SCIENTIA IRANICA
Year:2011 | Volume:18 | Issue:3 (TRANSACTIONS C: CHEMISTRY AND CHEMICAL ENGINEERING)|Papers Count:12

An efficient and simple new method for the preparation of 1-amidoalkyl-2-naphthols as biologically interesting compounds is described. The one-pot multi-component condensation of b-naphthol, aromatic aldehydes and acetamide/urea in ionic liquid 1-butyl-3-methylimidazolium bromide ([Bmim] Br) under microwave and catalyst-free conditions affords the title compounds at high yields and in short reaction times.

An efficient method for synthesis of hydrophobically modified starch without using organic solvents is described. The esterification of starch was performed with long chain fatty acid chlorides (C8, C12, C16), in two steps. In the first step, native starch was dispersed in an alkali reaction medium, and in the second step, it was treated for esterification. Finally, hydrophobic starch esters were obtained with moderate degrees of substitution (DS-values<0.45). The reactivity of corn and potato starches under the same reaction conditions was also studied. The chemical structural determinations of the obtained products were investigated using common spectroscopy methods, such as FTIR and 1H NMR spectra. Starch nanoparticles and nanodispersion solutions were prepared via a dialysis method. The particle size distribution of the nanoparticles was determined using a laser diffraction particle size analyzer in an aqueous dispersion. The morphology investigation of the starch and the grafted starch nanoparticles was performed using SEM after freeze drying.

Amino functional mesoporous silica SBA-15 materials have been prepared as efficient adsorbents for halophenols in wastewater. The organic–inorganic hybrid material was obtained using successive grafting procedures of SBA-15 silica with 3-aminopropyl-trimethoxysilane (NH2–SBA-15). The comparison of adsorption of halophenols on untreated mesoporous SBA-15 and NH2–SBA-15 is studied. It is found that NH2–SBA-15 shows significant adsorption for halophenols. The samples were characterized by X-Ray Diffraction (XRD), nitrogen adsorption-desorption isotherms, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FT–IR). Batch adsorption studies have been carried out to study the effect of various parameters, such as contact time, pH, adsorbent dose and initial adsorbate concentration. The equilibrium adsorption data of halophenols onto NH2–SBA-15 were analyzed using Freundlich and Langmuir adsorption isotherms. From the sorption studies it was observed that the uptake of 4-chlorophenol (CP) was higher than 4-bromophenol (BP) and 4-iodophenol (IP).

An efficient and simple method for the synthesis of biologically active 14-aryl-14H-dibenzo [a, j] xanthenes has been achieved through a one-pot condensation of aryl aldehydes and b-naphthol under solvent-free conditions in the presence of Sulfonic acid functionalized silica (SiO2-Pr-SO3H), as an efficient heterogeneous solid acid catalyst with excellent yields and short reaction time.

The kinetics of side reactions in the dehydrogenation of propane over a supported platinum catalyst modified by tin, were investigated. Catalytic dehydrogenation over a commercial Pt-Sn/g -Al2O3 was carried out in a laboratory-scale plug-flow reactor at 580–620oC under atmospheric pressure. Several kinetic models derived from different reaction mechanisms were tested using experimental data obtained under a range of reaction conditions. It was found that the kinetics of the main dehydrogenation reaction was best described in terms of a Langmuir–Hinshelwood mechanism, where the adsorption of propane was the rate controlling step. Simple power low rate expressions were used to express the kinetics of side reactions.

In this study the kinetic modeling of visbreaking reactions for a number of vacuum residue feeds was investigated using available experimental data from the literature. A continuous lumping model was developed for kinetic analysis of visbreaking reactions. The normalized boiling point was used to describe each feed as a continuous mixture and the concentration distribution of the mixture would change under reaction conditions. A continuous model with five adjustable parameters was used to describe visbreaking reactions, and these parameters were optimized for each feed for reaction temperatures in the range of 400–430oC using available experimental data. The model was able to accurately predict the weight percent of each boiling cut in the reaction products.

Fuzzy set theory models situations in which the uncertainty is due to the non-precise (fuzzy) environment. One such case is testing the hypotheses problem where hypotheses are fuzzy rather than crisp and the data are crisp. Pais and Benton (1997) [1] present a suitable amount of cadmium absorption which is more appropriate for modeling by a fuzzy subset. In this paper, on real-world agricultural data generated by Ivani (2007) [2], the suitableness of the mean absorption cadmium in the plant from the polluted soil is tested at the given significance level. Due to uncertainty in the suitable amount of cadmium absorption, in order to test this amount, we use fuzzy hypotheses testing instead of classical hypotheses testing. The fuzzy p-value approach is used for this test to conclude whether or not the mean absorption of cadmium coincides with the proposed amounts by Pais and Benton [1]. As expected, in fuzzy hypotheses testing, the degree of acceptance or rejection of the null fuzzy hypothesis is computed for each treatment of pollution. The data are from two plants: radish and cress, which are experimented on in soil polluted with CdNO3 salt. The results showed that using classical hypotheses testing may lead to contradictory decisions, and the proposed fuzzy hypotheses testing is a rational substitute for classical hypotheses testing when the environment is in a vague status.

Highly active unsupported MoO3 and Co - MoO3 catalysts were prepared by a simple solution reaction method in the presence of different organic additives. Catalysts were characterized by the XRD, BET surface area measurement, SEM and TEM techniques. Results suggested that utilizing different additives produced different morphologies of MoO3 microstructures. Optimizing reaction conditions was found to produce more active molybdenum oxide nanoparticles when urea and PEG200 additives were utilized. XRD and TEM results indicated crystal growth restriction after cobalt incorporation. Catalytic activities of prepared materials were evaluated in the hydrodesulfurization reaction of Naphtha. Products were analyzed by XRF to determine the residual sulfur content of the feed after the reaction occurred.It was concluded that nanostructures and promoted catalysts had higher activities than microstructure samples. Ultimately, the reaction over the urea-prepared promoted catalyst decreased the sulfur content of the feed of Naphtha from 2420 to 24 ppm, which is considerably lower than that of commercial catalysts.

To possibly help in understanding the chemistry of the D process using E. urophylla × E. grandis LH 107 as the pulping material, residual lignin in kraft-oxygen pulp bleached by chlorine dioxide was extracted by the dioxane/water acidolysis method. The content of functional groups in the extracted lignin was determined by 13C and 31P NMR spectroscopy. A relatively significant difference could be seen in the chemical properties of residual lignin between oxygen delignified (O) and chlorine dioxide treated (OD) pulp. The results suggest a decreased function group content in the residual lignin of chlorine dioxide treated kraft-oxygen pulps. It is quite interesting that the depletion of phenolic hydroxyl and methoxyl group present in residual lignin is due to the quinone formation during the oxidation of chlorine dioxide, based on the data obtained in HSQC and 13C NMR spectra of non-cyclic and cyclic MATS, and the content in condensed and unsubstituted phenolics is reduced to the same degree, which is contrary to what we generally perceive

Techniques of production data analysis for single-phase oil and gas reservoirs have advanced significantly over the past few years. These techniques range from traditional (Arps and Fetkovich) to modern (for the variation of operating conditions at the wellbore). The application of these techniques for analysis of the production data of a gas condensate reservoir may not yield reliable answers due to the fact that the flow of fluid in gas condensate reservoirs is not single-phase. This paper presents the treatment of a modern method of production data analysis (single-phase flow) to analyze the production data of a gas condensate reservoir (two-phase flow). For this purpose, a single-phase production model is presented. Using a compositional reservoir simulator, long-term production data is generated over a wide range of gas condensate reservoir parameters. Next, a comparison is made between the simulator results (gas condensate) and the corresponding single-phase gas reservoir, using a modern production analysis method. The error for each case is analyzed, and a correlation for treatment of the single-phase analysis method is developed. Our results show that the methodology developed here can be successfully applied for analysis of the production data of a gas condensate reservoir.

This study was focused on the heavy metal (Ni, Co, Mo, V, Mn, Fe, W and Zn) tolerance of fungi strains Aspergillus niger, Aspergillus foetidus and Penicillium simplicissimum. Aspergillus niger was exposed to a mixture of Mo, V and Mn at a mass ratio of 1: 2: 6 as approximately present in the spent refinery processing catalyst. This study highlights the adaptation of fungi strains to Tungsten and Vanadium to high concentration. The effect of different metals and metal concentration on different strains of fungi was evaluated. Results showed that Ni was one of the most toxic metals for strains of Aspergillus and Penicillium. Aspergillus foetiduswas the least tolerant, in particular for Ni, Co and Zn. In this work, Aspergillus niger, Aspergillus foetidusand Penicillium simplicissimum showed higher tolerance towards Mo and V, and the three fungi have a good potential for the bioleaching of spent refinery processing catalysts that contain Mo and V. The main objective of this study is to identify the best strain, based on tolerance development, for the spent refinery processing catalyst.

Simulation of the in-situ combustion process is one of the most complex simulations amongst other reservoir flow simulations. Accurate simulation of the process is critical to obtain a successful implementation of the in-situ combustion process. Several factors impact performance of the simulation of this process. First are all the numerical models used for different sub-processes, such as reactions, fluid phase behavior, heat loss to surrounding formations and fluid physical properties. In the previous numerical models of the in-situ combustion process, very simplified models were used for the phase behavior of the fluid. Recent studies show that the fluid phase behavior model has a great effect on the results of the simulation. In this work, a novel simulator is presented, which uses a rigorous phase equilibrium model for fluid phase behavior calculations. The numerical model is developed in such a way that different models for the phenomena mentioned above can be replaced easily. The other affecting parameter is the solution scheme of the simulator. Previous studies indicated that the more implicit the solution scheme, the better the performance of the simulator. The presented simulator uses a full implicit solution scheme to solve the equations. The applicability of this method is examined through two synthetic reservoirs.