Study On Solubility Of P-Hydroxybenzaldehyde,m-Hydroxybenzaldehyde And Their Mixture In Supercritical Carbon Dioxide

As a new technology of chemical engineering, supercritical fluid technology has been intensively researched for industrialization, such as cosmetics, agriculture and food, medicine, pharmaceuticals, textiles, coatings and semiconductors. In order to improve the wide application of supercritical fluid technology, it is necessary to obtain the equilibrium solubility of some solid solutes in supercritical carbon dioxide (SCCO2), and there are fewer researches about experiment and theories of SCFs. The solubility of p-hydroxybenzaldehyde (p-HBA) and m-hydroxybenzaldehyde (m-HBA), and their mixtures in SCCO2was measured and studied through experiment and modeling which were discussed in this work.In order to measure the solubility of p-HBA, m-HBA and their isomeric mixture in birnary, ternary, and quadruple system by a dynamic method, the operating conditions were determined at temperatures of (308,318, and328) K and pressures (11.0,13.0,15.0,18.0and21.0) MPa. The cosolvents were chosen as follows:ethanol, ethylene glycol, ethyl acetate, and acetone. The mole fraction of each cosolvent is determined for0.04. The experiment obtains60groups equilibrium solubility of single p-UBA and single m-HBA, and60groups data of isomeric mixture. This work makes the solubility data to be more exuberant and makes the technology to being industrialized as well.In order to understand the comparison among lots of solubility data, some definitions are established as following:the enhancement coefficient of cosolvent (e), solubility relative enhancement coefficient (SE), separation factor (ju) of isomeric mixture in SCCO2system and separation efficiency (HE) in ternary system.The solubility of each isomer of hydroxybenzaldehyde in SCCO2was calculated by5semiexperical models, while the solubility of each isomer of hydroxybenzaldehyde in (SCCO2+cosolvent) system was calculated by4models. The MST model verified that the solubility data of each isomer of hydroxybenzaldehyde had a high self-consistency.Analyzed the correlation results of the previous models, and based on the Chemical Associated Theory, a new model called Sovova-T, is established to correlate the mixture solubility which consists of two solutes in ternary system. There are18couples of mixture which include636groups of solubility data are chosen to verify the accurate of the new model. The values of AARD of the new model are lower than other four parameters models (modified Chrastil, modified MST, and modified Sovova models), which indicate the new model has a higher applicability for ternary system than the others.