茜素用作络合滴定氧化钙衬色指示剂的试验

络合滴定氧化钙的指示剂中,以钙黄绿素灵敏度较高,但此指示剂色变欠佳。为了增加终点变色对比度,文献[1]提出加入百里酚酞为衬色指示剂。百里酚酞在强碱性溶液中为纯蓝色,使络合滴定氧化钙终点呈现红紫色,终点指示不太理想。另外,百里酚酞加入量对终点变化影响很大,量少,钙黄绿素荧光不易消失;量大,又使终点蓝色太深,变化不明显。为此寻找一种理想的衬色指示剂,就是本试验的目的。     

配位滴定氧化钙指示剂的选择

配位滴定钙的指示剂中,以钙黄绿素灵敏度为最高,但色变欠佳。为了增加终点变色对比度,加入百里酚酞为衬色指示剂。百里酚酞在强碱溶液中为纯蓝色,使配位滴定钙终点呈现红紫色,终点指示不太理想。我们为此进行了试验。 1 指示剂终点对比 用EDTA在强碱溶液中络合滴定钙,对比了几种与钙黄绿素混合的双色或三色指示剂,见表1。     

CMP混合指示剂的变相应用

ＣＭＰ混合指示剂的变相应用徐淑荣辽宁省铧子监狱（１１１３１２）目前，水泥化学分析中测定氧化钙用的钙黄绿素—甲基百里酚兰—酚酞混合指示剂（简称ＣＭＰ）是三者以１：１：０．２的重量比、再加一定量在１０５℃下烘干的硝酸钾共同研细而成的粉末状固体指示剂。过去...     

CMP三混指示剂的选择及使用

ＣＭＰ三混指示剂的选择及使用王晓宁陕西耀县水泥厂（７２７１００）在水泥工业分析中，ＣＭＰ三混指示剂广泛应用于ＣａＯ的ＥＤＴＡ络合滴定中，该指示剂不象ＭＴＢ指示剂要求的ｐＨ范围那样严格，且终点返色轻，结果稳定。滴定终点的颜色由绿色荧光消失并转变为红色，...     

浅析水泥氧化镁、氧化钙含量检测过程中的“返色”现象

在GB/T176-2008水泥氧化镁、氧化钙的实验中,测定氧化钙时,常会出现滴定"返色"的现象,控制好三乙醇胺标准溶液加入前后试液的pH值范围,能避免因为Al3+干扰而引起的"返色",有利于提高检测结果的准确性,使检测偏差降到最低。     

石膏中氧化钙含量的测定研究

结合生产实际,为了更准确地测定石膏中氧化钙的含量,检验其纯度,首先利用国标法测定石膏粉末中氧化钙的含量。在相同条件下,分别讨论不同钙指示剂对实验效果的影响,实验结果表明:钙紫红指示剂具有更好的灵敏性和可靠性。     

离子交换法测定水泥中SO3时滴定终点指示剂的选择

测定水泥中SO3的方法有碘量法、硫酸钡重量法、库仑滴定法和离子交换法等,由于离子交换法具有经济、简便、快速的特点,所以在测定中多采用该法。我公司近期在用离子交换法测定水泥中的SO3含量的过程中,发现用酚酞作指示剂,滴定终点明显延长,颜色变化缓慢,终点不易判断,操作员因对终点颜色的色差判断不同,非常容易出现偏差,     

浅谈酸碱滴定中指示剂的选择

文章简述了酸碱滴定指示剂的选择.     

混合碱溶液滴定实验中指示剂的改进

大一无机及分析化学实验中的混合碱溶液滴定实验常采用双指示剂法,由于终点变化不敏锐,导致有较大的误差。采用混合指示剂来指示滴定终点,测定结果与标准溶液真值进行比较,判断测定方法准确度高低。实验证明,多组混合指示剂颜色变化明显,滴定终点容易判断,滴定结果准确,优于常规的双指示剂法。     

EDTA滴定法测定石灰石中氧化钙含量不确定度的评定

对EDTA滴定法测定石灰石中氧化钙含量进行了不确定度评价。分析了整个测试过程中不确定度的来源,并对各个不确定度分量进行了计算。结果表明,EDTA滴定法测定石灰石中氧化钙实际标准含量的差异,主要存在于标定溶液测定的数据值与样品测定值的偏差。当测定石灰石样品中氧化钙质量分数为51.73%时,其扩展不确定度为0.20%(k=2)。     

A study of nitrous oxide decomposition over calcium oxide

A study of N₂O decomposition reaction in a fixed bed a reactor over bed of CaO particles has been conducted. Effects of parameters such as concentration of inlet N₂O gas, reacting temperature and content of CO₂/ CO gas present in the reacting materials on the decomposition reaction have been investigated. The results showed that the conversion of N₂O decomposition was accelerated by the increase of reaction temperature, and the existence of CO, while the rate was hindered by the existence of CO₂. Heterogeneous gas solid reaction kinetics was proposed for N₂O decomposition and compared with homogeneous reaction kinetics. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University.     

水泥厂窑尾袋除尘器酸结露现象的分析和研究

分析了水泥厂窑尾袋式除尘器酸结露、酸腐蚀的原因,估算了水泥窑尾烟气在不同SO2浓度下的烟气酸露点;并结合水泥行业实际情况,针对避免和减少袋除尘器酸结露和腐蚀问题,提出保证窑尾烟气温度高于酸露点减少冷凝现象、降低漏风率、采用耐腐蚀材料(推荐考登钢)和采用防腐涂层等一系列相关措施。     

磷酸氢钙吸附去除铀试验研究

采用磷酸氢钙吸附去除铀,考察了反应时间、温度、pH值、铀初始质量浓度、磷酸氢钙投加量等因素对铀去除效果的影响,并从热力学和动力学原理进行了分析。结合扫描电镜、X衍射等分析结果探讨了磷酸氢钙去除铀的机理。结果表明,一定量的磷酸氢钙对铀的吸附容量随着铀初始浓度的增大而增大,随着温度的升高而升高。当pH值为4,磷酸氢钙投加量为200 mg/L时去除效果最好,铀的吸附率高达99%,吸附容量最高可达341.157 2 mg/L,吸附反应在120 min时基本达到平衡;吸附反应在动力学上符合准二级动力学方程,在热力学上符合Langmuir方程。X衍射分析表明磷酸氢钙在吸附铀后晶体结构发生了改变;扫描电镜分析表明,磷酸氢钙在吸附铀后由分散而规则的晶体外观转变为粘结且附有无定型絮状物的外观。     

Experimental study of the inverse fluidized bed biofilm reactor

A new apparatus, the inverse fluidized bed biofilm reactor, is described. Introduction of the so called inverse fluidized bed, in which low density particles covered by a biofilm are fluidized by downflow of the liquid, allows control of the biofilm thickness and provides a high oxygen concentration in the reacting liquid. Characteristics of the reactor were studied by carrying out two important biotechnological processes: aerobic wastewater treatment by a mixed bacterial culture, and ferrous iron oxidation by the bacteria Thiobacillus ferrooxidans. The bioreaction rates per unit volume of the reactor were up to 14 times higher than those in the equivalent airlift bioreactor. The structure of the liquid flow was determined by a tracer method.     

A study of nitrous oxide decomposition over calcium oxide in combustion condition

A study of N₂O decomposition reaction over a bed of CaO particles in a fixed bed reactor has been conducted. Effects of parameters such as concentration of inlet N₂O, reaction temperature and effects of CO, CO₂, O₂, and NO gas presented in the combustion gas environment have been investigated. The experiment showed that the N₂O decomposition reaction was accelerated by the increase of reaction temperature, and the existence of CO, while the reaction was hindered by the existence of CO₂, NO. O₂ also affected the N₂O decomposition. Heterogeneous gas-solid reaction kinetics were proposed for the reaction conditions and compared with homogeneous reaction kinetics.     

SBR中皂含量测定电位滴定终点的研究

试验研究了用盐酸标准溶液滴定SBR中皂含量时电位滴定终点pH值对测定结果的影响,结果表明,按现行方法中规定的滴定终点进行试验,皂含量测定结果包括了胶料中防老剂及填充油中的其它碱性物质,试验确定了pH值4.8为新的滴定终点,使测定值与真实值更为接近。平行测定相对标准偏差为1.54%（n=8）。     

纯碱副产物氯化钙的提纯实验研究

以提高纯碱副产物氯化钙的纯度为目的,采用过滤、重结晶、加氧化钙、斜发沸石吸附等除杂方法,进行了氯化钙提纯的实验研究。结果表明：在工业级氯化钙的基础上,通过提纯使氯化钙的含量提高7.3%（质量分数,下同）,氯化钠的含量降低52%,氯化镁的含量降低84%,铁含量降低98%,并去除了铅和铜,最终产品中氯化钙、氯化钠、氯化镁、水不溶物、铅、铁、铜的含量均达到了食品级氯化钙的指标。     

A mechanistic study on the simultaneous elimination of soot and nitric oxide from engine exhaust

The non-catalytic interaction between soot and nitric oxide (NO) resulting in their simultaneous elimination was studied on different types of reactive site present on soot. The reaction mechanism proposed previously was extended by including seven new reaction pathways for which the reaction energetics and kinetics were studied using density functional theory and transition state theory. This has led to the calculation of a new rate for the removal of carbon monoxide (CO) from soot. The new pathways have been added to our polycyclic aromatic hydrocarbon (PAH) growth model and used to simulate the NO–soot interaction to form CO, N₂ and N₂O. The simulation results show satisfactory agreement with experiment for the new CO removal rate. The NO–soot reaction was found to depend strongly on the soot site type and temperature. For a set of temperatures, computed PAH structures were analysed to determine the functional groups responsible for the decrease in the reactivity of soot with NO with increasing reaction time. In isothermal conditions, it was found that as temperature is increased, the number of oxygen atoms remaining on the soot surface decreases, while the number of nitrogen atoms increases for a given reaction time.     

黄磷炉渣制取硫酸钙的实验研究

以黄磷炉渣为原料,经HNO<,3>溶液浸出,SiO<,2>以无定形水合二氧化硅的形式分离,钙元素以Ca(NO<,3>)<,2>的形式进入到浸出液,浸出液经H<,2>SO<,4>沉淀,然后经洗涤、干燥可得到优质的CaSO<,4>产品.讨论了H<,2>SO<,4>质量分数、H<,2>SO<,4>与Ca(NO<,3>)<,2...