Ho-mu Lin

Biodiesel production with continuous supercritical process: non-catalytic transesterification and esterification with or without carbon dioxide.

The non-catalytic transesterification of refined sunflower oil with supercritical methanol, in the presence of carbon dioxide, was conducted in a tubular reactor at temperatures from 553.2 to 593.2K and pressures up to 25.0 MPa. The FAME yield can be achieved up to about 0.70 at 593.2 K and 10.0 MPa in 23 min with methanol:oil of 25:1 in molar ratio. The effect of adding CO2 on the FAME yield is insignificant. The kinetic behavior of the non-catalytic esterification and transesterification of oleic acid or waste cooking oil (WCO) with supercritical methanol was also investigated. By using the supercritical process, the presence of free fatty acid (FFA) in WCO gives positive contribution to FAME production. The FAME yield of 0.90 from WCO can be achieved in 13 min at 573.2K. The kinetic data of supercritical transesterification and esterifaication were correlated well with a power-law model.

Solubilities of disperse dyes of blue 79, red 153, and yellow 119 in supercritical carbon dioxide

Abstract Extraction of disperse blue 79, red 153, and yellow 119 with supercritical carbon dioxide was investigated, respectively, at 393.2 K and 30 MPa over a wide range of contact times. The dissolution rates of these three dyestuffs were compared. Equilibrium solubilities were also measured over the temperature and pressure ranges of 353.2–393.2 K and 15–30 MPa. As evidenced from the experimental results, the solubilities increase dramatically with increasing pressure and are not as sensitive to temperature. The magnitudes of the solubilities are in the sequence of disperse blue 79>disperse yellow 119>disperse red 153 as pressures higher than 20 MPa. The equilibrium solubility data were correlated with the Chrastil equation. The association numbers of the Chrastil model are approximately 10, 8, and 7 for disperse blue 79/CO 2 , disperse red 153/CO 2 , and disperse yellow 119/CO 2 , respectively.

Cosolvent Effects on the Solubilities of Disperse Dyes of Blue 79, Red 153 and Yellow 119 in Supercritical Carbon Dioxide

In the presence of ethanol as a cosolvent, the equilibrium solubilities of the dyestuffs in supercritical carbon dioxide were measured at 393.15 K and pressures from 20 to 30 Mpa. The experimental results showed that the solubilities increased substantially by adding Mendez-Santiago-Teja correlated these solubility data to within experimental uncertainty.