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

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.