Method for removing phosphorus in water body by using adsorption of nano-lanthanum oxide modified alkali lignin

The invention discloses a method for removing phosphorus in a water body by using adsorption of nano-lanthanum oxide modified alkali lignin. The method comprises the following steps: dissolving the alkali lignin into water, adding polyethylenimine and a formaldehyde solution and carrying out a Mannich reaction in an alkaline environment; carrying out a hydrothermal reaction of a product by adopting lanthanum chloride as a lanthanum source in an ethanol aqueous solution to prepare the nano-lanthanum oxide modified alkali lignin; adding the nano-lanthanum oxide modified alkali lignin into a phosphorous-containing water body and removing the phosphorus in the water body by adsorbing. The surface of the lanthanum oxide modified alkali lignin prepared according to the hydrothermal method has highly-dispersed active lanthanum adsorption sites, and shows excellent removal effect and higher cyclic utilization rate for the phosphorus; in addition, the adsorption time is short and the treatmentefficiency is high; the a