Reactive liquid–liquid extraction of bio-based 3-hydroxypropionic acid using a biocompatible organic phase containing a tertiary amine: A model-based approach to elucidate dominant mechanisms

•3-hydroxypropionic acid reactive extraction using a biocompatible organic phase.•Identification of main mechanisms for 3-HP reactive extraction with DDMA using FTIR.•Ion-pairing is the dominant extraction mechanism of 3-HP using didodecylmethylamine.•2:1 acid–amine complexes are formed by H-bonding for higher acid concentrations.•Good equilibrium model predictions over a typical biological concentration range.