A method for removal of metal ions from rice hull. The method includes: 1) providing a water storage reactor, and disposing a gas dispersion device at the bottom of the water storage reactor 2) bagging rice hull, placing it in the water storage reactor, and pressing down on the bagged rice hull to be lower than a water surface in the water storage reactor 3) spraying industrial flue gas into the water storage reactor controlling the amount of the industrial flue gas such that the amount of carbon dioxide dissolved in per 100 g of water is about 1 g, whereby generating a carbonic acid solution 4) allowing the carbonic acid solution to react with metal ions in the rice hull to yield a precipitate and 5) washing the rice hull collected in step 4), washing again with desalinated water, and then squeezing the rice hull.
