用DPD分光光度法检测饮用水中余氯

2001年9月1日起实施的《生活饮用水卫生规范》,对饮用水中余氯测定方法作了一些增删。考虑到原用显色剂邻联甲苯胺(OT)的致癌性,所以在标准方法中删除了OT比色法。增加了N．N-二乙基对苯二胺(DPD)分光光度法。我们通过反复试验比较,就我们所做实验的体会和一些易于混淆的问题进行讨论。     

对氨基二甲苯胺分光光度法测定水中余氯

建立了对氨基二甲苯胺分光光度法测定水中余氯的新方法。利用氯气在一定条件下能氧化对氨基二甲苯胺使其成为红色的氧化态形式 ,可以定量测定氯 ,实验条件如下 :最大吸收波长为5 2 0 nm ,p H控制在 2 .5～ 4.0之间 ,缓冲溶液用量为 2 ml,显色液体积为 3ml。氯浓度在 0 .1～2 .0 mg/L范围服从比尔定律。检测限 c L D为 0 .0 2 mg/L,水中常见的离子不干扰测定。该法用于自来水等样品中余氯含量的测定 ,加标回收率在 98%～ 1 0 4 %之间 ,结果准确可靠。     

双硫腙萃取光度法测定管网水中的余氯

建立了采用双硫腙萃取光度法间接测定管网水中余氯的新方法。其原理为：在中性条件下水中的余氯氧化锌粉，生成的锌离子与双硫腙生成1：2的红色配合物，用四氯化碳萃取该配合物．然后于535nm波长处测量吸光度，氯浓度在0．11～3．28mg／L范围内服从比尔定律。该方法的加标回收率为99．7％～100．7％。     

消除游离余氯对纳氏试剂分光光度法测定生活饮用水中氨氮影响的方法研究

纳氏试剂分光光度法是测定生活饮用水中氨氮的常用方法。水中存在游离余氯时,干扰氨氮测定。通过加入硫代硫酸钠脱氯进行实验研究,实验结果表明:投加硫代硫酸钠使其与游离余氯的质量比例在6:1～20:1时,氨氮的相对误差5.0%,加标回收率为85.0～97.8%,相对标准偏差RSD为2.08%,具有良好的准确度和精密度,为氨氮的准确测定提供了参考,具有实际应用价值。     

采用DPD分光光度法检测饮用水中氯消毒剂含量的研究

虽然DPD法在许多版本的《标准检验法》中被推荐为检测饮水中游离余氯或二氧化氯的首选方法,但在实际应用中,如果细节操作不当往往得不到满意的结果。对此笔者进行了一定的研究与总结,供同行参考。     

DPD分光光度法测定水中硫化物

DPD分光光度法是水中硫化物最常用的检测方法之一。针对实际操作中影响因素多、加标回收率低、较难掌握的问题,对该方法进行了改进。改进后的方法标准曲线线性良好,检出限低,加标回收率大大提高,标准偏差小,精密度好,准确度高,具有操作简单、投资少的优点,可应用于水中硫化物的检测。     

分光光度法测定OMC浓度的探讨

分光光度法测定ＯＭＣ浓度的探讨许小祥（常州煤气厂，常州２１３０１２）关键词煤气脱硫分光光度法ＯＭＣ浓度测定中图分类号ＴＵ９９６，Ｑ５４７．７目前，国内使用的脱硫液中ＯＭＣ浓度分析方法，大体有两种。一种是原子吸收光谱法，另一种是分光光度法。分光光度法...     

MD镇供水管网余氯衰减模拟

采用EPANET2建立了MD镇的管网水质模型,通过EPANET2的水质模拟分析与实际数据的对比,分析可能存在的问题。对可能存在的问题进行现场调查,进而对节点需水量和管壁衰减系数Kw进行调整,从而使模型中的模拟余氯与实测余氯相符。     

枯水期出厂水余氯突降原因与对策

针对江门市出厂水在枯水期出现余氯突降的现象,分析了出厂水余氯异常时出厂水及原水水质的变化情况、原水发生微污染时与河流潮汐的关系、原水氨氮和耗氧量的关系、原水氨氮和出厂水余氯的关系。结果表明,出厂水余氯出现突降是由于原水受到微污染造成的;氨氮、耗氧量以及河床水位可以作为原水微污染的预警指标,操作简单、有效;当预测到原水出现微污染时,采取加大和调整前后加氯量的方式,可解决由于原水微污染而引起的出厂水余氯突降的问题。     

多水源供水管网余氯优化控制研究及应用

为解决供水管网节点余氯浓度过高问题,建立了基于水力优化调度模型的余氯优化控制系统.将建立的余氯优化控制模型应用于SY市多水源供水系统,得到了各水厂不同时段的供水量、氯投加量及节点余氯浓度等信息.优化后的各水源供水量变化较大,平均氯投加量由2.226 mg/L降至2.191 mg/L,表明该模型在多水源供水管网余氯优化控...     

Comparison of three methods for measuring residual chlorine

Three EPA-approved residual chlorine detection methods were compared using standard solutions and water collected from the Savannah River which is used to cool reactors at the Savannah River Site (SRS) near Aiken, S.C. The testing was part of an experimental program to develop baseline data for the design of a proposed cooling tower for the K-reactor at the SRS. A series of total residual chlorine (TRC) measurements made simultaneously by three methods revealed that for the river water samples, the DPD method (Hach DR-100 kit) and the amperometric titration method produced statistically similar results while an ion-selective electrode method, standardized according to the manufacturer's instructions, provided significantly lower values. The DPD method (utilizing a Hach DR-100 kit) was the recommended method for future monitoring of the water evaluated because this method is simple, provides quick results, measures both total residual chlorine (TRC) and free residual chlorine (FRC) and is equally suitable for measurements in the field and laboratory.     

PSO-SVM与BP神经网络组合预测供水系统余氯的方法

针对余氯量在供水系统内非线性变化的特性,建立了PSO-SVM与BP神经网络组合模型对管网末端余氯进行预测分析。该模型通过粒子群优化算法(PSO),对SVM的特性参数进行优化;采用BP神经网络对模型进行残差修正。通过对单一的BP模型和SVM模型、组合模型的预测精度进行分析。结果表明:组合模型预测比BP和SVM单一预测均方误差分别降低了62.30%、75.29%,平均相对误差降低了55.03%、54.27%。综上所述,该模型具有强大的非线性拟合能力,预测精度高,运行稳定性强,对供水企业控制余氯的投加量和设置二次加氯点有一定的指导作用。     

Sampling design for water distribution network chlorine decay calibration

This paper provides a novel approach to determining optimal sampling locations for chlorine decay model calibration. Three questions are investigated: (1) What is the minimum number of chlorine sample locations needed? (2) How many combinations of sampling locations are available? (3) What is the optimal location combination? To answer the first two questions, the mathematical expressions of the chlorine concentrations between any two sampling locations are developed and sampling point relationship matrices are generated, then a mixed integer programming (MIP) algorithm is developed. Once obtained, the solutions to the first two questions are used to calculate the chlorine decay wall reaction coefficients and sensitivity matrix of chlorine concentration to wall reaction coefficients; then, sampling location combinations achieved in the second question are sorted using a D-optimality algorithm. The model frame is demonstrated in a case study.     

氨基磺酸盐减水剂在C50泵送混凝土中的应用

通过对几种外加剂的性能比较，阐述了混凝土早期强度、减水剂对水泥的适应性及其减水剂在实际施工中的验证，突出了氨基磺酸盐减水剂在高强混凝土中具有的多种优越性。     

Modelling chlorine residual decay as influenced by temperature

Temperature is one of the most important factors affecting chlorine decay rates in drinking water systems. In this article, temperature effect on chlorine decay rates in raw and treated waters was studied. Results show that temperature affects differently the fast and slow decay phases, the latter being more sensitive to temperature variations, as higher values of the activation energy parameter were obtained. Accordingly, an improvement to the temperature dependent two reactant model (a parallel second order model), in which the activation energies of each decay phase are distinct, is proposed and successfully used for chlorine decay modelling. In waters from transport and distribution systems, however, the fast decay phase is mostly negligible. In such cases, a single phase second‐order model in which the activation energy parameter is given by the slow phase reaction, is likely to describe temperature effect on chlorine decay accurately.