Development of Ammonia Selectively Permeable Zeolite Membrane for Sensor in Sewer System.

Ammonia (NH3) and hydrogen sulfide (H2S) are hazardous and odorous gases. A special device that is not affected by other gases is necessary so that it can detect such gases. Zeolite membranes can separate the desired component selectively by molecular sieving and selective adsorption. LTA-, MFI-, and FAU-type zeolite membranes were prepared in this study, and the permeation and separation performances were determined for the ternary mixture of NH3, H2S, and N2 to develop an NH3 selectively permeable membrane. Although the separation factors of NH3 were high enough for the LTA-type zeolite membrane, the NH3 permeance was the lowest among the three membranes. In contrast, the FAU-type zeolite membrane with Si/Al = 1.35 showed a high enough NH3 permeance and a NH3/N2 separation factor. The membrane modification and varying the membrane composition were carried out to reduce the H2S permeance. As a result, the H2S permeance could be decreased by modification with silane coupling agents, and a separation factor of NH3 toward H2S of over 3000 was achieved.

Semi-automated bacterial spore detection system with micro-fluidic chips for aerosol collection, spore treatment and ICAN DNA detection.

A semi-automated bacterial spore detection system (BSDS) was developed to detect biological threat agents (e.g., Bacillus anthracis) on-site. The system comprised an aerosol sampler, micro-fluidic chip-A (for spore germination and cell lysis), micro-fluidic chip-B (for extraction and detection of genomic DNA) and an analyzer. An aerosol with bacterial spores was first collected in the collection chamber of chip-A with a velocity of 300 l/min, and the chip-A was taken off from the aerosol sampler and loaded into the analyzer. Reagents packaged in the chip-A were sequentially applied into the chamber. The genomic DNA extract from spore lyzate was manually transferred from chip-A to chip-B and loaded into the analyzer. Genomic DNA in chip-B was first trapped on a glass bead column, washed with various reagents, and eluted to the detection chamber by sequential auto-dispensing. Isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) with fluorescent measurement was adopted to amplify and detect target DNA. Bacillus subtilis was the stimulant of biological warfare agent in this experiment. Pretreatment conditions were optimized by examining bacterial target DNA recovery in the respective steps (aerosol collection, spore germination, cell lysis, and DNA extraction), by an off-chip experiment using a real-time polymerase chain reaction quantification method. Without the germination step, B. subtilis spores did not demonstrate amplification of target DNA. The detection of 10(4) spores was achieved within 2h throughout the micro-fluidic process.