Thermal Reconditioning Characteristics of a Respirator Cartridge for Organic Vapors Using Humid Air as the Desorption Gas

Abstract

Thermal Reconditioning Characteristics of a Respirator Cartridge for Organic Vapors UsingHumid Air as the Desorption Gas: Hajime HORI, et al. Department of Environmental Management, School of Health Sciences, University of Occupational and Environmental HealthObjectives: Thermal reconditioning characteristics of organic vapors from a respirator cartridge were studied by introducing humid air into a cartridge that had adsorbed organic vapors in order to develop a thermal reconditioning method. Methods: Five different organic vapors (methanol, 2-propanol, acetone, dichloromethane and methyl acetate), most of which have relatively weak adsorption affinity to charcoal, were used in this study. Adsorption was carried out at a temperature of 25°C. The relative humidity of the adsorption air with organic vapor was 50%. When the vapor concentration in the downstream of the respirator exceeded the breakthrough concentration, that is, the occupational exposure limits in Japan, the vapor supply was stopped. Then, desorption was started by introducing clean humid air from opposite side of the cartridge under a heated condition. When the desorbed vapor concentration fell below the limit of quantification, desorption process was ended and the next adsorption cycle was started after the temperature had returned to room temperature. This adsorption -desorption cycle was repeated more than three times. The desorption temperature was 65°C and the relative humidity of desorption air was 20%, 50% or 70% at 25°C. Results: When the relative humidity was 20%, the breakthrough times of regenerated cartridges were shorter than that of a new one, but no difference was observed in the breakthrough curves when the relative humidity was greater than 50%. Conclusion: The results suggest that the thermal reconditioning of respirator cartridges using humid air is possible for these vapors. (J Occup Health 2010; 52: 125-131)

Recovery of Pure Methanol from Humid Gas Using Mn–Co Prussian Blue Analogue

“…The adsorption behavior of MnHCC is consistent with that in a previous report. 15 Remarkably, MnHCC shows excellent adsorption performance below 1 kPa, with an adsorption capacity of 10.8 mmol/g of methanol at 0.43 kPa (4300 ppm), which is superior by nearly five times compared to that of AC (2.1 mmol/g).…”

“…The MnHCC exhibits a higher adsorptive capacity under a humid gas compared to that achieved in previous studies (Figure d). , Additionally, we investigated the adsorption and desorption cycles of MnHCC (Figure e); after the second cycle, the amounts and concentrations of desorbed methanol at the purification step were maintained; this was true even after 10 cycles (Figure S11), indicating the high stability of MnHCC (Figure S12).…”

“…For detoxification and material recycling, methanol needs to be removed under humid conditions using selective adsorbents. Notably, conventional adsorbents, such as activated carbon (AC) and zeolites, are inefficient in the separation of pure methanol under humid conditions or from water-based mixtures because of their low selectivity. , …”

“…Notably, conventional adsorbents, such as activated carbon (AC) and zeolites, are inefficient in the separation of pure methanol under humid conditions or from water-based mixtures because of their low selectivity. 14,15 Hence, selective methanol adsorbents play an essential role in the methanol economy. Several methanol adsorbents that utilize carbon, 16 zeolite, 17 and others porous materials 18,19 have been reported.…”