No abstract

Strain selection is one of the primary hurdles facing cost-effective microalgal biodiesel production. Indeed, the strain used affects both upstream and downstream biodiesel production processes. This study presents a screening procedure that considers the most significant criteria in microalgal biodiesel production including TAG production and wet extraction and recovery of TAGs. Fourteen freshwater and seawater strains were investigated. Large variation was observed between the strains in all the screening criteria. The overall screening procedure ultimately led to the identification of Parachlorella kessleri UTEX2229 and Nannochloropsis gaditana CCMP527 as the best freshwater and seawater strains, respectively. They featured the largest areal TAG productivity equal to 2.7×10(-3) and 2.3×10(-3)kgm(-2)d(-1), respectively. These two strains also displayed encouraging cell fragility in a high pressure bead milling process with 69% and 98% cell disruption at 1750bar making them remarkable strains for TAG extraction in wet environment.

Triacetin, an alternative biodiesel additive, was prepared by esterification of glycerol with acetic acid in the presence of chemically activated natural zeolite. The esterification was carried out in a small reaction flask under microwave irradiation. The catalyst was characterized for its morphology by SEM and its chemical composition by X-ray Diffraction (XRD). The Scanning Electron Microscopy (SEM) micrograph indicates improved surface area of the zeolite, while the XRD analysis shows an increase in Si/Al ratio from natural zeolite to 6.042 and its crystallinity value of 12.23%. The Fourier Transform Infra Red (FTIR) analysis obtained showed that microwave-heated samples have an esters group spectrum of triacetin at 1702 cm-1. The conversion value of glycerol was more than 95% at molar ratio of the reactants 1:9 and catalyst loading of 3%. The selectivities for monoacetin, diacetin and triacetin were 80.1%, 15.4%, and 4.5% at 60 minutes, and 43.0%, 48.6%, and 8.3% at 90 minutes. It shows that the conversion took place in consecutive steps and the use of microwave allows the reaction proceeding at milder condition. Copyright © 2019 BCREC Group. All rights reserved

Esterification of glycerol with acetic acid under microwave irradiation in the presence of activated natural zeolite was investigated. Natural zeolite was collected from Ujung Pancu (Aceh Besar) and chemically activated with hydrochloric acid. The reaction was carried out in a stirred glass flask reactor placed inside microwave oven. Experimental variables include microwave transmission time, molar ratio of glycerol to acetic acid, and catalyst loading. XRD profile of activated zeolite showed an increase of Si/Al ratio to 6.042 and the crystallinity decreased slightly by 12.23%, mainly due to dealumination during chemical treatment. Qualitative analysis by FTIR shows that the reaction product obtained by microwave heating contains ester group (triacetin) at wavelength 1706.669 cm -1 , while the quantitative analysis by acidi-alkalimetry titration indicates the highest glycerol conversion of 93.033% at the reaction condition of the molar ratio of 1:9, catalyst loading of 3%, and microwave transmission of 10 minutes. The present work suggests that microwave can be utilized as efficient heating technique in esterification of glycerol to triacetin.