Adsorption behavior of methylene blue on halloysite nanotubes

The halloysite nanotubes (HNTs) were used as nano-adsorbents for the removal of the cationic dye, methylene blue (MB), from aqueous solutions. The dye adsorption experiments were carried out by using bath procedure. Experimental results have shown that the basic pH, increasing initial dye concentration and lower temperature favored the adsorption. The dye adsorption equilibrium was rapidly attained after 30 min of contact time. The factors controlling the adsorption process were also calculated and discussed. And a maximum adsorption capacity of 84.32 mg/g of methylene blue was achieved. It was noted that the dye adsorbed halloysite nanotubes had poor stability in aqueous suspension and deposited completely within 30 min while the original aqueous suspension of halloysite nanotubes remained stable for months. (C) 2007 Elsevier Inc. All rights reserved.