Preparation of carboxymethyl chitosan-graft-β-cyclodextrin modified silica gel and preconcentration of cadmium

• A novel β-CD-grafted-CMCS modified silica gel sorbent was prepared.
• The sorbent combined the functionality of CMCS and advantages of β-CD.
• The sorbent could get a high preconcentration factor.
• The proposed method was applied to determination of Cd(II) in water samples.

Carboxymethyl chitosan (CMCS) grafted with β-cyclodextrin (CMCS-g-CD) modified silica gel as a new solid phase extraction (SPE) adsorbent for cadmium has been developed. The optimum batch experimental conditions (pH, amount of adsorbent and contact time) and column experimental conditions (concentration and volume of elution solution) were optimized, respectively. The kinetic models for Cd (II) were investigated and the results indicated that pseudo-second-order equation provided a better R2 (R2 > 0.999) and agreement between calculated Qe value (10.6 mg/g) and the experimental Qe (exp) value (11.3 mg/g). The developed method was successfully applied to the determination of Cd(II) in lake water and tap water with recoveries ranging from 96.0% to 102.0%.