Preparation method of magnetic cellulose nanocrystal

The invention discloses a preparation method of a magnetic cellulose nanocrystal. The method comprises the steps: adding cellulose raw materials into an acid solution, stirring at the temperature of 30-105 DEG C for 0.5-24h to react, and washing to obtain a cellulose nanocrystal; adding the cellulose nanocrystal into a 0.00005-1mol/L ferric salt solution, stirring for 0.1-3h, adding a chitosan solution, and stirring to obtain a cellulose nanocrystal and metal ion complex mixed solution; adding a sodium tripolyphosphate solution, stirring for 1-60min, adding an alkaline solution to adjust the pH value to 8-13, and reacting at the temperature of 20-90 DEG C for 0.1-3h; and after the reaction is ended, washing by using deionized water, and drying to obtain a magnetic cellulose material. Chitosan is added in the step of mixing the cellulose nanocrystal and the ferric salt solution, so that ferric ions are complexed with the chitosan, and furthermore, ferroferric oxide is more uniformly and tightly distributed on the surface of the cellulose nanocrystal material.