Development of gas decontamination system using thermo-responsive polymer

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Combustion gas includes several environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs) and aldehydes. They are toxic and bioaccumulative and thus have to be effectively removed. In the present study, a simple and efficient gas decontamination system was developed by the combination of the solubilization of organic pollutants to the aqueous solution of thermo-responsive polymer, the extraction based on the thermo-responsive deposit of the polymer, and collection of the polymer deposits by the flotation technique. A water-soluble polymer, poly (N-isopropylacrylamide) [PNIPAAm], having a lower critical solution temperature (ca. 32°C) was used. In the presence of PNIPAAm, PAHs in combustion gas were effectively transferred and then solubilized in the aqueous solution by passing the gas through the solution. PNIPAAm was found to act as a solubilizing agent for hydrophobic PAHs. By warming the solution, PNIPAAm was water-insoluble and deposited. Accompanying with the polyme … More r deposit, PAHs having more than three aromatic rings were predominantly collected. This was ascribed by the incorporation of PAHs into the hydrated polymer assemblies. The polymer deposits containing highly concentrated pollutants were rapidly collected on water surfaces by the flotation technique. The addition of small amounts of salt, surfactant, and ethanol was effective for improving the collection of organic pollutants and polymer deposits. Several factors including column height, polymer concentration, feeds of gas and polymer solution, temperature, air flow, etc. were investigated. The combination of the solubilization into the aqueous polymer solution and the subsequent polymer-mediated extraction was applied to the trace analysis of organic contaminants in gas samples. Because of the combination of highly sensitive fluorescent detection with polymer-mediated concentration, sub-ppb levels of aldehydes were successfully determined in the ambient air samples that had been sampled in extremely short (typically 20 s) time. The method enabled time-resolved monitoring of sub-ppb levels of organic pollutants in air. Less