Calculation method for determining phenanthrene solubility in supercritical CO2 employing Redlich-Kwong modified equation

摘要

Phenanthrene is a compound insoluble in water derived from petroleum which can be accumulated in organic matter. Phenanthrene is found in hydrocarbons mixtures. However, it requires efficient extraction methods. The relevance of calculating Phenanthrene solubility through modified state equation lies in the reduction of experimentation to predict the Phenanthrene concentration at different pressures during supercritical extraction. This research proposes a new method to determine the solubility of solids in supercritical fluids using a correlation based on Redlich-Kwong modified equation. In this method, the solubility of solids on equilibrium systems with solvents in a supercritical state was correlated with the Redlich-Kwong modified equation. Initially, the parameters a and b pertaining to modified equation were expressed by the Van der Waals rule; then two adjustable parameters (α and β) are defined and introduced into the equation for the calculation of solubility. α is related to the molecular interactions between the solute and solvent, and β with the molecular size. In order to find optimal values of adjustable parameters, the non-linear simplex method was employed. The proposed method is easy to use analytically and does not require the critical properties of the solid, which is important for thermolabile compounds. The average error ranged between 3% and 15%, acceptable for theoretical work.