Preparation of nano‐ZnO using sonication method and its antibacterial characteristics

Abstract

The antibacterial activity of zinc oxide nanoparticles prepared by sonication method was evaluated in this paper. Effect of calcination conditions on the size and antibacterial activity of zinc oxide nanoparticles was investigated. Zinc oxide nanoparticles were characterised for purity (Thermo Gravimetric Analyzer), crystallinity and crystal size (XRD), particle size and morphology (TEM), etc. Results showed that the smallest size 8 nm could be obtained. The lethal experiments of nanocrystalline zinc oxide were evaluated on Lactobacillus plantarum. All L. Plantarum were killed after 24-h exposure at 1000 ppm. With the increase in calcination time, the lethal effect of ZnO nanoparticles was increased after 6-h exposure at 100 or 1000 ppm.

Nanosize MgO as antibacterial agent: preparation and characteristics

“…Characteristics measurement of CaO nanoparticles were described previously in our group (Shi et al, 2012;Tang and Shi, 2008;. TGA measurements were carried out using a Netzsch STA 409 apparatus.…”

“…With prolonged calcination time, the process will be achieved completely. The crystal size grows for long times at high calcination temperatures (Shi et al, 2012;Tang and Shi, 2008). Thus, large size nanoparticles can be obtained.…”

“…Thus, through controlling calcination temperature and calcination time, nano-MgO with different sizes could be obtained. (Shi et al, 2012;Tang and Shi, 2008). In order to get smallest size particles, the calcination temperature was about 410 °C and calcination time was 1.5 h.…”

“…When the heating rate of calcination is very fast, aggregation of nano ZnO happens more easily, due to urgent collapse of the intermediate. When the heating rate of calcination is low, nano MgO exists for a long time at high calcination temperatures, which will decrease production efficiency (Shi et al, 2012;Tang and Shi, 2008). So, an optimized heating rate of calcination must exist.…”

“…The chemical effect of ultrasound irradiation arises from acoustic cavitation formation, growth and collapse of microbubbles in liquid. The extremely high temperatures, pressures and cooling rate attained during cavitation lead to unique properties in the irradiated solution (Shi et al, 2012).These extreme conditions have been exploited to prepare nanoscale metal oxides (Huang et al, 2000;Wang et al, 2001), metal sulphides (Jeevanndam et al, 2000), nanocomposites and others (Rassokhin, 1998;Savrun and Toy, 1997;Aymonier et al, 2000;Davydov et al, 2001). We also tried in our lab (results not shown) the thermal decomposition method, but small nanocrystal could only be obtained under a very high stirring rate since mechanical power is used to prepare nanoparticles.…”