Search

Aqueous zinc ion batteries (ZIBs) are widely researched due to the low-cost and intrinsic safety. However, the rate capability and specific capacity of ZIBs is limited due to the dissolution and structural collapse of cathode materials. It is crucial to construct stable cathode materials to promote rate capability and cycle stability of ZIBs. In this paper, The V3O7 was tightly attached to the surface of graphene oxide (GO) by a hydrothermal reaction and a V3O7/GO heterostructure was successfully achieved. The GO could increase structural stability, enhance electrical conductivity, and expand specific surface area of V3O7. Therefore, the V3O7/GO with a heterostructure exhibits an improved cycle stability and rate capability compared with V3O7. It displayed a specific capacity of 275.6 mA h g−1 at a current density of 1.0 A g−1. The study paves the way for promoting the Zn2+ storage performance of vanadium oxide and developing stable cathode materials of ZIBs.

Lithium-ion capacitors (LICs) can combine the high energy density of battery-type electrode and high power density of capacitor-type electrode, which is considered as one of the most promising electrochemical storage devices. The challenge of developing superior performance LICs is designing suitable electrode materials to overcome the kinetic imbalance between the battery-type anode and the capacitor-type cathode. Herein, defect-rich carbon encapsulated Fe3C nanoparticle (Fe3C@DRC) was obtained via a modified sol-gel method with a calcination process. The defect-rich and microporous structure effectively boosts kinetics and provides additional reaction sites for lithium-ion intercalation/deintercalation process, which leads to an excellent capacity (215 mAh g−1 at 1 A g−1 after 800 cycles) and rate capability (128.8 mAh g−1 even at 10 A g−1). Then a novel Fe3C@DRC//AC LIC was consisted using Fe3C@DRC as anode and activated carbon as cathode. The Fe3C@DRC//AC LIC demonstrates a wide potential window (0–4 V), delivers a high energy density of 187.8 Wh kg−1 at a power density of 200 W kg−1, reached a high power density of 4000 W kg−1 at an energy density of 80 Wh kg−1, and coupled with a reasonable life span (84.8% after 6000 cycles at a current density of 1 A g−1). The study indicates that the introduction of defect-rich strategy may push the practical application of high-rate and high-energy LIC anode materials in energy fields.

This paper introduces new seawater flocculants. Ferric sulfate solution and polysilicic acid were mixed. After standing and curing, polymeric ferric silicate sulfate was obtained. The optimum preparation process was explored. When Fe/Si=10:20, curing pH in the range of 1.0 to 3.0, flocculants had best flocculating activity. The polymeric ferric silicate sulfate solution and 200 μg/L chitosan solution were mixed to make composite flocculants. Flocculating activity assessments were studied. When pH in the range of 6.0 to 10.0, temperature in the range of 10 °Cto 40 °C, flocculating activity could be stable. Total phosphorus (TP) and total organic carbon (TOC) removal rates of new flocculants were higher than 80% while algae and bacteria removal rates of new flocculants were all higher than 90%. These flocculants were multi-effect seawater flocculants.

The modified diatomite was prepared by calcination and alkali washing, and the feasibility of using modified diatomite for enhanced coagulation treatment of slightly polluted seawater was investigated in this study. SEM and BET analysis showed that the raw diatomite contained impurities, which were removed after refined and purified treatment. The use of diatomite as a coagulant aid improved interparticle bridging thus incorporating the cells into flocs more efficiently, producing settleable flocs of greater density, size and strength. The enhanced coagulation with ferric sulfate and modified diatomite improved the removal efficiency of turbidity, ammonia nitrogen, total phosphorus and CODMn in seawater samples. At the optimal diatomite dosage of 60 mg/L and ferric sulfate dosage of 6 mg/L, the removal efficiency of turbidity, NH3-N, TP and CODMn reached 93.8%, 26.3%, 94.8% and 44.4% respectively. It has been proved that the enhanced coagulation through the ferric sulfate and modified diatomite, as coagulant aid and adsorbent, is more efficient and environmentally than using traditional metal coagulant only for treatment of slightly polluted seawater.

Muds and water samples collected from the Bohai Sea were selected to build seawater anaerobic ammonia oxidation reactor. The reaction volume was 18 L. The startup of reactor was divided into two stages. The first stage lasted five months and hydraulic retention time was 18L/7 d. The second stage lasted a month and hydraulic retention time was 18L/14 d. Ammonia and nitrite of influent and effluent were monitored. During the first stage, the removal rate of ammonia nitrogen was around 50% and the nitrite nitrogen increased by 50%. During the second stage, the removal rate of ammonia nitrogen reached more than 75% and the removal rate of nitrite nitrogen reached more than 90%. The removal ratio of ammonia nitrogen and nitrate nitrogen was about 1:1.17. These results suggested reactor start-up successful. Microbial community in reactor was monitored by polymerase chain reaction. Once the reactor started, specific bands of anaerobic ammonia oxidation microorganisms were found.

Magnesium borate (Mg2B2O5) whisker was successfully synthesized by high temperature flux method using Magnesium chloride, boric acid, sodium hydroxide and sodium chloride as raw materials.The as-prepared product was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy(SEM), Transmission Electron Microscope (TEM) and X-Ray Photoelectron Spectrometry (XPS). The results showed that the as-prepared sample had triclinic structure and consisted of whisker-like particles with an average diameter about 1.25 μm and length up to 40μm. XPS results confirmed that the molar ratio of each atom agreed with the stoichiometric composition of Mg2B2O5. The growth mechanism was briefly discussed.

Lithium extraction from seawater and brine is an important approach to solving the short supply of lithium resource. Development of ion-sieve adsorption materials is the key of realizing industrial application of lithium extraction from seawater and brine with high ratio of magnesium to lithium. Although the synthetic process is complicated, with plenty of influencing factors, levels, and large amounts of data, this research successfully optimized the synthesis conditions by orthogonal experiment and statistical analysis. The achievements will lay solid foundation for the development of lithium adsorption materials.

In this paper, several types of PVDF hollow fiber membranes used in the gas membrane separation process for extracting bromine from simulated seawater or concentrated seawater were studied. The micropore, hydrophobic property, mechanical strength and material chemistry of the PVDF membranes soaked in seawater or concentrated seawater were characterized by SEM-EDX, IR, contact angle testing instrument and electronic fabric strength tester, which were compared with those of origin membranes. At last, the mass transfer coefficient and flux during a long time were gained by operating a permeation experiment with a chosen type of PVDF membrane module.

A single inlet and multi-inlet hollow fiber modules (HFMs) were designed in order to investigate the fluid hydrodynamics of the shell side. Residence time distribution (RTD) curves was measured under different packing density and inlet. Mean residence time ( ), variance( ) and the number of tanks (N) were also calculated to reflect the degree of backmixing. The experimental results indicated that the random packing of fiber caused the non-ideal flow in shell side. With the increasing of the packing density, the non-ideal flow was more serious. Contrasting to the traditional one, multi-inlet hollow fiber modules could weaken the trailing of the RTD curves and control the backmixing. With the quantity and the site of the inlets changed, non-ideal flow can be further improved. The hydraulic characterization of the shell side flow were related with not only the quantity but also the site of inlets. The results indicated that the muti-inlets design is superior to that of a single inlet.