By Ed Knueve, MWS and Daniel Thomas
Many of us who have been in the water treatment industry for over 30 years have seen new technology come and go. For the most part, ‘new technology’ is just a repackaging of existing technology with a new twist. Rarely does a scientific discovery offer to fundamentally change our industry. Quantum disinfection may be exactly that; its inventors believe it will fundamentally change the way we sanitize water.
At the end of the 19th century, Joseph J. Thomson was studying cathode rays in the vaunted Cavendish Laboratory at Cambridge University when he discovered that at a low pressure the rays in question were deflected by an electric field. After subsequent tests with different gasses, he arrived at a calculation for the mass of a small, previously unknown particle. Speaking to the Philosophical Magazine of October 1897, Thomson stated: “We have in the cathode rays, matter in a new state, a state in which the subdivision of matter is carried very much farther than in the ordinary gaseous state, a state in which all matter is of one and the same kind, this matter being the substance from which all the chemical elements are made up.”
He was speaking, of course, about the electron. This infinitesimally small particle (a constituent of all matter) had profound implications for chemistry and physics in the 20th century. An atomic model using the electron was proposed by Thomson, then studied further by his student, Ernest Rutherford. Niels Bohr would later expound on the electron as part of a larger quantum theory, which is still being revised to this day. Control and manipulation of these electrons has spawned entire industries, such as microprocessing and information systems. In short, electrons are all around us. They exist in the air we breathe, the cars we drive, the computers with which we browse Facebook and in the phones we use for taking pictures.
In 2008, working out of the École des Mines in Ales, France, Cristian Chis observed electron reactions daily in his lab, while performing advanced studies in photocatalytic reactions. He had already been granted two patents for groundbreaking work. Chis’ inventions involved amorphous titanium dioxide (TiO2) deposited onto surfaces like silicon, in order to make them active under UV or sunlight. This activation created ‘electron holes’ along the surface. After a year of trial and error, he happened upon the correct approach and was able to render a new, activated surface using this new process.
Chis experimented with this new surface on a variety of substances in air, including CO2, toluene and benzene. After studying promising results, he wondered if his new surface had any properties other than what was currently being researched in photocatalysis. Namely, could this new surface be powerful enough to destroy bacteria on contact? The immediate answer was no. Initial experiments with E. coli showed promise, but contact time was an issue. The surface had germicidal properties, but took too long to eliminate bacteria. The process had to have some sort of light excitation, which involved either UV or sunlight. The idea was daunting. How could he create a surface that used no power and no chemicals, only electron attraction to kill bacteria? And more, could a supercharged surface like this even kill bacteria on contact or would the microorganism be too stable?
By 2010, Chis had researched numerous microprocessor architecture and semi-conductor studies, looking for that elusive combination that would provide the correct conductivity, in order to supercharge his electron-attracting surface. His work focused on solid-state device theory especially, which showed how electrons could be influenced by layers of conductive materials using a doping agent on silicon. But what material would be the most advanced conductor, powerful enough to rip electrons out of bacteria and onto the surface?
Chis started by using a thin gold layer deposited onto his active surface. The results showed more electron attraction, but not enough to justify the enormous cost. He then used copper. While promising, the copper layer oxidized after a few days, making the surface unworkable. Finally, after researching further into electrical conductors, Chis realized that silver was the highest conductor of electrons in the world, with a thermal conductivity reading of 420 W/m.k and an electrical conductivity reading of 62.1 (10.E6 Siemens/m), which is the highest of all metals. The biggest question was how would he attach the silver to his active surface.
Chis did not want to use silver for its bactericidal properties, but rather its conductive properties. Silver proved difficult to work with. By itself, silver can kill bacteria, but the contact time often took hours. Chis already had a surface that could kill bacteria over time. He wanted to use the conductivity of silver to supercharge his surface, making it have a complete lack of electrons. Chis tried attaching silver to his active surface with no success in the beginning. The silver leached into the water and would not stay on the surface. Added to this attachment problem, silver was expensive and each failed test incurred a cost.
In 2012, as luck would have it, Chis left a formulation of his surface (alumina catalyst supports and TiO2) in a chemical vapor deposition chamber. He had planned to deposit silver onto the surface at different pressures and temperatures before leaving his lab for the evening. He accidentally left the machine on, however, and the silver deposition lasted into the night. The next morning, the material he found had a dark blue color. Thinking he had ruined the surface, he nearly threw it out. After a brief pause, however, he decided to place the material under water. Unlike before, there was no obvious leaching of the silver. Intrigued, Chis took the small 10-gram batch to a biologist and asked to test the new surface on E. coli in small flows.
The duo arranged the trilobe-shaped material into a small column inside a PVC pipe. Using an upstream solution spiked with E. coli and a peristaltic pump, they ran water up through the small column of new material and measured the output for both silver leaching (using a photometer) and bacteria reduction (using a streak-plating method). Stunned, Chis looked at their results and realized that this new surface did not leach anything into the water. It was completely stable. Furthermore, in peristaltic flows, the surface had instantly eliminated all of the E. coli passing over it.
After nearly five years of research, Chis had discovered quantum disinfection: instant bacteria elimination through the attraction of electrons onto a surface using no power and nothing introduced into the water. But as any inventor knows, the invention itself is often the easy part. Next, Chis put his efforts into large-scale production of his new quantum disinfection surfaces, while simultaneously approaching US EPA, so that his new technology might be validated.
About the authors
Daniel Thomas is CEO of Claire Technologies, LLC of Raleigh, NC. After graduation from North Carolina State University, he started a construction company in Raleigh that focused on structural concrete repair. In 2012, Thomas and Cristian Chis co-founded Claire-Tech, the manufacturer of Silecte Quantum Disinfection Media.
About the inventor
Cristian Chis, PhD, is from Romania and was educated in France, where he