Separation of Polycyclic Aromatic Compounds from Model Gasoline by Magnetic Alumina Sorbent Based on π-Complexation

Abstract

Magnetic alumina sorbent was used in the separation of aromatic compounds from gasoline by a π-complexation mechanism. Magnetic alumina sorbents can effectively adsorb polycyclic aromatics and polycyclic aromatic sulfur compounds from model gasoline, and the amounts adsorbed were up to 0.12 mmol·(g of sorbent)-1. The interactions between various aromatics and sorbents of different acidities were studied. The results showed that the amounts adsorbed are related to the capability of forming π-complexation interactions, and the magnetic alumina sorbent used was found to have the following order of adsorptive ability for aromatics: pyrene > naphthalene > DBT ≈ fluorene. Al3+ and its oxide are Lewis π-acids, and aromatic compounds are Lewis π-bases; thus, they can form π-complexes with each other. The π-complexation was verified by fluorescence spectrum. The quenching of the fluorescence of pyrene by Al3+ was due to partial π-electron transfer from pyrene to the cation according to Lewis theory and fluorescence quenching theory.