Preparation of Dextran Cryogels and Some of Their Applications

Abstract

In this study, dextran (DEX) cryogels were prepared using 50% divinyl sulfone (DVS) crosslinker based on the repeating unit of DEX, under cryogenic conditions via cryogellation technique. It was shown that DEX cryogels can be used as column fillers to remove toxic substances such as organic dye, methylene blue (MB), pesticide, and paraquat (PQ) which are harmful to the environment and human health. The maximum absorption capacity of 15 mg DEX cryogels was determined as 10.69±0.14 mg/g using 5 mL of 100 ppm MB dye in about seven minutes, and as 2.87±0.33 mg/g from 5 mL of 40 ppm PQ pesticide in about ten minutes. The reusability of DEX cryogel for MB was also examined. In the consecutive use of DEX cryogel weighing ~30 mg, initially cryogel absorbed 6.43±0.15 mg MB/g cryogel from 20 ppm 30 mL MB dye, but this value decreased to 4.71±0.48 mg MB/g cryogel after the fifth use. The same cryogel released the same amount of MB dye after the first use of 3.78±0.33 mg MB/g cryogel, but after the fifth use the release amount decreased to 0.92±0.38 mg MB/g cryogel upon treatment with 1 M 30 mL HCl solution. The adsorption kinetics of DEX cryogel for MB were also examined and the Langmuir isotherm model with a correlation coefficient of 0.9983 and the KL value of 0.36, representing the best fit amongst the other well-known models such as the Freundlich isotherm, Temkin, Elovich and Dubinin-Radushkevich.