A Solar-Enabled Strategy for Degrading Allura Red AC Using a Laddered Heterojunction Nanocomposite.

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Allura Red AC, a synthetic azo dye, poses environmental and health risks due to its persistence and resistance to conventional treatments.
• Effective degradation methods are crucial for managing dye-contaminated wastewater from food and textile industries.

Purpose of the Study:

• To develop and evaluate a solar-active nanocomposite for the efficient photocatalytic degradation of Allura Red AC.
• To investigate the degradation mechanism and assess the catalyst's stability and reusability.

Main Methods:

• Synthesis of a silver-coated cobalt-substituted zinc ferrite integrated with zinc oxide (Ag-CZFO/ZnO) nanocomposite via microwave-assisted solvothermal method.
• Photocatalytic degradation experiments under optimized conditions, including pH, catalyst loading, and dye concentration.
• Analysis of degradation pathways using scavengers and reactive oxygen species probe experiments; assessment of catalyst stability through reuse cycles.

Main Results:

• The Ag-CZFO/ZnO nanocomposite achieved 96% degradation of Allura Red AC within 150 minutes, with a rate constant of 0.0188 min⁻¹.
• The catalyst exhibited broad light absorption up to 925 nm and demonstrated significant reduction in chemical oxygen demand, indicating near-complete mineralization.
• Photogenerated holes, along with hydroxyl and superoxide radicals, were key to the degradation process; the catalyst showed high stability over five reuse cycles.

Conclusions:

• The developed solar photocatalyst is a sustainable and effective solution for degrading persistent organic pollutants like Allura Red AC.
• The nanocomposite's laddered heterojunction structure enhances charge separation and transfer, improving photocatalytic efficiency.
• This sunlight-driven approach offers a promising method for large-scale industrial wastewater treatment.