由氯乙酸废母液制备乙二酸钠和羟基乙酸钠的探讨

本文主要介绍以生产氯乙酸的废母液为原料,制备乙二酸钠和羟基乙酸钠的实验,并对反应机理、最佳反应条件进行了探讨。

连续法生产草酸钠工业化试验

采用高温气体作热载体，在脱氢塔内将固体甲酸钠连续脱氢反应生产草酸钠。工业试验结果表明甲酸钠受热均匀、脱氢反应完全。

高相对分子质量甲壳素、壳聚糖的制备

采用红外光谱分析甲壳素、壳聚糖的主要性能指标 ,研究了EDTA和HCl用于制备甲壳素的脱钙工艺 ,其结果为 :EDTA可替代HCl用于制备甲壳素的脱钙工艺 ,特别是由于其所特有的脱钙机理 ,脱钙时对甲壳素碳骨架基本无损伤 ,因此其产品的分子质量较HCl法的大 ,在同等条件下 ,可制得高相对分子质量的甲壳素和壳聚糖。其它性能指标如产率 ,脱乙酰度 ,颜色等均优于采用HCl法制得的产品。此外 ,EDTA法还可减少环境污染 ,而不增加成本。

胭脂红酸褪色光度法检测H_2O_2-Fe^(2+)产生的羟自由基

提出了Fe2+ H2O2 胭脂红酸分析新体系,并用于羟自由基的测定。该法用Fenton反应产生羟自由基,并加入胭脂红酸显色剂,使胭脂红酸褪色,采用分光光度计测定其ΔA值的变化,可间接测定羟自由基的产生量。通过测定条件的研究,得出最佳实验条件,并对抗坏血酸等7种抗氧化剂的抗羟自由基氧化性能进行了比较。

Extraction of metals from a zinc smelting slag using two-step procedure combining acid and ethylene diaminetetraacetic acid disodium

A two-step leaching method in combination of acid and ethylene diaminetetraacetic acid disodium （EDTA-Na2） was applied to extract metals such as Cd, Cu, Fe, Pb and Zn from a zinc smelting slag. The results show that the extraction rates of Cd, Cu, Fe and Zn in slag reach 88.3%, 54.1%, 69.6% and 54.7%, respectively, while the extraction rate of Pb is only 0.05% leached with 1.25 mol/L sulfuric acid under the conditions of the ratio of slag to liquid of 100 g/L, 65 ℃ and 120 r/min for 2 h. However, Pb extraction rate from 1.25 mol/L sulfuric acid leached residue reaches as high as 66.5% by using 0.1 mol/L EDTA-Na2 solution. The results indicate that two-step sequential extraction procedure combining 1.25 mol/L sulfuric acid and 0.1 mol/L EDTA-Na2 solution can extensively extract Cd, Cu, Fe, Pb and Zn from zinc smelting slag.

Intestinal preparation prior to capsule endoscopy administration

In order to have an adequate view of the whole small intestine during capsule endoscopy, the preparation recommended consists of a clear liquid diet and an overnight fast. However, visualization of the small bowel during video capsule endoscopy can be impaired by intestinal contents. To improve mucosal visualization, some authors have evaluated different regimens of preparation. There is no consensus about the necessity of intestinal preparation for capsule endoscopy and it should be interesting to develop adequate guidelines to improve its efficacy and tolerability. Moreover, the effect of preparation type (purgative) on intestinal transit time is not clear. Since a bowel preparation cannot defini-tively improve its visibility (and theoretically the yield of the test), it is not routinely recommended.

Effect of Additive EDTA on Crystallization Process of Magnesium Hydroxide Precipitation

The effects of additive ethylenediaminetetraacetic acid (EDTA) on crystallization process were investigated by the induction time of MgSO 4-NaOH system. Nucleation and growth rates, growth mechanism and particle size distribution of magnesium hydroxide precipitation were involved with. The induction time in unseeded and seeded precipitation of magnesium hydroxide with and without additive EDTA was measured. The conductivity method was used to determine the induction period. Theoretical relations of the induction time and supersaturation ratio for different growth mechanisms and a combined analysis on the induction time were applied to determine nucleation and growth rates. The growth mechanism of magnesium hydroxide precipitation was disclosed by analyzing the experimental data with and without additive. The analysis on induction time indicated that additive EDTA had a significant influence on both nucleation and growth of magnesium hydroxide precipitation. The mechanism underlying the effect of EDTA on crystal growth was 2-dimension nucleation-mediated growth model.

Flue gas desulphurization using sodium sulfide on pilot scale

A novel technique of flue gas desulphufization （FGD） using industrial sodium sulfide as absorbent is described to remove SO2 in flue gas. The FGD byproduct in this novel technique is sodium thiosuffate （Na2S2O3 · 5H2O, Hypo） which can be used as chemical raw material. Optimal operating parameters about this technique have been determined. In order to enhance productive efficiency of sodium thiosulfate, EDTA disodium additive is added into absorption solution to prevent oxidation of sodium thiosulfate. Its optimal concentration is 0. 02 wt. %. The pH value of absorption solution is set in the range of 5 ~ 6.5. Experimental results show that SO2removal efficiency averagely reach 98.72 %. The highest productive efficiency of sodium thiosulfate reaches 83.24 %. The sodium thiosulfate formed during FGD can be separated from saturated absorbent by filtration, concentration and crystallization. The filtrate after separating sodium thiosulfate will be reused as SO2 absorbent by replenishing some fresh sodium sulfide.

Removal of As and Heavy Metals （Cd, Cu and Pb） in Fine Soil from Soil Washing Process Using Chelating Agent

Fine soil generated from the soil washing process can be the second problem, as contaminants are concentrated in the fine soil, and also took the difficult forms to treat because soluble and exchangeable fractions are already removed by soil washing process; therefore, the fine soil is indicated to hazardous waste, and discarded in hazardous waste landfill. Thus, this research would be performed that arsenic and heavy metals formed difficult to remove in the fine soil were converted to more treatable fractions with chelating agents. Moreover, feasibility study to apply the second remediation targeted to the fine soil inquired. As a result, the chelating agent was decided 50 mM Na2EDTA, and it could develop the complex. In addition, the result of sequential extraction showed that Mn/Fe-oxide fraction, comprised about 28% of amount at first, was decreased about 16%, and organic fraction, consisted approximately 20%, was also decreased about 11%, while exchangeable fraction and carbonate fraction were increased. This result means that the difficult fractions removed could change fractions） by chelating agent. This research can provide the possibility hazardous waste because of difficulty to remediate. the more treatable fractions （exchangeable and carbonate to treat the fine soil, although the fine soil was regarded to

残缺四氮杂卟啉的合成及其表征

以镁离子为模板,2,3-二丁硫基马来二腈为前躯体,采用模板法成功合成了全对称八正丁硫基四氮杂卟啉及其相关残缺四氮杂卟啉产物,相关化合物的结构用紫外光谱、质谱和核磁对其进行了表征。实验过程表明,相关化合物均呈现良好的溶解性,能很好的溶于常见有机溶剂,并且具有耐酸、耐高温等优点。

Electrode process of diethyldithiocarbamate on surface of pyrrhotite

The electrode process of diethyldithiocarbamate on the surface of pyrrhotite was studied using systematic electrochemical analysis, including cyclic voltammetry, chronopotentiometry and galvanostatic. Experimental results show that tetraethylthioram disulphide（TETD） is electrodeposited on pyrrhotite electrode surface in the presence of 1.0×10^-4 mol/L diethyldithiocarbamate when the electrode potential is higher than 0.25 V. The electrochemical kinetics parameters of the electrode process of diethyldithiocarbamate on surface of pyrrhotite are calculated as follows： the exchange current density is 2.48μA/cm^2 , and the transmission coefficient is 0.46. The electrodeposition includes two steps electrochemical reaction. The first reaction is electrochemical adsorption of diethyldithiocarbamatc ion, then the adsorbed ion associates with a diethyldithiocarbamate ion from the solution and forms tetraethylthioram disulphide on the surface of pyrrhotite.

Catalytic synthesis of diethyl carbonate with supported Pd-Cu bimetallic nanoparticle catalysts:Cu(Ⅰ) as the active species

Cupric oxide （CuO） and copper-cuprous oxide （Cu-Cu2O） nanoparticles were prepared by a simple hydrothermal method for the synthesis of diethyi carbonate （DEC） from ethanol. During these syntheses, varying NaOH and glucose concentrations were applied to explore and pinpoint the active species. It was found that PdCl2/CuO and PdCI2/Cu-Cu2O both catalysts exhibited good thermal stability and morphology. The results of catalytic tests showed that the catalysts prepared with 5 mol/L NaOH show superior catalytic performances because of their lower extent of agglomeration. It is noteworthy that the PdC12/Cu-Cu2O catalysts were the most active, especially the PdCl2/Cu-Cu2O catalyst prepared with 10 mmol glucose and having a higher Cu2O concentration. In Pd（ll）-Cu（II） （PdCl2/CuO） catalysts, there is an induction period, during which Pd（II） is reduced to Pd（0）, that must occur prior to electron transfer between Pd and Cu, and this can slow the catalytic reaction. To further pinpoint the active species, PdCl2/Cu-Cu2O catalysts with different Cu2O contents were prepared by controlling the dosages of glucose. The maximum DEC yield obtained with these catalysts was 151.9 mg.g-1.h-1, corresponding to an ethanol conversion of 7.2% and 97.9% DEC selectivity on an ethanol basis. Therefore, it was concluded that Cu＋ was the active species in this catalytic system, possibly because a higher proportion of Cu＋ reduces the Pd2＋ concentration and limits the CO oxidation side reaction, thus increasing DEC selectivity. In addition, Cu＋ promotes electron transfer between Pd and Cu without an induction period, which could also promote the catalytic activity.

Electrochemical study on adsorption behavior of surfactants at β-2CaO·SiO2/NaAlO2 interface

β-2CaO＇SiO2 was obtained with analytical grade reagents. Polyethylene glycol （PEG）, sodium polyacrylate （PAAS） and their mixture were used to inhibit the decomposition of β-2CaO·SiO2 in sodium aluminate solution. The potential of solid-liquid interface and the adsorption mechanism were studied by the methods of Zeta potential measurement and XPS. The results indicate that PEG and PAAS have synergistic effect on the inhibition of secondary reaction. The inhibitory effect is the best when the volume ratio of PAAS to PEG is 1：1 and the total concentration is 12.5 mg/L. PAAS adsorbs on the surface of β-2CaO-SiO2 by the formation of --COOCa coordinate bond, and the negative charge enters into Stem layer, which results in the decrease of particle potential and the obvious change of binding energy of Ca 2p, Si 2p and O Is. PEG only physically adsorbs on the surface ofβ-2CaO·SiO2, and had little effect on particle potential and binding energy of Ca 2p, Si 2p and O Is.

涤纶染色改性剂SIPG合成研究

研究了以５－磺酸纳－间苯二甲酸二甲酯为原料进行酯交换反应合成５－磺酸钠－间苯二甲酸双乙二酯(ＳＩＰＧ),并讨论了催化剂、反应温度、配比等反应条件对产品质量的影响。通过优化工艺条件,合成的产品具有二甘醇含量低,低温条件下稳定性好的特点。

Using DGT to Assess Cadmium Bioavailability to Ryegrass as Influenced by Soil Properties

A generally accepted method for predicting the bioavailability and transfer of cadmium(Cd) from soil to plants has not yet been established. In this study, the diffusive gradients in thin films(DGT) and conventional extraction methods for metal fractions were used to investigate how effective these methods were at predicting Cd bioavailability to ryegrass(Lolium perenne) and to assess whether these holistic variables were independent of the soil property variables. The influences of soil properties on the predictive capabilities of the different methods were evaluated using multivariate statistics. The Cd concentrations in the shoots and roots of ryegrass correlated more closely with the effective Cd concentration measured by DGT(CE), compared with those with soil total Cd, pore water Cd, and ethylenediaminetetraacetic acid disodium salt(Na2EDTA)- and acetic acid(HOAc)-extractable Cd. When soil properties were included in a stepwise multiple linear regression, Cd transfer to L. perenne was negatively influenced by p H and positively influenced by organic matter(OM). The multivariate statistics showed that the adjusted correlation coefficients for the plots involving soil total Cd, pore water Cd, and Na2EDTA- and HOAc-extractable Cd had been significantly improved after considering the influences of soil properties, which suggested that these methods were p H and OM dependent. For CE, the relationship was p H independent or only dependent in strongly acidic soils. These results suggested that the main soil factors affecting bioavailability had the lowest impact on the DGT technique. Therefore, the DGT technique provided significant advantages over conventional methods when assessing Cd bioavailability.

Influence of surfactants on the morphology and photocatalytic activity of Bi_2WO_6 by hydrothermal synthesis

The flower-like microsphere Bi2WO6 with an average diameter of 2.5 μm is synthesized by a simple hydrothermal method in the presence of surfactant sodium dodecyl sulfate （SDS） or polyvinylpyrrolidone （PVP）. The crystalline phase, compositions, morphology, microstructure, surface area and band gap energy of the Bi2WO6 are characterized by X-ray diffraction, X-ray energy-dispersive spectrum, scanning electron microscopy, transmission electron microscopy and absorption spectra. It is found that surfactant has a significant influence on the microstructure and properties of the samples. The surfaetant SDS en- hances the surface area and photocatalytic activity of Bi2WO6, while the surfactant PVP has an opposite effect. Under Xe lamp irradiation, the Bi2WO6 sample prepared in the presence of SDS can degrade dye Rhodamine B （RhB） effectively.