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Author: search.filters.author.Guldhe, AbhishekHas files: No

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    Synthesis of biodiesel from Scenedesmus sp. by microwave and ultrasound assisted in situ transesterification using tungstated zirconia as a solid acid catalyst
    (Elsevier, 2014-05-20) Guldhe, Abhishek; Singh, Bhaskar; Rawat, Ismail; Bux, Faizal
    Oleaginous Scenedesmus sp. was cultivated phototrophically in an open pond for biofuels production. The culture was harvested and subsequently dewatered and dried. The chemical properties of the Scenedesmus sp. lipids were determined as per standard ASTM methods. Biodiesel was synthesized by in situ transesterification from dried biomass using microwave and sonication techniques with tungstated zirconia (WO3/ZrO2) as a solid acid catalyst. In situ transesterification allowed minimizing the requirement of solvents by merging the two steps (i.e. extraction of lipid and conversion to biodiesel) to a single step. The use of a solid catalyst effectively reduces the purification cost of biodiesel due to ease of separation and potential for reuse. The conversion of Scenedesmus sp. lipids to biodiesel was determined by GC. Box–Behnken design was used for optimization of the variables to optimize the biodiesel yield and conversion. The efficiency of the two processes was compared.
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    The optimization of biomass and lipid yields of Chlorella sorokiniana when using wastewater supplemented with different nitrogen sources.
    (Pubmed, 2014-09) Ramanna, Luveshan; Guldhe, Abhishek; Rawat, Ismail; Bux, Faizal
    The potential of nitrogen sources supplementing domestic wastewater for the cultivation of microalgae was assessed. Urea, potassium nitrate, sodium nitrate and ammonium nitrate were evaluated for their effect on cultivation and lipid production of Chlorella sorokiniana. Urea showed the highest biomass yield of 0.220 g L−1 and was selected for further experimentation. Urea concentrations (0–10 g L−1) were assessed for their effect on growth and microalgal physiology using pulse amplitude modulated fluorometry. A concentration of 1.5 g L−1 urea produced 0.218 g L−1 biomass and 61.52% lipid by relative fluorescence. Physiological stress was evident by the decrease in relative Electron Transport Rate from 10.45 to 6.77 and quantum efficiency of photosystem II charge separation from 0.665 to 0.131. Gas chromatography analysis revealed that C16:0, C18:0, C18:1, C18:2 and C18:3 were the major fatty acids produced by C. sorokiniana. Urea proved to be an effective nitrogen supplement for cultivation of C. sorokiniana in wastewater.