Herein, we investigated the color development of the passive sampler corresponding to chlorine exposure concentration and time, which allows the general population to easily estimate their gas exposure levels. Previously, we developed a personal passive air sampler (PPAS) to estimate the exposure level to chlorine gas while using chlorinated disinfectants. Various chlorine-based disinfectants are being used during the COVID-19 pandemic however, only a few studies on exposure to harmful gases resulting from the use of these disinfectants exist. Through the calcination of LiF in the presence of cordierite, we found that cordierite thermally decomposed, and fluorine was immobilized as MgF2. In addition, we studied the immobilization of fluorine on cordierite (2MgO♲Al2O3♵SiO2), which is a matrix component of autocatalysts. Even when LiF, which is a decomposition product of the electrolytic solution (LiPF6), was used as the Li salt model, the PGM leaching rate did not significantly change. The results suggest that, when Li2CO3 was used, the Pt content was fully leached, while 94.9% and 97.5% of Rh and Pd, respectively, were leached using HCl addition. In this study, we aimed to recover PGMs via the calcination of spent automotive catalysts (autocatalysts) with Li salts based on the concept of “spent autocatalyst + waste lithium-ion batteries” and leaching with only HCl. However, since PGMs are precious metals, their dissolution requires strong oxidizing agents such as chlorine gas and aqua regia. The recovery of platinum group metals (PGMs) from waste materials involves dissolving the waste in an aqueous solution. We found that the contaminated water negatively influenced the performance of the C-H chlorination. At a higher conversion of ethylene carbonate such as 63%, the selectivity for mono-chlorinated ethylene carbonate over di-chlorinated ethylene carbonate was 86%. The 100% selectivity for single chlorination required the low conversion of ethylene carbonate such as 9%, which was controlled by limited introduction of chlorine gas. We also found that the contaminated water negatively influenced the performance of C-H chlorination. The partial irradiation of the flow channels sufficed for the C-H chlorination, which is consistent with the requirement of photoirradiation for the purpose of radical initiation. Such short time exposition sufficed the photo C-H chlorination. When ethylene carbonate was introduced to the reactor, the residence time was measured to be 15 or 30 sec, depending on the slope of the reactor to be 15 or 5 ☌, respectively. The setup employed sloped channels so as to make the liquid phase thinner, ensuring high surface to volume ratio. A novel photoflow setup designed for a gas-liquid biphasic reaction turned out to be useful for the direct use of chlorine gas in flow. We report flash C-H chlorination of ethylene carbonate, which gives chloroethylene carbonate, a precursor to ethylene carbonate.

Photoflow mix ratio