Carbon nanotubes (CNTs) have been widely used materials in industry as well as in scientific research. These materials have special structures and functions. As a consequence of their pervasive use, their potential adverse effect on the environment is of concern to environmental scientist. For instance, CNTs may enhance the toxicity of polycyclic aromatic hydrocarbons (PAHs) after release to the environment due to the fact that they are superior sorbents. In environmental water system, natural colloids widely exist. The interaction between natural colloids and CNTs may change the adsorption of PAHs on CNTs. This research investigates adsorption capacity between two different CNTs and PAHs namely, napththalene, phenanthrene and pyrene in water and in the presence of colloids. Adsorption capacity of two multi-walled CNTs was examined in the presence of pure water, 0.5 ppm through 20 ppm of selected PAHs. This is then followed by a study of the interaction between these two CNTs and natural colloids filtered from lake water. In order to get colloids, water is collected from lake. Then prefiltration with 0.45 pore size um membrane and ultrafiltration with 10,000 molecular weight cutoff membrane are employed. The adsorption of PAHs to CNTs equilibrated with colloids will also be determined. All our samples are extract from water phase to organic phase by using Solid Phase Extraction(SPE) and Liquid-Liquid Extraction(LLE) methods, followed by GC-MS as a quantification tool. Adsorption isotherms are then fit over the concentration ranges and PAHs analyzed. Results obtained from this planned study will enable the evaluation of the potential environmental impact of CNTs as sorbent materials. Also the nature of the interaction of the colloids with CNTs will be useful in determining their environmental applications. The present work is ongoing. We hope to generate enough data in a few months.