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Developing highly efficient calcined diatomite (C-D)-based filter aids with excellent adsorption performance is of great significance. Herein, Zeolite-P was successfully synthesized on the surface of C-D through hydrothermal modification with NaOH and MgCl2 as efficient morphology control agents. The optimal Zeolite-P/C-D material perfectly retained the diatomite structure and showed a whiteness of 83.36% and a high specific surface area of 237.47 m2/g, leading to an excellent adsorption capacity for methylene blue trihydrate (MB) of 125.46 mg/g and a good permeability of 0.43 darcy. The porous fibrous microspheres Zeolite-P was synthesized on the surface of C-D under controlled conditions to improve the adsorption performance of Zeolite-P/C-D material. By developing diatomite-based composites for filter aids applications, this study paves the way for the comprehensive and efficient utilization of low-cost diatomite resources. [ABSTRACT FROM AUTHOR]

Surface heterogeneity of minerals can significantly affect the adsorption of collectors. Petroleum sulfonate is widely used as a fluorite collector, but how the surface heterogeneity of fluorite influences the adsorption of alkyl sulfonates remains unknown. Herein, two kinds of surface heterogeneity situations, i.e., edge and (1 1 1) _vacancy, were modeled, and the adsorption of sodium dodecyl sulfonate on them was simulated. The results show that the stable adsorption configuration of sodium dodecyl sulfonate on the edge was in a bridged mode, and the stable interaction configuration with vacancy was in a tridentate mode. The 2p orbit of fluorine on the surface of the edge and the vacancy could hinder collector adsorption. After adsorption, the 3d orbit of calcium interacted with the collector orbit above Fermi level, and moved towards the lower energy level, benefiting the adsorption process. It was also found that the adsorption intensity/strength of alkyl sulfonate on fluorite was directly proportional to the interaction intensity of the collector with the 3d orbits of calcium ions on the surface and vacancy. Therefore, the rough fluorite surface had a stronger adsorption effect on the collector, and the existence of vacancy could improve the surface adsorption energy, and thus enhance the adsorption of the collector on the fluorite surface. The rough fluorite surface requires high collector concentration to achieve saturated monolayer adsorption, so increasing vacancy was the better choice to improve the adsorption capacity of alkyl sulfonate on the fluorite surface. This study provides novel insights into the flotation mechanism, in the context of surface heterogeneity, and could guide the design of high-performance collectors for fluorite ore flotation. [ABSTRACT FROM AUTHOR]

Quartz powder (QP) is an inorganic filler that is expected to significantly enhance the dielectric and mechanical properties of epoxy (EP)-based composites applied in copper clad laminates and epoxy molding compounds for 5G applications. As is well-known, the performance of the QP–EP composites is directly correlated with the dispersion effect and the compatibility of QP with an EP matrix. Herein, we propose the surface modification method of QP by mixing SCAs of different alkyl chain lengths that contain amino and carbonyl groups. Different characterization methods (FTIR, TGA, XPS, SEM, contact angle measurement, viscosity, and mechanical properties) and molecular dynamics simulation were adopted to study its effect and mechanism. Through dual SCA modification, the viscosity of QP–EP composites was reduced by 11.70%, and the flexural and tensile strengths increased by 16.89% and 30.01%, respectively. In addition, it was revealed that the superiority of dual SCAs originated from the synergistic effect between APTES and SPIS, it was the electrostatic repulsion force between the amino groups of the two SCAs that caused a steric hindrance that activated the steric stabilization effect of SPIS, thus resulting in better dispersion and excellent compatibility. Meanwhile, the amino and carbonyl groups of the SCA interacted with the EP matrix via chemical bonds and hydrogen bonds, thus strengthening the interfacial adhesion between the QP and EP matrix and improving the mechanical performance of QP–EP composites. These results are evidence of the potential of the proposed approach, which is based on the synergistic compounding of SCA with different molecular structures, in powder industrial applications. [ABSTRACT FROM AUTHOR]

Na3V2O2(PO4)2F (NVOPF) as an attractive electrode material has received much attention based on the one‐electron reaction of V4+/V5+. However, the electrochemical reactions involving lower vanadium valences were not investigated till now. Herein, a composite of graphene decorated nanosheet‐assembled NVOPF microflowers (NVOPF/G) was synthesized and the multi‐electron reaction of NVOPF/G was conducted by controlling the operation voltage windows. The reaction mechanism, structural changes, and vanadium valences during the insertion/extraction of Li ions (from 2 to 6) were elucidated clearly by in‐situ X‐ray diffraction and ex‐situ X‐ray photoelectron spectroscopy. Theoretical computations also revealed the Li‐ion locations in the structure of NaV2O2(PO4)2F. Due to the additional redox couple of V3+/V4+, NVOPF/G displayed a much higher initial capacity of 183.3 mAh g−1 in the wider voltage window of 1.0–4.8 V than that of 2.5–4.8 V (129.3 mAh g−1). Moreover, excellent Li‐storage performance of NVOPF/G at a lower voltage (≤2.5 V) with the active reaction of V2+/V3+/V4+ was obtained for the first time, demonstrating the high potential of NVOPF/G as an anode material for Li ion storage. [ABSTRACT FROM AUTHOR]

Andalusite and kyanite are two polymorphic minerals with the same formula but different crystal structures. Despite of their high economic values, selectively recovering them by flotation is a challenge. The flotation recovery of andalusite is higher than that of kyanite with sodium oleate. Sodium oleate adsorbs onto the surfaces mainly through the chemical interaction of oleate ions with aluminum atoms. The higher adsorption of sodium oleate on andalusite surface between the two minerals is related to the higher chemical activity of the aluminum atoms which leads to the better affinity and therefore the lower adsorption energy of sodium oleate. [ABSTRACT FROM AUTHOR]

The surface properties of minerals are governed by the crystal chemistry of their cleaved and exposed surfaces, which will vary with the reduction of particle size under mechanical crushing or grinding. Molecular dynamics (MD) simulations were used to study the adsorption conformations and interaction energies of sodium oleate (NaOL) on different fluorite (CaF 2 ) surfaces in an explicit solution system. Three fluorite crystal planes, namely, the (1 1 1) surface, the (1 1 0) surface and the (3 1 1) surface, were considered. Anisotropic surface energies and broken bond densities were calculated based on density function theory (DFT) to confirm the cleavage plane of fluorite and to investigate the crystal-chemical characteristics of fluorite crystal planes. It was demonstrated that NaOL preferentially combined in a bridged ring complex configuration with the most stable plane of fluorite, the (1 1 1) surface, which bears a Ca┄F broken bond density of 100%. The exposure of the (1 1 0) surface of fluorite limited its flotation response to NaOL collectors, as this surface exhibited a lower affinity for NaOL, agreeing well with the results of the fluorite flotation experiments performed with different size distributions. The anisotropy of fluorite with different size fractions was further verified by X-ray diffraction (XRD) analyses. The findings in this work suggest that the flotability of fluorite could be further improved if a selective grinding process is applied to favour the exposure of the (1 1 1) surface. [ABSTRACT FROM AUTHOR]

This investigation aims to demonstrate the effects of hydrophobic tails on the affinity and relevant flotation response of sulfonate-based collectors for fluorite. For this purpose, a series of alkyl sulfonates with different hydrophobic tails, namely sodium decanesulfonate (C10), sodium dodecylsulfate (C12), sodium hexadecanesulfonate (C16), and sodium dodecylbenzenesulfonate (C12B) were applied. The flotation tests showed that C12 and C12B had a better collecting performance than C10 and C16 at pH < 10, and the flotation recovery of fluorite was higher when adopting C12B as a collector compared with C12 with a strong base. The adsorption behaviors of collectors on the fluorite surface were studied through zeta potential, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. It was found that the affinity of alkyl sulfonates for fluorite was enhanced with the increase of the alkyl chain length from C10 to C16. The existence of phenyl in the hydrophobic tail of sulfonates could improve its activity for fluorite by reducing its surface tension. The abnormal phenomenon C16 with a high affinity for fluorite had a low collecting performance for fluorite mainly due to its overlong alkyl chain, resulting in low solubility in pulp, which restrained its interaction with fluorite. We concluded that C12B was the most applicable collector for fluorite among these reagents due to its high activity, high solubility, and low cost, which was further substantiated by calculating their molecular frontier orbital energy. [ABSTRACT FROM AUTHOR]

As secondary mineral resources, diatomite tailings (DT) got from the Linjiang region of China were prepared and characterized by SEM, XRF and XRD. Mono-factor experiments were carried out to investigate the effects of the operation factor, including contact time, adsorbent concentration, initial pH value of the dye solutions, adsorption temperature and initial concentration of cationic Red X-GRL (X-GRL) on the adsorption of X-GRL. The adsorption kinetics, isotherms, thermodynamics and mechanisms for X-GRL were also studied. It was efficient for DT to adsorb X-GRL from aqueous solutions, and it was even discovered to have higher adsorptivity for X-GRL than diatomite concentrate (DC) in our previous test. The adsorption processes fit very well with the pseudo-second-order model and the Langmuir isotherm equation. In addition, various thermodynamic parameters, such as standard Gibbs free energy ( ΔG°), standard enthalpy ( ΔH°) and standard entropy ( ΔS°) have been calculated. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic. The main driving forces of the physical adsorption on DT are electrostatic attraction. The reason why DT showed higher adsorptivity for X-GRL than DC was that there were more clay mineral particles within, which has a remarkable ability of dye adsorption due to its high surface area. DT as a cheap absorbent for X-GRL removal would replace or partially replace the activated carbon. [ABSTRACT FROM AUTHOR]

This paper, based on the literature review and field investigation, studied the status quo of maker spaces in main urban district of Chengdu at a time when the development of the maker spaces has received strong support from national and local governments. In addition to introducing the related concepts and policy support of the maker space, it summarized its distribution characteristics, audience characteristics and status quo as well as problems and presented the direction for the development of the maker space in main urban area of Chengdu grounded on a survey of the status quo of national maker spaces in main urban area of Chengdu. [ABSTRACT FROM AUTHOR]

• The effect of active substance content and molecular weight of petroleum sulfonate on fluorite flotation were studied. • The adsorption configuration and aggregation of petroleum sulfonate with different sulfonate degree were studied by molecular dynamics simulation. • The configuration change of di-sulfonate over concentration was explained by the adsorption energy per unit area and adsorption energy per bond. • Steric-hindrance is the main cause of flotation difference of alkyl sulfonate with different sulfonate degree at high concentration. Fluorite is an important non-metallic mineral, and the most efficient way to separate it from gangue is flotation. The commonly used collectors are oleic acid and oxidized paraffin soap, but those two collectors both have a problem of bad solubility, this phenomenon worsens at low temperature. Sodium petroleum sulfonate exhibits a good collecting performance on fluorite, but it has not been systematically studied. In this paper, different types of sodium petroleum sulfonate were used to evaluate the effect of active substance content and average molecular weight. Molecular dynamics simulation was used to understand the mechanism that causes the flotation difference between mono-sulfonate and di-sulfonate. This study identifies that active content has a positive effect on the flotation recovery of fluorite while the molecular weight plays a negative role. The reason why di-sulfonate's performance is relatively weak at high concentration lies on the steric-hindrance effect, larger cross-sectional area limits the tail–tail interaction between sulfonates. [ABSTRACT FROM AUTHOR]

• PESA was introduced as a potential depressant for calcite in smithsonite flotation. • The separation of smithsonite from calcite could be achieved using a reagent scheme of PESA/NaOl. • The pretreatment of PESA selectively inhibited the NaOl adsorption onto the calcite surface. • PESA interacted with the calcium species at the calcite surface by chemisorption. As a green organic acid with biodegradable and low-cost characters, polyepoxysuccinic acid (PESA) was utilized as a depressant to achieve the flotation separation of smithsonite from calcite in this study. Microflotation tests showed that both smithsonite and calcite had good floatability when using sodium oleate (NaOl) as the collector, while calcite was selectively depressed when using PESA as the depressant. The flotation of artificially mixed minerals confirmed that the efficient separation of smithsonite from calcite could be realized in the presence of PESA. A flotation concentrate with 44.56% Zn grade and 81.03% recovery could be obtained from the original feed (26.59% Zn grade) using the reagent scheme of PESA/NaOl. Zeta potential measurement indicated that the addition of PESA might prevent the NaOl adsorption onto a calcite surface rather than a smithsonite surface. X-ray photoelectron spectroscopy (XPS) analysis revealed the strong chemical bonding could only occur between the carboxyl group of PESA and calcium ions at the calcite surface. In contrast, weak interaction occurred between PESA and smithsonite surface, then NaOl was still easily absorbed onto smithsonite surface. These results demonstrated that PESA could be used as a selective depressant for calcite in the smithsonite flotation. [ABSTRACT FROM AUTHOR]

Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) as an attractive electrode material has received much attention based on the one-electron reaction of V 4+ /V 5+ . However, the electrochemical reactions involving lower vanadium valences were not investigated till now. Herein, a composite of graphene decorated nanosheet-assembled NVOPF microflowers (NVOPF/G) was synthesized and the multi-electron reaction of NVOPF/G was conducted by controlling the operation voltage windows. The reaction mechanism, structural changes, and vanadium valences during the insertion/extraction of Li ions (from 2 to 6) were elucidated clearly by in-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy. Theoretical computations also revealed the Li-ion locations in the structure of NaV 2 O 2 (PO 4 ) 2 F. Due to the additional redox couple of V 3+ /V 4+ , NVOPF/G displayed a much higher initial capacity of 183.3 mAh g -1 in the wider voltage window of 1.0-4.8 V than that of 2.5-4.8 V (129.3 mAh g -1 ). Moreover, excellent Li-storage performance of NVOPF/G at a lower voltage (≤2.5 V) with the active reaction of V 2+ /V 3+ /V 4+ was obtained for the first time, demonstrating the high potential of NVOPF/G as an anode material for Li ion storage., (© 2021 Wiley-VCH GmbH.)

The adsorption behavior of natural zeolite was studied in order to determine the adsorption capacity and mass-transfer process of cationic red X-GRL (C(18)H(21)BrN(6)) onto the adsorbent. The adsorption tests to determine both the uptake capacity and the mass-transfer process at equilibrium were performed under batch conditions, which showed rapid uptake in general for the initial 5 min, corresponding to 92% total removal. The equilibrium adsorption capacity value (q(e,cal)) in pseudo-second-order kinetics was 13.51 mg/g at 293 K and the whole adsorption process was governed by physical adsorption with an endothermic, endothermic spontaneous nature. Adsorption tests indicated that the zeolite has great potential as an alternative low-cost material in the treatment of X-GRL drainage. However, the mass-transfer process to determine the rate-controlling steps showed that both film diffusion and pore diffusion were important in controlling the adsorption rate. The adsorption process was governed by film diffusion while pore diffusion was poor because the X-GRL molecules could not penetrate into the zeolite easily. The X-GRL molecules were only adsorbed on the external surface of the zeolite. Hence, to improve the adsorption capacity of natural zeolite further, modification to expand its micropores is necessary.