Graphene-based materials can be potentially utilized for separation membranes due to their unique structural properties such as precise molecular sieving by interlayer spacing or pore structure and excellent stability in harsh environmental conditions. Therefore, graphene-based membranes have been extensively demonstrated for various water treatment applications, including desalination, water extraction, and rare metal ion recovery. While most of the utilization has still been limited to the laboratory scale, emerging studies have dealt with scalable approaches to show commercial feasibility. This review summarizes the recent studies on diverse graphene membrane fabrications and their environmental applications related to water-containing conditions in addition to the molecular separation mechanism and critical factors related to graphene membrane performance. Additionally, we discuss future perspectives and challenges to provide insights into the practical applications of graphene-based membranes on the industrial scale.
Layered two-dimensional materials can potentially be utilized for organic solvent nanofiltration (OSN) membrane fabrication owing to their precise molecular sieving by the interlayer structure and excellent stability in harsh conditions. Nevertheless, the extensive tortuosity of nanochannels and bulky solvent molecules impede rapid permeability. Herein, nanoporous graphene (NG) with a high density of sp2 carbon domain was synthesized via sequential thermal pore activation of graphene oxide (GO) and microwave-assisted reduction. Due to the smooth sp2 carbon domain surfaces and dense nanopores, the microwave-treated nanoporous graphene membrane exhibited ultrafast organic solvent permeance (e.g., IPA: 2278 LMH/bar) with excellent stability under practical cross-flow conditions. Furthermore, the membrane molecular weight cut-off (MWCO) is switchable from 500 Da size of molecule to sub-nanometer-size molecules depending on the solvent type, and this switching occurs spontaneously with solvent change. These properties indicate feasibility of multiple (both binary and ternary) organic mixture separation using a single membrane. The nanochannel structure effect on solvent transport is also investigated using computation calculations.
Two-dimensional materials have garnered significant attention as membrane building blocks for their tunability, which enables simultaneous enhancement of permeance and selectivity. This study investigates the impact of reduced nanosheet width on H2/CO2 separation by examining the gas permeation behavior of graphene oxide nanoribbon (GONR)/polymer hybrid membranes. Polymers are incorporated into the macroporous GONR scaffold to accelerate H2 transport due to the expansion of GONR nanochannels. The GONR/polymer scaffolds can be coated on porous support by using the scalable shear coating method, resulting in micrometer-scale selective layers. The carbon layers remain intact after polymer hybridization and inhibit polymer crystallization, allowing strong polymer-CO2 interactions to hinder CO2 permeation. However, the excessive polymer composition can compromise GONR-polymer hybridization and crystallization suppression. We also explore the effect of polymer charge on gas separation performance. A relatively small amount of cationic polymer enhances H2/CO2 selectivity, but the enhancement is limited due to strong electrostatic interactions. Anionic polymer-GONR hybridization also improves gas separation performance, but is less effective compared to neutral polymer, as repulsive interactions result in a looser structure. The gas separation performance of the optimized membrane (GONR/PEO 25 wt%) shows H2 permeability of 7,108 Barrer and H2/CO2 selectivity of 10.8, surpassing the Robeson upper bound for polymeric membranes and comparable to that of previous 2D-materials-based membranes. Our finding demonstrates that GONR nanochannels and their gas transport properties can be tuned by simply adding polymers depending on the quantity, molecular weight, and charge of the polymers.
AbstractOne of the main motivations of this research is to develop an adaptable Virtual Reality (VR) model whose color can be changed dynamically according to the identified emotional state of a user. This paper addresses how to capture a specific user′s emotion through the web and use it for modifying VR model mainly for color adaptation. This adaptation process of a VR model consists of three phases: 1) identification of the user′s emotional state projected onto the selected paintings, 2) translation of those captured emotional keywords into a pertinent set of color coordinations, and finally, 3) automated color adaptation process for the given VR model. In this paper, we introduced a method of using well-known paintings and their variations to derive an on-line viewer′s emotional state which can be utilized to find a new color scheme reflecting the identified emotion. This color harmony scheme can provide a useful information for a dynamic color coordination for the objects embedded in the given VR model. The outcome of this study could enable an interactive and dynamic VR model supporting emotion-responsive interior design simulations or the visionary scenario of the architectural environment where interior colors are changed according to the captured mood of the occupant.Keywordsemotion-responsivecolor, VR model
Graphene oxide nanoribbons (GONR) are prepared by the top-down oxidative unzipping of carbon nanotubes. The unique one-dimensional morphology and the abundant functional groups of GONR distinguish it from other graphene-based carbon materials with increased solvent dispersibility and self-assembly behavior. These features have been exploited throughout the literature for various applications, including energy storage materials, sensors, catalysts, fillers for composites, and separation membranes. However, despite its drastically different chemical and physical properties, GONRs are often only discussed in the sub-context of graphene nanoribbons. This Perspective highlights GONRs specifically, focusing on their chemical properties and structuring behaviors, which can be manipulated to yield appealing structures for target applications. These characteristics constitute significant importance in scalable applications. The final section of this Perspective catalogs a comprehensive summary of recent GONR developments and additional perspectives for future research.
Developing bioelectronics that retains their long-term functionalities in the human body during daily activities is a current critical issue. To accomplish this, robust tissue adaptability and biointerfacing of bioelectronics should be achieved. Hydrogels have emerged as promising materials for bioelectronics that can softly adapt to and interface with tissues. However, hydrogels lack toughness, requisite electrical properties, and fabrication methodologies. Additionally, the water-swellable property of hydrogels weakens their mechanical properties. In this work, an intrinsically nonswellable multifunctional hydrogel exhibiting tissue-like moduli ranging from 10 to 100 kPa, toughness (400-873 J m
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