Hydrosterification/transesterification of waste frying oils in supercritical ethanol for biodiesel production.
Biodiesel, waste frying oils, supercritical ethanol, hydrosterification, transesterification, continuous flow reactor, experimental design.
The use of frying oils presents important characteristics for any proposal that seeks economic viability and is
environmentally friendly to the environment for the production of biodiesel. Economically, the residual oils are
cheap because they are raw materials of low quality and inexpensive compared to the oils commercialized in
Brazil today. Regarding the environmental aspect, studies on the environmental impact of incorrect disposal of
discarded oils in the water of rivers or surface aquifers show that one liter of discarded oil can pollute about
500,000 liters of water. Another very serious problem of incorrect disposal of waste oils is the inlays in pipelines
and pipelines of sewage networks in large urban centers. The accumulation of these wastes produces the formation
of a biomass (solid waste and microorganisms) that causes restrictions and difficulties in the effluent flows to the
treatment stations and produce clogging and generation of odors exhaled by the decomposition of this material.
These problems cause great economic impacts in the treatment and recovery of these water sources, cleaning,
replacement and clearing of these public sanitation equipment. In view of these findings, it was proposed the
development of a reactive route that could use cheap and low quality raw materials such as residual oils, that
would be economically feasible and that would help in reducing the environmental impacts produced by the
incorrect disposal of these oils. We performed reactions of frying oils with constant pressure of 100 bar, oil /
ethanol molar ratios of 1/10 and 1/30 and mass percentages of water of 10%, 20% and 30%, temperatures of
250 ° C, 290 ° C and 310 ° C and residence times of 15 min, 30 min and 45 min in continuous flow tubular
reactor. The results showed that the experiments with higher temperatures (290 ° C and 310 ° C) and residence
time (45 min) presented yields of 71%, 66%, 59% and yields of 31%, 29% and 27% for temperature of 290° C
and residence time of 30 minutes.