The invention discloses
sodium alginate and a preparation method and an application of the
sodium alginate. The preparation method comprises the following steps: (1) soaking water to soak and wash
brown algae, mixing and digesting with an alkaline agent, adding water to dilute, adding kieselguhr, filtering, and obtaining an
alginic acid monomer according to a
calcium coagulation acidification method; (2) degrading the
alginic acid monomer at the temperature of 30-50 DEG C; (3) taking
solid sodium carbonate as a neutralizer, mixing with the
alginic acid, stirring, carrying out a reaction to obtain a semi-finished product of
sodium alginate, then adding an
ethanol solution, stirring to disperse the semi-finished product of
sodium alginate into a
powder, pelleting,
drying and crushing to obtain the
sodium alginate. The
viscosity of the sodium alginate is 200-700 mpas, the
viscosity drop rate is lower than 5%, the Mw / Mn is less than 1.85, the
water content is less than 11%, the transparency is more than 30 cm, the
specific gravity of a
powder is 0.65-0.75 g / cm<3>, the
granularity is 120 meshes, and the distribution of the
powder granularity is narrow. The sodium alginate can be used ina
slow release formulation, and the slow release effect is stable.