A New Type of Inorganic Antibacterial Material: Cu-bearing Montmorillonite and Discussion on Its Mechanism
新型无机抗菌材料:载铜蒙脱石及其抗菌机理讨论

With the raw material coming from Chifeng, the Inner Mongolia Autonomous Region, Cu bearing montmorillonite (Cu-MMT) was synthesized through cation exchange reaction. XRD analysis shows that, (001) basal spacing of montmorillonite expends from 1.544 nm to 1.588 nm after cation exchange. This indicates that Cu2+ enters interlayer position of montmorillonite as hydrated cation or composite cation. Through antibacterial experiment, it is found that Cu-MMT has strong antibacterial ability on E. coli and S. faecalis. Minimal inhibitory concentration (MIC) and killing concentration are 10 and 50 ppm respectively. The antibacterial ability of Cu-MMT is much better than that of Cu-carrying zeolite. Taking the up-to-date characterization on Cu-MMT and Cu-zeolite into account, it is clear that Cu-zeolite retains electric neutrality after cation exchange. Its antibacterial capacity relies on the amount of Cu2+ released into medium. On the other hand, Cu-MMT has residual positive charge after cation exchange. Its antibacterial ability results from two aspects, one is electrostatic attraction which makes large amount of bacterium being adhered on montmorillonite surface, the other is the same as Cu-zeolite, i.e., Cu2+ slowly released into medium which can kill bacterium. The former aspect is the main reason that Cu-MMT has better antibacterial ability than Cu-zeolite.