硝酸银试纸法检测乙炔气中硫磷含量的可靠性探究

建立了乙炔气中硫、磷含量的硝酸银试纸显色定性检测实验装置,并与化学法的定量检测结果进行对比,研究了试纸变色的硫、磷含量边界,并考察硫化氢用量对硝酸银试纸显色情况的影响。研究表明:硝酸银试纸即使30 s不显色,硫化氢含量仍在25×10~(-6)左右,磷化氢含量仍在60×10~(-6)左右。同时,硫化氢含量和用量对硝酸银试纸的显色有交互影响,浓度越低,显色时所需的气体用量越多,反之亦然。     

试纸法测定土壤中有效磷

试纸法测定微量磷,是将钼蓝法所用部分试剂分别浸在纸上。试剂与待测磷素在纸条上反应显色,根据以深浅与磷含量成线性的关系直接比色本法对实验条件做了最佳选择,并应用了一定浓度的活性剂高分子材料浸纸,使显色均匀、集中,有助于灵敏度的提高。     

化学分析法精确测定羟基磷灰石中的Ca和P含量

分别采用改进的EDTA络合滴定法和高锰酸钾氧化返滴法精确测定了羟基磷灰石(HA)等物质中的钙含量,通过对比实验、精密度实验和加标回收实验对基准碳酸钙、分析纯磷酸三钙、分析纯磷酸氢钙及合成的羟基磷灰石中的钙含量进行了测定,对结果的标准偏差、相对标准偏差及回收率做了比较分析和讨论.结果表明,两种方法测定结果相当吻合,改进的EDTA法比高锰酸钾法更快速、简便,能够满足钙磷酸盐中钙含量的准确测定.钙含量测定的最大标准偏差和相对标准偏差分别为0.057和0.15 %.同时,采用磷钼酸喹啉容量法测定了样品中的磷含量.     

浅析铋磷钼蓝光度法测定钢铁及合金中磷含量操作条件控制

铋磷钼蓝光度法测定磷含量此方法显色体系简单,操作快速,稳定性好,相对偏差较小,精密度和准确度令人满意.但是此方法影响因素较多,在学生实验和比赛过程中,会出现测定结果不准确,甚至偶尔还会出现不显色的现象.本文结合显色条件,就显色温度、时间、酸度的影响和操作要点进行分析.     

六偏磷酸钠中正磷酸盐的测定方法研究

针对有关于六偏磷酸钠性能的测定，特别是六偏磷酸钠含量的测定通用方法局限于磷钼酸喹啉重量法测定五氧化二磷含量，在这些测量方法中，只讨论了总磷含量和非活性磷含量的测定，并没有涉及正磷酸盐含量的测定等的问题，提出一种六偏磷酸钠中正磷酸盐的测定方法，可解决现有六偏磷酸钠性能测定中的不足，通过测定出六偏磷酸钠中正磷酸盐含量，可以对各种不同品牌的六偏磷酸钠进行评价，或者对生产条件影响六偏磷酸钠进行研究及调控。     

测定循环冷却水中聚磷酸盐含量的新方法——差示分光光度法直接测定聚磷酸盐

本文在考察了正磷酸盐和聚磷酸盐在铝兰测定法中显色特性差异的基础上,建立了不同还原剂用量的差示分光光度法。该方法可直接测定循环冷却水中的六偏磷酸盐、三聚磷酸盐或者六偏与三聚的含量,省去了测定正磷的步骤。方法简便快速,准确度高,回收率为98～102%,工作曲线线性范围为0.04～50ppm。可能共存的正磷酸根及硅酸根等离子对本方法不产生干扰。     

钼酸铵分光光度法测定总磷影响因素探讨

通过实验对本公司循环冷却水中总磷酸盐测定的各个因素进行研究,从中选择适宜的分解剂用量,显色条件和消解时间,以验证本公司现用磷酸盐测定方法的准确性。     

尿素中缩二脲含量快速测定方法的建立

通过对尿素产品中缩二脲含量测定方法进行研究和系列实验,改进了试剂配制方法、称样方法、显色温度、显色时间等操作条件,并可使用便携式分光光度计到取样现场直接测定,优化了现有尿素中缩二脲含量测定方法.缩二脲含量测定通过精密度实验、回收率实验和对比实验,验证了新建立的测定方法快速准确可靠.     

磷钒钼黄比色法测定循环水中磷酸盐的探讨

对磷钒钼黄比色法测定磷酸盐显色条件进行选择,找出最佳显色条件并改进。改进后方法的测定范围在0～0.014mg/mL,相关系数为1.0000,并对循环冷却水中磷酸盐作准确实验,得回收率为90%～100%,与原钼蓝法作对比实验,说明循环冷却水磷酸盐的测定选择磷钒钼黄比色法较理想,具有良好的选择性和重现性。     

循环冷却水中磷含量的测定

提出用钼酸铵分光光度法测定循环冷却水中的磷酸盐含量,严格控制好硫酸,各试剂的加入量,以及显色时间.相对于用钼酸铵目视比色法,更省时间,且测定范围更宽.     

OVERVIEW OF THE RESULTS OF THE INTERNATIONAL WORKSHOPS ON KINETIC MODEL DEVELOPMENT AT THE 1983 DENVER AND 1985 CHICAGO AIChE MEETINGS

An approximate analytical solution presented by Cooper for predicting the radius of the frozen phase, S, of human tissue during cryosurgical operations has been widely used. Based on consideration of the Stefan number, Ste, another approximate analytical solution for S has been developed in this paper. The new technique has the advantages of simple form, reasonable structure, good accuracy, and quantitative agreement with experimental data.     

新型(多喷嘴对置)水煤浆气化炉的开发

通过大型冷模和小型热模试验开发新型（多喷嘴对置）水煤浆气化炉,介绍了中试结果及其与德士古水煤浆气化技术的比较,并阐述了新型水煤浆气化炉的技术优势,结果表明,多喷嘴对置气化技术优于引进的德士古技术。     

Gelcasting of alumina based ceramic cores containing yttria for single crystal and directional solidification blades

Abstract

Ceramic cores play an essential role in investment casting. In this paper, gelcasting process has been successfully employed to fabricate alumina based ceramic cores containing yttria for single crystal and directional solidification blades. Based on an investigation of the formability of different ceramic slurries, material compositions of ceramic cores are determined by experiments. A proper sintering process is developed to get low sintered shrinkage, high apparent porosity and high room temperature flexural strength. The high temperature properties of ceramic cores are improved by dipping in water based yttria sol and resintering. The test results show that comprehensive properties of alumina based ceramic cores containing yttria fabricated by gelcasting are better than those of AC-1 ceramic cores made by the Beijing Institute of Aeronautical Materials, China, and that the ceramic cores can be applied to single crystal and directional solidification blade casting.     

基于锁相环的电磁感应水处理器研究

通过分析电磁感应水处理器的工作原理和影响水处理效果的关键因素,建立了决定除垢效率的溶液感生电流和磁感应强度的解析模型。针对感生电流对溶液做功的平均功率与激磁信号的函数关系,提出了一种将双极性脉冲馈入LC电路产生谐振的优化方法,采用自动频率跟踪技术对其脉冲的输出频率进行实时调整,从而保证谐振电路输出最优频率的激磁信号,以提高电磁感应水处理器的处理效果。实验结果表明:该水处理器可以更有效地提高除垢效率,且对环境的适应能力更强。     

串联式压电传感器测定水中阴离子表面活性剂

基于阴离子表面活性剂与季铵盐反应前后电导的改变和压电传感器能响应溶液电导率的性质,建立了串联式压电传感器测定水中阴离子表面活性剂的新方法。在５００μｇ氯化十六烷基吡啶存在下,十二烷基磺酸钠的浓度在３．６×１０－７～５．７×１０－５ｍｏｌ·Ｌ－１范围内与压电传感器的频移值呈线性关系,相关系数为０．９９８９,检测下限为１．７×１０－７ｍｏｌ·Ｌ－１。用此法测定了环境水样中的阴离子表面活性剂,其加标回收率为９４．４％～１００．２％,相对标准偏差小于４．９％     

催化动力学分光光度法测定微量的汞

在pH=4.0的乙酸-乙酸钠缓冲溶液中,微量的Hg(Ⅱ)对亚铁氰化钾与1,10邻-菲啰啉(1,10-0-phen)显色反应有催化作用,加入硫脲能提高其灵敏度,显色程度与Hg(Ⅱ)量在一定范围内呈线性相关,借此建立测定微量Hg(Ⅱ)的分光光度法。实验表明,有色溶液最大吸收波长为515 nm,摩尔吸光系数ε=3.72×106L/(mo.lcm),相关系数为r=0.999 1,催化程度与Hg(Ⅱ)浓度在(0.0~1.2)μg/25 mL范围内符合比耳定律,选择性好,利用该方法直接测定人工合成水样中汞的含量,以及河水、池塘水中微量汞的含量分析,结果满意。     

Characteristics and potential applications of a novel forward osmosis hollow fiber membrane

There has been a resurgence of interest in forward osmosis (FO) as a potential means of desalination, dewatering and in pressure retarded osmosis, which Sidney Loeb was advocating over 3 decades ago. This paper describes the characteristics and potential applications of a newly developed FO hollow fiber membrane, which was fabricated by interfacial polymerization on the inner surface of a polyethersulfone (PES) hollow fiber. This FO membrane presents excellent intrinsic separation properties, with a water flux of 42.6 L/m² h using 0.5 M NaCl as the draw solution and DI water as the feed with the active layer facing the draw solution orientation at 23 °C. The corresponding ratio of salt flux to water flux was only 0.094 g/L, which is superior to all other FO membranes reported in the open literature. To evaluate different application scenarios, various NaCl solutions (500 ppm (8.6 mM), 1 wt.% (0.17 M) and 3.5 wt.% (0.59 M)) were used as the feed water to test the performance of the FO membrane. The membrane can achieve a water flux of 12.4 L/m² h with 3.5 wt.% NaCl solution as the feed and 2 M NaCl as the draw solution, suggesting it has good potential for seawater desalination.     

PGSS-drying: Mechanisms and modeling

Micronization of polyethylene glycol from aqueous solutions has been successfully performed with particles from gas-saturated solutions (PGSS)-drying process, producing spherical PEG particles with average particle size of 10 μm and residual water content below 1 wt%. Based on experimental results, an analysis of the fundamentals of the process has been developed, discussing mass and energy balances, phase equilibrium conditions, mass transfer rates and atomization mechanisms. Some discrepancies between experimentally observed moisture concentration in powder and calculations based on the mass balance and the phase equilibrium have been observed, which have been attributed to the kinetic evolution of pressure and temperature along the expansion path. The static mixer used to saturate the solution with CO₂ has been analyzed with phase equilibrium and mass transfer calculations, concluding that a significant fraction of water is extracted to the gas phase already in the static mixer, and high CO₂ concentrations are achieved in the liquid due to the high solubility of CO₂ in PEG. All experimental trends of variation of particle size with process parameters can be explained considering a flash-boiling atomization mechanism dependant on the concentration of CO₂ in the solution after the static mixer.     

Self-Catalyzed Synthesis of Organo-Silica Nanoparticles

A procedure has been developed which utilizes aminopropyltriethoxysilane (APS) as the catalyst and a comonomer in the production of hybrid organo-silica nanoparticles. Particles ranging from ca. 100 to 500 nm can be prepared using organo-silanes of the type R'Si(OR)₃, where R'= Me, vinyl, allyl, or other hydrophobic groups and R = Me or Et, in a water/surfactant solution. Based on elemental analysis, up to 10 mol% of APS was incorporated into the siloxane particle network. It is thought that the amino groups are located mainly on the surface due to their hydrophilicity and APS' relatively slow rate of hydrolysis and condensation.     

气固非催化反应移动边界问题的拟稳态正交配置解法

本文以拟稳态条件下颗粒内部各点转化率的直接计算为基础，通过对边界移动问题的理论分析，用正交配置法求解移动边界问题。计算结果表明，该法准确、快速，适合于体积反应模型及粒子模型等气固非催化反应模型的求解。