High-value utilization of mask and heavy fraction of bio-oil: From hazardous waste to biochar, bio-oil, and graphene films

At present, it is very common to wear mask outdoors in order to avoid coronavirus disease 19 (COVID-19) infection. However, this leads to the formation of numerous plastic wastes that threaten humans and ecosystem. Against this major background, a novel co-pyrolysis coupled chemical vapor deposition (CVD) strategy is proposed to systematically convert mask and heavy fraction of bio-oil (HB) into biochar, bio-oil, and three-dimensional graphene films (3DGFs) is proposed. The biochar exhibits high higher heating value (HHV) (33.22-33.75 MJ/kg) and low ash content (2.34%), which is obviously superior to that of the walnut shell and anthracite coal. The bio-oil contains rich aromatic components, such as 1,2-dimethylbenzene and 2-methylnaphthalene, which can be used as chemical feedstock for insecticides. Furthermore, the 3DGF₈₀₀ has a wide range of applications in the fields of oil spill cleanup and oil/water separation according to its fire resistance, high absorbability (40-89 g g^-1) and long-term cycling stability. This research sheds new light on converting plastic wastes and industrial by-products into high added-value chemicals.

Selective 5-Hydroxymethylfurfural Hydrogenolysis to 2,5-Dimethylfuran over Bimetallic Pt-FeOx/AC Catalysts

The selective hydrogenolysis of 5-hydroxymethylfurfural (HMF) platform molecule to 2,5-dimethylfuran (DMF) has attracted increasing attention due to its broad range of applications. However, HMF, with multiple functional groups, produces various byproducts, hindering its use on an industrial scale. Herein, a bimetallic Pt-FeOx/AC catalyst with low Pt and FeOx loadings for selective HMF hydrogenolysis to DMF was prepared by incipient wetness impregnation. The structures and properties of different catalysts were characterized by XRD, XPS, TEM, ICP-OES and Py-FTIR techniques. The addition of FeOx enhanced Pt dispersion and the Lewis acidic site density of the catalysts, and was found to be able to inhibit C=C hydrogenation, thereby im-proving DMF yield. Moreover, the presence of Pt promoted the reduction of iron oxide, creating a strong interaction between Pt and FeOx. This synergistic effect originated from the activation of the C–O bond over FeOx species followed by hydrogenolysis over the adjacent Pt, and played a critical role in hydrogenolysis of HMF to DMF, achieving a yield of 91% under optimal reaction conditions. However, the leaching of Fe species caused a metal–acid imbalance, which led to an increase in ring hydrogenation products.

Gold nanoparticles modified graphene foam with superhydrophobicity and superoleophilicity for oil-water separation

Leakage accidents often occur during the production, transportation, and use of petroleum products, which is a common and serious environmental issue. It is of great significance and challenge to develop efficient materials for oil-water separation. This article introduces a simple and feasible method to prepare high-performance 3D graphene foam (GF) oil-absorbing material. Gold nanoparticles (Au NPs) are loaded on the surface of graphene foam by ion sputtering and then modified with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT). The prepared graphene sponge is porous with a large specific surface area and excellent water repellency (water contact angle exceeding 150°). The superhydrophobicity of the materials is due to the interaction between the rough structure of gold nanoparticles and the reduction of surface energy by PFDT. These outstanding properties make the functionalized graphene foam have excellent oil absorption capacity, which can even be as high as 25.8 g/g, and it can still maintain high separation performance after 10 cycles of recycling. It is worth noting that the preparation of the material is simple and reusable. Therefore, the prepared graphene foam has the potential as a promising absorbent for oil spill purification.

Applications of Graphene and Its Derivatives in the Upstream Oil and Gas Industry: A Systematic Review

Graphene and its derivatives, with their unique two-dimensional structures and excellent physical and chemical properties, have been an international research hotspot both in the research community and industry. However, in application-oriented research in the oil and gas industry they have only drawn attention in the past several years. Their excellent optical, electrical, thermal and mechanical performance make them great candidates for use in oil and gas exploration, drilling, production, and transportation. Combined with the actual requirements for well working fluids, chemical enhanced oil recovery, heavy oil recovery, profile control and water shutoff, tracers, oily wastewater treatment, pipeline corrosion prevention treatment, and tools and apparatus, etc., this paper introduces the behavior in water and toxicity to organisms of graphene and its derivatives in detail, and comprehensively reviews the research progress of graphene materials in the upstream oil and gas industry. Based on this, suggestions were put forward for the future research. This work is useful to the in-depth mechanism research and application scope broadening research in the upstream oil and gas industry.

Fabrication of regular macro-mesoporous reduced graphene aerogel beads with ultra-high mechanical property for efficient bilirubin adsorption

Three-dimensional graphene materials have been widely studied in many fields for their role as potential absorbent, especially for bilirubin adsorption. In this study, we developed a simple method to prepare reduced graphene aerogel beads as hemoperfusion materials for fast bilirubin adsorption. The graphene oxide (GO) aerogel beads were produced by self-assembly of GO nanosheet that cross-linked by Ca²⁺ previously in a coagulation bath, then it was reduced by ascorbic acid and lyophilized to yield the reduced graphene aerogel beads. The beads had a regular macroscopic spherical structure with a diameter of about 1.3-2 mm, where the macroporosity was about 10 μm and the mesoporosity was about 12 nm. The macro-mesoporous structure also gave the reduced graphene aerogel beads ultra-high mechanical strengths and high specific surface area, which were both important for hemoperfusion materials. Moreover, the fixed-bed column adsorption revealed that the reduced graphene aerogel beads manifested excellent bilirubin adsorption (649.512 mg/g) with a rapid adsorption equilibrium time (1.5 h) under the optimized conditions. Even in the bilirubin-enriched blood, the adsorption capacity of the beads could reach 367.14 mg/g. Furthermore, the aerogel beads had a low hemolysis ratio and improved anticoagulant property showing good blood compatibility. Hence, the spherical reduced graphene aerogel beads with millimeter-level size presented a good potential for clinical applications in hemoperfusion therapy.

Superhydrophobic and superoleophilic graphene aerogel for adsorption of oil pollutants from water

Three-dimensional graphene based materials with superhydrophobic/superoleophilic attributes are highly desirable for water treatment. The graphene aerogel (GA) was prepared by hydrothermal reaction of the graphene oxide (GO) solution in the presence of dopamine followed by freeze-drying. The subsequent surface modification of GA using fluoroalkylsilane occurred by a vapor-liquid deposition process. The superhydrophobic graphene aerogel (SGA) fabricated from GA exhibits superhydrophobicity and superoleophilicity with the water contact angle of 156.5° and the oil contact angle of 0°. With this property, SGA could selectively adsorb various types of oils/organic solvents from the oil-water mixture. Moreover, the SGA possesses excellent low bulk density (9.6 mg cm-3), high absorption capacity (110-230 fold weight gain), and superior adsorption recyclability. With all these desirable features, the SGA is a promising candidate for oil-polluted water remediation.

Environmental performance of graphene-based 3D macrostructures

Three-dimensional macrostructures (3DMs) of graphene and graphene oxide are being developed for fast and efficient removal of contaminants from water and air. The large specific surface area, versatile surface chemistry and exceptional mechanical properties of graphene-based nanosheets enable the formation of robust and high-performance 3DMs such as sponges, membranes, beads and fibres. However, little is known about the relationship between the materials properties of graphene-based 3DMs and their environmental performance. In this Review, we summarize the self-assembly and environmental applications of graphene-based 3DMs in removing contaminants from water and air. We also develop the critical link between the materials properties of 3DMs and their environmental performance, and identify the key parameters that influence their capacities for contaminant removal.

Energy-Efficient Oil-Water Separation of Biomimetic Copper Membrane with Multiscale Hierarchical Dendritic Structures

Membrane-based materials with special surface wettability have been applied widely for the treatment of increasing industrial oily waste water, as well as frequent oil spill accidents. However, traditional technologies are energy-intensive and limited, either by fouling or by the inability of a single membrane to separate all types of oil-water mixtures. Herein, a biomimetic monolayer copper membrane (BMCM), composed of multiscale hierarchical dendritic structures, is cleverly designed and successfully fabricated on steel mesh substrate. It not only possesses the ability of energy-efficient oil-water separation but also excellent self-recovery anti-oil-fouling properties (<150 s). The BMCM even keeps high separation efficiency (>93%) after ten-time cycling tests. More importantly, it retains efficient oil-water separation capacity for five different oils. In fact, these advanced features are benefited by the synergistic effect of chemical compositions and physical structures, which is inspired by the typical nonwetting strategy of butterfly wing scales. The findings in this work may inspire a facile but effective strategy for repeatable and antipollution oil-water separation, which is more suitable for various applications under practical conditions, such as wastewater treatment, fuel purification, separation of commercially relevant oily water, and so forth.

One-step modification of PU sponges for selective absorption of oil–water mixtures

Superhydrophobic PDMS–PU sponges fabricated through dipping–coating and HCl corrosion method exhibit excellent oil–water separation property.

Green-assembly of three-dimensional porous graphene hydrogels for efficient removal of organic dyes

Herein, a facile and straightforward green-assembly approach was developed for preparation of nitrogen and sulphur co-doped three-dimensional (3D) graphene hydrogels (N/S-GHs) with the assistance of glutathione. Specifically, graphene oxide is reduced and assembled into 3D porous nanostructures with glutathione as the reducing agent and modifier for its intrinsic structure, along with the nitrogen and sulphur sources in the synthetic process. As expected, the as-obtained N/S-GHs demonstrated superior adsorption performances for organic dyes (e.g., methylene blue, malachite green, and crystal violet) in aqueous media. This work provides new insight for the green-assembly of 3D porous nanomaterials as adsorbent and their promising applications in water treatment.