In situ ethyl ester production from wet algal biomass under microwave-mediated supercritical ethanol conditions

• Published in: Bioresource technology 2013-07, Vol.139 (2013), p.308-315
• Main Authors: Patil, Prafulla D., Reddy, Harvind, Muppaneni, Tapaswy, Schaub, Tanner, Holguin, F. Omar, Cooke, Peter, Lammers, Peter, Nirmalakhandan, Nagamany, Li, Yin, Lu, Xiuyang, Deng, Shuguang
• Format: Article
• Language: English
• Subjects: 09 BIOMASS FUELS; Absorption - drug effects; Algae; Algal biomass; Biodiesel; Biofuel production; Biofuels - microbiology; Biological and medical sciences; Biomass; Biotechnology; Energy; Esterification - drug effects; Esters - metabolism; Ethanol; Ethanol - pharmacology; Ethyl alcohol; Ethyl esters; Fatty Acids - metabolism; Fundamental and applied biological sciences. Psychology; In situ transesterification; Industrial applications and implications. Economical aspects; Lipids - isolation & purification; Microalgae - drug effects; Microalgae - metabolism; Microalgae - ultrastructure; Microwave irradiation; Microwaves; Nannochloropsis salina; Nutrients; Oxidation-Reduction - drug effects; Supercritical ethanolysis; Thermodynamics; Time Factors; Transesterification
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.04.045

[Display omitted] •Direct conversion of wet algae to biodiesel under supercritical ethanol conditions.•Study the effects of algae to ethanol ratio and reaction time on algal biodiesel yield.•Controlled microwave power conditions with passive heating elements (SiC).•No expensive and extensive harvesting and drying steps for algal biodiesel production.•In situ transesterification using a green solvent and catalyst-free approach. An in situ transesterification approach was demonstrated for converting lipid-rich wet algae (Nannochloropsis salina) into fatty acid ethyl esters (FAEE) under microwave-mediated supercritical ethanol conditions, while preserving the nutrients and other valuable components in the algae. This single-step process can simultaneously and effectively extract the lipids from wet algae and transesterify them into crude biodiesel. Experimental runs were designed to optimize the process parameters and to evaluate their effects on algal biodiesel yield. The algal biomass characterization and algal biodiesel analysis were carried out by using various analytical instruments such as FTIR, SEM-EDS, TLC, GC–MS and transmission electron microscopy (TEM). The thermogravimetric analysis (TGA) under nitrogen and oxygen environments was also performed to examine the thermal and oxidative stability of ethyl esters produced from wet algae. This simple in situ transesterification process using a green solvent and catalyst-free approach can be a potentially efficient route for algal biodiesel production.