Modification method of coconut shell activated carbon

The invention provides a modification method of coconut shell activated carbon. The coconut shell activated carbon of 20-40 meshes is placed in a first reactor, then placed into a muffle furnace to be heated and oxidized at the temperature of 350-450 DEG C and cooled to the room temperature, a decomposition solution is added, and decomposition is performed at the temperature of 150-250 DEG C; treated activated carbon is filtered, separated and washed with deionized water until the pH value of a washing liquid ranges from 6 to 7; obtained activated carbon is added to a second reactor containing an alkali aqueous solution, the mixture is left to stand after being mixed, and then the alkali aqueous solution is filtered out; obtained activated carbon is added to a third reactor, placed into the muffle furnace to be activated at the temperature of 350-450 DEG C and then cooled to the room temperature, and modified coconut shell activated carbon is obtained. The coconut shell activated carbon obtained with the meth