The lab-made gas-diffusion unit (GDU) was comprised by two acrylic plates (10 cm ×2.8 cm × 4 cm) with symmetric grooves (1.5 mm deep, 1 mm wide and 7 cm long) and holes for fluid inlet and outlet.
The acrylic pieces were separated by commercially available Teflon® hydrophobic membranes (Vedaflon, Brazil) andthe conjunct was attached with four screws.