Scientia Iranica
Volume:17 Issue: 1, 2010

TiO2 was doped with various types of rst row transition metals towards the degradation of dichloromethane, chloroform, carbon tetrachloride and a mixture of carbon tetrachloride and chloroform. Zn2+/Fe3+/TiO2 photocatalyst with the ratio of 0.0005: 0.0005: 1 was revealed as the best catalyst in this study. 41.05% of dichloromethane, 49.45% of chloroform and 37.84% of carbon tetrachloride were degraded by this catalyst in the presence of UV light 6 W, 354 nm, irradiated for 90 minutes, and oxidized VOCs gases were analyzed using GC-FID. In this study, the new species of CHCl+2, CH2Cl+, CCl+2 and OCl+. CHCl+2 was detected to form from the photocatalytic degradation of chloroform while some new fragments, such as OCl+, CHCl+2 and CH2Cl+, are observed during the photocatalytic degradation of carbon tetrachloride.

In the current work, synthesis of an environmental-sensitive superabsorbent hydrogel using -rays is described. Grafted polyacrylonitrile onto a homogeneous solution of starch and kappa- Carrageenan hybrid backbones created a smart material with reversible behavior. The reaction parameters i.e. acrylonitrile, starch and kappa-Carrageenan concentration, as well as -irradiation time a ecting the water absorbency of the hydrogel were optimized using the Taguchi method, in order to achieve a hydrogel with high swelling capacity. FTIR spectroscopy was used for con rming the structure of the nal product and the morphology of the synthesized hydrogel was examined by a scanning electron microscope. The swelling behavior of the optimized hydrogel sample in various NaCl concentrations and swelling kinetics in distilled water were investigated. The pH-reversibility and on-o switching behaviors of entitled smart hydrogel make it a good candidate for consideration as a potential carrier for bioactive agents like drugs.

A highly e cient, simple and rapid method for the chemoselective preparation of acylals from aldehydes and acetic anhydride in the presence of a catalytic amount of polyethylene glycol-bound sulfonic acid PEG-SO3H 1.67 mol% at room temperature is described. Ketones do not react under these reaction conditions.

Nitrophenols can be obtained in high yields via nitrosation-oxidation of phenols by 3- methyl-1-sulfonic acid imidazolium chloride f[Msim]Clg as a new Br nsted acidic ionic liquid and NaNO2 at room temperature. In situ generation of HNO2 and a radical-cation mechanism via the nitrous acid catalyzed pathway appear to be applicable to phenol nitration using this reagent system.

Beside their worldwide abundance, oil recovery from fractured carbonate reservoirs is commonly low. Such reservoirs are usually oil-wet, thus, water ooding leads into early breakthrough and low recovery due to the high conductivity of the fracture network, negative capillary pressure of the matrix and, consequently, the poor spontaneous imbibitions of water from fractures into the matrix during the course of water ooding. In such problematic reservoirs, changing the wettability of the matrix toward water-wetness can improve spontaneous imbibition by changing the sign and, thus, the direction of capillary forces, resulting in an improvement of water ood eciency and, consequently, oil recovery. A study of this technique on the most signi cant Iranian oil-producing reservoir, Asmari, seems necessary. Some surfactants of di erent ionic charges have been examined in this study. Asmari reservoir rock samples were used and the petrophysical and mineralogical properties of the rock samples were determined by both thin section analysis and core ooding techniques. Interfacial tension measurements have been done to decide surfactant solution concentrations. Capillary pressure measurements were conducted both before and after wettability alteration. Amott-Harvey and USBM wettability indices were determined. Among the surfactants, a cationic one could best raise the level of spontaneous imbibition. Favourable changes in the wettability indices were observed.

The e ect of an e cient biosurfactant produced from Pseudomonas aeroginosa MR01, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks, was investigated. In a core holder set-up, bearing a number of limestone- and dolomite-containing core samples, biosurfactant ooding resulted in oil recoveries as large as 20% to 28% Residual Oil RO. Biosurfactant injection in less permeable rocks in a range of 0.5 to 32 md was more successful, in terms of oil production. In the case of the least oil recovery via biosurfactant ooding, incubation of the core with a biosurfactant solution at reservoir conditions, increased the recovery from 13% residual oil at zero resting time to 15% after a resting time of one week and to about 30% after a resting time of about two weeks. Based on interfacial tension measurements, salinity and, to a larger extent, biosurfactant reduced interfacial tension. When salinity increased from 170000 to 200000 ppm, the fraction of residual oil production increased to about 20%.

Considering the non-ideal behavior of uids and their e ects on hydrodynamic and mass transfer in multiphase ow is very essential. Simulations were performed that take into account the e ects of mass transfer and mixture non-ideality on the hydrodynamics reported by Bozorgmehry et al. In this paper, by assuming the density of phases to be constant and using Raoult''s law instead of EOS and the fugacity coe cient de nition, respectively, for both liquid and gas phases, the importance of nonideality e ects on mass transfer and hydrodynamic behavior was studied. The results for a system of octane/propane T = 323 K and P = 445 kPa also indicated that the assumption of constant density in simulation had a major role to diverse from experimental data. Furthermore, comparison between obtained results and previous reports indicated signi cant di erences between experimental data and simulation results with more ideal assumptions.

This paper presents the utilization of a newly developed technique for development of a proxy model in reservoir simulation studies to be used in uncertainty analysis on a Coalbed Methane CBM reservoir. This technique uses Arti cial Neural Networks ANN in order to build a Surrogate Reservoir Model SRM. An SRM is a replica of the full- eld reservoir model that mimics the behavior of the reservoir. A small number of realizations of the reservoir are required to develop the SRM. This is a key di erence between the SRM technique and other techniques in the literature, such as developing a Response Surface Model using Experimental Design technique or using Reduced Models. Once trained, SRMs can make thousands of simulation runs in a matter of seconds. The high speed of the SRM enables the engineer to exhaustively explore the solution space and perform uncertainty analysis. During the development process of SRM, Key Performance Indicators KPIs are identi ed. KPIs are the reservoir parameters that have the most in uence on the desired objective of the simulation study.

The production and transportation of petroleum uids will be severely a ected by the deposition of suspended particles i.e. asphaltenes, diamondoids, paran/wax, sand, etc. in petroleum uid production wells and/or transfer pipelines. In certain instances, the amount of precipitation is rather large causing complete fouling of these conduits. Therefore, it is important to understand the behavior of suspended particles during petroleum uid ow conditions. In this paper, we present an analytical model for the prefouling behavior of suspended particles corresponding to petroleum uids production conditions. We predict the rate of particle deposition during various turbulent ow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of owing conduits. The developed model accounts for the eddy di usivity and Brownian di usivity as well as for inertial e ects. The analysis presented in this paper shows that rates of particle deposition during petroleum uid production on the walls of the owing channel due solely to di usional e ects are small. It is also shown that deposition rates decrease with increasing particle size. However, when the process is momentum controlled large particle sizes, higher deposition rates are expected.

Hostile oil eld corrosive environments have challenged the production and transportation operations of the petroleum industry. The estimated cost of corrosion on the U.S. economy in the year 2002 resulted in an expenditure of about 276 billion U.S. dollars. This amount was an increase of more than $100 billion over a previous ve year period. Corrosion maintenance expenditures over this 5 year period were approximately 3.1% of the U.S. GDP, and stimulated congress to enact the Corrosion Prevention Act in 2007. One avenue available to successfully combat corrosion in the petroleum industry is the recent progress made in corrosion prediction applications for petroleum operations. Three such corrosion computer models have been developed at the University of Louisiana at Lafayette. These models are capable of predicting the physical conditions and corrosion rates inside pipelines and in producing oil and gas wells. The models are window based and described in this paper. An expert system module was developed, which adjusts the predicated corrosion rate based on various known reservoir and well subsurface parameters.

A statistics based design of experiments Central Composite Design, CCD was used in the present work to develop an empirical model for describing, quantitatively, the methanolysis reaction of canola oil by the commercially immobilized Candida antarctica lipase, i.e. Novozym 435 in a solvent-free system. The reaction factors under study were the amount of enzyme x1, temperature of operation x2 and the molar ratio of methanol to canola oil x3. The yield of methyl ester was evaluated using a second-order polynomial multiple regression model. An analysis of variance ANOVA showed a high coe cient of determination R2 value of 0.987, thus, ensuring a satisfactory adjustment of the regression model with the experimental data. The positive sign for the coe cients of the amount of enzyme and the temperature of the reaction indicated that the yield of the methyl ester increased with increased levels of x1 from 3 to 5 and factor x2 from 25 to 35 C. The negative e ect of the methanol to canola oil ratio on the methyl ester yield indicated that the response level decreased as this factor x3 increased. The methyl ester yield, 84.42%, as the highest value obtained through experiment that was in agreement with the predicted yield 89.15%, resulted with use of the optimized operative parameters when enzyme amount, reaction temperature and methanol to canola oil molar ratio were 5%, 38 C and 3, respectively.

The synthesis of amoxicillin with immobilized penicillin G acylase PGA in aqueous medium was investigated. The parameters studied were: time course of amoxicillin production, concentration of substrates: hydroxyphenylglycine methyl ester HPGM and 6-aminopeicillanic acid 6- APA and the e ect of enzyme PGA content and pH, under variable and constant conditions and temperature variations. In the study of two substrate concentration on amoxicillin production, impressive results were obtained for a 1/3 ratio of 6-amino penicillanic acid 6-APA and hydroxyl-phenylglycine methyl ester HPGM. The synthesis of amoxicillin was preferable at constant pH rather than a variable one. Other optimal conditions obtained were: enzyme concentration: 5 g/L with 100U, process time: 480 min and temperature: 35 C. The yield for amoxicillin synthesis under prescribed conditions showed up to 50%.