Nashrieh Shimi va Mohandesi Shimi Iran
Year:2009 | Volume:28 | Issue:1|Papers Count:19

In the present study, the microbial production of hyaluronic acid by wild type Streptococcus zooepidemicus in semi defined medium in shake flask and 5 liters fermenter has studied. At first the culture condition and medium composition optimized. To experimental design, L-9 array of taguchi approach is used. The effects of glucose, yeast extract, sulphate and phosphate salts concentration and medium pH on hyaluronic acid production in batch culture in shakeflask was studied. Based on experimental data analysis, optimum condition for hyaluronic acid production was: 30 g/L glucose, 20 g/L yeast extract, 7.5 g/L sulphate and phosphate salts and medium pH 7. Of the culture condition examined, the yeast extract concentration had the most pronounced effect on the hyaluronic acid production. In optimum condition, hyaluronic acid production at 206 mg/L and 800 mg/L, in shake flask and 5 liters fermenter, in batch culture was obtained.

Utility system design greatly influences the total site design and operation. Therefore, several design approaches have so far been presented in open literature. However, no research has included the variation of physical and thermodynamic properties of steam due to pressure and temperature changes. This research, tries to present a mathematical model for determining optimum utility system considering variable physical and thermodynamic properties of steam. In this mathematical model the corresponding equations of physical and thermodynamic properties have been added into mass and energy balance equations. The complete model is then solved simultaneously in order to produce appropriate structure and optimum levels of steam as well as corresponding heat exchanger duties and turbines' loads. Two different case studies have been solved with this new model and results are compared with conventional method (considering constant physical and thermodynamic properties). The comparison shows that considering the variation of physical and thermodynamic properties of steam not only affects the details such as optimum distribution of exchangers' duties but it may also change the final structure. In one case study exchanger duty reduced by 15% and turbine load reduced by about 100%. This means that considering the variation of physical and thermodynamic properties of steam may change the structure of the final design.

In this research, experimental investigation of wastewater treatment ny MF-UF method is introduced. In the microfiltration section, heterogeneous ceramic element with a a-Al2O3 support and ZrO2/TiO2 coating with 0.1 mm pore size MF membrane has been used. In the Ultrafiltration section UFPHT20-6338 membrane was used. Effects of operating conditions such as pressure difference, flow velocity, shear stress, temperature, and concentration of organic components and pH on permeation flux, flux decline and fouling resistance have been studied. The results show that pressure difference more than 2 bar, flow velocity around 0.4 m/sec, temperature of 31°C and pH of 9 are the best operating conditions in MF section. In UF section, pressure difference more than 3 bar, flow velocity within 1-2 m/sec, temperature of 31°C and pH of 9 are the best operating conditions. Analysis of treated wastewater by MF-UF method shows 98.4%, 98.7%, 99.4% 99.75% and 3 points reduction in COD, BOD, TSS; Oil & Grease and pH respectively. This level of treatment satisfied the environmental standard. Results show that wastewater treatment by MF-UF membranes is possible and may compete and/or replace the prevailing conventional methods.

Because of its deep effect on the mass transfer parameters such as mass transfer coefficient, drop size must be investigated as an important factor in spray extraction column. In this work, at first, the variations of drop size versus the dispersed phase flow rate were studied and then, the effects of drop size on terminal and critical velocity were investigated. Two chemical systems were used for experiments. Spargers were set of nozzles in this experimental study. Results show that the maximum drop size increases up to a specific value with an increase in dispersed phase flow rate and then, it decreases with more increase in flow rate. Similar trend has been seen for variations of the terminal velocity against the drop size. Finally, a mathematical correlation is presented, based on dimensionless parameters, for predicting the maximum mean drop size. This correlation can predict the maximum mean drop size variations with an error about 9.41%.

Mathematical modeling and optimization of the steam reforming process of methane to syngas in a catalytic fixed bed reactor inside the furnace chamber is performed with axial dispersion and non-linear kinetic models. Validation of the model is carried out using the industrial scale experimental data and commercial software. Results showed a better agreement between this model and experiments than the commercial software. Optimization of the operational parameters was performed by Genetic algorithm considering two objective functions, minimizing methane consumption together with maximizing the carbon monoxide yield. In this study, the following cases were investigated; in the first case, optimization of the industrial scale operational conditions was performed, in the second one working at different outside tube wall temperatures and in the third case different porosities of the catalytic bed were considered The results of this work suggest higher quality of the syngas product with the lower feed consumption and improving the operational conditions after long time running the process.

In this research, SiO2 thin films were prepared using the sol gel dip-coating method on glass substrates to the study the effects of catalyst (HNO3 or NH3). Withdrawal speed and heat treatment temperature on the optical properties and morphology of the thin films. The study utilized the Ultraviolet-Visible (UV-Vis) spectrophotometer and Scanning Electron Microscopy (SEM). The catalyst type yielded a strong influence on morphology, and the resultant the optical properties of the thin films were noted. The acid catalyzed sol delivered a uniform and compact structure while the basic catalyzed sol had the ability to produce porous structures (with pore sizes of the order of 35-40 nm) in SiO2 thin films. Moreover, the basic catalyzed thin films exhibited better antireflection performance (or higher transmission) than the acid catalyzed ones.

In this paper, mass transfer coefficient in drop formation stage has been investigated in a counter-current spray extraction column and a mathematical correlation has been derived for exact predicting and evaluating this parameter by statistical analysis and applying the least square method. Spargers were perforated plates with the internal diameters of 0.8, 1 and 1.2 mm in this experimental study. The drop formation mass transfer coefficient was evaluated where the drops were separated from sparger and then, the drop was modeled based on its dependence on the existing parameters such as the drop's formation time, the mean drop diameter, the physical properties of the chemical system and some dimensionless numbers such as Reynolds and Eotvos. Consequently, it is demonstrated that the derived correlation can predict the drop formation mass transfer coefficient with an error about 1.12 % which shows that the empirical correlation and the experimental data are in a good agreement.

N-cyclohexylthiophthalimide (CTP), an affection chemical in rubber industry. is used in combination with sulfonamide accelerators as scorching time retarded. Due to its importance 'in rubber industry, providing a suitable method for CTP synthesis in accord with the local technology and available starting materials in Iran was the main goal of this project. Moreover, attempts have been made to provide a modified procedures plus an innovation in the method of the CTP synthesis. In our innovated method, the 2-[2-(4-nonylphenoxyethoxy] ethanol NP 10 has been used as an emulsifier in aqueous media in order to eliminate the organic solvent, reducing the reaction time, and modifying the product quality. This method is expected to have determining impact on industrial CTP production in accord with green sustainable chemistry.

In this research, the effects of industrial nitrogen sources including: soybean meal, corn steep liquor, (NH4)2SO4 and NH4NO3 on the growth of Saccharopolyspora erythraea and production of erythromycin were studied using basal seeding-media (1) and (2) and compared their results with that of control seeding-medium. The ingredients of the both of basal seeding media are same, with the exception, seeding medium (1) and seeding medium (2) have calcium carbonate and phosphate buffer, respectively. The concentration of erythromycin was measured by colorimetric and HPLC methods and the antibiotic potency was confirmed by microbiological assay. The results showed that corn steep liquor (20g/l) can be used as a sole nitrogen source instead of soybean meal, (NH4)2SO4 and (NH4)2HPO4 (that were used in the control seeding-medium). Soybean meal is not suitable as a sole nitrogen source in seeding-medium (1) and erythromycin production by this medium is 1.37 times less than that of seeding-medium (1) containing (NH4)2SO4 and (NH4)2HPO4 as complementary ingredients. Seeding-medium (2) containing corn steep liquor is not suitable for erythromycin production, because concentration of erythromycin by this medium is 1.1 times less than that of medium inoculated by seeding-medium (2) containing 40 g/l soybean meal. Various morphologies of hyphae were seen in the seeding-media containing different nitrogen sources. Maximum production of erythromycin was obtained by long-branched hyphae. Short hyphae are not suitable for erythromycin production. By consideration of erythromycin concentration and raw material prices, seeding-medium containing corn steep liquor, calcium carbonate, glucose and glycerol is proposed as optimum formulation for production of erythromycin.

Supercritical fluid extraction is one of the most useful methods for separation of lanthanides. In this study, the possibility of using Cyanex 302 and Tributyl Phosphate (TBP) as an extractor agent in supercritical condition for three cations namely Dyt+3, Nd3, La3 is examined In this study experiment design is used and the main effect of each factor (Pressure, Cyanex 302 and TBP) and the interaction between them are examined Maximum extraction has been observed, where all of three main factors were at their high level, and the extraction reported 23.4,42.49, and 58.4I%for La+3, Nd+3, Dy+3 respectively.

The main goal of this work is to study, the effect of dyeing and mordanting sequence on obtained color in single and combinatory dyeing of wool with pomegranate peel and cochineal. Woolen fabrics were dyed with cochineal, pomegranate peel and combination of these dyestuffs by using the potassiom aluminum sulfate (Potash-alom) as tanning agent. The mordanting procedure was carried out by pre-mordant, together- mordant and after mordant methods. Wide varieties of shades were produced by changing the sequence of operation in dyeing and mordanting procedures. The reflectance spectra of the dyed samples were prepared and subsequently the calorimetric evaluations were carried out. The fastness properties of the samples were also evaluated. It was observed that the sequence of operation in dyeing and mordanting procedures is effective on resulted shades and fastness properties.

The condensation product of beta-naphthalene sulfonic acid and formaldehyde as a dispersant and co-emulsifier was synthesized. Its molecular weight was determined by solution viscometry. Degree of polymerization and surface tension of the product were measured and its chemical structure was identified using FTIR and H-NMR.

The coal wastes of Zarand coal washing Plant are accumulated in near of this plant. The rate of extractable Alumina from the coal waste ash is about 27%. The amount of these wastes estimated about 107tons which about 1000 tons are added to them daily. In this study Alumina was extracted from wastes using: Lime-soda sintering, leaching of sinter, desilication of leaching solution, carbonation of desilicate solution with CO2 and precipitation of Al(OH)3 calcined Al(OH)2 processes respectively. The optimum condition achieved for each process as fallows: 1-Sinteringprocess; mol ratio of CaO/SiO2 =1.8. Na2O/Al2O3=1.3 in raw materials, particle size of raw materials: 12.5 % residual of 170 mesh sieve, time=35 minutes, temperature= 1275°C, sinter blain = 250 m2/kg. 2-Leaching process; solvent: NaOH 5.6 g/l solution, solid-liquid ratio =2, time=30 minutes and temperature=60°C 3-Desilication process; reagent: Ca(OH)2 10 g/l suspension, liquid - liquid ratio = 2, time=15 minutes, temperature: environmental temperature. 4-Carbonation process; amount of CO2 for Alumina precipitation in 250ml of 16.5 g/l Alumina solution: 1 liter/minutes for 20 minutes.5- Calcinations of AL(OH)3; temperature= 1250°C, time 30 minutes. The results showed that in optimum conditions about 74 % Alumina holding 99 % purification can be extracted from coal waste ash.

Transportation and distribution of natural gas are the most important subjects of gas industries in the country, because internal consumption or for exporting it. One of the problems that may be occurred in transportation lines is formation of gas hydrate crystals. Stability calculation must be done before the flash calculation to determine the number of phases that exist in equilibrium conditions. In this research stability analysis of systems that containing gas hydrate was done by minimization of distance of tangent plane of Gibbs free energy of system by genetic algorithm method. Because of non linear behavior of systems these multi component multi phase calculation were complex, thus the random optimization methods like (GA) was preferred. In this paper calculation of fugacity of components in vapor and liquid phase was done by using VPT equation of state and for solid phase VDW-P was used. In this work this calculation was performed for systems like methane-water (crystal I), methane-ethane-water (crystal I), methane-propane water (crystal II), methane-ethane-propane-water (crystal II), for 274 K and different pressures.