Abstract
We present mechanically strong macroporous, squeezable dextran cryogels as a column filling material for the removal and separation of binary organic dye and pesticide mixtures from aquatic medium. Dextran cryogels were prepared from aqueous solutions of dextran of various molecular weights (MWs) in the presence of 20 to 50 mol% divinyl sulfone (DVS) as a cross-linker at -18 degrees C. The cryogels have interconnected irregular pores of 100 mu m in sizes, and exhibit 69-84% reversible squeezability without damaging the 3D dextran network. Their total open pore volumes (6.3-10 mL g(-1)), weight swelling ratios in water (1380%-2200%), and mechanical parameters could easily be adjusted by both DVS mol% and MW of dextran. Dextran cryogel with the highest modulus (3.8 +/- 0.5 MPa), compressive stress (8 +/- 2 MPa) and plateau stress (0.46 +/- 0.04 MPa) was obtained at 50 mol% DVS using dextran with a MW of 15 to 25 kg center dot mol(-1). Dextran cryogels are hydrolysable at pH = 1 and 9 but stable at 7.4 independent on both the degree of cross-linking and MW of dextran. At below 50 mol% DVS, they are blood compatible and possess slight thrombogenic effect with blood clotting index value of 98% +/- 5%. They are also capable to separate binary dye and pesticide mixtures from aqueous solutions via ionic interactions.
