脱硫液中硫酸盐的测定方法比较

采用三种方法(重量法、EDTA滴定法、离子色谱法)测定脱硫液中硫酸盐的含量,并比较其测定结果。结果表明:三种测定方法各有优缺点,其中EDTA滴定法相对标准偏差小、费用低、操作简单、准确度高,是测定脱硫液中硫酸盐的最佳方法。     

离子色谱法测定煤灰中的三氧化硫含量

煤灰中三氧化硫含量的测定,主要有电位滴定法、库仑滴定法、重量法(艾士卡法)、硫酸钡质量法、高温燃烧中和法,但这些测定方法均存在一些问题,有必要找出一个更合适的测定方法.试验表明,先用1g碳酸钠在680℃烧结并洗出(提取)煤灰中的硫酸根,再用离子色谱法测定洗出液中的硫酸根含量,继而通过硫酸根含量与三氧化硫含量的定量关系可...     

分光光度法测定微量氯离子的研究与应用

1　前言含有有机物工艺水中氯离子的测定,是化工生产中常用的分析指标,其含量的高低,对生产的稳定性、生产过程参数的调节至关重要。目前,含有有机物工艺水中的氯离子的测定方法有硝酸银滴定法、汞量滴定法、比色法、离子选择电极法等。这些方法各有利弊,在生产中直接应用有一定的难度。分光光度法以其灵敏度高,选择性好,操作简单等优点广泛用于各种微量以及痕量组分的分析。由于氯化银沉淀不稳定,直接应用分光光度法测定结果不理想。笔者通过研究氯化银沉淀在明胶-乙醇水溶液中的稳定性。建立了一种新的测定微量氯离子的分光光度法,并应用…     

催化滴定法快速测定磷矿中的微量碘

目前,测定微量碘的主要方法有碘——淀粉比色法、碘——有机试剂比色法和催化法。其中催化法灵敏度最高,但催化法往往难于掌握,易受其他因素干扰,且需要繁琐的分离手续。本文拟定不需要分离的快速测定磷矿中微量碘的催化滴定法,并对矿样分解做了一些改进。碘的催化选用Ce~(4+)—As~(3+)系统,因为这个反应系统受其它离子干扰较少。1 关于共存离子的干扰问题     

两步滴定法测定阿司匹林肠溶片含量在教学中的应用研究

阿司匹林肠溶片含量测定方法较多,有高效液相色谱法、紫外分光光度法、同步扫描荧光光谱法、两步酸碱滴定法等,但在教学中最容易实现及大面积开展的是两步酸碱滴定法.通过对两步酸碱滴定法的样品处理及影响因素(浸取温度、颗粒直径、浸取时间)进行探究并优化,操作简单,结果准确可靠,重现性好,具有一定的教学实用意义.     

壳聚糖脱乙酰度测定方法的总结与比较

测定壳聚糖脱乙酰度(DD)的方法主要分为三类:①光谱法:紫外、红外光谱和核磁法;②破坏样品法:色谱法、差示扫描量热和元素分析法;③滴定法:酸碱、电位和胶体滴定等方法。对壳聚糖脱乙酰度测定方法进行总结与比较,为研究者选择最佳的壳聚糖脱乙酰度测定方法提供理论依据。     

导数离子色谱法在水质分析中的应用

建立了一种一阶导数离子色谱法测定水样中钙镁离子的方法,该方法在测定前无须对水样进行处理.考察了pH、温度、离子强度等对方法的影响,实验选择在pH为中性、室温下进行.由实验测定得到钙、镁离子的离子色谱图,并对谱图进行一阶求导,分别在钙离子和镁离子一阶离子色谱导数的零交点为6.5 min、7.5 min处读取另一离子的导数...     

水中硫酸根检测方法研究

水中硫酸根的测定方法主要有以下几种:重量法、比浊法、铬酸钡光度法、滴定法、离子色谱法、电感耦合等离子体发射光谱法、原子吸收分光光度法、极谱法、离子交换色谱等,也有少量关于紫外分光光度法测定水中硫酸根的报道。     

高锰酸钾滴定法测定钙片中钙的含量

为了准确测定钙片中钙的含量,建立了高锰酸钾容量滴定法测定钙片中钙含量的方法。实验样品经湿法消化后,在酸性溶液中,钙与草酸生成草酸钙沉淀。沉淀洗涤后,加入硫酸溶解,将草酸游离出来,在70—80℃条件下,用高锰酸钾标准溶液滴定与钙等当量结合的钙含量。测定结果的回收率（R）在98．40％-109．74％。用高锰酸钾滴定法测定钙片中的钙含量,简单、快捷、准确、干扰小。     

氧弹燃烧-离子色谱法测定氟树脂原料与涂料中氟含量的检测方法研究及不确定度评定

讨论了氟树脂原料及涂料样品中溶剂可溶性氟含量的测定方法.首先以氧弹燃烧分解氟树脂,把其中的氟转化为氟离子,然后用离子色谱法定量分析溶剂可溶性氟含量.在扩展不确定度取包含因子2,置信率为95％时,氧瓶燃烧-电位滴定法测定结果均处于氧弹燃烧-离子色谱法测定不确定度区间中,表明2种检测方法结果同样有效可信,且氧弹燃烧-离子色谱法操作简单、准确可靠.     

食品中草酸的测定

本文介绍用高效液相色谱法测定食品中草酸的含量,通过与经典滴定法测定草酸含量比较,实验结果表明:高效液相色谱法测定草酸含量结果准确,重现性好。说明本分析方法有关技术指标满足食品中草酸含量分析测试要求,具有操作简单、快速、易掌握、回收率高等特点,为食品中草酸含量测定提供简便快速的实用方法,并对其进行安全性评价,具有实践意义。     

硝酸氧化法制草酸过程中各组分的分析检测

研究了硝酸氧化淀粉水解液制备草酸反应液中各组分的检测方法。采用旋光光度计检测葡萄糖含量,结果表明,葡萄糖在溶液中的质量比与溶液的旋光值呈良好的线性关系;采用高效液相色谱分析母液中的草酸含量。其余酸性组分采用碱溶液滴定。     

乙醛酸和草酸的高效液相色谱分析

采用高效液相色谱法测定了草酸电合成乙醛酸中乙醛酸和草酸的含量,方法简便,成本低廉,效果良好。色谱柱为VP-ODS(150 mm×4.6 mm),流动相为稀磷酸水溶液(pH=2.7),流速为0.5 mL/min,柱温40℃,检测波长为212 nm。探讨了pH值及其它条件对色谱分离的影响。乙醛酸的线性方程为:Y=1.226×102X-7.053×102,线性相关系数R=0.999 6,相对标准偏差为1.5%,检出限为3.0×10-9g;草酸的线性方程为:Y=1.670×103X-5.563×104,线性相关系数R=0.999 9,相对标准偏差为0.8%,检出限为2.3×10-10g。     

Effect of pH, sulfate and sodium on the EDTA titration of calcium

The ethylenediaminetetraacetic acid (EDTA) titration method limits the measurement of calcium concentration to 50 mg/l in water. However, various acids and salt solutions are used in the investigation of the durability of concrete, and the adaptability of the EDTA titration method to determine the calcium in these solutions must be investigated. Hence, the purpose of this study was to investigate the interfering effects of hydrochloric acid, sulfuric acid, sodium chloride and sodium sulfate on measuring the calcium in the aqueous leaching solutions using the EDTA titration method. The calcium standard solutions were prepared using CaCl₂ with initial pH from −0.8 to 7 and calcium concentration up to 160 mg/l. Sulfuric acid and hydrochloric acid were used to prepare calcium solutions with lower pH. Salt solutions with 3% NaCl and 3% Na₂SO₄ were used to evaluate the interfering effects of salt elements such as sulfate and sodium on the EDTA titration. Results indicated that the EDTA titration method was reliable in measuring the calcium up to 160 mg/l, the maximum concentration investigated in this study, in hydrochloric acid with pH higher than zero and 3% sodium chloride solution. Sulfuric acid with pH higher than zero and 3% sodium sulfate solutions showed 3% to 4% less calcium in the solutions. Acid solutions with pH less than zero showed interference with calcium measurement.     

EDTA络合滴定钙、镁方法的改进

研究了用改进的ＥＤＴＡ络合滴定直接测定钙、镁的方法,即用乙酰丙酮掩蔽镁测定钙和用草酸钙沉淀除钙后直接测定镁的方法。结果表明,该新方法简单、快速、准确度和精密度高。     

Effect of ozonation pretreatment on the surface properties and catalytic activity of multi-walled carbon nanotube

Multi-walled carbon nanotube (MWCNT) has been used in the catalytic ozonation of oxalic acid in aqueous solution, which was pretreated using ozone and was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption and Boehm titration. The effect of ozonation pretreatment on the catalytic activity of MWCNT and the ozonation mechanism of oxalic acid in the presence of MWCNT were investigated. The results indicate that with the increasing pretreatment time, the atom ratio of oxygen to carbon and the number of surface acid groups on MWCNT increase, while the catalytic activity of MWCNT on ozonation of oxalic acid decreases, suggesting that the chemical characteristics of MWCNT mainly determine its catalytic activity on oxalic acid mineralization. The inhibition of tert-butyl alcohol on the degradation of oxalic acid is slight for pristine MWCNT catalytic ozonation and this inhibition trend becomes more obvious when MWCNT was pretreated by ozone. A free radical mechanism was proposed which involves both surface reactions and bulk reactions between the oxalic acid and active species.     

两性表面活性剂有效物含量的测定方法研究进展

对两性表面活性剂含量的测定方法以及其适用范围进行了综述,包括磷钨酸法、铁氰化钾法、高氯酸的电位差滴定法、酸性橙Ⅱ法、高效液相色谱法、紫外分光光度法等,为两性表面活性剂有效物含量的研究提供依据和帮助。     

Synthesis and characterization of PANI nanostructures for supercapacitors and photoluminescence

Polyaniline structures were synthesized through a chemical method using citric acid and oxalic acid as carriers and 5???m size ??-alumina particles as a template. The obtained nano-size pristine products were characterized using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, optical absorption spectroscopy, photoluminescence spectroscopy and cyclic voltammetry (CV). Nanofibrous PANI was obtained with oxalic acid, nanoparticles with oxalic acid and ??-alumina, net-like nanostructures with citric acid and spherical nanoparticles with citric acid and ??-alumina. The high intensity photoluminescence of PANI prepared with oxalic acid as a carrier is possibly due to greater chances of exciton formation resulting from increased ??-electron mobility. Electrochemical studies of PANI electrodes in 2.0?M H₂SO₄ were carried out at various scan rates. The CVs showed rectangular shape with added pronounced oxidation and reduction peaks.     

Electrochemically assisted photocatalytic degradation of oxalic acid on particulate TiO2 film in a batch mode plate photoreactor

Electrochemically assisted photocatalytic degradation of oxalic acid was studied in a batch mode plate photoreactor composed of particulate TiO₂ film immobilized on Ti metal plate (Ti/TiO₂ electrode) and Pt wires immersed in a flowing film of aqueous solution (Pt counter electrode). The degradation rate of oxalic acid was followed as a function of the potential of the Ti/TiO₂ electrode, the oxygen concentration and the light intensity. The presence of oxalic acid caused an increase in the measured photocurrent by one order of magnitude which is due to its reaction with photogenerated holes. The degradation rate increased with increasing potential up to 0.5 V vs SCE, then the increase was more gradual. Electrochemically assisted photocatalytic degradation of oxalic acid also proceeded in the absence of oxygen. The photogenerated electrons caused hydrogen evolution (low oxygen concentration) or predominantely oxygen reduction (high oxygen concentration) on the Pt counter electrode.