Conductive Diamond Anode High Current Density Oxidant Generation
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Solution Overview
Problem
Existing On-Site Generation (OSG) systems for oxidants face limitations due to premature electrode oxidation, scaling issues, and high maintenance costs, particularly when operating at high current densities, which restricts their efficiency and reliability, and require expensive purified feedstocks to avoid scaling and fouling.
Innovation Solution
The use of conductive diamond electrodes in electrochemical cells operating at high current densities (150 mA/cm2 to 1000 mA/cm2) with periodic reverse polarity cleaning cycles, allowing for efficient generation of oxidants like hypochlorite and mixed oxidants from impure salt feedstocks, such as seawater, without the need for expensive purification or water softeners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional DSA electrodes are operated at high current density to increase oxidant output, then productivity increases, but electrode lifetime is significantly reduced due to premature oxidation and degradation
Solution Approach 1:
The patent changes the fundamental material parameter of the electrode from conventional DSA (dimensionally stable anode) to diamond coating material. This material parameter change enables operation at high current densities (up to 1000 mA/cm²) without the premature oxidation and degradation that limits DSA electrodes, thereby simultaneously achieving high productivity and extended electrode lifetime
Solution Approach 2:
The patent employs a composite electrode structure consisting of a conductive substrate (such as titanium or stainless steel) coated with diamond material. This composite structure combines the electrical conductivity of the metal substrate with the exceptional chemical stability and oxidation resistance of diamond, enabling high current density operation while maintaining long electrode lifetime
2Reliability
If periodic reverse polarity operation is implemented to clean electrodes and reduce scaling, then reliability and ease of operation improve, but device complexity increases due to additional control requirements
Solution Approach 1:
The patent implements periodic reverse polarity operation where the electrode polarity is automatically reversed at predetermined time intervals or when scaling is detected. During reverse polarity periods, the previously cathodic electrode becomes anodic and undergoes oxidation that removes scale deposits. This periodic action maintains electrode performance and system reliability without requiring complex real-time control systems
Solution Approach 2:
The system performs self-cleaning through the reverse polarity operation, where the electrodes clean themselves by undergoing oxidation during reverse polarity periods. This eliminates the need for external cleaning mechanisms or manual intervention, improving reliability while keeping the control system relatively simple
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances current efficiency by 10-20%, extends electrode lifetime, reduces energy requirements, and enables the use of low-cost, impure feedstocks, resulting in more compact, cost-effective, and low-maintenance systems capable of producing high concentrations of oxidants with improved disinfection capabilities.
Implementation Method 1
electrolyzing the aqueous feedstock electrolyte at a current density in the range from 150 mA/cm2 to 1000 mA/cm2
Implementation Method 2
at least the anode being a conductive diamond anode
Implementation Method 3
periodic reversal of the polarity of the anode and cathode diminishes oxidation of the anode and reduces scaling and deposits of impurities
Data Source
AI summary
An electrochemical system and method are disclosed for On Site Generation (OSG) of oxidants, such as free available chlorine, mixed oxidants and persulfate. Operation at high current density, using at least a diamond anode, provides for higher current efficiency, extended lifetime operation, and improved cost efficiency. High current density operation, in either a single pass or recycle mode, provides for rapid generation of oxidants, with high current efficiency, which potentially allows for more compact systems. Beneficially, operation in reverse polarity for a short cleaning cycle manages scaling, provides for improved efficiency and electrode lifetime and allows for use of impure feedstocks without requiring water softeners. Systems have application for generation of chlorine or other oxidants, including mixed oxidants providing high disinfection rate per unit of oxidant, e.g. for water treatment to remove microorganisms or for degradation of organics in industrial waste water.