DE19532800A1 - UV active materials for solar water disinfection, photo=dynamic therapy (PDT) or photo=chemotherapy - Google Patents

Abstract

Colourless or coloured UV-active material (M) is used for the disinfection of microorganisms and the preserving of foodstuffs, or selective UV irradiation for health or therapeutic purposes, esp. for significantly reducing the no. of germs in drinking water in countries with high sunlight intensity. (M) is stable in the presence of UV light, has good thermal, mechanical, chemical and temp. shock resistance and is cheap to make. It also has either (i) a (relatively) high permeability in the UV region, pref. greater than about 300 nm and a high or low permeability in the visible and IR regions up to about 2.5 mu m, or it has a (relatively) high permeability in the UV-B / UV-C region and low permeability in the UV-A, visible and IR region up to about 2.5 mu m. The use of containers, pipes or covers comprising (M) for the same disinfection or UV irradiation process is also claimed. Pref. (M) is a silicate glass, pref. lime soda silicate glass comprising (wt.%): 65-75 SiO2, 0-5 Li2O, 10-20 Na2O, 0-5 K2O, 5-15 CaO, 0-7 MgO, 0-5 BaO, 0-5 B2O3, 0-5 Al2O3, 0-5 PbO, 0-5 SnO / SnO2, 0-2 NiO, 0-2 halides and 0-3 other components; or alkali silicate glass comprising (wt.%): 50-70 SiO2, 0-5 Li2O, 5-20 Na2O , 0-10 K2O, 0-10 RO (R = Mg, Ca or Ba), 0-20 B2O3, 0-5 Al2O3, 0-10 ZnO, 0-5 PbO, 0-5 SnO / SnO2, 0-2 NiO, 0-2 halides and 0-3 other components.

Description

The invention relates to UV-active materials with predominantly high permeability in UV-A / UV-B or UV-A range and optionally simultaneously low permeability in the VIS field, which is used to disinfect microorganisms and conserve life medicated, for health-promoting selective UV irradiation or for specific UV Therapies are used.

In particular, the invention relates to UV-active materials for solar treatment with Microorganisms contaminated waters in areas of high solar radiation intensity. The materials are solarisation-stable, thermal, mechanical and chemical resistant, temperature change resistant, inexpensive to manufacture and easy to handle handle. Containers, tubes or cover elements made of these materials are primarily used to improve the bacteriological drinking water quality Significantly improve sun exposure and after irradiation again to reduce incipient bacterial proliferation.

The goal of solar drinking water disinfection is to realize a drastic Germ killing in drinking water, which caused the occurrence and spreading bacterial Epidemics - especially the diarrheal diseases largely excludes.

In many Third World countries, the population is often totally unacceptable Drinking water available, the more than z. B. 10³ fecal-coliform bacteria per 100 ml contains, so that the so-called "waterborne deseases" can easily spread.

It would be a big step forward if z. For example, the number of fecal coliforms Bacteria of 10⁴ is reduced by 3 to 4 log steps through solar disinfection.

The invention also relates to UV-active materials used in artificial radiators for Disinfection of microorganisms used in air, water or other media can be.

It is known that in many arid developing countries jars formed as pitchers Drinking vessels or plastic containers with contaminated water around noon for some Hours of solar radiation are exposed to a bactericidal cleansing effect to achieve.

On the occasion of the workshop on "Solar Water Disinfection", which took place from 15.-17. August 1988 from the Brace Research Institute in Montreal, Que. Canada has been found to be essential to this simple treatment method:
A large number of pathogenic bacteria are killed or inactivated to a certain extent in clear drinking water by solar radiation when up to about two liter vessels are used ver,

• - made of transparent material, such as plastic or glass,
• - For at least 5 hours of solar radiation intensity of at least 500 W / m² get abandoned.

It was further stated that the UV radiation of the sun is the essential Inak effect and that also the visible radiation makes a certain contribution to the Inactivation makes. Studies on the wavelength-dependent disinfection effect however, the solar radiation was not available. Effective or reproducible kill rates could not be presented.  

As a result of more recent fundamental studies, it is found that, for. Legs Killing the indicator bacterium E. coli can be achieved in quartz tubes and that the Killing effect primarily by the short-wave solar radiation in the range of 320 / 350- 450 nm (Wegelin, M., et al .: J. Water SRT-Aqua Vol.43, No.3, p. 154-169 1994).

The cited investigation results of the prior art are unfavorable not comparable with each other, since the experiments under different Be radiation conditions z. B. in terms of the irradiation dose, the water volumes, the Layer thicknesses of the irradiated waters and the transmittive media used have been carried out.

Another disadvantage is that the effect of short-wave solar radiation <320 nm has not been investigated or that information on the UV transmission of the used Water tank missing.

It has been disadvantageous in tanning experiments in developing countries commercially available transparent vessels, whose spectral light transmission not enough was known or very low.

Even conducted measurements of transmittance of glass water jugs have spectral transmittance of a T _300nm result = 0%, T _300nm ~3% T _350nm ~40% and T _400nm 55%. With these z. As in countries of the Middle East used as vessels for "drinking water tanning" jugs can be achieved due to the completely inadequate UV transmission, only a very small solar treatment effect. After exposure to sunlight, the bacteria can also reproduce immediately unhindered, so that after a short time the slight killing effect is compensated again.

The jars, bottles or similar containers made of conventional transparent plastics also have too low UV permeabilities. The measurements of UV transmission on plastic bottles ( 1 liter), the z. For example, in Lebanon for "drinking water sonnation", spectral transmittances of T _300nm = 0%, T _320nm = 0%, T _350nm ~ 10% and T _400nm ~ 70%.

According to the prior art is also known that z. In countries of the Middle East's pickled vegetables - very often cucumbers - in transparent containers some Hours or days, depending on the NaCl content of the water, exposed to sunlight become. As a result, a partial killing of molds and yeasts takes place, the increases the shelf life of food. Disadvantageously, they also have this used conventional materials a significantly low UV transmission. Highly UV-transparent plastic materials are special materials that permeable special glasses are very expensive. Besides, they are either thermal (Deformation in intense sunlight), chemical (compared to cleaning agents) and mechanically unstable (not scratch- and abrasion-resistant), embrittled under UV influence, are not sufficiently resistant to solarization with regard to the high UV transmission or have too low thermal shock resistance.

Another disadvantage of all known for the solar treatment of drinking water or artificial irradiation used or usable materials is that they do not possess a property which promotes the renewed multiplication of the bacteria  Exposure for a certain period prevented or at least inhibited. That is, bacterio static materials that still act after irradiation are not known.

It is also known that especially well-dosed UV radiation in many respects can cause health-promoting effects. It can be beneficial to education of vitamin D, the skin pigmentation (browning), the wound healing, the blood pressure, the Healing process for certain colds or generally positive for the affect physical performance.

Recently, the UV radiation as so-called "photodynamic therapy" (PDT) also for Treatment of certain carcinomas applied. The therapy is that the diseased tissue relatively long-wave irradiated and previously with a Hematoporphyrinderivat (HPD), which acts as an absorber and primarily in the UV-A range - with a Maximum at about 370nm - absorbed. The absorbed in this wavelength range Energy initiates the desired healing process so that u. U. Skin Cancer, Superficial Bladder Cancer, Endobronchial Cancer, Head and Neck Cancer, Gynecological Malignant Nancies and Gastrointestinal Cancer Can Be Treated / Grossweiner, Leonard I .; The Science of Phototherapy, 1994, CRC Press, Inc., Chapter 8, p.139-150 /.

The object of the invention is the development of UV-active cost-effective Materials for the effective disinfection of microorganisms contaminated media and for health-promoting UV-A / UV-B or UV-A radiation. The materials due to their specific UV permeability especially for Solar improvement of bacteriological drinking water quality in developing countries suitable and on the other hand for the purposeful influence of the natural or artificial Radiation generated health and cosmetic effects serve.

In the disinfection of contaminated with microorganisms media is another essential object of the invention in the provision of UV-active materials, the act during the exposure so that even after the exposure, a bacterio static effect is observed. In this way, z. B. solar treated drinking water be made storable for a short time.

Another object of the invention is in the solar drinking water treatment in the additional exploitation of the synergy effect: heat - short-wave solar radiation.

The goal of the solar treatment of drinking water according to the invention consists in a extensive reduction of pathogenic microorganisms, primarily of bacteria, to Combating mainly diarrheal diseases.

The object of the invention has been described in the claims Materials and applications solved.  

It was found,

• - That the solar radiation has a significantly enhanced bactericidal effect, if with the UV-A radiation (315-380 nm) at the same time UV-B radiation components of the sun Spectrum (280-315 nm) are used. The same applies to the Reinforcement of the fungi and yeast killing effect of solar radiation. surprise By the way, the effect of the shortest-wave terrestrial solar radiation in the area around 300 nm very large, although its intensity is very low. That is, one with the solar Drinking water treatment materials must be used in addition to the high UV-A through permeability still possess high UV-B permeability. It was experimentally determined that the kill rate of E. coli is drastically increased when the UV-B through Permeability of the water vessel at 300 nm by 40% -50% is increased.
• - that the renewed bacterial proliferation in the treated drinking water in the period of about a day is significantly reduced, if one of the photoreactivation of the Bacteria inhibits or inhibits. This inhibition of the repair mechanisms of Bacteria are achieved by taking the waves required for photoreactivation Length ranges determined and eliminated from the radiation spectrum. By the elimination The photoreactivating wavelengths during exposure will also be the Bacteric killing rate further increased. (Photoreactivation is used in this In general, the light-induced reactivation of microorganisms understood - regardless of the inactivation causing wavelengths and Damage mechanisms).

It has been experimentally demonstrated that UV-active glass colored in the VIS range the kill rates are increased and the bacterial replication after exposure for 24 hours strongly reduced and thereby better results are achieved, than if one z. As quartz glass used throughout the terrestrial solar radiation area has the highest permeabilities with about 92% / Perkampus, H.H .; Encyclopedia of Spectroscopy, VCH Verlagsgesellschaft mbH, 1995, p. 109 /.

The thus prepared according to the invention drinking water can after nocturnal Cooling the next day to be drunk with much improved quality.

• - That in the realization of large mortality rates in bacteria, the UV transmission of Materials according to the invention in the range 300 nm only has to be relatively high when the Material in the VIS range is colored so that the absorption edge in the UV-A / VIS Transition region proceeds so that at λ = 400 nm only a permeability of <60% is realized.

This observation shows surprisingly that the short-wave VIS range the Killing bacteria does not promote but inhibits.

Silicate glasses with such absorption are not according to the prior art known (DE-PS 36 43 421).  

The catalogs of glass manufacturers prove that such UV-transparent silicate glasses are not offered. Representative catalogs are:
Optical Glass Filters: SCHOTT, 10081e 03952.5; Interference filter and special filter: SCHOTT 10061d 08941.0; and Optical Filters: ORIEL GmbH, 5.87; Stock products catalog, Volume 5: OPTICAL COATING LABORATORY. INC., 1994.

From the company SCHOTT z. B. becomes however with the Phospatglas UG5 a UV permeable Colored glass offered, which is one of the task of the invention close Transmission characteristic has. However, this filter glass has so little chemical resistance, that it is strong after only a few months of storage weathered. In addition, the phosphate glasses generally have the further disadvantages that when melting toxic compounds evaporate that they crystallization instable and thus to produce only limited dimensions and overall only very expensive are manoeuvrable to manufacture.

Characterized in that it was found that when colored UV-active glasses in the UV range to 300 nm at high killing rates only relatively low permeabilities are required, Two other major benefits can be effective. They are that the Glass at relatively low UV-B permeability not or not solarized unduly strongly or that the Glasgemengekosten fall because relatively large amounts of UV absorbers in the Glass may be included. This UV absorber - represented by the ever-present Iron oxide - are introduced through the glass raw materials and the glassmaking process. This means that a glass with lower UV transmission cost less and is technologically easier to melt.

• - That the coloring of the material by the strong absorption in the VIS and partially Absorption in the NIR causes a heating of the water, so that a synergetic Effect of UV radiation with the water temperature could be observed. The The smaller the wavelength of solar radiation, the greater the killing effect anything below 320 nm and the higher the water temperature is above 40 ° C.
• - that the mortality rates through additional measures of thermal insulation, the Heat exchange, the reflection of UV radiation (eg Al₂O₃ coating), the Application of photocatalysts (eg TiO₂ or Fe₂O₃ / TiO₂) or by an inhomo gene energy distribution in the water can be increased.
• - That as UV-transparent, cost-effective materials Mehrkomponentengläser, be but especially Kalknatronsilikatgläser and alkali silicate glasses, are suitable. They are as UV-active To melt glasses. Other requirements such as solarization resistance, hydro lytic resistance, mechanical and thermal resistance, thermal cycling ability to be easily deformed after melting and easy handling also fulfilled.  
• - That Kalknatronsilikatglas, z. B. commercially available container glass or AR glass or Alkali silicate glass, with effective transmittance in the range 300 / 320-380 / 390 nm in the VIS advantageous with known dyes, particularly advantageous but with about 0.3 to 2.0 wt.% Coloring nickel oxide and that the absorption edge in the UV-A / VIS transition region particularly favorable steep, if the glass little K₂O, much Na₂O or Li₂O and relatively contains large amounts of CaO and MgO. To improve the UV transmission in the UV B range defined amounts of B₂O₃ can be introduced into the glass.

In order to increase the solarization stability additionally defined quantities of special UV absorbers such as compounds of tin, lead, arsenic, antimony, cerium or other rare Earths are used.

Surprisingly, it was found that halides - especially fluorides - the Improve solarization resistance of the glass.

• - That realtiv large amounts of iron oxide in the glass can be made ineffective by reducing melting with special divalent organotin compounds without adverse side effects to a large extent, since the ultraviolet transmission disturbing Fe ³⁺ ions are reduced to less interfering Fe ²⁺ ions.
• - That the reduction of trivalent iron ions z. B. is also possible in the presence of bivalent nickel ions with special reducing agents. This is surprising since the redox potentials of Fe ³⁺ / Fe ²⁺ or of Ni ²⁺ / Ni ° in z. For example, soda lime silicate glasses are very similar at 0.47 and 0.43 respectively (Schreiber, HD; JNCS, 1985, 71, (1-3) 59-67).

However, the desired Fe ³⁺ ion reduction can also be realized in the presence of Ni ²⁺ ions only by using divalent organotin compounds.

By this solution according to the invention, it is possible by reducing melting with the special reducing agents and glasses with large Eisenoxidgehalten and z. B. Nickel oxide additives with effective UV transmission in the range 300 / 320-380 / 390 nm produce. However, this is a prerequisite for a particularly cost-effective glass production. A further advantage is that the bonds introduced via the divalent Organozinnver and stabilized Sn ²⁺ ions act more than other tin ions as stabilizers for solarization resistance.

The solarization resistance can be improved within certain limits independently of the deliberate inventive reducing melt by the addition of defined amounts of Sn ²⁺ or Sn ⁴⁺ compounds, or other UV absorber. This is achieved by designing the absorption edge in the 300 nm range such that the transmission is not extremely large. It has been the experience that no solarization occurs at relatively low transmission values in the range around 300 nm.

When divalent organotin compounds were used, it was also observed that the melt come into contact with precious metals such as platinum or platinum alloys can, without as otherwise in the reducing melting corrosion phenomena occur to destroy the precious metal devices or to reduce the UV Transmission through z. B. lead ionogenically dissolved platinum.

• - that UV-active glass with a NiO staining in the VIS with respect to the transmissions characteristic in the UV range can be designed so that only the UV-A radiation or the UV-A radiation and simultaneously transmits limited amounts of UV-B radiation become.

For the first case that the glass is transparent only to the UV-A radiation (315 nm to 380 nm) and small amounts of radiation of the VIS range, z. For example, the following improved applications are possible:
* Intensive skin pigmentation without the risk of negative side effects such as erythema production (the spectral sensitivity to erythema ends long-wave at about 315 nm) or the development of conjunctivitis (the spectral sensitivity of the conjunctivitis ends long-wave at about 315-320 nm). The intensive and trouble-free browning is achieved because the spectral sensitivity curve of the direct pigmentation is almost congruent with the transmission curve of the UV-A-active glass according to the invention.

This match also makes it possible for those tanning to serve Radiation equipment Radiation sources with lower total power consumption, higher UV-B irradiance and higher UV-B radiation power use.

* Possibility of more effective UV irradiation in UV photochemotherapy, in which the Treatment with photosensitized psoralenes followed by a UV-A irradiation that did not may be disturbed by UV-B radiation components / ecomed; Manual for lighting; Ed. Schweizerische Lichttechnische Gesellschaft, 5th edition, 1992, p. 26 /.

For the second case, that the glass for the UV-A radiation and at the same time for limited amounts of UV-B radiation is permeable, z. B. proposed the following new or improved applications:
* Use of the glass in artificial emitters - z. B. with emissions in the range 300- 400 nm for the disinfection of microorganisms. Here, spotlights with increased efficiencies and for the first time with bacteriostatic effect can be used.
* Possibility to increase the effective irradiation dose in the photodynamic therapy (PDT), as the Absorptioskurve z. B. of Hematoporphyrinderivates Photofrin corresponds approximately to the transmission curve of the glass. This eliminates side effects that can otherwise be caused by the photorradible radiation components not absorbed by Photofrin.

• - That UV-B / UV-C active glass, z. Fused quartz, the wavelengths of the UV-A / VIS Area not transmitted, z. B. by applying reflective layers, very large Kill rates of microorganisms and re-bacterial growth after strongly inhibits exposure.

embodiments Embodiment 1

There were soda-lime glasses of the specified container glass composition (in wt .-%) with an iron oxide content of 0.015 wt.% Fe₂O₃ and a NiO color additive of 1.0 % By weight melted.

The glass composition corresponds without NiO contemporary European pressed glass / Smrcek, S .: Glastechn. Ber. 65, (1992) No. 7, p. 198 /.

The glass was first melted without reducing agent addition and then with an addition of 0.08 wt.% Sn ²⁺ . The transmission curves were in the UV about bells shaped, with high permeability in the range 300 / 320-390 nm, formed.

The transmittance at 400 nm and 1 mm layer thickness was about 50% in both cases. The permeability at 300 nm was about 45% for the melt without the addition of reducing agent and 65% for Sn ^{2 +} addition.

Exemplary embodiments 2 and 3

Both glasses were melted using the following raw materials: Yota (SiO), H₃BO₃, Al (OH) ₃, CaCO₃, MgCO₃ basic, Na₂CO₃, K₂CO₃, BaCO₃, ZnO, Pb₃O₄, Sn ²⁺ (glass 2), SnO₂ (glass 3 ) and NiO. For the production of the glasses, the following melting temperatures were selected: melting at about 1350 ° C, refining at about 1450 ° C and casting at about 1300 ° C. The melts were carried out in a conventional, electrically heated laboratory melting furnace in the period of about 6 hours.

The measurement of the spectral transmission in the UV range before and after the irradiation according to a given artificial irradiation regime revealed no significant Differences.

Claims (6)

1. Colorless or colored UV-active materials for the disinfection of microorganisms and food preservation or health-promoting or therapeutic selective UV irradiation, primarily for the drastic germ reduction of microorganisms in drinking water in countries with high solar radiation intensity, characterized in that they are not only Stability, thermal and mechanical resistance, chemical resistance, thermal shock resistance and cost-effective production properties either effective high permeabilities in the UV, primarily greater than about 300 nm, in the VIS and IR to about 2.5 microns or only relatively high permeabilities in the UV, primarily 300 nm with simultaneously low permeabilities in VIS and IR up to about 2.5 μm or high or only relatively high permeabilities in UV-B / UV-C with simultaneously low permeability in UV-A, VIS and IR , 2. Materials according to claim 1, characterized in that they are characterized by one of the following complex light transmission property:

• a.) Permeabilities for colorless materials for 1mm layer thickness:
  T _{300 nm} <40%, T _{32O nm} <70% and T _{350 nm to 2.5 μm} <90%
• b.) Permeabilities for colored materials for 1mm layer thickness:
  T _{340 nm to 38 nm} <70%, T _{400 nm} <60% and T _{450 nm} <10% or -T ( _{180 nm to 315 nm} <70%, T _{320 nm to 380 nm} <70%, T _{400 nm to 450 nm} <20% and T _{500 nm to 5 μm} <70%.

3. Materials according to claim 1 and 2, characterized in that they consist of silicate glass, primarily of Kalknatronsilikatglas or alkali silicate glass, which is characterized by the following composition in wt .-% based on oxide: soda lime silicate glass SiO₂ 65-75 Li₂O 0-5 Na₂O 10-20 K₂O 0-5 CaO 5-15 MgO 0-7 BaO 0-5 B₂0₃ 0-5 Al₂O₃ 0-5 PbO 0-5 SnO / SnO₂ 0-5 NiO 0-2 halides 0-2 Other components 0-3 Alkali silicate glass SiO₂ 50-70 Li₂O 0-5 Na₂O 5-20 K₂O 0-10 RO 0-10 (RO = MgO, CaO, BaO) B₂0₃ 0-20 Al₂O₃ 0-5 ZnO 0-10 PbO 0-5 SnO / SnO₂ 0-5 NiO 0-2 halides 0-2 Other components 0-3 4. Use UV-active, UV-radiation stable, thermal and mechanical more resistant, chemically resistant, temperature change resistant and cost low producible materials with effective high permeabilities in the UV greater than 300 nm, in the VIS and IR up to approx. 2.5 μm or only high permeabilities in UV-A with simultaneously low permeabilities in the VIS and NIR as container and / or tubes and / or cover for disinfecting microorganisms and Preservation of food or health-promoting or therapeu selective UV irradiation, primarily for use in drastic Solar microbial reduction of microorganisms in high sunshine countries radiation intensity. 5. Use according to claim 4, characterized in that the used Materials consist of colorless or colored UV-active silicate glasses, which in Claim 3 are defined. 6. Use according to one of claims 1 to 5, characterized in that the materials used are used in disinfection systems which are characterized by one or more of the following features:

• a.) Devices for the additional generation of elevated temperatures in the media to be disinfected.
• b.) devices for inhomogeneous energy distribution of the electromagnetic radiation in the media to be disinfected.
• c.) devices for reflecting the electromagnetic radiation in the media to be disinfected.
• d.) devices for photocatalytic disinfection.