Removal of bacteria and odor gas by an alumina support catalyst and negative air ions

Abstract

Installation of high-performance filter systems in restrooms is necessary because of bacterial and odor gas contamination from feces. Presented herein is a sterilizing deodorizing filter (SDF) consisting of a negative air ion (NAI) filter and an alumina support catalyst (ASC) of copper and phosphoric acid. The Escherichia coli removal of the SDF was evaluated with three DC voltages (−3,–5, and −7kV) at the space velocities of 1.6×104, 2.8×104, and 5.6×104h−1. The performance of the SDF peaked at 99.9% at the high voltage of −7kV and the high space velocity of 6×104h−1 for bacteria removal. In addition, the average bacteria removal efficiency of the SDF was 1.2 times higher than the NAI filter alone at the space velocity of 5.6×104h−1. The gas removal performance of the NAI filter remained the same regardless of the duration of the experiment, but was very low at 16.7% for ammonia and 12.7% for hydrogen sulfide. The SDF and ASC filter maintained the removal rate of 100% for the first 15min of the experiment. However, after 300min, the gas removal efficiencies of the former were higher than those of the latter by 28.8% and 15% for ammonia and hydrogen sulfide, respectively. The reason for this phenomenon is that the ASC improves performance by increasing contact with the NAIs as a result of gas adsorption and gas removal.