Magnesium-aluminum hydrotalcite-loaded nano zero-valent iron composite material, method for preparing same and use thereof
It discloses a method for preparing a magnesium-aluminum hydrotalcite-loaded nano zero-valent iron material for specifically removing perfluorooctanoic acid in a water environment and an optimized process for removing perfluorooctanoic acid thereby, and relates to the technical field of removing persistent organic pollutants in water using adsorption method and oxidation-reduction method and, in particular, to a composite material prepared by loading a nano zero-valent iron on magnesium-aluminum hydrotalcite using liquid phase reduction method.
1. A method for preparing a magnesium-aluminum hydrotalcite-loaded nano zero-valent iron composite material, comprising:
(1) preparing a ferrous sulfate solution, bubbling nitrogen gas through the solution, adding magnesium-aluminum hydrotalcite, and stirring for mixing;
(2) dropwise adding a sodium borohydride solution to the mixed solution obtained in step (1) while stirring in a nitrogen atmosphere, and continuously stirring after the dropwise addition until a suspension is obtained; and
(3) centrifuging the suspension to obtain precipitate, washing the precipitate, and drying to obtain a magnesium-aluminum hydrotalcite-loaded nano zero-valent iron composite material.
2. The method according to claim 1 , wherein in step (1), the magnesium-aluminum hydrotalcite is ground and passed through a 50-mesh sieve.
3. The method according to claim 1 , wherein in step (2), the molar ratio of Fe 2+ in the ferrous sulfate solution to BH 4 − in the sodium borohydride solution is 1:2-1:4.
4. The method according to claim 1 , wherein in step (2), the sodium borohydride solution is dropwise added to the ferrous solution at 2-5 mL/min with stirring at 400-450 rpm in the nitrogen atmosphere.
5. The method according to claim 1 , wherein in step (2), the stirring at 400-450 rpm is continued for 10-30 min after the dropwise addition.
6. The method according to claim 1 , wherein in step (3), the nano zero-valent iron in the prepared composite material has a particle size of 100-500 nm.
7. The method according to claim 1 , wherein in step (3), the precipitate is washed with absolute ethanol and ultrapure water in sequence.
8. The method according to claim 1 , wherein in step (3), the centrifugation is performed at no less than 3000 rpm for no less than 10 min.