A Raman spectroscopic study of lead and zinc acetate complexes in hydrothermal solutions

The aqueous reactions,
 
$$\begin{gathered} H^ + + SO_4^{2 - } = HSO_4^ - ,Na^ + + SO_4^{2 - } = NaSO_1^ - , \hfill \\ and H^ + + HSO_4^ - = H_2 SO_4 (aq) \hfill \\ \end{gathered} $$

 were studied as a function of ionic strength(I) at 150, 175, 200, 250, 300 and 320°C using a flow calorimetric procedure. Log K, ΔH, ΔS and ΔC
 p
 values at I=0 were derived from the data at each temperature. Using these experimental values, equations describing log K, ΔH, ΔS and ΔC
 p
 at I=0 and temperatures from 150 to 320°C were derived for each system. The use of equations containing identical numbers of positive and identical numbers of negative charges on both sides of the equal sign (isocoulombic reaction principle) was evaluated as a technique for the extrapolation of log K values valid below 100°C to temperatures above 150°C. This evaluation indicated that the principle gives good estimates up to 320°C.

Thermodynamic quantities for the interaction of SO 4 2− with H + and Na + in aqueous solution from 150 to 320°C

Gold-chloride complexes in very acidic aqueous solutions and at temperatures 25–300 °C: A laser Raman spectroscopic study

The hydrolysis of acetic anhydride to acetic acid in a hydrothermal/supercritical water reactor is monitored via in situ fiber-optic Raman spectroscopy to demonstrate the use of in situ spectroscop...

Monitoring Anhydride and Acid Conversion in Supercritical/Hydrothermal Water by in Situ Fiber-Optic Raman Spectroscopy

In situ measurements were made of several organic chemical reactions in supercritical water using fiber-optic probes, near-infrared excitation and CCD array detection. The reactions studied include the conversion of cyclohexene to cyclohexane and benzene in the presence of a platinum catalyst, conversion of cyclohexanol to cyclohexene in the presence of a cobalt catalyst and the homopolymerization of styrene. Transition to the supercritical state was marked by a sudden decrease in the background and the appearance of intense Raman bands for dissolved organic compounds. The results indicate that this method of study is both sensitive and rapid enough to permit kinetic measurements, even when reactions are completed in less than 2 min.

In situ fiber-optic Raman spectroscopy of organic chemistry in a supercritical water reactor

The design of a furnace assembly for maintaining aqueous solutions at temperatures up to 300°C and controlled pressures of up to 15 MPa is described. The apparatus is being used to monitor the chemical processes taking place in high-temperature aqueous solutions. Spectra of the Zn(NO3)2/H2O system and the HCl/H2O system are presented as examples.

Vibrational Spectral Studies of Solutions at Elevated Temperatures and Pressures. III. A Furnace Assembly for Raman Spectral Studies to 300°C and 15 MPa

C. I. Ratcliffe

Papers

Vibrational Spectral Studies of Solutions at Elevated Temperatures and Pressures. III. A Furnace Assembly for Raman Spectral Studies to 300°C and 15 MPa