TECHNICAL FIELD

The invention relates to a decontaminating spray for ameliorating contaminated surfaces and air, a method for the production of the decontaminating spray, a decontaminating apparatus and an electrospray nozzle assembly.

BACKGROUND

Microorganisms such as bacteria, fungi and their related spores are able to exist and remain viable outside of a host organism for significant periods of time. Whilst many species of microorganisms are non-pathogenic, sometimes forming symbiotic relations with humans, many are pathogenic. Infection caused by pathogenic microorganisms can often result by exposure of a patient to contaminated surfaces or air. Infection rate can be mitigated by the establishment of adequate contamination ameliorating measures or practices. These measures play an integral role in reducing the risk of infection in commercial sectors such as healthcare facilities and the food industry as well as private residential homes. Contamination ameliorating measures often include the use of chemical disinfectants to disinfect surfaces and air but are sometimes toxic and harmful to humans. The development of "superbugs" which are bacterial strains resistant to conventional antibiotics or disinfectants are difficult to treat. It was estimated that in 2006 as many as 70 000 deaths per year in the United States of America could be ascribed to superbugs, with up to 2 million infection related cases. Prevention against infection is thus as important as a cure. Despite intensified efforts at improving infection control programs, this figure is rising internationally with all the implications of a "silent epidemic".

In light of the prevailing dilemma, improvements in contamination ameliorating measures are required to address the cause of infections i.e. the occurrence of the microbes in atmospheres and on surfaces. The most serious occurrence is in healthcare facilities, specifically hospitals where the major microbial agents are Clostridium difficile, Escherichia coli, Pseudomonas aeruginosa, MRSA (Methicillin Resistant Staphylococcus aureus) and VRE { Vancomycin Resistant Enterococcus). The occurrence of MRSA and C. difficile were previously scarce, however, in recent times, this has risen to epidemic levels according to the World Health Organisation. Conventional disinfects are partially effective at removal of microorganisms. Free- floating P. aeruginosa and S. aureus in the atmospheres of hospital theatres and wards, if not removed, deposit on surfaces and form biofilms. These bacteria and others that form biofilms are protected by non-living components of the biofilm and respond differently to disinfectants compared to those in the free-floating state. The failure of conventional disinfectants may be ascribed to the fact that they attack single cells but remain largely ineffective in the destruction of bacteria in a biofilm state.

In addition to microorganisms, other compounds such as volatile compounds, allergens, pollutants and/or odour causing compounds can have a negative effect on human health and/or cause an unpleasant environment. The amelioration of these compounds is also of concern in private residential homes as well as commercial sectors such as healthcare facilities, factories and high-risk zones and high-care zones within facilities/factories. Whilst the major focus of this invention is related to the amelioration of microorganism contamination on surfaces and in air, other applications can include the amelioration of volatile compounds, allergens, pollutants and/or odour causing compounds.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a decontamination spray for ameliorating contaminated surfaces and air, the decontamination spray including: - a plurality of droplets having an electrostatic charge; a selected concentration of hydrogen peroxide and/or hydrogen peroxide derivative in the droplets; and a selected concentration of ozone and/or ozone derivative in the droplets. It is to be understood that the derivative/s of hydrogen peroxide or ozone may be in the form of dissociated particles thereof. These dissociated particles may be in the form of atoms, ions and/or free radicals. Examples of hydrogen peroxide dissociated particles are water and oxygen. Examples of ozone dissociated particles are oxygen, superoxide and/or singlet oxygen.

The droplets may include any suitable liquid which may be polar and/or may be capable of acting as a solvent. Typically, the liquid may be in the form of water which may be any suitable form of water such as deionised or distilled water, preferably distilled water.

It is to be further understood that the liquid of the droplets may facilitate the dissociation of hydrogen peroxide or ozone. For example, dissociation may be facilitated by hydrolysis when the liquid is or includes water.

The droplets may be nanosized, typically within the range of 1 to 100 nanometres.

For ease of reading, hereinafter for the first aspect of the invention, ozone shall refer to both ozone and/or ozone derivative/s and hydrogen peroxide shall refer to both hydrogen peroxide and/or hydrogen peroxide derivative/s.

The ozone and hydrogen peroxide may react and an oxidising agent may be synthesised, which oxidising agent may be a stronger oxidant than ozone and/or hydrogen peroxide. The oxidising agent may be in the form of hydroxyl radicals and/or trioxidane. The pH of the liquid or more particularly, the water may be selected or adjusted so as to manipulate the reaction and/or a reaction rate between the ozone and hydrogen peroxide.

A liquid pH or more particularly, a water pH of less than or equal to 7, preferably

6, may stabilise the ozone molecules and therefore, may retard, hinder or slow down the reaction rate between ozone and hydrogen peroxide. This retarded, hindered or slowed down reaction rate may reduce or limit hydroxyl radical synthesis. The oxidising agent or more particularly, trioxidane may be synthesised. The synthesis of the oxidising agent or more particularly, trioxidane may continue throughout the lifetime of the droplet as long as ozone and hydrogen peroxide are present, even when the droplet comes in contact with a surface or an airborne microorganism/contaminant.

A liquid pH or more particularly, a water pH of greater than 7 may allow for dissociation of ozone and the formation of ozone derivative/s, thereby allowing for a reaction or an increased reaction rate between ozone and hydrogen peroxide. The reaction or the increased reaction rate between ozone and hydrogen peroxide may result in the synthesis of the oxidising agent or more particularly, hydroxyl radicals. Hydroxyl radicals may remain stable when included in the nanosized water droplets, allowing for the longevity of the molecule and therefore its oxidising ability.

The electrostatic charge of the droplets may facilitate adherence of the droplets to surfaces and/or an airborne microorganism/contaminant. The electrostatic charge may also facilitate directional movement of the droplets toward surfaces, allowing for the targeted application of droplets to a specific area or surface. Adherence or directional movement of droplets on or toward surfaces may be facilitated by periodical changes in the electrostatic charge of the droplets i.e. between negative and positive electrostatic charges. The electrostatic charge may further facilitate in the adjustment of the pH of the droplets. A positive charge may promote or maintain a lower pH and a negative charge may promote or maintain a higher pH.

According to a second aspect of the invention, there is provided a method for the production of a decontaminating spray, the method including: - adjusting or selecting the pH of a liquid; introducing hydrogen peroxide and ozone in the liquid to form a mixture; and electrospraying the mixture to form droplets, which droplets have an electrostatic charge.

The liquid may be any suitable liquid which may be polar and may be capable of acting as a solvent. Typically, the liquid may be water which water may be any suitable form of water such as deionised or distilled water, preferably distilled water.

In an embodiment of the second aspect of the invention, the pH of the liquid or more particularly, the water may be adjusted to below or equal to 6, preferably within the range of 5.7 to 6. Hydrogen peroxide may be added to and mixed into the liquid or more particularly, the water to form a hydrogen peroxide solution having a concentration preferably within the range of 3 to 7mg/L. The hydrogen peroxide solution may be exposed to ozone, exposure may be at a selected temperature, typically below 30 ^Q C so as to promote inclusion of the ozone into the solution to form the mixture, wherein the mixture may have a saturated ozone concentration. Alternatively, ozone may be introduced into the hydrogen peroxide solution by synthesising ozone from the water in the hydrogen peroxide solution thereby forming the mixture. Ozone may be synthesised using any suitable conventional means, typically by using an electrolytic ozone generating (ELOG) unit. The mixture may be electro-charged so as to facilitate electrospraying. The mixture may be positively electro-charged so as to form positive electrostatically charged droplets during electrospraying of the mixture. The positive charge of the mixture and therefore the droplets may cause a decrease in the pH or may allow for the maintenance of a low pH.

The low pH may stabilise ozone in the mixture and may therefore retard, hinder or slow down a reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s in the mixture and therefore the droplets. This retarded, hindered or slowed down reaction rate may reduce or limit hydroxyl radical synthesis. An oxidising agent may be synthesised, which oxidising agent may be a stronger oxidant than ozone or hydrogen peroxide. The oxidising agent may be trioxidane.

It is to be understood that the derivative/s of hydrogen peroxide or ozone may be in the form of dissociated particles thereof. These dissociated particles may be in the form of atoms, ions and/or free radicals. Examples of hydrogen peroxide dissociated particles are water and oxygen. Examples of ozone dissociated particles are oxygen, superoxide and/or singlet oxygen. It is to be further understood that the liquid of the droplets may facilitate the dissociation of hydrogen peroxide or ozone. For example, dissociation may be facilitated by hydrolysis when the liquid is or includes water.

The electrostatic charge of the droplets may facilitate directional movement toward and may further facilitate adherence to a surface and/or an airborne microorganism/contaminant. The oxidising agent or more particularly, trioxidane may continue to be synthesised after adherence of the droplets until ozone and/or ozone derivative/s and/or hydrogen peroxide and/or hydrogen peroxide derivative/s are depleted. Due to the high oxidising ability of the oxidising agent or more particularly, trioxidane, surfaces and/or air contamination may be ameliorated in a selected space. During application of the decontaminating spray, the charge of the droplets may be manipulated. It is to be appreciated that manipulation of the charge during application may have beneficial chemistry as well as improving directional movement and/or adherence of the droplets toward and/or on surfaces by preventing repelling of droplets by a surface with the same charge.

In a second embodiment of the second aspect of the invention, the pH of the liquid or more particularly, the pH of water may be adjusted to below or equal to 6, preferably within the range of 5.7 to 6. Hydrogen peroxide may be added to and mixed into the liquid or more particularly, the water to form a hydrogen peroxide solution having a concentration preferably within the range of 8 to 10mg/L.

The hydrogen peroxide solution may be exposed to ozone, exposure may be at a selected temperature, typically below 30 ^Q C, to promote inclusion of the ozone into the solution to form the mixture, wherein the mixture may have a saturated ozone concentration. Alternatively, ozone may be introduced into the hydrogen peroxide solution by synthesising ozone from the water in the hydrogen peroxide solution thereby forming the mixture. Ozone may be synthesised using any suitable conventional means, typically by using an electrolytic ozone generating (ELOG) unit.

The mixture may be electro-charged so as to facilitate electrospraying. The mixture may be negatively electro-charged so as to form negative electrostatically charged droplets during electrospraying of the mixture. The negative charge of the mixture and therefore the droplets may cause an increase in the pH. The negative charge may increase the pH of the mixture and/or droplets by 2 on the pH scale. Typically, the negative charge may increase the pH to be within a range of 7 to 8.

This higher pH may allow for the dissociation of ozone and the formation of ozone derivative/s. A reaction between ozone and/or ozone derivative/s and hydrogen peroxide and/or hydrogen peroxide derivative/s may occur and an oxidising agent may be synthesised, which oxidising agent may be a stronger oxidant than ozone or hydrogen peroxide. A dissociation rate of ozone at a higher pH may occur faster than at a lower pH, and this may cause a faster reaction rate between ozone and/or ozone derivative/s and hydrogen peroxide and/or hydrogen peroxide derivative/s which the inventor believes may favour the synthesis of hydroxyl radicals as the oxidising agent. Hydroxyl radicals may be stable when included in the nanosized droplets allowing for the longevity of its oxidising ability.

The electrostatic charge of the droplets may facilitate directional movement toward and may further facilitate adherence to a surface and/or an airborne microorganism/contaminant. The oxidising agent or more particularly, hydroxyl radicals may continue to be synthesised after adherence of the droplets until ozone and/or ozone derivative/s and/or hydrogen peroxide and/or hydrogen peroxide derivative/s are depleted. Due to the high oxidising ability of the oxidising agent or more particularly, hydroxyl radicals, surfaces and/or air contamination may be ameliorated in a selected space. During application of the decontaminating spray, the charge of the droplets may be manipulated. It is to be appreciated that manipulation of the charge during application may have beneficial chemistry as well as improving directional movement and/or adherence of the droplets toward and/or on surfaces by preventing repelling of droplets by a surface with the same charge.

According to a third aspect of the invention, there is provided a decontaminating apparatus, which apparatus includes: - a reservoir for containing a hydrogen peroxide solution; a displacement means arranged in flow communication with the reservoir for displacing the hydrogen peroxide solution out of the reservoir; an ozone introduction means arranged to introduce ozone into the hydrogen peroxide solution thereby forming an ozone hydrogen peroxide mixture; and an electrospraying arrangement arranged in flow communication with the displacement means for electrospraying the ozone hydrogen peroxide mixture. The reservoir may be in the form of any suitable conventional chemical reactor.

The electrospraying arrangement may include a flow-by manifold and may be arranged in flow communication with the reservoir via a conduit which may be arranged to form a loop. The conduit may be in the form of any suitable conventional pipe arrangement.

The reservoir may introduce hydrogen peroxide solution into the loop, while the displacement means, which may be in the form of any suitable conventional pump, may provide the flow and pressure in the loop for electrospraying.

The ozone introduction means may be in the form of any suitable conventional electrolytic ozone generating (ELOG) unit which may be arranged in line with the conduit.

Downstream from the ELOG unit, a gas removal device may be provided which may be in the form of any suitable conventional bubble trap, with an ozone destruction catalyst so as to remove gas from the loop and to remove ozone from the gas before release to the atmosphere.

A cooling means may be provided for cooling the solution in the conduit to a temperature below 30 ^Q C, preferably within the range of 20 ^Q C to 30 ^Q C. The cooling means may be in the form of any suitable conventional peltier cooler.

The ELOG unit may be arranged downstream from the cooling means.

The electrospraying arrangement may further include an electrode positioned to charge the mixture before passing through an electrospray nozzle/s of the electrospraying arrangement. The electrode may be in the form of a stainless-steel grid. There may be provided an electrode for each of the electrospray nozzles. The charged mixture may be sprayed through the electrospray nozzle/s by means of a Taylor cone so as to produce electrostatically charged droplets.

The electrospraying arrangement may further include an extractor electrode, for facilitating the formation of nanosized droplets from the Taylor cone or a jet of a Taylor cone. In particular the extractor electrode facilitates separation of nanosized droplets from the Taylor cone or the jet of the Taylor cone. A plurality of extractor electrodes may be provided for each of the Taylor cones formed at each of the nozzles. The extractor electrodes may be configured to surround the Taylor cone or the jet of the Taylor cone thereby forming a ring. The extractor electrode may be positioned at a separation distance of 9mm from the Taylor cone or the jet of the Taylor cone or the electrode and may be arranged to be charged by an electrical source so as to be charged at an optimal voltage within the range of 1 to 3 kV. This voltage of the extractor electrode is usually lower than the voltage of the electrode thereby creating an electrical potential difference therebetween. The difference aids in the separation of the nanosized droplets from the Taylor cone or the jet of the Taylor cone.

A first control means may be provided, positioned downstream from the manifold for controlling a feed rate of the mixture supplied to the manifold and therefore the nozzle/s. The first control means may be in the form of a control valve.

A discontinuous feed system may be provided for establishing a discontinuous feed of the mixture to the electrode. The discontinuous feed system may include a timed solenoid switching valve and a feeder which may be in the form of a narrow tube which allows for the mixture to be fed to the electrode in a drop-wise manner thereby forming a discontinuous flow of the mixture to the electrode. The discontinuous flow may allow for the isolation of charged mixture to a region of the nozzle/s. The timed solenoid switching valve may be located in the flow-by manifold and the feeder may be located in a region of the nozzle/s. The feeder may have a small diameter in the range of 0.2 to 0.6mm. The feed rate may be adjusted so as to maintain a continuous Taylor cone during electrospraying.

A delivery arrangement may be provided for delivering the electrostatically charged droplets. The delivery arrangement may include an open-ended tube provided with an inline fan located at a first end region of the tube. The electrospraying arrangement is arranged to spray into the tube downstream from the fan so that the decontamination spray is expelled out of the tube by the airflow provided by the fan.

The delivery arrangement may be configured to be stationary or a handheld mobile apparatus. The decontaminating apparatus may be configured to decontaminate a volume such as a hospital ward and/ or a contaminated surface.

The delivery arrangement may include a mask and/or nasal cannula for allowing a person to inhale the decontaminating spray so as to decontaminate air breathed in and/or to decontaminate air in the lungs of the person. The mask or the nasal cannula may be arranged in flow communication with the electrospray nozzle and/or the open-ended tube via a conduit.

According to a fourth aspect of the invention, there is provided an electrospray nozzle assembly which includes: -

a porous disc allowing for the formation of a large Taylor cone.

The porous disc may be located at a terminal end region of a nozzle of an electrospraying arrangement. Any suitable fluid to be electrosprayed, may flow through the porous disc, in particular, ozonated hydrogen peroxide mixture may flow through the disc, entering through a first wall. The mixture may then seep out of the disc through a second wall, allowing for a Taylor cone to form over the entire area of the second wall of the porous disc. The large area of the porous disc and in particular the second wall of the porous disc may allow for the formation of a large diameter Taylor cone. The porous disc may be positioned within a region of a nozzle of the electrospraying arrangement such that the second wall of the porous disc may face an outside of the nozzle. The second wall may be convex, which may aid in the suspension of the Taylor cone. The large diameter Taylor cone formed on the disc, may allow for a high feed rate and therefore a high rate of spraying. The feed rate or spraying rate achieved using the disc may be within the range of 1 to 3 ml/h, typically 3ml/h. The disc may be manufactured from any suitable porous materials, such as stainless steel or ceramic.

BRIEF DESCRIPTION OF THE DRAWINGS

A method and apparatus for decontamination in accordance with the invention will now be described in more detail with reference to the accompanying drawings.

In the drawings: -

Figure 1 is a graphical representation of the depletion rate of ozone in an ozone hydrogen peroxide mixture at varying pH levels; Figure 2 is a graphical representation of the depletion rate of hydrogen peroxide in an ozone hydrogen peroxide mixture at varying pH levels;

Figure 3 is a graphical representation of hydroxyl radical concentration in an ozone hydrogen peroxide mixture at pH 5.7 when the mixture is positively or negatively electrostatically charged; Figure 4 is a graphical representation of hydroxyl radical concentration in an ozone hydrogen peroxide mixture at pH 7.5 when the mixture is positively or negatively electrostatically charged;

Figure 5 is a schematic layout of a decontaminating apparatus; and

Figure 6 is a side sectional view through an electrospraying arrangement or nozzle. DETAILED DESCRIPTION OF THE INVENTION

In accordance with a first aspect of the invention, the following is a description of an embodiment of a decontamination spray for ameliorating contaminated surfaces and air. In the embodiment, the decontamination spray includes a plurality of water droplets having an electrostatic charge, a selected concentration of hydrogen peroxide or hydrogen peroxide derivative in the water droplets and a selected concentration of ozone or ozone derivative in the water droplets.

It is to be understood that the derivative/s of hydrogen peroxide or ozone can be in the form of dissociated particles thereof. These dissociated particles can be in the form of atoms, ions and/or free radicals. Examples of hydrogen peroxide dissociated particles are water and oxygen. Examples of ozone dissociated particles are oxygen, superoxide or singlet oxygen. It is to be further understood that dissociation can be facilitated by hydrolysis by the water in the droplets.

For ease of reading, hereinafter for the first aspect of the invention, ozone shall refer to both ozone and/or ozone derivative/s and hydrogen peroxide shall refer to both hydrogen peroxide and/or hydrogen peroxide derivative/s.

The water droplets are nanosized, typically in the range of 20 to 25nm. Water forming the water droplets is typically in the form of distilled water, collected using any suitable conventional distiller apparatus.

The ozone and hydrogen peroxide which form a mixture with the water in the water droplets react and an oxidising agent is synthesised, wherein the oxidising agent is a stronger oxidant than ozone or the hydrogen peroxide. The oxidising agent can be in the form of hydroxyl radicals or trioxidane. Hydroxyl radical synthesis is usually favoured by a rapid reaction rate between ozone and hydrogen peroxide, in accordance with the well investigated peroxone process. It is believed that trioxidane synthesis is usually favoured by a slow reaction rate between ozone and hydrogen peroxide.

The pH of the water is selected or adjusted so as to manipulate the reaction rate between ozone and hydrogen peroxide in the water droplets.

A water pH of less than or equal to 6 stabilises the ozone molecules and therefore retards, hinders or slows down the reaction rate between the ozone and hydrogen peroxide, favouring the synthesis of trioxidane. The retarded, hindered or slowed down reaction rate can reduce or limit hydroxyl radical synthesis. Trioxidane synthesis continues throughout the lifetime of the droplet as long as ozone and hydrogen peroxide are present, even when the water droplet comes in contact with a surface or an airborne micro-organism/contaminant. The slow reaction between ozone and hydrogen peroxide allows for prolonged efficacy of the mixture of the droplets. The mixture remains effective for up to 30 minutes. This allows for the effective decontamination of large spaces.

A water pH greater than or equal to 7 allows for the dissociation of ozone and the formation of ozone derivative/s thereby allowing for a faster reaction rate (compared to the above) to occur between ozone and hydrogen peroxide, thereby favouring the synthesis of hydroxyl radicals as the oxidising agent. The synthesis of hydroxyl radicals can continue throughout the lifetime of the droplet as long as ozone and hydrogen peroxide are present, even when the water droplet comes in contact with a surface or an airborne micro-organism/contaminant. Hydroxyl radicals seem to remain stable when included in the nanosized water droplets, allowing for the longevity of its oxidising ability. The electrostatic charge of the water droplets facilitates adherence to surfaces and/or an airborne microorganism/contaminant. The electrostatic charge also facilitates directional movement of the droplets toward surfaces, allowing for the targeted application of the droplets to a specific area or surface.

Adherence or directional movement of droplets on or toward surfaces is further facilitated by periodical changes in the electrostatic charge of the droplets applied to the same surface i.e. between positive and negative charges. Accordingly, application of a negatively electrostatically charged spray onto a surface can negatively electrostatically charge the surface which can result in the eventual repelling between the droplets and the surface. The droplets are then given a positive electrostatic charge which will then be attracted by the negatively electrostatically charged surface and so on.

The electrostatic charge facilitates in the adjustment of the pH of the water droplets. Generally, the electrostatic charge may adjust the pH of the solution or mixture by as much as 2 on the pH scale. A positive charge may promote or maintain a lower pH and a negative charge may promote or maintain a higher pH.

In accordance with a second aspect of the invention, the following is a description of a method for the production of a decontamination spray. The method includes, adjusting or selecting the pH of a liquid in the form of water, introducing hydrogen peroxide and ozone into the water to form a mixture and electrospraying the mixture to form droplets, which droplets have an electrostatic charge.

The water is distilled water.

In an embodiment of the method, the pH of water is adjusted to 5.8. Hydrogen peroxide is added to and mixed into the water to form a solution of concentration, 5mg/L. Ozone is introduced into the hydrogen peroxide solution until saturation point is reached. The ozone is generated directly from the water in solution using an electrolytic ozone generator (ELOG). The well-documented electrolytic ozone generator generates ozone from the components of water in an electrochemical cell, eliminating the need for an oxygen gas supply, however, if so desired a separate gas supply can be used. The advantage of the ELOG is a user no longer needs to dissolve gaseous ozone into the solution when using a separate gas supply.

The mixture is positively electrostatically charged. The charged mixture is thereafter electrosprayed, by means of a Taylor cone so as to produce nanosized positively electrostatically charged droplets, which forms the decontamination spray.

The positive electrostatic charge of the mixture and therefore possibly also the droplets causes a decrease in the pH. Alternatively, the positive electrostatic charge maintains the pH of the mixture and therefore possibly also the droplets. The pH in this embodiment which is considered low, stabilises the ozone molecules in the mixture and therefore possibly also the droplets and may therefore retard, hinder or slow down the reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s in the mixture and therefore possibly also the droplets. An oxidising agent is synthesised, which oxidising agent is a stronger oxidant than the ozone, ozone derivative/s, hydrogen peroxide or hydrogen peroxide derivative/s. It is believed that the oxidising agent synthesised is in the form of trioxidane. As can be seen in figure 1 , ozone depletion at a low pH of 5.7 is the slowest indicating a slow dissociation rate of ozone. A slow dissociation rate of ozone, retards, hinders or slows down the reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s. This can be seen in figure 2, at a low pH of 5.7, hydrogen peroxide depletion is the slowest, indicating a slow reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s. The retarded, hindered or slowed down reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s, favours the synthesis of trioxidane. It is to be understood that the derivative/s of hydrogen peroxide or ozone can be in the form of dissociated particles thereof. These dissociated particles can be in the form of atoms, ions and/or free radicals. Examples of hydrogen peroxide dissociated particles are water and oxygen. Examples of ozone dissociated particles are oxygen, superoxide or singlet oxygen. It is to be further understood that dissociation may be facilitated by hydrolysis by the water in the droplets.

The electrostatic charge of the droplets allows for adherence and directional movement to and toward a surface and/or an airborne micro-organism/contaminant. Trioxidane can continue to be synthesised after adherence of the droplets until the ozone or ozone derivative/s or hydrogen peroxide or hydrogen peroxide derivative/s is depleted. Due to the high oxidising ability of trioxidane, contaminated surfaces and air in a given space are ameliorated.

In a second embodiment of the method, the pH of water is adjusted to 5.8. Hydrogen peroxide is added to and mixed into the water to form a solution of concentration, 10mg/L.

Ozone is introduced into the hydrogen peroxide solution until saturation point is reached. The ozone is generated directly from the water in solution using an electrolytic ozone generator (ELOG). The well-documented electrolytic ozone generator generates ozone from the components of water in an electrochemical cell, eliminating the need for an oxygen gas supply, however, if so desired a separate gas supply can be used. The advantage of the ELOG is a user no longer needs to dissolve gaseous ozone into the solution when using a separate gas supply.

The charged mixture is negatively electrostatically charged. The charged mixture is thereafter electrosprayed, by means of a Taylor cone so as to produce nanosized negatively electrostatically charged droplets, which forms the decontamination spray.

The negative electrostatic charge of the mixture and therefore possibly also the droplets causes an increase in the pH. The negative electrostatic charge increases the pH to approximately 7.5. At this high pH, dissociation of ozone occurs and a reaction or rapid reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s occurs and the oxidising agent is synthesised which is in the form of hydroxyl radicals. As can be seen in figure 1 , ozone depletion at higher pH values of 7.1 or 7.6, indicates an increase in the dissociation rate of ozone respectively. A higher dissociation rate of ozone, allows for a more rapid reaction between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s as compared to a lower pH. This can be seen in figure 2, at a higher pH values of 7.1 or 7.6, hydrogen peroxide depletion increases respectively, indicating a more rapid reaction rate between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s. Hydroxyl radicals, synthesised from the reaction, seem to remain stable when included in the nanosized water droplets allowing for the longevity of its oxidising ability.

The electrostatic charge may allow for adherence and directional movement of the droplets to and toward a surface and/or an airborne micro-organism/contaminant, whereupon adherence allows for the release of hydroxyl radicals synthesised. Hydroxyl radicals can continue to be synthesised after adherence of the droplets until the ozone or ozone derivative/s or hydrogen peroxide or hydrogen peroxide derivative/s is depleted. Due to the high oxidising ability of hydroxyl radicals, contaminated surfaces and air in a given space are ameliorated.

In accordance with a third aspect of the invention, the following is a description of an embodiment of a decontaminating apparatus 10. In the embodiment (as can best be seen in figure 5), the decontaminating apparatus 10 includes a reservoir in the form of a chemical reactor 12 for storing and mixing a solution of water and hydrogen peroxide, a displacement means in the form of a peristaltic pump 14 arranged in flow communication with the chemical reactor for pumping the solution out of the chemical reactor 12, an ozone introduction means in the form of an electrolytic ozone generator (ELOG) 16 arranged to introduce ozone into the solution to form an ozone hydrogen peroxide mixture, an electrospraying arrangement 18 arranged in flow communication with the peristaltic pump 14 for electrospraying the mixture and a conduit in the form of a pipe arrangement 20 for allowing fluid flow communication between the chemical reactor 12, peristaltic pump 14, ELOG 16 and the electrospraying arrangement 18.

The decontaminating apparatus 10 is arranged to form a loop 22 via the pipe arrangement 20, whereby the loop 22 is fed with hydrogen peroxide solution from the chemical reactor 12 by means of the peristaltic pump 14. The hydrogen peroxide solution is pumped through the loop 22 by the peristaltic pump 14 which provides the flow and pressure in the loop 22. The pump 14 operates by inducing peristaltic motion in a flexible region of the pipe arrangement 20, thereby preventing contact between corrosive ozone/hydrogen peroxide components and the pump parts. The peristaltic pump 14 is located downstream from the chemical reactor 12.

The ELOG 16 can be positioned at any point in the loop 22 to form the mixture before reaching the electrospraying arrangement 18 for electrospraying. Typically, the ELOG 16 is arranged and therefore positioned to be exposed to the hydrogen peroxide solution within the piping arrangement 20 between the pump 14 and the electrospraying arrangement 18. The ELOG 16 when exposed to the solution passing through the pipe arrangement 20, generates ozone directly from the water in solution. Ozone in solution reaches a saturation point, following Henry's Law. The remaining ozone in the gaseous phase is removed by a bubble trap 24 which includes an ozone destruction catalyst 26 for breaking down the removed ozone gas before release into the atmosphere. The ozone destruction catalyst 26 is selected from a list of well-known catalytic materials, for example, MnO2, mixture of CuO and Fe2O3 or activated carbon. The bubble trap 24 and ozone destruction catalyst 26 are located downstream from the ELOG 16. The ozonated hydrogen peroxide mixture is then pumped to the electrospraying arrangement 18. The spraying rate of the electrospraying arrangement 18 is equal to the feed rate by the chemical reactor 12, ensuring a constant flow rate and pressure in the loop 22.

A cooling means in the form of a conventional peltier cooler 28 is provided for cooling the solution in the pipe arrangement 20 to a temperature below 30 ^Q C. The ELOG 16 is located downstream from the cooler 28.

The electrospraying arrangement 1 8 includes a flow-by manifold 30 which flow- by manifold 30 includes a main inlet 32 and outlet 34 and a plurality of spraying outlets 36 therebetween, each of these spraying outlets 36 are in fluid flow communication with a nozzle 38. The number of spraying outlets 36 is selected according to a required density of a decontamination spray sprayed by the electrospraying arrangement 18. The flow of the mixture in the flow-by manifold 30 splits and flows through each of the spraying outlets 36, to be electrosprayed through the nozzle/s 38.

A first control means is provided downstream from the flow-by manifold 30 to control a feed rate of the mixture to the nozzle/s 38. The first control means is in the form of a control valve or more particularly a metering valve 40, capable of flow control in a ml/h range and is manufactured by corrosion resistant materials, such as Teflon or stainless-steel. The feed rate to the nozzle/s 38 is equal to the feed rate of the hydrogen peroxide solution from the chemical reactor 12 into the loop 22.

The electrospraying arrangement 18 further includes an electrode in the form of a plurality of stainless-steel grids 42, each mounted within the flow-by manifold 30 and is positioned to flank each of the spraying outlets 36 or nozzle/s 38. The stainless- steel grids 42 are connected to an electrical source (not shown) so as to allow for charging of the stainless-steel grids 42, either positively or negatively. The optimal voltage used to charge the stainless-steel grids 42 is 8 to 13 kV. The high voltage is generated from an inverter circuit, employing an oscillator IC to switch an automobile ignition coil through a MOSFET transistor switch (not shown). When charged, the stainless-steel grids 42 confer an electric charge, either positively or negatively, to the surrounding ozonated hydrogen peroxide mixture passing through the spraying outlets 36. The charging of the ozonated hydrogen peroxide mixture allows for electrospraying and the formation of nanosized droplets, using a Taylor cone (as seen in figure 6).

The electrospraying arrangement 18 further includes an extractor electrode 44 (not shown), for facilitating the formation of nanosized droplets from the Taylor cone or a jet of a Taylor cone by separation therefrom. A plurality of extractor electrodes 44 is provided for each of the Taylor cones formed at each of the nozzles 38. The extractor electrodes 44 are configured to surround the Taylor cone or the jet of the Taylor cone, thereby forming a ring. The extractor electrodes 44 are positioned to be at a separation distance of 9mm from the Taylor cone or the jet of the Taylor cone or the stainless-steel grids 42 and are arranged to be charged by an electrical source (not shown) so as to be charged at an optimal voltage of 1 to 3 kV. This voltage is usually lower than the voltage of the stainless-steel grids 42 thereby creating an electrical potential difference therebetween. The difference aids in the separation of the nanosized droplets from the Taylor cone or the jet of the Taylor cone.

A compressor 46 is provided to produce a flow of air into a compressed air manifold 48. The manifold 48 distributes the air flow into the spraying outlets 36 to assist in expelling spray droplets from the outlets 36. Compressed air from the compressed air manifold 48 flows co-axially down past the Taylor cone 60, assisting with the expulsion of spray droplets from the nozzle 38.

The electrospraying arrangement includes a discontinuous feed system which includes a timed solenoid switching valve 68 and feeder in the form of a narrow tube 70 for allowing the ozonated hydrogen peroxide mixture to be fed to the stainless-steel grids 42. The timed solenoid switching valve 68 and narrow tube 70 allows for a drop- wise feed of the mixture to the grids 42. In this way the feed creates a discontinuous flow of the mixture to the grids 42 thereby isolating the charged mixture around the grids 42 from the mixture in the rest of the loop 22. The timed solenoid switching valve 68 is located in the flow-by manifold 30 and the narrow tube 70 leads to the nozzle/s 38. The feed rate of the timed solenoid switching valve 68 is controlled so as to maintain a continuous Taylor cone.

A delivery arrangement in the form of a wand-like device 50 is provided for dispersing electrostatically charged droplets of the decontamination spray. The wandlike device 50 includes an open-ended tube 52 provided with an inline fan 54 located at a first end region of the tube 52. The electrospraying arrangement 18 is arranged to spray into the tube 52 downstream from the fan 54 so that the decontamination spray is expelled out of the tube 52 by the airflow provided by the fan 54.

In an alternate embodiment of the decontaminating apparatus, there is a second delivery arrangement (not shown) positioned inline and before the first delivery arrangement 50 to allow for the decontamination of air before entering the first delivery arrangement 50.

In an embodiment of the delivery arrangement, the wand-like device 50 is a hand-held device (not shown), connected to the rest of the apparatus which is housed in a housing. The hand-held device allows for directional spraying of specific areas, alternatively the wand-like device is mounted onto the housing, together are mobile and are remotely controlled to move to all accessible areas in a given space. It can be set to be operated using a timer, equipped with a detector to detect objects and their height in order to adjust spraying direction both vertically and horizontally.

It is to be appreciated that in order to apply the decontaminating spray to a large area, the use of external electrode/s placed in specific regions in the area can facilitate directional movement of the droplets to far regions of the area. In accordance with a fourth aspect of the invention, the following is a description of an embodiment of a nozzle assembly 56. In the embodiment, nozzle assembly 56 includes, a porous disc 58 allowing for the formation of a large Taylor cone 60.

The conductivity and surface tension of a fluid sprayed by an electrospraying arrangement 18 affects the spraying rate. The use of distilled water can be problematic when trying to achieve a high feed rate to the nozzle assembly 56 and consequently a high spraying rate. In this invention, a high feed rate and spraying rate is required so as to achieve a dense spray. Inserting the porous disc 58 into a nozzle 38 of the electrospraying arrangement 18 allows for a higher feed rate and thus a higher spraying rate. The porous disc 58 is located within a flow-by manifold 30 of the electrospraying arrangement 18, positioned at an end region of a spraying outlet 36 of the manifold 30 and specifically at a terminal end region of the nozzle 38. Any suitable fluid to be electrosprayed can flow through the disc 58, in particular, an ozonated hydrogen peroxide mixture flows through the disc 58, entering through a first wall 62. The solution seeps out of the disc 58 through a second wall 64, allowing for a Taylor cone 60 to form over the entire area of the second wall 64. The large area of the disc 58 and second wall 64 which is typically 5mm in diameter, allows for the formation of a large diameter Taylor cone 60. The second wall 64, facing the outside of the nozzle 38 is convex, which aids in the suspension of the Taylor cone 60. The large Taylor cone 60 formed due to the disc 58, allows for a high feed rate and therefore a high rate of spraying. The feed rate or spraying rate achieved using the disc 58 is within the range of 1 to 3 ml/h, typically 3 ml/h. This allows for Taylor cones 60 of approximately 20 to 25nm in size to be generated at a rate of 2x10 ¹⁵ per nozzle per hour. The disc 58 is manufactured from ceramics material.

Reactive oxygen species (ROS) are characteristically unstable molecules that readily oxidise other organic or inorganic molecules/compounds so as to reach a stable state. Exogenous oxidation of micro-organisms existing in a planktonic or a biofilm state can lead to the breakdown of key components of their surrounding features such as the cell wall, plasmalemma and/or extra cellular polymeric substances. Such breakdown often results in the death of the microorganism. Peroxone process/es, a well investigated reaction between ozone or ozone derivative/s and hydrogen peroxide or hydrogen peroxide derivative/s synthesises hydroxyl radicals or trioxidane. These products have high oxidation abilities and thus act as powerful decontaminating agents.

The applicant believes that the invention provides an effective decontamination apparatus and method for the amelioration of contaminated surfaces and air. The decontamination spray appears to be safe to breathe, requires a shorter application time and leaves no residue after application. The strong oxidation properties of the decontamination spray make it suitable to decontaminate both microbes, biomatter and organic molecules which may be harmful such as chemical and biological warfare agents. The apparatus can be configured to continuously or intermittently decontaminate rooms such as hospital wards to kill surface microbes and airborne microbes such as tuberculosis and others. A mobile handheld apparatus can be used to decontaminate any surface or airspace when needed such as rooms, equipment, vehicles and the like. The apparatus and method may be adapted to decontaminate and/or sanitize air to make it safe for breathing.

It is to be appreciated, that the invention is not limited to any specific embodiment/configuration as hereinbefore generally described and/or illustrated and may be varied as desired.