EDTA modified β-cyclodextrin/chitosan for rapid removal of Pb(II) and acid red from aqueous solution

EDTA modified β-cyclodextrin/chitosan (CDCS-EDTA) was fabricated successfully by a two-step method and applied to remove Pb(II) and anionic dye acid red 73 (AR). CDCS-EDTA was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta potential analysis. The effects of experimental parameters including adsorbent dose, contact time and pH value on the adsorption efficiency of CDCS-EDTA for the pollutants were investigated. The maximum adsorption capacities were 114.8 mg g^-1 for Pb(II) and 754.6 mg g^-1 for AR under the optimal conditions. 93.4% of Pb(II) and 92.1% of AR could be adsorbed within 5 min, and the adsorptions reached equilibrium rapidly within 20 min and 10 min for Pb(II) and AR, respectively. A possible adsorption mechanism had been proposed that chelation of EDTA and electrostatic attraction of hydroxyl and amino groups dominated the adsorption of Pb(II), while the adsorption of AR mainly by the formation of inclusion complex with cyclodextrin cavities and electrostatic attraction with functional groups. For these two pollutants, the adsorption kinetic and isotherm data fitted well with the pseudo-second-order model and the Langmuir model, respectively. Thermodynamic studies implied that the adsorption process of Pb(II) and AR were spontaneous. Furthermore, the excellent regeneration performance indicated that CDCS-EDTA has a promising application in water treatment.