Adjust pH value. Iron removal is to use hydrogen peroxide to oxidize ferrous ions into ferric ions, and then adjust the pH value to completely precipitate the iron ions. Therefore, the purpose of adding H2O2 during the iron removal process is to oxidize Fe2 into Fe3 to facilitate the formation of precipitation and remove it. Adjust the pH of the solution and add And the reaction of substances and acids cannot introduce new impurities. A.ZnOB.ZnCO3C.Zn(OH)2 can react with acids without introducing new impurities.