| CPC C08B 37/0063 (2013.01) | 8 Claims |
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1. A method for separating and purifying fucoidan, comprising the following steps:
S1, subjecting a Undaria pinnatifida powder to extraction in hot water with a solid-to-liquid ratio of 1 g:20 mL, conducting filtration to obtain a filtrate, and concentrating the filtrate through rotary evaporation to a volume of 40% to 50% of an initial volume of the filtrate to obtain a concentrate;
S2, adding an aqueous calcium chloride solution with a mass fraction of 2% to the concentrate obtained in S1 in batches, such that a calcium alginate gel is produced until there are free calcium ions in the concentrate, that is, the aqueous calcium chloride solution is excessive; and
S3, adding chitosan-crosslinked graphene oxide/ferroferric oxide to a resulting material system obtained in S2 to obtain a mixed system, placing the mixed system at room temperature, and chelating excessive calcium ions obtained in S2 while adsorbing proteins by the chitosan-crosslinked graphene oxide/ferroferric oxide;
wherein in S3, the chitosan-crosslinked graphene oxide/ferroferric oxide is added in an amount of 4.0 mg/mL to 6.0 mg/mL relative to a volume of the resulting material system;
S4, conducting filtration to filter out a solid, and obtaining a liquid, wherein the liquid is an aqueous fucoidan solution; and concentrating the liquid to a volume of 40% to 50% of an initial volume of the liquid; and
S5, adding ethanol to a resulting concentrate obtained in S4 to precipitate the fucoidan, and then filtering and drying the fucoidan to obtain purified fucoidan;
wherein the method further comprises, before adding the chitosan-crosslinked graphene oxide/ferroferric oxide to the resulting material system obtained in S2, preparing the chitosan-crosslinked graphene oxide/ferroferric oxide by the following steps:
S31, dissolving chitosan in an acetic acid solution, adjusting a pH of a resulting solution to 5.5 to 6.0 using an NaOH solution, and stirring to obtain a chitosan solution;
S32, dispersing graphene oxide/ferroferric oxide in the chitosan solution, and conducting ultrasonic dispersion, such that the chitosan is self-assembled on the graphene oxide/ferroferric oxide, wherein a mass ratio of the graphene oxide/ferroferric oxide to the chitosan is in a range of 1:10 to 1:20;
S33, adding glutaraldehyde and conducting a crosslinking reaction; and
S34, subjecting a resulting reaction product to suction filtration to obtain a precipitate, and subjecting the precipitate to washing, lyophilizing, and crushing in sequence to obtain chitosan-crosslinked graphene oxide/ferroferric oxide particles; and
the method further comprises, before dispersing the graphene oxide/ferroferric oxide in the chitosan solution, preparing the graphene oxide/ferroferric oxide by the following steps:
S321, dissolving FeCl3·6H2O and FeCl2·4H2O at a molar ratio of 2:1 in deionized water, and stirring for full dissolution to obtain an aqueous solution of the FeCl3·6H2O and the FeCl2·4H2O;
S322, adding the aqueous solution of the FeCl3·6H2O and the FeCl2·4H2O to a graphene oxide solution under constant speed stirring, and further stirring to obtain a homogeneous mixed solution;
S323, adding aqueous ammonia dropwise to the homogeneous mixed solution obtained in S322 under stirring until a pH of the homogeneous mixed solution is adjusted to 8 to 9, and conducting crystallization to obtain the graphene oxide/ferroferric oxide; and
S324, separating the graphene oxide/ferroferric oxide by suction filtration, and washing and vacuum-drying a resulting separated graphene oxide/ferroferric oxide to obtain a graphene oxide/ferroferric oxide magnetic nanocomposite.
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