RESUMO
The separation of Jatropha curcas oil from azeotropes of ethyl alcohol-n-hexane and isopropyl alcohol-n-hexane using ceramic membranes with different cutoffs (5, 10 and 20â kDa) is presented. The mass ratios of oil:azeotropes (O:S) studied were 1:3 for feeding pressures of 0.1, 0.2 and 0.3â MPa, and 1:1 for the feeding pressure of 0.1â MPa. Isopropyl alcohol was the best solvent for the membranes conditioning to permeate n-hexane (240â kg/m2â h). In the separation of J. curcas oil and azeotropes of solvents, both membranes showed oil retention and total flux decreases with time. Overall, the lowest decrease in the retentions was reached in the 5â kDa membrane, while the lowest decrease in the total flux was reached in the 20â kDa. In the separation of oil and ethyl alcohol-n-hexane azeotrope, the best retention at 60â min of the process was equal to 17.3â wt% in the 20â kDa membrane at 0.3â MPa and O:S ratio equalled to 1:3. In this condition, the total permeate flux was 17.5â kg/m2â h. Different retentions and permeabilities are provided when changing the O:S ratio, the feeding pressure and the molecular weight cutoff of membranes.
Assuntos
Cerâmica/química , Fracionamento Químico/métodos , Jatropha/química , Óleos de Plantas/isolamento & purificação , Solventes/química , 2-Propanol/química , Hexanos/química , Membranas Artificiais , Óleos de Plantas/químicaRESUMO
This work investigates the use of ceramic membranes with different molecular weight cut-offs (MWCOs: 5, 10 and 20â kDa) to desolventize azeotropic solvent mixtures (ethanol/n-hexane and isopropyl alcohol/n-hexane) from soybean oil/azeotrope micelles. Results show that a decrease in the MWCO of a membrane and an increase in the solvent mass ratio in the mixture resulted in a significant reduction in the permeate flux. The 20â kDa membrane presented the highest permeate flux, 80 and 60â kg/m2h for the soybean oil/n-hexane/isopropyl alcohol and soybean oil/n-hexane/ethanol azeotropes, respectively, for an oil to solvent ratio of 1:3 (w/w). The highest oil retention was found using the n-hexane/isopropyl alcohol azeotrope, around 25% in the membrane with the lowest MWCO, that is, 5â kDa. It is shown that the azeotropic mixtures provided intermediate characteristics compared to the original pure solvent behavior.