Abstract
Hydrogen chloride (HCl) gas is highly toxic to the human body. Therefore, HCl gas detection sensors should be installed at workplaces where trace HCl gas is continuously generated. Even though various polymer-based HCl-gas-sensing films have been developed, simpler and novel sensing platforms should be developed to ensure the cost effectiveness and reusability of the sensing platforms. Therefore, we present a simple strategy to fabricate reusable HCl-gas-sensing platforms using aminated polystyrene (a-PS) colloids and investigate their sensitivity, reusability, and selectivity using a quartz crystal microbalance (QCM). The reusable a-PS(1.0) colloidal sensor with a high degree of amination (DA) exhibited the highest binding capacity (102 μg/mg) based on the frequency change (Δf) during the HCl gas adsorption process. Further, its sensitivity and limit of detection (LOD) were 3.88 Hz/ppm and 5.002 ppm, respectively, at a low HCl gas concentration (<10 ppm). In addition, the sensitivity coefficient (k*) of the a-PS(1.0) colloid sensor with respect to HCHO was higher than that in the case of HF because of the lower binding affinity of the former with the a-PS(1.0) colloids. Based on these results, highly sensitive and reproducible a-PS colloids could be reused as an HCl-gas-sensing platform and used as an HCl sorbent in a gas column filter.
Highlights
The corrosive white fumes of hydrogen chloride (HCl) are generated through contact with water vapor, and HCl gas is commonly expelled into the natural environment because of the combustion of plastics, i.e., polyvinyl chloride (PVC) [1]
The PS colloidal beads were synthesized based on the synthesis method described in a previous report [18,19]
The degree of nitration (DN) of the PS colloids was approximately 1 when the mixture exhibited ratios of more than 1:1, indicating that the styrene repeating units of the PS colloids were completely substituted into the nitro groups (–NO2 )
Summary
The corrosive white fumes of hydrogen chloride (HCl) are generated through contact with water vapor, and HCl gas is commonly expelled into the natural environment because of the combustion of plastics, i.e., polyvinyl chloride (PVC) [1]. Exposure to high concentrations of HCl gas can considerably affect the human body, including the mucous membranes, eyes, and skin. Various gas-sensing materials in which a semiconductor metal oxide is used have been studied [2,3]; polymer-based gas-sensing materials are highly attractive for fabricating highly sensitive and selective gas systems because of the wide selection of chemical structures and simple film deposition. The development of HCl gas sensors, such as polyaniline (PANI) nanofiber [4] and nanofibrous porphyrinated polyimide (PPI) membrane [5], has been considerably investigated. The porphyrin derivatives in biodegradable or doped polymer [6,7], copolymer [8], or sol–gel composite [9] and TiO2 films [10] have been used as optical/optochemical sensors. Alternative copolymerization of oligo(p-phenyleneethynylene) (OPE) has been reported with respect to fluorescent sensing systems [11]
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