Method for preparing smooth cord-grass active carbon for treating cadmium-containing waste water

The invention discloses a preparation method of Spartina alterniflora activated carbon, which can be used for treating cadmium wastewater. The method comprises the steps of oven-drying Spartina alterniflora stem and pulverizing; extracting the pulverized Spartina alterniflora powder with 0.1-10% of sulphuric acid solution for 1-10 hours; filtering the extracted solid-liquid mixture, and immersing the filter residue in phosphoric acid solution for 6-30 hours; oven-drying the immersed phosphoric acid-Spartina alterniflora mixture, activating by calcination at 400-700 DEG C under N2 as a protective gas for 0.5-10 hours to obtain activated carbon powder; and washing the obtained activated carbon powder and pulverizing. The inventive preparation method removes the interference of a large quantity of salts, and obtains the surface functional groups-enriched activated carbon product with yield of 42-48%. The obtained activated carbon can be used for treating cadmium wastewater with adsorption capacity in the range of 11-48.25mg/g, which is much higher than that of common commercial activated carbon. The obtained activated carbon takes full use of waste and creates great economic benefit and good social and environmental benefits.