Ascorbic acid induced activation of persulfate for pentachlorophenol degradation.

Area of Science:

• Environmental Chemistry
• Oxidation Processes
• Water Treatment

Background:

• Organic pollutants, such as pentachlorophenol (PCP), pose significant environmental risks.
• Persulfate activation is a promising advanced oxidation process for pollutant degradation.
• Developing efficient and cost-effective methods for persulfate activation is crucial.

Purpose of the Study:

• To investigate the catalytic activity of ascorbic acid (AA) in activating persulfate for organic pollutant oxidation.
• To explore the underlying mechanisms and influencing factors of AA-induced persulfate activation.
• To evaluate the potential of this method for treating organochlorine-contaminated water.

Main Methods:

• Experimental investigation of pentachlorophenol (PCP) degradation using ascorbic acid (AA) and persulfate.
• Electron paramagnetic resonance (EPR) spectroscopy to identify generated radicals.
• Quenching experiments to determine the contribution of different reactive oxygen species (ROSs).
• Systematic study of influencing factors including AA concentration, pH, and AA ionization state.

Main Results:

• Ascorbic acid (AA) demonstrated significant catalytic activity, achieving 71.3% PCP degradation compared to 15.4% with persulfate alone.
• Sulfate (SO4•−) and hydroxyl (•OH) radicals were identified as the key ROSs responsible for PCP decomposition.
• PCP degradation was dependent on AA concentration and pH, with optimal performance under neutral conditions.
• Excess AA and high pH (above 12.5) inhibited degradation, while the ionized form of AA influenced activation efficiency.

Conclusions:

• Ascorbic acid (AA) is an effective catalyst for persulfate activation, significantly enhancing pentachlorophenol (PCP) degradation.
• The AA-persulfate system generates sulfate and hydroxyl radicals, contributing to efficient organic pollutant removal.
• This method shows high potential for the treatment of organochlorine-contaminated water, with performance influenced by pH and AA concentration.