PHOTOCATALYTIC OXIDATION FOR INDOOR AIR QUALITY IN HOSPITAL OPERATING ROOMS: STUDY OF ISOFLURANE DEGRADATION
Résumé
The hospital is one of the most complex indoor environments, which requires special attention to ensure a healthy Indoor air Quality (IAQ). Proper IAQ is needed to ensure that hospital workers and patients are protected from hospital acquired infections and occupational diseases as well as ensuring their well-being and comfort. The operating room (OR) is one of the most demanding zones in the hospital 1 .The operating room air may contain different types of pollutants (chemical gases, biological contaminants and particulate matter) due to specific activities (disinfection, cleaning, surgical process and anesthesia). Air renewal by HVAC in hospitals is not always enough sufficient to ensure a good IAQ in ORs. Thus additional treatment devices based on processes such as filtration, UV disinfection and photocatalytic oxidation (PCO) can be used to purify the air. This research aims to evaluate how effective PCO is in the degradation or removal of isoflurane from OR, and connected rooms, indoor air. This involves studying the influence of operational parameters of PCO devices like velocity (v) and light intensity (I) on the kinetics of degradation. As PCO is known to generate intermediates, this work also involves an identification of possible intermediate compounds to assess the safety of isoflurane PCO. A 420 L multi-pass dynamic photocatalytic pilot 2 is used to carry out the PCO experiments. Isoflurane is studied with initial concentrations (C 0) ranging from 2 ppm to 10 ppm. The relative humidity is set at 50% at ambient temperature. The photocatalytic media used is Quartzel® PCO from Saint-Gobain. It consists of quartz fibers coated with TiO 2. Brunauer-Emmet-Teller (BET) surface area was measured and found to be 112 m 2 .g-1. The media was also found to have a low pressure drop of 120 Pa at 2 m.s-1 which would be beneficial for energy savings. Inlet velocities are varied between 0.4 m.s-1-1.5 m.s-1 whilst light intensity (UVC) is varied between 1-4.5 mW.m-2. Air samples in the pilot are taken on stainless steel adsorbent cartridges (carbopack B) and analyses are done offline using Thermal Desorption/Gas Chromatography coupled with Mass Spectrometry (MS) and Flame Ionization Detection (FID) to respectively identify and quantify isoflurane and possible reaction intermediates in the gas phase. Experiments performed at C 0 =10 ppm, v =1 m.s-1 and I = 4.5 mW.m-2 for photocatalysis and photolysis (UVC without media) showed that 80% of isoflurane is degraded by photocatalysis after 10 h whilst no significant photolytic degradation is observed. In these conditions and with the employed analytical methodology, no significant peaks associated with possible reaction intermediates on chromatograms were clearly displayed. References