超声辅助提取-氢化物原子荧光光谱法测定香辛料中的铅

建立了一种操作简单、快速、高灵敏度、高提取效率的超声辅助提取-氢化物发生-原子荧光光谱法测定香辛料中铅的分析方法。考察了提取液的酸度、超声温度和时间对提取效率的影响,最终确定1.5%的硝酸为提取溶剂,超声时间和温度分别为60 min,40℃。考察了载流酸度、铁氰化钾浓度对铅测定时荧光值和线性系数的影响。实验表明铅含量在0~20μg/L范围内线性关系良好,线性相关系数大于0.999,检出限为2.6μg/kg,相对标准偏差为1.59%~3.52%,加标回收率为98.3%~108.3%,适用于香辛料中铅含量的检测。     

原子吸收法测定奶粉中的钙、铁、锌

用硝酸和高氯酸处理奶粉后，以质量分数为0.22％硝酸镧为释放剂，采用火焰原子吸收法测定同一样品中的钙、铁、锌元素的含量．结果表明．在选用浓度为0．15mol／L硝酸作介质条件下，共存离子不干扰．测定的RSD均小于1．59％(n=5)．回收率在98.6％-101．6％之间，与国家标准方法测定的结果基本相符。     

硝酸、硝盐生产技术新进展

总结近年来我国硝酸、硝盐工业生产的主要技术成果 ,如硝酸的尾气处理方法和规整填料的应用以及硝盐的直接法生产技术等。     

无机高分子混凝剂聚合氯化铁的合成方法

作者着重介绍了氮氧化物为催化剂,以填料塔为反应器,以钢铁酸洗废液或铁悄为含铁原料合成聚合氧化铁工艺。同时对于该气液反应的机理,影响因素,解决措施进行了讨论。     

NOX在氢氧化钠溶液中吸收速率的研究

通过实验对氮稀释气体中的NO_2/N_2O_4和NO/NO_2/N_2O_3在25℃时、在0.5M和1.0M氢氧化钠溶液中的吸收进行了动力学研究。当NO_2的浓度>2×10~(-7)mol/cm~8时,从排出的气流中观察到氧化氮的存在。故液体中的表面可能有酸膜存在。在此浓度下,NO_2的吸收速率与NO_2气体浓度的平方成正比。由此可以证实N_2O_4是主要的吸收和反应成份。生成的NO的三倍量与被吸收的NO_2的线性关系图表明,由N_2O_4水解生成的亚硝酸(HNO_2)实际上被分解成一氧化氮和硝酸。这是吸收器中存在酸性液膜表面层的有力证据。实验发现,N_2O_4一次不可逆水解的吸收速率常数H(KD)~(1/2)在25℃时为0.136m/s。这一数值远大于研究人员过去观察到的数值。在25℃的温度下,N_2O_3的一次不可逆溶解和水解的吸收速率常数H(KD)~(1/2)为2.71m/s,而Komiyama在1982年报告中给出的在15℃时的数值为2.55m/s。     

Ammonia volatilization from urea nitricphosphate and urea applied to the soil surface

Urea nitricphosphate (UNP) is an N-P fertilizer prepared by solubilizing phosphate ore with nitric acid and conditioning the product with urea. The product is acidic, and its nutrient analysis is 23-12-0. Urea makes up 74% of the N component of this material and the remainder comes from the nitrate added as nitric acid. In volatilization trials, UNP lost significantly less N than did urea in a noncalcareous soil (13 and 31% respectively). In calcareous soils the urea-N component of UNP exhibited loss patterns similar to those of urea. Soil pH remained stable at the center of the granule placement site during UNP hydrolysis, thereby reducing NH₃ loss, whereas the pH of the same soil treated with urea rose almost 1.9 units. The urea component of UNP appeared to diffuse from the center of the acidic microsite allowing hydrolysis to take place and permitting limited NH₃ volatilization to occur. UNP appears to be an attractive NP fertilizer in terms of nutrient analysis and resistance of the N component to volatile N losses as NH₃.     

法国GP公司硝酸、硝酸铵生产技术

主要介绍法国ＧＰ公司硝酸的生产工艺特点、尾气处理技术以及硝酸铵ＡＺＦ管式反应器生产工艺流程和工艺特点。     

Nitrogen dioxide effect in the reduction of nitric oxide by propane in oxidizing atmosphere

The role of nitrogen dioxide in the selective reduction of NO by propane over a Cu-MFI zeolite is investigated. NO₂ and NO reductions were carried out under similar conditions of reaction. In the presence of oxygen, the reduction of NO by C₃H₈ does not differ significantly from that of NO₂. In the absence of oxygen, the reduction of NO₂ by propane occurs with a partial decomposition of the nitric dioxide molecule. Such a decomposition leads to the formation of oxygen, which is responsible for the increase in catalytic activity by comparison with the same reaction performed with NO. NO₂ formed and released in the gas phase during the reduction of NO by propane in the presence of oxygen does not play a predominant role in the catalytic process.     

Evolution of the organic sulfur and other components during nitric acid leaching of Mequinenza coal

In this work, desulfurization by nitric acid leaching is studied in Mequinenza coal, whose characteristics are very low contents of sulfide and sulfate sulfurs in comparison with a very high content of organic sulfur that allows the selective attack on organic sulfur with regard to carbon to be clearly determined. Organic matter is made soluble at high temperatures and there is a threshold temperature for the same. The reaction involves an increase of nitrogen and oxygen, and a decrease of carbon contents. These variations reach a limit as the solubility of the organic matter progresses. The attack on inorganic sulfur is very fast, producing an initial leap as in the attack on organic sulfur, while the solubilization of organic matter is slower, because of which shorter times should be applied for the purpose of desulfurization.     

钯回收网在双加压硝酸装置上的应用

本文介绍了山西化肥厂双加压硝酸装置铂网及钯回收网的使用情况，并对钯回收网的应用进行了分析。