a.Activated Carbon: Has a large specific surface area and strong adsorption capacity. It can adsorb various organic pollutants, heavy metal ions, and residual chlorine in water, and is widely used in the purification of drinking water and industrial water.

b.Ion Exchange Resins: Can exchange ions in water with their own functional groups. For example, cation exchange resins can remove metal cations in water, and anion exchange resins can remove anions such as sulfate and chloride, playing an important role in water softening and desalination.