Generating a stream with a stable formaldehyde concentration in the laboratory

A laboratory-scale bio-trickling filter (BTF) was initialized to evaluate the removal of formaldehyde biologically. However, generating formaldehyde gas in the lab is one of the grand challenges hindering research efforts. Formaldehyde was introduced into the gaseous phase by aerating the required air flowrate through a diluted formaldehyde solution mixed with methanol as a stabilizer by a bubbler. However, achieving stable gaseous influent concentrations of formaldehyde was challenging since it polymerizes while volatilizing. Resulting in paraformaldehyde. The resulting white powder clogged the pipes and generated uneven gaseous concentrations. To solve this problem, sodium hydroxide (NaOH) was added with a phosphate buffer to the aqueous formaldehyde solution to maintain the pH between 7.00-7.20. Additionally, the aqueous solution needed to be heated at 60 °C to eliminate the polymerization. The exhausted formaldehyde by volatilization was replaced by a continuous supply of aqueous diluted formaldehyde solution to keep the volume and mass of the aqueous solution and formaldehyde constant, respectively. Stable gaseous concentration was achieved for extended periods of time and verified by Fourier transform infrared (FTIR) spectroscopy.