RETRACTED: Graphene supported magnetically separable solid acid catalyst for the single step conversion of waste cooking oil to biodiesel

Abstract

Abstract Conversion of vegetable oils to biodiesel typically involves the use of highly corrosive acids or bases as catalysts. Solid catalysts can be used to avoid the use of corrosive mineral acids/bases and they have the possibility of reuse. Development of a highly active solid acid based on graphene oxide that can be recovered using magnetic seperation and reactivated by simple washing is reported here. High catalytic activity of the iron oxide supported on sulphonated graphene oxide (GO-Fe 2 O 3 SO 3 H) was established for the esterification of oleic acid as well as single step biodiesel production from waste cooking oil (WCO) using ethanol. Catalytic activity of GO-Fe 2 O 3 SO 3 H was higher than GO, GO-SO 3 H as well as GO-Fe 2 O 3 . Thorough characterization of the prepared catalysts was done using a number of spectroscopic, thermal and microscopic techniques. Complete conversion of oleic acid to its ethyl ester could be done in 4 h, at 100 °C using 5 (% by wt.) of the catalyst. Moreover, single step conversion of WCO to biodiesel could be achieved at 90 °C in 6 h using 5 wt % of the catalyst. The catalyst was reclaimed by magnetic separation and reused upto 7 cycles without any significant loss of activity.