Iranian Journal of Chemistry and Chemical Engineering
Volume:11 Issue: 1, May-Jun 1992

In an attempt ot develop a one step process for the removal of H2S from sour gas, the engineering considerations were dealt with in two steps. In the first step it was attempted to derive the data required for establishing the design criteria for a pilot plant, by experimenting with a small bench scale. In this paper the results of the bench scale studies are summarized.

An enzyme electrode was developed using the enzyme sulfite oxidase (EC1.8.3.1) immobilized onto pig intestine. Hydrogen peroxide produced was monitored amperometrically. All experimental parameters such as pH, temperature, buffer consituent concentration, were thoroughly investigated and optimized when appropriate. The response to sulfite concentration was linear in the range 5.2×10-6 to 1.02×10-3 M. The proposed method was found to have a correlation coefficient of 0.952 when evaluated in compari-son with the standard titration method.

A sensitive and selective extraction – spectrophotometric method for the determination of trace amounts of palladium is reported. The method is based on quantitative extraction of brownish tetrabutylammonium tetraiodopalladium (II) ion pair into a small volume of chloroform at pH 1.3-12.0, followed by spectrophotometric measurements. The Beer’s law is obeyed over the range 0.02-1.09mgml-1 at 445 nm with the molar absorptivity of 5.3×103 lmol-1cm-1. The Sandell’s sensitivity is 0.80 mg cm-2 for 0.001 absorbance unit. The method has a wide range and is simple, rapid and free from interferences from many cations and anions. The procedure was applied to the determination of palladium in the activated carbon.

Two new prenylated flavonoids, named scariosin (1) and isorhynchospermin (2) were isolated from the leaves of Paracalyxscriosa together with kaempferol, quercetin, kaempferol 3-O-rutinoside and rutin. The structures of (1) and (2) were characterized as 8-C- prenyl – taxifolin 7, 3` – dimethylether and 6-C- prenylquenrcetin 7,4` – dimethylether by their chemical and spectral data, respectively.

Using the Lennard – Jones (12-6) potential, a new equation of state is obtained that can predict properties of both gases and liquids relatively well. This equation of state is given as (Z-a) V2=(A/V2) – B, where Z is the compressibility factor, A and B are constants, and a is an adjustable parameter that depends on the temperature, volume and the nature of the fluid, and its expression depends upon the fluid status. In this paper, appropriate expressions for argon are given for a, in the liquid region when 0.6

The condesation of glyoxal with benzylamine in the presence of formaldehyde leads to 2,4,6,8- Tetrabenzyl –2,4,6,8- Tetraazabicyclo [3.3.0] octane (6) in methanol. The scopes and limitations of the reaction have been determined. At low temperatures, a mixture of (6) and diol (7) is formed.

A physico – mathematical model has been developed that is suitable for biosensors incorporating membranes and bisubstrate enzymes. The set of equations regarding the transport of reactants across the memnrane, the bisubstrate enzymatic reaction, back diffusion of reactants and reaction products, are written down and simultaneously solved and transient response of the electrode is determined as a function of time. The model is assessed experimentally employing a simple glucose enzyme pH electrode. In the range practical for the enzyme pH electrode (0.01-0.1 M) there is satisfactory agreement between the theoretical predictions and experimental results. The model described is general and as well allows the determination of enzyme activity as a function of pH, thereby reflecting the range of substrate concentration that is measurable.

Two dimensional thin layer chromatography on polyamid sheets is a useful method for identification of PTH-amino acids which have very close Rf-values. The solvent systems described here are particularly effective and have an edge over other solvent systems used for the separation of PTH-amino acids. The solvent systems provide a clear separation of all PTH-amino acids except lle / Leu in a relatively short time.