Methods and nanocomposites for the adsorptive removal of aromatic hydrocarbons such as benzene, toluene, ethyl benzene and xylene from contaminated water sources and systems are provided. The nanocomposites contain carbon nanotubes and metal oxide nanoparticles such as Al2O3, Fe2O3 and ZnO impregnated on a surface and/or in pore spaces of the carbon nanotubes. Methods of preparing and characterizing the nanocomposite adsorbents are also provided.