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A void zone, the so-called raceway, may be formed when gas is laterally injected into a particle packed bed and the char particles may combust when the gas enters at a high temperature for example coke combustion in the raceway of ironmaking blast furnaces. Experimental and numerical studies of multiphase flow in the raceway have been conducted widely in recent years, however, the study of reacting flows in the raceway is still limited at a particle scale. This work is to study the gas-solid reacting flows in the raceway using a particle scale CFD-DEM approach, featuring heat and mass transfers and chemical reactions between the gas and solid phases. The simulation results are comparable with the measurements in the physical experiments and previously calculated results. The key phenomena of flow and thermochemical behaviour related to the raceway formation at the particle scale are obtained. Then the model is used to study the dependency of raceway formation and thermochemical behaviour on several key raceway variables including gas inlet velocity, particle size, bed height and particle discharge rate. The simulation results indicate that before generating a stable raceway, a larger blast inlet velocity or a larger discharge rate can form a larger raceway cavity, while the effect of packed bed level shows an opposite trend. The model provides fundamental insights into the complex reacting flows in the raceway zone for a better understanding and optimization in operations.

p-Arsanilic acid (p-ASA) is widely used as feed additives in animal production, and its transformation in environment media may cause arsenic contamination of soils and waters. It is essential to find a technology to effectively treat p-ASA, and meanwhile greatly decrease the mobility of the arsenic. Herein, we propose a disilicate-assisted Fe/Al electrolysis (D-FeAl-E) process for the degradation of p-ASA and the subsequent immobilization of inorganic arsenic. The results showed that, in the first stage of D-FeAl-E, namely the iron anode electrolysis process with disilicate, p-ASA was degraded by 92% under a near-neutral condition. The efficient degradation of p-ASA could be attributed to the disilicate-coordinated electrolytic ferrous ions, which activated dioxygen to produce more reactive oxygen species (e.g., O2−, H2O2 and OH in this study) to attack p-ASA molecules. Following the first stage, the produced inorganic arsenic and other intermediates can be further removed in the second stage of D-FeAl-E process (the Al anode electrolysis), via the coagulation effect initiated by the electrogenerated hydroxylated aluminum species. Electrogenerated Al(III) ions hydrolyzed into positively charged monomeric/oligomeric Al species, which could result in the dissociation of disilicate-Fe(III) complexes, and the formation of hydroxides and oxo-bridging polynuclear entities for arsenic immobilization. Leaching stability tests suggested that the D-FeAl-E process was superior to the conventional electrocoagulation method with respect to the stability of the generated arsenic-containing solid sludge. The D-FeAl-E process is free of the use of chemical oxidants and coagulants, but it provides both oxidation and coagulation effects for the abatement of p-ASA during the two-stage electrolytic process. Therefore, it is expected to be engineered as efficient and compact electrochemical technology capable of providing both oxidation and coagulation effect for decontamination.

The Fe−Si−Zr alloys have attracted considerable interests in recent decades. It is important to study this ternary phase diagram for experimental design. In this paper, the Fe−Si−Zr ternary system is investigated by combining the experiments and thermodynamic calculations. Liquidus surface projection of the Fe−Si−Zr system is characterised using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and differential thermal analysis (DTA). The liquidus projection of this ternary system is constructed by identifying primary crystallization phases and invariant reaction temperatures in the as-cast alloys. Eleven different primary solidification regions are observed. Based on the experimental results of this work and the data from the previous work in the literature, the thermodynamic calculation of the Fe−Si−Zr system is performed using CALPHAD (CALculation of PHAse Diagrams) technique. A set of self-consistent thermodynamic parameters of the Fe−Si−Zr system is obtained. The calculated results are in good agreement with the experimental data. This study provides a set of reliable thermodynamic parameters to the Fe-based thermodynamic database, and a cost-effective tool to design experiments and manufacturing processes.

Removal of excessive nutrients (N and P) is one of the most concerned issues for wastewater treatment. This study presents a paired electrolytic system consisting of Al cathode and RuO2/Ti anode for the simultaneous removal of phosphate and ammonia in wastewaters. The comparative study on the dissolving behaviors of Al cathode and Al anode showed that Al cathode could achieve a continuous and stable dissolution of aluminum, thereby forming flocs and small amounts of water soluble aluminum species for decontamination. The electrogenerated OH– in the vicinity of cathode raised the local alkalinity and caused the chemical dissolution of aluminum. According to the experiment of non-electrolytic dissolution of aluminum in alkaline solution, the local pH resulting in the cathodic dissolution of Al was estimated. The paired electrolytic system showed the capability to simultaneously remove ammonia and phosphate in simulated wastewater, and the pH neutralizing effect in association with the formation of Al species could promote the electrochemical oxidation of ammonia. When the paired electrolytic system was applied to the treatment of landfill leachate, 96.9% of ammonia nitrogen, 87.4% of total phosphorous and 89.9% of COD could be eliminated after three hours of electrolysis at 80 mA/cm2. The results shown in study reveal that the dissolution process of Al cathode enables a convenient control on the dissolving-out amounts of aluminum via regulating the applied current density, and the paired electrolytic system can be developed as an energy-efficient electrochemical wastewater treating method.

Sb2S3 and CuSbS2 have been proposed as alternative earth-abundant absorber materials for thin-film solar cells. However, no thermodynamic study of the S−Sb binary system and the Cu−S−Sb ternary system were investigated. In this paper, The S−Sb system and the Cu−S−Sb system are calculated utilizing the so-called CALPHAD (CALculation of PHAse Diagrams) technique. Using TEM-EDS and XRD, Cu0.9Sb1S2 is experimentally confirmed at the Cu1Sb1S2 and Sb2S3 two-phases region in the isothermal section at 673 K of the Cu−S−Sb ternary system. Given the asymmetric shape and miscibility gap of the liquidus in the S−Sb phase diagram, the associate solution model for the liquid phase is adopted. The solution phases (liquid, bcc, fcc) are treated with the Redlich–Kister equation. The compounds S3Sb2, Cu3SbS3, Cu12Sb4S13, CuSbS2, and Cu3SbS4 are described as a stoichiometric compound. A set of self-consistent thermodynamic parameters of the S−Sb binary system and the Cu−S−Sb ternary system are obtained. The calculated results are in good agreement with the experimental data. This study provides a set of reliable thermodynamic parameters to the Cu−Sb−S thermodynamic database, and a cost-effective tool to design material synthesis experiments and manufacturing processes.

The phase equilibria and thermodynamic properties of the Al–Ge–Ni system are useful for understanding the diffusion process during the transient liquid phase (TLP) bonding. In this work, the thermodynamic description of the Al–Ge–Ni system over the whole composition and temperature ranges was performed by means of the CALPHAD (CALculation of PHAse Diagrams) method. The enthalpies of mixing of the liquid phase, three isothermal sections at 973, 823, and 673 K and nine vertical sections at 10, 20, 35, 55, 60, 70, 75, and 80 at% Ni and at a constant Al:Ni ratio of 1:3 were taken into account in the present optimization work. A set of self-consistent thermodynamic parameters of the Al–Ge–Ni system was first obtained. The liquidus projection and reaction scheme were constructed according to the thermodynamic parameters obtained in this work. The phase equilibria and thermodynamic properties calculated by the present thermodynamic description show satisfactory agreement with the available experimental information.

The present study demonstrates the effectiveness of a novel oxidant system, namely the combined use of peroxymonosulfate (PMS) and permanganate (CUPP), for the degradation of benzene and trichloroethylene (TCE) in simulated groundwater. The CUPP process exhibited favorable oxidizing capability because the in-situ generated colloidal and amorphous MnO 2 linked the two oxidants. Compared with the separate use of permanganate or peroxymonosulfate, the CUPP process showed much better efficiency for the removal of refractory benzene. According to the electron paramagnetic resonance analysis and PMS-activating experiments, both colloidal and amorphous MnO 2 (AM-MnO 2 ) triggered the radical-mediated oxidation, but the AM-MnO 2 -activated PMS showed an adsorption-dependent oxidizing capability. For the CUPP process, higher temperatures promoted the initial degradation rate of benzene, but did not change its final removal efficiency. The degradation of benzene was mostly associated with the activated PMS, and the intermediates also competed with TCE for KMnO 4 . The KMnO 4 component played a more important role than PMS for the removal of TCE. For an aqueous mixture of 0.3 mM benzene and TCE, the combination of 2.4 mM PMS and 1.8 mM KMnO 4 was optimal, achieving removal efficiencies higher than 85% for both pollutants. Regarding the degradation of benzene, chloride ions had a concentration-dependent effect, and bicarbonate ions and dihydrogen phosphate showed different levels of retarding effect. The CUPP is envisaged to be used as a remedial reagent for the in-situ chemical oxidation of groundwater contaminants.

The isothermal sections at 1073 and 1273 K, and liquidus surface projection of the Ti–V–Zr system were investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and differential thermal analysis (DTA). Combined with experimental results in the present work and literature, the Ti–V–Zr system was optimized by the means of the CALPHAD (CALculation of PHAse Diagram) method. The solution phases, liquid, hcp (Ti, Zr) and bcc (Ti, V, Zr), were modeled with the substitutional solution model, and the compound V 2 Zr was treated as (Ti, V, Zr) 2 (Ti, V, Zr) based on its thermodynamic model in the V–Zr system and the experimental solid solubility of Ti in the Ti–V–Zr system. A set of self-consistent thermodynamic parameters of the Ti–V–Zr system was obtained.

The V–Zr system was investigated by experiments and thermodynamic modeling. In experiments, 10 crucial alloys were selected, and the microstructure, crystal structure and phase transformation temperatures of the alloys were obtained using scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS), X-ray powder diffraction (XRD) and differential thermal analysis (DTA). A thermodynamic modeling of the V–Zr system was then performed by considering the reviewed literature data and incorporating the present experimental results. The solution phases, liquid, hcp (Zr) and bcc(V, Zr), were modeled with the substitutional solution model, and the compound V 2 Zr was treated as (V, Zr) 2 (V, Zr) by means of two-sublattice model. A set of self-consistent thermodynamic parameters of the V–Zr system was obtained.

This work proposes an anti-corrosive nanofibrous membrane by combining one-pot solvothermal reduction method and electrospinning technology as a solution to the ever-increasing water pollution issues. Such membrane is made of aromatic polymer-polyimide and further modified by reduced graphene oxide, which maintained the original performance under different external environment and multi-cycled test, and achieved high separation efficiency (99.19%) and flux (2040.04 L m-2h−1) at the same time. The purification process is suitable for various contaminants and different combinations. Additionally, the inherent purification mechanism was fully explored in this study. The practicability of the membrane can be tested for the contaminated water purification, the recycle of poisonous and harmful substances, pre-process of precision extraction and so on.

The feasibility of using polymer‑carbon composite material (PCCM) substrate, instead of titanium substrate, for the preparation of PbO2 electrode was explored. The preparation procedure was optimized to maximize the performance of the PbO2 anodes. Our investigation shows that introducing α-PbO2 interlayer could significantly enhance the bonding of the surface β-PbO2 with the substrate. The addition of fluoride ions in the electrodeposition electrolyte could refine the grain size of the β-PbO2, resulting in a dense and smooth surface to enhance the service life of the composite anode. Therefore, the electrode PCCM\α\F−-β-PbO2, which had a α-PbO2 interlayer and a fluoride doped β-PbO2 surface layer, showed the longest accelerating life. The results of experiments also showed that the current density and deposition time significantly affected the surface morphologies of the PbO2 composite electrode. The optimal condition for the deposition of F−-β-PbO2 surface layer was 1 h of operation at 10 mA/cm2 current density, and this condition allowed to offer the electrode with a compact surface to prevent the penetration of caustic electrolyte and an appropriate thickness to avoid the strong internal stress. It was also found that the PCCM\α\F−-β-PbO2 exhibited the same electrocatalytic activity as that of the Ti-substrate counterpart electrode for the electrochemical oxidation of 2,4-dichlorophenol. This study indicates that the PCCM substrate can be used as an alternative substrate for the preparation of affordable PbO2 anode for non-heavy duty applications.

The unique characteristics of H2O2 render it a versatile and green agent for environmental remediation applications. As an essential component of a classic Fenton or Fenton-like reaction, H2O2 can effectively decompose aqueous refractory contaminants via the large amounts of reactive oxygen species produced. There is increasing interest in developing decentralized H2O2 production methods that can greatly reduce the risks and costs of H2O2 storage, transportation, and use for oxidative reactions. The on-site activation of molecular oxygen is an ideal way to produce H2O2 for decontamination since oxygen is safe and readily available. Understanding the behaviors of O2 activation by different reductants is essential in optimizing the selectivity of H2O2 production, removal efficiency, and the functioning of a specific catalyst. In this review, the on-site generation of H2O2, including zero-valent metals, ferrous iron species, catalytic H2 reduction, and the photocatalytic activation route are critically reviewed and discussed from the fundamental aspects to their environmental applications. We hope that this review not only deepens understanding of the on-site generation of H2O2 by O2 activation, but also give pointers to further studies in this important field.

BACKGROUND Electrolysis with an iron anode is a novel way to provide ferrous activators for chemical oxidation. The objective of this study is to evaluate the performance of peroxymonosulfate (PMS) for chlorophenol destruction when compared with H2O2 and persulfate (PS), and to see whether the electrolysis mode facilitates the buildup of conditions that favor the activation of PMS and removal of chlorophenols. RESULTS Ferrous species can effectively activate the PMS over a wide pH range. In comparison with H2O2 and PS, PMS is less sensitive to the solution's pH and possesses stronger oxidation capability at alkaline pHs. The optimal molar ratio of PMS to Fe(II) activator is 1:1 for the destruction of 2,4-dichlorophenol (2,4-DCP). The column experiments show that an acidic zone developed downstream from the anode is favorable to maintain ferrous ions and subsequent activation of PMS. The reactivity of the PMS can be manipulated by varying the electrical currents, and the process demonstrates effectiveness for treating organic contaminants. 2,4-DCP contaminated groundwater shows decreased biotoxicity after the chemical oxidation process without considering the residual PMS. CONCLUSIONS Iron electrolysis-assisted peroxymonosulfate chemical oxidation can effectively treat the 2,4-dichlorophenol and mixtures of organic contaminants. This process can be engineered as an in situ chemical oxidation method for groundwater remediation. © 2015 Society of Chemical Industry

The Gd–Pb system was critically modeled by means of the CALPHAD technique on the basis of experimental data in the literature. Given the asymmetric shape of the liquidus in the Gd–Pb phase diagram, the associate model for the liquid phase was tested and compared with the substitutional solution model. The results of the optimization show that a better agreement with the available experimental data is obtained by means of the associate model than the substitutional solution model. The solution phases (liquid, bcc, fcc, hcp) were treated with the Redlich–Kister equation. The intermetallic compounds Gd 5 Pb 3 , αGd 5 Pb 4 , βGd 5 Pb 4 , Gd 11 Pb 10 , Gd 6 Pb 7 , GdPb 2 , GdPb 3 were treated as stoichiometric compounds. Two sets of self-consistent thermodynamic parameters of the Gd–Pb system were obtained.