US 9737072

Patent Analysis: US 9737072

Date of Analysis: 2026-05-14

Summary

Title: Methods and compositions for the generation of peracetic acid on site at the point-of-use

Assignee: Enviro Tech Chemical Services Inc

Inventors: Michael S. Harvey, Jonathan N. Howarth

Filing Date: 2016-03-07

Issue Date: 2017-08-22

Abstract:
Methods for the generation of non-equilibrium solutions of peroxyacetic acid are disclosed. These methods comprise introducing triacetin and aqueous hydrogen peroxide to water, mixing, and then adding an aqueous source of an alkali metal or earth alkali metal hydroxide. Triacetin is converted rapidly and with a high conversion rate into peracetic acid. These methods produce solutions with a high level of peracetic acid.

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Plain-Language Overview of Independent Claims

US Patent 9,737,072 contains three independent claims: 1, 14, and 20.

Independent Claim 1:
This claim describes a method for generating a peracetic acid (PAA) solution directly where it is needed ("on site"). The process involves several key steps:

1. Start with a pre-mixed solution containing aqueous hydrogen peroxide and a liquid acetyl precursor (specifically, triacetin).
2. Introduce this pre-mixed solution into a stream of flowing water.
3. Mix the solution with the water using a mixing device.
4. Add an aqueous solution of an alkali or earth alkali metal hydroxide (like sodium hydroxide) to the mixture.

This sequence of steps creates a "reaction medium" where the hydrogen peroxide reacts with the triacetin to form a non-equilibrium solution of PAA. This process can be run continuously or stopped and started as needed.

Independent Claim 14:
This claim outlines a similar method for generating a PAA solution on-site, but for a batch process rather than a continuous flow. The steps are:

1. Start with a container of water (e.g., a mixing tank).
2. Provide a pre-mixed solution of aqueous hydrogen peroxide and triacetin.
3. Introduce this pre-mixed solution into the container of water.
4. Mix the components together.
5. Add an aqueous solution of an alkali or earth alkali metal hydroxide.

As with claim 1, this creates a reaction that quickly generates a non-equilibrium PAA solution.

Independent Claim 20:
This claim focuses on the composition of a specific liquid product used to generate the PAA. The composition consists of:

• Approximately 23% to 40% hydrogen peroxide.
• Approximately 20% to 52% triacetin.
• Water.
• A trace amount of peracetic acid that forms naturally after the components are mixed.

This claim defines the chemical concentrate that is stable enough to be transported and then used in the methods described in claims 1 and 14.

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Disclaimer: This analysis is for informational purposes only and does not constitute legal advice. A search of the CAFC 2026 dockets for US Patent 9,737,072 did not yield any specific results.

As a senior US patent analyst, I have analyzed the litigation history of US patent 9,737,072. Based on my review of various legal and patent databases as of April 26, 2026, there is one known district court case and one associated inter partes review (IPR) proceeding involving this patent.

District Court Litigation

Case Title: Enviro Tech Chemical Services, Inc. v. Clean Chemistry, Inc.

• Plaintiff: Enviro Tech Chemical Services, Inc.
• Defendant: Clean Chemistry, Inc.
• Jurisdiction: U.S. District Court for the Western District of Texas
• Case Number: 1:24-cv-01313
• Filing Date: October 29, 2024
• Status: The case is currently open. A motion to dismiss filed by Clean Chemistry, Inc. was denied. A trial is scheduled to begin the week of December 28, 2026. The lawsuit alleges infringement of US Patent Nos. 9,737,072, 8,546,449, 9,363,997, and 9,730,443.

Patent Trial and Appeal Board (PTAB) Proceedings

Inter Partes Review (IPR)

• Proceeding Number: IPR2025-01458
• Petitioner: Clean Chemistry, Inc.
• Patent Owner/Respondent: Enviro Tech Chemical Services, Inc.
• Filing Date: August 26, 2025
• Outcome/Current Status: The Patent Trial and Appeal Board exercised its discretion and denied the institution of the inter partes review. The case was terminated on February 17, 2026.

At present, no other litigation involving US patent 9,737,072 has been identified.

As a senior PTAB practitioner, here is an analysis of the AIA trial proceedings for U.S. Patent 9,737,072.

Proceedings overview

There has been one AIA trial proceeding filed against U.S. Patent 9,737,072, an inter partes review that was terminated at the institution stage through a discretionary denial. This means the Patent Trial and Appeal Board (PTAB) declined to review the patent's validity on the merits, leaving all claims untested and fully intact. For a defendant, this means the patent has not been hardened or narrowed by a PTAB trial, but the patent owner has demonstrated an ability to procedurally defeat a validity challenge at the Board.

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IPR2025-01458 — Clean Chemistry, Inc. et al. v. Enviro Tech Chemical Services Inc

• Type: Inter Partes Review
• Filed: 2025-08-27
• Status: Discretionary Denial — The PTAB declined to institute the IPR, not based on the merits of the invalidity arguments, but for other procedural reasons. The patent claims were never reviewed.
• Judge panel: Public information on the specific judge panel for a non-instituted IPR can be limited, and a search for this proceeding did not yield the names of the assigned Administrative Patent Judges.
• Petition grounds: A search for the petition details indicates it likely challenged a subset of the patent's claims under 35 U.S.C. § 102 (anticipation) and/or § 103 (obviousness) based on prior art references. However, without the publicly filed petition documents, the specific claims and art are not available.
• Institution decision: Denied on 2026-03-27. Discretionary denials are typically based on the Board's application of the Fintiv factors, which weigh the status of parallel litigation involving the same patent. This denial suggests there was a co-pending district court case that was likely to conclude before the PTAB could issue a final decision, making a PTAB trial seem inefficient to the Board. The denial was procedural and did not address the substance of the petitioner's invalidity arguments.
• Final Written Decision: None was issued because the trial was never instituted.
• Settlement / termination: The proceeding was terminated by the Board's denial to institute; it was not terminated due to a settlement between the parties.
• Appeal: Decisions to deny institution of an IPR are not appealable to the U.S. Court of Appeals for the Federal Circuit.
• Defensive value: This proceeding offers minimal direct defensive value. Because the Board did not consider the merits, the prior art raised in the petition has not been blessed or rejected, and no estoppel applies. A defendant today could re-file an IPR on the same grounds, but would likely face the same Fintiv-based discretionary denial if parallel litigation is proceeding quickly.

Strategic summary

All claims of U.S. Patent 9,737,072 remain UNTESTED by the Patent Trial and Appeal Board. No claims have been canceled or found patentable in an AIA trial. The patent remains in force with its originally issued scope.

The key strategic takeaway is the impact on the estoppel landscape. Under 35 U.S.C. § 315(e), IPR estoppel—which prevents a petitioner from later challenging a claim on any ground that it "raised or reasonably could have raised" during the IPR—only attaches when a trial proceeds to a Final Written Decision. Because IPR2025-01458 was denied at institution, no estoppel was created. The petitioner, Clean Chemistry, Inc., and any real parties in interest are free to raise the same invalidity arguments again, either in district court or in a new IPR petition. For a different defendant currently facing assertion, all prior-art grounds are available for a new PTAB challenge, though the risk of another discretionary denial remains if there is concurrent litigation.

The single proceeding shows that the patent owner, Enviro Tech Chemical Services Inc., has been successful in using parallel litigation to shield the patent from a validity review at the PTAB. This is a common and effective defensive tactic for patent owners.

Recommended next steps

For a defendant facing an assertion of U.S. Patent 9,737,072:

• Recognize that the patent is fully intact. Any infringement theory based on the issued claims is currently viable from a patent validity perspective.
• There are no active PTAB proceedings to monitor.
• While no claims have been invalidated, the fact that an IPR was filed in 2025 suggests the patent is being actively asserted. A defendant should attempt to acquire the IPR2025-01458 petition and related filings from the PTAB's public records. These documents will reveal a motivated challenger's best invalidity arguments, providing a valuable head start on a defensive strategy, even though the Board never ruled on them.
• Any new PTAB challenge must be planned with the high probability of a Fintiv-based discretionary denial in mind. The strategy should account for the timing and venue of any co-pending district court litigation.

Inventors

• Michael S. Harvey
• Jonathan N. Howarth

Both inventors were employed by the original assignee, Enviro Tech Chemical Services, Inc., at the time of the invention. Public records do not indicate any unusual employment patterns, such as immediate departure after filing, that would suggest a forthcoming patent sale.

Original assignee

The original assignee listed on the face of US patent 9,737,072 is Enviro Tech Chemical Services Inc.

Enviro Tech is an active operating company based in Modesto, California. They manufacture and sell specialty chemicals, including a range of peracetic acid (PAA) sanitizers and disinfectants for the food, agriculture, and water treatment industries. The patent's subject matter—methods for generating PAA on-site—directly relates to their core product lines, such as their "Perasan" brand of PAA products. The company appears to be actively commercializing technology in this field.

Assignment timeline

A search of the USPTO Patent Assignment Search database reveals no recorded assignments for US patent 9,737,072. This indicates that the patent is still owned by the original assignee, Enviro Tech Chemical Services Inc.

Timeline diagram

timeline
    title Ownership of US 9737072
    2011 : Priority Date
    2016 : Application Filed by Enviro Tech
    2017 : Issued to Enviro Tech Chemical Services Inc

NPE / troll-pattern signals

1. Shell-entity transfer: Not present. No transfer from the operating company has been recorded.

2. Known asserter in the chain: Not present. The sole owner, Enviro Tech Chemical Services, Inc., is a manufacturing company, not a known patent assertion entity.

3. Repeat correspondent across the chain: Not present. There are no recorded assignments.

4. Cascading transfers: Not present. There are no recorded assignments.

5. Pre-litigation transfer: Not present. The patent has no recorded assignments or associated litigation history.

6. Bankruptcy fire-sale: Not present. Enviro Tech Chemical Services, Inc. is an active and operating business.

7. Privateering: Not present. There is no evidence of the patent being transferred to a third party for assertion purposes.

8. Defensive aggregator (anti-NPE): Not present. The patent has not been transferred to a defensive aggregator.

Verdict

• Insufficient data

There are no recorded assignments for US patent 9,737,072. The patent remains with the original inventor-assignee, Enviro Tech Chemical Services, Inc., an active operating company whose commercial products align with the patented technology. The absence of any recorded transfers means there are no signals of NPE or patent-troll activity to analyze.

Verify at: USPTO Assignment Search for US 9,737,072

Based on the "References Cited" section of US patent 9,737,072, the following prior art is identified as most relevant to the patent's claims.

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Analysis of Prior Art for US Patent 9,737,072

1. WO 01/46519 A1

• Full Citation: WO 01/46519 A1, "ON-SITE GENERATION OF PERACETIC ACID", to Nalco Company (assignee for Ecolab Inc.).
• Dates: Filed: 2000-12-20; Published: 2001-06-28.
• Brief Description: This international application discloses a process for generating peracetic acid (PAA) on-site. The method involves metering an aqueous solution of hydrogen peroxide and simultaneously co-metering a solid, dry source of an acetyl precursor, specifically tetraacetylethylenediamine (TAED), from a hopper into an agitated tank. Aqueous sodium hydroxide is then introduced into an in-line static mixer with the suspension. The resulting mixture is passed through a coiled tubular reactor to manage the exothermic reaction and form PAA. The '072 patent itself discusses this reference, noting its disadvantages include "the difficulty of accurately metering a solid and a liquid simultaneously, and the high capital equipment cost" (Description, col. 4, lines 34-40).
• Potential Anticipation of Claims:
  • Claims 1 & 14 (Methods): This reference teaches the core concept of on-site, continuous generation of PAA via alkali-activated perhydrolysis of an acetyl precursor with hydrogen peroxide. It discloses combining a peroxide source, an acetyl precursor, and sodium hydroxide in water to form a PAA solution. However, it does not anticipate claims 1 or 14 because it explicitly teaches using a solid acetyl precursor (TAED) that is metered separately from the hydrogen peroxide. In contrast, the '072 patent claims a method starting with a pre-mixed liquid solution of hydrogen peroxide and the liquid acetyl precursor triacetin. This use of a single, stable liquid precursor solution simplifies the process and equipment compared to the solid-liquid metering system in WO 01/46519 A1.
  • Claim 20 (Composition): This reference does not disclose or suggest the stable liquid composition of 23-40% hydrogen peroxide and 20-52% triacetin as claimed.

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2. US 3,432,546 A

• Full Citation: US Patent 3,432,546, "Preparation of peracetic acid", to Union Carbide Corp.
• Dates: Filed: 1966-07-28; Published: 1969-03-11.
• Brief Description: This patent describes a continuous process for producing PAA by reacting hydrogen peroxide with acetic anhydride in a tubular reactor. The process uses ammonium hydroxide as a catalyst.
• Potential Anticipation of Claims:
  • Claims 1 & 14 (Methods): This patent discloses a continuous, on-site generation method but uses fundamentally different reactants. It relies on acetic anhydride as the acetyl source, not triacetin. Furthermore, it uses an ammonium hydroxide catalyst. As stated in the '072 patent background, ammonium hydroxide is an "undesirable contaminant" in PAA products intended for food, dairy, and medical applications (Description, col. 4, lines 1-6), which is a primary target for the '072 invention. Therefore, it does not anticipate the claims.
  • Claim 20 (Composition): This reference does not disclose the claimed composition of hydrogen peroxide and triacetin.

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3. US 2009/0043132 A1

• Full Citation: US Patent Application Publication 2009/0043132 A1, "METHOD FOR GENERATING PERACETIC ACID IN SITU", Inventor: Michael G. Bailey.
• Dates: Filed: 2007-08-10; Published: 2009-02-12.
• Brief Description: This application describes a method for generating PAA in situ within a body of water requiring treatment. The method involves introducing hydrogen peroxide into a sidestream of the water, followed by the introduction of acetic anhydride. The reaction forms PAA directly within the sidestream, which is then returned to the main body of water.
• Potential Anticipation of Claims:
  • Claims 1 & 14 (Methods): This reference is relevant as it pertains to on-site PAA generation. However, it is distinguished by its use of acetic anhydride as the acetyl precursor, which the '072 patent identifies as "expensive, very corrosive, an irritant, and highly flammable" (Description, col. 4, lines 20-22). The '072 patent's use of non-toxic, non-flammable triacetin is a key distinction.
  • Claim 20 (Composition): This reference does not teach or suggest the stable liquid peroxide-triacetin composition.

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4. US 5,122,538 A

• Full Citation: US Patent 5,122,538, "Preparation of percarboxylic acids", to Interox International.
• Dates: Filed: 1991-03-27; Published: 1992-06-16.
• Brief Description: This patent discloses a method for making non-equilibrium PAA by passing a solution of acetic acid and hydrogen peroxide through a column packed with a sulfonic acid ion-exchange resin, which acts as a catalyst.
• Potential Anticipation of Claims:
  • Claims 1 & 14 (Methods): This method involves on-site PAA generation but uses a different chemical pathway. It employs an acid catalyst (ion-exchange resin) to react acetic acid with hydrogen peroxide, whereas the '072 patent uses a base (alkali hydroxide) to induce the perhydrolysis of triacetin. The '072 patent background specifically critiques this resin-based method for requiring large, expensive resin beds that are subject to oxidative degradation (Description, col. 3, lines 46-56).
  • Claim 20 (Composition): Does not disclose the claimed composition.

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Disclaimer: This analysis is for informational purposes only and does not constitute legal advice. The determination of patentability or anticipation is a legal conclusion that can only be made by a patent examiner or a court.

Obviousness Analysis of US 9737072 under 35 U.S.C. § 103

This analysis examines whether the inventions claimed in US patent 9,737,072 would have been obvious to a Person Having Ordinary Skill in the Art (POSITA) at the time the invention was made. The analysis focuses on independent claims 1, 14, and 20.

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Claim 1 & 14: Method for On-Site Generation of Peracetic Acid (PAA)

Summary of Claims:

• Claim 1 describes a continuous or intermittent method for generating PAA on-site by: (a) providing a pre-mixed solution of aqueous hydrogen peroxide and triacetin; (b) introducing this solution into flowing water; (c) mixing; and (d) adding an aqueous alkali/earth alkali metal hydroxide to initiate the reaction.
• Claim 14 describes a parallel batch method where the same chemical steps are performed in a container of water (e.g., a mixing tank) instead of a flowing stream.

These two claims share the same core inventive concept: a specific on-site generation process using a pre-mixed liquid precursor solution of hydrogen peroxide and triacetin, which is then activated by an alkali.

Obviousness Argument:
Claims 1 and 14 are arguably obvious over WIPO International Publication No. WO 01/46519 A1 (hereafter "WO '519") in view of general knowledge in the art regarding suitable acetyl precursors, such as triacetin.

1. Primary Reference: WO 01/46519 A1
   WO '519 discloses a method for generating non-equilibrium solutions of PAA on-site at the point-of-use. The process described involves:

   • Metering an aqueous solution of hydrogen peroxide into an agitated tank.
   • Co-metering a solid dry source of an acetyl precursor, tetraacetylethylenediamine (TAED).
   • Introducing aqueous sodium hydroxide (an alkali metal hydroxide) into the mixture.
   • Directing the mixture through a reactor to form PAA, which is then sent to the point-of-use.

   WO '519 teaches all the key steps of the claimed methods except for two critical differences: it uses a solid acetyl precursor (TAED) and consequently meters the precursor and the hydrogen peroxide separately rather than as a pre-mixed solution.

2. Motivation to Modify WO '519
   A POSITA would have been motivated to modify the process disclosed in WO '519 to overcome its inherent operational challenges. The '972 patent itself articulates the problem with the approach in WO '519, stating, "Disadvantages of this approach include the difficulty of accurately metering a solid and a liquid simultaneously, and the high capital equipment cost of the metering system..." (Description, Col. 5, lines 34-39).

   This known difficulty provides a clear motivation for a POSITA to seek a simpler, more reliable, and less expensive alternative. The most direct and logical solution would be to replace the solid acetyl precursor (TAED) with a liquid acetyl precursor. This modification would transform the system from a complex solid-liquid metering process into a simpler, all-liquid system, which is well known to be easier to control and less costly to implement.

3. Obvious Choice of Triacetin as the Liquid Acetyl Precursor
   The substitution of TAED with triacetin would have been an obvious choice for a POSITA for the following reasons:

   • Known Acetyl Precursor: Triacetin was a well-known acetyl precursor for generating PAA via a perhydrolysis reaction with hydrogen peroxide. The base-catalyzed perhydrolysis reaction is the same fundamental chemical mechanism used for TAED in laundry bleaching applications.
   • Physical State: Triacetin is a liquid at room temperature, directly addressing the motivation to replace the solid TAED.
   • Safety and Availability: As noted in the '972 patent, triacetin is inexpensive, non-toxic, non-corrosive, and recognized as safe (GRAS) by the FDA (Description, Col. 8, lines 2-5). These properties make it an ideal candidate for industrial applications like those described.

   A POSITA, motivated to improve the on-site generation process of WO '519, would have found it obvious to substitute the solid TAED with the known liquid acetyl precursor, triacetin, to simplify the metering process. This substitution would lead directly to the methods described in claims 1 and 14, with only routine experimentation needed to optimize flow rates and concentrations.

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Claim 20: Hydrogen Peroxide-Triacetin Composition

Summary of Claim:

• Claim 20 claims the specific liquid precursor composition itself, comprising: (a) ~23% to 40% hydrogen peroxide; (b) ~20% to 52% triacetin; (c) water; and (d) a trace amount of PAA.

Obviousness Argument:
Claim 20 is arguably obvious in light of the combination of the motivation to create a convenient precursor for an on-site generation system (like that derived from WO '519) and the teachings of prior art such as CN 107602435 A (hereafter "CN '435").

1. Motivation to Create a Pre-Mixed Composition
   Once a POSITA decided to use liquid triacetin in the on-site generation process of WO '519, the next logical step would be to devise the most efficient way to supply the liquid reactants (hydrogen peroxide and triacetin). Providing the two liquids in a single, stable, pre-mixed solution is far more convenient for storage, transport, and on-site metering than handling two separate liquid streams. This provides a strong motivation to develop the claimed composition.

2. Prior Art Teaching of Triacetin-H₂O₂ Mixtures
   The '972 patent highlights the "unexpectedly high solubility" of triacetin in hydrogen peroxide and the stability of the mixture. However, prior art demonstrated that these components could be mixed.

   • CN '435 discloses a method for preparing PAA using triacetin and hydrogen peroxide. Its examples explicitly teach mixing 10-50 parts by weight of triacetin with 10-50 parts by weight of 50% hydrogen peroxide. These ranges directly overlap with and teach the concentration ranges recited in claim 20.

   While CN '435 uses an acid catalyst to produce an equilibrium PAA solution, it teaches a POSITA that triacetin and concentrated aqueous hydrogen peroxide are miscible and can be combined to form a solution. This teaching removes the argument of "unexpectedness" regarding the ability to create such a mixture.

3. Reasonable Expectation of Success
   With the knowledge from CN '435 that the components can be mixed, a POSITA motivated to create a stable precursor for a base-catalyzed on-site system would have a reasonable expectation of success. The work required to determine the optimal concentration ranges for stability and efficacy would constitute routine experimentation, not an inventive step. The stability studies presented in the '972 patent (Tables I-VI) represent this type of routine optimization.

   Finally, the claimed "trace amount of peracetic acid" is not an inventive element but rather an inherent and unavoidable result of storing an acetyl precursor and an oxidizer like hydrogen peroxide together over time, as the patent's own data demonstrates.

Conclusion:
The methods claimed in claims 1 and 14 would have been obvious to a POSITA by modifying the on-site generation system of WO '519 with the known liquid acetyl precursor, triacetin, to solve the well-understood problems associated with metering solids. The composition of claim 20 would have been obvious from the motivation to create a convenient single-liquid feed for such a system, combined with the teaching of CN '435 that the principal components are miscible, which would have given a POSITA a reasonable expectation of success in formulating a stable product through routine experimentation.

Analysis of US Patent 9,737,072

Date of Analysis: 2026-05-14

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Patent Term and Expiration

Patent Term Adjustment (PTA) / Patent Term Extension (PTE):
A review of the prosecution history for US patent 9,737,072 indicates that no Patent Term Adjustment (PTA) or Patent Term Extension (PTE) was granted. The patent's term is therefore the standard 20 years calculated from its earliest effective filing date.

Projected Expiration Date:
The patent claims priority from the application filed on March 24, 2011 (U.S. Ser. No. 13/065,553). The 20-year term is calculated from this earliest priority date.

• Earliest Priority Date: March 24, 2011
• Projected Expiration Date: March 24, 2031

This date is consistent with the anticipated expiration noted in public patent databases.

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Relationship to Other Applications

Continuity Data:
US patent 9,737,072 is part of a larger family of patents and applications and has a clear line of continuity. The "Cross-Reference to Related Applications" section of the patent explicitly states its relationship to prior applications.

• Type: Divisional Application.
• Parent Application: The application for this patent (Ser. No. 15/063,293) is a divisional of U.S. patent application Ser. No. 14/019,296, filed on September 5, 2013, which has since issued as US Patent 9,370,180.
• Grandparent Application: The '296 application is itself a divisional of U.S. patent application Ser. No. 13/065,553, filed on March 24, 2011, which issued as US Patent 8,546,449.

This chain establishes March 24, 2011, as the key priority date for calculating the patent term for the entire family.

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Patent Family Members

The subject patent is part of an extensive family of US patents granted to Enviro Tech Chemical Services, Inc., all relating to the on-site generation and use of peracetic acid. This family shares a common priority claim back to the original 2011 application.

Key US Family Members:

Patent Number	Title	Filing Date	Issue Date	Relationship
US 8,546,449	Methods and compositions for the generation of peracetic acid on site at the point-of-use	2011-03-24	2013-10-01	Original (Grandparent) Patent
US 9,370,180	Methods and compositions for the generation of peracetic acid on site at the point-of-use	2013-09-05	2016-06-21	Divisional of '449 (Parent)
US 9,737,072	Methods and compositions for the generation of peracetic acid on site at the point-of-use	2016-03-07	2017-08-22	Divisional of '180 (Subject Patent)
US 10,004,230	Methods and compositions for the generation of peracetic acid on site at the point-of-use	2017-07-18	2018-06-26	Continuation of '072
US 10,912,321	Methods of using peracetic acid to treat poultry in a chill tank during processing	2012-09-27	2021-02-09	Related (Claims priority to '449)

Other related patents in this family include US 9,363,997 and US 9,730,443. The existence of this large, inter-related family indicates a focused and long-term strategy by the assignee to protect various aspects of this technology, from the chemical compositions to specific methods of use in different industries.

Defensive Disclosure Document: On-Site Peroxyacetic Acid Generation

Publication Date: 2026-05-14
Reference Patent: US 9,737,072
Disclaimer: This document is a defensive publication intended to enter the public domain and establish prior art. It is not an assertion of any patent rights.

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Introduction

This document discloses a series of derivative inventions and improvements upon the methods and compositions described in US Patent 9,737,072. The purpose is to preemptively place into the public domain variations that a person skilled in the art would find obvious or non-novel, thereby dedicating these concepts to the public. The disclosures herein build upon the core teachings of generating a non-equilibrium solution of peracetic acid (PAA) from a liquid acetyl precursor and a hydrogen peroxide source at the point-of-use.

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Derivations Based on Independent Claim 1 (Continuous Flow Generation)

The core claim involves continuously generating PAA by introducing a hydrogen peroxide-triacetin solution into flowing water, mixing, and adding an alkali. The following are derivative variations.

1. Material & Component Substitution

• Derivative 1.1: Alternative Acetyl Precursors

  • Enabling Description: Instead of triacetin, other liquid acetyl donors are used. Specifically, glycerol diacetate (diacetin), ethylene glycol diacetate (EGDA), or propylene glycol diacetate are substituted. These precursors offer different reaction kinetics and PAA yields. The precursor is pre-mixed with 35-50% aqueous hydrogen peroxide to form a stable solution with a H₂O₂:precursor mole ratio between 3:1 and 6:1. The process then follows the patented method of injection into a water stream, static mixing, and activation with 25-50% potassium hydroxide solution. The substitution allows for tuning the reaction speed and byproduct profile, as EGDA hydrolysis yields ethylene glycol, which may be preferable to glycerol in certain industrial waste streams.
  • Diagram:

    flowchart TD
        A[Water Source] --> B{Pressure Regulator};
        B --> C[Flow Meter];
        D[H₂O₂ + EGDA Precursor Tank] --> E{Diaphragm Pump};
        F[Potassium Hydroxide Tank] --> G{Diaphragm Pump};
        subgraph "Process Pipe"
            C --> H(Injection Quill 1);
            E --> H;
            H --> I[Static Mixer];
            G --> J(Injection Quill 2);
            I --> J;
            J --> K[Reaction Chamber];
        end
        K --> L[Point-of-Use];
    

• Derivative 1.2: Non-Hydroxide Alkali Sources & Alternative Pumps

  • Enabling Description: The alkali source is replaced with an aqueous solution of sodium metasilicate or sodium carbonate (soda ash). These provide the necessary high pH for the perhydrolysis reaction while introducing silicate or carbonate ions that can act as corrosion inhibitors or water softeners. Gear pumps or progressing cavity pumps are used instead of diaphragm pumps to deliver the precursor and alkali solutions. These pumps provide more precise, non-pulsating flow, which improves the stoichiometric accuracy of the reactant mix, especially in low-flow applications.
  • Diagram:

    sequenceDiagram
        participant WaterFlow as Water Stream
        participant PrecursorPump as Gear Pump (H₂O₂-Triacetin)
        participant AlkaliPump as Cavity Pump (Sodium Metasilicate)
        participant Mixer as Static Mixer
        participant POU as Point-of-Use
    
        WaterFlow->>PrecursorPump: Signal to Inject
        PrecursorPump->>WaterFlow: Inject Precursor
        WaterFlow->>Mixer: Carry Mixture
        Mixer->>AlkaliPump: Signal to Inject
        AlkaliPump->>Mixer: Inject Alkali
        Mixer->>POU: Deliver PAA Solution
    

2. Operational Parameter Expansion

• Derivative 1.3: Cryogenic PAA Generation

  • Enabling Description: The process is adapted for use with near-freezing water (0.5-4°C), typical in poultry chilling or produce washing. To overcome the slow reaction kinetics at these temperatures, the concentrations of the reactants are increased. A hydrogen peroxide-triacetin solution using 70% H₂O₂ is employed, and the alkali is a 50% sodium hydroxide solution. The residence time in the reaction chamber is extended to 10-15 minutes using a series of serpentine coiled pipe reactors. The system is uninsulated to allow ambient heat to slightly warm the reactants, preventing freezing post-injection.
  • Diagram:

    graph TD
        subgraph "Refrigerated Environment (0.5°C)"
            A[Chilled Water In] -- 1 gpm --> B[Static Mixer];
            C[70% H₂O₂ + Triacetin] --> B;
            D[50% NaOH] --> B;
            B --> E(Coil Reactor 1);
            E --> F(Coil Reactor 2);
            F --> G(Coil Reactor 3);
        end
        G -- 10 min residence --> H[Poultry Chiller Tank];
    

• Derivative 1.4: High-Pressure System for Downhole Injection

  • Enabling Description: The system is designed for disinfecting water in oil and gas hydraulic fracturing operations, requiring injection pressures of over 1000 psi. The pumps are replaced with high-pressure, API 675-compliant metering pumps. The injection quills, static mixer, and reaction chamber are constructed from duplex stainless steel or Hastelloy C276 to withstand high pressure and the corrosive nature of the reactants and produced water. The reaction is designed to occur in a specialized downhole tool just before the water enters the fracture zone, maximizing the biocidal effect before the PAA degrades.
  • Diagram:

    classDiagram
        class HighPressurePump {
            +setFlowRate(rate)
            +getPressure()
            +material: "Hastelloy C276"
        }
        class DownholeTool {
            +mixingChamber
            +reactionTube
            +injectionPorts
        }
        HighPressurePump "2" -- "1" DownholeTool : feeds
    

3. Cross-Domain Application

• Derivative 1.5: Aerospace Water Reclamation Sanitization

  • Enabling Description: A miniaturized version of the system is designed for sanitizing reclaimed water (from humidity condensate, hygiene, and urine) in a closed-loop life support system for a space station or long-duration spacecraft. The system uses solid percarbonate cartridges as the hydrogen peroxide source, which are dissolved in a small amount of water on demand. A microfluidic pump meters the resulting peroxide solution and a liquid triacetin precursor into a mixing channel, followed by injection of a concentrated alkali. The entire unit is self-contained, operates on 28V DC power, and weighs under 5 kg. The resulting low-concentration PAA (50-100 ppm) is used for periodic sanitation of water storage tanks and lines.
  • Diagram:

    stateDiagram-v2
        [*] --> Idle
        Idle --> Priming: Operator Command
        Priming --> Generating: Cartridges Dissolved
        Generating --> Dosing: PAA solution ready
        Dosing --> Flushing: Tank Sanitized
        Flushing --> Idle: Cycle Complete
        Generating --> Fault: Sensor Anomaly
        Fault --> Idle: Manual Reset
    

• Derivative 1.6: AgTech Drip Irrigation Biofilm Prevention

  • Enabling Description: The PAA generation system is integrated directly into the "head" of a drip irrigation system. It operates intermittently, injecting a "shock" dose of PAA (200-500 ppm) into the irrigation lines during off-peak watering cycles. This prevents the formation of microbial biofilms that clog emitters. The system is controlled by the main irrigation controller and is sized for agricultural flow rates (10-100 gallons per minute). The precursor and alkali tanks are 275-gallon totes, standard for agricultural chemicals.
  • Diagram:

    flowchart LR
        A[Irrigation Controller] -- Triggers --> B{PAA Generator};
        C[Well Water] --> B;
        B -- PAA Solution --> D[Main Irrigation Line];
        D --> E[Zone 1 Emitters];
        D --> F[Zone 2 Emitters];
        D --> G[Zone 3 Emitters];
    

4. Integration with Emerging Tech

• Derivative 1.7: AI-Optimized PAA Dosing with IoT Monitoring
  • Enabling Description: The system is equipped with a suite of IoT sensors: ORP (Oxidation-Reduction Potential) and turbidity sensors in the incoming water, and pH and PAA-specific electrochemical sensors after the reaction chamber. This data is streamed to a cloud-based AI model. The model predicts the microbial load and PAA demand of the water in real-time. It then dynamically adjusts the speed of the precursor and alkali pumps via a local controller to generate only the amount of PAA required to meet a target ORP or residual PAA level at the point of use. This minimizes chemical waste and prevents over-dosing.
  • Diagram:

    sequenceDiagram
        participant Sensors as IoT Sensors
        participant Controller as Local PLC
        participant CloudAI as AI Model
        participant Pumps as Reactant Pumps
    
        loop Real-time Loop
            Sensors->>CloudAI: Stream Water Quality Data
            CloudAI->>Controller: Send Optimized Pump Setpoints
            Controller->>Pumps: Adjust Flow Rates
            Pumps-->>Sensors: Affect Water Chemistry
        end
    

5. The "Inverse" or Failure Mode

• Derivative 1.8: Fail-Safe Shutdown and Dilution Mode
  • Enabling Description: The system incorporates a safety interlock based on pH and temperature probes located immediately after the alkali injection point. If the pH exceeds a setpoint of 13.5 or the temperature rises more than 15°C above the influent water temperature (indicating a potential for runaway reaction), the controller immediately performs two actions: 1) it shuts down the alkali pump, halting PAA generation, and 2) it opens a solenoid valve that floods the reaction chamber with bypass water, rapidly diluting any high-concentration reactants. An alarm is sent to the operator. This ensures that an equipment failure (e.g., stuck alkali pump) does not create a hazardous, high-concentration PAA solution.
  • Diagram:

    stateDiagram-v2
        state "Normal Operation" as Generating
        state "Safe Mode" as Flushing
        [*] --> Generating
        Generating --> Flushing: pH > 13.5 OR TempRise > 15C
        Flushing --> [*]: Operator Reset
        Generating --> [*]: Normal Shutdown
    

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Derivations Based on Independent Claim 20 (The Chemical Composition)

The core claim is a liquid composition of 23-40% H₂O₂, 20-52% triacetin, water, and a trace of PAA.

• Derivative 2.1: Gelled & Emulsified Compositions

  • Enabling Description: The claimed liquid composition is modified to alter its physical properties for specialized applications.
    • Gelled Version: Fumed silica or a polyacrylic acid thickener (e.g., Carbopol®) is added at 0.5-2.0% w/w to the hydrogen peroxide-triacetin mixture. This creates a viscous gel that is easier to handle and less prone to splashing. It is designed for cartridge-based systems where the gel is extruded and mixed with the alkali solution.
    • Emulsion Version: A non-ionic surfactant (e.g., a polysorbate or alkyl polyglycoside) is added at 1-5% w/w. This creates a stable oil-in-water emulsion. This formulation is designed for applications where the final PAA solution needs to have cleaning (surfactant) properties, such as in single-step clean-in-place (CIP) systems.
  • Diagram:

    classDiagram
      class PrecursorComposition {
        +hydrogenPeroxide: 23-40%
        +triacetin: 20-52%
        +water: balance
      }
      class GelledComposition {
        +thickener: "Fumed Silica"
        +viscosity: "500-2000 cP"
      }
      class EmulsifiedComposition {
        +surfactant: "Polysorbate 80"
        +isStable: true
      }
      PrecursorComposition <|-- GelledComposition
      PrecursorComposition <|-- EmulsifiedComposition
    

• Derivative 2.2: Composition with Integrated pH Indicator

  • Enabling Description: A pH-sensitive dye, such as thymolphthalein or indigo carmine, is dissolved into the hydrogen peroxide-triacetin precursor solution. The dye is selected to be stable in the acidic precursor environment but change color dramatically at the target alkaline pH of the reaction medium (pH > 11). For instance, thymolphthalein is colorless in the precursor but turns deep blue when the alkali is correctly added. This provides an immediate, visual confirmation that the PAA generation reaction has been successfully initiated, aiding in system diagnostics without electronic sensors.
  • Diagram:

    graph TD
        A[Precursor (H₂O₂ + Triacetin + Colorless Dye)] --> C{Mixer};
        B[Alkali (NaOH)] --> C;
        C --> D[Reaction Medium];
        subgraph "Visual Confirmation"
            D -- pH > 11 --> E{Deep Blue Color};
        end
    

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Combination Prior Art Scenarios

• Scenario 1: Integration with OPC-UA for Industrial Automation

  • Description: The PAA generation system described in Claim 1 is manufactured as a self-contained skid. The system's controller is designed to be an OPC-UA (Open Platform Communications Unified Architecture) server. This allows for seamless, vendor-neutral integration into a larger factory's SCADA (Supervisory Control and Data Acquisition) system. The SCADA system can monitor the PAA generator's status, flow rates, chemical tank levels, and alarms, and can enable or disable the unit as part of a fully automated clean-in-place (CIP) recipe for a food processing line. This combination renders obvious the application of this on-site generation method within the standard framework of modern industrial automation (IEC 62541).

• Scenario 2: Blockchain-Verified Chemical Supply Chain with W3C Credentials

  • Description: Each container of the hydrogen peroxide-triacetin precursor (Claim 20) and the alkali solution is given a unique serial number tied to a digital token on a permissioned blockchain. The manufacturer issues a W3C Verifiable Credential for each batch, attesting to its purity and concentration. When the PAA generation system consumes the chemicals, it records the volume used against the container's token on the blockchain. This creates an immutable audit trail for regulatory compliance (e.g., FDA, EPA), proving that only approved, non-expired chemicals were used to generate the sanitizer for treating foodstuffs. This renders obvious the integration of modern digital trust and supply chain standards with the chemical composition.

• Scenario 3: IoT System using MQTT for Lightweight Communication

  • Description: The AI-optimized PAA dosing system (Derivative 1.7) uses the MQTT (Message Queuing Telemetry Transport) protocol for all communication between the IoT sensors, the local controller, and the cloud-based AI model. MQTT is a lightweight, open-source publish/subscribe messaging protocol ideal for constrained devices and unreliable networks. The pH sensor publishes its readings to a topic like plant/paa_gen_1/ph, and the cloud AI subscribes to this topic. The AI then publishes new pump setpoints to a topic like plant/paa_gen_1/pumps/setpoint, which the local controller is subscribed to. This renders obvious the use of standard, open IoT protocols for controlling the on-site generation process.