Solubility of pyridine-2,6-dicarboxylic acid in supercritical carbon dioxide and its application for removal of lead and nickel in simulated matrices

Abstract

The solubility of pyridine-2,6-dicarboxylic acid in supercritical carbon dioxide was measured at 313–333 K and 10–20 MPa, using a flow-saturation technique. The influence of methanol on solubility behavior is investigated. The solubility in neat supercritical carbon dioxide ranged from 0.44 × 10−6 mol·moltot−1 to 3.4 × 10−6 mol·moltot−1, while its solubility in presence of methanol ranged from 0.17 × 10−5 mol·moltot−1 to 18.1 × 10−5 mol·moltot−1. The solubility data was modeled with Chrastil, Mendez-Teja, Garlapati equations and Peng-Robinson equation of state model. The solubility in the presence of methanol was correlated using modified Chrastil, modified Mendez-Teja and Thakur models. Among the models employed, Chrastil model (binary system) and modified Mendez-Teja model (ternary system) shown highest accordance with experimental data. Pyridine-2,6-dicarboxylic acid was employed as a chelating agent for development of a supercritical fluid extraction method for removal of Pb2+ and Ni2+ from simulated aqueous/soil matrices.