Selective adsorption of thiocyanate anions using straw supported ion imprinted polymer prepared by surface imprinting technique combined with RAFT polymerization

Straw supported ion imprinted polymers for recognizing thiocyanate (SCN−) anions were prepared by surface imprinting technique combined with reversible addition-fragmentation chain transfer (RAFT) polymerization. The ability of the imprinted straw to adsorb SCN− ions was assessed using a batch adsorption technique. The sorption equilibrium could be reached within several minutes, and the maximum adsorption capacity was observed at pH 2.0. The imprinted straw exhibited better selectivity for SCN− ions than the non-imprinted straw. Relative selectivity coefficients for SCN−/CrO42−, SCN−/NO3− and SCN−/I− were 14.44, 13.97 and 14.19 respectively. The modified straw could be repeatedly used for 20 times without significant loss in the initial binding affinity. In addition, the imprinted straw was examined as a column packing material for solid phase extraction of SCN− ions. It was indicated that 1.0 and 0.5 mL/min were respectively the best load and elution flow rates for SCN− ions. The relative standard deviation of the seven replicate determinations of SCN− ions was 1.5%, and the detection limit of the proposed method was 0.42 ng/mL. The developed method was successfully applied to the determination of trace SCN− ions in various natural water samples with satisfactory results.