Adsorption of trimethylamine on zirconium silicate and polyethylene powder surfaces

Sorptive interactions of volatile organic compounds (VOCs) with indoor surfaces play a major role in inhalation exposure to these species. Using ZrSiO4 and polyethylene (PE) to model mineral surfaces and carpeting, respectively, the adsorption behavior of gaseous trimethylamine (TMA) was examined under conditions of 80% relative humidity (RH) in N2 and in the presence of 1000 ppm CO2 or NH3. TMA adsorption and desorption behavior were studied using attenuated total reflection infrared (ATR-IR) and X-ray photoelectron (XPS) spectroscopies. Spectral data revealed that TMA adsorbed on both surfaces in a protonated state. Stronger adsorption was observed to occur on ZrSiO4. XPS scans indicate that the “dry” ZrSiO4 surface maintains OH groups available for bonding, supporting earlier research showing that partition coefficients increase as RH decreases.