Abstract: 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.

Key words: inorganic antibacterial material, Cu bearing montmorillonite, Cu²⁺ cation exchange, antibacterial mechanism