PAN-PVDF Nanofiber Filter Medium for Water Treatment
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Solution Overview
Problem
Current filter media face challenges in achieving high mechanical strength, chemical resistance, and hydrophilicity while maintaining spinnability, especially when trying to filter finer particles, and existing methods for improving hydrophilicity often result in increased costs and process complexities.
Innovation Solution
A nanofiber filter medium composed of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) with a nonionic emulsifying agent is developed, which improves miscibility and hydrophilicity without separate surface modifications, enhancing mechanical strength and chemical resistance through electrospinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF nanofiber is used to ensure mechanical strength and chemical resistance, then structural stability is improved, but hydrophilicity deteriorates due to high hydrophobicity of PVDF
Solution Approach 1:
The patent uses a composite material system consisting of PVDF nanofibers combined with hydrophilic polymers (polyacrylonitrile, polyacrylic acid, or polyacrylamide) to simultaneously achieve mechanical strength, chemical resistance, and hydrophilicity. The hydrophilic polymer forms a coating layer on the PVDF nanofiber surface, creating a composite structure that combines the advantages of both materials.
Solution Approach 2:
The invention applies local quality modification by coating only the surface of the PVDF nanofiber with hydrophilic polymer. The core PVDF structure maintains its mechanical strength and chemical resistance, while the surface coating layer provides the necessary hydrophilicity for improved flux.
2Productivity
If hydrophilic functional groups are introduced to improve flux, then hydrophilicity is improved, but process complexity and cost increase due to separate surface modification
Solution Approach 1:
The patent merges the fiber formation process with the hydrophilicity enhancement process by incorporating hydrophilic polymers directly into the spinning solution. This eliminates the need for separate surface modification steps, simplifying the overall process while achieving both structural integrity and improved flux.
Solution Approach 2:
The hydrophilic polymer is pre-mixed with the PVDF in the spinning solution before electrospinning. This preliminary action ensures that the hydrophilic component is already distributed throughout the fiber structure, eliminating the need for subsequent surface treatment steps.
3Productivity
If two types of polymer compounds are coated to improve hydrophilicity, then flux is improved, but reliability deteriorates due to interfacial separation and peeling
Solution Approach 1:
The patent uses a single-type hydrophilic polymer coating system rather than multiple different polymer compounds. This homogeneous approach prevents interfacial separation and peeling issues that arise from incompatible polymer interfaces, while still achieving the desired hydrophilicity and flux improvement.
4Manufacturing precision
If microfibers with nanoscale diameter are used to achieve fine pore structure, then filtration precision is improved, but manufacturing difficulty increases due to complex spinning requirements
Solution Approach 1:
The patent changes the physical-chemical parameters of the spinning solution by adding hydrophilic polymers, which improve the miscibility and spinnability of the system. This enables the formation of uniform nanoscale microfibers with fine pore structures while simplifying the spinning process through better solution homogeneity and fiber formation characteristics.
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 nanofiber filter medium exhibits improved hydrophilicity, mechanical strength, and chemical resistance, leading to increased flux and filtration efficiency, while also simplifying the production process and reducing costs due to superior spinnability.
Implementation Method 1
it is necessary to be spun as island-in-the-sea yarns or the like and separately eluting a sea component to obtain an island component which is a microfiber
Implementation Method 2
A filter medium may be classified into a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, a nano-filter (NF) medium or a reverse osmosis (RO) membrane depending on pore size
Data Source
AI summary
A nanofiber for a filter medium is provided that includes fiber-forming ingredients including polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) and an emulsifying agent for improving the miscibility of the fiber-forming ingredients. The nanofiber has excellent mechanical strength and chemical resistance and, at the same time, significantly increased hydrophilicity without a separate surface modification/treatment to/on the nanofiber. A filter medium comprising said nanofiber can exhibit improved flux and filtration efficiency and excellent physical properties in a water treatment process in which a pressure equal to or more than a predetermined level is applied and which requires the filter medium to have high mechanical strength and in a water treatment process which requires chemical resistance as the liquid being filtered is strongly acidic or alkaline. Further, since the nanofiber has significantly superior spinnability, the mass productivity of the filter medium is significantly improved, and the unit costs of production can be reduced.