• dyes;
  • methylene blue;
  • adsorption isotherm;
  • kinetic model;
  • volcanic ashes;
  • nanomaterials


Volcanic ashes (VAs) and Ti-modified volcanic ashes (TVA) were investigated as inexpensive adsorbents to remove methylene blue (MB) from aqueous solutions. TVA displayed higher and faster MB adsorption than VA. Adsorption studies were carried out in a batch system at room temperature. In this work, several variables were studied: contact time, pH, initial MB concentration, and adsorbent dosage. The equilibrium data of MB adsorption were analyzed according to the Langmuir and Freundlich adsorption isotherm models. Optimum adsorption performance for TVAs particles, prepared using a hydrothermal method, was obtained at pH = 10 and 3 g/l adsorbent dose. MB adsorption isotherm data can be described satisfactorily by the Langmuir equation, whereas adsorption kinetic data fit a pseudo second-order kinetics model. © 2010 American Institute of Chemical Engineers AIChE J, 2011