Change of antibacterial activity with oxidation of ZnS powder

The antibacterial activities of samples prepared from oxidation of ZnS powd er were studied by measuring the change in electrical conductivity with the growth of Escherichia coli, Oxidation of ZnS occurred at above 550 degrees C in air and then the amount of ZnO increased with increasing the oxidizin g temperature. The obtained crystal structure of ZnO was a zinc-blende type . From results of antibacterial tests on ZnS powder samples before and afte r oxidation, the antibacterial activity was found to increase with increasi ng the oxidizing temperature. However, no activity of ZnS was observed, irr espective of the powder concentration. The pH value after dispersing the po wder samples in physical saline solution was in the range between 5.5 and 8 .0, increasing with the formation of ZnO.