Study on the anodic film formation process of AZ91D magnesium alloy

The formation of anodic film of AZ91D magnesium alloy has been investigated by means of electrochemical impedance spectroscopy (EIS), cyclic voltammetry, anodic polarization curve, current-time transients and SEM technique. The results show that, under our experimental conditions, the formation of AZ91D anodic film follows the mechanism of 3D nucleation with diffusion controlled growth. With the increase of applied anodizing potential, the nucleation type of anodic film changes from progressive to instantaneous. The results also show that the initially formed anodized film is threadlike and porous, and high potential is essential for the formation of good anodic film with excellent properties.     

Adsorption of dissolved organics from industrial effluents on to activated carbon

Industrial effluents usually include multicomponent organic solutes. The optimum pH for adsorption of a specific industrial effluent on activated carbon should be determined experimentally because, in general, more than one mechanism is involved. A series of experiments was conducted to establish the influence of the initial hydrogen ion concentration on carbon adsorption of organic solutes. For these studies, powdered activated carbon was used, and the water systems studied included both single component pure organic compounds as well as multicomponent organic wastes. Results indicate that the pH effect upon the effectiveness of carbon adsorption mainly depends upon the nature of the adsorbed substance. In general, the degree of ionisation is the controlling factor for adsorption of ionic organic solutes on activated carbon. Adsorption reaches a maximum at the point of least ionisation of the adsorbate. As the organic compounds become more complex (i.e. longer hydrocarbon chains, higher molecular weights, increased branching), the electrical adsorption forces between activated carbon and ionic organic solutes will govern. Anionic surfactants meet with decreased electronegative repulsive forces at low pH levels, which increase the effectiveness of carbon adsorption. However, the adsorption of a cationic surfactant is increased by an increase in the electronegative carbon surface at high pH levels. When ionic organic solutes become much more complex, like a polymer, the effects of both ionisation and electrical adsorption forces become less important. Instead, the adsorption rate will be controlled by the extent of hydrolysis caused by the pH adjustment. For non-ionic organic solutes, chemical reaction(s) between the adsorbate and the added chemical (acid or base) for pH adjustment is an important controlling factor. Again, hydrolysis is responsible for the breakdown of larger size molecules to smaller sizes. Then an increase in adsorption rate with decreasing molecular weight of adsorbate is expected.     

Mineral nutrition of slash pine in subtropical Australia. II. foliar nutrient response to fertilization

In the previous paper, we reported the stand growth of slash pine (Pinus elliottii) during the first 11.5 years of plantation in response to (1) initial fertilization at plantation establishment with P rates of 11, 22, 45 and 90 kg P ha^–1 which were either banded or broadcast in the presence or absence of basal fertilizers containing 50 kg N ha^–1, 50 kg K ha^–1 and 5 kg Cu ha^–1 and (2) application of additional 40 kg P ha^–1 at age 10 years. Here we present the responses in foliar nutrient concentrations of slash pine in the first 11.5 years to the initial fertilization and the additional P applied at age 10 years.Foliar N and K concentrations in the first 9.6 years of plantation decreased with the initial P rate. Application of the basal fertilizers improved foliar Cu concentration. Foliar Ca and Mg concentrations increased linearly with the initial P rate. The initial fertilization did not affect foliar Mn concentration in the first 9.6 years. Foliar P concentration increased quadratically with the initial P rate, which accounted for 77–86% of the variation in foliar P concentration. Most of the explained variation in foliar nutrient concentrations was attributable to the plantation age except for foliar P concentration. In the case of foliar P concentration, 53% was explained by the initial P rate, 31% by the plantation age and 2% by the positive interaction between the initial P rate and the plantation age. Foliar P concentration of slash pine at age 11.5 years increased quadratically with the initial P rate and linearly with the additional 40 kg P ha^–1 applied at age 10 years, accounting for 81% of the variation in the foliar P concentration. Foliar nutrient analysis indicated that P was the major limiting nutrient affecting the stand growth of slash pine in the first 11.5 years.     

Reactant induced restructuring and corrosion of germanium-palladium catalysts during hydrogenation reactions

An anomalous rate enhancement with increasing conversion has been observed during the liquid phase hydrogenation of nitrobenzene and crotonaldehyde over Ge/Pd/C catalysts at ambient temperature and atmospheric pressure. Inductive coupled plasma atomic emission spectroscopy and electrochemical measurement of the oxidation state of catalysts during reaction revealed that the bimetallic particles were partially oxidized by the reactants, which resulted in Ge-dissolution and increased exposure of Pd on the surface. It is proposed that the surface and bulk composition of Ge/Pd catalysts are a function of their oxidation state. This behaviour is due to the unusually high mobility of Ge in the Pd lattice and to the good solubility of GeO₂ in polar solvents. The influence of hydrogen transport on the corrosion process and the stability of other X/Pd type bimetallic catalysts during liquid phase hydrogenation are also discussed.     

大分子表面改性剂在聚合物表面的富集行为

简述了大分子表面改性剂添加到聚烯烃基体中时接触介质的诱导作用和聚烯烃基体结晶的异质排斥作用及其相对分子质量、链节的柔顺性和与基体的相容性对其表面富集的影响。提出大分子表面改性剂设计合成的基本原则:化学结构和使用环境相匹配、憎水基功能团和亲水基功能团相适应、使用效率和功能持久性相平衡。介绍了大分子表面改性剂合成的主要方法。     

氧化沟模型处理亚麻沤制废水的研究

利用液可清(ACF32)培养污泥,水解酸化、氧化沟工艺进行亚麻沤制废水处理。结果表明,该系统处理高浓度有机废水效果良好,COD去除率可达95%-97%,TN去除率可达78%-82%,TP去除率可达78%-86%。     

Hydrosilylation and dehydrocondensation reactions of methylhydridesiloxane to acrylic and methacrylic acids

The hydrosilylation of α,ω‐bis(trimethylsiloxy) methylhydridesiloxane (degree of polymerization ≈ 53) with acrylic and methacrylic acid with various ratios of the initial compounds, in the presence of platinum hydrochloric acid, has been investigated. In the presence of platinum hydrochloric acid, competitive dehydrocondensation reactions take place with the formation of various oligomers with various chemical links. In the later stages of the reaction, three‐dimensional systems have been obtained. During dehydrocondensation, the reaction order, reaction rate constants, and activation energy have been determined. The structures of the synthesized oligomers have been determined with IR and NMR spectroscopy data. Gel permeation chromatography, differential scanning calorimetry, and X‐ray analyses of the synthesized oligomers have been carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3243–3252, 2007     

排气挤出机分流环结构与产量平衡问题的研究

挤出波动和冒料是限制排气挤出机使用的2个重要因索。在橡胶排气螺杆第1计量段的末端加入分流环，并采用Polyflow软件对其流场进行分析；研究同一根螺杆在不同的工艺参数下二阶螺杆的流量平衡与分流环结构的关系。     

Electropolymerization of chlorinated phenols on a Pt electrode in alkaline solution. Part II: An electrochemical quartz crystal microbalance study

Electropolymerization of phenol and mono-, di-, tri-, pentachlorophenols was studied using EQCM on a Pt electrode at 0.78 V (SHE) in 1 M NaOH solution containing 0.1 M of the corresponding phenol. The highest electropolymerization rate was found for ortho-substituted chlorophenols indicating a weak fouling of the electrode. Low electropolymerization rates for para-substituted chlorophenols suggest a low permeability of the polymer film, resulting in rapid electrode fouling. The EQCM data suggest that electropolymerization of chlorophenols occurs without Cl-elimination for the monomers with unsubstituted ortho and para positions. Dechlorination is most pronounced for electropolymerization of para-substituted isomers. The mechanism of electropolymerization of chlorophenols is discussed.     

聚乙烯转光棚膜的加工及应用研究

本文对聚乙烯转光棚膜的加工和光转换剂的作用、配比关系及物理性能进行了讨论。