Iranian Journal of Chemistry and Chemical Engineering
Volume:25 Issue: 2, Mar-Apr 2006

An on-line UV-HPLC / APCI-MS (atmospheric pressure chemical ionization) tandem by a platinium C18 column with an isocratic solvent system after optimizing was applied to the separation and the identification of different carotenoids including astaxanthin, canthaxanthin, apocarotenoic ester, torularhodin and beta carotene. This method was used to identify particular carotenoids produced by newly isolated microorganism strain of Sporobolomyces ruberrimus H110 in our laboratory. The developed method allows to distinguish torularhodin and canthaxanthin, having the same molar mass but a different chemical structure. A detection limit of 9ng /ml for torularhodin observed. CV (%) for measurement of all carotenoid concentration was always below 3 %. Torularhodin and for a smaller part beta carotene were the two pigments identified in Sporobolmyces ruberrimus H110.

Ionomers are generally described by copolymers having either acrylic or methacylic acid as one component and the other component is mostly either ethylene or styrene. The objective of this research was to study the thermal behaviour and stability of ionomers of styrene with some alkali metal acrylates. These materials have been synthesized by neutralization of the respective copolymer containing 40 mole percent acrylic acid with sodium and potassium hydroxides in acetone medium. The copolymer of styrene–acrylic acid was made by solution polymerization in methanol using 2,2’-azobisbutyronitrile (AIBN) as initiator under nitrogen blanket at 60 oC. Copolymer composition was calculated from the monomer feed concentration. The ionomer samples were characterized using FTIR technique. Thermal behaviour of the ionomers has been studied under programmed heating in dynamic nitrogen atmosphere by using differential thermal analysis (DTA) and thermogravimetry (TG) and in vacuo using thermal volatilization analysis (TVA) techniques supported by product analysis. The thermal behaviour of the sodium and potassium salts of styrene-acrylic acid copolymer is found to be rather similar. Infrared spectroscopy, mass spectrometry and GC-MS techniques were used to examine the degradation products from TVA degradation. Quantitative measurements of the main product fractions under normal TVA conditions have been made. It is found that the main decomposition of the styrene-acrylic acid salts copolymers starts at about 350 oC and reaches maximum at 450 oC.

Tungsten trioxide (WO3) films have been coated on indium thin oxide (ITO) conductive glass substrate, using aqueous solution of peroxotungstic acid (PTA) by the sol-gel dip coating method. X-ray diffractometery (XRD) analysis confirmed monoclinic and triclinic structure for the film and powdered WO3 respectively. Fourier transforms infrared spectroscopy (FT-IR) exhibited the structure of peroxotungstic acid. The SEM micrograph of annealed species revealed micro cracks due to decrease of density and contraction of layers. Energy- dispersive X-ray (EDX) study determined 1:3 ratios of oxygen and tungsten atoms in the prepared films at heat treatment temperature higher than 200ºC. The electrochromical behavior was investigated in 1M HCL solution employing cyclic voltammetry. It was found that WO3 films demonstrated good reversibility at 200 ºC.

Pure and antimony doped SnO2 thin films have been prepared by the sol-gel dip coating technique on glass substrate using starting material SnCl2.2H2O as a host and SbCl3 as a dopant. Our experimental results revealed that, the quality of the coated films on the glass depends on process parameters. The effect of annealing temperature, dipping numbers and the dopant concentration on the structural and electrical properties were investigated. Duration of coating and dragging speed for each sample were 3 minutes and 90cm/min respectively. The films Characterization was carried out by X-ray diffraction pattern (XRD) and scanning electron microscopy (SEM). The XRD results showed the amorphous structure of deposited sample at 350C. Beyond this temperature (350C), the preferred plane with a random textured shifts to (101). By addition of 25g/lit antimony at 550C, the preferred plane shifts to (200). The electrical properties were determined by four point probes technique. Addition of 25g/lit antimony at 550C was reduced the resistivity of the SnO2 films to 0.9410-4 (cm).

A procedure for an efficient recovering of reflectance spectra of Acrylic paint samples from CIE tristimulus color values is described. By fixing a certain criteria based on color difference value, the proposed technique preliminarily selects a series of suitable samples from a main dataset containing the reflectance values of a series of different Acrylic paint samples, based on the color specifications of given samples. In this way, a series of different databases could be formed around a particular sample. The well-known principal-components linear model was used to recover the spectral data from their corresponding color coordinates by using only 3 basis functions. The surface spectra of a set of 2802 samples are collected for the recovery of the reflectance values of Acrylic paint samples whose tristimulus values were known. The role of the value of color difference for selecting suitable samples is discussed. The recovered spectra achieved by this method show considerable improvements in terms of root mean squarer (RMS) error and goodness-fitting coefficient as well as color difference values under different illuminants as compared to the recovery from the main database.

The bulk of the world’s phosphate reserves is located in sedimentary horizons that contain appreciable amounts of carbonate. During beneficiation of phosphate rocks, huge amounts of oversize phosphate rocks are rejected from crushers. This reject also mostly contains low tricalcium phosphate and high carbonate content. In this study, experiments have been carried out to reduce/eliminate carbonate content by leaching the ground phosphate rock with dilute hydrochloric acid solution. Effects of hydrochloric acid concentration, reaction time, temperature and liquid/solid ratio (vol./wt. basis) on the process have been studied. Under the reaction conditions, some of the apatite may be dissolved to form soluble monocalcium phosphate during the selective leaching. However, by specifying the pH of the process the lime milk can be used to recover the dissolved apatite. It has been observed that upon treatment of the ground rock with dilute hydrochloric acid, the P2O5 percent can be raised up to the industrially acceptable level due to the selective reduction/elimination of calcium carbonate content of the sample, depending on the reaction conditions as well as nature and size of the raw phosphate particles used for analysis.

Large reserves of coal in Tabas region of Iran are characterized by low ash and high caking index, suitable for use in metallurgy as coking coal. However, these coals cannot be gainfully utilized because of their high sulfur content. In this work, studies on desulfurization of Tabas coals were carried out in a batch reactor using various reagents. The most effective reagents, Fe2(SO4)3, FeCl3, NaOH, CH3OH, HNO3, and H2O2, were used to remove sulfur and ash from Tabas coals under reasonable pressure and temperature. Results obtained from coal desulfurization experiments using these reagents are presented in this paper. It was found that ferric sulphate is one of the suitable chemical reagent for desulfurization of Tabas coal which could be used to remove most of the fine distributed pyritic sulfur content.

Milk ultrafiltration is a membrane process, which is highly complex innature. The cost effectiveness of the process depends heavily on the flux permeate and the total hydraulic resistance of the membrane. In this work, a comparative study for the prediction of the performance of milk ultrafiltration with ANN and statistical method has been carried out. The result reveals that both methods carry out the prediction with a high degree of accuracy. However, the statistical method, contrary to neural nets, is both costly and time consuming and the accuracy of the data are also in doubt, as the operating conditions are not consistent throughout each of the test runs. The result also reveals that there is a good agreement between the predicted fluxes permeates and the total resistances of this work with the actual values. The findings of this study also shows that the artificial neural nets technique can be applied as a powerful tool and a cost and time effective way in predicting and assessing the performance of milk ultrafiltration process