Electrically Conductive Membrane AC Scaling Prevention
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Solution Overview
Problem
Membrane-based desalination technologies face significant challenges due to mineral scaling, which restricts water passage and physically damages membranes, particularly in groundwater desalination where multivalent ions form sparingly soluble minerals, leading to reduced water recovery and efficiency in industrial processes like heat exchangers.
Innovation Solution
The implementation of electrically conductive membranes with a percolating network of carbon nanotubes cross-linked with a polymer, applying an alternating current to prevent mineral scaling by controlling ion concentrations and delaying crystallization, thereby minimizing flux decline and increasing water recovery without a significant energy penalty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If membrane-based desalination is used to produce fresh water from saltwater, then energy efficiency is improved, but mineral scale formation occurs on the membrane surface
Solution Approach 1:
The patent applies periodic action by using alternating current (AC) to periodically reverse the electrical potential on the membrane surface. This periodic reversal prevents the accumulation of ions and delays crystallization of sparingly soluble salts, thereby preventing mineral scale formation while maintaining the energy-efficient membrane desalination process.
Solution Approach 2:
The patent changes the electrical parameter of the membrane surface by applying an external electrical potential through AC power. This parameter change (electrical potential) alters the behavior of ions near the membrane surface, preventing them from accumulating and forming scale, thus resolving the contradiction between energy efficiency and scale prevention.
2Productivity
If water recovery is increased in groundwater desalination, then economic efficiency is improved, but mineral scaling blocks membrane pores and restricts water passage
Solution Approach 1:
The patent applies preliminary action by pre-treating the membrane surface with electrical potential before mineral scale can form. The AC electrical field acts preemptively to repel ions and prevent nucleation of sparingly soluble salts, allowing the system to achieve high water recovery without subsequent pore blockage issues.
Solution Approach 2:
The patent replaces mechanical mixing or chemical treatment with an electrical field approach. By using AC electrical potential on the membrane surface, the system substitutes mechanical/chemical methods with an electrical mechanism to prevent scale formation, enabling high water recovery while maintaining pore openness.
3Speed
If heterogeneous precipitation occurs on the membrane surface, then rapid mineral scale formation occurs, but this blocks water passage and damages membrane structure
Solution Approach 1:
The patent converts the harmful rapid heterogeneous precipitation into a beneficial controlled process. By applying AC electrical potential, the rapid precipitation is redirected away from the membrane surface into the bulk solution, where it can occur without damaging the membrane. The electrical field transforms the harmful scale-forming tendency into a controlled precipitation process that protects the membrane.
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
The use of electrically conductive membranes with alternating current effectively reduces mineral scaling, maintaining high water recovery and salt rejection, and demonstrates applicability to both synthetic and natural brackish groundwater, as well as other scaling-prone systems like heat exchangers, with improved reversibility and reduced chemical usage.
Implementation Method 1
applying an electrical potential to the electrically conductive membrane
Implementation Method 2
controlling ion concentrations and delaying crystallization
Implementation Method 3
delaying crystallization, thereby minimizing flux decline
Implementation Method 4
The application of alternating current (AC) to the membrane surface successfully controls the formation of mineral crystals and membrane fouling through induced electrophoretic mixing
Implementation Method 5
Membrane-based desalination technologies have been demonstrated to be the most energy efficient methods to produce fresh water from saltwater
Data Source
AI summary
A membrane desalination system includes a housing, an electrically conductive membrane disposed within the housing, wherein the electrically conductive membrane includes a porous support and an electrically conductive layer disposed on the porous support, and the electrically conductive layer includes nanostructures, and an alternating current power source connected to the electrically conductive membrane.