Colloidal activated carbon as a highly efficient bifunctional catalyst for phenol degradation.

Area of Science:

• Environmental Chemistry
• Materials Science
• Catalysis

Background:

• Phenol contamination in groundwater poses significant environmental and health risks.
• Conventional remediation methods often involve metal catalysts, which can lead to secondary pollution.
• There is a need for efficient, metal-free catalysts for advanced oxidation processes.

Purpose of the Study:

• To introduce colloidal activated carbon (CAC) as a metal-free catalyst for phenol remediation.
• To investigate the efficiency of CAC in activating persulfate (PS) for phenol degradation.
• To elucidate the mechanism of phenol removal using CAC.

Main Methods:

• Preparation of colloidal activated carbon (CAC) via pulverization.
• Phenol removal experiments using persulfate (PS) with CAC, activated carbon (AC), and Fe2+.
• Kinetic analysis using the Langmuir-Hinshelwood (L-H) model.
• Characterization using Fourier-transform infrared spectroscopy (FT-IR) and electron spin resonance (ESR).

Main Results:

• PS/CAC system achieved ~100% phenol removal within 30 minutes, outperforming PS/AC (90.1%) and PS/Fe2+ (27.9%).
• Phenol degradation occurred in both bulk solution and on the CAC surface.
• Superoxide radical (O2•−) was identified as the predominant reactive species in the PS/CAC system.
• Ferulic acid was detected as an oxidation byproduct.

Conclusions:

• Colloidal activated carbon (CAC) is a highly effective metal-free catalyst for persulfate activation.
• The enhanced performance of CAC is attributed to its high surface area and ability to generate superoxide radicals.
• CAC presents a promising sustainable solution for groundwater phenol remediation.