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Large volumes of slags are formed as by-products during the refinement of pig iron by basic oxygen steelmaking or electric arc furnace steelmaking. In order to lower the environmental ...impact of the steel industry and ensure its economic sustainability, there have been significant studies finding the ways to recycle by-products. The formation, composition and physical properties of steel making slag are discussed with regard to the problems associated with its reuse. The volume instability caused by free lime exposure to moisture means that the reuse of steelmaking slag is often limited as many potential applications, and the leaching behavior of steelmaking slag is important for environmental considerations. Land-based applications that have been demonstrated include replacing natural sand as aggregate in cement, which may be combined with the CO2 sequestration properties. Steel slag shows use as a liming material (when spread over acidic soils to help to raise the pH to a more neutral level) and to enhance the physical properties of soft soils. Potential benefits to the marine environment is due to high porosity and large surface area, making slags ideal for coral reef repair (e.g., overcoming coral bleaching) and replacement (e.g., artificial reef to promote growth of green marine plants and seagrass), as well as a growth promoter for seaweed and phytoplankton that are microscopic organisms that are an essential component of ecosystems in oceans around the world. The chemistry of steelmaking slag also makes it a contender for adsorption of H2S and metalloids from marine environments.
Post‐synthetic ligand exchange in the prototypical zirconium‐based metal–organic framework (MOF) UiO‐66 was investigated by in situ solution 1H NMR spectroscopy. Samples of UiO‐66 having different ...degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect‐free UiO‐66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing‐cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical‐chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework.
Defects matter: a combination of in situ NMR spectroscopy and ex situ characterisation confirms that post‐synthetic ligand exchange on defective UiO‐66 occurs preferentially at missing‐cluster defective sites.
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The wetting characteristics of coatings created using functionalised nanoparticles and adhesive resins, depends strongly on the particle distribution within the surface layers. ...Although it has been shown that commercially available adhesives improve the durability of hydrophobic nanoparticle coatings, the wettability of these surfaces is governed by the agglomeration behaviour of the particles within the adhesive. As a consequence of this, coatings where the particles are highly agglomerated within the adhesive show lower hydrophobicity.
The morphology and chemical composition of coatings formed from carboxylate functionalised Al2O3 and magnetite (Fe3O4) nanoparticles and epoxy resin on plastic was studied using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Water contact angle (WCA) measurements were used to investigate how the coatings’ morphological characteristics and loading of the particles within the surface layers influenced their wettability. Infrared (IR) spectroscopy and thermogravimetric analysis (TGA) were used to study carboxylate adsorption onto the magnetite nanoparticles.
Combining the Al2O3 nanoparticles with epoxy resin was observed to create highly hydrophobic coatings that displayed water contact angles (WCAs) between 145 and 150°. These coatings displayed good durability when sonicated in isopropanol and wiped with tissue. By comparison, coatings formed from the magnetite nanoparticles were substantially less hydrophobic and displayed WCAs between 75 and 125° when combined with epoxy resin. SEM revealed that the magnetite nanoparticles in the coatings were present as large agglomerates. By comparison, coatings formed from the Al2O3 nanoparticles showed a more homogenous particle distribution. Furthermore, XPS showed that the resin engulfed the magnetite nanoparticles to a far greater extent. The difference in wetting behaviour of these coatings is largely attributed to their different morphologies, since the particles are similar sizes and TGA shows that the particles possess similar carboxylate grafting densities. The uneven distribution of nanoparticles in the magnetite/epoxy resin coating is due to the particles’ magnetic properties, which drive nanoparticle agglomeration as the coatings solidify. This work demonstrates that it is important to consider inter-particle interactions when fabricating low wettability composite coatings.
We present a new class of superhydrophobic surfaces created from low-cost and easily synthesized aluminum oxide nanoparticles functionalized carboxylic acids having highly branched hydrocarbon (HC) ...chains. These branched chains are new low surface energy materials (LSEMs) which can replace environmentally hazardous and expensive fluorocarbons (FCs). Regardless of coating method and curing temperature, the resulting textured surfaces develop water contact angles (θ) of ∼155° and root-mean-square roughnesses (R q) ≈ 85 nm, being comparable with equivalent FC functionalized surfaces (θ = 157° and R q = 100 nm). The functionalized nanoparticles may be coated onto a variety of substrates to generate different superhydrophobic materials.
We report a simple, high-yield, method of producing homogeneous dispersions of unfunctionalized and nonoxidized graphene nanosheets in ortho-dichlorobenzene (ODCB). Sonication/centrifugation of ...various graphite materials results in stable homogeneous dispersions. ODCB dispersions of graphene avert the need for harsh oxidation chemistry and allow for chemical functionalization of graphene materials by a range of methods. Additionally, films produced from ODCB-graphene have high conductivity.
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Nanoparticle embedding into the surface of plastics provides an effective anchor that improves the durability of coatings formed from functionalized nanoparticles. Coatings formed ...from thermally embedded particles show superior wear resistance relative to coatings formed from non-embedded particles. As a consequence of this, embedded nanoparticles functionalized with hydrophilic and hydrophobic carboxylates are better suited for controlling the wettability of plastics than when the nanoparticles are deposited onto the plastic under ambient conditions.
Carboxylate-functionalized Al2O3 nanoparticles were embedded into ethylene vinyl acetate through spray coating the particles onto the substrate during heating. Sonication was used to remove excess particles that did not become embedded into the material. Coatings formed from the embedded particles were characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The wettability of the coatings was characterized using static and dynamic contact angle (CA) measurements to measure the apparent water contact angles, and sliding angle measurements, whilst the durability of the coatings was studied using scratch testing, tape peel tests, and abrasion tests. The build-up of fog on the substrates was also studied through exposing the surfaces to water vapour.
Thermal embedding of the particles into the surface of the plastic was observed to occur when the material was heated to temperatures around its melting temperature. AFM and SEM showed that plastic embedded with the nanoparticles possessed a morphology that was substantially rougher than the untreated plastic. CA measurements showed that plastic embedded with hydrophobic isostearate functionalized nanoparticles was highly hydrophobic and displayed a CA of approximately 152°. Dynamic CA measurements and sliding angle measurements revealed that plastic embedded with the isostearate functionalized nanoparticles showed petal-like wetting behavior. Furthermore, it was observed that the CA of the plastic could be varied from highly hydrophobic to highly hydrophilic through embedding varying amounts of isostearate and hydrophilic 2-2-(2-methoxyethoxy)ethoxyacetate functionalized Al2O3 nanoparticles into the surface of the material. Scratch testing showed that thermally embedding the nanoparticles into the plastic substantially improved their abrasion resistance, relative to when the nanoparticles are deposited onto the non-heated material. This methodology indicates that embedding nanoparticles into plastics creates durable coatings that can display variable wettability. Consequently, this methodology could be useful in applications where it is desirable to keep plastics dry, such as for food packaging or medical devices.
The synergistic effects of fumed-Si nanoparticles (Si-NPs) in combination with sodium dodecyl sulfate (SDS) surfactant as suitable agents for oil displacing in enhanced oil recovery (EOR) are ...evaluated using a 5-spot glass micromodel. Optimum oil recovery (45%) is obtained for SDS near the critical micelle concentration; however, the addition of fumed silica nanoparticles (Si-NPs) enables a further 13% enhancement in oil recovery for the maximum concentration of the SDS/Si-NPs (2.2 wt %) as well as delaying the breakthrough point. The optimum mass ratio of SDS:Si-NP (1:11) suggests that the Si-NPs are aggregated by the SDS micelles, consistent with increased viscosity upon addition of Si-NPs. The presence of the Si-NPs also greatly increases the wettability on the glass surface with a decrease in the contact angle from 73° for SDS (1800 ppm) to 11° for SDS/Si-NPs (1800 ppm/2.0 wt %). The effective changes in the oil sweeping mechanism are directly observed in the glass micromodel and correlate to these physical measurements. The results demonstrated that addition of Si-NPs to SDS solutions made a significant improvement to oil recovery values and is potentially beneficial in EOR applications.
For the additive white Gaussian noise channel with average codeword power constraint, coding methods are analyzed in which the codewords are sparse superpositions, that is, linear combinations of ...subsets of vectors from a given design, with the possible messages indexed by the choice of subset. Decoding is by least squares (maximum likelihood), tailored to the assumed form of codewords being linear combinations of elements of the design. Communication is shown to be reliable with error probability exponentially small for all rates up to the Shannon capacity.
Decoupling amine loading from diffusion resistance is one of the main challenges in the development of immobilized amine CO2 sorbents. Water has been reported to serve this goal, alleviating CO2 ...diffusional hindrance in highly loaded amine sorbents. Acting as a mass transport facilitator, water is not the only partner molecule able to enhance bulk CO2 diffusion. Herein, we show that the enhancing effect of methanol is comparable to that of water in polyethylenimine-based sorbents. Other molecules, such as ethanol, isopropanol, and chloroform, were also examined but did not appear to facilitate CO2 transport and uptake. Based on a comparison of the Hansen solubility parameters of these molecules, it appears that polarity plays a crucial role in enhancing CO2 diffusion together with molecular hindrance and hydrogen bonding to a lesser extent.
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