Michael Cochran

Business Development Manager

Engelhard Corporation

1. Introduction

1.1 Overview

This technology update outlines Engelhard’s chlorine dioxide-based technology embodied in Aseptrol® antimicrobial, -- its properties, method of operation, applications and benefits. This paper will give business development and marketing managers in consumer product companies an understanding of Engelhard’s strategic approach to the chlorine dioxide market.

1.2 The Market Opportunity

Chlorine dioxide, a water-soluble gas, is an extremely effective and powerful biocide that has been used for many years, exhibiting rapid kill over a wide range of organisms. It does not form chlorinated molecules in the presence of organics and is efficacious over a wide pH range.

Although chlorine and chlorine dioxide share the word “chlorine” in their names, their chemistries are very different. Unlike chlorine, chlorine dioxide doesn’t chlorinate. It works through oxidation and penetrates bacteria cell walls and reacts with vital amino acids in the cytoplasm of the cell to kill the organism.

However, for most applications, chlorine dioxide must be produced and used at the same location because the compound is unstable and in large quantities cannot be stored or transported. Instead, on-site chemical or electrochemical generation is required. Most often this is accomplished by reacting hazardous pre-cursers, such as concentrated sodium chlorite solutions with chlorine gas and/or hydrochloric acid, to generate chlorine dioxide.

Significant capital and operating costs have limited the use of chlorine dioxide to large-scale applications. Also, strict hazardous materials handling procedures may be required. This approach is often impractical for small-scale applications. Engelhard Aseptrol antimicrobial offers a cost-effective alternative.

1.3 Engelhard’s Approach to Chlorine Dioxide Technology

Engelhard Aseptrol antimicrobial allows for the delivery of chlorine dioxide in a stable powder form. It is comprised of surfaces featuring selected sites with proprietary activators that react with chlorite salt contained in the powders to generate chlorine dioxide.

Aseptrol produces chlorine dioxide only when it comes into contact with water or when it is exposed to moisture in ambient air. Water or moisture provides the reaction bridge between the chlorite salt and the activator, allowing the generation of chlorine dioxide to proceed. When sealed in airtight containers, it can be stored and used when needed.
Aseptrol antimicrobial is available in loose powder, dissolvable tablets and sachets. For dry applications, Aseptrol can be used as a loose powder or sachet for a wide range of deodorizing and disinfectant applications. For solution applications, Aseptrol antimicrobial works in tablet or sachet form to begin releasing chlorine dioxide immediately after coming in contact with water and to continue releasing the biocide for up to four hours, depending on the formulation.

Aseptrol can be custom-formulated to deliver different levels of chlorine dioxide and to release the biocide at specific rates.

2. Overview of Engelhard Aseptrol ® Antimicrobial

2.a Delivery System Principles

Currently there are two varieties of Engelhard Aseptrol antimicrobial products:

• Controlled sustained release of chlorine dioxide gas (CSR)
• Solid precursors to chlorine dioxide solutions (SPS)

Figure A shows typical chlorine dioxide release profiles for the two main families of Aseptrol CSR type products:

Extended Release (CSR 1.xx)
- Low levels for 1 - 3 months

Rapid Release (CSR 7.xx)
- Spike followed by 1 - 20 day long tail

Controlling solid surface acidity is key to Aseptrol’s CSR products. Chlorine dioxide is formed by acidic disproportionation of the chlorite anion. Solid surface acids can drive this reaction. The rate depends upon the strength and concentration of acid sites with the duration controlled by the amount of NaClO₂ .

Engelhard’s core competencies in surface chemistry and materials science allow us to precisely synthesize the appropriate level of acidity needed to control chlorine dioxide formation from Aseptrol CSR materials.

In the case of solid precursors to chlorine dioxide solutions (SPS), Aseptrol SPS tablets exploit high-order reaction kinetics of chlorine dioxide synthesis.

Therefore, the key to rapidly converting the chlorite anion to chlorine dioxide is to perform the reaction at the highest possible concentration. Still, safe execution of such reactions requires precise control. For large-scale applications, a chemical generator may provide precise reaction control. However, for the multitude of applications where chemical generators are not feasible, Engelhard Aseptrol antimicrobial offers an elegant alternative.

The pore structure and formulation of an Aseptrol tablet is engineered to provide the superior environment in which to produce chlorine dioxide from chlorite anion. Upon immersing the tablet in water, water penetrates the pores and dissolves the solid reagents from the pore walls to produce an acidic solution that is saturated in chlorite anion. Under those conditions the chlorite is rapidly converted to chlorine dioxide, which diffuses from the tablet into the bulk solution, as depicted in Figure B.

FIGURE B

The reactions occur within the pores of the tablet and not in the bulk solution. It is only within the tablet’s engineered pores that the concentration of chlorite anion is high enough to convert to chlorine dioxide at a practically high rate.

In contrast to conventional methods that require acidification of the entire bulk solution to produce chlorine dioxide, bulk solution pH remains substantially unchanged with Aseptrol tablet use because the acidic reaction environment is substantially confined to the tablet’s pores. This advantage enables Aseptrol tablets to be used in applications where bulk solution acidification is undesirable, such as the production of alkaline detergent solutions of chlorine dioxide.

2.b. Efficacy Data

With 2.6 times the oxidizing capacity of chlorine, Aseptrol works over a broad pH range. Selective oxidation enables Aseptrol to seek out and destroy contaminants at their sources without leaving hazardous residues. Biocidal activity of Engelhard Aseptrol antimicrobial has been shown to be four-to-seven times more effective than chlorine at equivalent doses.

Aseptrol tablets have been tested using state-of-the-art procedures and have been shown to be effective sterilants and disinfectants. Aseptrol tablets are also effective against tuberculosis (TB), HIV-1 and several animal viruses, including Hantavirus. Aseptrol sachets are effective in controlling bacterial and fungal contamination including mold and mildew.

Engelhard has worked diligently with outside GLP (good laboratory practices) -- certified labs to ensure that all registrations are supported with actual data. Also it has partnered with major chemical and end use supply companies, in order to participate in field studies to document the efficacy of Aseptrol antimicrobial.

Distribution of chlorine dioxide through Engelhard Aseptrol antimicrobial also offers numerous advantages over sodium hypochlorite, glutaraldehyde, iodophors, quantenary ammonium compounds, and peracetic acid.

The figure below clearly identifies the benefits of chlorine dioxide over other conventional sanitizing agents .

2.c. Regulatory Approvals

Engelhard’s Aseptrol formulations are registered by the U.S. Environmental Protection Agency (EPA) as an antimicrobial for use in a wide variety of water purification and deodorization applications. Examples include: car- wash recycle water; litter box odor-control; shoe deodorization; emergency drinking water purification; controlling growth of bacteria in ice machines and water cooling towers; treating white water mold and pink slime in swimming pool plumbing systems; and, most recently, for sanitization applications for pathogen control.

See section 3 for additional details on applications.

2.d. Intellectual Property

Engelhard has taken an aggressive approach to securing intellectual property rights for Aseptrol antimicrobial, focusing primarily on obtaining composition of matter patents. Engelhard has secured composition of matter patents and also filed for and received use patents, such as a patent to use our Aseptrol sachets in ice machines.

2.e. Positioning in the Marketplace

Chlorine dioxide has been used in industry for more than 50 years. It is a well-known chemical to regulatory authorities and its safety impact is well understood.

Unlike chlorine, chlorine dioxide does not produce trihalomethanes (THMs) or dioxins; it is convenient to use and can be stored for long periods; it kills a wide range of bacteria, viruses and cysts; and it oxides/eliminates odor, making it an appealing alternative to many institutions, consumer product organizations and even households.

Engelhard has utilized its expertise in producing acidic minerals and zeolites with chlorine dioxide chemistry to develop Aseptrol, this unique antimicrobial technology that safely generates chlorine dioxide in small quantities and precise dosages.

Engelhard has entered into several alliances where the partner can provide application and marketing expertise with solid distribution networks. The alliance partners typically are chemical suppliers as well as end-use marketers. Engelhard will continue to leverage its expertise to acquire additional EPA registrations, provide toxicology and technical service, including the support of efficacy testing, formulation expertise, sub-registrations, and application development, in order to support of these alliances.

3. Applications of Engelhard Aseptrol ® Antimicrobial

Engelhard Aseptrol antimicrobial is one of the first commercial methods for long-term or residual control of microbial contamination.

Through its patented approach of chlorine dioxide distribution,” the ideal biocide,” Engelhard Aseptrol antimicrobial offers many significant benefits, such as:

• Works against a wide variety of bacteria, yeasts, viruses, fungi, protozoa, spores, molds, mildews, and other microbes.
• Exhibits rapid kill of target organisms, often in just seconds.
• Effective at low concentration and over a wide pH range.
• Biodegrades in the environment.
• Does not generate harmful by-products.

3.a. Current Applications

Highly versatile, Engelhard Aseptrol antimicrobial performs a wide range of functions – including odor control, disinfecting, and sanitizing – in water treatment and purification, consumer products, healthcare, and many other applications.

For example, Aseptrol is featured in two new water treatment applications in order to:

• Prevent and control algae bloom in non-chlorine swimming pools.
• Eliminate microbial buildup in resin beds of home water softeners.

Other applications include:

• Water purification—Demonstrated effectiveness against cryptosporidium. Chlorine can produce THMs and iodine pills often leave a bad taste. No other current waterpurification solution has demonstrated such effectiveness against cryptosporidium.
  Other markets include:

  • Cooling tower water
  • Potable or emergency drinking water
  • Car-wash recycle water
  • Food processing
  • Recreational water
• Odor control—Deodorizing or killing odor-causing bacteria via Aseptrol sachets or powders for:
  • Carpeting
  • Shoes
  • Ice machines
  • Soft surfaces contaminated with bacteria and mold
• Odor control in confined spaces such as:
  • Boats
  • RVs
  • Diaper pails
  • Garbage receptacles
• Pathogen Control applications—animal rearing and confinement facilities, kennels and cages. Aseptrol is EPA-registered to work against:

  • Canine parvovirus
  • Mouse hepatitis virus (MHV)
  • Sialodacryoadentitis virus (SDAV)
  • Murine parainfluenza virus type 1 ( Sendai)
  • Mouse parvovirus type 1 (MPV-1)
  • Minute virus of mice (MVM)
  • Tuberculosis
• Military / Security applications:
  • Disinfect hard surfaces
  • Purify emergency drinking water
  • Deodorize and kill odor-causing bacteria in soft surfaces and confined spaces

3.b. Potential Applications

Engelhard is conducting lab tests to determine the chlorine dioxide concentrations needed to kill the Norwalk Virus, suspected of sickening people on cruise ships; to kill Hoof and Mouth disease, which has plagued farmers and their livestock around the world; and to kill Newcastle virus, a contagious and fatal viral disease affecting poultry.

Engelhard is working on methods to extrude its Aseptrol formulations into film. Such extrusions could then be used or incorporated into packages that may extend the life of fruits and vegetables, or to inhibit mold growth. Myriad potential applications in this area exist, and can be found in almost any market where storage, shipping and shelf life can be compromised, due to mold or mildew or where bacterial growth is present.

3.c. Alternate Scenarios

Alternative uses typically involve the formulation of Aseptrol in combination with other technologies. Engelhard researchers have developed tablets that not only generate chlorine dioxide but also can conveniently deliver surfactants, dyes and complementary biocides. These formulations can also be formulated to release their chlorine dioxide at the existing solution pH, or to deliver excess acid and generate acidic solutions, depending upon the users preferences.

Target market applications include tablets for toilet treatment, dental line cleaners and dental water purifiers, teat dip treatment and clean in place markets for food and non-food facilities. Sachets, formulated with other adsorbents can offer the “one-two punch” of not only killing odorcausing bacteria, but in adsorbing odors against which chlorine dioxide has not been efficacious.

3.d. Future Vision

Certain biocides are facing increasing scrutiny as their safety profiles are evaluated. Chlorine dioxide may be viable alternatives for these biocides. For example:

• Halogenated biocides (i.e.- chlorine, hypochlorite) have been shown to form THMs, known cancer-causing compounds.
• Other biocides, such as phenolics, glutaldehyde or quats, which have toxicity and performance issues and are being used less frequently.

Although there has been a trend to move away from biocides with poor eco-toxicity profiles, chlorine dioxide, due to its delivery limitations, was never considered a viable option. Now that Aseptrol antimicrobial is available with a user-friendly delivery profile, chlorine dioxide is likely to be reviewed and reconsidered as an alternative to these biocides.

4. Summary

Engelhard Aseptrol antimicrobial is guided by our ingenuity and fostered by our drive as a technology-based and market-driven enterprise.

Aseptrol offers numerous advantages including:

• More effective decontamination—works against a wide variety of bacteria, yeasts, viruses, fungi, protozoa, spores, molds, mildews and other microbes.
• Shorter contact time—rapid kill of target organisms, often in seconds.
• Minimal corrosion.
• Low toxicity.
• Biodegradability in the environment.
• Does not generate harmful byproducts.
• Unique in its ability to deliver mg to kg quantities of chlorine dioxide without costly training or equipment.
• Effectively performs in low concentrations over a wide range of pH levels.

As a pioneering technology embedded within a wide variety of diverse end-use applications, Engelhard Aseptrol antimicrobial is expected to play a significant role in improving the quality of life for generations to come.

5. About the Author

Michael Cochran is the Business Development Manager for Aseptrol antimicrobial at Engelhard Corporation, a surface and materials science company that develops technologies to improve customers’ products and processes.

Joining Engelhard in 1997, he has worked in the chemical industry for nearly 20 years. Mr. Cochran has held various positions in sales, regional management, product management and new business development. He sits on the American Chemistry Council’s Sodium Chlorite Panel. He holds a Bachelor of Science degree in management from Rutgers University and an MBA in chemical marketing from Fairleigh Dickinson University.

Michael can be reached at michael.cochran@engelhard.com . For additional information about Engelhard Aseptrol antimicrobial, visit www.engelhard.com/aseptrol .