Negative effects of dissolved organic compounds on settling performance of goethite in Bayer red mud

Goethite, a typical iron-containing monomineral in red mud, was synthesized under the simulated Bayer digestion condition during the alumina production. The effects of dissolved organic compounds including sodium formate, sodium acetate, sodium oxalate, sodium salicylate and disodium phthalate on the settling performance of goethite slurries were studied. The settling performance of the slurries was also investigated with the addition of self-made hydroxamated polyacrylamide flocculant (HCPAM). The adsorption mechanism of dissolved organic compounds on the goethite surfaces was studied by FT-IR and XPS, respectively. The results show that the addition of organic compounds lowers the settling performance of the slurries and a deterioration in settling performance is observed in the order of sodium oxalate > sodium salicylate (～ disodium phthalate) > sodium formate > sodium acetate. Moreover, HCPAM can efficiently eliminate the negative effects of sodium formate, sodium acetate and sodium oxalate on the settling performance of the goethite slurries, but it can only partially improve the settling performance of the goethite slurries containing sodium salicylate or disodium phthalate. FT-IR and XPS results show that these organic compounds are chemically adsorbed on the goethite surface.     

异丙酚对大鼠脊髓背角神经元TTX敏感型钠通道失活和去失活效应的影响

目的: 观察异丙酚对急性分离的大鼠脊髓背角神经元TTX敏感型钠通道电流的影响及相关机制。方法: 取出生后7d的雄性SD大鼠,击昏后断头取脊髓腰膨大部位,分离背角神经元,应用全细胞膜片钳记录模式记录钠电流。距离神经细胞100μm施加0.3～30 μmol/L不同浓度的异丙酚,应用-10mV(持续30ms)刺激电压诱发钠电流,求出异丙酚对钠电流的半效抑制浓度(IC₅₀)。观察异丙酚对钠通道失活效应的影响时,应用从-80mV至-20mV的预刺激电压(阶差为10mV,持续30ms),再应用0mV刺激电压(持续30ms)诱发钠电流产生,向神经细胞施加IC₅₀水平的异丙酚。观察异丙酚对钠通道去失活效应的影响时,应用-10mV的预刺激电压(持续30ms),再给予-10mV、持续30ms的刺激电压诱发钠电流产生,两刺激电压的间隔时间为2～24ms。结果: 异丙酚可浓度依赖性地抑制TTX敏感型钠电流,其IC₅₀为(5.35±0.25) μmol/L。钠通道失活实验中,预刺激电压在-60mV到-40mV范围内,IC₅₀水平的异丙酚可显著抑制由刺激电压(0mV)诱发的钠电流(P<0.05)。钠通道去失活实验中,两刺激的间隔时间在2～6ms之间时,IC₅₀水平的异丙酚可显著性抑制由刺激电压(-10mV)诱发的钠电流(P<0.01,P<0.05)。结论: 异丙酚可抑制大鼠脊髓背角电压依赖性钠通道电流,这一作用与促进钠通道的失活和抑制钠通道的去失活有关。     

Joint Adsorption of Oleic and Phenylanthranilic Acids at Passive Iron

Adsorption of sodium oleate and its formulation with sodium phenylanthranilate from a borate buffer (pH 7.36) at passive iron was studied by ellipsometry and IR spectroscopy. The adsorption isotherm of sodium oleate was classified and its adsorption constants were determined. It was shown that the isotherm of a mixture of sodium oleate with sodium phenylanthranilate is shifted to lower concentrations, which is characteristic of a higher adsorption energy. The concurrent adsorption of these compounds is not induced since neither component enhances the adsorption of the other. IR spectroscopic data showed that, adsorbing at the oxidized iron surface, sodium oleate causes the formation of new compounds.     

Effect of inhibiting additives on the electrochemical behavior of <Emphasis Type="Italic">AMg-6</Emphasis> alloy in aqueous potassium acetate solutions at elevated temperatures

The electrochemical behavior of AMg-6 aluminum alloy in an aqueous acetate solutions with additions of sodium hydrophosphate, sodium benzoate, and benzotriazol at enhanced (up to 70°C) temperatures is studied. It is found that the time-resistant protective layers are formed upon the introduction of small amounts of sodium hydrophosphate (≤1%) or a mixture of sodium hydrophosphate and benzotriazol (0.5% Na₂HPO4 + 0.2% BTA).     

环保型水处理剂腐植酸钠的缓蚀协同效应

通过动态旋转挂片实验，研究了水处理剂腐植酸钠(HA-Na)的缓蚀性能以及与Zn^2 和葡萄糖酸钠复配的缓蚀协同效应。结果表明：HA-Na对碳钢有一定的缓蚀作用；与Zn^2 复配有较好的协同效应，而与葡萄糖酸钠复配没有协同效应；但是，HA-Na，Zn^2 和葡萄糖酸钠三者复配表现出优异的缓蚀性能。还探讨了HA-Na的缓蚀作用机理。     

304 不锈钢在氯化钠介质中点蚀缓蚀剂的研究

目的研究钼酸钠、葡萄糖酸钠及其复配物在氯化钠介质中,对304不锈钢点蚀的缓蚀作用。方法对钼酸钠、葡萄糖酸钠按不同配比进行复配得到不同缓蚀剂,采用极化曲线法分别测试在这几种缓蚀剂存在的条件下,304不锈钢在3.5%(质量分数,后同)NaCl溶液中的点蚀电位。结果单组分的钼酸钠、葡萄糖酸钠对在3.5%NaCl介质中的304不锈钢点蚀有一定的抑制作用,且两种缓蚀剂有明显的协同缓蚀效应。结论当复配缓蚀剂配比为c(钼酸钠)∶c(葡萄糖酸钠)=2∶1时,其缓蚀效果达到最佳,点蚀电位为436 mV。     

焦磷酸钠在混凝土模拟孔溶液中的缓蚀性能

采用动电位极化曲线和电化学阻抗谱研究了焦磷酸钠在模拟混凝土孔溶液中对钢筋的保护作用。焦磷酸钠的加入导致混凝土中钢筋的腐蚀电位正移,主要通过抑制钢筋的阳极电化学过程起缓蚀作用。其缓蚀效果随焦磷酸钠浓度的增加而增大,在含0．04mol／L Cl-的混凝土模拟液中,当焦磷酸钠浓度为0．03mol／L时,其缓蚀效率可达到97．...     

熟料烧结过程中氧化铁反应行为的热力学分析

通过对Fe2O3与碳酸钠、氧化钙以及硅酸钙反应的热力学分析,明确Fe2O3在铝土矿炉料烧结过程中的热力学反应规律。热力学计算、分析结果表明:Fe2O3在正常烧结温度范围内能与Na2CO3或CaO发生反应,但更易与CaO反应形成2CaO.Fe2O3或CaO.Fe2O3,Fe2O3和Na2O.Fe2O3能使2CaO.SiO2和3CaO.2SiO2转变为CaO.SiO2,CaO.SiO2进一步与Na2O.Al2O3或Na2O.Fe2O3反应生成不溶的三元化合物而造成烧结法生产氧化铝过程中Na2O和Al2O3的损失。4CaO.Al2O3.Fe2O3不能由铁酸钙和铝酸钠相互反应产生,而可能是CaO、Al2O3和Fe2O3三者直接反应的产物,且在烧结条件下Na2O.Fe2O3可分解4CaO.Al2O3.Fe2O3。     

The high throughput assessment of aluminium alloy corrosion using fluorometric methods. Part I - Development of a fluorometric method to quantify aluminium ion concentration

This paper examines a new method developed for the rapid assessment of corrosion inhibitors and their combinations for aluminium alloy 2024-T3 (AA2024-T3). Two fluorometric probes, lumogallion and morin, were used to rapidly assess the concentration of aluminium ions in solution through the use of a spectrophotometric plate reader. Fourteen potential inhibitor compounds and other assay constituents were screened for fluoroprobe interference: sodium chromate, sodium metavanadate, cerium chloride, lanthanum chloride, europium chloride, gadolinium chloride, neodymium chloride, yttrium chloride, barium metaborate, sodium metatungstate, potassium phosphate, sodium metasilicate, sodium phosphate, and sodium molybdate. Calibration curves were established for the two probes.     

清洗剂对压缩机级间换热器超声清洗效果的影响

目的解决合成氨生产工艺中压缩工段的压缩机级间换热器结焦问题。方法采用超声清洗方法,选取OP-10、AEO、平平加和TX-10四种非离子表面活性剂和AES、十二烷基磺酸钠两种阴离子表面活性剂作为主剂,将各种主剂配制成浓度为10 g/L的溶液,在温度为30℃条件下对样管超声清洗,研究对比各试剂的清焦能力,并对其进行筛选与复配。同理,将氢氧化钠、碳酸氢钠、磷酸钠和碳酸钠四种碱性助剂配制成10 g/L的溶液,取同等质量的焦垢,通过对溶解后剩余焦垢量的称量计算其对焦垢的溶解率。结果非离子表面活性剂的清焦能力OP-10AEO平平加TX-10,阴离子表面活性剂的清焦能力AES十二烷基磺酸钠,且超声清洗最佳时间为10 h。碱性助剂的溶焦能力氢氧化钠(13.2%)碳酸氢钠(12.5%)磷酸钠(9.9%)碳酸钠(9.6%)。结论通过筛选和复配,OP-10和十二烷基磺酸钠作为清洗剂主剂、氢氧化钠为碱性助剂时进行超声清洗的效果较好。     

Effect of sodium silicate pretreatment on phosphate layer: Morphology and corrosion resistance behavior

Phosphating is a widely adopted treatment in industry for many purposes. In this paper, carbon steel was pretreated with sodium silicate before phosphating. X‐ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements were used to evaluate the pretreatment effect by sodium silicate on the phosphating layer. The results demonstrate that the phosphate layer pretreated by sodium silicate has a better corrosion resistance as compared with the un‐pretreated ones. More compact and uniform coatings composed of finer crystals were obtained with the pretreatment of sodium silicate.     

Titanium interaction with hydroxide-salt melts

The reaction of titanium with fused mixtures based on sodium hydroxide and various salts (sodium nitrate and nitrite, sodium and potassium chlorides, sodium orthophosphate, sodium meta-and orthotitanates, potassium oxyfluoride and hexafluorotitanate) is studied. The mechanism of inhibiting the corrosion of the studied metal in ionic melts that involve oxidants and titanium salts is discussed. Original Russian Text ? O.G. Zarubitskii, B.F. Dmitruk, N.F. Zakharchenko, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 5, pp. 529–533.     

Electrochemical behaviour of the tin anode in alkaline-stannate plating baths

In order to determine the conditions for tin plating, the anodic oxidation and passivation of tin have been investigated in sodium stannate solution in the absence and in the presence of sodium hydroxide. Both galvano-static and potentiostatic techniques were used. It was found that the passivation of this electrode is a complex process consisting of several steps. The passivation time increases with increasing stannate concentration and with decreasing current density. Addition of sodium hydroxide to the bath increases the passivation time. At low current densities and high alkali concentrations, passivation does not occur and the anode remains active and dissolves continuously as stannite.X-ray diffraction and electron spectroscopy for chemical analysis (X-ray photoelectron spectroscopy) examination confirmed the existence of tin(II) and tin(IV) oxides and hydroxides in the passive films formed potentiostatically in sodium stannate solutions in the absence and in the presence of sodium hydroxide.     

Behavior of calcium oxalate in sodium aluminate solutions

The stability of calcium oxalate is critical for the removal of sodium oxalate from sodium aluminate solutions. This study investigated the behavior of calcium oxalate in sodium aluminate solution containing sodium carbonate. Results show that calcium oxalate can be converted to tricalcium aluminate hydrate (TCA) and calcium carbonate in sodium aluminate solution and sodium carbonate solution, respectively. Elevating temperature, extending residence time, or increasing caustic soda concentration enhances the conversion ratio of calcium oxalate in sodium aluminate solution; as a consequence, anti-causticisation occurs. Stability of calcium-containing compounds in sodium aluminate solution containing sodium carbonate differs from that in sodium aluminate solution or sodium carbonate solution. Na₂CO₃ in aluminate solution accelerates the transformation of calcium oxalate; thus, alumina is lost because of 4CaO·Al₂O₃·CO₂·11H₂O and TCA formation. Calcium carbonate, 4CaO·Al₂O₃·CO₂·11H₂O and calcium oxalate can change into TCA in sodium aluminate solution at elevated temperature. Calcium oxalate remains relatively stable in dilute aluminate solution within a short residence time at low temperature. Thus, a novel process for removal of sodium oxalate by lime causticisation was presented and employed in an alumina refinery in China.     

调高水玻璃模数的研究

使用较高模数的水玻璃混制的型砂具有残留强度低、吹CO2时间短等优点，并有好的抗吸湿性和表面稳定性。一般低模数的水玻璃可以通过在其中加入一定量的无定形二氧化硅来提高模数，但研究表明，用这种方法调得的高模数水玻璃质量并不十分理想，在使用上存在很大问题。     

Flotation of Xinhua molybdenite using sodium sulfide as modifier

The feasibility of using sodium sulfide as the sole modifier for the flotation of Xinhua molybdenite ore was examined. The potential mechanisms involved in the different flotation systems were discussed. The comparative flotation results reveal that in the kerosene-sodium silicate flotation system, better recovery and grade of the molybdenum are obtained using sodium sulfide as the slurry pH adjustment agent than using CaO. Under the optimal conditions (64 g/t kerosene and 6 kg/t Na2S), satisfied recovery and grade of molybdenite concentrate can be achieved (84% and 8.2%, respectively), indicating that sodium sulfide is a potential substitute modifier of sodium silicate. The open-circuit flotation test results further confirm the effectiveness of sodium sulfide which may render recycling the tailing water possible and make the flotation process more environmental acceptable and more economical due to the less use of kerosene and scavengers.     

不锈钢在不同介质中的正负交变电脉冲处理及其对耐腐蚀性的影响

电化学诱导退火（EIA）是一种通过对不锈钢进行正负交变电脉冲处理提高不锈钢的耐蚀性的方法,但是其所用介质弧硝酸钠是一种强的致癌物质,且单一的处理介质限制了该方法的工业应用。本工作在不同介质中对不锈钢进行了正负交变电脉冲处理,通过XRD测试、金相观察、循环伏安测试、极化曲线测试等方法研究处理前后的组织变化、耐腐蚀性变化及...     

环保型无磷缓蚀阻垢剂的制备

以低分子量聚丙烯酸钠(PAAS)为基础,将聚丙烯酸钠、钼酸钠、D-葡萄糖酸钠、苯并三氮唑、六次甲基四胺等物质按一定比例复配成无磷缓蚀阻垢剂配方,采用碳酸钙沉积法评价其阻垢性能,用旋转挂片法和电化学法评价其缓蚀性能。优选出的最佳缓蚀剂配方为:聚丙烯酸钠15mg/L、D-葡萄糖酸钠14mg/L、苯并三氮唑13mg/L、钼酸钠18mg/L、六次甲基四胺14mg/L,其阻垢率为92.63%,缓蚀率为92.78%。该配方具有无磷、无毒、高效、环保等特点,具有重要的经济和利用价值。     

添加氧化铁高效热解脱除氰化钠

提出采用氧化铁催化热解高效除氰.采用XRD、DSC-TG、化学分析等手段对不同条件下添加和无添加氧化铁高效脱除氰化钠的机理进行研究.未添加氧化铁时,空气条件下,氰化钠在587.4℃开始发生分解;氩气条件下,氰化钠在879.2℃开始发生分解.添加氧化铁时,氩气条件下,大约60％的氰化钠在350℃热解30 min时发生分解...     

Carbon Transfer in Sodium System Under Thermal Cycling-Possibility of “Metal Dusting”

High temperature sodium systems encounter thermal cycling during operation. Under this condition, the behavior of carbon dissolved in sodium needs special attention. Carbon chemistry of sodium is very complex because of the existence of multiple carbon-bearing species. In addition, carbon exists both in the dissolved (“active”) and undissolved (“inactive”) forms. Under thermal cycling conditions, as the temperature is lowered, carbon may precipitate as sodium acetylide. The equilibrium carbon activity imparted by this species is high enough to cause the precipitation of iron carbide (Fe₃C) in ferrous alloys. The Fe₃C may be destabilized at lower activities of carbon in the environment (when the temperature is increased) and may decompose to a fine dispersion of metal and graphite. This phenomenon of “metal dusting” is extremely detrimental to the components of sodium systems. The article analyses the possibility of “metal dusting” in an operating sodium system.