[en] Highlights: • Novel visible-light-activity β-Bi₂O₃/TiO₂-NTs are constructed by bidirectional doping. • TiO₂-NTs visible-light absorption edge extends to 495 nm by Bi species modification. • β-Bi₂O₃ oxidability is enhanced (VB from 2.02 to 2.28 eV) by Ti species modification. • β-Bi₂O₃ stability is enhanced by Ti atoms doping and TiO₂-NTs stake structure. • p–n heterojunction is formed and the photoconversion efficiency is improved. -- Abstract: Stable β-Bi₂O₃/TiO₂-NTs photocatalyst with excellent visible-light-activity is successfully prepared by bidirectional doping. Stake structure of the TiO₂-NTs provides a larger specific surface area and makes the contact area between the TiO₂-NTs and β-Bi₂O₃ much larger; The stake structure of TiO₂-NTs not only leads to a firmer combination of TiO₂-NTs and β-Bi₂O₃, but also makes them dope one another deeply. The modification of Bi species into TiO₂-NTs can form Bi-O-Ti chemical absorption bonds, then a localized impurity level is generated within the band gap. Electrons can be excited and transferred from the Bi³⁺ impurity level to the conduction band (CB) of TiO₂, similar to narrowing the band-gap of TiO₂-NTs, resulting in a red shift of the absorption edge and an enhancement in visible-light activity. During annealing, Bi atoms are partially replaced by Ti atoms. The lattice of β-Bi₂O₃ is compressed around the Ti impurity, making the lattice dislocate and distort. This dislocation and distortion leads to an increase in the β-Bi₂O₃valance band (VB), from 2.02 to 2.28 eV. Accordingly, the weak oxidability of β-Bi₂O₃ is improved, and its photocatalytic ability is further enhanced. Moreover, this lattice dislocation and distortion changes the Bi-O distances, thus remarkably improving the stability of the β-Bi₂O₃/TiO₂-NTs

[en] Graphical abstract: - Abstract: SnO₂ photonic crystal (SnO₂ PC) sensitized with CdS quantum dots (SnO₂ PC/CdS QDs) was structured on FTO substrate to enhance photocatalysis. Scanning electron microscopy indicated that the CdS QDs with an average of 5 nm to 10 nm were dispersed uniformly into the SnO₂ PC. The results of the transmittance spectra indicated that the light absorption was redshifted to 500 nm, and that the optical absorption for SnO₂ PC/CdS QDs was sharply more than for the SnO₂ film in the 400 nm to 600 nm ranges. Meanwhile, good match between the peak position of photonic band gap (PBG) and the absorption of CdS enhanced the photoconversion efficiency up to 16.8 times and improved the photocurrent up to 9 times than that of SnO₂ film. The Bode phase plot of the samples were also conducted to further demonstrates the lower recombination of the photogenerated carriers. After 3 hours’ treatment, the removal rate of carbamazepine (CBZ) on SnO₂ PC/CdS QDs was 98.8%, and the rate constant (k) on SnO₂ PC/CdS QDs was 12.5 times than that on the SnO₂ film/CdS QDs

[en] Plasma electrolytic oxidation (PEO) films on AZ31 magnesium alloys were prepared in alkaline silicate electrolytes (base electrolyte) with the addition of different volume concentrations of CH_3OH, which was used to adjust the thickness of the vapor sheath. The compositions, morphologies, and thicknesses of ceramic layers formed with different CH_3OH concentrations were determined via X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion behavior of the oxide films was evaluated in 3.5 wt.% NaCl solution using potentiodynamic polarization tests. PEO coatings mainly comprised Mg, MgO, and Mg_2SiO_4. The addition of CH_3OH in base electrolytes affected the thickness, pores diameter, and Mg_2SiO_4 content in the films. The films formed in the electrolyte containing 12% CH_3OH exhibited the highest thickness. The coatings formed in the electrolyte containing different concentrations of CH_3OH exhibited similar corrosion resistance. The energy consumption of PEO markedly decreased upon the addition of CH_3OH to the electrolytes. The result is helpful for energy saving in the PEO process. (paper)

[en] A numerical simulation study of concrete bridge deck unbounded prestressed with CFRP tendons was developed and a verification analysis through ANSYS based on a type of concrete bridge deck with prestressed CFRP tendons was designed. By using the ANSYS model, this paper further studied the parametric sensitivity analysis on static load performance of concrete bridge deck unbonded partially prestressed with CFRP bars. The results show the influence on component strength and mechanical properties caused by factors in concrete bridge deck with prestressed CFRP tendons. (paper)

[en] The synchronous construction method of tower and beam can greatly shorten the construction period of cable-stayed bridge, but the force condition is complicated. The overall stability of the bridge which use synchronous construction method should be studied further. Based on the Dingzihekou Bridge project, a finite element analysis model was established and three typical construction conditions were selected by using Midas Civil software. Linear stability analysis and geometric non-linear stability analysis about the construction period of the Dingzihekou Bridge were conducted. The stability factors of the two construction schemes and the modes of the linear instability failure in the construction periods of the cable-stayed bridgeare inferred. It is found that the geometrically non-linear stability safety factor is significantly less than the linear. There is no big difference in linear stability factor between synchronous construction and asynchronous construction of tower and beam. As for the geometric nonlinear stability analysis, the synchronous construction of tower and beam has a larger stable safety factor than asynchronous construction. (paper)

[en] Indium and its compounds have plenty of industrial applications and high demand. Therefore, indium recovery from various industrial effluents is necessary. It was sequestered by nanoscale zero-valent iron (nZVI) whose size mainly ranged from 50 to 70 nm. Adsorption kinetics and isotherm, influence of pH, and ionic strength were thoroughly investigated. The reaction process was well fitted to a pseudo second-order model, and the maximum adsorption capacity of In(III) was 390 mg In(III)/g nZVI similar to 385 mg In(III)/g nZVI at 298 K calculated by Langmuir model. The mole ratio of Fe(II) released to In(III) immobilized was 3:2, which implied a special chemical process of co-precipitation combined Fe(OH)_2 with In(OH)_3. Transmission electron microscopy with an energy-disperse X-ray (TEM-EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize surface morphology, corrosion products, and valence state of indium precipitate formed on nanoparticles. The structural evolution changed from core-shell structure of iron oxide to sheet structure of co-precipitation, to sphere structure that hydroxide gradually dissolved as the pH decreased, and to cavity structures for the pH continually decreased. Furthermore, below pH 4.7, the In(III) enrichment was inhibited for the limited capacity of co-precipitation. Also, it was found that Ca"2"+ and HPO_4"2"− have more negative influence on In(III) recovery compared with Na"+, NO_3"−, HCO_3"−, and SO_4"2"−. Therefore, the In(III) recovery can be described by a mechanism which consists of adsorption, co-precipitation, and reduction and was over 78% even after 3 cycles. The results confirmed that it was applicable to employ nZVI for In(III) immobilization.

[en] Highlights: • A series of OMFMs were successfully fabricated via a novel inverse micelle method. • Calcination temperature affected the nanostructure and surface chemistry of OMFMs. • SiO₃²⁻/PO₄³⁻ ions and HA significantly influenced on both As(III) and As(V) removal. • Redox transformation of arsenic in liquid-solid phase was simultaneously investigated. • Respective role of Fe/Mn oxides in OMFM-3 for arsenic removal was identified. A series of ordered mesoporous FeMn bimetal oxides (OMFMs) were fabricated by using a novel inverse micelle method, and the texture, nanostructure and interface chemistry properties of OMFMs were closely correlated to the calcination temperature. Due to the amorphous regular inner-connected nanostructure and bimetallic synergistic effect, the obtained OMFMs exhibited superior arsenic sequestration performance than pure mesoporous Fe oxides (PMF) and Mn oxides (PMM). The optimum ratio of Fe/Mn and calcination temperature for arsenic removal was 3/1 and 350 °C (OMFM-3), and the maximum As(III) and As(V) adsorption capacities of OMFM-3 were 174.59 and 134.58 mg/g, respectively. Solution pH value negligibly affected the uptake of arsenic (ranged from 3.0 to 7.0), while SiO₃²⁻/PO₄³⁻ ions and humic acid (HA) displayed significant inhibitory effect on arsenic removal by OMFM-3. According to the mechanism of arsenic removal, which simultaneously analyzed the arsenic redox transformation in aqueous phase and on solid phase interface, it was concluded that manganese oxides in OMFM-3 mainly played the role as a remarkable As(III) oxidant in water, whereas iron oxides dominantly acted as an excellent arsenic species adsorbent. Finally, the prominent arsenic sequestration behavior and performance in surface water suggested that OMFM-3 could be a promising and hopeful candidate for arsenic-contaminated (especially As(III)) surface water and groundwater remediation and treatment.

[en] Highlights: • Biochar-supported MnFe₂O₄ magnetic nanocomposite (BC-MF) was successfully fabricated. • Adsorption behavior for p-ASA and As(V) was favorable at acidic and neutral pH. • Di-anionic and mono-anionic forms of p-ASA and As(V) promoted the adsorption process. • Remarkable removal of p-ASA and As(V) by xed-bed column in single and binary systems. • Simultaneous removal of organic and inorganic arsenic species was achieved by BC-MF. To solve the problem of organic and inorganic arsenic species contamination in drinking water and/or wastewater, porous biochar-supported MnFe₂O₄ magnetic nanocomposite (BC-MF) was successfully fabricated and used as an excellent adsorbent for simultaneous removal of p-ASA and As(V) from water environment. This obtained BC-MF displayed remarkable adsorption performance for both p-ASA and As(V) removal at acidic and neutral pH (3−7), and di-anionic and mono-anionic species of p-ASA and As(V) facilitated the adsorption process. Specifically, BC-MF exceeded some reported adsorbents, and the adsorption capacities of p-ASA and As(V) were approximately 105 and 90 mg/g at a 10 μg/L equilibrium concentration. Satisfactory adsorption behavior including adsorption isotherms, competitive ions, humic acid (HA), and regeneration/reusability property in single and binary systems demonstrated the BC-MF can improve the potential application for arsenic-containing wastewater remediation. Proposed adsorption mechanism indicated that electrostatic interaction and surface complexation were involved the p-ASA and As(V) immobilization, whereas hydrogen bonding and π-π interactions may also contribute to the p-ASA removal. Additionally, the prominent sequestration p-ASA and As(V) performance in different water matrix and xed-bed column studies indicated that BC-MF was a promising nanocomposite for simultaneously removal of organic and inorganic arsenic species in practical wastewater treatment.

[en] This study investigates the application of nanoparticle zero valent iron (nZVI) to sequester Ag(I) as Ag(0) nanostructures from aqueous solution. Batch experiments were performed with nZVI exposed to aqueous Ag(I) to investigate the effects of environmental parameters, including nZVI dose, temperature and pH. High temperature facilitates Ag(I) sequestration, and the rate constants are determined to be 0.02, 0.12, and 0.31 mg L/m"2 at 30, 50, and 60 °C, respectively. Ag(I) sequestration was adversely affected by adding nitric acid to the solution due to significant acid washing, decreasing the available nZVI active sites. Characterization techniques including TEM, XRD, and HR-XPS revealed that nZVI is oxidized to lepidocrocite and magnetite/maghemite and confirmed the formation of nanocrystalline silver. HR-XPS analysis indicated that Ag_2O forms rapidly as an intermediate due to Ag(I) adsorption onto the FeOOH layer. The Ag(0) nanostructures that are formed are fractal, spherical, and dendritic or rod-like, respectively, in morphology by FE-TEM images at different Ag/Fe mass ratios. A general reaction model for the interaction Ag(I) with nZVI is proposed. Our results suggest that nZVI is effective for Ag(I) removal

[en] Highlights: ► Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure. ► The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was key controlling factor. ► The threshold of the SCOD/TAN ratio was 2.4 at an influent pH of 8.5–9. - Abstract: The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700 m³ chicken-manure continuous stirred tank reactor (CSTR). A 12.3 L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35 ± 1 °C was employed for the investigation. With a corresponding organic loading rate of 1.5–3.5 kg-COD/m³ d over a hydraulic retention time of 1.5 d, a maximum volumetric biogas production rate of 1.2 m³/m³ d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250 mg/L) at an influent pH of 8.5–9.