Molecular dynamics simulation study: The reactivation of NaX zeolite contaminated by bi and tri aromatics using supercritical fluid extraction

摘要

In the present work, the supercritical fluid extraction (SFE) process was utilized to reactivate deactivated NaX zeolite with bi and tri aromatic contaminants (naphthalene and anthracene). In this direction, different parameters including extraction static time (30-120min), extraction pressure (80-350 bar), extraction temperature (323.15-373.15 K) and using two common and polar modifiers, methanol and dichloromethane, were investigated. The obtained results show that the optimum parameters were extraction pressure and temperature of 350 bar and 373.15, respectively as well as static time of 90 min to have the highest extraction value. However, modifiers did not display any significant influence on extraction efficiency. In addition, molecular dynamics simulations have been carried out to provide an atomic description of the supercritical carbon dioxide behavior with contaminants trapped inside NaX zeolite. The force field parameters were chosen carefully to examine self-diffusion coefficient of sorbates over a wide range of loading, temperature, and pressure. The simulated self-diffusivity was found to be in a reasonable agreement with the corresponding experimental data which evaluate the effectiveness of proposed calculation method and force field accuracy. All involved calculations were performed in time period 6 ns and repeated calculations have been done at least two times to confirm the results and applied average values, which made the results being reliable. (C) 2016 Elsevier B.V. All rights reserved.