IRANIAN JOURNAL OF CHEMICAL ENGINEERING
Year:2010 | Volume:7 | Issue:1|Papers Count:7

One limitation in the use of hydrophilic polymers as implantable devices is their inherently poor mechanical strength. Using interpenetrating polymer networks (IPNs) consisting of both hydrophilic and hydrophobic networks is an effective method to strengthen these polymers. In this work, a series of poly(dimethyl siloxane)/ poly(acrylic acid) sequential IPNs was synthesized and the polymerization kinetics of acrylic acid in the presence of ethylene glycol dimethacrylate as the crosslinker was investigated using ampoule polymerization experiments and DSC analysis. The results from conversion measurements revealed the occurrence of gel effect during acrylic acid polymerization. The properties of the produced IPNs including swelling, morphological, and mechanical properties were also investigated.

This article describes kinetic modeling of the reduction of barium sulfate by methane based on experimental data obtained by thermogravimetric technique. The conversiontime data have been interpreted by using the grain model for gas-solid reactions and the effect of catalyst on the kinetic parameters has been elucidated. It was found that zinc oxide acted as a fairly strong catalyst for the reaction, especially at higher temperatures. For example, at about 950°C the reaction rate constant was increased more than 8 times by using only 2 percent of zinc oxide. Orthogonal collocation method was used for solving coupled partial differential equations of gas-solid reaction. There is a good agreement between the experimental data and results obtained from simulation. This research offers a clean method for barium carbonate production with methane as a reducing agent, decreasing CO2 emission significantly. Also, a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving barium sulfide and barium sulfate has been proposed.

The separation of hydrocarbon mixture using facilitated transport membrane (an immobilized liquid membrane type) was investigated. A 50:50 (vol. %) propylenepropane mixture was used as a sample of the hydrocarbon mixture. The effect of transmembrane pressure (in the range of 50-120 kPa) and carrier concentration (in the range of 0-20 wt.% AgNO3) on separation performance was studied experimentally and mathematically. It was observed that increasing trans-membrane pressure and carrier concentration supports the separation factor and propylene permeation rate. On the other hand, increasing trans-membrane pressure and decreasing carrier concentration supports the propane permeation rate. Hence, the greater the trans-membrane pressure and carrier concentration, the more purified the product obtained. It was found that at trans-membrane pressure of 120kPa and carrier concentration of 20wt. %, the highest separation factor (270) and propylene permeation rate (7*10-7mol/s) was obtained. The average deviation between the experimental and modeling results was found to be 5.3% for propylene permeation rate and 0.03% for propane permeation rate.

Silica fume is a by-product of silicon metal or ferrosilicon alloys in smelters using electric arc furnaces. It consists of 85% to 95% amorphous silicon dioxide (SiO2). Each individual particle of silica fume is spherical with average diameter 0.15-0.3mm (100 times finer than cement particle); therefore its specific surface area is high. Silica fume particles are water wet and absorb excess water in cement slurry when cement slurry is extended by water. Silica fume thickens the cement slurry, so rheological properties are controlled by dispersants. In this paper, optimal concentration of silica fume and other additives for preparing 90 pcf cement slurry for liner cementing in one Iranian oilfield is determined. The criteria of designing slurry formulation are slurry density, rheological properties, fluid loss, free water, thickening time of cement slurry, and compressive strength and permeability of set cement. Finally, based on experimental results, the preferable slurry compositions are selected. This formulation can be used for cementing of oil and gas wells where moderate and light weight cement density is needed.

The partition coefficient of guanidine hydrochloride for the PEG4000+ Phosphate + Water system is presented at 298.15 K. The partition coefficient of guanidine hydrochloride was near unity. It was shown that partition coefficient of guanidine hydrochloride was dependent on the concentration of guanidine hydrochloride, pH and PEG/phase forming salt (%w/w) ratio. In most systems the partitioning coefficient of Guanidine is more than one, which means guanidine preferred polymer-rich phase.

At present, gas engineers use the simple Campbell’s equation to determine the proper length of parallel gas pipelines. The Campbell’s equation was proposed for horizontal pipelines with the assumption that the gas compressibility factor and temperature throughout the pipeline are constant. Therefore, the Campbell’s equation has a notable error for an inclined pipeline. In this paper, the Campbell’s equation was extended in a way that it can be used for inclined pipelines. In order to make a comparison between the extended and original equations, a pipeline with different slopes was used. The results show that in the case of using a pipeline with more than 2 degrees in slope, the resultant error is increased to 11 percent by using the original Campbell’s equation. For validation of the extended Campbell’s equation, the results of this equation are compared to the results of HYSYS software (version 3.1) in which the temperature and gas compressibility factor are not considered constant. The results indicate that the average error of the extended equation is less than 2 percent.

Colored wastewater is one of the most important sources of environmental pollution and because of their visibility and bearing toxic chemicals, it is very important to be treated before released into the environment? In recent years, several methods have been used for treatment of dyestuff effluents. In this work, removal of two azo dyes, Acid Orange 7 and Reactive Black 5 as an indicator of synthetic dyes by Fenton-like reaction were studied. In this process, OH0 radicals will be generated by using Fe0 and UV light, so it can occur without the addition of hydrogen peroxide. Various parameters such as pH, amount of iron powder, initial dye concentration, UV light and contact time were studied in terms of their effect on the reaction progress. It is observed that high removal of dyes for UV system was obtained at pH=11, while in the Fe0 and Fe0 /UV system, high removal occurred at pH=3. Removal of dye was increased by increasing the iron mass and contact time. High removal of dye was at the time equivalent of 120 min and reached equilibrium. Initial dye concentration has different effects for Acid Orange 7 and Reactive Black 5 removal. Increasing the initial dye concentration of Acid Orange 7 has increased dye removal in the Fe0 /UV and Fe0 system, while it was decreased in the UV system. For RB5 removal, it was decreased in the Fe0 /UV and Fe0 system by increasing the initial dye concentration, while it increased in UV system.