Scanning Electron Microscope-energy Dispersive Spectrometer Research Articles

Plant growth promoting bacteria and citric acid promote growth and cadmium phytoremediation in ryegrass

Based on the growth-promoting effect of plant growth promoting bacteria on plants and the mobilization of Cd by citric acid, an experiment was designed in which the combined treatment of Bacillus megaterium and citric acid promoted ryegrass to repair Cd-contaminated soil. This study aimed to evaluate the effects of different treatments on the antioxidant enzyme activity, photosynthesis intensity, Cd accumulation, and rhizosphere cadmium migration under cadmium contamination conditions. And the soil morphology and structure changes were studied by infrared spectroscopy FourierTransformInfrared(FT-IR) and scanning electron microscope Energy Dispersive Spectrometer(SEM-EDS) before and after different treatments. The results show that the combined treatment of Bacillus megaterium and citric acid significantly improved the oxidative stress defense and plant photosynthesis and increased of rye biomass. rye biomass 1.28 times higher than CK treatment. Joint treatment significantly increased the amount of shoot accumulation of Cd, 2.31 times higher than CK treatment, increased the migration and accumulation of cadmium. FTIR and SEM-EDS also showed that the organic constituents such as O-H, C-O and C-N in soils as a major mechanism for mobilization of the heavy metal Cd. Thus, the combined treatment of Bacillus megaterium and citric acid can promote plant growth, improve the damage to ryegrass caused by single organic acid addition, and improve the plant extraction efficiency, which is a feasible way to repair Cd-contaminated soil through activated extraction system.

A real-time monitoring of pre-overcharge in high‑nickel lithium ion batteries via plasma emission spectroscopy

Using the calibration-free atomic spectroscopic technique on lithium (Li) I with its wavelengths at 610.35, 610.65, and 670.79 nm, Li ion signals at varying state of charge (SOC) from high‑nickel (>88 %) batteries with NCA (Ni-Co-Al) cathode and SCN (silicon carbon nanocomposite) anode are detected in real-time (<3 s). The laser-induced plasma spectroscopy (LIPS) revealed that moderate changes in the concentrations of Li and metals (Ni, Co, and Al) during the normal charging underwent an abrupt concentration change in Li as the SOC reached above 75 %. Verified by using SEM-EDS (Scanning Electron Microscopy-Energy Dispersive Spectrometer), this sudden decrease of Li ions in cathode is deemed as being indicative of the state of overcharge. The present work is aimed at developing a new opto-chemical SOC sensor while the experimental set up offers a new method for detecting the state of pre-overcharge in nickel-rich Li-ion batteries.

Opto-electronic and electrochemical evaluations of particulate wo3 and sno2 in electrocodeposited Zn- tio2 nanocomposites coatings for sensor application

This study synthesized, characterized and determined the electronic and optical properties of Zn-TiO2, Zn-TiO2-WO3 and Zn-TiO2-SnO2 nano-composite coatings on low carbon steel. It has also determined the effect of these coatings on the corrosion of mild steel in saline environment. This was with a view to produce an active coating to providing alternative to hazardous chromium coating. Active multi functional nano crystalline coatings of the composites were electrolytically fabricated on low carbon steel from Zinc bath, with its Cation and nanoparticulates of TiO2, SnO2 and WO3 were uniformly codeposited in the Zn matrix. The nano-powders were characterized with Scanning Electron Microscope/Energy Dispersive Spectrometer (SEM/EDS) analyses for confirmation of the chemical compositions and purity. The electrocodeposition bath compositions were developed with 120 gram per litre of ZnCl2, 30 gram per litre of KCl along sides with the nanopowders. Other additives including cetylpridinum chloride, 2- Butyne 1,4diol were added as surfactants and Thiourea was added as stabilizer. The coated specimens were sectioned into parts, some of which were characterized with electrical meters and solar simulator to determine the electrical conductivity and solar response of the coated samples respectively. Samples were also subjected to corrosion experiment in 3.5% NaCl (saline) media to study their corrosion resistance properties in the test media through Potentiodynamic polarization method. The results, the electrical conductivity of the generated nano-composite coatings displayed a better electrical conductivity of 2.45E-01Ω-1m-1 which made it a better sensor material and outstanding corrosion resistance with corrosion rate at 0.10116 mm/year. The study concluded that both matrices with the Nano Particulate WO3 and SnO2 can be use as sensor materials but the WO3 matrix showed a better electrical conductivity both in the presence and absence of uv light and enhanced corrosion protection under light and dark conditions, thus a better sensor’s material.

Microstructural evolution and coarsening behavior of the precipitates in 2205 duplex stainless steel aged at 850 °C

The formation of the secondary phases in the 2205 duplex stainless steel (DSS) influences greatly its mechanical properties. Studies on the microstructural evolution and coarsening behavior of the precipitates in the 2205 DSS have both scientific and technological significance. In the present work, the evolution of the composition and morphology of the precipitates in the 2205 DSS aged at 850 °C for periods up to 200 h are systematically investigated by SEM/EDS (Scanning Electron Microscope/Energy Dispersive Spectrometer) and TEM (Transmission Electron Microscope). In addition, the size statistics for intermetallic precipitates, especially for the σ phase, are carried out based on the SEM images by using deep learning and digital image processing technique. Based on the above, the average interphase energy between the σ and γ phases is reasonably estimated according to the Ostwald coarsening mechanism. This work provides a comprehensive understanding of the microstructural evolution and coarsening behavior of the precipitates in 2205 DSS.

Towards an efficient p-n heterojunction in ternary composite material based polypyrrole, metal oxide and surface functionalized graphene for thermoelectric properties enhancement

The thermoelectric properties of ternary p-n heterojunction composites based on [p-type polymer/surface treated graphene/metal oxide in ceramic form] were investigated in this study. In the presence of ceramic tungsten oxide (WO3) particles and diazonium salt surface treated graphene, a simple in-situ pyrrole polymerization method was carried out. FTIR, Raman scattering, X-ray diffraction analysis (XRD), diffuse reflectance UV-Vis spectroscopy, I-V characteristics, and scanning electron microscopy - energy dispersive spectrometer (SEM-EDS) have all been used to characterize composites. Based on the comparison of observed thermoelectric parameters, the ternary composite created by PPy-FrGO (DS-SO3H)-WO3 based on functionalized graphene with diazonium salt (DS-SO3H) was chosen as having superior thermoelectric capabilities than the other samples. This advancement was made possible by combining two strategies: graphene functionalization with a conjugated diazonium salt and thermochemical treatment of tungsten oxide with the sol-gel method and sintering procedure. Functionalization reduced thermal conductivity (= 0.127 W.m−1. K−1) while adding ceramic tungsten oxide boosted electrical conductivity ( = 1087 S/m), resulting in a merit coefficient (ZT) of 1.63 × 10−4.

Effect of alternative silicon sources on alkali-activated carbon steel slag binder and silicon sources substitution mechanism

The high cost and carbon footprint of conventional alkali activator (sodium silicate) limit the wide-scale adaptation of alkali-activated materials. During the production of sodium silicate(SS), carbonate and silicate need to be calcined at 1400 °C, which is not environmentally friendly. In order to improve the sustainability of the activator, 10% SS was reduced in this paper. The effect alternative silicon sources (ASS) on the mechanical properties of alkali-activated carbon steel slag (CSS) prepared at room temperature were studied when the modulus is 0.5 and 1.0, and the mechanism of silicon source substitution was discussed by means of microscopic characterization. The substitution amount of ASS was 10% of the total CSS amount. ASS included waste glass powder (WGP), rice husk ash (RHA), diatomaceous earth (DE), diatomaceous earth analytical reagent (DEAR), and silica fume (SF). Microscopic characterization methods included X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential thermogravimetry (TG-DTG), and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The results show that the effect of ASS depended on the structure of SiQn, and is affected by the initial modulus of the activator. The compressive strengths of the low modulus samples are lower than that of the high modulus samples, while the effect of silicon source substitution is the opposite. However, the effect of SF is less affected by the initial modulus, and the 90d compressive strength of low modulus and high modulus differed by only 8%. 10% SF substitution can save at least 48.28% of industrial SS. SF is an economic and effective ASS, which can provide a better ecological choice for the production of alkali-activated CSS cementitious materials.

Efficacy and mechanisms of δ-MnO2 modified biochar with enhanced porous structure for uranium(VI) separation from wastewater

Even though uranium (U) is considered to be an essential strategic resource with vital significance to nuclear power development and climate change mitigation, U exposure to human and ecological environment has received growing concerns due to its both highly chemically toxic and radioactively hazardous property. In this study, a composite (M-BC) based on Ficus macrocarpa (banyan tree) aerial roots biochar (BC) modified by δ-MnO2 was designed to separate U(VI) from synthetic wastewater. The results showed that the separation capacity of M-BC was 61.53 mg/g under the solid – liquid ratio of 1 g/L, which was significantly higher than that of BC (12.39 mg/g). The separation behavior of U(VI) both by BC and M-BC fitted well with Freundlich isothermal models, indicating multilayer adsorption occurring on heterogeneous surfaces. The reaction process was consistent with the pseudo-second-order kinetic model and the main rate-limiting step was particle diffusion process. It is worthy to note that the removal of U(VI) by M-BC was maintained at 94.56% even after five cycles, indicating excellent reusability and promising application potential. Multiple characterization techniques (e.g. Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) and X-ray Photoelectron Spectroscopy (XPS)) uncovered that U(VI) complexation with oxygen-containing functional groups (e.g. O–CO and Mn–O) and cation exchange with protonated ≡MnOH were the dominant mechanisms for U(VI) removal. Application in real uranium wastewater treatment showed that 96% removal of U was achieved by M-BC and more than 92% of co-existing (potentially) toxic metals such as Tl, Co, Pb, Cu and Zn were simultaneously removed. The work verified a feasible candidate of banyan tree aerial roots biowaste based δ-MnO2-modified porous BC composites for efficient separation of U(VI) from uranium wastewater, which are beneficial to help address the dilemma between sustainability of nuclear power and subsequent hazard elimination.

An Archaeometallurgical Study of Medieval Knives from Kinet Höyük, Turkey

This paper examines the knives of the medieval period (13th -14th century AD) from Kinet Höyük in Cilicia, one of the most important areas of Anatolia for the history of iron production. The materials and production processes of 12 knives were revealed using archaeometry methods, such as Optical Microscopy (OM), Scanning Electron Microscope-Energy Dispersive X-Ray Spectrometer (SEM-EDS) analyses, and micro-hardness tests. An examination of the relationship between the shape and size of these knives was undertaken, along with a discussion of the factors involved in the manufacturing techniques. Among the medieval knives from Kinet Höyük that were analyzed, the results of the study indicate that besides blades made entirely of steel or wrought iron there are examples of forge-welding steel to wrought iron in a variety of ways. The largest group of knives is composed of small blades made only of steel. A particular example of this group is a blade made of crucible steel, which was skillfully forged and heat-treated. The medieval blades from Kinet Höyük exhibit a direct relationship between their shapes and their dimensional proportions. A specific production method, however, seems not to have been chosen in accordance with a given shape. The dimensions of the knives were more significant, particularly when only steel or only wrought iron was used. Based on the historical iron-producing activities in the region and the traces of intense blacksmithing practices found in the medieval layers of Kinet Höyük, it is argued that these knives are remnants of a skilled metal production culture.

Calcium alginate-nZVI-biochar for removal of Pb/Zn/Cd in water: Insights into governing mechanisms and performance

Heavy metals pollution in water caused by the intensification of industrial processes and human activities has attracted worldwide attention. Finding an environmental-friendly and efficient remediation method is in need. In this study, the calcium alginate entrapment and liquid-phase reduction method were used to prepare calcium alginate-nZVI-biochar composite (CANRC), which was firstly used to remove Pb2+, Zn2+, and Cd2+ in water. The effects of pyrolysis temperature, solution pH, and coexisting ions, etc. during adsorption processes were explored. Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the physicochemical properties of CANRC before and after adsorption. Different adsorption models and site energy analysis were used to analyze the possible mechanisms. The results showed that CANRC prepared at 300 °C and a 5 wt% Fe loading ratio had the maximum adsorption capacities with a dosage of 2.5 g/L and pH = 5.0– 6.0. The adsorption process was more in line with the Langmuir isotherm model dominated by monolayer adsorption. The maximum adsorption capacities of Pb2+, Zn2+, and Cd2+ were 247.99, 71.77, and 47.27 mg/g, respectively. Site energy analysis combined with XRD and XPS analysis indicated that surface complexation and precipitation were the main adsorption mechanisms. This study provides an alternative way for the removal of heavy metals from water.

Carbonate of strontium anchored at the edge of graphite

With the continuous growth of the fourth-generation nuclear reactor, the oxidation of irradiated graphite (i-graphite) has become a great concern worldwide in recent years, not only for the far-reaching significance in the treatment of i-graphite waste, but also for the safety evaluation of the reactor. Fission products (FPs) and activation of impurities are generated in i-graphite during reactor operation and inevitably released as radioactive dust when i-graphite is oxidized. The investigation of the binding mechanism between nuclides and graphite dust is vital for further separating procedures of off-gas decontamination. Herein, the mechanism of FP release during the oxidation of High-Temperature Gas-Cooled Reactors’ matrix graphite was explored with Strontium (Sr) as an example. The Sr-loaded matrix graphite was prepared by impregnation and characterized by secondary ion mass spectrometry (SIMS), X-ray powder diffraction (XRD), scanning electron microscope-energy dispersive spectrometer (SEM-EDS), and Raman spectra. The released Sr chemical speciation was extrapolated as SrCO3 through the investigation of the temperature and air flow rate effects on oxidation products. Additionally, the main morphology of the released fragment was identified as SrCO3 clusters anchored at the edge of graphite. The ab initio calculations revealed the mechanism for the anchoring of SrCO3 at the edge of graphite via adsorption. These findings provide a novel understanding of Sr-releasing behavior when i-graphite is oxidized.

Effects of clay minerals and organic matter on pore evolution of the early mature lacustrine shale in the Ordos Basin, China

Pores related to organic matter and clay minerals provide significant storage space for hydrocarbons in organic-rich shales. However, the pore structure evolution and its related influencing factors at the early oil window stage are unclear. This study attempts to reveal the controls of organic matter and clay minerals on the pore structure of the lacustrine organic-rich Chang 7 Shale by using thin-section observational, organic petrological, elemental, scanning electron microscopy/Energy Dispersive Spectrometer (SEM/EDS) analyses, and mineralogical analyses combined with the pore structure characterization of gas adsorption and mercury injection capillary pressure (MICP). The results show that micropores (<2nm) and mesopores (2-50 nm) contribute to the main storage space in organic-rich intervals of the Chang 7 Shale. Organic matter content controls the development of micro-pores while no effects on porosity in the early mature lacustrine shale. Shrinkage OM pores related to the expulsion of hydrocarbons are better developed than the complex pores and sponge pores. Total clay content is correlated with mesopores volume in organic-rich lacustrine shale. Multiple stepwise linear regression model between mesopores volume and different clay minerals shows that the pores with diameters in the ranges of 2-5 nm are controlled by illite, chlorite, and kaolinite, and the pores with diameters in the ranges of 5-10 nm and 10-20 nm are controlled by illite, while 20-50 nm pores rely on illite/smectite mixed layer (I/S) and illite. Thermal maturity shows a positive effect on pore volume and porosity. There are three types of transformations of clay minerals in lacustrine shale, including the smectite-illite conversion, smectite-illite-chlorite conversion, and anorthite/albite-to-kaolinite/illite conversion. These clay mineral conversions all show positive effects on pore volume, especially the anorthite/albite-to-kaolinite/illite conversion, while the smectite-illite conversion shows some negative effects on the connectivity of the pore system. Additionally, the control of macropore volume, porosity, and pore throat radius by chlorite cannot be ignored. The findings from this study contribute to a clear insight into the pore structure evolution of lacustrine shale.

Fate of Copper in Saline–Alkali Soil with Long-Term Application of Biogas Residue

The retention of copper (Cu) in saline–alkali soil (SAS) during long-term application of biogas residue (BR) with a high concentration of Cu raises concerns. In this work, the fate of Cu was detected using adsorption isotherms, scanning electron microscope—energy dispersive spectrometer, Fourier transform infrared spectrometer, X-ray diffraction, isothermal titration calorimetry, X-ray photoelectron spectroscopy, and microzone X-ray fluorescence spectrometer. The results showed that the main groups for Cu adsorption by SAS and BR were carboxyl, hydroxyl, amide and amine. The adsorption of Cu by the carboxyl group was entropy–enthalpy co-driven (|ΔH| &lt; |TΔS|, ΔH &lt; 0). The adsorption of Cu by the amine group was entropy-driven (|ΔH| &gt; |TΔS|, ΔH &gt; 0). The adsorption of Cu on the SAS and BR was achieved by organic matter rather than minerals. The degradation of BR in the SAS increases the content of Cu adsorption groups such as carboxyl and amine groups, and Cu was adsorbed on the surface or inside SAS through organic groups. This study provides further theoretical support for the application of BR in SAS.

An approach of cobalt recovery from waste copper converter slags using pig iron as capturing agent and simultaneous recovery of copper and tin

Massive amounts of waste copper converter slags have been produced from pyrometallurgical extraction of copper from copper concentrates, and the disposal of them in landfills creates serious environmental problems. However, this converter slag contains numerous valuable heavy metals, including copper, cobalt and tin etc. In this research, due to similar properties of iron and cobalt, pig iron with a low melting point was creatively used as capturing agent for cobalt recycling in a smelting reduction. The recovery of copper and tin was also studied. The phase transformation during reduction process was clarified by X-ray diffraction and Scanning electron microscope-energy dispersive spectrometer analyses. After the reduction performed at 1250 °C, the copper, cobalt and tin were recovered in a copper-cobalt-tin-iron alloy. The addition of pig iron improved cobalt yield, which was ascribed to the enrichment of cobalt in an iron–cobalt alloy phase. This decreased activity of the reduced cobalt and promoted reduction of cobalt oxide. As a result, the cobalt yield had a significant increase from 66.2% to 90.1% by adding 2% pig iron. Similarly, the copper also accelerated tin recovery through the formation of a copper–tin alloy. The copper and tin yields reached 94.4% and 95.0%, respectively. This work provided a high efficiency method to recover copper, cobalt and tin from waste copper converter slags.

Polyphenols Can Improve Resin-Dentin Bond Durability by Promoting Amorphous Calcium Phosphate Nanoparticles to Backfill the Dentin Matrix.

To investigate the effects of proanthocyanidins (PA), myricetin, resveratrol, and kaempferol on the modification of dentin collagen and the inhibition of matrix metalloproteinase (MMP) activity, and to evaluate their contributions to the biomimetic remineralization and resin-dentin bonding performance. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and in situ zymography were applied to verify the collagen modification and MMP activity inhibition induced by these four polyphenols. Scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) analysis, X-ray diffraction (XRD), ATR-FTIR, Vickers hardness numbers (VHN), and micro-computed tomography (micro-CT) were performed to characterize the remineralized dentin. Microtensile bond strength (μTBS) and nanoleakage were investigated to evaluate the effects of the four polyphenols on resin-dentin bonding durability. ATR-FTIR and in situ zymography confirmed that these four polyphenols could modify dentin collagen and inhibit MMP activity, respectively. Chemoanalytic characterization exhibited the efficacies of the four polyphenols in promoting dentin biomimetic remineralization. The surface hardness of PA-pretreated dentin was the greatest. Micro-CT results demonstrated that the PAs group possessed the highest amount of dentin surface minerals and the lowest amount of deep-layer minerals. The surface and deep-layer mineral contents of the Myr group were higher than Res and Kae groups. Treatment with these four polyphenols significantly increased the initial μTBS compared with the control group without primer conditioning. μTBS decreased significantly during aging, and the decrease was more severe in the PAs and Kae groups than in the Myr and Res groups. With or without aging, the polyphenol groups exhibited relatively less fluorescence. However, the Myr and Res groups showed less serious nanoleakage after aging. PA, myricetin, resveratrol, and kaempferol can modify dentin collagen, inhibit MMP activity, promote biomimetic remineralization, and improve resin-dentin bond durability. Compared with PA and kaempferol, myricetin and resveratrol are more effective in improving resin-dentin bonding.

Performance and Microstructure Characterizations of Halloysite Nanotubes Composite Flame Retardant–Modified Asphalt

To solve the problems of low flame retardant efficiency and weak low-temperature performance of asphalt modified by conventional flame retardants (CFR), in this study, halloysite nanotubes (HNTs) and CFR were used to prepare nanocomposite flame retardants (NCFR) to modify asphalt. A fluorescence microscope (FM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) were used to characterize the microstructure of NCFR-modified asphalt. An oxygen index meter, Cleveland open cup, and cone calorimeter were used to test the flame retardant properties of the asphalt. A dynamic shear rheometer, bending beam rheometer, and force ductility tester were used to test the rheological properties of asphalt. At the same time, flame retardant–modified asphalt mixtures were prepared to verify the flame retardancy and road performance of the flame retardant–modified asphalt. The research results showed that the asphalt modified with 8% CFR and 1% HNTs (MA/CFR/1% HNTs) showed better dispersibility. The increase of limiting oxygen index and self-ignition temperature and the decrease of heat release rate and smoke production rate of MA/CFR/1% HNTs indicated that it has good flame retardancy. At 64°C, compared with modified asphalt (MA), the rutting factor of MA/CFR/1% HNTs increased by 88.17%, the creep recovery increased, and the irreversible creep decreased, indicating that its high-temperature performance improved significantly. At −18°C, compared with that of MA/CFR, the low-temperature creep stiffness of MA/CFR/1% HNTs decreased by 36 MPa and the creep rate of MA/CFR/1% HNTs increased by 0.034, indicating that only 1% HNTs can improve the effect of degraded CFR on the low-temperature performance of MA. Simultaneously, MA/CFR and MA/CFR/1% HNTs can improve the high-temperature performance and water stability of asphalt mixtures. Adding 1% HNTs to a MA/CFR-modified asphalt mixture can improve the low-temperature performance of the asphalt mixture to the level of the low-temperature performance of the modified asphalt mixture. In summary, the modification of asphalt with 1% HNTs and 8% CFR can effectively improve the flame retardant efficiency and significantly improve the road performance of asphalt.

Solidification/stabilization treatment of Hong Kong marine deposits slurry at high water content by ISSA and GGBS

Soft soils have been adopted as a conventional fill material in land reclamation projects, which is quite promising in Hong Kong with a huge mass of dredged marine sediments produced per year. It is proposed to use Hong Kong marine deposits (HKMD) as fill material treated by stabilisation/solidification (S/S) technology with sustainable binding material. In this work, lime, incinerated sewage sludge ash (ISSA) and ground granulated blast furnace slag (GGBS) were selected as the binding materials. The S/S performance of the binders on HKMD slurry was investigated. The results showed that the use of ISSA and GGBS as part of the binder is effective in promoting the strength of HKMD slurry with a high initial water content of 200%. The HKMD slurry treated by 30% binders (30% lime and 70% (ISSA + GGBS) with ISSA: GGBS = 3) gains strength, which became higher with increasing curing time. The results from X-ray diffraction (XRD), thermo-gravimetric (TG) analysis and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) presented the formations of calcium (aluminium) silicate hydrate (C-(A)-S-H), Friedel’s salt, and ettringite, which are mainly responsible for the strength increase of treated HKMD with their phases filling into the pores, interlocking and reinforcing the particles in the mixture. The porosity of the treated HKMD in bulk and powder state was determined by mercury intrusion porosimetry technique (MIP) and nitrogen adsorption/desorption isotherms (NAI), it is found that the bulk porosity of treated HKMD samples reduces with curing time due to the neoformations, especially the ettringite crystal by SEM results. This work indicates the potential application of lime-activated recycling wastes (i.e., ISSA and GGBS) for S/S treatment of HKMD slurry.

Modification of Rare Earth Ce on Inclusions in W350 Non-Oriented Silicon Steel

In this paper, the effect of rare earth Ce content on the morphology, composition, type and size distribution of inclusions in W350 non-oriented silicon steel was investigated by means of ICP-MS (inductively coupled plasma mass spectrometry), SEM/EDS (scanning electron microscope-energy Dispersive Spectrometer), and ASPEX (automated SEM/EDS inclusion analysis). The results showed that with the increase of Ce content in the steel, the modification sequence of inclusions was CeAlO3→Ce2O2S→CexSy. The type and size distribution of inclusions in the steel obviously changed with the difference in added Ce content. When the added Ce content in the steel was 10 ppm, 14 ppm, 20 ppm and 30 ppm respectively, the rare earth inclusions were mainly CeAlO3-Ce2O2S. Furthermore, when the added Ce content increased to 60 ppm, the rare earth inclusions were mainly Ce2O2S with a small amount of CeAlO3 contained in part inclusions. When the added Ce content increased continually to 95 ppm, the rare earth inclusions were mainly CexSy-Ce2O2S. The critical Ce content for the conversion between CeAlO3 and Ce2O2S was 41 ppm. To ensure that inclusions transform from CeAlO3 to Ce2O2S, the Ce content in the steel should be greater than 41 ppm. Under the current experimental conditions, it was found that when the Ce content was 20 ppm, the number density and proportion of inclusions in the steel were lower, and their average size was larger. When the added Ce content increased to 95 ppm, the number density of inclusions in the steel significantly increased, which deteriorated the steel cleanliness.

Removal of residual benzohydroxamic acid-lead complex from mineral processing wastewater by metal ion combined with gangue minerals

Benzohydroxamic acid-lead (BHA-Pb) complex reagent is a commonly used collector for the flotation of oxidized ores such as tungsten ore, cassiterite, and ilmenite, but the BHA-Pb complex remaining in the mineral processing wastewater (MPW) after flotation is economically and efficiently difficult to remove. At present, the treatment technology usually starts from the treatment of MPW at a wastewater treatment station. However, the treatment cost is inevitably high due to the huge amount of MPW. In this study, a new process of removing residual BHA-Pb complex reagent from MPW in one-step using metal ions combined with gangue minerals in tailings pulp was proposed. It started from tailings pulp treatment and taking tailings reservoir as the main reaction site. The basic issues related to the new process were mainly studied. The concentration of BHA was characterized using chemical oxygen demand (COD). The results show that when Ca2+, Fe3+, or Al3+ was added to the BHA-Pb solution, only Fe3+ could effectively remove the COD of the BHA-Pb solution, while Ca2+ and Al3+ could not. This is because the BHA-Pb complex can be preferentially transformed into the BHA-Fe complex, and the COD of the BHA-Fe complex solution is most easily removed. However, BHA-Fe complex systems have dark colors and are difficult to settle. When gangue minerals are added to the BHA-Fe complex system, gangue minerals can play the role of coarse particles carrying fine particles settling, which is helpful to the sedimentation of the BHA-Fe complex system. The transformation mechanism between BHA-Pb and BHA-Fe complexes was explained by the conditional stability constants and Gibbs free energy changes analysis. In addition, the sedimentation mechanism of the BHA-Fe complex system was analyzed by zeta potential and scanning electron microscope-energy dispersive spectrometer. This study provides a new idea for removing residual organic flotation reagents from MPW starting from tailings pulp treatment.

Arsenic removal from acidic industrial wastewater by ultrasonic activated phosphorus pentasulfide

Arsenic is one of the main harmful elements in industrial wastewater. How to remove arsenic has always been one of the research hotspots in academic circles. In the process of arsenic removal by traditional sulfuration, the use of traditional sulfurizing agent will introduce new metal cations, which will affect the recycling of acid. In this study, phosphorus pentasulfide (P2S5) was used as sulfurizing agent, which hydrolyzed to produce H3PO4 and H2S without introducing new metal cations. The effect of ultrasound on arsenic removal by P2S5 was studied. Under the action of ultrasound, the utilization of P2S5 was improved and the reaction time was shortened. The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions. Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5% could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min. In the first 60 min, under the same S/As molar ratio and reaction time, the ultrasonic hydrolysis efficiency of P2S5 was higher. This is because P2S5 forms ([(P2S4)])2+ under the ultrasonic action, and the structure is damaged, which is easier to be hydrolyzed. In addition, the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy. Our research avoids the introduction of metal cations in the arsenic removal process, and shortens the reaction time.

Modified β-cyclodextrin microspheres towards the application in intumescent fire resistance and smoke-suppressing of bio-based poly(L-lactic acid)

In this work, the β-cyclodextrin (β-CD) was modified by a phosphazene compound to prepare a novel amorphous derivate (β-CDCP), which was combined with the ammonium polyphosphate (APP) as a synergistic flame retardant (FR) of the bio-based poly(L-lactic acid) (PLA). The effects of the APP/β-CDCP on the thermal stability, combustion behavior, pyrolysis process, fire resistance performance and crystallizability of the PLA were investigated comprehensively and in depth by thermogravimetric (TG) analysis, limited oxygen index (LOI) analysis, UL-94 test, cone calorimetry measurement, TG-infrared (TG-IR), scanning electron microscopy-energy dispersive spectrometer, Raman spectroscopy, pyrolysis-gas chromatography/mass spectrometry and differential scanning calorimetry. The PLA/5%APP/10%β-CDCP showed a highest LOI of 33.2 %, passed V-0 rating and exhibited self-extinguish phenomenon in the UL-94 test. Also, it presented a lowest peak of heat release rate, total heat release, peak of smoke production rate and total smoke release, and a highest char yield treated by cone calorimetry analysis. In addition, the 5%APP/10%β-CDCP shortened significantly crystallization time and enhanced crystallization rate of the PLA. Gas phase and intumescent condensed phase fire proofing mechanisms are proposed to elucidate enhanced fire resistance in this system in detail.