The influence of operating conditions on the efficiency of vapor phase hydrogen peroxide in the degradation of 4-(dimethylamino)benzaldehyde

Vapor phase hydrogen peroxide (VPHP) nowadays finds more and more applications especially as a bio-decontamination agent for enclosed areas. Although this oxidizing agent logically offers a potential for the degradation of hazardous chemical contaminants, the information on the utilization within this area is very limited. The main objective of this study was to examine in detail the influence of basic operational (temperature, concentration of VPHP, relative humidity, condensation) and other conditions (e.g. amount of contaminant, the effect of UV radiation) on the efficiency of the VPHP process for the degradation of the selected model substance, i.e. 4-(dimethylamino)benzaldehyde. For this purpose, a series of different VPHP “wet” decontamination cycles (with a visible condensation) were carried out and compared. The obtained results clearly proved that VPHP could be utilized for the degradation of 4-(dimethylamino)benzaldehyde, however it was necessary to regard this process as a multi-parametric, in which all operational conditions played significant roles, while the molecular distribution of H2O and H2O2 at first constituted the key factor for a successful degradation of contaminants on the surface. In order to achieve the highest decomposition efficiency of 4-(dimethylamino)benzaldehyde by the wet VPHP process, it appeared to be necessary to decrease the initial relative humidity in the relevant enclosed area (ideally up to 5%) before the introduction of VPHP and carry out this decontamination procedure ideally at 25 °C and maintain the VPHP concentration higher than 500 ppm. Furthermore, it was found that the addition of UV radiation had a positive role on VPHP efficiency (in the best case, the degradation rate increased up to 1.5 times compared to using the sole VPHP). The monitoring of the concentration of VPHP within an enclosed facility is a good tool for the monitoring of the degradation of chemical contaminants by this agent.