The calcium alginate gel beads（CAGB） are modified via graft copolymerization with acrylonitrile（AN）. It is found that the grafting yield achieved 799% when 5.0 g CAGB（in diameter of 3.2 mm） is mixed with 0.033 9 mol/L K2S2O8 for 35 min at 51 ℃ and copolymerized with 2.85 mol/L AN for 4 h. The structure of CAGB-g-PAN is verified with FTIR. The compactness of CAGB and modified CAGB is investigated with fluorometry. It is found that the compactness of the gel beads is increased with the grafting yield. Modified CAGBs keep their integrity in the electrolyte solutions that are capable of decomposition of CAGB, indicating the stability of CAGB is greatly enhanced.
