Xingtai University

Liu K., Ren W., Ran C., Zhou R., Tang W., Zhou R., Yang Z., Ostrikov K.(.

Abstract Plasma-activated water (PAW) represents a promising green antibacterial agent for biomedical and agricultural applications. In this study, a novel AC multi-needle-to-water discharge device was developed to investigate the effects of gas flow on the generation and chemical composition of PAW. It is shown that the concentrations of NO 3 − and N(III) ( NO 2 − and HN O 2 ) in the PAW both increased with an extension of the plasma-processing time and a reduction of the gas-flow rate. The absorption of gas-phase products carried by the gas flow from the discharge chamber was found to be beneficial for the generation of both NO 3 − and N(III) in the PAW at a gas flow rate of 20–60 L h−1, yet their concentrations were still lower than those without any feeding gas. As opposed to NO 3 − or N(III), the H 2 O 2 concentration in the plasma-activated phosphate buffer solution (PAPBS) increased under stronger gas flows and was almost unaffected by absorption in PAPBS. The pH value of PAW increased at higher gas flow rates. A comparison of the N(III) in PAW and PAPBS reflects the effects of the reactions of NO 2 − and H 2 O 2 in the two different working liquids. To quantify the effects of gas flow on the discharge characteristics, gas temperatures were calculated from the optical emission spectra and were proven to be flow-independent near the discharge channel. Fourier transform infrared (FTIR) measurements of the gaseous products during the discharge, and further analysis of possible reaction pathways indicated that by controlling the gas flow in the multi-needle-to-water discharge system, the concentration of long-lived species in PAW could be tuned, which might favor the generation of ONOOH . These findings contribute to a better understanding of effective electric discharge-related mechanisms for enhancing the biochemical and chemical activities of PAW.

Zhao Z., Liang B., Wang M., Yang Q., Su M., Liang S.

• MON-OH-C was prepared via the carbonization of a novel MON-OH. • The adsorption capacity of MON-OH-C for FLU was 279.8 mg·g −1 . • The dynamic adsorption capacity of SPE was 180.1 mg·g −1 . • The π-π interaction and hydrogen bonding dominate the good adsorption. • MON-OH-C possesses great application potentials in adsorption fields. Flumequine (FLU) is a kind of fluoroquinolone antibiotics and has become a concerned pollutant as following widespread use of antibiotics and abuse to some extends. In this study, a microporous carbon derived from hydroxyl functionalized organic network (MON-OH-C) was prepared via the carbonization of a new member of MON-OH under nitrogen atmosphere at 500 °C. The adsorption kinetics, isotherm, thermodynamics and influence factors of pH, ionic strength, and humic acid on MON-OH-C for FLU adsorption were investigated in detail. The regeneration, reusability, application potentials and adsorption mechanism were further discussed. The adsorption of FLU on MON-OH-C accorded with the pseudo-second-order kinetic and Sips adsorption models. Rely on the interaction of π - π and hydrogen bonding between FLU and MON-OH-C, the maximum adsorption capacity for FLU under the static and solid phase extraction (SPE) dynamic conditions were 279.8 and 180.1 mg·g −1 , which were higher than many other reported adsorbents. MON-OH-C can be anticipated as a powerful adsorbent owing to its large surface area, physical and chemical stability, good water dispersibility, high adsorption and regeneration capability. It has great application potentials in adsorption removal, SPE sample pretreatment, and fix bed column. This work promoted the development of new synthesis strategy and the extensive application of pollutant removals by MON-OH-C in environmental science.

Ji J., Tang Z., Zhang W., Liu W., Jin B., Xi X., Wang F., Zhang R., Guo B., Xu Z., Shifaw E., Xiong Y., Wang J., Xu S., Wang Z.

Evaluating and exploring regional eco-environmental quality (EEQ), economic development equality (EDE) and the coupling coordination degree (CCD) at multiple scales is important for realizing regional sustainable development goals. The CCD can reflect both the development level and the interaction relationship of two or more systems. However, relevant previous studies have ignored non-statistical data, lacked multiscale analyses, misused the coupling coordination degree model or have not sufficiently considered economic development equality. In response to these problems, this study integrated multisource remote sensing datasets to calculate and analyse the remote sensing ecological index (RSEI) and then used nighttime light data and population density data to calculate the proposed nighttime difference index (NTDI). Next, a modified coupling coordination degree (MCCD) index was proposed to analyse the MCCD between EEQ and EDE. Then, spatiotemporal and multiscale analyses at the county, city, province, urban agglomeration and country levels were performed. Global and local spatial autocorrelation and trend analyses were performed to evaluate the spatial aggregation degree and change trends from 2001 to 2020. The main conclusions are as follows: (1) The EEQ of China displayed a fluctuating upwards trend (0.0048 a−1), with average RSEI values of 0.5950, 0.6277, 0.6164, 0.6311 and 0.6173; the EDE of China showed an upwards trend (0.0298 a−1), with average NTDI values of 0.1271, 0.1635, 0.1642, 0.2181 and 0.2490; and China’s MCCD indicated an upwards trend (0.0220 a−1), with values of 0.4614, 0.5027, 0.4978, 0.5401 and 0.5525. (2) The highest global Moran’s I of NTDI and MCCD was achieved at the city scale, while the highest RSEI was achieved at the county scale. From 2001 to 2020, the spatial agglomeration effect of the RSEI decreased, while that of the NTDI and MCCD increased. (3) A power function relationship occurred between NTDI and MCCD at different scales. Furthermore, the NTDI had a higher contribution to improving the MCCD than the RSEI and the R2 of the fitted curve at different scales ranged from 0.8183 to 0.9915.

Zhao Z., Zhao J., Wang H., Li X., Yang L., Zhao Z., Liu X., Liu Y., Liu P., Cai Z.

Finding a suitable replacement for the high potential of anodic water electrolysis (oxygen evolution reaction (OER)) is significant for hydrogen energy storage and conversion. In this work, a simple and scalable method synthesizes a structurally unique Ni3N nanoarray on Ni foam, Ni3N-350/NF, that provides efficient electrocatalysis for the urea oxidation reaction (UOR) that transports 10 mA cm−2 at a low potential of 1.34 V. In addition, Ni3N-350/NF exhibits electro-defense electrocatalytic performance for hydrogen evolution reaction, which provides a low overpotential of 128 mV at 10 mA cm−2. As proof of concept, all-water-urea electrolysis measurement is carried out in 1 M KOH with 0.5 M Urea with Ni3N-350/NF as cathode and anode respectively. Ni3N-350/NF||Ni3N-350/NF electrode can provide 100 mA cm−2 at a voltage of only 1.51 V, 160 mV less than that of water electrolysis, which proves its commercial viability in energy-saving hydrogen production.

Xu Y., Wang Y., Zhong Y., Lei G., Li Z., Zhang J., Zhang T.

On the basis of hypergolic dicyandiamide (DCA) and cyanoborohydride (CBH) anions, 1-methyl-1,2,4-triazole (MTZ) ligand, and transition metal (Co/Ni/Cu) cations, five hypergolic coordination compoun...

Xiao P., Gong Y., Li D., Li Z.

Graphitization (1400 °C–2200 °C) of polyacrylonitrile (PAN)-based carbon fiber in a small furnace with direct electric heating by Joule effect was studied in situ by small angle X-ray scattering (SAXS) with X-ray synchrotron radiation. The two-dimensional SAXS images display an anisotropic shape indicating the existence of needle-like or elongated ellipsoid-shaped pores oriented along the fiber axis. The one-dimensional scattering curves display obvious positive deviation from Porod's law indicating the existence of micro-fluctuation of electron density in the skeleton of the fiber which give rise to additional scattering. After correcting the deviation from Porod's law, the pure pore scattering was derived, and the pore structure parameters were computed. The results show that with increasing temperature the orientation angle decreases whereas the orientation degree increases. The long axis decreases whereas the short axis increases leading to a lower axial ratio. The size distribution becomes broader and there is a maximum value of porosity and specific surface area at 1900 °C. The change of pore structure in the fiber with temperatures can be approximately divided into two stages corresponding to denitrification condensation (1400 °C–1900 °C) and structure rearrangement (1900 °C–2200 °C) during graphitization, respectively. The corresponding mechanism was analyzed. Reciprocal relationship between the orientation of the needle-like or elongated ellipsoid-shaped pores in carbon fiber and the scattering images (inspired from Macromolecules, 2000, 33, 1848–1852; Polymer, 2001, 42, 1601–1612; Journal of Light Scattering (In Chinese), 2021, 33, 328–334). The left is schematic diagram and the right is actual sample and SAXS images. Where φ is the orientation angle of pore, L is the long axis of pore, r is the short axis of pore, q 12 and q 3 are the components of the reciprocal space vector q (q = 4π·sinθ/λ, 2θ is the scattering angle, λ is the incident X-ray wavelength) in the directions perpendicular and parallel to the principal axis of the pore, respectively. • In-situ SAXS study on PAN-based carbon fiber during graphitization (1400 °C–2200 °C). • Obvious positive deviation from Porod's law for all measured SAXS curves. • Change of pore structure of fiber in two stages dividing by 1900 °C.

Yan Z., Sun Z., Xia A., Yin R., Huang X., Yue K., Xu H., Zhao G., Qian L.

Novel Li3VO4/carbon sheets (LVO/CS) composites from cellulose were first prepared by simple freeze-drying and hydrothermal methods as a high-performance anode material for lithium-ion batteries (LIBs), realizing the combination of biomass carbon materials and Li3VO4. Elemental composition and microstructures of the LVO/CS composites were characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and so on. Meanwhile, electrochemical performances were investigated by battery testing system and electrochemical workstation. Furthermore, the impact of the mass ratio of LVO and CS on battery performances was researched, and it was found that the LVO/CS-2.0 (mass ration of LVO:CS was 24:1) composites exhibited excellent performances. The specific capacity of LVO/CS-2.0 reached up to 716 mAh g-1 after 100 cycles at low current density 0.1 A g-1, which was better than those of LVO matrix materials such as LVO/carbon nanotubes, LVO/carbon nanofibers and LVO/N-doped graphene. Considering its advantages, our proposed technique can be used to fabricate other composites based on carbon materials from cellulose for LIBs.

Xie F., Li Z., Wang W., Li D., Li Z., Lv B., Hou B.

Carbonization can enhance the utilization of coal. Pore structure is the main feature of the physical structure of coal and its carbonization products as char and coke. In this work, we performed an in-situ small angle X-ray scattering (SAXS) study on high temperature carbonization (1200 °C) of a kind of lignite and a kind of sub-bituminous coal. The variation of pore structure including pore size distribution, porosity and specific surface area of coal illustrates the different stages of the carbonization process.

Xu Y., Wang Y., Zhong Y., Lei G., Li Z., Zhang J., Zhang T.

In this study, a hypergolic linker (dicyanamide, DCA) and a high-energy nitrogen-rich ligand (1,5-diaminotetrazole, DAT) were applied to construct high-energy metal-organic frameworks (HEMOFs) with hypergolic property. Three novel metal-organic frameworks (MOFs) were synthesized via a mild method with fascinating 2D polymeric architectures, and they could ignite spontaneously upon contact with white fuming nitric acid (WFNA). The gravimetric energy densities of the three HEMOFs all exceeded 26.2 kJ·g-1. The cupric MOF exhibits the highest gravimetric and volumetric energy density of 27.5 kJ·g-1 and 51.3 kJ·cm-3, respectively. By adjusting the metal cations, high-energy ligands and hypergolic linkers can improve the performance of hypergolic MOFs. This work provides a strategy for manufacturing MOFs as potential high-energy hypergolic fuels.

Zhao T., Ma X., Cai H., Ma Z., Liang H.

A series of the magnetic CuFe2O4-loaded corncob biochar (CuFe2O4@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe2O4@CCBC and the pristine corncob biochar (CCBC) were characterized using XRD, SEM, VSM, BET, as well as pHZPC measurements. The results revealed that CuFe2O4 had a face-centered cubic crystalline phase and was homogeneously coated on the surface of CCBC. The as-prepared CuFe2O4@CCBC(5%) demonstrated a specific surface area of 74.98 m2·g−1, saturation magnetization of 5.75 emu·g−1 and pHZPC of 7.0. The adsorption dynamics and thermodynamic behavior of Pb(II) on CuFe2O4@CCBC and CCBC were investigated. The findings indicated that the pseudo-second kinetic and Langmuir equations suitably fitted the Pb(II) adsorption by CuFe2O4@CCBC or CCBC. At 30 °C and pH = 5.0, CuFe2O4@CCBC(5%) displayed an excellent performance in terms of the process rate and adsorption capacity towards Pb(II), for which the theoretical rate constant (k2) and maximum adsorption capacity (qm) were 7.68 × 10−3 g·mg−1··min−1 and 132.10 mg·g−1 separately, which were obviously higher than those of CCBC (4.38 × 10−3 g·mg−1·min−1 and 15.66 mg·g−1). The thermodynamic analyses exhibited that the adsorption reaction of the materials was endothermic and entropy-driven. The XPS and FTIR results revealed that the removal mechanism could be mainly attributed to the replacement of Pb2+ for H+ in Fe/Cu–OH and –COOH to form the inner surface complexes. Overall, the magnetic CuFe2O4-loaded biochar presents a high potential for use as an eco-friendly adsorbent to eliminate the heavy metals from the wastewater streams.