Antirust carbon steel pickling agent and preparation method thereof

The invention relates to the technical field of carbonic acid pickling rust prevention, in particular to a rust-proof carbon steel pickling agent and a preparation method thereof, and the rust-proof carbon steel pickling agent comprises the following raw materials by weight: 0.4-1.2% of a complexing agent, 3-4.5% of hydrochloric acid, 0.6-1.6% of molybdate, 0.5-1.5% of DL-methionine, 3-5% of a film-forming agent, 2-4% of a corrosion inhibitor, 0.3-0.7% of an anionic surfactant, and the balance of deionized water. The rust-proof carbon steel pickling agent meets the requirements of environmental protection, no phosphorus and no heavy metal, and is suitable for rust removal and scale removal of carbon steel, the carbon steel treated by the process can well keep bright natural color, is not over-corroded, is not greyed, does not generate a black film, is not rusted in a naked test of 7D or above in a natural environment, is suitable for rust removal, and is also suitable for rust removal and scale removal. And t