Partitioning characteristics of indoor VOCs on impermeable surfaces covered by film-phase DnBP and DEHP

Abstract

PAEs usually adsorb on indoor surfaces to form organic films, which could be more hazardous after enriching VOCs. Two typical PAEs, DnBP and DEHP, in the film phase, were chosen to explore the enrichment capacity of gaseous toluene, hexanol, and benzyl alcohol in this study. Exposed to gaseous VOCs less than 250 ppb, film-phase DnBP and DEHP could capture benzyl alcohol significantly and hexanol slightly from the air, respectively, while toluene was hardly absorbed in the films. Henry's law constants and partition coefficients (K) of VOCs in DnBP or DEHP films were derived, supposing films as dilute solution systems. The K value of VOC in DnBP or DEHP films was 1∼2 orders larger than the octanol-air partition coefficient (Koa), indicating that the surface film composition greatly influences VOC adsorption. Benzyl alcohol was the largest VOC component in surface films, agreeing well with the molecular dynamics simulation results. The hydroxyl and phenyl groups of benzyl alcohol molecules may be key factors in VOC enrichment. They form hydrogen bonds with the ester group and π-π stacking interaction with the phenyl group of DnBP or DEHP molecules, respectively. After enriching VOCs, film-phase PAEs could evoke combined exposure risks to human beings.