Preparation method and application of alfalfa and ionic rare earth tailing composite catalyst

The invention discloses a preparation method and application of an alfalfa and ionic rare earth tailing composite catalyst, the composite catalyst and dye wastewater are mixed and stirred, persulfate is added for a degradation reaction (30-60 min), and degradation of dye in the wastewater can be completed. The composite catalyst used in the invention is prepared by mixing alfalfa powder and rare earth tailing powder and then carrying out co-pyrolysis. The composite catalyst is rich in nitrogen element and is beneficial to preparation of a nitrogen-doped biochar material; meanwhile, the rare earth tailings can provide a large number of active sites for the biochar, and the performance of activating the persulfate is improved. Experiments prove that the porous structure of the biochar catalyst is beneficial to adsorption of pollution reactants to the surface or pores of the catalyst, so that the degradation efficiency is further improved, and finally, efficient removal of dyes in water is realized. The composit