Biomass-derived carbons for sodium-ion batteries and sodium-ion capacitors

In the past decade, the rapid development of portable electronic devices, electric vehicles, and electrical devices has stimulated extensive interest in fundamental research and the commercialization of electrochemical energy-storage systems. Biomass-derived carbon has garnered significant research attention as an efficient, inexpensive, and eco-friendly active material for energy-storage systems. Therefore, high-performance carbonaceous materials, derived from renewable sources, have been utilized as electrode materials in sodium-ion batteries and sodium-ion capacitors. Herein, the charge-storage mechanism and utilization of biomass-derived carbon for sodium storage in batteries and capacitors are summarized. In particular, the structure–performance relationship of biomass-derived carbon for sodium storage in the form of batteries and capacitors is discussed. Despite the fact that further research is required to optimize the process and application of biomass-derived carbon in energy-storage devices, the current review demonstrates the potential of carbonaceous materials for next-generation sodium-related energy-storage applications.</p

Effect of Nitrate/Bromide on the Hydration Process of Cement Paste Mixed with Alkali Free Liquid Accelerator at Low Temperature

The effects of different inorganic salt accelerators (CaBr2, NaBr, Ca(NO3)2, NaNO3) and an alkali-free liquid accelerator were researched at a low temperature of 10 °C. The results showed the effects of 1.5% NaBr and 1.5% NaNO3 inorganic accelerator were pronounced. The 1-d compressive strengths of the mortar with these two inorganic salts were increased by 185.8% and 184.2%, respectively, and the final setting times were shortened from 7.74 to 6.08 min and 6.12 min, respectively. The hydration temperatures at 10 °C were measured, and the promotion effects of the inorganic accelerators were calculated: the relationship between the hydration degree was αAS + NN > αAS + NB > αAS + CB > αAS + CN > αAS. In addition, the reaction of C3A with NaBr and NaNO3 was used to analyze the products in an ettringite phase, i.e., Ca4Al2O6Br210·H2O, 3CaOAl2O3Ca(NO3)2X·H2O. The formation of these phases was detected in the hydration products of the cement paste hydration for 12 h, 24 h, and 28 d. Combined with the mass loss of the ettringite phase at 90–120 °C, determined using TG/DTG, the synergetic acceleration mechanism of the inorganic accelerators was comprehensively inferred

Exploring the factors influencing the abrasion resistance of hydraulic concrete based on underwater steel ball test

Hydraulic structures may be subjected to erosion and damage by high-speed sand carrying water flow in the overflow area, seriously weakening the normal operation of the building. Due to the limited research on the wear resistance of ordinary concrete as a drainage structure, this paper took concrete in actual engineering as examples to study the effects of compressive strength, aggregate ppaper size, sand volume fraction, pore size parameters, water flow velocity, bed load and suspended load content. The results showed that when using the underwater steel ball method for testing, no strong correspondence between concrete abrasion resistance and a compressive strength. The strength grade of concrete was C40 - C55, with similar abrasion resistance. When the compressive strength was close, the abrasion resistance of concrete was 1.42–1.68 times that of mortar. The smaller the difference between the volume fraction of sand and the compact porosity of coarse aggregate, the higher the abrasion resistance. The proportion of 50–100 nm pore size in the pore structure was negatively correlated with the abrasion resistance of concrete, while the fractal dimension of pore volume was positively correlated with the abrasion resistance. When the water flow speed decreased from 1.5 m/s to 1.25 m/s, the abrasion resistance has increased by 97%. The influence of suspended load on concrete abrasion damage was minimal compared to bed load. Comprehensively studies the influence of different factors on the abrasion resistance of concrete, providing theoretical guidance and practical experience for improving the abrasion resistance of concrete

Improving fine molybdenite flotation using a combination of aliphatic hydrocarbon oil and polycyclic aromatic hydrocarbon

Kerosene is widely used as a collector in molybdenite flotation. However, it can only adsorb on molybdenite faces but not on molybdenite edges, which is unfavorable for the flotation of fine molybdenite particles with high edge/face ratios. In this study, kerosene and polycyclic aromatic hydrocarbon (PAH) were combined to form a composite collector to improve fine molybdenite flotation. It was hypothesized that PAH might adsorb on molybdenite edges through its polar group and render them hydrophobic. This composite collector was examined in the flotation of molybdenite particles from different size fractions. It was found that this composite collector improved the flotation of molybdenite particles especially from finer size fractions. Zeta potential measurements and Fourier transform infrared spectroscopy (FTIR) analyses indicate that PAH preferentially adsorbed on molybdenite edges and therefore improved molybdenite flotation. The improvement was more significant for fine molybdenite particles with a high proportion of edges. This study provides new insights in improving fine molybdenite flotation

The influence of Ca2+ and pH on the interaction between PAHs and molybdenite edges

Nonpolar hydrocarbon oils are widely used as collectors for floating molybdenite. However, they can only adsorb on molybdenite faces and not on molybdenite edges, resulting in limited molybdenite recovery, especially in processed water containing a high amounts of Ca. In this study, the influence of Ca and pH on the adsorption of polycyclic aromatic hydrocarbons (PAHs), as part of composite collection on molybdenite edges, was studied. It was found that PAHs could only adsorb on molybdenite edges in the presence of Ca. Ca reacted with molybdenite edges to form CaMoO precipitates. Then, CaMoO precipitates interacted with PAHs to form a structure of π–cation–π by (1) the cation–π interaction, (2) the π–π interaction and (3) the electrostatic interaction. It was also found that CaMoO precipitates on molybdenite edges promoted the adsorption of PAHs. The more the CaMoO precipitates, the easier the PAHs adsorption occurred. As a result, the high amount of Caand low pH enhanced the adsorption of PAHs on molybdenite edges. This study provides insights into reducing the deleterious effect of Ca on fine molybdenite flotation

A New Concept on High-Calcium Flotation Wastewater Reuse

Calcium ions are a kind of unavoidable ions in water. It has the deleterious effect on molybdenite flotation. High-calcium flotation wastewater (HCFW) was reused for flotation circuits after the pretreatment removing Ca2+ in from HCFW. The high cost of wastewater treatment limits HCFW reuse. In this paper, an efficient, innovative, low-cost and environmental-friendly flotation wastewater reuse technology was introduced. XLM, as a composite collector for molybdenite, is a mixture of diesel oil (DO) and polycyclic aromatic hydrocarbons (PAHs). It could reduce the deleterious effects of Ca2+ on the flotation of molybdenite in HCFW. Therefore, this was used to replace the pretreatment removing Ca2+ in from high Ca2+ wastewater and saved the cost of wastewater treatment. When XLM consists of 4 wt % PAHs and 96 wt % DO, it has better adaptability than DO in the different Ca2+ concentration of flotation water. The contact angle measurements indicated that PAHs, as a synergistic component of a composite collector, could adsorb on the edges of molybdenite in the presence of Ca2+ by forming PAHs-Ca2+-MoO42&#8722; structure to increase the contact angle of fine molybdenite particle and reduce the deleterious effects of Ca2+ on the flotation of molybdenite. The industrial-scale test further that demonstrated XLM can improve the molybdenite roughing recovery and grade by 1.8% and 3.46% compared with DO as the collector in high Ca2+ flotation wastewater. It is feasible and effective to replace high-cost wastewater treatment for molybdenum plants

A Novel Method for Improving Low-Temperature Flotation Performance of Nonpolar Oil in the Molybdenite Flotation

Nonpolar hydrocarbon oil (NHO) is one of the most extensively used collectors in the flotation of molybdenite due to its excellent selectivity. However, NHO has low sensibility at pulp temperature. At low temperatures (&lt;283 K), although more kerosene is used, the recovery of molybdenite flotation is still lower than at room temperature. In this study, magnetizing treatment, which is an efficient, low-cost, innovative, and environmentally friendly emulsification method, was used to improve the flotation performance of NHO in low-temperature molybdenite flotation. The test results showed that, compared with unmagnetized kerosene (UMK), the optimum dosage of magnetized kerosene (MK) could be reduced by 11% at 298 K. At the same dosage of kerosene, the flotation recovery of MK was 3% higher than UMK at 278 K. The surface tension measurement results showed that the surface tension of MK rose periodically as the magnetic field intensity increased, and there was a maximum surface tension within each period. Further, the magnetic field intensity had the maximum flotation recovery of molybdenite at the maximum surface tension of MK. Combined with the analysis based on the Girifalco&ndash;Good theory and the static drop volume method of interfacial tension, the interfacial tension of kerosene&ndash;water was shown to decrease with the increase of the surface tension of kerosene. This finding indicates that the dispersibility of kerosene in pulp could be improved by reducing the size of oil droplets, thereby improving the molybdenite flotation recovery of kerosene at low-temperature pulp. It is helpful to improve the flotation recovery of molybdenite using NHO as a collector for low-temperature pulp (&lt;283 K)

Effect of silica fume on shrinkage of cement-based materials mixed with alkali accelerator and alkali-free accelerator

The current price of silica fume has a more significant advantage than cement. Application in shotcrete can improve early strength and the durability of shotcrete, and has a good synergistic effect with accelerators to promote setting and hardening. This paper mainly studies the impact of silica fume (FS) on the shrinkage of cement-based materials mixed with the alkali accelerator and alkali-free accelerator. Test autogenous shrinkage, drying shrinkage, mass loss, and internal humidity change, and analyze with XRD, MIP, SEM and other test methods. At the age of 180 days, the autogenous shrinkage of 9FSAR-4 increased by 29.1% and the drying shrinkage increased by 33.5%, and the autogenous shrinkage of 9FSAS-7 increased by 23.1%, and the drying shrinkage increased by 33.8% compared with the blank group. The results show that: FS can significantly increase the autogenous shrinkage and drying shrinkage of cement mortar mixed with alkali accelerator and alkali-free accelerator. MIP tests found that the incorporation of FS could refine the pore structure of the cement paste, increasing the number of 5–50 nm pore sizes, which would increase the capillary tensile stress in the cement paste. Nevertheless, the addition of silica fume reduces the total porosity and makes the pore distribution shift towards the decreasing direction. It reduces the mass loss and internal humidity change of cement mortar under dry conditions. XRD test found that FS can significantly reduce the content of CH in cement paste, weakening the confinement effect of CH on C–S–H and C-A-H

The interaction between Ca2+ and molybdenite edges and its effect on molybdenum flotation

In this paper, the influence of Ca on the flotation of a skarn type molybdenum ore and pure molybdenite mineral at pH 8 was studied using diesel as the collector. It was found that Ca had little effect on molybdenum flotation at low concentrations. By further increasing Ca concentration, the floatability of molybdenite—especially from the fine size fractions—was depressed even without the presence of fine gangue minerals. The mechanism responsible for the deleterious effect of Ca on molybdenite flotation was studied by a range of techniques including zeta potential measurements, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectrometer (SEM-EDS) analyses and molybdenum phase analyses. It was found that Ca interacted with molybdenite edges producing CaMoO precipitates which were responsible for the depression of molybdenite flotation of Ca by preventing the adsorption of diesel