电位滴定法测定苯甲酸钠含量

研究以pH玻璃电极为指示电极，甘汞电极为参比电极，电位滴定法测定苯甲酸钠含量，滴定终点由电位突跃来判断。此法简便、快速、准确，相对标准偏差为0．29％，相对误差为0．85％，测定结果与，药典法基本一致。     

自动电位滴定法测定铜产品中氯化物的含量

建立了自动电位滴定仪测定铜产品中氯化物的方法。以Ag Titrode电极作指示电极,选择DET模式确定等当点,用硝酸调节pH3,在乙醇—水溶液中滴定测得结果。该方法适用于硫酸铜、氧化铜、硫化铜和碱式氯化铜等铜产品中氯化物的测定,方法检出限为0.005 mg,加标回收率为98%~101%。     

电位滴定法分析水质中的氯离子

前言水质中氯离子的分析通常采用操作较繁的比色法及容量分析法。在电位法中,氯离子选择电极直接法测定氯离子,操作是简便快速的,测定灵敏度可达10~(-4)NCl~-,但准确度较差;采用准确度较高的电位滴定法,氯离子选择电极、Ag-AgCl丝电极、银电极、铂电极均可作为指示电极,但其滴定终点不突跃,通常需逐一记下滴定的毫升数及对应的毫伏数再作图后方能找出滴定终点。Prokopov采用丙酮非水介质进行电位滴定,以铂电极作指示电极,饱和甘汞电极(硝酸钾盐桥)作外参考电极,曾得到滴定的突跃终点。     

国内文摘(220—231)

<正> 摘220 TQ114.105.4 铅电极电位滴定联碱母液中的硫酸根——陈永德;《大化科技》1987,N3,18～22页以铅离子选择电极作指示电极,以饱和KCl—40%异丙醇、6%KNO_3双接界甘汞电极为参比电极,采用硝酸铅标准液作为滴定液,电位滴定联碱母液中SO_4~(2-)的方法。分     

电位滴定法测定电泳漆槽液中锌离子含量

取一定量的电泳漆槽液，用蒸馏水稀释后，加入醋酸铵缓冲溶液，使溶液ｐＨ＝６．５～６．８。以铜离子选择电极为指示电极，饱和甘汞电极为参比电极，用铜试剂标准溶液进行电位滴定。用二级微商法计算滴定终点，而间接求出电泳漆槽液中Ｚｎ＾２＋的含量。以铅离子选择电极为指示电极，用硝酸铅标准溶液进行电位滴定，用类似的方法即可测定电泳漆槽液中ＰＯ＾３－４的含量。     

三聚氰酸纯度化学分析方法

在水及非水介质中 ,用指示剂及电极电位判断终点 ,以酸碱滴定方法测定三聚氰酸纯度。结果表明 :用电位滴定和非水滴定较准确 ,相对误差分别为 0 .2 %和 0 .7%。     

电位滴定法连续测定双氰胺钠及杂质氯化钠含量

采用电位滴定法,以Ag NO3为滴定剂,银电极为指示电极,双盐桥饱和甘汞电极为参比电极,在低温酸性甲醛/异丙醇溶液中,连续滴定氯化钠和双氰胺钠溶液,以二阶微商法确定滴定终点,测定了双氰胺钠及其杂质氯化钠的含量。其原理是利用双氰胺银和氯化银溶度积的差异,在连续滴定过程中会出现两个电位突跃,从而实现分别滴定。实验优化了溶剂的配比及用量,在10 m L甲醛(Na OH中和)+80 m L异丙醇+1 m L硝酸介质中,冰浴条件下测定时,分析结果误差最小。用企业提供的标样验证了方法的准确性,对未知样中双氰胺钠及杂质氯化钠含量的测定结果满意。     

精密银量滴定终点的判别硫离子选择性电极法

在精密银量滴定中终点的判别是困难的。原因是滴定形成的卤化银既是沉淀,又会感光变暗,妨碍用指示剂观察终点。虽然电位滴定是有效的解决途径,但过去基于指示电极的重现性及灵敏度存在问题,并未广泛应用。近年来,离子选择性电极的发展,揭示了作为指示电极的可能性,据知一些单位也作了电位滴定试验。唯未作关于电位滴     

精密银量滴定终点的判别——硫离子选择性电极法

在精密银量滴定中终点的判别较难。原因是滴定形成的卤化银是沉淀且又会感光变暗,妨碍用指示剂观察终点。虽然电位滴定是有效的解决途径,但过去由于指示电极的重现性及灵敏度存在问题,故未广泛应用。近年来,离子选择性电极的发展,为选择指示电极提供了新的可能性。据了解一些单位也作了电位滴定试验,但未见有关电位滴定精密度实验的报导。本文介绍的用硫离子选择性电     

光亮镍镀液中硼酸含量的自动电位滴定

研究了光亮镍镀液中硼酸含量自动电位滴定的条件和方法。实验结果表明,用柠檬酸钾作掩蔽剂,防止Ni~(2+)的沉淀和其它重金属离子的干扰;加入丙三醇溶液,以pH复合电极为指示电极,进行自动电位滴定来测定硼酸,方法简便快捷,分析结果准确可靠。     

Récupération sélective du vanadium dans l'effluent d'un procédé de fabrication du blanc de titane

The selective recovery of vanadium from an effluent of a manufacturing process for titanium white (oxide) has been made. The process retained is based on the partial neutralization of the effluent by means of calcium carbonate and on the separation of metal hydroxides from calcium sulfate and the solution. The hydroxides are thereafter calcined in the presence of a sodium salt, so that sodium vanadate may then be extracted by washing with water. Vanadium is finally precipitated by the addition of ammonium chloride or pH adjustment. The experimental results obtained in the laboratory study of the effluent neutralization, the calcination and leaching of the hydroxides and the vanadium precipitation are presented and discussed. The yields obtained in the various stages and their interdependance are also discussed.     

NaBH4溶液催化制氢的阴离子效应研究

研究了Cl-和NO3-阴离子对NaBH4溶液现场制氢反应的影响,发现在制氢反应过程中存在着生成金属硼化物和生成金属氢氧化物的竞争反应.当溶液中阴离子为Cl-时,金属离子在催化NaBH4溶液制氢反应时将与硼结合,促使其活化为高活性金属硼化物,能有效促进制氢反应;当溶液中的阴离子为NO3-时,将诱导金属离子生成没有催化活性的金属氢氧化物,抑制制氢反应.     

Oxidation of ferrous hydroxide suspension. III

The rate equation developed in our earlier studies has been analysed and discussed. It has been found that the rate of oxidation of ferrous hydroxide suspensions obtained by the addition of calcium hydroxide, sodium and calcium carbonates, ammonium and sodium hydroxides follows zero order kinetics.     

Polyol-Derived Alkoxide/Hydroxide Base Catalysts I. Production

A metal methoxide is more expensive than a metal hydroxide and dissolves in methanol releasing a methoxide ion without producing water. The methoxide ion has a higher reaction rate making it more preferred for industrial biodiesel production. This study describes the preparation of alkoxide catalysts from metal hydroxides and non-volatile, non-toxic polyols. Heating aqueous solutions of metal hydroxides and different polyols (1,2-propanediol, 1,3-propanediol, glycerol, xylitol and sorbitol) under vacuum yielded polyol-derived alkoxide base catalysts (PDABC). Comparison of the drying process for respective sodium hydroxide-polyol combinations at two mole ratios of sodium hydroxide to polyol showed that drying at 2:1 mole ratio (metal hydroxide to polyol) was more efficient than that of 3:1. Dehydration of alkaline solutions containing three or more hydroxyl groups (glycerol, sorbitol and xylitol) was faster than drying similar solutions of diols. The empirical formula determined confirmed that the resulting powders contained mono-sodium substituted alkoxides at 1:1, 2:1 and 3:1 (sodium hydroxide: polyol) mole ratio. Fatty acid methyl esters were prepared from canola oil and methanol using glycerol sodium alkylate as a catalyst. The conversion yield of oil to methyl ester was greater than 99 %.     

RESISTANCE OF PLATE GLASS TO ALKALINE SOLUTIONS *

The resistance of polished plate glass to sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and sodium pyrophosphate was studied at various concentrations and temperatures. Test results showed (1) that the hydroxides are less corrosive than many alkaline salts; (2) that temperature has a marked effect on the rate of corrosion; (3) that increasing the solution above 10% does not alter the rate of attack appreciably; and (4) that the amount of stain on glass cannot be used as a measure of the amount of attack.     

插层改性水滑石及其对聚丙烯力学和阻燃性的影响

通过离子交换法制备了十二烷基磺酸钠、酒石酸氢钠、衣康酸改性的水滑石和十二烷基磺酸钠/衣康酸、十二烷基磺酸钠/酒石酸氢钠协同改性的水滑石（LDHs），通过熔融插层法制备得到了LDHs/PP复合材料。采用红外光谱（FTIR）、X射线衍射（XRD）、热重分析（TGA）对水滑石的结构和性能进行了分析表征，研究了LDHs/PP复合材料的力学性能和阻燃性。结果表明：上述几种单一和复合有机酸及盐改性剂都能不同程度地扩大水滑石的层间距；采用酸/盐协同改性的水滑石不仅有机基团含量较高，而且层间距大，显著提高PP的弯曲强度和阻燃性，表明酸和盐复合改性水滑石有显著协同作用及改性水滑石与PP基体相容性好。     

镁铝水滑石和镁铝铈水滑石的表面改性研究

将硬脂酸钠对LDHs表面进行湿法改性,探索了各改性条件对改性效果的影响。实验表明,当控制硬脂酸钠的改性时间为120rain,改性温度为80℃,改性剂的用量为水滑石质量的6％时,水滑石活化度最大,即改性效果最好。采用XRD、FT—IR等对改性前后的LDHs进行表征。结果表明,硬脂酸钠能与水滑石发生吸附作用,但水滑石的层状结构没有被破坏,层间距也不发生变化,证明硬脂酸钠仅改性水滑石表面,而没有插入到水滑石层间。     

Layered-Double-Hydroxide-Supported Pd(TPPTS)2Cl2: A New Heterogeneous Catalyst for Heck Arylation of Olefins

The Pd(TPPTS)₂Cl₂ (TPPTS: triphenylphosphine trisulfonate, sodium salt) complex is immobilized on layered double hydroxides by the ion-exchange method. This heterogeneous catalyst is successfully used in Heck arylation of olefins. The catalyst can be recycled several times with almost consistent activity.     

HEDP镀铜废水的组合处理方法

提出了一种HEDP镀铜废水的组合处理方法:用石灰乳液调节废水的pH至10~12后,加入氯化钙沉淀HEDP和酒石酸钾钠配位剂,从配合物中释放出的铜离子生成氢氧化铜沉淀;然后加入二甲基二硫代氨基甲酸钠沉淀残留的配合物中的铜离子,所释放出的HEDP及酒石酸根进一步与钙离子生成沉淀物。该方法简单、成本低,出水能满足排放要求。     

The Application of Alkali Dissolution Techniques in the Study of Aluminium Hydroxides and Oxyhydroxides

The effect of treatment with 5% sodium carbonate solution on aluminium hydroxides and oxyhydroxides likely to occur in soils has been investigated. Ultrasonic pretreatment, sample to solution ratio and temperature were factors studied. It is shown that particle size and degree of order of the sample influence the amount of alumina dissolved in 5% sodium carbonate solution in a fixed time; it is apparent, however, that both dissolution rate and solubility can be determining factors. Consequently, extraction with alkali at a low temperature and with a low solid: solution ratio is desirable for the preferential dissolution of poorly-ordered aluminous material from soil clays.