JOURNAL OF SEPARATION SCIENCE AND ENGINEERING
Year:2015 | Volume:7 | Issue:2|Papers Count:8

Bioethanol is a second generation biofuel that has recently received attention due to limited fossil fuel resources and air pollution cause of fossil fuels. In this study production of bioethanol from lignocellulosic material of corn fiber in a membrane bioreactor was investigated. Acid pretreatment was used to increase the fraction of cellulose to 41%. The strain of saccharomyces cerevisiae was used as yeast. In most previous works the experimens have been performed in batch systems, whereas in this study simultaneous saccharification and fermentation (SSF) were performed in a continuous ultrafilteration membrane reactor, where the product is removed to prevent the inhibitory effect of the product on bioethanol production yield and enzyme deactivation. Experimental design and optimization was carried out by Design Expert software. The optimum conditions were determined to be: temperature (38.5°C), agitation speed (631.2 rpm) and surfactant concentration (0.08%v/v). Under these conditions the predicted ethanol yield was 87.8% and the actual experimental value was 84.2%.

Packed columns are important parts of mass and heat transfer equipments, Nowadays, using packed columns is increasing due to lower pressure drop, higher capacity and mass transfer compared with tray columns.In this survey, parameters affecting column performance were measured, these include: liquid hold up and gas-phase mass transfer coefficient in a humidification column using random packing in towers with 0.1 m and 0.2 m diameters and 1m height. In these experiments, liquid and gas phase were water and air, respectively. Air velocity was between 1.32 to 3.92 (m3/hr) and liquid velocity was between 10 and 70 (m3/hr). In this paper, Nakajima model was used to predict the effective area. Experimental data of gas-phase mass transfer coefficient was compared with Zech, Shi, Grouff, Shulman, Billet and Onda models. Average relative errors were 7%, 15%, 29%, 21%, 45% and 195%, respectively. To predict mass transfer coefficients, Zech model was more accurate Also, by decreasing diameter of tower, gas-phase mass transfer coefficient (Kg.ae) increased.

Nowadays, we can reduce the latent load of the system with using desiccant as an absorbent in air conditioning and cooling systems. In this research the operation of lithium bromide liquid desiccant in air dehumidification process is investigated with using experimental design of a central composite design of response surface methodology. The effect of four input factors including air inlet humidity and temperature, desiccant concentration and mass flow rate ratio of desiccant solution to the air as a response is investigated. The air and desiccant outlet temperature and dehumidification mass rate is expressed as a function of input parameters with a reduced quadratic equation and the model has shown good agreement with experimental data. The optimum conditions showed that using a desiccant solution with concentration of 50%, mass flow rate ratio of 2.4, air inlet temperature of 28.8 (oC) and air inlet humidity of 0.0190 (kgw/kgda) maximize the dehumidification mass rate and minimize the air and desiccant outlet temperature.

In this study, separation of styrene and ethyl benzene from petrochemical wastewater using membrane bioreactor was investigated. The results showed that the removal efficiency of chemical oxygen demand (COD), styrene and ethyl benzene in the hydraulic retention time (HRT) of 20 hours were 98, 99 and 99%, respectively. With reducing HRT to 15 hours, COD removal efficiency did not change and styrene and ethyl benzene removal efficiency through stripping decreased about 0.4%. On the other hand, it was indicated that existing ethyl benzene could have a negative effect on styrene removal. Also, results show that due to decreasing sludge particle size and increasing soluble microbial product (SMP), trans membrane pressure (TMP) changes rate increased at 15 hour compared to 20 hours. Further, changes of EPS for mixed liquor showed that EPS concentration decreased with decreasing HRT.

In this research, carbon dioxide reactive absorption process in ammonia and sodium hydroxide solution was modeled and simulated. Rate based model with unsteady state film model was used in the process modeling considering two mass transfer directions. The model equations including a set of ordinary and partial differential equations were solved simultaneously using finite difference and method of lines. Simulation of the process was carried out using different stage numbers. Experimental data form absorption pilot plant was used for evaluation of the process simulation. The simulation with 60 stages has 4.36 percent minimum devotion. On the other hand, result from rate base model was compared with enhancement factor method. The results showed that simulation results were more accurate when rate based model has been used.

Multi Criteria Decision Making (MCDM) is a suitable approach for optimizing non-linear processes. Considering various effective variables, these methods usually improve process and non-process efficiency and reduce capital and operating costs of industrial units. In this study, three coal processing circuit options including Heavy Medium Cyclone (HMC), Tri-Flow (TF) and the combined process of Tri-Flow and Bioheap leaching (CTBL) were compared to select the most suitable process for treating Tabas coarse-coals. Some critical parameters namely environmental advantages, circuit simplicity, equipment availability, capital cost, operating cost and income per ton of coal feed were chosen and weighted based on expert point of view and previous investigations. Regarding to qualitative nature of the selected criteria and their associated uncertainty, fuzzy TOPSIS multi-criteria decision-making method was used to evaluate the proposed options. It was found that the highest (0.336) and lowest (0.225) closeness coefficients for the wash ability of high sulfur coarse coals of Tabas were related to the CTBL and the HMC circuits, respectively.

Replacing toxic antifouling paints with coatings that have no effect on the marine environment is an important issue. Phenazine 1-carboxylic acid (PCA) is one of the effective antibiotics, which can be used as antifouling agent in marine coatings to prevent attachment of marine species on ship hulls. In this study, Phenazine 1-carboxylic acid (PCA) as an antibacterial agent which produced by Pseudomonas Aeruginosa MUT.3 was investigated. PCA extraction process was optimized using Response Surface Methodology (RSM). Results showed that at 30 min mixing time, 150% of solvent and using ethyl acetate as solvent are considered the optimum levels and factors in phenazine 1-carboxylic acid production which produced by P. aeruginosa MUT.3. In the present paper, the optimization of extraction process suggested as an effective way to increase the production in biological processes in which the extraction of PCA increased by 34% compared to previous reports.

The numerous applications and high cost of platinum group metals (PGMs), in addition to the scarcity of their sources and mines, has led the secondary sources of these metals to a high consideration. In this study, the hydrometallurgical recovery of platinum from spent catalysts was investigated. For this purpose, after the preparation and grinding, the catalysts were dissolved in HCl and HNO3, as an oxidant. Extraction of platinum from acidic solution was performed by magnetite nanoparticles. Firstly, the magnetite nanoparticles were synthesized by co-precipitation of ferrous and ferric salts in the presence of ammonium hydroxide. Because of the instability and tendency to agglomeration, the surface of nanoparticles was coated by tetraethyl silicate. Subsequently, the silica-coated nanoparticles were functionalized with diphenyl phosphine ligand, that had the ability to selective adsorption of Pt. Finally, in a time less than 15 minutes about 91% [PtCl4] 2- was recovered from leach liquor.