Pickering emulsion catalysis in a continuous flow system for methyl orange degradation

Area of Science:

• Environmental Chemistry
• Materials Science
• Chemical Engineering

Background:

• Pickering emulsions offer unique interfacial environments for catalysis.
• Heterogeneous catalysts are crucial for efficient and sustainable chemical processes.
• Conventional Fenton processes face limitations in efficiency and continuous operation.

Purpose of the Study:

• To develop a continuous-flow Fenton oxidation system using Pickering emulsions.
• To utilize a nickel-aluminum layered double hydroxide/graphene composite as both emulsifier and catalyst.
• To assess the system's efficiency in degrading methyl orange.

Main Methods:

• Formation of an oil-in-water Pickering emulsion stabilized by a Ni-Al layered double hydroxide/graphene composite.
• Implementation of a continuous-flow reactor system.
• Degradation of methyl orange and assessment of removal efficiency over time.
• Comparison with a conventional batch Fenton process.

Main Results:

• The Pickering emulsion system achieved >97% methyl orange degradation in 8 hours.
• Sustained removal efficiency of ~90% was maintained over 50 hours of continuous operation.
• The system significantly outperformed a conventional batch Fenton process (~44% degradation).

Conclusions:

• Pickering emulsion-based continuous reactors are a robust and scalable strategy for efficient organic pollutant removal.
• The composite material acts as both an effective emulsifier and a heterogeneous Fenton catalyst.
• Coupled adsorption and catalytic oxidation at the oil-water interface enhance degradation efficiency.