A new absorption based CO_2 sensor based on Schiff base doped ethyl cellulose

摘要

This paper reports absorption-based CO_2 sensing of thepH-active Schiff base 2-[(2-hydroxymethylphenylimino)methyl]-5-bromo-phenol (SB) in an ethyl cellulose (EC) matrix with andwithout Teflon coating. The CO_2 sensitivity of the SB dye in the ECmatrix was evaluated in the presence of nonadecafluorodecanoic acidand tetrabutyl ammonium hydroxide. When exposed to CO_2, the sensingfilms exhibited 76% of overall relative signal change and respondedto CO_2 over a wide range: 1%-100 % (v/v). However, the slope ofthe spectral response between 1% and 5% (v/v) is more significant.The response time (au_{90}) was 15 s, and limit of detection (LOD)was 0.3% (v/v) CO_2. The stability of SB in the EC matrix wasexcellent, and when stored in the ambient air of the laboratory therewas no significant drift in signal intensity after 6 months. Ourstability tests are still in progress.