Hydrogen particles and supersaturation in alkaline water from an Alkali–Ion–Water electrolyzer

Abstract

The hydrogen content in alkaline water obtained from an electrolytic flow cell was examined by measuring the diameter distribution of hydrogen microbubbles (hydrogen particles) in electrolyzed alkaline water using the dynamic light scattering (DLS) method. The influence of electrolysis conditions on the hydrogen content and the diameter distribution of hydrogen particles were also examined. The diameter of hydrogen particles changes rapidly with elapsed time after electrolysis, indicating that hydrogen particles grow to form large particles. The distribution of the particle diameter shows two peaks. The mean diameter of hydrogen particles is distributed mainly between 20 and 300 nm. The mean diameter decreases with an increasing current density up to 0.03 A dm −2. The diameter of hydrogen particles is smaller than the equilibrium diameter obtained by the concentration of dissolved hydrogen, suggesting that the electrolyzed water is a transition state from supersaturated to saturated solutions. Hydrogen exists in particles as a colloidal solution in a region of hydrogen content in electrolyzed water above 0.75 mM, which represents the saturation concentration of the dissolved hydrogen.