Influence of Mechanical and Chemical Treatment of Vermiculite on Resulting Antibacterial Activity of Organovermiculites

Grinding and acid treatment of clays modifies their surface and can significantly affect their resulting behaviour. The Mg-vermiculite was milled for 20 min using planetary ball mill Retsch. After sieving, fraction  40 μm was obtained (sample V). Half of this fraction was milled again in vertical jet mill Sturtevant (sample Vj). Parts of these milled samples were treated with HCl for 5 hours at 80°C (samples VA, VjA). Vermiculite samples with variously modified surface area were intercalated with chlorhexidine diacetate (CA) accordant with the cation exchange capacity of vermiculite. Chlorhexidine diacetate (substituted biguanidine) is used as antiseptic and/or disinfectant, and has very wide range of antibacterial activity being bactericidal or bacteriostatic against Gram-positive and Gram-negative bacteria. The antibacterial activity of prepared organoclays against Entrerococcus faecalis, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding minimum inhibitory concentration that completely inhibits bacterial growth. Antibacterial tests showed that the best antibacterial activity against all mentioned bacterial strains except Pseudomonas aeruginosa had jet milled vermiculite. The best antibacterial activity against Pseudomonas aeruginosa which is very resistant bacteria, had jet milled and acid treated vermiculite. The structures of prepared samples were characterized by X-ray diffraction and infrared spectroscopy.