Use of chitosan derivatives as solid phase extractors for metal ions

This paper shows a comparative study between the two radiation grafted chitosan derivatives viz. cross-linked chitosan (CRC) and cross-linked chitosan after hydrolysis (CRCH). These chitosan derivatives were used as solid phase extractors for several radionuclides. The uptake of 137Cs, 85,89Sr, 152Eu, 241Am, 234Th and 233U by CRCH and CRC was studied using batch and column methods. The Kd, exchange capacity, breakthrough capacity for different metal ions with the functionalized polymers were determined. The uptake followed the following trend: 2+ UO2 >Th4+>Cs+>Eu3+>Am3+>Sr2+ for both sorbents. It was seen that CRCH had a greater uptake of metal ions compared to CRC but CRC was more selective of the two.

The results show that the CRC is selective for U as compared to other tetra-, tri-, bi- and monovalent cations. This selectivity may be due to the presence of nitrogen donors, which play a key role in binding with U. CRCH shows greater uptake Fig. 7. Breakthrough curves of U, Th and Eu by spectrophotometric method using Arsenazo III as the chromogenic agent (pH = 6.0).