Efficient simultaneous removal of petroleum hydrocarbon pollutants by a hydrophobic silica aerogel-like material

Abstract

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) and monoaromatic hydrocarbons (MAHs), comprised in the petroleum, is slow and is associated with mutagenic, teratogenic and carcinogenic effects in humans. Aerogels are nanoporous, high surface area materials with easy recovery and high sorption capacities. In this work, the interaction between the aerogel-like material prepared with methyltrimethoxyslane (MTMS) and mix solutions containing MAHs (e.g., benzene, toluene and xylenes (BTXs)) and PAHs (e.g., pyrene, benzo(b)fluoranthene and benzo(a)pyrene) has been assessed. We found that the simultaneous sorption of all aromatic hydrocarbons occurs following a multilayer mechanism, highlighting the role of hydrophobic adsorbent-adsorbate and adsorbate-adsorbate interactions. We have also found that the removal efficiency is similar for all adsorbates and are equal to 16–18%, which leads to a total removal efficiency of around 100%. Desorption experiments show desorption efficiency of ca. 100% for PAHs; however, BTXs show higher interaction with the aerogel and lower desorption rates (below 50%). The silica aerogel-like adsorbent was characterized, before and after equilibrium with BTXs and PAHs solutions, by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The ability of this aerogel for removing all these pollutants from a real gasoline sample has also been tested.