Biodiesel production from wet microalgae by using graphene oxide as solid acid catalyst

- Graphene oxide (GO) catalyzed wet microalgae lipids into fatty acids methyl esters.
- GO contained 0.997 mmol of SO3H groups per gram and many OH groups.
- Hydrophilic GO surfaces adsorbed wet microalgal cells.
- GO achieved 95.1% lipids conversion efficiency.

In order to produce biodiesel from lipids in wet microalgae with graphene oxide (GO) as solid acid catalyst, the effects on lipids conversion efficiencies of catalyst dosage, transesterification temperature, reaction time, methanol dosage and chloroform dosage were investigated. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis revealed that GO contained 0.997 mmol SO3H groups per gram and high amounts of OH groups. Scanning electron microscopy showed that wet microalgae cells were adsorbed on hydrophilic GO surfaces covered with many OH groups. Lipids extracted by chloroform from microalgal cells were transformed into fatty acids methyl esters (FAMEs) through transesterification catalyzed by the acid centers (SO3H groups) in GO catalysts. The lipids conversion efficiency into FAMEs was 95.1% in microwave-assisted transesterification reactions of 5 wt.% GO catalyst at 90 °C for 40 min.

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