Scanning Electron Microscope With Energy Dispersive Spectrometer Research Articles

Fate of fluorine in stratified samples from BGL gasifier at Hailar Chemical Plant, Inner Mongolia: An intermediate process perspective

This study investigated the fate of Fluorine (F) during the super high temperature (2000 °C) gasification process by analyzing 23 stratified samples inside the British Gas Lurgi (BGL) gasifier in production. Through sequential chemical extraction (SCEP), ion selective electrode (ISE), scanning electron microscope with energy dispersive spectrometer (SEM-EDS), high-resolution transmission electron microscope with energy dispersive spectrometer (HRTEM-EDS) and X-ray diffraction (XRD), this article complements the intermediate forms of transformation of F, in addition to the methods of deduction of the fate of F through input and output.Overall, the concentration of fluorine gradually decreases with increasing temperature and ≈1200 °C (14th layer) is the key temperature for its volatilisation. This may be related not only to the volatility of organic matter, but also to the significant contribution from the melting of a large amount of silicate and aluminosilicate minerals in the sample.In addition, the fluorine concentration remained stable from layer 14 to layer 27 (≈2000 °C), rather than continuing to evaporate, due to the formation of a new, stable mode of fluorine occurrence: Ca-P-F-Si minerals have been identified. The free and active SiO2, possibly derived from the melting of quartz and kaolinite, played a key role in preventing the melting of fluorapatite. The mechanism of formation of the new refractory materials (Ca-P-F-Si minerals) needs to be further validated by laboratory and computer simulations.

Simple method for quantification of metal-based particles in biopsy samples of patients with long bone implants – Pilot study

The presence of particles fixed in tissue samples due to implant degradation or disintegration plays an important role in post-operative complications. The ability to determine the size, shape, chemical composition and, above all, the number of these particles can be used in many areas of medicine. This study presents a novel, simple metal-based particle detection method using scanning electron microscopy with energy dispersive spectrometer (SEM-EDS). The presence of metal particles in biopsy specimens from long bone nail-fixated implants (10 patients with titanium steel nails and 10 patients with stainless steel nails) was studied. The samples were analysed using automated area analysis based on image binarization and brightness to 255 grayscale. The results were supplemented with histological data and statistically analysed. The method based on the software used was found to be accurate and easy to use and, thus, appears to be very suitable for particle detection in similar samples.

Removal of Pb(II) from Aqueous Solution and Adsorption Kinetics of Corn Stalk Biochar

In this work, the Pb adsorption and removal ability of biochar from simulated Pb(II)-contaminated wastewater, adsorption isotherms, kinetics, and thermodynamics were studied. Adsorption characteristics of biochar on Pb(II) were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). The influence of the pH of the solution, the contact time, and the biochar dose on the removal of Pb(II) were investigated by single-factor design and response surface analysis. With the increase in biochar dose from 2 g/L to 4 g/L in wastewater, the Pb(II) amount adsorbed on biochar reduced from 21.3 mg/g to 17.5 mg/g. A weakly acidic environment was more conducive to the ligand exchange between Pb(II) ions and biochar. Pb(II) adsorption kinetics of biochar showed that the Pseudo-first-order model was more suitable than other employed models to describe the adsorption process. During the isothermal adsorption process, Langmuir and Freundlich’s isotherms fitted the adsorption data very well (R2 > 96%). The Pb (II) adsorption onto biochar was spontaneous in the specified temperature range (298–318 K) and the process was exothermic. Simultaneously, the optimal conditions were a pH of 5, a contact time of 255 min, and a biochar dose of 3 g/L, under which the maximum predicted Pb(II) removal efficiency was 91.52%.

Features of accumulation of chemical elements in the volume of the lens in senile cataract

This study provides a detailed analysis of the bioinorganic chemical composition of lens substance in patients with senile cataract using classical and spatial statistics methods. The study included 30 isolated human lenses. The light scattering ability (LSA) of the lens substance was evaluated using an original method. Additionally, distribution of chemical elements in the lens substance was analyzed using a scanning electron microscope with energy dispersive spectrometer (SEM/EDS). Measurements by all methods were carried out in a single coordinate space, which made it possible to compare the spatial correlation of different parameters. Small-angle light scattering of the lens substance has been quantitatively characterized for the first time. In contrast to the conventional norm, in senile cataract the accumulation fields of the majority of ion-forming elements (including Na, P, K, Cl) are distributed along the lines repeating the geometry of the lens capsule. At the same time, the light scattering ability of certain areas of the lens is significantly correlated with changes in the concentrations of Na, P, K, Ca in these areas. In particular, one ion-forming element can be distinguished - Na: spatial change of its concentration in senile cataract is strongly associated with a local change in LSA of the lens with opacities clustering of any degree. Thus, a change in the nature of the Na accumulation in the lens volume can be considered the main marker of senile cataract formation. The distribution pattern of ion-forming elements indicates that the loss of barrier properties in the capsule plays a significant role in the development of senile cataract.

Investigation on solar light assisted degradation of perilous Chromotrope-FB and Ponceau-BS colorants by Ag-doped ZrFe2O4: a greener environmental remediation approach

ABSTRACT Silver-doped zirconium ferrite (AxZ1-xFO, x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1) nanoparticles (NPs) have been successfully synthesised by utilising the facile auto-combustion approach. The synthesis of NPs has been confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope with energy-dispersive spectrometer (SEM-EDS), high-resolution transmission electron microscope (HR-TEM) and Brunauer–Emmett–Teller (BET) analytical techniques. The magnetic and optical properties of synthesised AxZ1-xFO NPs have been investigated using a vibrating sample magnetometer (VSM) and UV-Visible spectroscopy, respectively. Additionally, herein the prepared magnetic NPs have been utilised for the photodegradation of hazardous colouring agents, namely, Chromotrope-FB (Chr-FB) and Ponceau-BS (PBS). The prepared NPs, particularly AxZ1-xFO, (x = 0.8), showed excellent photoresponse for photodegradation of Chr-FB and PBS having a % degradation of 99.77% for Chr-FB and 99.21% for PBS in just 40 and 45 min, respectively, under solar irradiation. The photocatalytic degradation has been determined by the electron-hole mechanism in which the electrons are transferred from the valence band to the conduction band of the photocatalyst’s surface and combined with oxygen or water to form radicals. It has been found that the radical played a significant role in the photodegradation of Chr-FB and PBSs in the presence of AxZ1-xFO, (x = 0.8). In addition, UV-Visible spectroscopy and mass spectrometry were used to analyse the degradation process. Moreover, the photocatalyst AxZ1-xFO (x = 0.8) achieved notable stability and reusability, thus making it an effective catalyst for environmental pollutant degradation.

Effects of phosphorous-based additive on flow properties of high silicon-aluminum coal ash

• Effects of Ca 3 (PO 4 ) 2 addition on the fluidity of Huainan coal ash were revealed. • Phosphorus decreased ash fusion temperatures and temperature of critical viscosity. • Phosphorus contributed to the formation of slag during the ash fusion process. • Polymerization of slag structure was enhanced by phosphorus at high temperatures. • Crystallization in the slag during cooling was restricted by phosphorus. Co-gasification with coal is a promising way to dispose the sewage sludge with high phosphorus content, but the lack of data on the flow properties of phosphorus-containing ashes and slags under reducing atmosphere limits the gasification of this fuel. In this study, Ca 3 (PO 4 ) 2 was chosen as the phosphorus model compound of sewage sludge and was added into one high-silicon-aluminum coal (Huainan, HN). Ash fusion temperatures (AFTs) and viscosity-temperature properties of blends were measured and the mechanism of effects of phosphorus were explored based on the results of X-ray diffraction (XRD), thermodynamic software FactSage, Fourier transformation infrared spectroscopy (FTIR) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). To eliminate the interference of calcium, a phosphorus-free control group was set up with CaCO 3 and the same tests were conducted. The experimental and modelling results showed that phosphorus had a significant fluxing effect on the fusion of coal ash by providing the initial liquid phase and changing the main minerals. The effects of phosphorus on slag viscosity were rather complex. At the temperature above 1530 °C, phosphorus-bearing slags had slightly higher viscosity values than phosphorus-free slags due to the increased polymerization degree of the network structure. However, at the cooling process, phosphorus restricted the crystallization in the slag and decreased the viscosity values and the temperatures of critical viscosity (T CV ). In this paper, a suitable addition ratio of Ca 3 (PO 4 ) 2 for the slagging gasification of HN coal was concluded.

Surface modification of malachite with tetraamminecopper (II) and its effect on sulfidation flotation

In view of the strong hydrophilicity of malachite, the sulfidation performance of conventional sulphidizing reagent sodium sulfide on malachite is not satisfactory. In this work, we discussed the effect of tetraamminecopper (II) complex pretreatment on the sulfidation and flotation behavior of malachite. The performance was evaluated by micro-flotation experiments. The flotation results showed that a better flotation recovery can be obtained with a molar concentration of tetraamminecopper (II) sulfate of only one-twentieth of the conventional activator (NH4)2SO4, all else being equal. Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS) shows that the weight percentage of S and Cu on the surface of the sulfidized malachite increased significantly in the present of [Cu(NH3)4]2+. The FTIR and Raman results showed that sulfur ions could be chemisorbed on the surface of malachite and form a layer of copper-sulfide species. X-ray photoelectron spectroscopy (XPS) further confirmed the actual existence of the sulfide layer, which consists of monosulfide (S2−), disulfide(S22−) and polysulfide (Sn2−). The presence of the activator [Cu(NH3)4]2+ can significantly increase the formation of disulfide and polysulfide on the surface of malachite, thereby promoting the subsequent interfacial adsorption of xanthate.

Effects of Coal Rank and Macerals on the Structure Characteristics of Coal-Based Graphene Materials from Anthracite in Qinshui Coalfield

Thirteen raw coal samples from Qinshui coalfield were prepared to produce coal-based graphene, and the raw coal, coal-based graphite, and coal-based graphene sheets (GS) were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy with energy dispersive spectrometer (SEM-EDS), and high-resolution transmission electron microscopy (HRTEM). The results show that the graphitization degree of coal-based graphite is positively linearly correlated with the reflectance of raw coal, has a low positive correlation with the content of inertinite, and has a low positive correlation with the content of vitrinite in raw coal. The crystallite width (La) and crystallite height (Lc) of coal-based graphite and graphene are positively linearly correlated with the reflectance of raw coal. La and Lc of coal-based graphite are distributed in 17.591–48.374 nm and 11.359–23.023 nm, respectively. After redox, La and Lc of coal-based graphene are distributed in 4.405 nm–6.243 nm and 0.804–1.144 nm, respectively. The defect degree (ID/IG) of coal-based graphene is higher than that of raw coal, demineralized coal, and coal-based graphite. The coal-based graphene is thin and transparent, and only contained carbon and oxygen. Combined with the parameters of XRD and HRTEM, it is calculated that the interlayer spacing (d002) of Qinshui-coal-based graphene is about 0.4007 nm and the number of layers (Nave) is about 5.

Removal of Cesium from Radioactive Waste Liquids Using Geomaterials

In this study, we investigated the removal of Cs from aqueous solutions using geomaterials. Adsorption was chosen as an effective method to develop for the removal of Cs from radioactive waste liquids. Geomaterials, including fly ash and slag as raw materials, were prepared as adsorbents using an alkali activator. The materials were characterized by X-ray diffraction (XRD); scanning electron microscopy with energy dispersive spectrometer (SEM-EDS); and BET surface area, pore volume, and pore size analysis. The effects of various parameters, such as pH, contact time, and adsorbent dosage on the adsorption of the Cs were studied. The partition coefficient (PC) as well as the adsorption capacity were evaluated to assess the true performance of the adsorbent in this work. The fly ash-based geomaterials showed a maximum Cs adsorption capacity of 89.32 mg·g−1 and a high PC of 31.02 mg·g−1·mM−1 for the Cs under our experimental conditions. From this work, this method can be regarded being practical for use as a potential adsorbent for treating Cs in wastewater. Furthermore, the immobilization of Cs in geomaterials was explored from a chemical perspective. In conclusion, fly ash-based geomaterials may be a promising option for the treatment and disposal of nuclear-contaminated waste.

The mutual effect and reaction mechanism of bitumen and de-icing salt solution

The two most used de-icing salts, sodium chloride and calcium chloride are detrimental to asphalt pavements during winter maintenance. However, limited research focused on the effect and mechanism of de-icing salt on bitumen. To fill the gap, this research aims to investigate the mutual effect and reaction mechanism between bitumen and de-icing salt solutions. 10% NaCl and 10% CaCl2 solutions were prepared to immerse neat bitumen and aged bitumen for 7, 28, and 90 days, respectively. The pH value of the salt solution, the morphology and element analysis, chemical structure, and rheological properties of the bitumen were evaluated by pH meter, scanning electron microscope with energy dispersive spectrometer (SEM-EDS), Fourier transform infrared (FTIR) radiation spectrometer with an attenuated total reflectance (ATR), and dynamic shear rheometer (DSR), respectively. After the immersion process, the pH value of the salt solution can decrease to 4.33; the bitumen surface became rougher, and O content of bitumen increased by 2%, around 1% Cl and Na/Ca element appeared; S = O, C = O, C-OH, C-Cl functional groups increased by up to 60%; and the bitumen showed sufficient deformation resistance and worse viscous behaviour. According to the test results, the reaction mechanism between bitumen and de-icing salt solutions was summarized into three sub-mechanisms: the release of hydrogen ions from the bitumen into the solution; the substitution reaction of Cl provided by de-icing salt; and the oxidative reaction between bitumen and oxygen.

Preparation, characterization and rheological analysis of eco-friendly road geopolymer grouting materials based on volcanic ash and metakaolin

Geopolymer has been applied in road engineering as an environmentally friendly material. This study prepared geopolymer road grouting pastes in different mixture ratios of volcanic ash (VA) and metakaolin (MK). The mechanical properties, setting time, bleeding and expansion ratio, fluidity and expansion ratio, time-dependent rheological analysis were systematically evaluated. Finally, the microscopic experiments, including X-Ray Diffraction, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive Spectrometer (SEM-EDS), were conducted to investigate the mechanism of geopolymerization based on VA and MK. The results showed that the mechanical strength increased with the content of MK. The flow curve of all pastes fitted the Bingham model. With the increase of MK content, the yield stress and plastic viscosity coefficient increased, which is because the stacked multilayer gullies microstructure aggravated the internal friction of paste particles, which led to decreased expansibility and pumpability. When the mass ratio of VA/MK was 1:0.33, the paste achieved the balance of mechanical strength and rheological properties with superior water retention and deformation resistance. The microscopic experiments showed that MK's mechanism enhanced the mechanical strength of geopolymer due to its high content of amorphous phases, smaller average particle size, and rich content of Al element. The SEM-EDS indicated that the MK improved the mechanical strength also by the improvement of nucleation effect. VA and MK complement each other in mechanical strength development under room temperature and fluidity, which are expected to be an alternative for cement as an eco-friendly road grouting material.

The Preparation and Characteristics of a Blue Pearlescent Pigment with LTA-Type Ultramarine Coated on the Mica Substrate

Ultramarine is a nontoxic and cheap inorganic pigment, which has been rarely used in blue pearlescent pigments. This work reports the synthesis of nano-ultramarine with LTA structure by calcining the polysulfide impregnated zeolite at 600∘C for 1[Formula: see text]h. Then the ultramarine colored mica composite was prepared by using [Formula: see text]-(2,3-epoxypropoxy) propytrimethoxysilane (KH-560) to attach ultramarine to the mica substrate through a covalent bond. Scanning electron microscope with energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet and Visible Spectrophotometry (UV-Vis) were employed to characterize the structure and properties of the ultramarine, composites as well as the intermediates. The results showed that LTA framework was retained in ultramarine during the calcination at the temperature below 700∘C. The FTIR spectra demonstrated that ultramarine was successfully modified by KH-560. The SEM, UV-Vis and [Formula: see text]*[Formula: see text]*[Formula: see text]* values revealed the increasing the amount of KH-560-modified ultramarine contributing to the formation of the dense coating layer on mica and changed the color of the ultramarine-coated mica composite. The optimum mass ratio of mica to ultramarine was 1:2 and the composite demonstrated an ideal blue pearlescent effect.

The distribution characteristics of brittle minerals in the Lower Cambrian Niutitang Formation in northern Guizhou

To explore the influence of brittle mineral composition and morphological characteristics within the shale matrix on the generation of complex fractures and reservoir reconstruction, the microstructure and fractal characteristics of minerals within the shale matrix of the Lower Cambrian Niutitang formation in northern Guizhou were investigated using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS), and micro-computed tomography (Micro-CT). Based on image processing technology and digital core modelling, a three-dimensional shale digital core model was established. The distribution and morphological characteristics of brittle minerals within the shale matrix were studied from the fractal perspective. The model for evaluating the mineral particles and pores within the shale matrix was established. The results show that the siliceous mineral composition is high, and it is mainly derived from the interaction of continental detrital quartz particles and biogenetic effects; the density of the brittle minerals is greater than other mineral components mainly distributed in the range of equivalent diameters of 200–800 μm; the distribution complexity of the brittle minerals was quantitatively analysed from the fractal perspective; the fractal dimension partly reflects the generating ability of complex fractures; the distribution angle and complexity of brittle mineral particles within the shale matrix partly determine the fracture morphology characteristics. The physical properties of shale reservoirs were studied from three aspects: complex fracture generation ability, pore connectivity and heterogeneity, and the evaluation model of mineral particles and pores was established using the value of fractal dimension, ratio of organic matter pores, tortuosity of pores, relative deviation of pore size distribution, and relative deviation of specific surface area. The model provides a basis for further study on the relationship between reservoir reconstruction potential and physical properties of shale reservoirs.

Qualitative and relative distribution of Pb2+ adsorption mechanisms by biochars produced from a fluidized bed pyrolysis system under mild air oxidization conditions

Qualitative and relative distribution of Pb2+ adsorption mechanisms was investigated using corn stalk biochars (CSBs) and rice husk biochars (RHBs) produced from a pilot-scale fluidized bed pyrolysis system under mild air oxidization conditions (oxygen content 0–6%) at low temperature (450 °C). Boehm titration, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS) were used to analyze the characteristics of biochars, and adsorption isotherms and kinetics analysis were studied. The Pb2+ adsorption capacities of CSBs (about 40 mg/g) presented about twice the amount of RHBs (about 22 mg/g), which were mainly caused by cation exchange and precipitation mechanisms, with the contribution content to the total sorption up to 90%. With oxygen content increasing from 0% to 6%, the absorbed lead capacity due to cation exchange of CSBs increased from 19.10 to 30.40 mg/g, and the corresponding contributions to total Pb2+ sorption increased from 49.00% to 73.80%. When the oxygen content of pyrolysis atmosphere increased, the contribution of cation exchange in Pb2+ adsorption exhibited extremely different tendencies in CSBs and RHBs under the combined action of metallic accumulation in ash and non-active silica embedding in the retract process, which plays a dominant role in Pb2+ adsorption. This study suggests that CSBs produced by fluidized bed under mild air oxidation improved cation exchange capacity, and were promising, low-cost biochar for Pb2+ remediation in the aqueous environment.

Investigating the adsorption behavior and quantitative contribution of Pb2+ adsorption mechanisms on biochars by different feedstocks from a fluidized bed pyrolysis system

The aim of this study was to examine the qualitative and quantitative analysis of Pb2+ adsorption mechanisms performed with biochars derived from rice straw (RSBs), rice husk (RHBs) and saw dust (SDBs) at several pyrolysis temperatures (400-600 °C) in a fluidized bed system. Adsorption isotherms, kinetics, and desorption analysis were determined, and biochars were analyzed by X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS) and Boehm titration method. The effect of minerals on Pb2+ adsorption, including precipitation and cation exchange, revealed increasing contribution of precipitation from a range of 4.13%–38.83% to a range of 34.08%–79.94% and decreasing effect of cation exchange from a range of 50.17%–69.75% to a range of 9.57%–43.47% with increasing pyrolysis temperature. However, it remained the dominant adsorption mechanism of all biochars (accounted for 69.49–89.52%). Especially, RSBs with quite high maximum adsorption capacity (qm) values (116-127.57 mgg−1) were mainly due to precipitation mechanism of Pb2+ adsorption, which exhibited better adsorption capacities than RHBs (25.15–30.40 mgg−1) and SDBs (21.81–24.05 mgg−1). Only with the fluidized bed shown in this study, 2.00t RSBs could be produced and the corresponding Pb2+ adsorption may reach 255.50kg per year depending on its maximum adsorption capacity under 500 °C pyrolysis temperature. The results suggest that RSBs produced in a fluidized bed reactor is a promising, cost-effective, engineered biochar for application of Pb2+ remediation in aqueous solutions.

Immobilized laccase on magnetic nanoparticles for enhanced lignin model compounds degradation

Abstract As a natural aromatic polymer, lignin has great potential but limited industrial application due to its complex chemical structure. Among strategies for lignin conversion, biodegradation has attracted promising interest recently in term of efficiency, selectivity and mild condition. In order to overcome the issues of poor stability and non-reusability of enzyme in the biodegradation of lignin, this work explored a protocol of immobilized laccase on magnetic nanoparticles (MNPs) with rough surfaces for enhanced lignin model compounds degradation. Scanning electron microscope with energy dispersive spectrometer (SEM-EDS), flourier transformation infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA) were utilized to characterize the immobilization of laccase. The results showed a maximum activity recovery of 64.7% towards laccase when it was incubated with MNPs and glutaraldehyde (GA) with concentrations of 6 mg·ml−1 and 7.5 mg·ml−1 for 5 h, respectively. The immobilized laccase showed improved thermal stability and pH tolerance compared with free laccase, and remained more than 80% of its initial activity after 20 days of storage at 4 °C. In addition, about 40% residual activity of the laccase remained after 8 times cycles. Gas chromatography–mass spectrometry (GC–MS) was utilized to characterize the products of lignin model compound degradation and activation, and the efficiency of immobilized laccase was calculated to be 1–5 times that of free laccase. It was proposed that the synergistic effect between MNPs and laccase displays an important role in the enhancement of stability and activity in lignin model compound biodegradation.

Two advanced oxidation pathways of modified iron-shavings participation in ozonation

In this study, the performance of ozonation, catalytic ozonation and activation of molecular oxygen (AMO) process was examined with oxalate as the target refractory organics. Modified iron-shavings was used as catalyst for catalytic ozonation in degradation of oxalate at ambient temperature (25 ± 2 °C). Under catalytic ozonation, the removal of oxalate was as high as 90%, which was much better than ozone alone. Initial pH was a key factor affecting the mechanisms of oxalate degradation. In AMO process, with the existence of Fe (II) there occurred an inner-Fenton reaction, hydrogen peroxide (H2O2) was produced at initial pH2.27 and its concentration ranged from 120 to 200 μmol/L. Heterogeneous catalytic ozonation occurred in alkaline solution with hydroxyl radicals (·OH) production, which was indirectly oxidation instead of inner-Fenton reaction. Carbonate would be produced in alkaline solution during catalytic ozonation of oxalate which would in turn inhibit the process. Lepidocrocite (γ-FeOOH) was formed through the dissolved iron ions precipitation and considered as the main component of catalyst, which was confirmed via field emission scanning electron microscope with energy-dispersive spectrometer (SEM-EDS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Hydroxyl radicals produced via different paths were detected out by electron paramagnetic resonance (EPR) and were considered as strong oxidant in catalytic ozonation and AMO process.

Microwave improving copper extraction from chalcopyrite through modifying the surface structure

Microwave-assisted leaching as a green and efficient method for leaching chalcopyrite has attracted increasing attention. Researchers have actively explored the reasons why microwaves have a positive impact on copper extraction. In this work, X-ray diffraction (XRD), an optical microscope, electron probe micro-analyzer (EPMA) and field emission scanning electron microscope with energy dispersive spectrometer (SEM-EDS) were employed to investigate the surface structure modification of chalcopyrite by microwave during leaching. The modified chalcopyrite had a positive effect on better mineral leachability, higher effective surface for leaching, and the fewer passivation layer. The superior mineral leachability was related to the surplus intermediate products of covellite, while microwave promoted the conversion of chalcopyrite to covellite. In addition, microwave is capable of increasing active sites upon the removal of the passivation layer and the enlargement of the effective reaction surface. This work summarized the relationship between the high copper recovery and the surface structure modification of chalcopyrite systematically.

Adsorption characteristics and mechanism of Pb(II) by agricultural waste-derived biochars produced from a pilot-scale pyrolysis system

The objective of this study was to investigate the feasibility of removing Pb2+ by pilot-scale fluidized bed biochar, and then to put forward an industrial-scale fluidized bed pyrolysis progress of cogeneration of biochar and high-temperature gas. Corn stalk biochars (CSBs) were prepared at 400–600 °C, in which the maximum Pb2+adsorption capacity (Qm) of CSB450 is 49.70 mg⋅g−1 at the optimal condition. Adsorption isotherms, kinetics, and thermodynamics were determined, and Pb2+-loaded biochar was analyzed by fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Ion exchange, complexation and mineral precipitation together contributed to Pb2+ adsorption on CSBs. For high-temperature CSBs with fewer oxygen functional groups (OFGs) and stronger aromatization, Pb2+ adsorption by ion exchange and functional group complexation was reduced. The mineral precipitationwas formed during the adsorption process. Using the pilot-scale fluidized bed in this study, the carbon yield per year would achieve 31.79 t, and about 1.58 t of Pb2+ would be adsorbed according to the adsorption capacity at the pyrolytic temperature of 450 °C.The results are beneficial to screen for effective biochar as a cost-effective industrial adsorbent to remove Pb2+ in contaminated water.

Removal of gaseous elemental mercury by hydrogen chloride non-thermal plasma modified biochar.

Hydrogen chloride (HCl) non-thermal plasma was applied to introduce Cl active sites on biochar prepared from sorghum straw in this study. Surface modified biochar was then placed in flue gas with typical components to investigate its elemental mercury (Hg0) capture ability. To elucidate the adsorption mechanism & binding properties, samples were characterized by N2 adsorption, scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and X-ray absorption near edge structure (XANES) analysis of Hg LIII-edge, Cl K-edge and S K-edge. Experimental results showed that HCl plasma modification successfully increased Cl active sites on biochar and greatly increased its mercury removal efficiency. Both HCl treatments (w/without plasma involvement) altered biochar's surface structure and layered structure generated. XANES spectra revealed that adsorbed-Hg on HCl-treated biochars mainly in the form of Hg+. Gaseous Hg0 was believed to heterogeneously react with chlorinated sites through electron-transfer and formed Hg2Cl2 compounds. With the presence of NO or SO2 in the system, adsorbed mercury existed on biochar mainly as Hg+. SO2 competed and inhibited the adsorption of Hg0; while NO promoted Hg0 removal capacity by increasing the active sites and enhancing the adsorption kinetics of adjacent Cl-containing sites.