Brine Purification via Ion Exchange Resins
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Solution Overview
Problem
Current membrane cell chlor-alkali processes face challenges in achieving stable and efficient performance due to high current densities, which require higher brine purity levels, particularly in removing aluminum and nickel cations that can deposit on membranes, leading to reduced membrane lifetime.
Innovation Solution
A cost-effective method involving pH adjustment of brine solutions to a range of 2-6, followed by contact with a mixture of cationic exchange resins containing aminophosphonic acid and iminodiacetic acid functional groups, at linear liquid velocities of 10-100 m/hr and temperatures of 10-90°C, to effectively reduce aluminum and nickel cation concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher current densities are used in membrane cell chlor-alkali processes, then productivity increases, but brine purity requirements increase leading to membrane deposition and shortened lifetime
Solution Approach 1:
The patent applies preliminary action by implementing a multi-step brine purification process before the membrane cell process. The process includes precipitation treatment to remove aluminum and nickel cations, followed by filtration, to pre-cleanup the brine and prevent subsequent membrane deposition. This preliminary purification enables higher current densities to be used without compromising membrane lifetime.
Solution Approach 2:
The patent applies parameter changes by optimizing multiple process parameters: pH control during precipitation (adjusting to specific ranges for optimal metal cation removal), temperature control in the purification process, and concentration thresholds for aluminum and nickel removal. By carefully controlling these parameters, the process achieves the required brine purity levels that enable high current density operation while protecting membrane lifetime.
2Manufacturing precision
If multiple separate treatment steps are used to remove different metal cations, then removal effectiveness increases, but device complexity and capital costs increase
Solution Approach 1:
The patent applies merging by combining multiple treatment functions into a single integrated precipitation unit. The process uses a single treatment step that simultaneously removes aluminum, nickel, and other metal cations through controlled precipitation, eliminating the need for multiple separate treatment units. This reduces device complexity and capital costs while maintaining effective metal cation removal.
Solution Approach 2:
The patent applies universality by designing a multi-functional precipitation process that can remove multiple types of metal cations (aluminum, nickel, and others) using a single treatment mechanism. The precipitation reagents and process conditions are optimized to simultaneously target various metal cations, making the treatment unit universally effective against multiple contaminants rather than requiring specialized units for each metal type.
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 method allows for simultaneous removal of both cations in a single unit operation, reducing capital and operating costs, and produces a brine feedstock with significantly lower aluminum and nickel levels, enhancing membrane cell performance and extending membrane lifetime.
Implementation Method 1
contacting the pH adjusted brine solution with a mixture of cationic exchange resins... produces a treated brine solution which contains less aluminum and nickel cations
Data Source
AI summary
The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.