Process for preparing high-purity nano silicon dioxide from rice husk

Abstract

The method for preparing nano silicon dioxide by utilizing rice husk includes the following steps: firstly, preparing inorganic acid treatment agent whose concentration is 1-20 wt%, according to the weight ratio of 2-50:1 adding rice husk, boiling for 0.5-3 hr., washing with water, drying, combusting rice husk for 15-180 min, at 600-900 deg.C, pulverizing combusted product to obtain the invented nano silicon dioxide whose grain size is 30-80 nm and purity is 98-99.9%. The used treatment agent is HCl or H2SO4, etc. The combustion heat or the rice husk can be recovered, and can be used as heat source for drying treated rice husk and also can be used as heat source for other application including heating and bathing pool.

Description

technical field

[0001] The invention relates to a method for preparing nano silicon dioxide, in particular to a method for preparing nano silicon dioxide from agricultural by-product rice husks. Background technique

[0002] my country produces about 200 million tons of rice per year, which is converted into about 40 million tons of rice husks, accounting for more than 30% of the world's total output, ranking first in the world. According to theoretical calculations, my country can extract about 800 tons of rice from rice husks every year. 10,000 tons of high-purity SiO 2 . It is a pity that rice husk resources are not fully utilized at present and are wasted as agricultural waste. Chinese patent ZL 86107192 is to use rice husk as raw material, under the condition of no external energy, slowly heat up in the roasting furnace, roast at low temperature, so that the organic matter in the rice husk is fully decomposed and gasified, so as to achieve whitening and combustion to p...