Selective separation of dye/salt mixture using diatomite-based sandwich-like membrane

Area of Science:

• Materials Science
• Environmental Engineering
• Chemical Engineering

Background:

• Developing efficient membranes for water purification is crucial.
• Nanofibrous membranes offer unique properties for separation processes.
• Diatomaceous earth is an abundant and cost-effective material.

Purpose of the Study:

• To develop a novel nanofiltration membrane with enhanced separation capabilities.
• To investigate the adsorption and separation performance of the membrane for methylene blue (MB).
• To evaluate the membrane's stability and reusability.

Main Methods:

• Fabrication of a sandwich-like membrane using modified diatomaceous earth and electrospun polysulfone (E-PSf) nanofibers.
• Characterization using FTIR, SEM, EDS, zeta potential, and water contact angle.
• Testing static adsorption and dynamic separation of MB under various conditions (pH, pressure, salt concentration).

Main Results:

• The Langmuir model accurately described MB adsorption isotherm data (R² >0.9955).
• Optimal conditions (gravity-driven) yielded high MB rejection (99.7%) and flux (183.8 LMH) at increased pH.
• Excellent dye/salt separation was achieved at high salt concentrations (>99% MB rejection, <0.2% NaCl rejection).
• High pressure increased water flux significantly but reduced MB rejection.

Conclusions:

• The developed sandwich-like membrane demonstrates excellent performance for MB removal and dye/salt separation.
• The membrane exhibits good stability and reusability over multiple cycles.
• This novel membrane holds promise for efficient wastewater treatment applications.