COVID-19 Pandemic and IITJ’s Advanced Photocatalytic Oxidation Sterilization Systems Initiatives
Ram Prakash
Innovation GalleryWhy Sterilization?
COVID-19 virus has spread rapidly throughout the world bringing an epidemic-like situation. Given the lack of an efficacious vaccine and also dangerous shortage of personal protective equipment, the global population has been hit hard by the current coronavirus outbreak. What has to be done by common people during COVID-19 pandemic, is a big question? We are hearing most of the time to develop sanitizers or sterilizers (disinfectors) for immediate relief. However, resources such as water, chemicals and energy costs are becoming more critical and judicious uses are recommended by the Centre for Disease Control and Prevention (CDC). Let us make it clear that disinfecting and sanitizing can be considered the same thing for some people particularly when knowing what to do during a time once a pandemic like COVID-19 is present. Nevertheless, the fact is that they are different from each other. While they both have the same objective to clean and decontaminate a surface by reducing the number of germs present, one is much more reliable than the other at killing germs. So, when to sanitize? Sanitizing is meant to reduce the growth of bacteria, viruses and fungi. Sanitizing is important and necessary when surfaces come into contact with food. Sanitizing is also part of most modern home appliances, such as, a laundry machine, dishwasher, etc. and sanitizing cycles are inclusive of the process. But, when to disinfect? Disinfecting is meant to ‘kill’ on the infected areas and eliminate many or all pathogenic microorganisms on the surfaces. Disinfecting is meant to help stop the spread of diseases. We should note that during this time, it is recommended worldwide to disinfect surfaces over sanitising.
Disinfecting techniques
Wet chemical processes are popularly known and many disinfectants are used alone or in combinations (e.g., hydrogen peroxide and peracetic acid) in the health-care settings. These include alcohols, chlorine and chlorine compounds, glutaraldehyde, formaldehyde, hydrogen peroxide, iodophors, ortho-phthalaldehyde, phenolics, peracetic acid, and quaternary ammonium compounds . In most cases, a given product is designed for a specific purpose and that has to be used in a certain manner. Disinfectants are not interchangeable, and improper concentrations and incorrect disinfectants can result in unnecessary costs and also a number of health issues. People have also tried other disinfecting methods, such as, heat sterilization , metals as microbicides , Ultraviolet (UV) radiation , etc. However, many surface materials cannot be heat sterilized and might be damaged by chemical disinfection. In most disinfectants, UV-light is well recognized as an effective and fastest method for inactivating microorganisms without any damage to the surface (cold technique) .
UV-light and its present limitation
Ultraviolet (UV) light is a spectrum of light just below the range visible to the human eye. The UV light is divided into four distinct spectral areas and they are Vacuum Ultraviolet (VUV) (100–200 nm), UV-C (200–280 nm), UV-B (280–315 nm) and UV-A (315–400 nm). These spectral areas are very specific. Out of these, UV-C is the most lethal range as a germicidal disinfectant that is capable of altering DNA/RNA of harmful bacteria/viruses, keeping them from reproducing. UV-C is basically absorbed by RNA and DNA bases, and can cause the photochemical fusion of two adjacent pyrimidines into covalently linked dimers, which then become non-pairing bases and can deactivate bacteria and viruses. While UV is effective at inactivating a wide range of microorganisms, there are limitations for its use. Surfaces can be blocked from the light if objects are in the way because UV operates in a ‘line-of-sight’ similar to sun light. The areas that are blocked from the UV-light are commonly known as shadow areas. Surfaces in these shadow areas do not receive adequate disinfection as UV-light does not have the ability to reflect well off surfaces. Shadow areas are typically dealt with by moving the UV-light source during the treatment to the other positions to accommodate disinfection of the surfaces blocked from UV disinfection. It is important to note that care must be exercised while using UV-light systems, e.g., UV-light should not be exposed directly to eyes, UV-light should also not be over exposed to skin, low dosages may not effectively inactivate some of the microorganisms, further dosages must be carefully defined for a particular system and process.
IIT Jodhpur Intervention
Recently IIT Jodhpur has developed an advanced photocatalytic oxidation sterilization process based on UV-light and metal oxide nanoparticles catalyst with novel geometry designs to eliminate microorganisms and any other suspended particles including VoC’s. The technology is based on a hybrid process where UV-C light and its photons interaction with nanoparticles catalyst provides an opportunity to generate hydroxyl radicals, hydro peroxides and supper oxide ions that eventually lead to enhance the inactivation process of bacteria and viruses. In fact, in the developed advanced process the lipid peroxidation can produce transient pores (through abstraction of H atoms from Hydroxyl radicals) for wall rupture of viruses and therefore the proposed methodology can be more effective for disinfection process even without movement of the UV-light assemblies in the portable geometry systems. Furthermore, UV-light does not penetrate well into organic materials, so for the best results of UV-C light, either one should use a standard cleaning of the room to remove any organic materials from surfaces or one should have additional process. In our hybrid system there is no need for a wet chemical process and the use of UV-C with metal oxide nanoparticles catalyst plates is able to mitigate the issue via dry process. The process generates active oxygen and electron-hole pairs to produce negative and positive ions in the treatment environment. When hydroxyl radicals collide with volatile organic compounds, the energetic nuclear molecules and free radicals can act to activate or directly degrade, which together can promote VOCs degradation. Odours, the source of organic pollution, can also be quickly eliminated through the developed process because the odorous gas is oxidized by the binding of reactive oxygen. The dust and pollen can also be removed from the sterilizing surfaces, which are basically combined with the ionic bonds that are generated in the advanced process.
IITJ’s APCO Sterilization System for FFRs
IITJ has developed an Advanced Photocatalytic Oxidation (APCO) Sterilization System for sterilization of medical accessories being used by Doctors and COVID-19 patient handlers. The most common respiratory protection device used in healthcare settings is the disposable N95 filtering face-piece respirator (FFR). However, infection control procedures typically call for disposable FFRs to be discarded after a single use to avoid cross-contamination. This means that a pandemic of a disease such as COVID-19, SARS CoV, Influenza would require a huge number of FFRs to protect healthcare workers from airborne transmissions. One possible way to meet the need for FFRs during a pandemic would be to reuse them and even a small number of reuses would greatly expand the available pool of disposable respirators. In the developed system two indigenous assemblies of lantern UV-light sterilization systems in combination with synergistically used metal oxide nanoparticles catalyst plates are housed within a standard Class II A2 biological safety cabinet to kill the bacteria and viruses in a portable protective environment. The developed system has been optimized for the UV-light dosages as per the CDC guidelines. This system not only eliminates bacteria and viruses but also can remove odors, noxious gases and volatile organic compounds or any other suspended particles within the mask. With the developed prototype system, one can easily prepare more than 150 masks per day for reuse. The system has been tested at All India Institute of Medical Science (AIIMS), Jodhpur.
Key features of the technology
- Bipolar lantern UV-light assemblies in combination with metal oxide nanoparticle catalysts, which maintain uniform sterilization throughout the system
- Alone UV light does not penetrate well into organic materials but this advance process can remove VoC’s or any other suspended particles in the FFR
- It can remove odors
- It overcomes shadow effects in portable protective environment
- It has control system and enabled with semi-automated operation
- It has SoP for operation of the sterilization system for FFR
IITJ’s APCOC System
IITJ has also developed an Advanced Photocatalytic Oxidation Conveyor (APCOC) System for sterilization of surfaces, such as, food packets, books, mobile phones, laptops, carry bags, courier bundles, etc. The developed sterilization method is a substitute of traditional chemicals and scrubbing agents for common people during the pandemic. This technology can also be used on some of the thick peel food items, leather items, during the packaging of herbs and seeds, etc. and may reduce the number of complete washdowns required during processing, thereby saving resources, such as, water, chemicals and energy costs. This system mitigates cross-contamination concerns, removes suspended impurities, and enhances overall quality of the daily use items. The product is under evaluation and testing for its disinfection efficiency.
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