Structural characteristics and residual stresses in oxide films produced on Ti by pulsed unipolar plasma electrolytic oxidation

Oxide films, 7–10 µm thick, were produced on commercially pure titanium by plasma electrolytic oxidation in a sodium orthophosphate electrolyte using a pulsed unipolar current with frequency (f) and duty cycle (δ) varying within f = 0.1–10 kHz and δ = 0.8–0.2, respectively. The coatings comprised a mixture of an amorphous phase with nanocrystalline anatase and rutile phases, where the relative rutile content range was 17–25 wt%. Incorporation of phosphorus from the electrolyte into the coating in the form of PO₂ ^–, PO₃ ^2– and PO₄ ^3–, as demonstrated by EDX and FT-IR analyses, contributed to the formation of the amorphous phase. Residual stresses associated with the crystalline coating phase constituents were evaluated using the X-ray diffraction sin² ψ method. It was found that, depending on the treatment parameters, internal direct and shear stresses in anatase ranged from–205 (±17) to–431 (±27) MPa and from–98 (±6) to–145 (±10) MPa, respectively, whereas the rutile structure is comparatively stress-free.     

Ion-exchange resin decomposition in supercritical water

Abstract

Using supercritical water oxidation, the cation exchange resin was decomposed fast and completely to water, carbon dioxide and sulfuric acid. While the resin decomposition yield increased with the reaction time and the amount of hydrogen peroxide added as oxidizing agent, it was constant in the resin concentration from 0.14 to 1.9 dry resin weight percent to water. More than 99% of the cation exchange resin was decomposed with hydrogen peroxide added in the amount of 7 times the stoichiometric value at 673 K and 30MPa for 30 minutes of the reaction time. The cation exchange resin is decomposed through two main reaction pathways. One has a rate controlling intermediate such as acetic acid whose decomposition rate was very slow, and the other does not have stable intermediates. The decomposition of the acetic acid is a significant factor for the complete decomposition of the resin, although it does not dominate the whole resin decomposition. A simple kinetic model that estimates the resin decomposition yield was developed.     

二氧化钛紫外光在线消解测定COD的研究

以TiO2-K2Cr2O7协同光催化氧化体系为基础，结合流动注射分析方法建立了一种快速测定水样中化学需氧量（COD）的简便方法．该方法测试速度快，不需有毒、昂贵的试剂，具有广阔的应用前景．COD含量在10～100mg·L^-1和100～1000mg·L^-1范围内，吸光度与COD含量均呈良好的线性关系；测定30mg·L^-1和300mg·L^-1的COD标准溶液，RSD≤5．1％（n=7）；将本系统应用于实际环境水样测定，与国家标准分析方法测定结果相符．     

Recyclable gold nanoparticle catalyst for the aerobic alcohol oxidation and C-C bond forming reaction between primary alcohols and ketones under ambient conditions

A recyclable gold catalyst is synthesized from readily available reagents by immobilizing gold nanoparticles in aluminum oxyhydroxide support through a simple sol-gel method. The catalyst showed the high activity even at room temperature in the aerobic oxidation of various alcohols and in the coupling reaction between primary alcohols and ketones.     

A novel synthetic approach towards N-phenylsuccinimides from γ-lactam-2-carboxylic acid derivatives by reaction with CAN-NaBrO3

N-Arylsuccinimides have been synthesized by decarboxylative oxidation of N-aryl-γ-lactam-2-carboxylic acids with the dual oxidant CAN/NaBrO₃ in refluxing acetonitrile-water.     

纳米级ZnO/MgO固体的合成及其对CO的氧化活性

The ZnO/MgO solid samples containing the ZnO nanoparticles of controllable size were prepared using colloidal technique. The catalytic performance of the ZnO/MgO samples for the CO oxidation was measured. It was revealed that the rate of the CO oxidation reaction on the ZnO nanoparticles with variable average radius (2.01-2.29 nm) shows nonmonotonic dependence caused by the quantum-confinement effect.     

Cobalt-catalyzed aerobic oxidation of (E)- and (Z)-bishomoallylic alcohols

Stereoselectivity for (5-phenyltetrahydrofur-2-yl)alkan-1-ol formation (cis:trans < 1:99) from 5-methyl- and 5-phenyl-substituted 1-phenylpent-4-en-1-ols via cobalt-catalyzed aerobic oxidation was independent of the olefinic π-bond configuration of the substrates.     

Oxidation of isobutane over hydrothermally synthesized Mo-V-Te-Nb-O mixed oxide catalysts

MoV_0.3Te_0.17 and MoV_0.3Te_0.17Nb_0.12 catalysts were prepared by a hydrothermal synthesis route and tested for the oxidation of isobutane and isobutene. Characterization results showed that the structure and property of Mo-V-Te-based catalysts are relatively different depending on the presence of the Nb element. Catalytic tests showed that the selectivity of methacrolein can comparatively be improved by the addition of Nb into the MoV_0.3Te_0.17 catalyst for the selective oxidation of isobutane.