Highly efficient removal of polycyclic aromatic hydrocarbons from water using organophilic clays obtained from simultaneous ion exchange and grafting

Abstract

Abstract The present work analyses the polyaromatic hydrocarbons (PAHs) removal from water through batch adsorption processes, using two low-cost surfactant-grafted bentonites (Mt/TPODAC-1.5 and H5-Mt/TPODAC-1.5).These materials were prepared via a modification of montmorillonite (Mt) and acid-activated bentonite (H5-Mt) by intercalation and grafting of (3-trimethoxysilylpropyl) octadecyldimethylammonium chloride (TPODAC). Anthracene (ANT) was used as PAH model to assess the sorption capacity of each material. It was found that the selective modification of clay mineral has higher adsorption capacity for ANT compared with raw clay. Mt/TPODAC-1.5 and H5-Mt/TPODAC-1.5 removed 91 % and 85 % of ANT from water, respectively, while the raw bentonite (Mt) removed only 22 % under the same conditions. The adsorption isotherms were S-shaped and were fitted by the Frumkin-Fowler-Guggenheim (FFG) model, exhibiting an adsorption cooperative behaviour. The results indicate that hydrophobic and cation-π interactions ruled the ANT sorption on the modified clays. Simultaneous adsorption experiments with a mixture of 16 PAHs showed a high removal capacity of both modified clays. The promising results obtained in this work highlights the use of the TPODAC-grafted bentonite as potential sorbents to removal PAHs in a simple, economical, and environmentally friendly way.