جستجوی مقالات مرتبط با کلیدواژه « اسید استیک » در نشریات گروه « فنی و مهندسی »

dioxide has been considered by the process of cyclic surface adsorption using calcium-based adsorbents. Despite a proper performance, the reduction of adsorption capacity due to the sintering of Ca-based adsorbents with increasing number of cycles is still a big challenge. In this study, the performance of two Ca-based adsorbents prepared from lime ore (limestone) and eggshell sources in terms of adsorption capacity during 20 consecutive carbonation and calcination cycles was investigated. Then, in order to overcome the sintering problem, both limestone and eggshell adsorbents were treated with acetic acid at a concentration of 10% by volume. The results showed that the presence of acetic acid in both types of adsorbents led to an increase in the effective conversion at the end of 20th cycle, so that the values of 0.38 and 0.33 were obtained for limestone and eggshell with 10% v/v acetic acid, respectively, which was comparable to the corresponding values for raw limestone and eggshell (in the absence of acetic acid), that is 0.24 and 0.20. The reason for the increase in the conversion by treating with acetic acid can be attributed to the formation of calcium acetate, which has led to the formation of more porous and stable structures. By comparing the two calcium sources used in this study, it was found that limestone has a better performance than eggshell in terms of CO2 adsorption capacity, so that the conversion rate of raw limestone was 1.2 times higher than raw eggshell, which could be related to its high purity as well as its larger crystal size compared to eggshell.

Using of chitosan biopolymer has been developed in the form of edible film and coating as a packaging material for food products. The physical and mechanical properties of chitosan film are influenced by various factors. To investigate the impact of effective factors on the film-forming solution, the present experiment in a completely randomized design using the 23 factorial method, a total of 8 treatments including the level (2 and 4%), molecular weight (high and low) of chitosan and solvent type (acetic acid and citric acid) used in film preparation was carried out. The physical and mechanical parameters of the films were measured. Also, the microstructure of the films was investigated using scanning electron microscope (SEM) images and infrared spectroscopy (FTIR) spectra. The results showed that 4% high and low molecular weights chitosan films which were dissolved in the acetic acid had the highest tensile strength (0.16 ± 0.01 MPa), Young's modulus (2.45 ± 0.55 MPa) and impermeability (2.17 ± 0.09 ± 0.09 g/msPa), and the highest elongation at break (54.33% ± 0.95%) was observed in 4% high molecular weight chitosan film with citric acid solvent (p<0.05). In addition, high molecular weight chitosan film dissolved in acetic acid was more transparent compared to citric acid (p<0.05). SEM images and IR spectra analysis confirmed the obtained results. Therefore, the physical and mechanical performance of the chitosan film was affected by the level and molecular weight of chitosan, and especially the type of acidic solvent, as well as the interaction effects of these factors. In general, the use of a higher level and molecular weight of chitosan leads to the production of a better film, and acetic acid is a more suitable solvent than citric acid.

Oxidative Desulfurization of untreated kerosene with sulfur content of 0.3% with mixture of hydrogen peroxide / acetic acid or formic acid was studied. The effects of operating parameters such as temperature, reaction time, molar ratio: of oxidant to sulfur (no / ns), and acid to sulfur (nacid / ns) on desulfurization were checked. results showed that the optimal conditions for the removal of sulfur from kerosene is 96% with formic acid oxidation systems and is 94% with acetic acid and sulfur are reminded in order of 114 ppm and 191 ppm respectively. Optimization of operating parameters on the reaction have the following 30 min reaction time, temperature 60 0C, oxidant molar ratio to sulfur 25 and acid molar ratio to sulfur 60. The results shows that with increasing reaction temperature and increasing the value of molars ratio (no / ns,15-40) and (n acid / ns,20-80) desulfurization increased.

In this paper, the kinetic of methanol carbonylation by homogeneous Iridium catalyst with present of CH3I as promoter in acid media, has been studied. The reaction was carried out in liquid media with constant carbon monoxide pressure (22-40 atm) and temperatures of 170, 185, 195 °C. The effect of carbon monoxide partial pressure and methyl iodide promoter, acetate methyl, water and Iridium catalysts concentration on the reaction rate have been investigated. It was found that the reaction rate is dependent on the initial reactant concentrations and CO partial pressure. Based on the Arrhenius formula, the activation energy and frequency factor were calculated.

The most important objectives of the development of a new process for synthesis of acetic acid are reducing raw material consumption, energy requirements, and investment costs. Different methods have been presented for synthesis of acetic acid in literature but industrial processes for the production this petrochemical intermediate are dominated by methanol carbonylation and the oxidation of hydrocarbons such as acetaldehyde, ethylene, n-butane, and naphtha. In addition of comparison synthesis methods, application of the product is investigated and advantages of the methods have been presented. In this regard, proper process for production of acetic acid can be selected. Finally results show that methanol carbonylation method is proper because of high purity, low production cost, reaction condition, yield and also no undesired byproducts as the best choice for acetic acid production.