Beta-cyclodextrin Polyamide Membranes for Nanofiltration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing nanofiltration membranes face challenges in efficiently rejecting salts and pharmaceutical micro-pollutants, with limitations in permeate flux and selectivity, particularly when using traditional monomers like MPD and PIP.
Innovation Solution
A multi-layered thin film composite nanofiltration membrane is developed, comprising a polysulfone substrate, a second layer of glucose-derived beta-cyclodextrin reacted with a tetramine and phthaloyl chloride, forming a polyamide layer through interfacial polymerization. This configuration enhances the membrane's hydrophilicity and porosity, improving salt rejection and micro-pollutant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional monomers (MPD and PIP) are used to fabricate nanofiltration membranes, then the membrane structure is simple and manufacturing is easier, but the rejection percentage for salts and pharmaceuticals is insufficient and permeate flux is limited
Solution Approach 1:
The patent employs a composite membrane structure combining polysulfone substrate with beta-cyclodextrin modified polyamide active layer. The beta-cyclodextrin molecules are grafted onto the polyamide chains formed by traditional monomers (MPD and PIP), creating a composite material that maintains the structural simplicity of conventional membranes while adding functional groups for enhanced rejection of salts and pharmaceuticals through host-guest inclusion complexes
Solution Approach 2:
The beta-cyclodextrin modification is applied locally to the polyamide active layer rather than throughout the entire membrane structure. The cyclodextrin units are incorporated into the active layer during interfacial polymerization, creating localized functional sites with high rejection capability while preserving the overall membrane architecture and maintaining ease of manufacturing
2Productivity
If the membrane porosity is increased to improve permeate flux, then water permeability improves, but salt rejection and micro-pollutant removal efficiency deteriorate
Solution Approach 1:
The patent utilizes beta-cyclodextrin units with inherent porous cavity structures (0.6-0.7 nm diameter) embedded within the polyamide active layer. These cyclodextrin cavities create selective pathways that allow water molecules to pass through while blocking larger salt ions and pharmaceutical molecules through size exclusion and host-guest inclusion mechanisms, thus achieving high permeate flux without sacrificing selectivity
Solution Approach 2:
The patent modifies the chemical parameters of the active layer by incorporating beta-cyclodextrin units with specific cavity dimensions and hydrophilic hydroxyl groups. This changes the pore size distribution, surface charge, and hydrophilicity of the membrane, enabling simultaneous achievement of high permeate flux (15-75 L m−2 h−1 at 5 bar) and high rejection percentages (80-95% for salts and 65-95% for pharmaceuticals)
3Productivity
If the active layer is made more hydrophilic to enhance water flux, then permeate flux increases, but the mechanical strength and structural stability of the membrane may be compromised
Solution Approach 1:
The beta-cyclodextrin units providing hydrophilicity are localized within the active layer structure, confined to specific regions where they interact with water molecules. The polyamide backbone maintaining mechanical integrity remains intact, with cyclodextrin units grafted as side chains. This localized hydrophilic modification enhances water flux while the underlying polyamide network preserves mechanical strength and structural stability
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 membrane achieves a high rejection percentage of 80-95% for salts and 65-95% for pharmaceuticals, along with a permeate flux of 15-75 L m−2 h−1 at 5 bar, demonstrating improved performance compared to traditional membranes.
Implementation Method 1
the presence of an additional —COOH group on the DABA, which developed a highly hydrophilic membrane
Implementation Method 2
The membrane achieves a high rejection percentage of 80-95% for salts and 65-95% for pharmaceuticals
Implementation Method 3
a TFC polyamide membrane is fabricated through IP using piperazine (PIP) as an aqueous amine crosslinked with TMC
Implementation Method 4
IP reaction is generally carried out between an aqueous diamine, such as meta-phenylenediamine (MPD), and a non-aqueous (n-hexane) solution of trimesoyl chloride (TMC)
Data Source
AI summary
A filtration membrane, including (in the following order) a thermoplastic substrate, a first layer including a polysulfone, a second layer including units of a glucose-derived polysaccharide reacted with units of a tetramine and units of a phthaloyl chloride. The units of the tetramine and the units of the phthaloyl chloride are reacted to form a polyamide (PA) and the units of glucose-derived polysaccharide are covalently bonded to the PA through reacted units of the phthaloyl chloride. A method of nanofiltration using the filtration membrane.