Journal of Applied Research in Chemistry
Year:2014 | Volume:7 | Issue:4|Papers Count:10

The main objective of this research was to model an industrial hydrogen plant based on steam methane reforming using artificial neural network (ANN). Two different ANN networks were developed for prediction of hydrogen production rate and corresponding energy consumption using 20 operating parameters as inputs of both networks. The obtained ANN resuls indicated a very close compatibility with average absolute error, average relative error, and probable error of 2.14, 1.21, and 2.9 for hydrogen production, 0.37, 0.84 and 0.55 for energy consumption, respectively. Based on sensitivity analysis, temperature of synthesized gas from reformer was identified as the most important parameter influencing the hydrogen production, and energy consumption was affected the most by the tail gas flow rate. After ANN modeling, genetic algorithm (GA) was used to optimize plant operating conditions. In this regard, plant gross profit was considered as objective function and GA optimization resulted in the profit of $42.56/h which is 25% higher than actual average profit.

Recently, the powerful waves of ultrasound are used in the polymerization reactions in the absence of initiator. Hydrogel formation by ultrasonic waves is possible just in viscous mediums, such as glycerol. In this study, hydrogels were obtained from the water-soluble acrylic monomers and methylene bis-acrylamide crosslinker in water/glycerol medium. All studies were done at constant temperature of 37 oC, the human body temperature. Ultrasonic irradiation eliminates the need of heating and initiator and reduces the formation time to a few minutes. In addition, hydrogels synthesized by ultrasound have uniform microscopic structure and high swelling capacity. SEM images of the obtained samples are consistent with nanostructure having many tiny pores. Results show that changing environment changes the viscosity of the reaction and so the reaction time and rate. However, the reaction is not significantly affected by ionic strength and acidity. An increase in ultrasonic power and pulse reduces reaction time. In this way we can build and control the synthesis reaction -rate and structure- of biomaterials and living systems, including drug delivery.

In this paper a simple and efficient technique based on a special format of dispersive liquid–liquid microextraction for extraction/preconcentration of benzene, ethyl benzene, toluene, and xylene isomers (BTEX) from juices has been developed. The extraction method was performed in a narrow-bore tube containing the sample. The extract was then injected into a gas chromatography instrument and quantified against standard solutions. The effect of parameters influencing extraction, such as type and volume of disperser and extraction solvents, sample volume, pH, and ionic strength of the sample solution were evaluated and optimized. Under optimized conditions, the proposed technique showed a linear calibration curve between 6 to 700 mg.L-1 with a correlation coefficient of 0.96, relative standard deviation less than 4.5%, and recoveries between 96.2 to 101.0%. Limit of detection and limit of quantification were calculated to be 1.5-2.2 and 5.0-7.3 mg.L-1, respectively. Enrichment factors were in the range 31-173 folds. Finally in order to evaluate the applicability of the suggested method, it was successfully applied for the analysis of these compounds in a few fruit juices.

In this paper, because of the effect of micro structural formula of rubber compounds on their viscoelastic properties, diversity of the microstructure and the crosslinking percentage type of (C-C) of Poly Butadiene elastomer were considered using ATR FT-IR spectroscopy. The rheometeric results show that as the gel percentage of poly-butadiene elastomer increases, the amount of MH-ML, torque, optimum cured time, and scorch time will decrease. Also, it was found that increasing the gel content in poly butadiene causes reduction of the mechanical properties of samples such as fatigue life, modulus100%, modulus 300%, abrasion resistance and tensile strength, but increase in elongation at break and strain of samples.

International reserves of medium and light oils are in decline while extra-heavy crude oil exploration and exploitation increase significantly. Furthermore, the recent strength and stability of crude oil prices and advances in refining technology have raised the prospect of a major expansion in upgrading non-conventional extra-heavy crude oil resources. In this work, attempts were made to use technical grade sodium molybdate as an inexpensive and available catalyst for upgrading a heavy feedstock i.e., 350+ cut of an Iranian extra-heavy crude oil. To do such a task, performance tests were carried out in an autoclave with the volume of one liter under the following conditions: pressure of 70 bar, temperature of 440oC, H2/HC molar ratio of 1200, and the residence time of 20 min. Results showed that after using the technical grade sodium molybdate without any pre-processing, the conversion of upgrading was approximately the same as the commercial catalyst i.e., ammonium molybdate (about 50%). But, in comparison to that, the coke formation was enhanced from 0.05wt% to 0.2wt% of the heavy feedstock.

The catalytic performance of tungstophosphoric acid hydrate H3 [PW12O40] (HPA) was evaluated in the condensation reaction of Meldrum's acid with aldehydes, ethylacetoacetate, and ammonium acetate to yield the corresponding 2-methyl-6-oxo-4-aryl-1, 4, 5, 6-tetrahydropyridine-3-carboxylates. This procedure presents a simple, rapid, and efficient one-pot method for the preparation of these Hantzsch-like products. The procedure takes place at 80oC in water, which is an environmentally benign medium, and gives good to excellent yields in short reaction times.

In this study, removal of an azo dye, Acid Red 206, from an aqueous solution by biosorption on dead fungus, Irepex lacteus, was investigated. Effect of initial pH of the dye solution, initial concentration of dye and temperature on the amount of adsorption were investigated. The maximum adsorption occurred in pH=3, initial concentration of dye=150 ppm and temperature=20oC.The experimental results show that Pseudo-first-order kinetic models, and Fritz, and Schlunder isotherm model are suitable for absorption of this dye.

Molybdenum sulfide has a wide range of applications and is the most important solid lubricant. It is proved that lubricant properties are enhanced in nanoscale. Therefore, the synthesis of nano molybdenum sulfide is attractive. Performance of mineral additives in lubricants depends on their dispersibility in oil and thus the surface of minerals must be coated with organic compounds. In this article, synthesis of coated molybdenum sulfide nanoparticles under simple and mild reaction conditions, using Na2MoO4 and Na2S in the presence of pyridinium dialkyl dithiophosphate as the coating agent, is reported. Physical properties such as particle size and morphology were determined by analytical methods (TEM and XRD). Particle diameter was in the range of 20 to 40 nm with a spherical morphology. Dispersibility of the synthesized nanoparticle in base oil is also investigated.