Preparation of Urea-Imprinted Cross-Linked Chitosan and Its Adsorption Behavior

A surface molecular imprinting technique was used to prepare a novel molecularly imprinted polymer using urea as the template molecule, chitosan as the functional matrix, epichlorohydrin as the cross-linker, and formaldehyde as the amino-protecting agent. Infrared analysis of the polymer confirmed that urea was successfully imprinted on cross-linked chitosan. On the basis of a single-factor test, Box-Behnken central composite experimental design and response surface methodology were used to optimize the preparation conditions. The optimum preparation conditions included 0.05mL of acetic acid, 0.79g of urea, a pre-polymerization time of 2.41h, 1.63mL of epichlorohydrin, and 0.6g of chitosan. The predicted maximum adsorption capacity of urea (9.53mg/g) was consistent with the experimental value (9.61 +/- 0.16mg/g), which confirmed the accuracy of the response surface method to optimize the preparation conditions of molecularly imprinted polymer. The recycling rate of the molecularly imprinted polymers was up to 84.6%. The molecularly imprinted polymer was used to adsorb urea from a serum sample. The adsorption efficiency had a maximum value of 54.51%.