BRTeam`s Latest Publication
Mohammad Mahdi A. Shirazi, Ali Kargari, Meisam Tabatabaei, Bouck Mostafaei, Mandana Akia, Mohammad Barkhi, Mohammad Javad A. Shirazi. 2013. Acceleration of biodiesel-glycerol decantation through NaCl-assisted gravitational settling: A strategy to economize biodiesel production. (Bioresource Technology)– (ISI-Scopus cited). (5-Year Impact Factor: 5.352). Elsevier
When making biodiesel, slow separation of glycerol; the main by-product of the transesterification reaction, could lead to longer operating times, bigger equipment and larger amount of steel and consequently increased production cost. Therefore, acceleration of glycerol/biodiesel decantation could play an important role in the overall biodiesel refinery process. In this work, NaCl-assisted gravitational settling was considered as an economizing strategy. The results obtained indicated that the addition of conventional NaCl salt decreased the glycerol settling time significantly up to more than 5 times. However, NaCl inclusion rates of more than 3 g to the mixture (i.e. 5 and 10 g) resulted in significantly less methyl ester purity due to the occurrence of miniemulsion phenomenon. Overall, addition of 1 g NaCl/100 ml glycerol-biodiesel mixture was found as optimal by accelerating the decantation process by 100% while maintaining the methyl ester purity as high as the control (0 g NaCl).
Mohammad Mahdi A. Shirazi, Dariush Bastani, Ali Kargari, Meisam Tabatabaei. 2013. Characterization of polymeric membranes for membrane distillation using atomic force microscopy. (Desalination and Water Treatment)– (ISI-Scopus cited). (5-Year Impact Factor: 0.752). Taylor & Francis
As membrane distillation (MD) is an under-developed separation process, specific membranes for MD applications are not yet commercially available. Therefore, microporous polymeric membranes made of hydrophobic materials fabricated for microfiltration purposes are usually used for MD applications. Characterization of such kind of membranes is important in order to achieve a better in-depth understanding of their performance and to fabricate specific membranes for MD process. One of the emerging characterization methods is atomic force microscopy (AFM) analysis. AFM is a newly developed high-resolution method that is useful for studying the surface topography of various types of membranes, and 3D images of the membrane surface can be obtained directly without special sample preparation. Consequently, a truer and clearer surface structure of a polymeric membrane can be observed. In this work, AFM method has been used for characterization of three hydrophobic membranes (polytetrafluoroethylene, polypropylene, and polyvinylidene fluoride) which are typically used for various MD applications. The membranes were characterized for their pore size, pore size distribution, surface roughness, and hydrophobicity. A sweeping gas membrane distillation apparatus was used for solute rejection evaluation of the applied membranes.
Ahmad Farhad Talebi, Masoud Tohidfar, Meisam Tabatabaei, Abdolreza Bagheri, Motahhareh Mohsenpor, Seyed Kaveh Mohtashami. 2013. Genetic manipulation, a feasible tool to enhance unique characteristic of Chlorella vulgaris as a feedstock for biodiesel production. (Molecular Biology Report)– (ISI-Scopus cited). (5-Year Impact Factor: 2.929). Elsevier
Developing a reliable technique to transform unicellular green algae, Chlorella vulgaris, could boost potentials of using microalgae feedstock in variety of applications such as biodiesel production. Volumetric lipid productivity (VLP) is a suitable variable for evaluating potential of algal species. In the present study, the highest VLP level was recorded for C. vulgaris (79.08 mg l-1day-1) followed by 3 other strains studied C. emersonii, C. protothecoides, and C. salina by 54.41, 45 and 18.22 mg l-1day-1, respectively. Having considered the high productivity of C. vulgaris, it was selected for the preliminary transformation experiment through micro-particle bombardment. Plasmid pBI121, bearing the reporter gene under the control of CaMV 35S promoter and the kanamycin marker gene, was used in cells bombardment. Primary selection was done on a medium supplemented by 50 mg l-1 kanamycin. After several passages, the survived cells were PCR-tested to confirm the stability of transformation and then were found to exhibit B-glucuronidase (GUS) activity in comparison with the control cells. Southern hybridization of npt II probe with genomic DNA revealed stable integration of the cassette in three different positions in the genome. The whole process was successfully implemented as a pre-step to transform the algal cells by genes involved in lipid production pathway which will be carried out in our future studies.
Pouya Mohammadi, Meisam Tabatabaei, Ali M. Nikbakht, Khalil Farhadi, Mehdi Khatami far, Marco Castaldi. Simultaneous energy recovery from waste polymers in biodiesel and improving fuel properties. (Waste and Biomass Valorization)– (ISI-Scopus cited). (Unofficial Impact Factor: 1.47). Springer
Although biodiesel has been known as an alternative fuel with specific advantages, it has also been investigated as a bio-solvent. In this study, biodiesel was applied as a bio-solvent for expanded polystyrene (EPS) and the kinetics of polymers' dissolution in biodiesel was also investigated. Physicochemical parameters such as solubility parameters of EPS and biodiesel as well as polymer-solvent interaction were calculated at 21.13, 18.19 (MPa)1/2 and 0.343, respectively. From the energy recovery point of view, different parameters i.e. flash point, density, kinematic viscosity and dynamic viscosity were evaluated for the waste polymer-biodiesel blended diesel fuel. The results obtained revealed that the addition of EPS improved the biodiesel blended diesel fuel by increasing the flash point value while reducing the density and viscosity values. Moreover, the addition EPS alone generally increased the cloud point values, but co-addition of EPS and co-solvent (acetone) partially restored them to the original values. The overall engine test results were also in favor of the fuel blend as fuel consumption and emissions i.e. CO, CO2, NOx and smoke reduced considerably while the power generated remained approximately constant.
Ahmad Farhad Talebi, Seyed Kaveh Mohtashami, Meisam Tabatabaei, Masoud Tohidfar, Abdolreza Bagheri, Mehrshad Zeinalabedini, Hossein Hadavand, Mehrdad Mirzajanzadeh, Shiva Bakhtiari. 2013. Fatty Acids Profiling; a Selective Criterion for Screening Microalgae Strains for Biodiesel Production. (Algal Research)– (ISI-Scopus cited). (Tracked for Impact Factor). Elsevier
The type and amount of lipids produced by an algal species directly influences the quality of the achieved biodiesel. This study is the first to report on the isolation process and lipid profile analysis of algal strains obtained from the Persian Gulf as well as 9 previously introduced strains. Biomass productivity and lipid productivity seemed to be adequate criteria for estimating the potential of different microalgae species for producing biodiesel. A principal components analysis (PCA) was applied to the estimated properties of biodiesel and the results obtained were plotted against lipid productivity. This led to the distinction of five different microalgae groups in regards to their potential for biodiesel production. This analysis also highlighted the dependence of the fuel properties on oil saturation level. On that basis, Amphora sp. and the two locally isolated strains (Dunaliella sp.) formed the extreme groups. The other three groups generated biodiesel of intermediate quality. The highest volumetric lipid productivity (79.08 mgl -1day-1) was found in Chlorella vulgaris. Based on the results of bioprospection by FAME profiling, the best approach for obtaining quality algal biodiesel is to mix the oils of distinct cell cultures or to specifically select proper microalgal strains for different climate conditions.
Yaghoub Mansourpanah, H. Soltani Afarani, K. Alizadeh, M. Tabatabaei. 2013. Enhancing the performance and antifouling properties of nanoporous PES membranes using microwave-assisted grafting of chitosan (Desalination)– (ISI-Scopus cited). (5-Year Impact Factor: 2.403). Elsevier
In this work, we tried to improve the surface and antifouling properties of polyethersulfone (PES) membranes coated by a thin layer of chitosan. Acrylamide (AAm) as a grafting agent and microwave-assisted grafting as a physical procedure were employed to grafting of the chitosan thin layer without using any chemical initiator. Different acrylamide concentrations (1.8, 3 and 4.2 wt.%), irradiation times (0, 10, 30 and 60 s) as well as irradiation powers (180, 360 and 520 W) were employed. The modified membranes showed an outstanding antifouling property for Bovine Serum Albumin (BSA) in some conditions of preparation. The separation properties of the thin film composite membranes for ion solutions (NaCl, Na2SO4 and MgCl2) increased and changed. Water contact angle measurement, ATR-IR apparatus, SEM, AFM and membrane filtration set-up were used for supporting the results. We used Taguchi designs to analyze many factors with few run.