Method for preparing amorphous silicon dioxide from water hyacinth

The invention discloses a method for preparing amorphous silicon dioxide from water hyacinth. The method comprises the following steps: pretreating fresh water hyacinth; calcining at high temperatureto obtain ash, cooling to room temperature, and mixing with a hydrochloric acid solution; stirring at room temperature for 120-180 min; centrifuging to separate out a solid phase; washing the solid phase with distilled water to be neutral; mixing with a sodium hydroxide solution; placing the mixture in an oil bath for heating and stirring; filtering and then adding the hydrochloric acid solution into the filtrate to adjust the pH value to 5-7; aging at room temperature for 24-48 h to generate white flocculent precipitates; and filtering, washing and drying to obtain the amorphous silicon dioxide. The method provided by the invention solves problems that the water hyacinth is widespread and uncurbed and damages the balance of a domestic ecological system, opens up a new way for the production of silicon dioxide, ac