Fluorescence response mechanism of green synthetic carboxymethyl chitosan-Eu3+ aerogel to acidic gases

Industrial waste acidic gases are huge hazards to the environment and human health, so a material that can detect and remove them is needed. In this paper, CM chitosan-Eu3+ fluorescence aerogel was prepared via a green method by combining the carboxymethyl chitosan biomass polymer with Eu3+ ions, the structure and properties of this aerogel were characterized by SEM, TG, and stress-strain curves. The coordination of Eu3+ ions and carboxymethyl chitosan was analyzed with XPS and the difference in luminescence intensity of aerogel prepared at different pH values was analyzed. The monitoring of the aerogels revealed different responses to different acidic gases, and the fluorescence intensity of the aerogel showed a linear decrease with the adsorbed hydrogen chloride gas (HCl), while acetic acid gas (HAc) enhanced fluorescence. The adsorption system of the CM chitosan-Eu3+ aerogel was simulated using pseudo-second-order kinetics, which showed that the maximum adsorption capacity of HCl is 9.16 mmol/g. The different response mechanisms of HCl and HAc gas were analyzed with FT-IR, fluorescence lifetime imaging and Judd-Ofelt theory. This fluorescence aerogel was found to have potential applications in ensuring industrial production safety.