Symmetric Aqueous Batteries of Titanium Hexacyanoferrate in Na+, K+, and Mg2+ Media

Symmetric batteries, in which the same active material is used for the positive and the negative electrode, simplifying the manufacture process and reducing the fabrication cost, have attracted extensive interest for large-scale stationary energy storage. In this paper, we propose a symmetric battery based on titanium hexacyanoferrate (TiHCF) with two well-separated redox peaks of Fe3+/Fe2+ and Ti4+/Ti3+ and tested it in aqueous Na-ion/ K-ion/Mg-ion electrolytes. The result shows that all the symmetric batteries exhibit a voltage plateau centered at around 0.6 V, with discharge capacity around 30 mAhg−1 at C/5. Compared to a Mg-ion electrolyte, the TiHCF symmetric batteries in Na-ion and K-ion electrolytes have better stability. The calculated diffusion coefficient of Na+, K+, and Mg2+ are in the same order of magnitude, which indicates that the three-dimensional ionic channels and interstices in the lattice of TiHCF are large enough for an efficient Na+, K+ and Mg2+ insertion and extraction.

The rainfall effect onto solidification and stabilization of heavy metal-polluted sediments

Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient ( D e ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient ( D e ) for Cu was 1.28 × 10 1 cm 2 s –1 , indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients ( D i ) for Cd, Cu and Pb were 7.44 × 10 −11 , 8.18 × 10 −12 and 7.85 × 10 −12 cm 2 s –1 , respectively, indicating their relatively low mobility of heavy metal in S/S sediments.

Water Uptake Behavior of Lignin Modified Starch Film

A biodegradable urea crosslinked starch film was prepared. To improve the water resistance, the urea crosslinked starch system was reinforced with 5%, 10%, and 15% lignin. The prepared films were immersed in distilled water at three different temperatures, 25°C, 35°C and 45°C to study the behavior of water uptake. The addition of lignin effectively decreases water uptake as proven by lower water uptake equilibrium. Diffusion coefficient was calculated from the kinetic water uptake profile using the slope method of Fick’s second law for thin slab model. The calculated diffusion coefficient decreases as the lignin is increased. The diffusion coefficient is found to be dependent on the temperature. As more lignin is added to the system, higher activation energy is obtained due to the hydrophobicity of lignin.

Composition Control of Palladium-Sliver Alloy for Optical Fiber Hydrogen Sensor

The present work investigates diffusivity of hydrogen (H) in palladium-silver (Pd/Ag) over 300～1100K temperature range for Pd100-xAgx, X=0%～40% by using the Sievert Law. The silver in the Pd/Ag alloy has significantly higher diffusion as compared to pure Pd for hydrogen sensor, the addition of Ag reduces the critical temperature of α→Β phase transformations and also increases the solubility of H, and provides longer operational lifetime for hydrogen sensor. It was found that the diffusion coefficient of H in Pd/Ag alloy decreases with increasing Ag and with increasing temperature, the calculated diffusion coefficient of H in the Pd/Ag alloys were found to have a maximum at 24%～25% Ag.

Ferrous Ion Oxidation Behavior on a Bacteria Attached Power Micro Electrode

In this paper a special At.f (Acidthiobacillus ferrooxidans) modified carbon powder microelectrode was prepared, and a series of electrochemical measurements were conducted to study ferrous ion Fe2 + oxidation mechanism on the electrode. CV (cyclic voltammetry) studies show that this oxidation reaction is reversible when c (Fe2 +) is lower than 0.16mol/L. At higher speed scanning, the currents through the electrode include two parts of the micro disc current and the thin layer current, while at lower speed scanning of steady state process the current provided by thin layer could be ignored, the whole oxidation reaction was controlled by diffusion process, and the calculated diffusion coefficient D0 is about 6. 25 ×10 - 6cm2.s – 1. The transient potential stair step studies also have been conducted. The results are consistence with steady state ones although thin layer currents should be taken in to account.