Fundamental studies on the intermediate layer of a bipolar membrane. Part VI. Effect of the coordinated complex between starburst dendrimer PAMAM and chromium (III) on water dissociation at the interface of a bipolar membrane

Abstract Starburst dendrimer polyamidoamine (PAMAM) is an ellipsoidal tree-like macromolecule with a well defined structure and many more amino groups than conventional macromolecules, which can be used to catalyze water dissociation in a bipolar membrane according previous work. The purpose of this research is to discover the effect of the coordinated complex between PAMAM G4 and Cr(III) on water dissociation in a bipolar membrane. The coordinated reaction between G4 and Cr(III) was investigated by UV–VIS absorption spectroscopy, and finally the molar ratio Cr(III)/G4 was chosen as 20. The I–V curves showed that the coordinated complex could be applied to accelerate water dissociation in a bipolar membrane, and the accelerative or catalytic effect was more prominent than separated G4 or Cr(III). Furthermore, the V–t curves showed that the coordinated complex in the intermediate layer was comparatively chemically stable, namely G4 had the function of fixing Cr(III) ions in the intermediate layer. Thus, it is expected that a bipolar membrane with high efficiency and comparative stability can be prepared by applying the coordinated complex between G4 and Cr(III) as the intermediate layer.