文献类型：期刊文献

英文题名：Calorimetric investigation of reaction Ca(NO3)2 + Na3PO4 in water and microemulsions saturated with CO 2

作者：Du, Zhongyu[1]; An, Xueqin[2]; Fan, Dashuang[1]; Shen, Weiguo[1,2]

机构：[1] Department of Chemistry, Lanzhou University, Lanzhou 730000, China; [2] School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China

年份：2011

卷号：43

期号：6

起止页码：322

外文期刊名：International Journal of Chemical Kinetics

收录：EI(收录号：20111813956359)

语种：英文

外文关键词：Calorimetry - Fourier transform infrared spectroscopy - Ionic strength - Rate constants - Enthalpy - Kinetics - Microemulsions - Sodium Carbonate - Activation energy - Carbon dioxide - Hydroxyapatite - Surface active agents

摘要：The reactions of Ca(NO3)2 + Na3PO 4 in water and water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/hydrocarbon microemulsions saturated CO2 with various molar ratios of water to surfactant R, oil phases, and surfactant concentrations were investigated by isothermal titration calorimetry. The product of the reaction was confirmed to be sodium-and-carbonate-substituted hydroxyapatite (NaCO 3HAP) by Fourier transform infrared spectra (FTIR), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). From calorimetric measurements, the molar enthalpies of solution of water in the AOT/n-dodecane system, and the molar enthalpies, the rate constants, and the activation energies of the reactions were determined. It was found that the enthalpy of solution of water in AOT/n-dodecane micells and the molar enthalpy of the reaction in the microemulsions increased with the decreases of R until R = 7; below that they kept almost constant. It may be attributed to the increase of the ratio of the bound water to the free water with the decrease of R until there was no free water when R 1 was affected by the ionic strength of the medium and log k 1 showed a linear dependence on 1/R in the whole range of R we investigated. It was also observed that the rate constant and the enthalpy of the reaction remained almost unchanged when the surfactant concentration and the nature of oil phase varied. ? 2011 Wiley Periodicals, Inc.