According to Sanitary Standard for Drinking Water, the bacteria number is strictly limited, as overstep of microorganism in water is a threat to human’s health. By making reverse osmosis membrane and ultrafiltration membrane with chitosan material (positive charge), the bacteria and virus (negative charge) can be filtered, adsorbed, and killed in a natural way.
2. Eliminate organic compounds
Organic compounds such as nitrocompound, organic amino compound, and organohalogen compound could possibly cause diseases including cancer, barrenness, disorders of nervous system and immune system, and so on.
Nowadays, the chlorine products that disinfect drinking water can create chlorinated hydrocarbon such as trichloromethane, di-chlorobenzene and chlorophenol through natural chemical reactions, which are carcinogens or potential carcinogens threatening human’s health. The amino from chitosan can integrate with halids in water, which is able to efficiently eliminate trichloromethane in water. According to experiment conclusion, chitosan is much better in the performance of eliminating trichloromethane than activated carbon.
Besides, chitosan can adsorb organic matters such as phenol, polychlorinated biphenyls, pesticide, surfactant, and get rid of biopolymer substances such as protein, nucleic acid, polysaccharide, etc. The effectiveness of chitosan in lowering COD content of water gave itself the official authorization by the U.S. Environmental Protection Agency (EPA) for drinking water purification.
3. Get rid of heavy metals
Water pollution from heavy metals or other poisonous inorganic substances could cause various intoxication and diseases. The amino on C2 and hydroxy on C3 of chitosan are easy to form quaternary ammonium salt, which, through ion exchange, adsorption and chelation, can combine with the metal ions. Chitosan performs excellent in the chelation of transition metal ions. The chelation capacity degrades as follows:
Moreover, chitosan also eliminates oxyanions in water formed by transition metal ions, e.g. CrO42-, MoO43-
In a word, as a new type functional material for water purification, chitosan, with its unique molecular structure in dealingwith microorganism, organic compounds and heavy metal ions from the polluted waster water, will surely play a more and more significant role in water treatment and environmental area.