Processes of Removing Zinc from Water using Zero-Valent Iron

Zero-valent iron has received considerable attention for its potential application in the removal of heavy metals from water. This paper considers the possibility of removal of zinc ions from water by causing precipitates to form on the surface of iron. The chemical states and the atomic concentrations of solids which have formed on the surface of zero-valent iron as well as the type of the deposited polycrystalline substances have been analyzed with the use of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The BET surface area, the pH at point of zero charge (pH(PZC)), the ORP of the solutions, and the pH and chemical concentrations in the solutions have also been measured. Furthermore, the paper also considers the possibility of release of zinc from the precipitates to demineralised water in changing physicochemical and chemical conditions. In a wide range of pH values, Zn(x)Fe(3 − x)O(4) (where x ≤ 1) was the main compound resulting from the removal of zinc in ionic form from water. In neutral and alkaline conditions, the adsorption occurred as an additional process

Preparation and characterization of poly(vinylidene fluoride) based composite electrolytes for electrochemical devices

PVdF-based separators are very promising materials in electrochemical energy storage systems but theysuffer from fairly poor mechanical properties. To overcome this drawback, composite PVdF separatorswere fabricated and characterized in electrolytes of Li-ion batteries and supercapacitors. MacroporousPVdF composite separators were prepared by phase inversion method using PA and PET, and non-woven cellulose as support layers. Ionic conductivity and thermomechanical analyses were performedusing electrolytes of Li-ion batteries and supercapacitors. The composite approach allowed a tremen-dous increase of the mechanical performances of the separator (between 340 and 750 MPa) comparedto the unreinforced PVdF separator (56 MPa), without compromising the ionic conductivities (up to15.6 mS cm-1)

Poly(vinylidene fluoride)-based macroporous separators for supercapacitors

International audienceMacroporous polymer separators based on poly(vinylidene fluoride) (PVdF) and several VdF copolymers were prepared by a phase inversion process using acetone as a solvent. The resulting macroporous separators were characterized in terms of morphology, swelling behaviour, thermal and mechanical properties and ionic conductivity. The PVdF separator had a highly porous structure (80%) and exhibited good mechanical properties. Once filled by a molar solution of tetraethylammonium tetrafluoroborate (TEABF4) in acetonitrile (AN) it provided enhanced conductivity (18 mS cm−1 at 25 °C) compared with commercial cellulose and Celgard™ separators

Crosslinking of poly(vinylene fluoride) separators by gamma-irradiation for electrochemical high power charge applications

Macroporous poly(vinylene fluoride) (PVdF) separators were prepared by phase inversion method and introduced to a gamma (γ) radiation with and without cross-linking agents. Triallyl isocyanurate (TAIC) and a macromonomer of ethylene oxide- propylene oxide (MEP) were used as a cross-linking agent. The resulting membranes were characterized in terms of thermal and mechanical properties. Ionic conductivities were determined in a molar solution of tetraethylammonium tetrafluoroborate (TEABF4) in acetonitrile (AN) and propylene carbonate (PC). Excellent mechanical properties (250 MPa at 25 °C) and conductivities (14 mS cm−1) were obtained for the cross-linked separator prepared with TAIC

Batch removal of aqueous Cu2+ ions using nanoparticles of zero-valent iron: A study of the capacity and mechanism of uptake

In this study, nZVI prepared by borohydride reduction was applied for the removal of Cu2+ ions under a variety of experimental conditions. The uptake experiments investigated the effects of initial concentration, contact time, pH, and repetitive loading on the extent of retardation of Cu2+ ions. Within the applied conditions, the sorbent demonstrated fast uptake kinetics and outstanding fixation abilities up to an initial Cu2+ concentration of 200.0 mg/L. Partitioning of Cu2+ ions between liquid and solid phases demonstrated an isotherm of L-type. Within the studied conditions, the capacity of uptake was found to be 250 mg of Cu2+ per g of nZVI. According to X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results, Cu2+ ions were sorbed primarily via a redox mechanism that resulted in the formation of Cu2O and Cu0. The contact of iron nanoparticles with aqueous media caused extensive formation of iron oxide. However, the material did not completely lose its removal capacity and was repeatedly applied at low concentrations for further uptake trials