2. Precipitation method: By adding proper precipitant, zinc ions in the composite carbon source are combined with precipitant to form precipitation, so as to remove it. Commonly used precipitants include sodium hydroxide, calcium hydroxide and aluminum hydroxide. Precipitation method has the advantages of good removal effect and low cost.
3. Ion exchange method: exchange zinc ions in the composite carbon source with ion exchange resin to remove them. Ion exchange method has the advantages of good removal effect and simple operation.
4. Membrane separation method: zinc ions in the composite carbon source are separated by membrane separation technologies such as reverse osmosis and ultrafiltration, so as to be removed. Membrane separation has the advantages of good removal effect and simple operation.