Sustainable polyelectrolyte multilayer surfaces: possible matrix for salt/dye separation.

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Developing sustainable membranes is crucial for advanced analytical separations.
• Chitosan/poly(acrylic acid) (CHI/PAA) multilayers offer potential for tailored membrane properties.
• Existing low-pressure membranes often face trade-offs between flux and selectivity.

Purpose of the Study:

• To develop a sustainable membrane surface using CHI/PAA multilayers for analytical separations.
• To investigate the performance of these membranes under low-pressure filtration conditions.
• To explore the impact of feed composition on membrane stability and separation efficiency.

Main Methods:

• Layer-by-layer assembly of CHI/PAA multilayers on polyamide microfiltration membranes.
• Low-pressure filtration experiments to measure flux and selectivity.
• Analysis of membrane morphology using scanning electron microscopy (SEM).
• Investigation of transport phenomena with varying salt and dye concentrations.

Main Results:

• A 5.5 bilayer membrane achieved high flux (7 m³ m⁻² day⁻¹) and selectivity (>8000 for NaCl/RB5) at 10 psi.
• Membrane flux increased with feed salt concentration due to morphological transformations.
• The presence of reactive black 5 (RB5) dye enhanced membrane sustainability and performance.
• A 50 nm skin layer provided a large separation window, with 98.64% RB5 rejection at 25.79 m³ m⁻² day⁻¹.

Conclusions:

• The CHI/PAA multilayer membranes offer superior flux and selectivity for low-pressure analytical separations.
• The membrane's performance and sustainability are significantly influenced by feed composition, particularly dye concentration.
• The study demonstrates a promising approach for creating robust and efficient separation membranes.