Experimental Investigation on Water Adsorption Using Laser Photoacoustic Spectroscopy and Numerical Simulations

Abstract

In the present research we propose a model to assess the water vapors adsorption capacity of a SiO2 trap in the breathing circuit, aiming to reduce the loading of interfering compounds in human breath samples. In this study we used photoacoustic spectroscopy to analyze the SiO2 adsorption of interfering compounds from human breath and numerical simulations to study the flow of expired breath gas through porous media. As a result, the highest adsorption rate was achieved with a flow rate of 300 sccm, while the lowest rate was achieved with a flow rate of 600 sccm. In the procedure of H2O removal from the human breath air samples, we determined a quantity of 213 cm3 SiO2 pearls to be used for a 750 mL sampling bag, in order to keep the detection of ethylene free of H2O interference. The data from this study encourages the premise that the SiO2 trap is efficient in the reduction of interfering compounds (like water vapors) from the human breath.

Effect of Wearing Surgical Face Masks on Gas Detection from Respiration Using Photoacoustic Spectroscopy

“…So, the study evaluated the carbon dioxide and ethylene gases found in human respiration before and after wearing a surgical face mask using the CO 2 laser photoacoustic spectroscopy method with respect to CO 2 laser frequencies [ 15 , 16 , 17 , 22 , 30 , 31 , 32 , 41 , 42 , 43 ].…”

“…The photoacoustic spectroscopy gas detection used for the evaluation of the carbon dioxide and ethylene is summarized in Figure 4 and described in detail in [ 15 , 16 , 17 , 22 , 30 , 31 , 32 , 41 , 42 , 43 , 44 ].…”

“…The photoacoustic spectroscopy gas detection arrangement consists of a CO 2 laser, a lens, a chopper, a photoacoustic resonant cell, a powermeter, a lock-in amplifier, an acquisition panel, and a data-processing computer. The experimental detection system also includes a gas handling system with an essential role in the control of the studied gases, but it can also perform other actions described in detail in other articles [ 41 , 42 , 43 , 44 ]. The photoacoustic cell is an indispensable module in photoacoustic spectroscopy gas detection technology because the whole photoacoustic effect occurs in the photoacoustic cell.…”

“…In the experiments [ 15 , 16 , 17 , 22 , 30 , 31 , 32 , 41 , 42 , 43 , 44 ], the sample is enclosed in a resonant cell, where the acoustic waves are detected by four Knowles electret EK-3033 miniature microphones connected in series and mounted flush with the wall. Each microphone has a sensitivity of 20 mV/Pa and a total sensitivity of 80 mV/Pa.…”

Enhancement of photoacoustic spectroscopy with sorption enrichment for ppt-level benzene detection

“…High sensitivities well below 1 ppb can be reached with gas chromatography techniques [7], but the measurements can be time consuming and the best performance often requires offline or offsite analysis with a separate sampling step [8]. Optical methods based on spectroscopic detection are an appealing alternative [9,10]. Optical spectrometers are often more compact and more readily develop into fieldcapable instruments and autonomous onsite detectors for continuous monitoring [11].…”