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Sugars and sugar-rich agricultural by-products are cheaper and eco-friendly alternatives to conventional reductants used in recovering metals from spent lithium-ion batteries. Still, they are rarely used due to a poor understanding of their performance and reaction chemistry. In this study, two hypotheses bearing on the role of chemistry and influence of non-sugary organic compounds (impurities) on the performance of sugars, namely: glucose, fructose and sucrose, and a parent sugar-rich agro-industrial by-product – molasses, as reductants in the leaching of Li, Co, Mn and Ni from spent lithium-ion battery cathode material were tested. Statistical analysis using ANOVA revealed that the performance of the sugars and molasses are similar with >85% Mn, >88% Ni, >88%Co and >98% Li leached at 90 °C and 60 min. This shows that the presence of non-sugar organic compounds does not hamper the performance of the sugars-based reductants. The performance of the sugars relies more on temperature than chemistry. Furthermore, evaluation of the oxidation pathway hints at a potential inhibition of secondary oxidation reactions at lower temperatures. This study provides statistically validated proof that the performance of sugarcane molasses, even at lower concentration, is equipollent to the pure sugars in the leaching of critical metals from spent lithium-ion batteries.

Rare earth elements (REEs) are a major constituent of many advanced materials in the information and telecommunication industries, as well as the renewable and energy efficiency sectors. REEs are enablers of speed, performance, durability, and low carbon emissions in these industries. They are required in everyday applications because of their unique chemical and physical properties. Given the rise in environmental concerns and consequent demand for REEs and the limited locations where REEs can be sourced, there is a very high risk of supply disruption.Despite the threat of REE supply risk and its environmental and economic significance, an in-depth examination of the environmental impact and benefits of sustainable consumption of these metals in Australia, as in many other parts of the world, holistically and systematically is lacking, particularly regarding improvement in resource efficiency strategies. Most previous work on REEs has focused either on the politico-economic conflicts over supply and distribution, or the environmental and social impacts of its production and has not holistically examined this problem, as a system.This paper provides a review of REEs' sustainable consumption in Australia. The study highlights Circular Economy (CE) as a scientifically plausible picture of sustainable management strategy to help address the adverse impacts of resource (REEs) shortages while achieving maximum environmental benefits. It provides answers to how sustainable are the current strategies of REEs consumption and how this can be enhanced from a CE perspective. A comprehensive CE framework was developed, followed by an illustrative example of CE as a tool for sustainability management and a practical implementation strategy to close the material loop and improve resource efficiency.

The effect of pyrite and the role of ammonium alcohol polyvinyl phosphate (AAPP) during gold leaching in ammoniacal thiosulfate solutions were investigated using pure gold foils. The results showed that pyrite catalyzed the decomposition and also significantly increased the consumption of thiosulfate. This detrimental effect became more severe with increasing pyrite content. Further, the presence of pyrite also substantially slowed the gold leaching kinetics and reduced the overall gold dissolution. The reduction in gold dissolution was found to be caused primarily by the surface passivation of the gold. The negative effects of pyrite, however, can be alleviated by the addition of AAPP. Comparison of zeta potentials of pyrite with and without AAPP suggests that AAPP had adsorbed on the surface of the pyrite and weakened the catalytic effect of pyrite on the thiosulfate decomposition by blocking the contact between the pyrite and thiosulfate anions. AAPP also competed with thiosulfate anions to complex with the cupric ion at the axial coordinate sites, and thus abated the oxidation of thiosulfate by cupric ions. Moreover, the indiscriminate adsorption of AAPP on the surfaces of gold and passivation species prevented the passivation of the gold surface by surface charge and electrostatic repulsion. Therefore, AAPP effectively stabilized the thiosulfate in the solution and facilitated the gold leaching in the presence of pyrite.

Magnesium-based nanocomposites were designed and developed and effect of carbon nanotubes and transition metals on hydrogen adsorption in these materials was studied. The results showed catalytic effects on the dissociative chemisorption and diffusion of hydrogen on an Mg(0001) surface when titanium and carbon are respectively incorporated into Mg materials.

Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, laboratory-on-chip devices, and near-field imaging techniques. Oil nanodroplets can be produced on a solid-liquid interface in a simple step of solvent exchange in which a good solvent of oil is displaced by a poor solvent. In this work, we experimentally and theoretically investigate the formation of nanodroplets by the solvent exchange process under well-controlled flow conditions. We find significant effects from the flow rate and the flow geometry on the droplet size. We develop a theoretical framework to account for these effects. The main idea is that the droplet nuclei are exposed to an oil oversaturation pulse during the exchange process. The analysis shows that the volume of the nanodroplets increases with the Peclet number Pe of the flow as ∝ Pe3/4, which is in good agreement with our experimental results. In addition, at fixed flow rate and thus fixed Peclet number, larger and less homogeneously distributed droplets formed at less-narrow channels, due to convection effects originating from the density difference between the two solutions of the solvent exchange. The understanding from this work provides valuable guidelines for producing surface nanodroplets with desired sizes by controlling the flow conditions. [ABSTRACT FROM AUTHOR]

Li1.0[Li1/7Mn4/7 Ni2/7]O2 cathode material was prepared by a facile, one-pot synthesis method. The structure of the material was determined by Rietveld refinement of structural models using high-resolution synchrotron X-ray and neutron powder diffraction data and was found to consist of two distinct phases. The major phase, with composition Li1.25(3)Ni0.17(1)Mn0.61(1)O2, close to the well-characterized Li1.2Ni0.2Mn0.6O2 composition can be described as an intergrowth structure of Li2MnO3 and LiMn0.5Ni0.5O2 domains and the second phase is a lithium-deficient layered structure with refined composition Li0.85(1)Ni0.57(1)Mn0.55(1)O2. The composite cathode has a high initial discharge capacity of 250 mAh/g which drops to 225 mAh/g on the 2nd discharge cycle. This capacity is maintained on subsequent cycles. Time-resolved in-situ synchrotron XRD data was used to study the changes in the lattice parameters and phase evolution of the two phases during Li-insertion and extraction. [ABSTRACT FROM AUTHOR]

Abstract  Helical mesoporous materials have attracted much attention due to their potential applications in catalysis and chiral recognition. In this paper, we have systematically studied the influence of trifluoroacetic acid, acetic acid and their salts on the synthesis of helical mesoporous materials in the presence of a cationic surfactant cetyltrimethylammonium bromide (CTAB) as a template. Results show that helical mesostructures can be successfully synthesized when CF3COO− anions were used as additives with an additive/CATB molar ratio (R) range of 0.1–0.375 for the CF3COOH/CTAB templating system and a relatively wider R range of 0.1–0.5 for the CF3COONa/CTAB templating system, which can be attributed to the influence of pH caused by the acid- or salt-form of additives. The pitch sizes of the helical mesostructures can be finely controlled by varying the additive/CTAB ratio. The results indicate that in order to synthesize helical mesostructures in a broad range of additive/CTAB ratios, the perfluorinated salt with a short fluorocarbon chain should be used. Our synthesis strategy can be used for the fabrication of helical mesostructured porous materials with adjustable pore and helical pitch sizes, which are important in their potential applications. [ABSTRACT FROM AUTHOR]

Abstract  The purpose of this study was to produce an oil-in-water nano-emulsion with different compositions of the continuous and dispersed phases through microfluidization. The aqueous phase was a solution of maltodextrin with five different emulsifying ingredients including modified starch (Capsul and Hi-Cap), sodium caseinate (SC), whey protein hydrolysate (WPH), or whey protein concentrate (WPC), while the oil phase consisted of d-limonene or fish oil. Results showed that micofluidizer was capable of producing nano-emulsions (D32 as small as 150 nm) with a narrow size distribution. Generally, moderate microfluidization pressures (42–63 MPa) and cycles (1–2) were the optimum conditions beyond which, there were adverse changes in the emulsion size. For the two oils tested as the dispersed phase, fish oil emulsions had lower Sauter mean diameters (D32) but with wider size distributions than d-limonene. When different emulsifying ingredients were compared, Hi-Cap produced nano-emulsions with the narrowest distribution but highest D32 (about 600 nm). Nano-emulsions with WPC had the smallest D32 (about 200 nm) but the widest size distribution. It was found that a d-limonene volume fraction of 0.10 was the optimum dispersed-phase concentration in terms of emulsion droplet size (D32). Also, adding a surfactant (Tween 20) helped to reduce the emulsion size significantly during microfluidization, but it lead to extensive flocculation of emulsion droplets because of surfactant–biopolymer interactions and emulsifier displacement. [ABSTRACT FROM AUTHOR]

This paper presents results on the preparation of microcapsules containing liquid organosilica, and their co-deposition with copper in an acidic copper electrolyte onto a carbon steel cathode to form a copper/microcapsule composite coating. Microscopic analyses of the surface and the cross-section of the coating confirm the incorporation of the liquid-containing microcapsules in the coating layer. The influence of microcapsules in the electrolyte on the cathode polarization, as well as that of process conditions on the microcapsule inclusion, is also discussed. [ABSTRACT FROM AUTHOR]

Abstract The detection of dopamine (DA) has received enormous attention since it is widely recognized as an important neurotransmitter associated with nerve signaling and some diseases. In this work, glucose‐derived carbon nanospheres (CNs) are synthesized by the green hydrothermal approach and are served to modify electrodes for the detection of DA. The CNs were successfully synthesized and were investigated in detail by various characterization technologies. The CNs modified glassy carbon electrode (CNs/GCE) exhibits better electrochemical sensing performance with a wide linear range of 0.05–1600 μM and a low limit of 8.3 nM for determination of DA, as compared with the modified electrodes reported previously. The CNs/GCE was successfully applied to detect DA in human serum samples, which makes it promising for a variety of biomedical applications. More importantly, this work shows a novel green and simple strategy for the development of cost‐effective and high‐performance sensing materials, which provides more opportunities for design of electrochemical sensors with future capabilities of mass production in practical applications.