The Experts below are selected from a list of 14814 Experts worldwide ranked by ideXlab platform
Milda Gumbyte - One of the best experts on this subject based on the ideXlab platform.
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Green algae Ankistrodesmus fusiformis Cell disruption using different modes
Biomass and Bioenergy, 2017Co-Authors: Virginija Skorupskaite, Violeta Makareviciene, Martynas Ubartas, Jurate Karosiene, Milda GumbyteAbstract:Abstract Two different Microalgae Cell disruption modes, ultrasonication (VCX 130 ultrasonic processor and enclosed system) and ultrahomogenization, have been used in this study. The objective of this study was to estimate the efficiency of algae Cell disruption by applying various techniques for disrupting green algae Ankistrodesmus fusiformis and using non-treated and frost-treated algae suspensions. The experiments were carried out using working regimes from 1 to 70 min. The highest efficiency (100%) of Cell disruption was achieved with Microalgae Ankistrodesmus fusiformis using an ultrasonic processor at the following conditions: frozen and defrosted algae suspension; fixed temperature of suspension; processing time – 60 min. Pre-treatment of Microalgae suspension using frost improves disruption effectiveness. Pre-treatment of suspension using frost before mechanical Cell disruption improves efficiency app. from 1 to 12%.
Adam P. Harvey - One of the best experts on this subject based on the ideXlab platform.
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evaluation of fame production from wet marine and freshwater Microalgae by in situ transesterification
Biochemical Engineering Journal, 2013Co-Authors: Sharon B Velasquezorta, Adam P. HarveyAbstract:Abstract In situ transesterification of lipids in algal biomass reduces the number of unit operations by producing alkyl esters (biodiesel) directly from the lipid phase. The production of alkyl esters by in situ transesterification from marine Microalgae Nannochloropsis oculata and freshwater Microalgae Chlorella sp. was evaluated using different catalysts and biomass moistures. Three homogenous catalysts (sulphuric acid, sodium hydroxide and sodium methoxide), and one heterogeneous catalyst (molecular sieve A) were used in Microalgae dried at 0%, 1.5%, and 10% moisture. Maximum lipid conversion was obtained for both, marine and freshwater dried Microalgae using sulphuric acid as catalyst. A FAME yield of 73 ± 5% was achieved from N. oculata at a catalyst:lipid molar ratio of 0.8:1; while 92 ± 2% was obtained from Chlorella sp. at a catalyst:lipid molar ratio of 0.35:1. Differences in FAME yield among Microalgae were analysed in terms of overall Cell structure and biomass salinity. It was observed that Cells of N. oculata were not as easily disrupted as those of Chlorella sp. and that salts present in N. oculata biomass did not affect the acidic transesterification reaction. In conclusion, the acidic in situ transesterification of dried marine or freshwater Microalgae produced the highest conversion; however the yield of alkyl esters was potentially affected by the Microalgae Cell structure and not the salinity of the biomass.
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alkaline in situ transesterification of chlorella vulgaris
Fuel, 2012Co-Authors: Sharon B Velasquezorta, Adam P. HarveyAbstract:Abstract In situ transesterification, or “reactive extraction”, of lipids in algal biomass has the potential to greatly simplify and reduce costs of the production of algal biodiesel, as it reduces the number of unit operations by contacting the biomass directly with the alcohol and catalyst required to convert lipids to their alkyl esters (biodiesel). A design of experiments was conducted to understand the impact of process variables in the production of Fatty Acid Methyl Ester (FAME) from Chlorella vulgaris Microalgae. Three process variables (catalyst ratio, solvent ratio and reaction time) were studied, based on their process significance. The maximum FAME recovery of 77.6 ± 2.3 wt% was obtained at a reaction time of 75 min, using a catalyst:lipid (NaOH) molar ratio of 0.15:1 and a methanol:lipid molar ratio of 600:1. Additional experiments were performed at the optimum methanol ratio (600:1) to compare results obtained using an alkaline catalyst with an acid catalyst. In terms of time, the alkaline catalyst (sodium hydroxide) outperformed the acid catalyst (sulphuric acid) obtaining higher conversions at lower reaction times. Nevertheless, using an acid catalyst ratio of 0.35:1 for longer reaction times resulted in higher conversions, up to 96.8 ± 6.3 wt%, and may have facilitated the breakage of Microalgae Cell walls. In conclusion, the alkaline in situ transesterification of algal biomass can achieve high conversion in less time than an acid catalyst, using a lower ratio of catalyst. The final selection of the type of catalyst will depend on the characteristics (batch vs continuous) and cost of the in situ transesterification including catalyst and methanol costs, and the downstream processes required to obtain a saleable biodiesel.
Virginija Skorupskaite - One of the best experts on this subject based on the ideXlab platform.
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Green algae Ankistrodesmus fusiformis Cell disruption using different modes
Biomass and Bioenergy, 2017Co-Authors: Virginija Skorupskaite, Violeta Makareviciene, Martynas Ubartas, Jurate Karosiene, Milda GumbyteAbstract:Abstract Two different Microalgae Cell disruption modes, ultrasonication (VCX 130 ultrasonic processor and enclosed system) and ultrahomogenization, have been used in this study. The objective of this study was to estimate the efficiency of algae Cell disruption by applying various techniques for disrupting green algae Ankistrodesmus fusiformis and using non-treated and frost-treated algae suspensions. The experiments were carried out using working regimes from 1 to 70 min. The highest efficiency (100%) of Cell disruption was achieved with Microalgae Ankistrodesmus fusiformis using an ultrasonic processor at the following conditions: frozen and defrosted algae suspension; fixed temperature of suspension; processing time – 60 min. Pre-treatment of Microalgae suspension using frost improves disruption effectiveness. Pre-treatment of suspension using frost before mechanical Cell disruption improves efficiency app. from 1 to 12%.
Razif Harun - One of the best experts on this subject based on the ideXlab platform.
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exploring alkaline pre treatment of microalgal biomass for bioethanol production
Applied Energy, 2011Co-Authors: Razif Harun, W S Y Jason, Tamara Cherrington, Michael K DanquahAbstract:We have investigated, for the first time, the alkaline pre-treatment of microalgal biomass, from the species Chlorococcum infusionum, using NaOH for bioethanol production. This pre-treatment step aims to release and breakdown entrapped polysaccharides in the Microalgae Cell walls into fermentable subunits. Three parameters were examined here; the concentration of NaOH, temperature and the pre-treatment time. The bioethanol concentration, glucose concentration and the Cell size were studied in order to determine the effectiveness of the pre-treatment process. Microscopic analysis was performed to confirm Cell rupturing, the highest glucose yield was determined to be 350mg/g, and the maximum bioethanol yield obtained was 0.26g ethanol/g algae using 0.75% (w/v) of NaOH and 120°C for 30min. Overall, the alkaline pre-treatment method proved to be promising option to pre-treat microalgal biomass for bioethanol production.
Sharon B Velasquezorta - One of the best experts on this subject based on the ideXlab platform.
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evaluation of fame production from wet marine and freshwater Microalgae by in situ transesterification
Biochemical Engineering Journal, 2013Co-Authors: Sharon B Velasquezorta, Adam P. HarveyAbstract:Abstract In situ transesterification of lipids in algal biomass reduces the number of unit operations by producing alkyl esters (biodiesel) directly from the lipid phase. The production of alkyl esters by in situ transesterification from marine Microalgae Nannochloropsis oculata and freshwater Microalgae Chlorella sp. was evaluated using different catalysts and biomass moistures. Three homogenous catalysts (sulphuric acid, sodium hydroxide and sodium methoxide), and one heterogeneous catalyst (molecular sieve A) were used in Microalgae dried at 0%, 1.5%, and 10% moisture. Maximum lipid conversion was obtained for both, marine and freshwater dried Microalgae using sulphuric acid as catalyst. A FAME yield of 73 ± 5% was achieved from N. oculata at a catalyst:lipid molar ratio of 0.8:1; while 92 ± 2% was obtained from Chlorella sp. at a catalyst:lipid molar ratio of 0.35:1. Differences in FAME yield among Microalgae were analysed in terms of overall Cell structure and biomass salinity. It was observed that Cells of N. oculata were not as easily disrupted as those of Chlorella sp. and that salts present in N. oculata biomass did not affect the acidic transesterification reaction. In conclusion, the acidic in situ transesterification of dried marine or freshwater Microalgae produced the highest conversion; however the yield of alkyl esters was potentially affected by the Microalgae Cell structure and not the salinity of the biomass.
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alkaline in situ transesterification of chlorella vulgaris
Fuel, 2012Co-Authors: Sharon B Velasquezorta, Adam P. HarveyAbstract:Abstract In situ transesterification, or “reactive extraction”, of lipids in algal biomass has the potential to greatly simplify and reduce costs of the production of algal biodiesel, as it reduces the number of unit operations by contacting the biomass directly with the alcohol and catalyst required to convert lipids to their alkyl esters (biodiesel). A design of experiments was conducted to understand the impact of process variables in the production of Fatty Acid Methyl Ester (FAME) from Chlorella vulgaris Microalgae. Three process variables (catalyst ratio, solvent ratio and reaction time) were studied, based on their process significance. The maximum FAME recovery of 77.6 ± 2.3 wt% was obtained at a reaction time of 75 min, using a catalyst:lipid (NaOH) molar ratio of 0.15:1 and a methanol:lipid molar ratio of 600:1. Additional experiments were performed at the optimum methanol ratio (600:1) to compare results obtained using an alkaline catalyst with an acid catalyst. In terms of time, the alkaline catalyst (sodium hydroxide) outperformed the acid catalyst (sulphuric acid) obtaining higher conversions at lower reaction times. Nevertheless, using an acid catalyst ratio of 0.35:1 for longer reaction times resulted in higher conversions, up to 96.8 ± 6.3 wt%, and may have facilitated the breakage of Microalgae Cell walls. In conclusion, the alkaline in situ transesterification of algal biomass can achieve high conversion in less time than an acid catalyst, using a lower ratio of catalyst. The final selection of the type of catalyst will depend on the characteristics (batch vs continuous) and cost of the in situ transesterification including catalyst and methanol costs, and the downstream processes required to obtain a saleable biodiesel.