Small crystal NaA zeolite was synthesized by a single-mode focused microwave approach with sodium silicate as the silica source and sodium meta-aluminate as the aluminum source. The crystallization time, phase composition, and morphology of the NaA zeolite were investigated. To demonstrate the antibacterial capability, Ag+ was loaded into the NaA zeolite. The amount of silver load in the zeolite was determined by atomic absorption spectrometry. The antibacterial property to Escherichia coli of the Ag-loaded zeolite was analyzed by a spectroturbidity method. Compared to the conventional hydrothermal synthesis of NaA zeolite, the crystallization time was significantly reduced in the single-mode focused microwave synthesis, from 2hr to 6 min. The size distribution of the NaA zeolite ranges from 300 to 400 nm in the single-mode focused microwave synthesis, more uniform than that of the conventional hydrothermal method. The amount of silver load reached 21.13%, and the minimum inhibitory concentration (MIC) to Escherichia coli was 10.42ppm in the Ag-loaded zeolite prepared with the carrier of the microwave synthesized NaA zeolite, so the antibacterial ability was significantly improved compared to the Ag-loaded zeolite prepared with the carrier of NaA zeolite by the conventional hydrothermal synthesis.

Keywords: single-mode focused microwave synthesis, small crystal NaA zeolite, Ag-loaded zeolite, crystallization time, antibacterial property