A CD TUBELET FOR THE ON-SITE AND CONTINUOUS RELEASE OF GAS AND THE METHOD THEREOF

FIELD OF INVENTION:

The invention pertains to the field of biotechnology- especially for the method of generation and safe delivery of pure gases with the use of gas-permeable polymers for its on-site generation.

BACKGROUND OF THE INVENTION:

Gases are known to be used for containment of microbiological contamination. Such gases include chlorine dioxide, sulfur dioxide, nitrogen dioxide, nitric oxide, nitrous oxide, hydrogen sulfide, hydrocyanic acid, dichlorine monoxide and the like. It also includes mixture of more than one gas like the mixture of chlorine dioxide and carbon dioxide. In particular chlorine dioxide has several applications ranging from being a disinfectant, an antiseptic and a sanitizer. Further, chlorine dioxide has been in use to disinfect water, water supplies, food and food products and also known to have other utilities for treating devices and equipment's in the medical field, food processing and packaging units. Several methods are known for the generation of chlorine dioxide. However, most of these methodologies fail to provide chlorine dioxide in pure gaseous form thus, allowing the unreacted reactants (since the reaction between sodium chlorite and acid involved in chlorine dioxide generation never reaches to 100% {approx. 80% completion}) and reaction by-products too contaminate the treated water. Pure gas release is mentioned but the packaging is relatively complicated. It is a packing of pouch inside a pouch and it requires water as a precursor. On its entry in the pouch CIO2 is generated thus, cannot be used for treating surfaces. Thus in the case of food and related industries and water decontamination process, a simple, safe and minimal residual generating method is a primary requisite. Another major problem with this gas is, it cannot be stored or transported like chlorine due to its explosive nature and therefore, requires to be generated on-site (point of use). There is another aspect to the device/apparatus in the art- that the apparatus for the preparation and delivery of gases are cumbersome, requires elaborate set-up and skilled manpower and occupy space and also adds cost. In addition, they are largely lacking the very important aspect of control release (time and dose) efficiency of reaction and purity of gas and therefore, this need to be addressed.

Thus, there exists a need for a device that can control the generation of gases in controlled manner with respect to dose, time, volume and is pure, safe and efficient, without any residual reactant or by-products and is economical.

OBJECT OF THE INVENTION

The object of the invention is for a distinct delivery device for the onsite generation and continuous generation and delivery of pure gases. Another object of the invention is the method for the controlled rate and efficiency of the reactions for a safe and efficient disinfection and decontamination using the delivery device of the invention. FIGURES AND DRAWINGS

Figure 1 shows a typical CD tubelet.

Figure 2 is the uv- visible spectrum of CD released in aqueous form from the CD tubelet. Figure 3 depicts the mechanical means of release of gas.

Figure 4 depicts the CD tubelet used for decontamination of small volumes of liquid. Figure 5 is the photomicrograph of the assessment of growth microbes after decontamination.

Figure 6 is the set up for continuous release of gas using the CD tubelet.

Figure 7 is the photomicrograph of the assessment of growth of microbes after decontamination of surfaces (vegetables).

Figure 8 is the photomicrograph of the assessment of growth of microbes after decontamination of surfaces (vegetables).

Figure 9 is the photomicrograph of the assessment of growth of microbes after decontamination of surfaces (vegetables).

Figure 10 is the photomicrograph of the assessment of growth of microbes after decontamination of metals (surgical appliances).

Figure 11 is the photomicrograph of the assessment of growth of microbes after decontamination of surfaces (sponge wipes). DESCRIPTION OF THE INVENTION

The invention is for a distinct delivery device for the on-site generation and continuous generation and delivery of pure gases. The invention is for a method for the controlled rate and efficiency of the reactions for a safe and efficient disinfection using the delivery device of the invention.

The delivery device is a tubelet (CD tubelet) of a polymer selected from a gas permeable polymer such as silicone, polyethylene, and preferably silicone but not limiting to.

The shape of the delivery device can be varied and is selected from a pouch, sheets, bullet, capsule, cassette, bottle to cater various applications.

The CD tubelet is non-toxic and the polymer does not degrade to leach out into the bulk aqueous medium.

The CD tubelet of the invention is of dimension of internal diameter in the range of 0.1 mm-45 mm; wall thickness in the range of 0.1 mm -10mm and the tube length in the range of 20 mm- 10 m.

The delivery device for the continuous release of pure gas is a gas permeable polymer preferably a silicon tubelet (CD tubelet) of dimension of internal diameter in the range of 0.5 mm-10 mm; wall thickness in the range of 0.5 mm -10mm and the tube length in the range of 1-10 m. The silicone tubelet is rolled on a rod and selected from teflon, polypropylene and polyvinyl chloride and the tubelet is wrapped around the rod to increase the surface area of the chlorine dioxide exposure in the water bulk. The reactants in the CD tubelet for the generation of decontaminating pure gases is either immobilized or packed.

The reactants packed in the CD tubelet for the generation of decontaminating pure gas is selected from liquid, solid or gas.

The aqueous media for solubilization of the solid reactants is water.

The reactants or the precursor selection for chlorite ion donor is selected from sodium chlorite, sodium chlorate and the like.

The reactants or the precursor selection for H ⁺ ion donor is selected from citric acid, phosphoric acid, hydrochloric acid and the like. The ratio of the chlorite ion donor to the H ⁺ ion donor is in the range of 1 :1 to 1 :5

The release of gas is controlled/modulated by modulating concentration or formulation of reactants or reaction media. The release of the gas is controlled by modulating the internal aqueous volume within the CD tubelet in the range of 5 μΐ to 250 ml.

The release of gas is controlled by altering the partial pressure inside the CD tubelet or outside in the bulk. The CD tubelet is gas permeable allows diffusion of gases and does not allow unreacted or other byproducts to pass through.

The gas release from CD tubelet is initiated by means of twisting, stretching, pulling a wick or any other mechanical means.

The gas is released out of the CD tubelet with the change in partial pressure from within and outside the tube. The pure gas for disinfection is selected from chlorine dioxide, sulfur dioxide, nitrogen dioxide, nitric oxide, nitrous oxide, hydrogen sulfide, hydrocyanic acid, dichlorine monoxide and preferably chlorine dioxide

The surface for decontamination with the CD tubelet of the invention is selected from air, solid surfaces or liquid.

The CD tubelet is stacked arranged, packed or molded in any form to suit the various applications. Liquid and surfaces that can be decontaminated with the CD tubelet of the invention ranges from water, plastic, glass, concrete, fabrics, fibres, wood, metals and vegetables and fruits. Further, the invention is for the method of generation and delivery of gas for disinfection comprising the step of: packing the CD tubelet with the reactants for the release of the disinfecting gas; initiating the release of disinfecting gas by mechanical means; dispensing the CD tubelet containing the reactants into the treating medium; assessment of the level of the decontamination.

The device of the invention reduces of about 10 ⁵ to 10 ⁷ CFU/ml E.coli to zero within 5-10 min of dispensation in the medium. The pH and the conductivity of the medium to be disinfected/sanitized are not altered and hence, the medium is potable.

EXAMPLES

A more clear and concise functioning of the invention is provided in the examples and drawings, which are provided for better explanation and not intended to limit the disclosure of the invention.

Example 1: Packing of the reactants in the CD tubelet:

Sodium chlorite and citric acid, in aqueous form the precursors for generation of chlorine dioxide are filled in CD tubelet (figure 1). In cases wherein, the release of the chlorine dioxide in the bulk is required to be rapid; adding calcium carbonate along with the citric acid solution can be added.

Example 2: Functioning of the CD tubelet:

The barrier in the tubelet is dislodged by pressing the barrier with fingers or the tubelet is squeezed, twisted, stretched or pulled (Figure 3) and dropped into the medium to be disinfected. The UV visible spectrum of tubelet releasing chlorine dioxide gas in milli q water is shown in Figure 2.

Example 3: Disinfection of 200 ml of water:

The CD tubelet is filled sodium chlorite solution, 150 μΐ (33 mg/ml). A pull-thread made of two different polymers is joined with each other; the thread portion in the tubelet region is made of hydrophobic polymer, which extends to other side of the tubelet joined by a thread made of hydrophilic polymer which is supersaturated with citric acid solution or hydrochloric acid (9%, w/v). Just before use, the thread is pulled from one end of the knot to the other end and is dipped in the water to be treated. The tubelet releases CIO2 in pure gas form at a concentration of about 0.2-0.8 ppm within 5-10 mins. (Figure 4)

Example 4: Disinfection of 1 liter of water:

The CD tubelet of dimension with an internal diameter of 4 mm, wall thickness of 0.8 mm and length of 40 mm was packed with 25 μϋΐεΓβ of an aqueous phase containing 0.0045 g of sodium chlorite and 0.009 g of citric acid. To start the disinfection process, the tubelet is mechanically pressed over the barrier and dropped in the water to be treated. It reduces the E.coli load 10 ^5" 10 ⁷ CFU/ml to zero within 5-10 mins. The pH and conductivity values are ± 0.1 unit and ± 4.0 μ8/α respectively. Similar results are obtained when the testing is done against P. aeruginosa and 5. aureus as the test microorganisms . Example 5: Disinfection of 5 liter of water:

The CD tubelet of dimension with an internal diameter of 3 mm, wall thickness of 2 mm, and length of 80 mm was packed with 100 μϋΐεΓβ of an aqueous phase containing 0.02 g of sodium chlorite and 0.04g of citric acid. It reduces 10 ^5" 10 ⁷ CFU/ml E.coli to zero within 10-20 mins. The pH and conductivity values are ±0.2 units and ± 2.0 μ8/α respectively.

Example 6: Disinfection of 50 L water

The CD tubelet for disinfection of 50 L is of dimension of internal diameter of 9.6 mm, wall thickness of 1.6 mm and of length 8 cm and packed with 1.6 ml of an aqueous phase of sodium chlorite 0.6 g and 1.2 g of citric acid. The silcone-based separator (lmm thickness) is placed at a distance of 2.5 cm from one end. The separator is mechanically pressed for in-situ release of chlorine dioxide and immersed in water for 16 h. The residual concentration of chlorine dioxide after 16 h of treatment was found to be 0.3 ± O.lmg/L. The pH and conductivity in the treated water was found to be ± 0.1 and ± 6.0 μ8/α respectively. To test the disinfection capability of CD-tube a mixture of 3 cultures {Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, 10 ⁵ CFU/ml) was inoculated in 50 L tap water. Total microbial count was enumerated by the following method (IS: 1622: 1981 R.2009). In the disinfected water, the microbial counts were reduced from 10 ⁵ CFU/ml to nil. Table 1 shows the water treatment data with CD-tube for both immediate and stored water after disinfection. Figure 6 shows the qualitative microbial reduction with the CD tubelet treated water. Table.1 : Table showing 50 liter water treatment with the CD-tube.

Spiked with P. aeruginosa { bulk water 10 ⁴ CFU/mi)

Spiked with P.ae ginosa, E.coli and S.aureus (bulk water 10 ⁴ CFU/ml)

Spiked with tap water culture (cells harvested from bulk) (bulk water 10 ⁴ CFU/m!)

Spiked with tap water culture (cells harvested from bulk) (bulk water 10 ³ CFU/ml)

Example 7 Disinfection of 2000 liters of water: For treatment of 2000 L tap water CD-tube comprised of sodium chlorite 2 g and hydrochloric acid 10 g dissolved each dissolved in 6ml mQ-water. Dimension of CD-tube was length 8 cm, internal diameter 40 mm and wall thickness 1 mm. The mixtures of 3 cultures (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) were inoculated in 2000 L tap water. The bacterial load was set to be 10 ⁵ CFU/ml. CD-tube was mechanically pressed for in-situ release of chlorine dioxide gas and was added in water for 30 minutes. The residual concentration of chlorine dioxide after treatment was found to be 0.7 + 0.1 mg L. The pH and conductivity values were found to be ±0.1 and ±6.0 μ8Λ;ιη respectively. Bacterial count was measured by pour plate method and complete inactivation of bacterial load was observed.

Example 8 : Continuous disinfection of water for larger volumes

In many applications continuous release of chlorine dioxide is required. Two reservoirs of the chlorine dioxide precursors namely sodium chlorite (7.5%, w/v) (A) and hydrochloric acid (9%, w/v) (B) were pumped at the flow rate 1.75 ml min. Using a T- connector, the liquids from both the tubes are allowed to mix together which traverses through a 5.3 m long silicone tubing (ID 4.8 mm x wall thickness 0.8 mm), which is rolled onto a teflon rod. The volume of acidified sodium chlorite in this tubing is 96 ml. The silicon rolled teflon rod is immersed into 500 liters of water. The TRO concentration is found to be 0.9 ppm. The set-up is shown in figure 6.

Example 9: Disinfection of air and solid surfaces:

(I) For extension of shelf-life of produce:

A) For treatment of potatoes (2 kg), the CD-tube of dimension of internal diameter of 7 mm, wall thickness of 2 mm with the length of 8 cm was packed with 2.0 ml of aqueous solution of sodium chlorite 1.0 g and citric acid 2.0 g. The exposure time was 2 h. In comparison to the untreated batch of potatoes, the treated potatoes showed complete sprout reduction and the shelf life of the potatoes was extended upto 21 days (26 °C and 72% RH in dark) (Figure 7).

B) The treatment of shallots was carried out in a similar way once in a week and the shelf life was extended upto 2 months at ambient storage conditions (26 °C and 72% RH in dark) (Figure 8). C) For treatment of tomatoes the CD-tubelet of dimension of internal diameter of 9.6 mm, wall thickness of 1.6mm with the length of 8 cm was packed with 2.0 ml of an aqueous solution of sodium chlorite 1.0 g and citric acid 2.0 g. CD- tubelet was mechanically pressed for in-situ release of chlorine dioxide and dropped in 2 L tap water. One kg of tomatoes were added in water for 60 seconds. The residual concentration of chlorine dioxide was found to be 4.2 ppm and the shelf life was extended at room temperature for 30 days at ambient storage conditions (30°C and 90% RH). Microbial count was measured by spread plate method. The treated tomatoes showed complete elimination of microbial load (Figure 9).

(II) For sterilization

A) For Sterilization of surgical instruments: The CD-tubelet of dimension of internal diameter of 9.6 mm, wall thickness of 1.6 mm and tube length of 8 cm was packed with 1.6 ml of an aqueous solution comprising of 0.6 g of sodium chlorite and 1.2 g of citric acid. Surgical instruments were contaminated with the consortium of 3 microbes {Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) for 30 minutes. The bacterial load was found to be 10 ⁵ CFU/ml. Instruments were placed in a container (5.0 L capacity) and the CD-tubelet was mechanically pressed for in-situ release of chlorine dioxide.

After 2 h microbial count was measured by sterility test. Complete inactivation of microbial load was observed (Figure 10). B) Sanitization of surfaces: For sanitization of sponge wipes CD-tubelet of dimension of internal diameter of 7mm, wall thickness of 2 mm with the length of length 4 cm was packed with an aqueous solution of 0.5 ml comprising of 0.15 g of sodium chlorite and 0.3 g of citric acid. A five day old used wipe was used, the bacterial load was found to be 10 ³ CFU/ml. CD-tubelet was mechanically pressed for in-situ release of chlorine dioxide gas and was added in container containing the wipes and exposed for 16 h. Microbial count was measured by spread plate method. Incubated plates led to complete removal of microbial load (Figure 11).

C) For sanitization of common touch point e.g., menu cards: a CD-tubelet of dimension of internal diameter of 9.6 mm, wall thickness of 1.6 mm and tube length of 8 cm was packed with 1.6 ml of an aqueous solution comprising of 0.6 g of sodium chlorite and 1.2 g of citric acid. The mixture of 3 cultures {Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) were spread on menu cards and bacterial load was found to be 10 ² CFU/ml. CD- tubelet was mechanically pressed for in-situ release of chlorine dioxide gas and was added in chamber of menu cards for 10-12 h. Microbial count was measured by spread plate method. Incubated plates led to complete inactivation of microbial load.

Advantages:

1. The invention has three distinct features, which overcomes major limitation of using CIO2 as disinfecting agent viz. ,

a. It generates in-situ CIO2 in pure GAS form. b. A modular energy independent process for treatment of various volumes. c. It does not allow unreacted reactants or reaction by products to be exposed to the treated entity and thus, not requiring other accessories to ascertain the quality of the treated.

2. Operation of the tubelet does not require skilled labor.

3. Amenable to various application with easy modification, easy to operate and scale up; economical; no space requirement for the device; quick release of gases and hence, quick disinfection; safer to handle; no by-products or residual remains percolating into the medium. Ready to use by simple mechanical means such as twisting, dropping, stretching and pulling a wick or any other force.