Iranian Journal of Chemistry and Chemical Engineering
Volume:25 Issue: 1, Jan-Feb 2006

Graft polymerization of acrylic acid (AA) and ethyl methacrylate (EMA) onto starch (St) were carried out in aqueous solution using ceric ammonium nitrate (CAN) as redox system under N2 atmosphere. The effect of pH, reaction time, temperature, concentrations of CAN, St, and monomers on the graft yield was investigated. Monomer reactivity was in the following order: AA>EMA. The kinetics of the graft polymerization of AA and EMA onto starch in same system with CAN was studied by acid-base and boromometric titration, respectively. The rate expressions for graft polymerization are Rg=k[AA]0.92[CAN]0.56[St]0.46 and R/g=k/[EMA]0.92[CAN]0.53[St]0.48 and a suitable mechanism is suggested. The graft copolymers were investigated by FT-IR spectroscopy. The overall activation energy of graft polymerization of AA onto starch was found to be 36.25 kJ.mol-1 within the temperature range 20-40°C, and for graft polymerization of EMA onto starch is found to be 11.88 kJmol-1 within the temperature range 25-45°C.

The effect of SDS (0.03-0.07 M) and Brij-35(0-0.003 M) concentrations and temperature on retention parameters of 30 solutes in micellar reversed- phase liquid chromatography systems were studied using solvation parameter model. The system constants were determined by multiple linear regression analysis from experimental values of the retention factors with known descriptors by computer using the program SPSS/PC. The experimental results showed that the variation in concentration of surfactants (SDS, Brij-35) changes the cavity formation (m) and hydrogen-bond acidity (b). The value of m decreases while the value of b increases as the SDS concentration increases. The value of m and b slightly decrease as the Brij-35 concentration increases. Variation of temperature (25-38˚C) showed changes in cavity formation (m) and hydrogen-bond acidity (b). A comparison of the predicted and experimental retention factors indicated a satisfactory agreement between the two. Normalized residual plot showed that the contribution of the systematic modeling errors is approximately minor using the linear solvation energy relationship (LSER) equation. The value of cross-validated r2 was 0.973.

Separation of some biogenic amines via RP-HPLC using mixed micellar mobile phase was investigated. The compounds were derivatized before hand by dansyl chloride as a chromophoric reagent. Appropriate conditions for separation, were determined by studying factors such as temperature, type and percentage of organic modifier, concentration of surfactants (SDS and Brij-35) and the pH of the mobile phase. The number of theoretical plates (N), asymmetry factor (B/A) and selectivity factor (α) considered as criteria for finding the appropriate conditions for separation. Appropriate condition, were: 40˚C, 40 mM SDS, 0.5 mM Brij-35 and 10% 1-propanol at pH=5.

In this study 152 bacterial strains were isolated from the contaminated oils in the southwest of Iran. Hemolysis was used as a criterion for the primary isolation of biosurfactant producing-bacteria. Fifty five strains had haemolytic activity, among them tweleve strains were good biosurfactant producers by measuring surface tension and emulsification activity.Two microorganism showed the highest biosurfactant production when grown on paraffin and glycerol as the sole carbon source. Glycolipid production by the isolated bacterium using different carbon (n-hexadecane, paraffin oil, glycerol, molasses) and nitrogen sources (NaNO3, (NH4)2SO4 and CH4N2O) was studied. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), emulsification capacity (EC), and thin layer chromatogeraphy. Best result were obtained when using glycerol at a C/N ratio of 55/1 and sodium nitrate as nitrogen source. Production of the rhamnolipid, expressed by rhamnose was 4.2 g/L and the yield in relation to biomass, was Yp/x = 0.65 g/g. Additionally, physical-chemical characteristics of the spent broth with and without cells showed a low critical micelle concentration of 19 mg/L and a decrease in surface tension to 20 mN/m (%).

Gephyrotoxin-223 was formally synthesized from chiral synthon 1 which has been chemoenzymatically synthesized in the presence of Candida Antartica lipase.

The optimum fermentation times of black tea manufactured by two systems of Orthodox and CTC (cut, tear & curl) were investigated by measuring the quality parameters of black tea, like: theaflavin, thearubigin, highly polymerized substances and total liquid colour during the fermentation stage. Optimum fermentation times from the beginning of fermentation were determined to be 60 min and 150 min for the fine and coarse tea of orthodox manufacturing, respectively. The optimum fermentation time of CTC tea process was 30 min. Most theaflavin content of Orthodox and CTC processes were 0.63 and 0.82 percent of the total dried solids of infusions, respectively. Total color of CTC manufacturing was 16% higher than Orthodox process.

Apotransferrin (apo Tf) in 0.1 M N-(2hydroxyethyl)piperazine-N2-ethanesulfanic acid at 25 ˚C and pH 7.4 has been titrated with acidic solution of Tb3+. The binding of Tb3+ at the two specific metal-binding sites of transferrin was followed from the changes in the difference UV spectra at 245 nm. The molar absorptivity per binding site for Tb3+-Tf is 22,500 ± 1000 M-1cm-1. To determine the Tb-Tf binding constants, apo Tf was titrated with Tb3+ solutions which also contained nitrilotriacetic acid as a competitive chelating agent. The sequential macroscopic equilibrium constants for the binding of two metal ions are log K1 = 9.96 ± 0.38 and log K2 = 6.37± 0.38. Titrations of both C-terminal and N-terminal monoferric transferrin with Tb3+ indicate that terbium binding is stronger at the C-terminal binding site. The value of K1 for Tb3+ is substantially higher than the teransferrin binding constants reported for larger lanthanides. It is possible that there are steric interferences to the binding of larger lanthanides. However, an analysis of the transferrin binding constants using linear free energy relationships for metal complexation suggests that the metal ionic radius alone is not the major determining factor. A change in the number of coordinated water molecules in the aqueous ions for Tb3+ compared to the larger lanthanides may be a more important factor.

Density (/g cm-3) and viscosity (/10-2gcm-1s-1=1centipoise,CP) of guanosine monophosphate (GMP) and adenosine triphosphate (ATP) referred to as nucleotide, and 2-deoxy adenosine (DOA) and thymidine (TMD) as nucleoside along with their integral furanose sugar, 2-deoxy ribose (DOR) from 0.0004 to 0.0014mol kg-1 solution have been measured at 288.15, 293.15 and 298.15K at atmospheric pressure. The  was fitted into the Masson and  in Jones-Dole equations for apparent molal volume (V /cm3mol -1) and viscosity coefficient ((r-1)/m=B/kg mol -1=10 3gmol -1) data. The V and  were also regressed for V 0 and 0 values known as the limiting constants and illustrate solute-solvent and solute-solute interactions of systems. The apparent molal volume of their various integral units like adenine, guanine and thymine of nucleotides and nucleosides are estimated by V 0 The V 0 0 and B values have been used to elucidate the hydrophilic and hydrophobic interactions. The V 0 values are negative over the whole range of the compositions which infer greater intermolecular forces and the biomolecules as water structure breakers

In the temperature range of 10 to 80 ºC and in a batch digester, a typical activated sludge was digested aerobically. Reaction rate constants were determined by measuring the amounts of volatiles removed from the suspended solids at different time intervals during the process. The maximum value of the reaction rate constant (0.45 d -1) occurred in the temperature range of 55-60˚C. Removal of indicator organisms (pathogens) in the sludge, during the batch digestion, was also studied. Sludge digestion at 60 ºC provided a noticeable difference in reduction of the indicator organisms as compared to digestion carried out at 55 ºC. Optimum thermophilic aerobic digestion for high rate removal of volatile suspended solids and effective inactivation of pathogens happened in temperature range of 60-65 ºC.