Fabrication of superhydrophilic and underwater superoleophobic quartz sand filter for oil/water separation

Intelligent Devices Harnessing Underwater Superoleophobic and Underoil Superhydrophobic Quartz Sands for the Separation of Diverse Stratified and Emulsified Water-Oil Mixtures

To achieve the green, sustainable, and controllable recovery of oil-water resources and to address the limited functionality of single superwet materials in oil-water separation, this study reports a multifunctional oil-water separation strategy by compositing the underwater superoleophobic and underoil superhydrophobic materials (HS). The underwater superoleophobic quartz sands with an oil contact angle of 152.68° were prepared by adjusting the particle size. This material demonstrated a water flux of 4688 L m-2 h-1 and a low-density oil and water mixture separation efficiency of 98.6%, which remained above 97.9% over 50 cycles. It was effective in separating oil-in-water emulsions with a separation efficiency of >99%. For HS, quartz sands were modified with dodecyltrimethoxysilane. The optimized HS-4 exhibited superhydrophobic properties with a water contact angle of 157.06°. It achieved an oil flux of 5775 L m-2 h-1 and a water and dichloromethane mixture separation efficiency of 98.4%. Additionally, they exhibited significant potential in the separation of water-in-oil emulsions. Furthermore, by placing the underwater superoleophobic and underoil superhydrophobic units at the bottom of the filter, we achieved cyclic separation of high-density oil and water mixtures, low-density oil and water mixtures, water-in-oil emulsions, and oil-in-water emulsions. The separation efficiency consistently exceeded 96.5% over 10 cycles. In addition, the oil-water separation mechanism of underwater oleophobic and underoil hydrophobic materials was demonstrated by the relative concentration distribution of water and oil with molecular dynamics simulations. This intelligent oil-water separation method marks a significant advancement in the sustainable separation of diverse oil-water mixtures.

Recent advances in superwetting materials for separation of oil/water mixtures

Engineering surfaces or membranes that allow an efficient oil/water separation is highly desired in a wide spectrum of applications ranging from oily wastewater discharge to offshore oil spill accidents. Recent advances in biomimetics, manufacturing, and characterization techniques have led to remarkable progress in the design of various superwetting materials with special wettability. In spite of exciting progress, formulating a strategy robust enough to guide the design and fabrication of separating surfaces remains a daunting challenge. In this review, we first present an overview of the wettability theory to elucidate how to control the surface morphology and chemistry to regulate oil/water separation. Then, parallel approaches are considered for discussing the separation mechanisms according to different oil/water mixtures, and three separation types were identified including filtration, adsorption and other separation types. Finally, perspectives on the challenges and future research directions in this research area are briefly discussed.

Textured ceramic membranes for desilting and deoiling of produced water in the Permian Basin

Oil production in the Permian Basin gives rise to large volumes of produced water contaminated by silt, emulsified oil, and additives used for enhanced oil recovery. There is intense interest in the design of membrane modules as sustainable alternatives for produced water treatment to enable the reuse of produced water for agricultural applications, injection into aquifers, and redeployment in oil recovery. Here, we report a hierarchically textured cement-based membrane exhibiting orthogonal wettability, specifically, superhydrophilic and underwater superoleophobic characteristics. The in situ formation of ettringite needles accompanied by embedding of glass spheres imbues multiscale texturation to stainless-steel mesh membranes, enabling the separation of silt and oil from produced water at high flux rates (1600 L h⁻¹۰m⁻², at ca. 2.7 bar). Oil concentration is reduced as low as 1 ppb with an overall separation efficiency of 99.7% in single-pass filtration. The membranes show outstanding mechanical resilience and retention of performance across multiple cycles.

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Multiscale 3D texturation of a metal mesh membrane engenders orthogonal wettability

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High separation efficiency of ca. 99% was achieved for produced water

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Oil concentration reduced to ≤1 ppb in a single pass at a high flux rate

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Desiliting and deoiling demonstrated for real produced water streams

A Materials Science Perspective of Midstream Challenges in the Utilization of Heavy Crude Oil

An increasing global population and a sharply upward trajectory of per capita energy consumption continue to drive the demand for fossil fuels, which remain integral to energy grids and the global transportation infrastructure. The oil and gas industry is increasingly reliant on unconventional deposits such as heavy crude oil and bitumen for reasons of accessibility, scale, and geopolitics. Unconventional deposits such as the Canadian Oil Sands in Northern Alberta contain more than one-third of the world's viscous oil reserves and are vital linchpins to meet the energy needs of rapidly industrializing populations. Heavy oil is typically recovered from subsurface deposits using thermal recovery approaches such as steam-assisted gravity drainage (SAGD). In this perspective article, we discuss several aspects of materials science challenges in the utilization of heavy crude oil with an emphasis on the needs of the Canadian Oil Sands. In particular, we discuss surface modification and materials' design approaches essential to operations under extreme environments of high temperatures and pressures and the presence of corrosive species. The demanding conditions for materials and surfaces are directly traceable to the high viscosity, low surface tension, and substantial sulfur content of heavy crude oil, which necessitates extensive energy-intensive thermal processes, warrants dilution/emulsification to ease the flow of rheologically challenging fluids, and engenders the need to protect corrodible components. Geopolitical reasons have further led to a considerable geographic separation between extraction sites and advanced refineries capable of processing heavy oils to a diverse slate of products, thus necessitating a massive midstream infrastructure for transportation of these rheologically challenging fluids. Innovations in fluid handling, bitumen processing, and midstream transportation are critical to the economic viability of heavy oil. Here, we discuss foundational principles, recent technological advancements, and unmet needs emphasizing candidate solutions for thermal insulation, membrane-assisted separations, corrosion protection, and midstream bitumen transportation. This perspective seeks to highlight illustrative materials' technology developments spanning the range from nanocomposite coatings and cement sheaths for thermal insulation to the utilization of orthogonal wettability to engender separation of water-oil emulsions stabilized by endogenous surfactants extracted during SAGD, size-exclusion membranes for fractionation of bitumen, omniphobic coatings for drag reduction in pipelines and to ease oil handling in containers, solid prills obtained from partial bitumen solidification to enable solid-state transport with reduced risk of damage from spills, and nanocomposite coatings incorporating multiple modes of corrosion inhibition. Future outlooks for onsite partial upgradation are also described, which could potentially bypass the use of refineries for some fractions, enable access to a broader cross-section of refineries, and enable a new distributed chemical manufacturing paradigm.

Robust and durable liquid-repellent surfaces

This review provides a comprehensive summary of characterization, design, fabrication, and application of robust and durable liquid-repellent surfaces.

In situ growth polydopamine decorated polypropylen melt-blown membrane for highly efficient oil/water separation

The removal of organic pollutants from water is highly desired because of the development of industrial and social economy. Superhydrophilic and underwater superoleophobic membranes are emerging materials for effective oil/water separation. In this paper, superhydrophilic and underwater superoleophobic polypropylene (PP) melt-blown membranes were prepared through melt-blown and in situ growth method, achieving highly efficient oil/water separation. After in situ growth, polydopamine (PDA) grows on the surface of PP fibers, and the addition of coupling agent (3-aminopropyltriethoxysilane, APTES) can improve the stability of the membrane in harsh environments (1 M HCl, 1 M NaOH, 1 M NaCl). The PDA/APTES@PP membrane could dramatically enhance the wetting (water contact angle ∼0, underwater oil contact angle∼154°) compare with the pristine PP melt-blown membrane (water contact angle ∼130°, underwater oil contact angle ∼0). Moreover, the filtration performance is at a high level (∼99%). The behaviors are comparable or even superior to the typical reported results in the references (such as the mussel-inspired superhydrophilic PVDF membrane and copper mesh). This method provides a facile route to prepared multi-functional membrane for highly efficiency oil/water separation and industrial oily wastewater remediation.

Controllable synthesis of in situ grown titanate hierarchical microspheres and subsequent chemical modifications for superhydrophobic and oil-water separation properties

Sodium titanate nanowire-assembled microspheres on titanium mesh have been synthesized through controlling an over the surface acidification and hydrothermal process in terms of a proposed in situ "nucleation-cum-growth" solution chemistry strategy. These directly grown microspheres crystallize in an orthorhombic lepidocrocite layered structure of sodium titanate with the composition of Na1.8Ti1.95□0.05O4.8 (□ ∼ vacancy) determined by the XRD, Raman and SEM-EDX techniques. An individual microsphere has a uniform size of around 10 microns while the constituent nanowires have a diameter of 100 nm growing along the [110] orientation. Owing to the specially well-defined hierarchical structure and robust in situ interfaces, these titanate nanowire-assembled microspheres, after 2,2,3,3,4,4,5,5-octafluoro-1-pentanol (OFP) surface modification, could achieve superhydrophobicity. This work demonstrates an in situ "nucleation-cum-growth" synthesis strategy and facile functionalization towards superhydrophobicity for oil-water separation, which might extend to a broad variety of oxide nanowire systems to fabricate well-defined structures for wettability tailoring and multi-functional applications.

Electrospinning on 3D Printed Polymers for Mechanically Stabilized Filter Composites

Electrospinning is a frequently used method to prepare air and water filters. Electrospun nanofiber mats can have very small pores, allowing for filtering of even the smallest particles or molecules. In addition, their high surface-to-volume ratio allows for the integration of materials which may additionally treat the filtered material through photo-degradation, possess antimicrobial properties, etc., thus enhancing their applicability. However, the fine nanofiber mats are prone to mechanical damage. Possible solutions include reinforcement by embedding them in composites or gluing them onto layers that are more mechanically stable. In a previous study, we showed that it is generally possible to stabilize electrospun nanofiber mats by 3D printing rigid polymer layers onto them. Since this procedure is not technically easy and needs some experience to avoid delamination as well as damaging the nanofiber mat by the hot nozzle, here we report on the reversed technique (i.e., first 3D printing a rigid scaffold and subsequently electrospinning the nanofiber mat on top of it). We show that, although the adhesion between both materials is insufficient in the case of a common rigid printing polymer, nanofiber mats show strong adhesion to 3D printed scaffolds from thermoplastic polyurethane (TPU). This paves the way to a second approach of combining 3D printing and electrospinning in order to prepare mechanically stable filters with a nanofibrous surface.