Study on the heat resistant property of Ag/4A antibacterial agent

The heat resistant property of silver-loading zeolite 4A antibacterial agent (SLZ) was investigated by heat treatment methodology. The morphological and structural changes of the specimens were characterized by using differential thermal analyzer (TG-DTA), scanning electron microscopy, and X-ray diffraction techniques. The particle size of the specimens was measured by Malvern instruments zetasizer systems, and silver content of specimens was determined by inductively coupled plasma spectrometer. Escherichia coli (E. coli) was chosen as indicators of fecal contamination to evaluate the antibacterial effect of the specimens by minimum inhibitory concentration method. The service life of the specimens was also tested. The experimental results indicated that as heat-treatment temperature increases, the particle size increases, more aggregating occurs, silver content decreases, the color of SLZ gradually changes from white to brown, and the antibacterial ability falls. The release rate of Ag+ cation from SLZ became slow after heat treatment at 400, 450, and 500°C, thus resulting in prolonged service life of SLZ. When the heat-treatment temperature approached 800°C, the collapse of SLZ structure occurred, and the crystals of SiO2 and Al2O3 were formed after recrystallization. Consequently, the heat resistant temperature of SLZ can be as high as 500°C. SLZ could be used in antibacterial plastics, antibacterial fibers, or biomedical materials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008