Adsorption of copper by magnetic graphene oxide-supported beta-cyclodextrin: Effects of pH, ionic strength, background electrolytes, and citric acid

Elucidating the influence mechanism of surrounding environmental conditions on the adsorption process is essential in application of adsorption method for heavy metal removal from wastewater. In the present work, the magnetic graphene oxide-supported p-cyclodextrin (MGO/beta-CD) was synthesized and characterized by FESEM, TEM, TG-DSC, FT-IR, and zeta potential. The effects of pH, ionic strength, background electrolytes, and citric acid on the adsorption behavior of Cu(II) by MGO/beta-CD were investigated. The results showed that Cu(II) adsorption was strongly dependent on solution pH and could be affected by ionic strength, background electrolytes and citric acid. The Cu(II) adsorption was increased as the NaNO3 concentration increased from 0 to 0.1 M at pH<8. The presence of LiNO3, NaNO3, KNO3, NaCl, and NaClO4 enhanced the Cu(II) removal slightly. The Cu(II) adsorption was also improved by citric acid. Adsorption kinetics of Cu(II) was found to follow pseudo-second-order rate equation, and the adsorption rate was controlled by film diffusion. The adsorption data showed good correlation with the Freundlich and Temkin isotherm models. The results of this work are of great significance for the application of MGO/beta-CD as a promising adsorbent material for Cu(II) removal from aqueous solution. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.