Issue link: http://winesandvines.uberflip.com/i/131907
winemaking Wineries achieve control of mold growth BY Tina Vierra C ontrol of airborne bacteria and odors on the International Space Station was achieved by use of a photocatalytic reactor invented by the National Aeronautics & Space Administration (NASA). The technology is now in public use, with many units in food-processing plants and hospitals across the United States, including more than 70 wineries in seven states (California, Michigan, Ohio, Oregon, Pennsylvania, Virginia and Washington). Is it a "mold filter"? John Hayman, director of science and technology at Akida Holdings (Kennesaw, Ga.) explains, "The unit is a photo catalytic reactor, not a filter. Unlike a filter, it can oxidize organic material and VOC gases to carbon dioxide and water vapor. When in use for the wine industry, it kills airborne mold and bacteria and removes odors." The photocatalytic process requires a specific kind of ultraviolet (UV) light and a specific form of titanium dioxide (a naturally occurring oxide of titanium with a wide application range, from paint to sunscreen and food coloring). There are several forms of titanium dioxide. A particular crystalline form of anatase phase (TiO2) is used in these units. Ultraviolet light wavelength is measured in nanometers (nm), with visible light at 400 nm. TiO2 is activated by UV from 385 nm to 180 nm. The problem with 180 nm is that it also creates ozone. The UV nm light in the photocatalytic reactor is limited to 254 nm to prevent this problem. Mechanics of the reactor A hydroxyl radical (the strongest oxidant known) is generated and held to the surface rather than becoming a gas. 3.2 eV (electron volts) from a photon in the UV light cause the TiO2 to create an electron hole—throwing off an electron that splits a water molecule. When missing an electron in its outer shell, the hydroxyl radical is very unstable—but the fact that it is surface-bound means the reactor can control it and all reactions occur on the surface of the TiO2. Nothing happens in a gaseous phase. There is no gas other than the byproducts of the TiO2 reaction, which are carbon dioxide and water vapor. Inorganic portions of the molecules are blown off. Mineralization Destruction of a mold spore (or bacteria or odor compound) uses a process called mineralization. The OH radical is like a Pac-Man. On contact with the mold spore, it takes a bite out of it, then another bite until the entire organics of the mold spore are mineralized. It holds the intermediary hydrocarbons at the surface of the TiO2, where another hydroxyl radical is going to form and further attack the spore. There is absorption on the surface of the TiO2, and the oxidation process continues until the spore is totally destroyed. This particular form of titanium dioxide is hydrophilic, so it is going to pull water to its surface. This means that any relative humidity in the air is going to be pulled naturally to its surface, which also makes the catalysts self-cleaning. This hydrophilic nanoparticle is a complete nanoparticle membrane that becomes a system. It totally coats a ratchet ring that is about 15mm long by 4mm in diameter and hollow to provide more surface area coat. The outsides, ends and centers are coated. The largest photocatalytic reactor has more than 5 square meters of surface Airocide bioconversion technology converts molds, microorganisms, pathogens, VOCs and biological gasses into harmless water vapor. area catalyst. The rings are randomly packed in the reaction chamber, much like a box of macaroni purchased from a grocery store, so that the air does not have a straight path through the reactor. In terms of relative humidity (RH), we are dealing in parts per million (ppm) —and sometimes parts per trillion (ppt). With the amount of water vapor involved, there is no condensate. Ultraviolet lamps There are 46 8-watt ultraviolet lamps in the largest photocatalytic reactor, mostly producing heat. This is the equivalent of less than three 100-watt light bulbs —very low BTU levels, but enough to increase the heat through the reactor bed. "Because we limit the speed going through the unit," explains Hayman, "we actually 'reduce' the RH as we go though the reactor bed." As heat increases, RH decreases, and the photocatalytic reaction increases. The ultraviolet lamps are separated by quartz sleeves, with coated glass rings packed between them. The quartz is used so that when a user changes the lamps (annually is recommended), they never come in contact with the reactor bed. The rings are packed in between the lamps at just the right distance to give maximum kill zone, or maximum mineralization zone. Changing off-the-shelf lamps in the latest photocatalytic reactor system requires about five minutes per machine. The photocatalytic reactors are now in their fourth generation of commercial use and development, with several upgrades made in each generation for better performance in each industry. Wineries prevent mold growth An Airocide GCS 100 bioconversion unit, mounted on the wall, eliminates high volume bio-particulate in the most extreme situations. At Bergstrom Wines (Newberg, Ore.) three photocatalytic reactors were installed and triangulated in a 2,800-square-foot barrel cellar (400 barrel capacity) in 2008. The owner was first attracted to the technolpr actica l win ery & vin eya rd JU NE 20 13 65