A New Power Dissipation Model and Its Analytic Formulation for Electric-Field-Driven Water Dissociation in the...

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Bipolar Polymer Membranes (BPMs) are crucial for applications like electrodialysis and CO2 capture.
• The mechanism of field-enhanced water dissociation (WD) at BPM junctions is not fully understood.
• Existing models often rely on assumptions for intense interfacial electric fields.

Purpose of the Study:

• To propose and validate a new model for field-accelerated water dissociation in BPMs.
• To elucidate the role of minority ions in power dissipation at the membrane junction.
• To provide a theoretical basis for the observed quadratic dependence of dissociation rate on electric field.

Main Methods:

• Development of a power dissipation model for water dissociation at the BPM junction.
• Analytical derivation of the dissociation rate constant's dependence on the electric field.
• Experimental validation using a commercial bipolar membrane (Fumasep® FBM).

Main Results:

• The model demonstrates that minority ions from water autoprotolysis dissipate power, enhancing heterolytic O-H bond cleavage.
• A quadratic dependence of the water dissociation rate constant on the electric field was analytically derived.
• Experimental results confirmed the predicted quadratic current-voltage trend in the BPM junction.

Conclusions:

• A power-dissipation-driven mechanism explains field-accelerated water dissociation in BPMs.
• The model accurately predicts enhancement ratios without adjustable parameters.
• This study offers a concise, falsifiable baseline for future research on BPMs and water dissociation.