Eco-Friendly OSN Membranes Based on Alginate Salts with Variable Nanofiltration Properties

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Science

Background:

• Organic solvents nanofiltration (OSN) is crucial for separating valuable compounds.
• Conventional OSN membranes often rely on toxic reagents and non-biodegradable synthetic polymers.
• There is a growing need for sustainable and environmentally friendly membrane technologies.

Purpose of the Study:

• To fabricate and characterize novel OSN membranes using sodium alginate, a natural polymer.
• To investigate the influence of different cations on membrane performance in various organic solvents.
• To demonstrate the potential of alginate-based membranes as a sustainable alternative to synthetic membranes.

Main Methods:

• Sodium alginate was cross-linked with various divalent and trivalent metal cations (Cu2+, Fe3+, Cr3+, Al3+, Zn2+, Ca2+).
• Membrane performance was evaluated for the separation of RemazolBrilliant Blue dye from ethanol, DMF, and MP.
• Key performance indicators such as rejection (R) and permeability were measured.

Main Results:

• Alginate membranes exhibited excellent chemical stability in organic solvents, including aprotic polar solvents.
• Membrane properties were effectively tuned by changing the cross-linking cation.
• Iron alginate membranes achieved 97% rejection and 1.5 kg·m−2·h−1·bar−1 permeability for dye separation from ethanol.
• Calcium alginate membranes showed ~90% rejection and 0.1-0.2 kg·m−2·h−1·bar−1 permeability for separation from DMF and MP.

Conclusions:

• Sodium alginate-based membranes are a safe, environmentally friendly, and cost-effective alternative for OSN.
• Tunable properties through cation selection allow for tailored separation performance in different organic solvents.
• These biodegradable membranes show competitive performance against synthetic polymer-based membranes.