甲酸-乙酸-水-氯化钙体系汽液平衡盐效应的研究

本文采用Otsuki-Williams式汽液平衡釜测定了甲酸-乙酸-水体系及甲酸-乙酸-水-氯化钙体系在98658.28Pa下汽液平衡数据。氯化钙的加入量为0.5mol/(kg溶剂)。结合盐效应的作用情况,对相图进行了分析。研究结果表明:氯化钙的加入对体系起了物理化学作用,它与盐溶、盐析现象有关。     

甲酸-乙酸-水-醋酸钠体系汽液平衡的盐效应

采用Otsuki-Williams式汽液平衡釜测定了甲酸-乙酸-水-醋酸钠体系在9.866×10⁴Pa下汽液平衡数据。醋酸钠的加入量为2mol/(kg溶剂)。结果表明:醋酸钠对体系起物理化学作用,也起化学作用。它涉及到了两种盐对各组分的盐溶、盐析和盐效应的不规则现象。根据实验数据,绘制了汽液平衡相图、各组分挥发度等于1的曲线和甲酸-乙酸在体系中相对挥发度等于1的曲线,用以判别、分析盐效应的作用。     

火焰原子吸收光谱法测定钙盐试剂中的痕量镉

采用巯基棉分离富集钙盐试剂中的前量镉,用火焰原子吸收光谱法进行测定。方法简便、快速,结果满意。样品测定的相对标准偏差均小于４．８１％。     

新银盐光度法测定磷酸氢钙中的微量砷

以硝酸银－乙酸－聚忆烯醇－乙醇作为砷化氢吸收液,Ｚｎ－ＫＩ－ＳｎＣｌ２为还原体系的新银盐光度法测定了磷酸氢钼中的微量砷。Ａｓ＾２－含量在０－７．５μｇ／５ｍＬ范围内服从比耳定律。应用于磷酸氢钙样品中Ａｓ呈测定,回收率９６－１０３％,方法检出限为２．８８×１０＾－６ｇ／Ｌ,ＲＳＤ为０．９４－５．５０％,测定结果与标准方法基本一致。     

Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins

通过观测红外光谱的强度变化研究了在不同温度下盐离子对谷氨酸和三种水溶性蛋白质(细胞色素C、DsbC和DsbC-G49R)的影响. 证实了Onsager反应场理论. 区分并且定义了随温度变化的蛋白质盐效应盐溶过程和解离过程. 同时利用Van't Hoff关系式对实验结果进行线性拟合,获得了蛋白质及其二级结构在上述两个过程中的热力学常数.     

酸性品红褪色光度法直接测定食盐中的碘

在HCl-KBr的介质中,碘酸钾氧化酸性品红褪色的程度与碘酸根含量在一定范围内呈线性关系,从而建立了褪色光度法测定碘的新方法。试验结果表明,酸性品红的最大吸收波长为545nm,碘的含量在0.4—2μg·mL-1范围内时,符合比耳定律,表观摩尔吸光系数为3.7×104L·mol-1·cm-1。用于测定食盐中的碘,结果满意。     

XRF法测定工业循环水中硫和氯

以光谱纯试剂做标准系列 ,氦气光路 ,XRF法测定工业循环水中硫和氯。方法简便、快速 ,可满足生产要求。     

Anti-Hofmeister series properties found for a polymer having a π electron system and acidic protons

Anti-Hofmeister series properties have been found for a polymer (PVA-T) having a π electron system and acidic protons, which were prepared by introducing trimellitic anhydride to poly(vinyl alcohol) (PVA). Aqueous dispersion of PVA-T became clear in the presence of 1 M Na₂SO₄, a typical kosmotrope, due to dissolution of the solid polymer sample, while the turbidity in the presence of 1 M KSCN, a typical chaotrope, hardly changed. Being consistent to the salt effects, PVA-T hydrogel, which was prepared by chemical cross-linking, showed marked swelling in sulfate solutions, whereas the swelling degree was only marginal in thiocyanates.     

Prediction of solubilities of salts,osmotic coefficients and vapor–liquid equilibria for single and mixed solvent electrolyte systems using the LIQUAC model

The electrolyte model LIQUAC has been used up till now to predict osmotic coefficients, mean ion activity coefficients, the vapor–liquid equilibrium (VLE) behavior, the solubility of gases in single and mixed solvent electrolyte systems, and solubilities of salts in aqueous solutions. In this paper, the required expressions for the calculation of salt solubilities not only in aqueous systems, but also in organic solvents and water–solvent electrolyte systems were deduced in detail based on the LIQUAC model with a fixed reference state and thermodynamic relations. Four salts (NaCl, KCl, NH₄Cl and NaF) and two solvent (water and methanol) were selected to test the derived expressions. The results show that the LIQUAC model with a fixed reference state can be used to predict osmotic coefficients, solubilities of salts in aqueous solutions, vapor–liquid equilibria, and the solubilities of salts in water–organic solvent systems with strong electrolytes.     

基于EEMs及PARAFAC的洪湖、东湖与梁子湖CDOM组成特征分析

国内外关于长江中下游地区如洪湖、东湖及梁子湖等大中型浅水湖泊DOM组成特征的分析较少,本文基于2007年9月—10月洪湖、东湖与梁子湖34个站点野外实地采样数据,运用三维荧光图谱(EEMs)与平行因子分析(PARAFAC)模型,着重分析了三个湖泊CDOM吸收荧光特性及组成特征。结果表明,CDOM在350 nm处吸收系数a(350)在三个湖泊表现为洪湖极显著高于东湖与梁子湖(p<0.001);三个湖泊CDOM光谱斜率S_280～500与a(350)呈极显著负相关(R2=0.781, p<0.001)且洪湖S_280～500值极显著低于东湖与梁子湖(p<0.01);光谱斜率比值S_R值也表现为洪湖显著低于东湖与梁子湖(p<0.05)。PARAFAC模型解析得到两个类腐殖质组分(C1, C2),两个类蛋白质组分(C3,C4),其中组分C1与C2呈极显著正相关(R2=0.884,p<0.001),组分C3与C4亦为极显著正相关(R2=0.677,p<0.001),这表明三个湖泊CDOM组分C1与C2,C3与C4来源相似,然而统计结果并未发现四个荧光组分与DOC及Chl-a浓度之间存在任何显著性相关关系。三个湖泊荧光指数FI₂₅₅(HIX),FI₂₆₅,FI₃₁₀(BIX)与FI₃₇₀值均表现为东湖显著高于梁子湖(p<0.05),极显著高于洪湖(p<0.01),这意味着东湖富营养化程度高于洪湖与梁子湖。