Preparation method of modified activated carbon adsorbent for flue gas demercuration and application of modified activated carbon adsorbent

The invention provides a preparation method of a modified activated carbon adsorbent for flue gas demercuration. Activated carbon granules are washed clean with deionized water and dried, and the largest solution absorbing volume of tested activated carbon is tested; the concentration of a to-be-prepared carboxylic acid solution with more than one carboxyl is calculated according to the impregnant quantity of carboxylic acid with more than one carboxyl; the dry activated carbon is impregnated in the solution and dried after being taken out, and the modified activated carbon adsorbent with more than one carboxyl and for coal-fired flue gas demercuration is prepared. The preparation method has the advantages that the mercury adsorption capacity is large, the preparation method is simple and quick, raw materials used for the preparation method are flexible, various and low in cost mostly, the preparation method is environment-friendly and has wide application prospect.