Silica-Based RO Membranes for Separation of Acidic Solution

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Technology

Background:

• Acid separation membranes are crucial for industrial processes.
• Traditional membranes often lack stability in highly acidic environments.
• Sulfuric acid solutions pose significant challenges for membrane integrity.

Purpose of the Study:

• To develop robust silica-based membranes for sulfuric acid separation.
• To enhance the acid stability of reverse osmosis (RO) membranes.
• To investigate the performance of membranes on improved substrates.

Main Methods:

• Utilized counter diffusion chemical vapor deposition (CVD) for membrane fabrication.
• Employed diphenyldimethoxysilane (DPhDMOS) as a silica precursor.
• Tested membrane stability using sulfuric acid immersion and gas permeation.

Main Results:

• Achieved 81% sulfuric acid rejection with a flux of 5.8 kg m⁻² h⁻¹ at low concentrations.
• Identified substrate damage with γ-alumina in sulfuric acid solutions.
• Silica substrates demonstrated superior acid stability, with only an 11% decrease in N₂ permeance post-treatment.
• DPhDMOS-derived membranes on silica substrates maintained stable performance in 70 wt% sulfuric acid.

Conclusions:

• Silica-based membranes fabricated via CVD offer enhanced stability for sulfuric acid separation.
• The use of silica substrates significantly improves membrane durability in acidic conditions.
• These findings pave the way for more resilient membranes in demanding chemical applications.