle was 161° and the sliding angle was 8°. Note that the prepared superhydrophobic fabric can withstand corrosive liquids, water washing, ultraviolet radiation and mechanical abrasion, it has excellent superhydrophobic stability, and self-cleaning and oil–water-separation functionalities. This simple, fast and environmentally friendly method can be applied to other substrates and shows tremendous potential for expanding the field of superhydrophobic applications.

Preparation process of superhydrophobic textiles.

Facile preparation of robust superhydrophobic cotton fabric for ultrafast removal of oil from contaminated waters

A new class of robust superhydrophobic cotton fabric was prepared by chemically grafting method for removing oil from contaminated waters. Furthermore, the mechanical, chemical, and thermal durability of superhydrophobic cotton fabric was evaluated in detail. The superhydrophobic cotton fabric did not only showed excellent separation efficiency (ca.100%) and ultrafast separation rate (ca. 13,600 L/h m²) but also exhibited excellent durability. Especially, the oil/water separation rate was almost 10 times than that reported in previous works. The work provides a new method to design and large-scale prepare oil/water separation materials with high performance for industrial use.

Progress in Sol-Gel Technology for the Coatings of Fabrics

The commercial availability of inorganic/organic precursors for sol-gel formulations is very high and increases day by day. In textile applications, the precursor-synthesized sol-gels along with functional chemicals can be deposited onto textile fabrics in one step by rolling, padding, dip-coating, spraying or spin coating. By using this technology, it is possible to provide fabrics with functional/multi-functional characteristics including flame retardant, anti-mosquito, water- repellent, oil-repellent, anti-bacterial, anti-wrinkle, ultraviolet (UV) protection and self-cleaning properties. These surface properties are discussed, describing the history, basic chemistry, factors affecting the sol-gel synthesis, progress in sol-gel technology along with various parameters controlling sol-gel technology. Additionally, this review deals with the recent progress of sol-gel technology in textiles in addressing fabric finishing, water repellent textiles, oil/water separation, flame retardant, UV protection and self-cleaning, self-sterilizing, wrinkle resistance, heat storage, photochromic and thermochromic color changes and the improvement of the durability and wear resistance properties.

Surface Modification of Cotton Fabric Using TiO2 Nanoparticles for Self-Cleaning, Oil-Water Separation, Antistain, Anti-Water Absorption, and Antibacterial Properties

Superhydrophobicity is of interest for practical applications such as water repellency, self-cleaning, stain resistance, antibacterial properties, and oil-water separation. In this work, a superhydrophobic coating on cotton fabric is prepared by simple immersion in TiO₂ nanoparticles and perfluorodecyltriethoxysilane solution. Its antiwetting properties, surface morphology, and functionality are characterized. The cotton fabric shows superhydrophobicity with a water static contact angle of 169.3 ± 2.1° and tilt angle of 6.3 ± 2.0°. The coating is also characterized by performing stability tests, and it shows excellent mechanical durability, chemical stability, and thermal stability. Additionally, the water droplet dynamic on the coated surface is also studied. The coated cotton fabric exhibits excellent self-cleaning, stain resistance, rust stain resistance, anti-water absorption, and antibacterial properties. It can also be used in oil-water separation with a high separation efficiency and excellent reusability.

Highly Hydrophobic Cotton Fabrics Modified by Poly(methylhydrogen)siloxane and Fluorinated Olefin: Characterization and Applications

Highly hydrophobic cotton fabrics were obtained with poly(methylhydrogen)siloxane (PMHS) and a further fluorinated olefin modification. The chemical structures and microstructures of PMHS-modified cotton fabrics were characterized, and application of the resultant cotton fabrics in stain resistance and oil–water separation was demonstrated. PMHS chains with very low surface energy were grafted onto cotton fabric by the dehydrogenation reaction between –Si–H of PMHS and –OH groups of cotton fabric at room temperature. The water contact angle of PMHS-modified cotton fabric was 141.7°, which provided the modified cotton fabric with good stain resistance to waterborne pollutants. The separation efficiency of diesel from water was higher than 92% for 20 repeatable separation cycles. A further improvement in stain resistance to oil was also demonstrated by a further addition reaction of 1H,1H,2H-perfluoro-1-decene with PMHS-modified cotton fabric.

In-Situ Synthesis of Hydrophobic Polyurethane Ternary Composite Induced by Hydroxyethyl Cellulose through A Green Method for Efficient Oil Removal

Hydroxyethyl cellulose (HEC) was introduced to activate the surface of polyurethane (PU) sponge to successfully prepare a hydrophobic ternary composite PU/HEC/SiO₂. The hydrophobic layer of the composite was realized by in-situ polymerization of methyltriethoxysilane (MTES) onto the surface of PU sponge. The formation of a stable hydrophobic SiO₂ layer solved successfully the problem of ease of SiO₂ particles shedding from the composite. Moreover, the amphiphilic molecules produced by the hydrolysis of MTES monomers facilitated the preparation of hydrophobic materials by aqueous dispersion polymerization. Aqueous synthesis made the reaction process environmentally-friendly and pollution-free. The as-prepared composite PU/HEC/SiO₂ not only retains high porosity and low density of the PU sponge, but also considerably reduced the surface free energy and increased the surface roughness of the PU sponge. Therefore, outstanding hydrophobicity and high porosity endow the composite with excellent oil removal capability as a high-efficiency absorbent. Moreover, the hydrophobic composite that had absorbed oil could be regenerated easily by squeezing and recycling.

Recent Advances in Femtosecond Laser-Induced Surface Structuring for Oil–Water Separation

Femtosecond (FS) laser-induced surface structuring is a robust, maskless, non-contact, and single-step process for producing micro- and nanoscale structures on a material’s surface, which remarkably alters the optical, chemical, wetting, and tribological properties of that material. Wettability control, in particular, is of high significance in various applications, including self-cleaning, anti-fouling, anti-icing, anti-corrosion, and, recently, oil–water separation. Due to growing energy demands and rapid industrialization, oil spill accidents and organic industrial discharges frequently take place. This poses an imminent threat to the environment and has adverse effects on the economy and the ecosystem. Oil–water separation and oil waste management require mechanically robust, durable, low-cost, and highly efficient oil–water manipulation systems. To address this challenge superhydrophobic–superoleophilic and superhydrophilic–underwater superoleophobic membrane filters have shown promising results. However, the recyclability and durability issues of such filters are limiting factors in their industrial application, as well as in their use in oil spill accidents. In this article, we review and discuss the recent progress in the application of FS laser surface structuring in producing durable and robust oil–water separation membrane filters. The wide variety of surface structures produced by FS laser nano- and micromachining are initially presented here, while the excellent wetting characteristics shown by specific femtosecond-induced structures are demonstrated. Subsequently, the working principles of oil–water separation membranes are elaborated, and the most recent advances in the topic are analyzed and discussed.

Cost-Effective, Highly Selective and Environmentally Friendly Superhydrophobic Absorbent from Cigarette Filters for Oil Spillage Clean up

Ecological and environmental damage caused by oil spillage has attracted great attention. Used cigarette filters (CF) have also caused negative environmental consequences. Converting CF to economical materials is a feasible way to address these problems. In this study, we demonstrate a simple method for production of a highly hydrophobic absorbent from CF. CF was modified by using different volume ratios of octadecyltrichlorosilane and methyltrimethoxysilane. When the volume ratio was 3:2, the modified CF had the high water contact angle of 155°. It could selectively and completely absorb silicone oil from an oil-water mixture and showed a good absorption capacity of 38.3 g/g. The absorbed oil was readily and rapidly recovered by simple mechanical squeezing, and it could be reused immediately without any additional treatments. The as-obtained superhydrophobic modified CF retained an absorption capacity of 80% for pump oil and 82% for silicone oil after 10 cycles. The modified CF showed good elasticity in the test of repeated use. The present study provides novel design of a functional material for development of hydrophobic absorbents from used CF via a facile method toward oil spillage cleanup, as well as a new recycling method of CF to alleviate environmental impacts.

Fabrication of Durably Superhydrophobic Cotton Fabrics by Atmospheric Pressure Plasma Treatment with a Siloxane Precursor

The surface treatment of fabrics in an atmospheric environment may pave the way for commercially viable plasma modifications of fibrous matters. In this paper, we demonstrate a durably superhydrophobic cotton cellulose fabric prepared in a single-step graft polymerization of hexamethyldisiloxane (HMDSO) by N₂ and O₂ atmospheric pressure plasma. We systematically investigated effects on contact angle (CA) and surface morphology of the cotton fabric under three operational parameters: precursor value; ionization gas flow rate; and plasma cycle time. Surface morphology, element composition, chemical structure and hydrophobic properties of the treated fabric were characterized by scanning electron microscope (SEM), EDS, FTIR and CA on the fabrics. The results indicated that a layer of thin film and nano-particles were evenly deposited on the cotton fibers, and graft polymerization occurred between cellulose and HMDSO. The fabric treated by O₂ plasma exhibited a higher CA of 162° than that treated by N₂ plasma which was about 149°. Furthermore, the CA of treated fabrics decreased only 0°~10° after storing at the ambient conditions for four months, and treated fabrics could also endure the standard textile laundering procedure in AATCC 61-2006 with minimum change. Therefore, this single-step plasma treatment method is shown to be a novel and environment-friendly way to make durable and superhydrophobic cotton fabrics.

Superhydrophobic/superoleophilic cotton-oil absorbent: preparation and its application in oil/water separation

A superhydrophobic and superoleophilic oil sorbent was prepared by attaching SiO₂ particles onto a cotton fiber surface by a sol–gel method and subsequent octadecyltrichlorosilane modification. The surface formation was confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, and an observation of the water behavior on the cotton surface. The sorption capacity of the modified cotton in pure oil and in an oil/water mixture, the oil adsorption and the reusability were investigated. Compared with raw cotton, the as-prepared cotton absorbed different oils rapidly up to in excess of 25–75 g g⁻¹ its own weight, and the water adsorption was nearly 0 g g⁻¹. The modified cotton fiber could separate oil/water mixtures efficiently through a flowing system. After 10 cycles, the as-prepared cotton was still highly hydrophobic with a 6-times greater adsorption than raw cotton. By a simple modification, a low-cost, high-adsorption and environmentally friendly modified cotton could be prepared that can be considered a promising alternative to organic synthetic fibers to clean up oil spills.

A superhydrophobic and superoleophilic oil sorbent was prepared by attaching SiO₂ particles onto a cotton fiber surface by a sol–gel method and subsequent octadecyltrichlorosilane modification.