Preparation method of mizue brocade straw activated charcoal

The invention provides a method for preparing loosestrife straw active carbon, comprising the steps that: 1. the loosestrife straw is dried and crumbled into fractions so as to be able to get through a 70 to 100 mesh sieve; 2. the loosestrife straw is steeped for 3 to 4 hours in phosphoric acid with 50 percent to 70 percent density at a dipping ratio of 2.5:1; 3. the loosestrife straw is put into an activating oven for carbonization and activation with the activation temperature of 450 DEG C to 500 DEG C for 1.5 to 2.5 hours, or the carbonization and activation are carried out in a microwave oven with the protection of nitrogen, the power of the microwave is 1000W and the microwave radiation time is 7 to 8 minutes; 4. then washing with water is carried out until getting a neutral status; finally, drying under 105 DEG C is carried out so as to obtain the loosestrife straw active carbon. The invention takes the loosestrife with a wide source as the raw material, thereby being easy to be operated and environment protective with low cost, and compared with active carbon prepared with other raw materials, the invention is characterized by a plurality of pore canals, good absorbability performance, larger surface area and more pore volume.