PLA Membrane Composition Using DES for Oil-Water Separation
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Solution Overview
Problem
Conventional membrane fabrication methods for water treatment using petroleum-derived polymers and toxic solvents like N-methyl-2-pyrrolidone (NMP) or Dimethylacetamide (DMAc) pose environmental and health risks, necessitating the development of eco-friendly alternatives that maintain or improve membrane performance.
Innovation Solution
The use of biodegradable polymers such as polylactic acid (PLA) and green solvents like dimethyl sulfoxide (DMSO) combined with deep eutectic solvents (DES) to form ultrafiltration membranes through non-solvent induced phase separation, enhancing membrane porosity and oil rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional petroleum-derived polymers and toxic solvents (NMP, DMAc) are used in membrane fabrication, then membrane performance is achieved, but environmental harm and health risks increase
Solution Approach 1:
The patent changes the chemical composition parameters by substituting toxic solvents (NMP, DMAc) with green solvents (ethanol, water, isopropanol) and using biodegradable polymers (chitosan, cellulose, starch) instead of petroleum-derived polymers. This parameter change maintains membrane formation capability while eliminating harmful substances from the fabrication process.
Solution Approach 2:
The patent employs biodegradable polymers that can be naturally decomposed after use, eliminating the need for long-term disposal concerns. These polymers (chitosan, cellulose, starch) break down into harmless substances, replacing persistent synthetic polymers with environmentally friendly alternatives that don't accumulate in the environment.
2Object-affected harmful factors
If green solvents and biodegradable polymers are used to fabricate membranes, then environmental friendliness is improved, but membrane porosity and separation performance may be compromised
Solution Approach 1:
The patent creates composite membrane materials by combining multiple biodegradable polymers (e.g., chitosan-cellulose-starch composites) with appropriate pore-forming agents and crosslinking agents. This composite approach allows optimization of both environmental properties and separation performance, as the synergistic interaction of multiple materials enables fine-tuned pore structure and selective permeability.
Solution Approach 2:
The patent applies local quality modification by using crosslinking agents to create localized crosslinked structures within the membrane matrix. This creates regions of different density and permeability - the crosslinked regions provide structural integrity and selective separation, while the non-crosslinked regions maintain porosity for fluid transport. This spatial variation in material properties optimizes both environmental friendliness and separation performance.
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 resulting membranes exhibit high water permeability and oil rejection, supporting sustainable water treatment with reduced environmental impact and improved scalability.
Implementation Method 1
fabricating an ultrafiltration membrane from PLA, dimethyl sulfoxide (DMSO) and one or more deep eutectic solvents (DES) using non-solvent induced phase separation
Implementation Method 2
immersing the plate in a coagulation bath to form a porous PLA membrane
Data Source
AI summary
A method of fabricating an eco-friendly, porous membrane includes preparing a porous membrane using a dope solution of polymer, dimethyl sulfoxide (DMSO), and one or more deep eutectic solvents (DES). The porous PLA membrane can be formed from the dope solution through non-solvent induced phase separation (NIPS). A concentration of the one or more deep eutectic solvents in the dope solution can be between about 0.5 and 3.0 weight percent. The one or more deep eutectic solvents results in the membrane having increased porosity and a larger average pore size diameter. In an example, the one or more deep eutectic solvents includes choline chloride (ChCl) and ethylene glycol (EG). In an example, the membrane can be used for oil-water separation and the oil rejection of the membrane is at least 80 percent.