Hyper-Cross-Linked Polymer-Decorated Surfaces with Ultrahigh Efficiency for Oil/Water Emulsion Separation and Recovery

Regulation of Oil/Water Separation Using Pyridinium-Based Poly(ionic liquid)s with Prewetted Induced Responsive Transition

The development of affordable, intelligent dual-separation technology is crucial for the treatment of oil-water mixtures. Pyridinium-based poly(ionic liquid)s (PILs), designed using molecular theory, exhibit unique switching wettability properties, making them ideal for use in both aqueous and oily environments. By prewetting the material's surface with water or oil, the targeted separation of these components becomes feasible. PILs are synthesized through the cross-linking of [Pyr]Cl with various cross-linkers and auxiliary agents. Studies on the wetting mechanism of these materials have identified bursting pressure and surface structure as key factors influencing their wetting properties. They exhibit hydrophilic and lipophilic properties in air, hydrophobic properties under oil, and oleophobic properties under water, achieving a 99% separation efficiency. A reusability study demonstrated maintenance of 90% efficiency after 10 cycles, highlighting their sustained high performance. This research presents promising avenues for the application of PIL-based materials in oil-water separation, environmental remediation, and industrial processing.

A comprehensive review of fundamentals and future trajectories in oil-water separation system designs with superwetting materials

The rapid increase in the production of oily wastewater by industrial and daily activities, oil spill accidents, etc., has led to critical environmental issues. The solution to oil-induced pollution lies in developing efficient oil-water separation technologies. Recently, materials with extreme wettability, particularly those exhibiting superhydrophilic with superoleophobic or superhydrophobic with superoleophilic properties, have emerged as promising solutions for achieving highly efficient and selective oil-water separation. This review offers a comprehensive overview of system designs utilizing such materials for selective oil-water separation. Here, we discuss the rationale underlying the design strategy for the systems used for the separation process. Based on the broad scenarios utilizing oil-water separation, two primary groups of system designs are identified: those handling enclosed oil-water mixtures, such as treating oily wastewater before discharge, and those addressing open-to-air hypaethral oil-water mixtures, such as in the case of oil spills, oil on water bodies post oily wastewater discharge. The review traces the evolution of system designs from batch processing to continuous processing systems, identifies commonalities, and discusses the rationale and underlying design constraints. This analysis can guide the selection of appropriate systems for testing materials in oil-water separation and provides insights into future design development for further real-life deployment.

Advancing hyper-crosslinked materials with high efficiency and reusability for oil spill response

Developing materials with high efficiency for recovering oil to mitigate the environmental impact of oil spills has always been a challenging task. A commercial melamine formaldehyde sponge was coated with an optimised superhydrophobic/superoleophilic hyper-crosslinked polymer and applied to the removal of crude oil from oil-in-water emulsions for the improvement of oil spill clean-up processes. The high surface area, porosity, hydrophobicity, and selectivity of oil over water made the hyper-crosslinked polymer coated sponge (HPCS) an ideal sorbent for efficient oil/water separation. The system was able to strip crude oil from water emulsions of 1000 ppm to a negligible level of 2 ppm oil with minimal amounts of the HPCS material. More importantly, the HPCS material could be reused via a simple mechanical compression process, and the uptake capacity was retained over ten cycles. For five cycles of oil adsorption/mechanical compression the HPCS was able to provide water filtrate with oil concentrations of under 15 ppm. This is an effective and economical recovery system, removing the need for consistent solvent washing and drying processes. These results suggest that the HPCS is a promising material for oil/water separation and recovery under challenging conditions.

A solvent-template ethyl cellulose-polydimethylsiloxane crosslinking sponge for rapid and efficient oil adsorption

Lipophilic adsorbents for oil-water separation are usually synthesized using the template method, in which hydrophobic materials are coated on a ready-made sponge. Herein, a novel solvent-template technique is used to directly synthesize a hydrophobic sponge, by crosslinking polydimethylsiloxane (PDMS) with ethyl cellulose (EC) which plays a vital role in the formation of 3D porous structure. The as-prepared sponge has advantages of strong hydrophobility, high elasticity, as well as excellent adsorption performance. In addition, the sponge can be readily decorated by nano-coatings. After the sponge was simply dipped in nanosilica, the water contact angle increases from 139.2° to 144.5°, and the maximum adsorption capacity for chiroform rises from 25.6 g/g to 35.4 g/g. The adsorption equilibrium can be reached within 3 min, and, the sponge can be regenerated by squeezing, without any change in hydrophobility or evident decline in capacity. The simulation tests of emulsion separation and oil-spill cleanup demonstrate that the sponge has great potential in oil-water separation.

Blood-Coagulation-Inspired Dynamic Bridging Strategy for the Fabrication of Multiscale-Assembled Hierarchical Porous Material

Porous materials, from macroscopic bulk materials (MBs) with (sub-)millimeter-scale pores to tiny particles (TPs) with (sub-)nanometer-scale pores, have attracted ever-growing interest in various fields. However, the integration of multi-scale pores in one composite is promising but challenging, owing to the considerable gap in the scale of the pores. Inspired by blood coagulation, a fibrin-based dynamic bridging strategy is developed to fabricate a multiscale-assembled hierarchical porous material (MHPM), in which fibrin formed as the sub-framework for the weaving-narrow of MBs and the enwinding-load of TPs. The bio-polymerization nature makes the fabrication rapid, facile, and universal for the customizable integration of seven kinds of TPs and four kinds of MBs. Besides, the integration is controllable with high load capacity of TPs and is stable against external shock forces. The unique multi-level structure endows the MHPM with large and accessible surface area, and efficient mass transfer pathways, synergistically leading to high adsorption capacity and rapid kinetics in multiple adsorption models. This work suggests a strategy for the rational multi-level design and fabrication of hierarchical porous architectures.

Recent Advances in Functional Materials for Wastewater Treatment: From Materials to Technological Innovations

The growing concerns about climate changes and environmental pollution have galvanized considerable research efforts in recent years to develop effective and innovative remediation technologies for contaminated soils and water caused by industrial and domestic activities. In this context, the establishment of effective treatment methods for wastewater has been critically important and urgent, since water pollution can take place on a very large scale (e.g., oceanic oil spills) and have massive impacts on ecosystems and human lives. Functional materials play a central role in the advancement of these technologies due to their highly tunable properties and functions. This article focuses on reviewing the recent progress in the application of various functional materials for wastewater treatment. Our literature survey is first concentrated on new modification methods and outcomes for a range of functional materials which have been actively investigated in recent years, including biofilm carriers, sand filters, biomass, biopolymers, and functional inorganic materials. Apart from the development of modified functional materials, our literature survey also covers the technological applications of superhydrophilic/superhydrophobic meshes, hybrid membranes, and reusable sponges in oil–water separation. These devices have gained significantly enhanced performance by using new functional materials as the key components (e.g., coating materials), and are therefore highly useful for treatment of oily wastewater, such as contaminated water collected from an oil spill site or oil–water emulsions resulting from industrial pollution. Based on our state-of-the-art literature review, future directions in the development and application of functional materials for wastewater treatment are suggested.