Algae extraction using microwaves

Accepted Manuscript
Optimization of microwave-assisted transesterification of dry algal biomass us‐ ing response surface methodology Prafulla D. Patil, Veera Gnaneswar Gude, Aravind Mannarswamy, Peter Cooke, Stuart Munson-McGee, Nagamany Nirmalakhandan, Peter Lammers, Shuguang Deng PII: DOI: Reference: To appear in: Received Date: Revised Date: Accepted Date: S0960-8524(10)01559-210.1016/j.biortech.2010.09.046 BITE 7555 Bioresource Technology 24 June 2010 4 September 2010 10 September 2010

Please cite this article as: Patil, P.D., Gude, V.G., Mannarswamy, A., Cooke, P., Munson-McGee, S., Nirmalakhandan, N., Lammers, P., Deng, S., Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology, Bioresource Technology (2010), doi:10.1016/j.biortech.2010.09.046

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Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology

Prafulla D. Patil a, Veera Gnaneswar Gude a, Aravind Mannarswamy a, Peter Cooke b, Stuart Munson-McGeea, Nagamany Nirmalakhandan c, Peter Lammers d, Shuguang Deng a*

Chemical Engineering Department a Electron Microscopy Lab b Civil and Environmental Engineering Department c New Mexico State University Las Cruces, NM 88003 U.S.A. Solix Biofuels, 430-B North College Ave, Fort Collins, CO 80524 d

*Corresponding author: Tel: +1-575-646-4346; Fax: +1-575-646-7706. E-mail address: sdeng@nmsu.eduTo be submitted to Bioresource Technology (online)

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Abstract The effect of microwave irradiation on the simultaneous extraction and transesterification (in-situ transesterifcation) of dry algal biomass to biodiesel was investigated. A high degree of oil/lipid extraction from dry algal biomass and an efficient conversion of theoils/lipids to biodiesel were demonstrated in a set of well-designed experimental runs. A response surface methodology (RSM) was used to analyze the influence of the process variables (dry algae to methanol (wt/vol) ratio, catalyst concentration, and reaction time) on the fatty acid methyl ester conversion. Based on the experimental results and RSM analysis, the optimal conditions for this process weredetermined as: dry algae to methanol (wt/vol) ratio of around 1:12, catalyst concentration about 2 wt%, and reaction time of 4 minutes. The algal biodiesel samples were analyzed with GC-MS and thin layer chromatography (TLC) methods. Transmission electron microscopy (TEM) images of the algal biomass samples before and after the extraction/transesterification reaction are also presented.

Keywords:Extractive transesterification; Dry algae; Biodiesel; Microwave-assisted extraction; Response surface methodology

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1. Introduction Microalgae, the third generation biofuel resource, have the potential to become a viable feedstock due to their high oil content and environmental-friendly nature (Gouveia and Oliveira, 2009). Themajor challenge, however, has been the high cost of recovering the oil from the microalgae prior to converting it into biodiesel. While there are many extraction methods such as solvent extraction, supercritical fluid extraction, ultrasonic extraction, and mechanical pressing; they require longer extraction times, large volumes of solvents, and are energy- and cost-intensive (Um and Kim, 2009;...