One of the problems with activated carbon is the disposal of adsorbed contaminants along with the adsorbent. Another concern is that its pores are often blocked during adsorption. By contrast, carbon nanotubes' (CNTs) open structure offers easy, undisrupted access to reactive sites located on nanotubes' outer surface. That's why researchers see CNTs as an attractive potential substitute for activated carbon. Researchers now have demonstrated that individual CNTs can be integrated into micrometer-sized colloidal particles without using a heavy or bulky particulate support.