Abstract: Four kinds of modified montmorillonites were prepared by introducing different content of hexadecyltriphenyl phosphonium cations into sodium montmorillonite (Na/MMT) through an ion-exchange method, and characterized using thermogravimetry (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). Also the Zeta potentials and antibacterial activity of the modified montmorillonites were investigated. The onset temperatures of the decomposition for quaternary phosphonium cations in modified montmorillonites are all higher than 230℃, which have good thermal stability. For the montmorillonites, the interlayer spacings enlarge, the Zeta potentials increase and the antibacterial activity improves with the increase of the content of quaternary phosphonium cations. Na/MMT displays flake shape with the particles adhered and interwinded each other, while the modified montmorillonites are in irregular shape. QPC/MMT3 containing 23.55wt% quaternary phosphonium cations, possesses the minimal inhibitory concentration (MICs) against E.coli and S.aureus of 1.2g/L and 0.1g/L, respectively. After contacting the bacteria for 24h, 1.0g/L of QPC/MMT-3 is able to kill more than 99.9% E.coli, and nearly all the E.coli. Moreover, QPC/MMT-3 has good water resistance.

Key words: quaternary phosphonium cation, modified montmorillonite, preparation, characterization, antibacterial activity