Advanced materials for the efficient treatment of textile wastewater need to be developed for the sustainable growth of the textile industry. In this study, graphene oxide (GO) was modified by the ...incorporation of natural clay (bentonite) and mixed metal oxide (copper-cobalt oxide) to produce GO-based binary and ternary composites. Two binary composites, GO/bentonite and GO/Cu–Co Ox (oxide), and one ternary composite, GO/bentonite/Cu–Co Ox, were characterized by Fourier transform-infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Brunauer-Emmett-Teller (BET) analysis. The adsorption efficiency of these composites was evaluated against a cationic dye, Basic Blue 41 (BB41). The composites had several surface functional groups, and the ternary composite had tubular porous structures formed by the cross-linking of the bentonite and GO planes. The BET surface area of the ternary composite was 50% higher than that of the GO. The BB41 removals were 92, 89, 80, and 69% for GO/bentonite/Cu–Co oxide, GO/bentonite, GO and GO/Cu–Co oxide, respectively. The pseudo-2nd-order and intraparticle diffusion models best describe the kinetics results, indicating chemisorption and slow pore diffusion-controlled adsorption processes. The Langmuir isotherm-derived adsorption capacity of GO/bentonite/Cu–Co oxide was 351.1 mg/g, which was very close to the measured value. After five consecutive cycles, the ternary composite retained 90% BB41 removal efficiency compared to its 1st cycle. Electrostatic interaction and pore diffusion were predicted to be the controlling mechanisms for the adsorption of the BB41. The GO-based ternary composite can be a feasible and scalable adsorbent for BB41 in wastewater treatment.
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•Graphene oxide (GO) was intercalated into bentonite layers, with crumpled and tubular pore structures.•Carboxylic, hydroxyl, epoxide, and carbonyl groups were present on GO/bentonite/Cu–Co oxide (Ox).•GO/bentonite/Cu–Co Ox has 40 and 50% greater surface area and adsorption capacity than GO.•GO/bentonite/Cu–Co Ox retained ∼90% efficiency after 5 consecutive cycles compared to the 1st cycle.•Kinetics studies: chemical interaction dominated the adsorption process for basic blue 41 (BB41).
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•It is a bio-based carbon aerogel that is environmentally friendly.•The morphology could be controlled by using different freezing methods.•It could absorb oils and organic solvents ...up to 288 times of its own weight.•The carbon aerogels exhibited outstanding compressibility and recyclability.
In increasingly serious marine pollution environment, environmentally friendly low-density aerogels have become potential oil-water separation materials. However, many reported aerogels have the drawbacks of low oil absorption, poor compressibility and flexibility, which limit their application. Herein, we reported a compressible, anisotropic lamellar hydrophobic and lipophilic graphene/polyvinyl alcohol/cellulose nanofiber carbon aerogel (a-GPCCA) prepared by directional freeze-drying and carbonization processes. The synthetic ultralight a-GPCCA had low density (6.17 mg/cm3) and high porosity (99.61 %). Moreover, directional freeze-drying resulted in a lamellar interpenetrated three-dimensional porous structure, which endowed it with high adsorption capacity (155–288 times of its weight), good compressibility (95 % recovery after repeating 15 cycles at 50 % strain in parallel to the freezing direction) and recyclability (oil retention rate reached 88.8 % after 10 absorption-compression cycles). Furthermore, carbonization provided it with excellent thermal stability and hydrophobic properties, resulting in oil-water selectivity and combustion cyclicity (the oil absorption capacity was reduced by only 10.2 % after 10 absorption-combustion cycles). Therefore, the a-GPCCA obtained in this study possesses a promising potential in the field of treatment of offshore oil spills and domestic industrial wastewater.
Zeolites with ordered microporous systems, distinct framework topologies, good spatial nanoconfinement effects, and superior (hydro)thermal stability are an ideal scaffold for planting diverse ...active metal species, including single sites, clusters, and nanoparticles in the framework and framework-associated sites and extra-framework positions, thus affording the metal-in-zeolite catalysts outstanding activity, unique shape selectivity, and enhanced stability and recyclability in the processes of Brønsted acid-, Lewis acid-, and extra-framework metal-catalyzed reactions. Especially, thanks to the advances in zeolite synthesis and characterization techniques in recent years, zeolite-confined extra-framework metal catalysts (denoted as metal@zeolite composites) have experienced rapid development in heterogeneous catalysis, owing to the combination of the merits of both active metal sites and zeolite intrinsic properties. In this review, we will present the recent developments of synthesis strategies for incorporating and tailoring of active metal sites in zeolites and advanced characterization techniques for identification of the location, distribution, and coordination environment of metal species in zeolites. Furthermore, the catalytic applications of metal-in-zeolite catalysts are demonstrated, with an emphasis on the metal@zeolite composites in hydrogenation, dehydrogenation, and oxidation reactions. Finally, we point out the current challenges and future perspectives on precise synthesis, atomic level identification, and practical application of the metal-in-zeolite catalyst system.
Supramolecular plastics (SMPs) can be made mechanically robust, repairable, and recyclable, rendering themselves promising alternatives to their conventional predecessors to address environmental ...concerns. However, dense accumulations of noncovalent bonds generally lead to mechanical brittleness as well as intolerance toward heat and moisture. To resolve this issue, a simple strategy of preparing high‐performance SMP by constructing highly dense, but irregular hydrogen‐bond networks with hierarchical structures is proposed. The resultant SMP exhibits an outstanding combination of good comprehensive mechanical properties (high stiffness, strength, and toughness with ductile failure when fracturing), excellent dynamic behaviors (repairability and recyclability), and high tolerances toward moisture and high temperatures (as high as 90 °C). Additionally, the SMP also shows a high dielectric constant, exhibiting great potential for applications such as healable flexible touch screens and energy storage. Last, through structure characterizations and molecular dynamic simulation, this study provides a fundamental insight into the mechanism behind such high‐performances from nano‐ to micro‐scales, which is expected to inspire the design of a wide range of other SMPs that use different chemistries.
An ingenious construction of highly‐stacked, irregularly arranged, and hierarchical hydrogen‐bonding networks are designed to prepare a novel supramolecular plastic, which is colorless, transparent, robust, tough, humidity‐and heat‐resistant, and showed excellent repairability, recyclability, and high dielectric constant. The integration of these properties enables its potential applications in flexible touch screens and energy storage.
The development of new chemically recyclable polymers via monomer design would provide a transformative strategy to address the energy crisis and plastic pollution problem. Biaryl‐fused cyclic esters ...were targeted to generate axially chiral polymers, which would impart new material performance. To overcome the non‐polymerizability of the biaryl‐fused monomer DBO, a cyclic ester Me‐DBO installed with dimethyl substitution was prepared to enable its polymerizability via enhancing torsional strain. Impressively, Me‐DBO readily went through well‐controlled ring‐opening polymerization, producing polymer P(Me‐DBO) with high glass transition temperature (Tg >100 °C). Intriguingly, mixing these complementary enantiopure polymers containing axial chirality promoted a transformation from amorphous to crystalline material, affording a semicrystalline stereocomplex with a melting transition temperature more than 300 °C. P(Me‐DBO) were capable of depolymerizing back to Me‐DBO in high efficiency, highlighting an excellent recyclability.
To overcome the non‐polymerizability of the biaryl‐fused monomer DBO, a cyclic ester Me‐DBO installed with dimethyl substitution was prepared to enable its polymerizability via enhancing torsional strain while preserving an excellent recyclability. Remarkably, mixing these complementary enantiopure polymers containing axial chirality promoted a transformation from amorphous to crystalline material.
Channeling carbon dioxide
The separation of gas molecules with physisorbents can be challenging because there is often a tradeoff between capacity and selectivity. Zhou
et al.
report a template-free ...hydrothermal synthesis of the one-dimensional channel zeolite mordenite, in which some silicon was replaced by iron. Rather than forming a powder that requires further shaping, this mechanically stable material self-assembled into monoliths. Iron atoms bound in tetrahedral zeolite sites narrowed the channels and enabled the size-exclusion separation of carbon dioxide (CO
2
) over nitrogen (N
2
) and methane. High CO
2
uptake and highly efficient CO
2
–N
2
separation was demonstrated for both dry and humid conditions.
Science
, aax5776, this issue p.
315
Self-molded iron mordenite monoliths have high physisorbed CO
2
uptakes that enable separation from N
2
and CH
4
.
The development of low-cost, efficient physisorbents is essential for gas adsorption and separation; however, the intrinsic tradeoff between capacity and selectivity, as well as the unavoidable shaping procedures of conventional powder sorbents, greatly limits their practical separation efficiency. Herein, an exceedingly stable iron-containing mordenite zeolite monolith with a pore system of precisely narrowed microchannels was self-assembled using a one-pot template- and binder-free process. Iron-containing mordenite monoliths that could be used directly for industrial application afforded record-high volumetric carbon dioxide uptakes (293 and 219 cubic centimeters of carbon dioxide per cubic centimeter of material at 273 and 298 K, respectively, at 1 bar pressure); excellent size-exclusive molecular sieving of carbon dioxide over argon, nitrogen, and methane; stable recyclability; and good moisture resistance capability. Column breakthrough experiments and process simulation further visualized the high separation efficiency.
The ever-increasing oil spill accidents from industries and the daily life have caused serious economic loss, destroyed the ecological environment and threatened human health. In order to solve this ...problem, designing and fabricating efficient separation membrane materials is an efficient way for oil/water emulsion separation and thus has aroused tremendous attention. We present a comprehensive overview on the separation membrane materials with controlled pore structure, tunable wettability for highly efficient oil/water emulsion separation. Separation mechanism was introduced at first, followed by introduction of the most frequently studied membrane materials. Based on the membrane substrate, general oil/water emulsion separation membrane can be categorized into polymer membrane, inorganic membrane, metal mesh membrane, gel membrane and biomass membrane. Besides, faced with the common problem of membrane pollution and damage, special functional membranes such as self-cleaning membrane, self-healing membrane, Janus membrane, and smart responsive membrane have aroused wide attention in recent years. For each membrane material, representative studies have been summarized, focusing on the synergy influence of the porous structure and selective wettability on the oil/water emulsion separation performance. Finally, the challenges, current trends and future perspectives of the oil/water emulsion separation membrane materials have also been proposed.
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•This article reviews the latest research work published in the past five years.•The perspective of raw materials, fabrication methods, and application performance have been summarized.•Development trend and challenge of each material are also concluded in the review.
The use of waste plastic into asphalt concrete paving mix (ACP) has been explored in recent literature to improve the functional properties of the mix. However, exploration on their recyclability ...potential at the end of its service life remains scarce. This study explores the potential of recycling aged waste plastic-modified asphalt concrete (AACP) for road pavements, with focus on four commonly disposed household plastics: high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) and polyethylene (PET). Marshall stability test, Cantabro abrasion test, indirect tensile strength test, resilient modulus (MR) test, Hamburg’s wheel tracking test and stripping test were performed to evaluate the engineering properties of recycled waste plastic-modified asphalt concrete (RACP) containing proportions ranging from 20 % to 100 % aged component (AACP) blended with virgin mixtures. This paper highlights significant engineering performance of RACP, and most notably for RACP containing PP with 20 % aged content which exhibits 1.6 times greater resistance to moisture damage compared to conventional recycled asphalt concrete (RAPA). Although RACP with HDPE and PP (consisting of 20 % and 40 % AACP in mix) yield improvements in resilient modulus over RAPA, this improvement is less pronounced for RACP with PS and PET. Overall, RACP with 40 % aged components exhibits better rutting, moisture damage and abrasion loss performance, along with improved stability and flow value. Environmental impact in terms of water leachability was also found to be negligible in this study and RACP can be considered a feasible sustainable pavement material, with potential for second and more lives.
•The recyclability potential of plastic-modified asphalt concrete was investigated.•Recycling mix containing 20 % to 100 % aged content enhance overall performance.•Polypropylene-modified recycling mix outperforms other plastic-modified mixes.•Water contaminants leaching is minimal on plastic-modified recycled asphalt mixes.•Waste Plastic-modified asphalt is recyclable for full circular economy.
Naturally-derived biopolymers such as alginate, chitosan, cellulose, agarose, guar gum/guaran, agar, carrageenan, gelatin, dextran, xanthan, and pectins, etc. have appealed significant attention over ...the past several years owing to their natural abundance and availability all over the years, around the globe. In addition, their versatile properties such as non-toxicity, biocompatibility, biodegradability, flexibility, renewability, and the availability of numerous reactive sites offer significant functionalities with multipurpose applications. At present, intensive research efforts have been focused on engineering enzymes using natural biopolymers as novel support/composite materials for diverse applications in biomedical, environmental, pharmaceutical, food and biofuel/energy sectors. Immobilization appears as a straightforward and promising approach to developing biocatalysts with improved catalytic properties as compared to their free counterparts. Biopolymers-assisted enzymes are more stable, robust, and recoverable than that of free forms, and can be employed for continuous biocatalytic reactions. The present review highlights the recent developments and use of biopolymers and their advanced composites as support carriers for the immobilization of a variety of different enzymes to develop biocatalysts with desired catalytic activity and stability characteristics for emerging applications.
•Herein, naturally-derived biopolymers as potential platforms for enzyme immobilization are reviewed.•Physiochemical and immobilization aspects are discussed.•Intensive research efforts are being focused on engineering enzymes using natural biopolymers.•Immobilized enzymes are stable, robust, and recoverable than that of free forms.
Due to their dynamic, stimuli-responsive nature, non-covalent interactions represent versatile design elements that can be found in nature in many molecular processes or materials, where adaptive ...behavior or reversible connectivity is required. Examples include molecular recognition processes, which trigger biological responses or cell-adhesion to surfaces, and a broad range of animal secreted adhesives with environment-dependent properties. Such advanced functionalities have inspired researchers to employ similar design approaches for the development of synthetic polymers with stimuli-responsive properties. The utilization of non-covalent interactions for the design of adhesives with advanced functionalities such as stimuli responsiveness, bonding and debonding on demand capability, surface selectivity or recyclability is a rapidly emerging subset of this field, which is summarized in this review.
This review highlights bio-inspired design approaches that utilize supramolecular polymers to create adhesives with advanced functionality.
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