Method for removing formaldehyde from formaldehyde-containing gas

The invention discloses a method for removing formaldehyde from a formaldehyde-containing gas. The method is characterized in that the formaldehyde-containing gas is sequentially introduced to an absorption liquid A and an absorption liquid B so as to remove formaldehyde, wherein the absorption liquid A is an ammonium salt solution or ammonium hydroxide, the pH range of the absorption liquid A is 8-14, and the absorption liquid B is a sodium chloride solution. According to the method provided by the invention, the ammonium salt solution or ammonium hydroxide, which serves as the absorption liquid A, can react chemically with formaldehyde under an alkaline environment, the reaction is complete and high in efficiency, and the produced compound can be recycled and reused in the pharmaceuticals industry; besides, the absorption liquid A used in the method, such as ammonium hydroxide, ammonium chloride and ammonium bicarbonate are safe, low in cost and easy to purchase, the reaction condition is mild, the operation is simple and convenient, and the reaction can be realized at the temperature of 10-36 DEG C under usual atmospheric pressure.