Continuous organic synthesis in water around micro-orifices after flows

Water flows through micro-orifices are important because they occur in various fields, such as biology, medical science, chemistry, and engineering. We have reported in previous work that organic matter was generated in micro-orifices after water flowed through the orifice, and we proposed that the organic matter was synthesized from nonorganic materials, including CO₂ and N₂ dissolved in water from air, and water via the action of hydroxyl radicals produced by the flow through the micro-orifice. In the present study, we examined whether organic materials are produced in the water outside of the orifices in addition to that in the orifice. We used the decrease in water volume to measure the organic synthesis because water should be consumed during the synthesis, and thus the decrease in water volume should reflect the organic synthesis. We let ultrapure water containing dissolved air flow through a micro-orifice as a pre-flow, we stopped the flow, and then we measured the volume of water enclosed in the mount in which the micro-orifice was set over more than 100 h. The volume of water decreased gradually and substantially over time. We used Raman and infrared spectroscopy to analyze the residue obtained by evaporating the water present around the orifice. The residue contained organic matter, including carotenoids, amides, esters, and sugars, which were similar to those found in the membranes generated in the orifice in our previous paper, suggesting that the organic matter was synthesized in a wide region of water around the orifice as well as in the orifice. These results may be relevant to the origins of life and biology, and may lead to the development of a technology for reducing CO₂ in air, as well as applications in many scientific and engineering fields.