Composite Membrane for Membrane Distillation
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Solution Overview
Problem
Membrane distillation techniques face challenges when processing wastewater containing surface active agents, as these agents can cause pore wetting and reduce membrane flux and water quality, particularly in dyeing wastewater from textile mills.
Innovation Solution
A composite membrane is developed, comprising a hydrophobic porous membrane with a high water content hydrogel layer on its hot surface, which blocks surface active agents, preventing pore wetting and maintaining membrane functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous membrane is used for membrane distillation, then water can be separated through vapor pressure deficit, but surface active agents in wastewater cause pore wetting that ceases membrane distillation function
Solution Approach 1:
The patent applies composite materials by combining a hydrophobic porous membrane with a hydrophilic gel layer to create a composite membrane structure. The hydrophobic membrane provides the distillation function while the hydrophilic gel layer captures surface active agents, resolving the contradiction between maintaining membrane function and preventing pore wetting.
Solution Approach 2:
The hydrophilic gel layer acts as an intermediary between the wastewater and the hydrophobic porous membrane. It intercepts and captures surface active agents before they can reach and wet the membrane pores, thereby protecting the membrane distillation function while allowing water vapor transport.
2Productivity
If a porous membrane is used for membrane distillation, then moisture can pass through from high temperature side to low temperature side, but membrane flux and water quality deteriorate when processing wastewater with surface active agents
Solution Approach 1:
The composite membrane structure combines the vapor transport capability of the porous membrane with the contaminant capture capability of the hydrophilic gel layer, maintaining both high membrane flux and good water quality when processing wastewater containing surface active agents.
Solution Approach 2:
The hydrophilic gel layer serves as a protective intermediary that prevents surface active agents from directly contacting the membrane pores, thereby maintaining membrane flux and ensuring water quality without compromising the distillation function.
3Adaptability or versatility
If conventional membrane distillation is used for dyeing wastewater, then high temperature wastewater can be treated, but chemical components cause membrane pollution and pore wetting
Solution Approach 1:
The composite membrane combines a heat-resistant hydrophobic porous membrane with a chemically active hydrophilic gel layer. This structure maintains the ability to treat high temperature wastewater while the gel layer specifically captures chemical components like leveling agents and softening agents that would otherwise cause membrane pollution.
Solution Approach 2:
The hydrophilic gel layer acts as a protective intermediary that selectively captures harmful chemical components in dyeing wastewater before they can contact and pollute the hydrophobic membrane, enabling effective treatment of high temperature wastewater with complex chemical compositions.
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 composite membrane effectively prevents pore wetting and maintains stable membrane flux and water quality during long-term membrane distillation of wastewater containing surface active agents, such as those found in dyeing wastewater, by capturing these agents with its high water content hydrogel layer.
Implementation Method 1
The surface active agents contained in the wastewater at the hot end are blocked by the high water content hydrogel layer
Implementation Method 2
the moisture passes through the pores of the porous membrane from the high temperature side to the low temperature side because of the vapor pressure deficit, which is generated by the temperature gradient
Implementation Method 3
the vapor pressure deficit, which is generated by the temperature gradient between the high temperature side and the low temperature side
Data Source
AI summary
A composite membrane includes a hydrophobic porous membrane and a high water content hydrogel layer disposed on the surface of the hydrophobic porous membrane facing the hot end. The surface active agents contained in the wastewater at the hot end are blocked by the high water content hydrogel layer, thus the problem of pore wetting of the hydrophobic porous membrane can be prevented. Therefore, the membrane distillation technique can be utilized for processing wastewater containing surface active agents.