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The consumption of rechargeable batteries has been increasing rapidly. High demand on specific metals for battery manufacturing and environmental impacts from battery disposal make it essential to recycle and retrieve materials from the spent batteries. There have been some review articles on battery recycling, mostly on the technologies for the materials recovery and some on life cycle assessment (LCA). To develop a truly sustainable battery industry, however, battery recycling must be commercially viable. Yet, very limited information on the economics of battery recycling is available. This paper examines technologies and research efforts in battery recycling from the perspective of economic viability and life cycle inventory. With the support of up-to-date statistics, the paper also comments on the challenges facing battery recycling, and the role of battery design and circular economy in the sustainable development of battery industry where governments, manufacturers and consumers all play a part.

A series of novel bifunctional catalysts (SrO–ZnO/Al2O3) have been synthesised via the wet impregnation method for biodiesel production. The basic and acidic activities of the prepared catalysts were investigated using corn oil and oleic acid, respectively. Physio-chemical characteristics of the synthesised catalysts were analysed by XRD, SEM-EDS, TGA-DSC, and FT-IR. 1H NMR was used for analysing the fatty acid ethyl ester and the free fatty acid. The catalyst exhibited higher catalytic activity in transesterification reaction, with 95.1% reaction conversion at operating conditions of 10:1 ethanol to corn oil molar ratio, 10 wt% catalyst loading, and 180 min at 70 °C. However, the conversion for esterification reaction was 71.4% at operating conditions 5:1 ethanol to corn oil molar ratio, 10 wt% catalyst loading, 6 h reaction time at 70 °C reaction temperature. The kinetic studies revealed that the transesterification and esterification reactions have good agreement with the first-order model.

A simultaneous transesterification and esterification process was applied for production of biodiesel from high acidic waste cooking oil containing 18 wt% FFA using a range of heterogeneous bifunctional strontium–zinc–aluminium catalyst. The influence of the molar ratio of metal oxide, the ethanol to waste oil molar ratio, temperature and time of reaction, catalyst dosage, and free fatty acids in the feedstock on the conversion of biodiesel were studied. High interaction between Sr, Al and Zn metal was recognised to promote catalyst performance. A high interaction and mixing of strontium, aluminium and zinc oxides enhanced and increased the active sites on the surface of acid and base. The catalyst with a 2.6:1 M ratio of strontium to zinc was found to perform the best to transesterify the glycerides and esterify the fatty acid in the used oil simultaneously. The catalyst exhibited higher catalytic activity with high acidity waste cooking oil, with 95.7% reaction conversion at the optimum conditions 10:1 ethanol to waste oil molar ratio, 15 wt% catalyst dosage, and 5 h reaction time at 75 °C reaction temperature. The used catalyst showed low reusability due to high leaching of strontium.

Nitrate is one of the most common contaminants in food and the environment and mainly arises from intense human activities. Electrochemical sensors have been considered as one of the most promising analytical tools for the rapid detection of nitrate in food and environmental matrices due to their quick response, high sensitivity, ease of operation and miniaturisation, and low sample and power consumption. In this review, we summarise advances in sensors for electrochemical analysis of nitrate over the past decade. We also discuss the application of electrochemical sensing systems for the determination of nitrate in the matrices of fresh water, seawater, food, soil and particulate matter.

Scale-up of any engineering process is a great technical and economic challenge. Scale-up of granulation processes, in particular, is difficult and often problematic due to the inherently heterogenous nature of the materials used. However, recent improved understanding of the rate processes that control granulation improves our ability to do rational scale-up.

S and As are common impurities in refractory gold ores and must be removed before gold extraction. Thermodynamic analyses show that it is possible to simultaneously remove S and As by an O2-enriched single-stage roasting, which is confirmed with experimental results from roasting of a gold refractory ore. The range of optimal O2 requirement is narrow and varies with the S and As content in the ore. Both the extent of removal of S and As, and the subsequent recovery of gold achieved from the optimized single-stage roasting are comparable to those attained from two-stage roasting processes.

To explore the clinical significance of G6PD gene mutation detection in female heterozygote with G6PD deficiency.G6PD activity and fourteen common G6PD gene mutations in female blood samples were detected by biochemical phenotype detection and PCR-reverse dot blotting, respectively. Unidentified genotype of G6PD positive samples was further ascertained by direct DNA sequencing. The results from two methods were compared and analyzed.A total of 493 unrelated females were enrolled, and the G6PD activity and G6PD mutations was detected. Among them, 473 females were found to be normal in G6PD activity and 20 females with G6PD deficiency, and the detection rate by G6PD activity method was 4.06%. In all enrolled females, G6PD gene mutations, including the mutation of c.1311 C＞T, were identified in 130 females, and the detection rate was 26.3%. Detection rate of the mutations that can lead to G6PD deficiency was 8.11%. The detection rates between the two methods were significantly different (P＜0.01). The misdiagnosis rate of the G6PD activity detection reached 49. 94% for the female heterozygotes. Eight G6PD mutations and 13 mutation patterns were identified in the research, and most of mutation patterns were single nucleotide missense mutation. In addition to c.1311C＞T mutation, the most common mutations were c.1376G＞T, c.1388G＞A and c.95 A＞G. G6PD mutations were identified in 19 of 20 females with G6PD deficiency, and were also detected in 21 of 473 females with normal G6PD activity, of which the rate of heterozygous mutation was 90.88%.The phenotype detection based on G6PD enzyme activity alone is not sufficient for the diagnosis of female heterozygotes. The detection of G6PD mutations that covers the common mutations in specified region can effectively identify the female heterozygotes with normal G6PD activity.葡萄糖-6-磷酸脱氢酶缺乏症女性杂合子基因突变检测的临床意义.探讨基因突变检测在检测葡萄糖-6-磷酸脱氢酶 (G6PD) 缺乏症女性杂合子中的临床价值.采用G6PD活性生化表型检测方法和核酸扩增导流杂交基因检测法对无血缘关系的女性血液标本分别进行G6PD活性检测和常见14种突变基因检测, 对未检测到基因突变的G6PD阳性样本进行测序检测分析, 对2种检测结果进行分析比较.无血缘关系的女性体检者共493例接受检测, 其中酶活性正常473例, 酶活性降低20例, G6PD酶活性降低检出率为4.06%。全部受检女性中, 130例女性检出G6PD基因突变, 包括c.1311 C＞T突变在内检出率为26.37%, 致病基因突变检出率为8.11%, 2种方法对女性G6PD缺乏症检出率有明显差异 (P＜0.01) , G6PD酶活性检测可造成49.94%女性杂合子漏检。本研究共检出8种基因突变13种突变变异型, 大多为单核苷酸替代错义突变, 除单纯c.1311 C＞T突变之外, 最常见突变为c.1376G＞T、c.1388G＞A、c.95 A＞G 3种突变。20例G6PD活性降低女性人群中，19例检测到致病基因突变, 473例G6PD活性正常女性人群中, 21例检测到致病基因突变, 杂合子基因突变占90.88.G6PD酶活性检测不足以满足女性杂合子检测需要, 采用覆盖本地区常见基因突变类型的基因检测方法可有效鉴定酶活性正常G6PD缺乏症女性杂合子人群.

In this paper, E-h-pH and speciation diagrams for gold leaching in the Co-NH3-S2O32--H2O system are constructed from thermodynamic calculations. The diagrams show that thermodynamically stable redox couples of Co(NH3)(6)(3+)/Co(NH3)(x)(2+) (x = 1-6) can be formed and drive the dissolution of gold in ammoniacal thiosulphate solutions. Based on the diagrams, a possible mechanism for the Co(III)/Co(II) electrochemical-catalytic leaching of gold with ammoniacal thiosulphate is proposed. The calculation also reveals the differences in the oxidization potential and structural stability of the Co(NH3)(6)(3+) and Cu(NH3)(4)(2+), which explains the much reduced thiosulphate consumption in the Co-NH3-S2O32--H2O system compared to that in the Cu-NH3-S2O32--H2O system. Results presented in this paper offer a theoretical basis for the optimization of the cobalt-catalysed thiosulphate leaching of gold.

Two lab-scale wetland systems were studied for the removal of dissolved Cu, Mn, Fe, Pb and Zn. Vegetated with Typha domingensis , each system consisted of two units, a vertical and a horizontal flow wetland column, which were filled with either crushed sea shell grits or composted green waste as main media. A synthetic acidic wastewater was prepared by dissolving H 2 SO 4 , Pb(CH 3 COO) 2 , MnCl 2 , FeSO 4 , CuSO 4 and ZnSO 4 in a distilled water. As it passed through each column, metal concentrations, pH and conductivity were monitored. The pH value of the wastewater increased in the shell grit columns, where dissolved metals were almost completely (>99%) removed. In the wetland columns filled with the green waste, the average percentage removals were 90, 77, 27, 98 and 75% for Cu, Mn, Fe, Pb and Zn, respectively. Scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) analysis showed that the surface characteristics of the shell grits remained largely unchanged before and after being used in the columns; but the mass compositions of carbon increased, whereas calcium and oxygen decreased. Infrared spectroscopy (IR) and X-ray diffraction (XRD) were used to further analyse the chemical compositions and functional groups of the surfaces of the shell grits.

Growing quantities of end-of-life batteries, increasing demand for critical metals and the depleting reserve of high grade ores have necessitated the need to explore secondary sources such as spent lithium ion batteries (LiBs). Among various processes developed for the recovery of materials from the LiBs, the hydrometallurgical approach is mainstream due to its flexibility and efficiency. However, the cost and environmental impacts of hydrometallurgical approaches depend on the reagents used. Organic compounds such as organic acids and biomasses as lixiviants and reductants are considered cheaper and more eco-friendly alternatives to their inorganic counterparts conventionally used. This review summarises the progresses made in the use of organic based substances as reductants in reductive leaching of spent LiBs and low grade ores. It also discusses factors affecting leaching mechanisms, possible reaction chemistries and kinetics. Analysis of the available data in the literature suggests that the use of organic-based compounds could achieve comparable recovery but with much reduced adverse environmental impacts in the extraction of metals from spent LiBs. Further, technology development in the area will benefit from application of key knowledge on the recovery of metals from low grade ores. The review concludes with a summary of current challenges facing the industrial application of organic compounds and highlights future perspectives on organic acids as lixiviants in a mixed acid leaching system.

The sintering behaviors among SiO2, FeS and Fe3O4 were detected to reveal the formation mechanism of Fe2SiO4. The results indicated that the formation mechanism is divided into five steps: (1) migration of O2− induced by S2− under a reducing atmosphere; (2) formation of Fe3O4−β ; (3) migration of Fe(II) into a ferrite cluster structure to gain oxygen and form Fe3−x O4; (4) Fe(II) invaded the silicon atomic position and released Si(IV); and (5) formation of the stable structure of Fe2SiO4 through chemical diffusion between cations of Fe(II) and Si(IV). These findings can provide theoretical support for controlling the process of the recovery of valuable metals in copper slag through the combined roasting modification–magnetic separation process.

Liquid templating is a well-established method for the fabrication of monodisperse microparticles. Nearly all liquid templating methods use totally immiscible liquids for the generation of monodisperse liquid droplets. With this approach, it is difficult to mass produce monodisperse droplets in the submicron range. The approach also suffers from some common difficulties associated with the use of small openings or channels required for the generation of small sized droplets including high back pressures and frequent blockage of the flow channels. Aimed at overcoming these difficulties, this paper presents a new co-flowing method that uses partially miscible liquids for the generation of a monodisperse liquid template. The results show that addition of a co-solvent in the inner phase that makes the liquid systems partially miscible changes the bulk and interfacial properties of the liquids that facilitate the generation of smaller droplets. They also confirm that the co-solvent concentration in the inner phase can be used as an additional tool to manipulate the mean size of the resultant droplets and solid particles.

Arsenopyrite (FeAsS) is the most common As-containing sulphide mineral in gold deposits. Most auriferous arsenopyrite ores are refractory necessitating pre-treatments before gold extraction. Bio-oxidation pre-treatment is simple and eco-friendly technology that has attracted significant attention in the past decade. Slow leaching kinetics of bioleaching is, however, a critical impedance to its large-scale application. The addition of metal cations has previously been found to expedite the leaching process. The electrochemical behaviour of Ag+ in the dissolution of arsenopyrite in 9 K culture medium was investigated in depth by a series of electrochemical and analytical techniques. Electrochemical results suggested that Ag+ could significantly improve the oxidative dissolution of arsenopyrite. Analytical results demonstrated that, with Ag+, only a discontinuous, porous and non-passivating film was formed on the arsenopyrite surface. The catalytic effect of silver is largely attributed to that Ag+ can enhance the oxidative dissolution of not only arsenopyrite but also the passive film by forming conducting Ag2S on the arsenopyrite surface, which explains why Ag+ can remove the passive film on the surface of arsenopyrite during bioleaching and thus effectively shorten its bioleaching period.

In the present work, the (100 − x)(58SiO2-20Fe2O3-10B2O3-12Na2O) − xAs (x = 0, 2, 4, 6, 8 wt%) glasses, which are main constituents of the copper slag based glasses, were produced by conventional melting method to study the arsenic vitrification mechanism and stability. X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR) and X-photoelectron spectroscopy (XPS) were used to investigate the mechanism of arsenic vitrification. The XRD analysis for the x ≤ wt 8% samples shows that all the samples form homogeneous glasses and the arsenic is compatible with the copper slag based glass. The FTIR spectrum of the glasses have revealed that the arsenic exists in the form of AsO4 tetrahedra and the Qn structure of the copper slag based glass has been strengthened with the increase addition of arsenic. The changes of the binding energies of Si2p, O1s, As3d and Fe2p directly indicate the formation of Si O As and Fe O Si/As bonds in the glass, which strengthens the chemical stability of the glass. Lastly, USEPA toxicity characteristics leaching procedure (TCLP) and differential scanning calorimetry (DSC) tests were used to study the chemical durability and thermal stability of the glasses containing arsenic. The leaching concentrations of As, B, Fe, Na, and Si are under safety thresholds and the increase addition of arsenic into the glasses can decrease the leaching concentrations, indicating that the arsenic can improve the chemical stability of the glass. The arsenic added into the glass can improve the ΔT, which strengthens the thermal stability of the glasses.

Monodisperse microparticles find applications in a wide range of areas. Generation of such particles of several microns in size at a large scale is a difficult task. This paper reports a proof of concept using a microfluidic device that coaxially flows partially miscible liquids for the production of microparticles. The approach makes use of both the physical forces of the process and the chemical properties of the liquid systems that allows for careful control of the mixing and droplet formation processes. Initial results show that, with this approach, particles with a reasonably narrow size distribution can be produced and liquid miscibility can be used as an additional avenue to manipulate the mean particle size and morphology.

A novel process for extracting transition metals, recovering lithium and regenerating cathode materials based on facile co-extraction and co-precipitation processes has been developed. 100% manganese, 99% cobalt and 85% nickel are co-extracted and separated from lithium by D2EHPA in kerosene. Then, Li is recovered from the raffinate as Li2CO3 with the purity of 99.2% by precipitation method. Finally, organic load phase is stripped with 0.5M H2SO4, and the cathode material LiNi1/3Co1/3Mn1/3O2 is directly regenerated from stripping liquor without separating metal individually by co-precipitation method. The regenerative cathode material LiNi1/3Co1/3Mn1/3O2 is miro spherical morphology without any impurities, which can meet with LiNi1/3Co1/3Mn1/3O2 production standard of China and exhibits good electrochemical performance. Moreover, a waste battery management model is introduced to guarantee the material supply for spent battery recycling.

To ascertain the role of natural fermentation and its associated microorganisms in the eating quality of fermented rice noodles, we compared changes in main chemical components, microorganisms, and eating qualities of fermented rice noodles compared with unfermented ones. The results indicated that noodles made from rice grains fermented at 40°C have higher tensile strength, hardness, springiness, and chewiness. Statistical analyses show that fermentation significantly changed the content and composition of the starch, lipid, protein, amylose, and ash of the indica rice. High-throughput sequencing analyses of the supernatant of the fermentation samples revealed the dynamic changes of the bacteria population during fermentation. Lactic acid bacteria are found to be the dominant bacteria (more than 90%) during the entire process. The relatively high abundance of Lactobacillus fermentum and L. delbrueckii at each phase of the fermentation suggests that the two species are likely to be the species that determ...

In this study, the PIV and flow visualization techniques and three-dimensional direct numerical simulation are used to investigate the behavior of triple transitional round fountains, which are aligned along a straight line, interacting with each other in a homogeneous fluid over the ranges of 1 ≤ Fr ≤ 10 and 100 ≤ Re ≤ 1000, at a fixed spacing of D / X 0 = 6 , where Re and Fr are the Reynolds and Froude numbers, D is the spacing between the two neighbouring fountain sources, and X0 is the radius of orifices at the fountain source, respectively. The results show that the interaction behavior of triple transitional round fountains, over the ranges of Re and Fr studied, is dominated by the bobbing and flapping motions, and is either steady, or unsteady weakly multi-modal, or unsteady strongly multi-modal. In a steady interaction, the bobbing-flapping motions are only present in its initial development stage and the interaction will attain a steady state in the later stage in which the bobbing-flapping motions are no longer present. In contrast, in an unsteady interaction, the interaction remains unsteady all the time and the bobbing-flapping motions are present at all stages. Among all cases considered, a steady interaction occurs at Re ≤ 300 with F r = 1 and at R e = 100 with Fr ≤ 5; an unsteady weakly multi-modal interaction occurs at R e = 100 with 6 ≤ Fr ≤ 10, at 200 ≤ Re ≤ 300 with 2 ≤ Fr ≤ 10, and at R e = 400 with F r = 1 ; and an unsteady strongly multi-modal interaction occurs at 600 ≤ Re ≤ 1000 with F r = 1 and at 400 ≤ Re ≤ 1000 with 2 ≤ Fr ≤ 10. Such interaction behavior is found to be similar to that of twin transitional round fountains over comparable ranges of Re and Fr, as discovered by us in an earlier study. It is also found that the two interaction regions formed by the three fountains have essentially symmetrical behavior about the middle fountain for all cases considered. Furthermore, the maximum fountain penetration heights and the maximum thicknesses of the interaction regions of the triple transitional round fountains are quantified with the experimental and numerical results and compared to the available scalings for single fountains at comparable Fr and Re values. Several scaling relations are then developed for these parameters over the ranges of Fr and Re considered.

In this paper, a process based on reducing thermal treatment before acid leaching for the recovery of valuable materials from spent lithium-ion batteries is developed. The thermodynamic behavior of the active cathode materials is investigated through analyzing the gases evolved from the thermal treatment with a thermogravimetric–mass spectrometry (TG–MS) instrument. Scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) spectroscopy analyses are also performed on the solid cathode and anode materials to determine their physicochemical changes from the thermal treatment. The results show that the thermal treatment significantly improves the clean separation of the active materials from the current collectors and the complete removal of the binder and carbonaceous conductor. It also alters the molecular structures of, and partially reduces the transition metals in, the active cathode materials, which increases the leaching efficiency of the transition metals in the subsequent leaching step. After thermal treatment, the leaching efficiency of nickel, cobalt and manganese from the active cathode materials has reached over 98%, 99% and 84%, respectively.

To reduce the cost of the complex separation process of nickel, cobalt or manganese from the leaching liquid, a high value-adding process for the direct synthesis of LiNi0.8Co0.1Mn0.1O2, LiNi0.5Co0.2Mn0.3O2 and LiNi0.33Co0.33Mn0.33O2 as active cathode materials by the hydroxide co-precipitation method is developed in this paper. The structure, morphology and composition of the regenerated LiNixCoyMn1-x-yO2 cathode materials are determined with X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectrometry (ICP–AES) and energy dispersive X-ray spectroscopy system (EDXS), respectively. The results show that the regenerated cathode materials have a well-defined layered structure and retain the characteristics of their corresponding hydroxide precursors with a spherical morphology and a particle size in the range from 9 to 12 μm in diameter. Electrochemical tests show that the regenerated cathode materials have good electrochemical performances. The initial discharge capacities (0.1C, 2.7–4.3 V) of the regenerated LiNixCoyMn1-x-yO2 are 197.7 mAh g− 1, 174.3 mAh g− 1 and 168.3 mAh g− 1 for x = 0.8, 0.5 and 0.33, respectively. The discharge capacities of all materials decrease with increasing discharging current densities and the capacity retention ratios of LiNi0.8Co0.1Mn0.1O2, LiNi0.5Co0.2Mn0.3O2 and LiNi0.33Co0.33Mn0.33O2 are 86.3%, 95% and 96% respectively after 50 cycles. Overall, the results show that the performances of regenerated LiNixCoyMn1-x-yO2 are similar to those of the materials prepared from mixed solution of virgin nickel, cobalt and manganese chemicals.

Microfluidics has been an active research field and an indispensable tool for quantitative analyses of chemicals and biological specimens for decades. Its widespread application stems from its ability to accurately handle small quantities of samples and its well-controlled environments. Further developments of microfluidics require a fundamental understanding of fluid dynamics and associated phenomena. This chapter provides some basic descriptions of fluid properties and principles that govern the flows inside the channels of a microfluidic device. It also examines relevant dimensionless numbers used for the understanding of the flow and the design and scale-up of microfluidic devices. The chapter concludes with suggestions on key areas of importance for future research in microfluidics.

When a fountain is injected into a linearly stratified fluid, its behavior will be governed by the stratification of the ambient fluid, represented by the dimensionless temperature stratification parameter (s), in addition to the Reynolds number (Re) and the Froude number (Fr). In this study, a series of three-dimensional direct numerical simulations (DNS) were carried out using ANSYS Fluent for transitional plane fountains in linearly-stratified fluids with Re, F r and s over the ranges 28 ≤ Re ≤ 300, 3 ≤ F r ≤ 10, and 0.1 ≤ s ≤ 0.5 to study the effects of these governing parameters on the characteristics of such unsteadiness. Empirical correlations to quantify the effects of F r, Re and s over the studied ranges on the characteristics of the unsteadiness are also obtained and compared to the relevant scaling relations developed for weak plane fountains. Keywords: Direct numerical simulation, Plane fountain, Stratification, Transitional flow, Unsteadiness.

Hydrogen permeation of nanostructured bainitic steel, produced at two different transformation temperatures, i.e., 473.15 K (200 °C) BS-200 and 623.15 K (350 °C) BS-350, was determined using Devanathan–Stachurski hydrogen permeation cell and compared with that of mild steel. Nanostructured bainitic steel showed lower effective diffusivity of hydrogen as compared to the mild steel. The BS-200 steel, which exhibited higher volume fraction of bainitic ferrite phase, showed lower effective diffusivity than BS-350 steel. The finer microstructural constituents (bainitic ferrite laths and retained austenite films) and higher dislocation density in the bainitic ferrite phase of BS-200 steel can be attributed to its lower effective diffusivity as compared to BS-350 steel and mild steel.

Nanostructured NiO/C composite particles with controlled carbon content for lithium-ion battery anode were prepared via a one-pot hydrothermal approach and subsequent calcination in a high purity nitrogen atmosphere. The composites were composed of amorphous carbon and nanocrystalline NiO. The structure of the NiO crystals was determined with X-ray diffraction (XRD) analysis and the content of carbon was calculated from the energy dispersive spectroscopy (EDS) results. Scanning electron microscopy (SEM) images showed a relatively narrow distribution of particle size for both the neat NiO and NiO/C nanoparticles. Electrochemical performance measurements demonstrated that, after 50 cycles, NiO/C nanocomposites maintained a high reversible capacity of 585.9 mAh g−1, much higher than that of 356.1 mAh g−1 of the neat NiO nanoparticles without carbon. The NiO/C nanoparticles also exhibited a remarkable discharge capacity, a high charge/discharge rate and an excellent cycle stability. The improvements can be attributed to the even carbon coating on the NiO particles, which significantly enhances the conductivity and improves the structural stability of the electrode.

Fountains injected into stratified fluids are widely found in environmental and industrial settings. The onset of asymmetry and entrainment that occurs in transitional fountains is the key to understanding turbulence generation and entrainment mechanisms in fountains. In addition to the Reynolds number ( Re ) and the Froude number ( Fr ), the stratification of the ambient fluid, represented by the dimensionless temperature stratification parameter ( s ), also has a significant effect on the onset of asymmetry, unsteadiness, and entrainment in a fountain, and on the maximum height that the fountain penetrates in the ambient fluid. In this study, a series of three-dimensional direct numerical simulations (DNS) were carried out using ANSYS Fluent for transitional plane fountains in linearly-stratified fluids with Re and s in the ranges of 25 ⩽ Re ⩽ 300 and 0 ⩽ s ⩽ 0.5 , all at Fr = 10 . The transient behavior of the fountains, in particular the effects of Re and s on the asymmetric transition and the maximum fountain penetration heights, is analysed and quantified using the DNS results. It is found that fountains are generally symmetric in the early developing stage, but become asymmetric and unsteady subsequently. The stratification of the ambient fluid is shown to stabilize the fountain flow and to reduce its asymmetry and unsteadiness. However, the effect of s on the asymmetric behavior of a fountain is found to be weaker than that of Re . Empirical correlations were developed, using the numerical results, to quantify such effects on the time for the asymmetric transition. The effects of Re and s on the initial and time-averaged maximum fountain heights ( z m , i and z m , a , respectively), and the time to attain z m , i are also analysed. Quantified correlations are developed using the DNS results, which demonstrate that both z m , i and z m , a increase with Re , but decrease with s , apparently due to the increasing negative buoyancy that the fountain must overcome to penetrate the ambient fluid. The results further show that the effect of s on z m , i and z m , a is much stronger than that of Re .

Thiosulphate, as an environmentally friendly lixiviant, is currently identified as the most promising alternative to cyanide for the extraction of gold from ores in sensitive locations. The Cu(II) ammine complexes acts as the catalytic oxidant to increase the thiosulphate leaching rate of gold, which also causes an undesirable high consumption of thiosulphate. Due to the complex solution chemistry of Cu–NH3–S2O32−–H2O system, fundamentally supported mechanisms to justify the catalytic effects and the consumption of thiosulphate are yet to be developed. Thermodynamic analysis offers essential information on which chemical species that could form and how these species influence the solution chemistry under various conditions. In this paper, predominance area and species distribution diagrams for gold leaching in the Cu–NH3–S2O32−–H2O system were constructed from a series of calculations using updated thermodynamic data. The diagrams reveal insights into the thermodynamics of gold dissolution, thiosulphate stability and redox behaviour of Cu(II)/Cu(I) couples. Analysis of the results presented in this paper can provide a theoretical basis for the complex thiosulphate leach solution chemistry that allows for a better understanding on the relationships between the redox behaviour of Cu(II)/Cu(I) couples and the behaviours of gold leaching and thiosulphate decomposition.

Bioleaching pre-treatment of arsenopyrite (FeAsS), a common mineral occurring in deposits of gold ore that makes the extraction of gold difficult, has attracted significant attention recently due to its simple operation and environmental friendliness. A critical impedance of bioleaching to its large scale industrial application is the slow leaching kinetics. Several metal cations have previously been found to accelerate the leaching process. This paper reports results from an in-depth investigation into the bioleaching of arsenopyrite including leaching experiments, thermodynamic analysis of the leaching system and physicochemical analyses of the materials. The results suggest that a passivating film consisting mainly of As2S2, As2S3 and S0 formed on the arsenopyrite surface in the initial bioleaching of 36 h in the 9K culture containing Acidithiobacillus ferrooxidans. This film disappeared when Cu2+ was added to the system. The bioleaching of arsenopyrite was efficiently improved at the Cu2+ level of 0.05 g/L with its leaching period significantly shortened from 19 d to 13 d. Based on the results, the paper also proposes possible leaching mechanisms and the role of Cu2+ in improving the rate of the leaching process. Specifically, Cu2+ is found to facilitate the oxidative dissolution of the passivating species of As2S2, As2S3 and S0 by forming Cu2S/CuS that can be rapidly oxidised by Fe3+ back to Cu2+. A catalytic cycle of Cu2+/(Cu2S/CuS) is thus likely established on the Fe3+/Fe2+ catalytic cycle, resulting in the elimination of the passivating film. The bacteria utilised the two synergistic cycles to catalyse the leaching of arsenopyrite.

The behaviour of arsenopyrite (FeAsS) in the acidic iron-free 9K culture medium was investigated using a combination of electrochemical and analytical techniques. The results demonstrated that the oxidative dissolution of arsenopyrite was accompanied by its surface passivation from the beginning of the arsenopyrite dissolution at potentials from OCP to 1000 mV, which limited further dissolution of arsenopyrite. The dissolution was complex and different under different applied potentials. The leaching kinetics of Fe, As and S, as well as the physicochemical properties of the formed passive film, varied with the potentials. A dissolution rate was found to be likely Fe > As > S from FeAsS. The passive film consisted mainly of As2S2 and As2S3 (≤800 mV), and S0 (>800 mV). The passive film was also shown to have a two-layer structure, i.e. a porous outer layer and a compact inner barrier layer that appeared to impart its strongest resistance to the dissolution of arsenopyrite at 750 mV. An applied potential higher than 800 mV could observably improve the dissolution of the film and thus reduce its passivating action.

Rational design and facile synthesis of hybrid TiO2 anode materials with high electrical conductivity and ionic accessibility are urgently desired to construct high performance litium-ion batteries. In this work, We first utilize conductive hollow porous pollen carbon microsphere as skeleton to load C@TiO2 nanoparticles. The C@TiO2/3D pollen carbon (CTPC) composite with hollow porous structure has been successfully developed via a simple method. As a result, CTPC-700 (calcination temperature of 700 °C) electrode material exhibits superior electrochemical performance for lithium ion batteries, delivering an outstanding specific capacity of 148 mA h g−1 up to 1000 cycles at 5.0C and a superior high-rate performance of 112 mA h g−1 at 10.0C. Therefore, the special structure of the as-prepared composites can improve the stability of the electrode and enhance its electrochemical performance, which is promising for the next-generation of lithium-ion batteries.

Recent developments in rechargeable battery technology have seen a shift from the well-established Li-ion technology to new chemistries to achieve the high energy density required for extended range electric vehicles and other portable applications, as well as low-cost alternatives for stationary storage. These chemistries include Li-air, Li-S, and multivalent ion technologies including Mg2+ , Zn2+ , Ca2+ , and Al3+ . While Mg2+ battery systems have been increasingly investigated in the last few years, Ca2+ technology has only recently been recognized as a viable option. In this first comprehensive review of Ca2+ ion technology, the use of Ca metal anodes, alternative alloy anodes, electrolytes suitable for this system, and cathode material development are discussed. The advantages and disadvantages of Ca2+ ion batteries including prospective achievable energy density, cost reduction due to high natural abundance, low ion mobility, the effect of ion size, and the need for elevated temperature operation are reviewed. The use of density functional theory modeling to predict the properties of Ca-ion battery materials is discussed and the extent to which this approach is successful in directing research into areas of promise is evaluated. To conclude, a summary of recent achievements is presented and areas for future research efforts evaluated.

This paper is the second part of our study on the behavior of the interaction between twin transitional round fountains with equal power in a homogeneous fluid. In the first part (Mahmud et al., 2015), an experimental study using PIV techniques and flow visualization was carried out over the ranges 1⩽Fr⩽5 and 25⩽Re⩽400, where Re and Fr are the Reynolds and Froude numbers, respectively. In the current paper, this work is extended to wider ranges, i.e., 1⩽Fr⩽10 and 25⩽Re⩽1000, by a series of three-dimensional direct numerical simulation (DNS). In addition, a preliminary study on the effect of the distance between the two fountain sources is also carried out for three representative cases. The DNS results are found to capture all the major features of the steady, and unsteady weakly multi-modal and strongly multi-modal interaction behavior, which is dominated by bobbing and flapping motions, as found by the experimental study (Mahmud et al., 2015), but over wider ranges of Fr and Re. Furthermore, the maximum fountain penetration height and the maximum thickness of the interaction region, obtained with the DNS, together with the experimental results of (Mahmud et al., 2015), are quantified and compared to the available scalings for single fountains in a homogeneous fluid at comparable Fr and Re values, and several scaling relations are then developed for these parameters over the ranges of Fr and Re considered in the current study.

Spherical Ni1/3Co1/3Mn1/3(OH)2 agglomerates were synthesized by the co-precipitation method in the presence of ammonia. The results show that the growth mechanism of spherical agglomerates follows three-stages, i.e. nucleation and anisotropic growth of single crystals; agglomeration of polycrystalline crystallites agglomerated by single crystal grains as primary particles to form embryonic agglomerates; formation, growth and consolidation of spherical agglomerates or particles by agglomeration of embryonic agglomerates, continued growth of individual crystals in the agglomerates and further attachment of primary particles. The first two stages are very fast while the last stage takes almost the entire process to complete. The main reason for the anisotropic growth of Ni1/3Co1/3Mn1/3(OH)2 crystal is that crystal surface energy of E(001), E(100), E(101) and E(102) is different with E(001) being the highest. The morphology of the final spherical agglomerates is explained by partial re-crystallization of contacting primary particles. The growth process of spherical agglomerates was examined by X-ray diffraction, scanning electron microscope, transmission electron microscope and calculation of crystal surface energy using density function theory.

Nanodroplets on a solid surface (i.e. surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, lab-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 that the contact angle of the nanodroplets is independent of the flow condition. However, there are 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 gives that the volume of the nanodroplets increases with the Peclet number $Pe$ of the flow as $\propto Pe^{3/4}$, 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., 24 pages, 5 figures

The pasting properties of rice flours and reconstituted rice flours from mixing a common starch with proteins extracted from different rice cultivars at different total protein content levels were studied. Results showed that not only the total protein content but also the protein composition had an effect on the pasting properties of the rice flours. Among the different strands of rice proteins, globulin had the strongest influence on the pasting properties, followed by glutelin, whereas prolamin had the least influence. At the subunit level of the proteins, proteins with a molecular weight of 17,000, most likely from globulin, had the strongest effect on the peak viscosity of the rice flour, followed by those of 33,000. In comparison with that of the rice starch, the influence of proteins in rice was limited. The effect of interactions between the rice proteins and the starch, such as the role of starch-granule-associated proteins, was not isolated in this study, and further investigation is re...

The aim of this study was to investigate whether the cathodic activity of magnesium alloys plays a significant role on the electrochemical deposition of calcium phosphate (CaP). CaP was deposited electrochemically on two magnesium alloys, i.e., magnesium–calcium (Mg–Ca) and magnesium–aluminium–zinc (AZ91), with different electrochemical degradation behaviour. The in vitro degradation behaviour of the CaP coated samples was evaluated using electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The polarisation resistance (RP) of the CaP coated Mg–Ca alloy was ~85% lower than that of the CaP coated AZ91 alloy. Fourier transform infrared (FTIR) analysis showed no difference in the chemical nature of the coatings. However, scanning electron microscopy (SEM) analysis revealed that the coating particles on Mg–Ca alloy were less densely packed than those on the AZ91 alloy. This can be attributed to the higher dissolution rate of Mg–Ca alloy as compared to AZ91 alloy. As a result, the former exhibited higher cathodic charge density which produced higher hydrogen evolution, thereby affecting the coating process.

Li1.8MnSi0.8P0.2O4 prepared by a citrate acid assisted sol–gel route followed by calcination at 800 °C is compared to a sample of standard Li2MnSiO4 prepared under the same experimental conditions. The particle size of the P-substituted material is 20–40 nm compared to 50–100 nm for the P-free sample. Rietveld refinement of crystallographic models with synchrotron powder X-ray diffraction data shows that both samples consist of a mixture of the Pmn21 and Pmnb polymorphs of Li2MnSiO4 and a minor MnO impurity (< 5%). In the P-substituted material, P is found to partially replace Si in the Pmn21 polymorph accounting for the PO43 − bands observed in the FTIR spectra. The lattice parameters of the P-substituted material differ only slightly from those of the P-free material. Electrochemical tests show that Li/Li1.8MnSi0.8P0.2O4 cells have better performance than Li/Li2MnSiO4 cells in terms of reduced polarisation and a 66% better initial discharge capacity at 40 mA g− 1. P-substituted samples show some loss in long-range order with cycling but less than that observed in P-free samples. Significant reflections are observed in P-substituted cathode samples in the discharged state after the first cycle, in contrast to P-free material. This shows that P-substituted cathodes are less prone to amorphisation than standard P-free cathodes.

Lithium ion batteries are under intense development to meet the performance specifications for consumer applications in portable electronic devices, electric vehicle batteries and stationary storage as back-up for intermittent renewable energy generation technologies. The most expensive and capacity-limiting component in these battery systems is the cathode material. Research has been directed to the development of novel cathode materials with high capacity and energy density and the lithium transition metal orthosilicates have been identified as possible high performance cathodes. In this review we focus on recent developments in the study of Li2MnSiO4 and its derivatives as a lithium-ion battery cathode material. Preparation techniques, structural issues, conductivity enhancement and complex morphologies are discussed, to show the recent improvements and limitations in synthesis and electrochemical performance.

Mesoporous electrode materials are favourable for lithium-ion batteries as they have high surface area and provide short lithium-ion diffusion distances from the pore space into the thin pore walls. The porous morphology is also an advantage for buffering the large volume changes that can accompany lithium insertion and extraction. For this reason, this study investigates the synthesis of mesoporous lithium manganese silicate, using mesoporous silica as a template. It is shown that a mesoporous lithium manganese silicate product, retaining the mesoporous symmetry of the SBA-15 silica precursor, can be formed by emulsion synthesis followed by calcination in an inert atmosphere at 700 °C. These calcination conditions retain the decomposed surfactant as a conductive surface layer on the product phase. Undesired, electrochemically inactive MnO impurities were minimized by reducing the Li : Mn ratio to 2 : 0.7 in the starting mixture. Rietveld analysis of the X-ray diffraction patterns of the product shows that it is manganese deficient with composition Li2Mn0.87(3)SiO4 with minor impurities of MnO and Li2SiO3. Excellent reversibility is observed for these cathodes in lithium cells with a capacity of 175 mA h g−1 when cycled in constant current–constant voltage mode at a current rate of 20 mA g−1.

In this study, the in vitro degradation behaviour of AZ91 magnesium alloy with two different surface finishes was investigated using electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF). The polarisation resistance (Rp) of the rough surface alloy immersed in SBF for 3 h was ~30% lower as compared to that of the smooth surface alloy. After 12 h immersion in SBF, the Rp values for both the surface finishes decreased and were also similar. However, localised degradation occurred sooner, and to a noticeably higher severity in the rough surface alloy as compared to the smooth surface alloy.

The electrochemical corrosion behaviour of WE54 magnesium alloy in 0.5 wt.% NaCl solution was studied using electrochemical techniques. Polarization results suggested that the rare-earths in WE54 alloy enhanced the passivation tendency of the alloy and decreased the corrosion current by ~30% compared to pure magnesium. Pitting corrosion resistance was also higher in WE54 alloy than that in pure magnesium. Long-term electrochemical impedance results showed that the polarization resistance of WE54 alloy was more than two times higher than that of pure magnesium even after initial passivity breakdown.

The Mn valency and the crystallinity of Li 2 MnSiO 4 cathodes ( Pmnb form) were examined with electron energy-loss spectroscopy (EELS) and selected area electron diffraction (SAED) both before and after electrochemical lithium extraction. A decrease in the crystallinity of the delithiated charged cathode particles compared to the as-prepared material was observed. The decrease in crystallinity varied from particle to particle. EELS analysis showed that the non-uniform decrease in crystallinity was due to a non-uniform extraction of lithium from the particles. The observed decrease in discharge capacity of the Pmnb polymorph of Li 2 MnSiO 4 with cycling was attributed to the progressive loss of crystallinity and the structural collapse of Li diffusion pathways.

Li(1.0)[Li(1/7)Mn(4/7) Ni(2/7)]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 Li(1.25(3))Ni(0.17(1)) Mn(0.61(1))O₂, close to the well-characterized Li(1.2)Ni(0.2)Mn(0.6)O₂ composition can be described as an intergrowth structure of Li₂MnO₃ and LiMn(0.5)Ni(0.5)O₂ domains and the second phase is a lithium-deficient layered structure with refined composition Li(0.85(1))Ni(0.57(1))Mn(0.55(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.