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Formaldehyde: Pollutant Profile

Direct answer: Formaldehyde (HCHO) is the smallest aldehyde — a polar, water-soluble oxygenate VOC. Its polarity is the key engineering fact: it adsorbs poorly on plain activated carbon, absorbs well in water (wet scrubbing), and oxidizes readily over Pt catalysts at low temperature. Treatment design therefore diverges sharply from aromatic VOC practice.

Definition and relevant properties (Literature Value)

Property Value
Formula / molar mass CH₂O / 30.03 g/mol
Boiling point −19.3 °C (gas at ambient conditions)
Water solubility High (aqueous formalin)
Polarity High — weak van der Waals interaction with hydrophobic adsorbents
Hazard Toxic, carcinogenic; strict workplace and emission limits

Industrial sources

  • Resin, adhesive and wood-panel production (urea-formaldehyde, phenolic resins)
  • Foundry and casting operations
  • Textile finishing and leather treatment
  • Disinfection and fumigation off-gas
  • Incomplete oxidation vents from chemical processes

Treatment challenges

  1. Poor fit with plain activated carbon — low molecular weight plus polarity means low equilibrium capacity; carbon systems require impregnated or chemically reactive media.
  2. High water solubility — a wet scrubber handles it, but generates a liquid waste stream that needs treatment.
  3. Low light-off on Pt — formaldehyde oxidizes at low temperature; catalyst performance is good but inlet concentration swings from batch resin processes must be handled.
  4. Polymerization tendency — formaldehyde can form paraformaldehyde deposits on cool surfaces.

Suitable materials

  • Pt oxidation catalysts — low-temperature oxidation; see VOC Catalytic Oxidation Guide.
  • Impregnated activated carbon — chemisorption media (e.g. oxidant- or amine-impregnated); see Impregnated Carbon.
  • Oxidant scrubber solutions — absorption with chemical reaction.

Suitable technologies

  • Catalytic oxidation (RCO) for continuous process vents
  • Wet scrubbing for water-soluble duty — see Wet Scrubbers
  • Impregnated-carbon adsorption for polishing or intermittent duty

Operating conditions that matter

  • Concentration profile (resin batch peaks)
  • Gas temperature (catalytic oxidation favors preheated gas; scrubber favors cool gas)
  • Humidity (helps scrubbing, hurts plain carbon)
  • Co-pollutants: phenol, methanol, other oxygenates typical of resin vents

Data type: see linked pages for classified parameter ranges. Physical constants above are Literature Value. See Data Classification.

Testing

Limitations

  • Plain activated carbon is a poor formaldehyde adsorbent; do not select it by analogy with aromatic VOC duty.
  • Scrubber liquid becomes a waste stream; check discharge permits before choosing absorption.
  • Cool, humid surfaces promote paraformaldehyde fouling.
  • Low inlet temperature below catalyst light-off requires preheating.