CEM - Abstract

Abstract Information :

Formaldehyde (CH2O) is a chemical compound extremely common in many industrial productions; is being used like as a solvent, for make-up products, preservative (also in foods as E240), and some years ago also in medications (like the well known 'Formitrol').

Since January 2016, such compound has been re-classified as carcinogenic (H350) and mutagenic (H341), and this fact caused big limitations in emission limit of formaldehyde, down to the limit of 5 mg/Nm3.

As Formaldehyde was thought to be not very dangerous up until few years ago, no European validated method for emissions control exists, as for such lack a new working item was initiated. In the field of biomasses, importance of formaldehyde is given by its presence in emissions from spark engines that burns biomethane.

From a first examination of candidate methods, two analytical principles were selected: spectrophotometry (EPA 323) and HPLC (VDI 3862-2), using impingers with an absorption solution, as such technique is the most common also for other compounds.

Starting from these standards, an improved version of the method was implement and tested during two field trials on a biogas electrical generator. From these first test trials, some important conclusions emerge:

• the presence of condensation in the sampling line can give rise to measurement misestimating due to high formaldehyde solubility
• pure water as absorbing solution is uneffective, and is necessary to use 0,01n H2SO4 solution
• is not necessary to use DNPH to stabilise sampled solution in field, but is possible to do it within 48 hours from sampling, in laboratory
• after stabilisation with DNPH, is necessary to let samples rest for at least 24 hours, in order to let full development of stabilisation reactions
• after stabilisation, samples are stable for at least 15 days
• HPLC and spectrophotometry give similar results.