History of UV-C applications: Part 2

A story full of small and big steps - and standstill.

 

Development means change and learning to walk on new paths, step by step. But development also means stumbling, going astray, and taking a break from time to time, in order to move forward with renewed strength. That absolutely sounds poetic, but it is equally true to reality, as the development of UV-C applications will show us.  For this, it is first necessary to take a closer look at two parallel research areas.

Let us first look at the year 1801. Johann Ritter, a young physicist at the University of Jena, discovers that at the end of the spectrum of visible light, some more rays are present. It’s the official discovery of ultraviolet light. 

An important step - but little is known about the effect of UV rays on organisms at this time. Even the effect of sunlight in general, seems insufficiently researched. It was not until 1878, when researchers made the exciting discovery that sunlight can kill microorganisms in food. In 1905, scientists finally agree that light in the range of about 250nm, causes the most damage to microorganisms. This is the wavelength of UV-C rays.

The second research area concerns the development of the lamp body. Gas discharge lamps have been used to generate light since the early 19th century. They consist of a glass body that is filled with gas. Through physical-chemical processes and the resulting discharge of particles, the lamp is finally ignited. With gas discharge lamps it is possible to produce precisely determinable wavelengths of light. The wavelength depends on the type of gas filled in and its degree of purity. To generate UV-C light, mercury gas is used.

The lamps used in the 19th century, however, do not allow UV radiation getting through the glass body. This is due to the material used. It changed in 1899 thanks to the chemist and physicist Richard Küch. He succeeded in producing a pure and bubble-free quartz glass. This has the advantage of allowing light in the wavelength range of UV rays to pass through. And so, in 1904, the first quartz lamp that is permeable to UV-C radiation was launched. Many steps forward, which finally lead to the first UV-C application for the treatment of water, being put into operation in Marseille, France, in 1910. That sounds like a development without missteps and setbacks?

Not at all! On the one hand, it can be assumed with great certainty that scientists and researchers needed many trials before they could be sure of their discovery or to get a lamp working properly. On the other hand, things could not have been worse for UV-C applications shortly after marketable products became available.

The ignition of the lamp was still problematic and a quick solution for this problem was not in sight. In addition, the treatment of water with chlorine gas was a competing process to UV-C applications. When a technology for the inexpensive production of chlorine gas in large quantities appeared on the market, there was no more demand for UV-C applications. 

 

Progress, missteps, standstill - often only the positive things are communicated, the downsides remain hidden. But development is not linear. The first idea is not always the successful one. The success of UV-C applications paused for some time after 1910 - but only to have a comeback strengthened and with improved technology, later.

And what does this mean for the human race? Standstill is a part of life, development and also success. The Corona pandemic has forced the whole world to pause. An unexpected and with nothing to compare state. However, if we consider this break, this standstill in our lives, as part of a development, then hope appears. Because then it becomes apparent that humans, on an individual and social level, will also learn from these difficult times and continue to develop. Because standstill and also missteps, ultimately lead to a development.