Derivative works — US Patent 9737072

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.

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.

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
```

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
```

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.