CHAPTER 2
 EFFICACY OF IODINE-TREATED BIOCIDAL FILTER MEDIA AGAINST BACTERIAL
 SPORE AEROSOLS

 Objective

 The objective of the study presented in this chapter was to evaluate the performance of an

iodine-treated biocidal filter for bacterial spores in various environmental conditions. Viable

removal efficiency (VRE), pressure drop (AP), and the viability of collected microorganisms on

the iodine-treated filter were investigated and compared with those of the untreated filter.

 Materials and Methods

Filter Media

 The iodine-treated filter (JT-70-20XP-10T-100) and untreated (JT-70-20XP-100) media

tested in this study as discs of 47-mm diameter and 2 mm in thickness were provided by

Triosyn Corp. Triiodide, prepared from stoichiometric amounts of I2 and potassium iodide

mixed with a minimum amount of water, was contacted with a quaternary ammonium anion

exchange resin to substitute the anion with triiodide. Due to the charges on the fibers, these

filters are classified as electret filters. Details of the preparation are available in the patent by

Messier (2004). The iodine concentration in effluent air passing through the iodine-treated filter

can be measured by the OSHA analytical method (ID-212) for iodine in workplace atmospheres.

The iodine sampled in the impinger medium (1.5 mMNa2CO3 and 1.5 mMNaHCO3) can be

analyzed as iodide by ion chromatography (OSHA 1994). The measured iodine concentration

was 0.004 mg 2/m3.

Test Microorganisms

 Bacillus subtilis vegetative cells were supplied by the Department of Microbiology and

Cell Sciences at the University of Florida for the production of B. subtilis spores. B. subtilis is a

Gram-positive, non-pathogenic, rod-shaped bacterium 2.0-3.0 |jm in length and 0.7-0.8 |jm in