Oil/water separation is an important field, not only for scientific research but also for practical applications aiming to resolve industrial oily wastewater and oil-spill pollution, as well as environmental protection. Recently, research into the role of special wettability for oil/water separation has attracted much attention. In this review we summarize the design, fabrication, applications and recent developments of special wettable materials for oil/water separation. Based on the different types of separation, we organize this review into three parts: “oil-removing” type materials with superhydrophobicity and superoleophilicity (that selectively filter or absorb oil from oil/water mixtures), “water-removing” type materials with superhydrophilicity and superoleophobicity (that selectively separate water from oil/water mixtures), and smart controllable separation materials. In each section, we present in detail the representative work, introduce the design idea, outline their fabrication methods, and discuss the role of special wettability on the separation. Finally, the challenges and outlook for the future of this subject are discussed.

Special wettable materials for oil/water separation

In this work, we report the facile synthesis of hydrophobic, flexible, and ultralightweight (ρsponge ≤ 17.3 mg/cm3) nanocellulose sponges using a novel and efficient silylation process in water. These functional materials with high porosity (≥99%) are easily engineered by freeze-drying water suspensions of nanofibrillated cellulose (NFC), a natural nanomaterial isolated from renewable resources, in the presence of methyltrimethoxysilane sols of various concentrations. Microscopic and solid state nuclear magnetic resonance analyses reveal that the sponges are composed of a three-dimensional cellulosic network of thin sheets and nanofilaments, covered by polysiloxanes. Compared with conventional inorganic porous materials, the silylated NFC sponges display an unprecedented flexibility with a maximal shape recovery corresponding to 96% of the original thickness after 50% compression strain. The sponges also combine both hydrophobic and oleophilic properties and prove to be very efficient in removing dodecane...

Ultralightweight and Flexible Silylated Nanocellulose Sponges for the Selective Removal of Oil from Water

The development of a convenient method for the removal (or collection) of oils and organic solvents from water surface is of great significance for water environmental protection, especially for the cleanup of oil spillage on seawater. A major challenge is the fabrication of an oil absorber with high absorption capacity, low cost, scalable fabrication, high selectivity, and excellent recyclability. In this paper, we present a simple method for the removal and collection of oils and organic solvents from the surfaces of water based on superhydrophobic and superoleophilic sponges that were fabricated by solution-immersion processes. The as-prepared sponges fast and selectively absorbed various kinds of oils up to above 13 times the sponges’ weight while completely repelling water through a combination of porous, superhydrophobic, and superoleophilic properties. More interesting, the absorbed oils were readily collected by a simple mechanical squeezing process, and the recovered sponges could be reused in oi...

Facile Removal and Collection of Oils from Water Surfaces through Superhydrophobic and Superoleophilic Sponges

The Physics of Rubber Elasticity (J. Meixner)

Reduced graphene oxide coated polyurethane (rGPU) sponges were fabricated by a facile method. The structure and properties of these rGPU sponges were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, and scanning electron microscopy. The rGPU sponges are hydrophobic and oleophilic and show extremely high absorption for organic liquids. For all the organic liquids tested, the absorption capacities were higher than 80 g g–1 and 160 g g–1 (the highest value) was achieved for chloroform. In addition, the absorption capacity of the rGPU sponge did not deteriorate after it was reused 50 times, so the rGPU sponge has excellent recyclability.

Cost-Effective Reduced Graphene Oxide-Coated Polyurethane Sponge As a Highly Efficient and Reusable Oil-Absorbent

Ecological disasters resulting from oil spills have created a great need to find more efficient materials for oil spill cleanup This research highlights the use of a novel macroporous polymeric material based on butyl rubber (BR) as a sorbent in an oil spill cleanup The sorption capacity of BR for crude oil and petroleum products is 15−23 g g−1 as compared to the value of 10−16 g g−1 obtained using a nonwoven polypropylene (PP), a widely used commercial oil sorbent BR sorbent is reusable after simple squeezing and its continuous sorption capacity for crude oil is 76 g g−1 in each cycle, about 3 times the capacity of the PP sorbent BR sorbents also remove efficiently polycyclic aromatic hydrocarbons (PAHs) such as acenaphthene and pyrene from seawaters The results suggest that the rubber sorbents are a better alternative to the widely used PP sorbents by improving the efficiency of oil sorption and the reusability of the sorbent

https://web.itu.edu.tr/okayo/pdf/09est_supp.pdf

Evaluation of Butyl Rubber as Sorbent Material for the Removal of Oil and Polycyclic Aromatic Hydrocarbons from Seawater

https://web.itu.edu.tr/okayo/pdf/08polysaadet.pdf

Tough organogels based on polyisobutylene with aligned porous structures

The swelling behavior of balanced acrylam- ide (AAm)-based polyampholyte hydrogels in water and in aqueous salt (NaCl) solutions was investigated. Equi- molar ratio of the ionic comonomers 4-vinylpyridine (cati- onic monomer) and acrylic acid (anionic monomer) were used together with the nonionic monomer AAm in the hydrogel preparation. The variations of the hydrogel vol- ume in response to changes in pH were measured. It was found that the hydrogels are in a collapsed state not only at the pH of the isoelectric point pHIEP but also over a wide range of pH including pHIEP. The width of the collapsed pla- teau increased and the hydrogels assumed a more compact state as the ionic group content is increased. The antipolye- lectrolyte behavior was observed along the collapsed plateau region, where the gel occupies a larger volume in salt solu- tion. The experimental swelling data were compared with the predictions of the Flory-Rehner theory of swelling equi- librium including the ideal Donnan equilibria. V C 2009 Wiley

/pdf/collapse-of-acrylamide-based-polyampholyte-hydrogels-in-38laqkp4oh.pdf

Saadet Dogu

Papers

Evaluation of Butyl Rubber as Sorbent Material for the Removal of Oil and Polycyclic Aromatic Hydrocarbons from Seawater

Tough organogels based on polyisobutylene with aligned porous structures

Collapse of Acrylamide-Based Polyampholyte Hydrogels in Water