Removal of total petroleum hydrocarbon from water using attapulgite fiber silica aerogel composite

Abstract

Composite hydrophobic attapulgite fiber silica aerogels (AF-SAs) were prepared by modifying aerogels with AF. AF-SA composites with various fiber contents were prepared using a sol–gel method. The composite containing 0.30 g of added fiber was a typical nanoporous material; it had a specific surface area of 594.08 m2/g, a porosity of 75.00%, a pore volume of 2.15 cm3/g, and an average pore diameter of 84.74 nm. The kinetics of total petroleum hydrocarbon (TPH) adsorption onto AF-SAs was second order, and the isothermal adsorption of TPH conformed to the Langmuir adsorption model. The TPH adsorption capacity of an AF-SA, calculated using the Langmuir equation, was 5.00 g/g. Alkanes and aromatic hydrocarbons were both strongly adsorbed. The main adsorption mechanisms involved physical and chemical processes. The physical processes involved monolayer and multilayer adsorptions. Chemical adsorption occurred mainly after adsorption of TPH onto the AF-SA. The adsorption process was additionally assessed by monitoring the positions and areas of the Fourier-transform infrared absorptions of the main components (silicate, attapulgite, and functional groups of the surface-modification agent) of the composite materials.