Purpose: To find out more about the role of hydrogen gas bubbles in improving the
hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with
Magnesium (Mg).
Design/methodology/approach: The method used is an experimental method by first
conducting the SEM-Edx test, testing the content of the elements in the waxy layer and
observing the topographic shape on the surface of the taro leaves. Then prepare a mixture
of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro
leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40,
50, 60, 70, 80, 90 and 100%).
Findings: The results of this study found three conditions of the Alumina and Magnesium
mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the
surface structure of the rough mixed micro layer forms micro crevices, then bubbles of
hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of
the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic
properties. While the transition conditions occur when more and more hydrogen gas
bubbles along with the increasing percentage of Mg and the opposite occurs in micro
particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles
are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet
contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap
is getting narrower as the percentage of Mg increases and the formation of hydrogen gas
bubbles increases. The high level of bubble density in the micro gap closes the peaks of
the micro particles, which results in the surface tension of the droplet getting weaker. In this
weak surface tension condition, the hydrogen bubble can break through the droplet surface
tension and change its hydrophobic nature to hydrophilic.
Research limitations/implications: This research is limited to the hydrophobicity
of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in
supporting the hydrophobic nature of taro leaves (Colocasia esculenta).
Practical implications: The practical implication in this study is the use of hydrophobic
membranes which are widely applied to filtration.
Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3)
and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.
Self-organization of hydrogen gas bubbles rising above laser-etched metallic aluminum in a weakly basic aqueous solution
