Facile preparation of chitosan modified magnetic kaolin by one-pot coprecipitation method for efficient removal of methyl orange

Abstract

Chitosan modified magnetic kaolin (CS/kaolin/Fe₃O₄) composite was prepared by a facile one-pot coprecipitation method and used for the removal of methyl orange (MO) from aqueous medium. Under alkaline condition, Fe₃O₄ nanoparticles were deposited on the kaolin layer by in-situ growth method and chitosan was deposited on the kaolin layer by pH-precipitation method. With the modification of CS, adsorption sites for anionic species were introduced onto the adsorbent. The prepared CS/kaolin/Fe₃O₄ could remove more than 94 % of MO and showed a high saturated adsorption capacity of 349.7 mg/g. The adsorption process was controlled by film diffusion and well described by Langmuir model. The thermodynamic studies indicated that the adsorption process was exothermic in nature. Furthermore, the adsorbent exhibited satisfactory recycle ability. The results suggested that the modification with CS broadened the application scope of kaolin in anionic species removal and the CS/kaolin/Fe₃O₄ composite could be a promising adsorbent for wastewater treatment.

Keywords: Adsorption; Chitosan; Magnetic kaolin; Methyl orange; One-pot coprecipitation.