Degradation synergism between sonolysis and photocatalysis for organic pollutants with different hydrophobicity: A perspective of mechanism and application for high mineralization efficiency

Baekha Ryu, Kien Tiek Wong, Choe Earn Choong, Jung Rae Kim, Hyunook Kim, Sang Hyoun Kim, Byong Hun Jeon, Yeomin Yoon, Shane A. Snyder, Min Jang

Research output: Contribution to journalArticlepeer-review

Abstract

Despite extensive studies, the fundamental understanding of synergistic mechanisms between sonolysis and photocatalysis for the abatement of persistent organic pollutants (POPs) remains uncertain. As different phases formed under ultrasound irradiation, hydrophilic POPs, sulfamethoxazole (SMX, Kow: 0.89), predominantly resides in bulk liquid and is ineffectively degraded by sonolysis (kUS = 3.33 × 10−3 min−1) since <10% of hydroxyl radicals (·OH) formed at the gas-liquid interface of cavitation is diffused into the bulk, whereas the other fraction rapidly recombines into hydrogen peroxide (H2O2). This study provides a proof-of-concept for the mechanism by presenting various analytical results, endorsing the synergistic role of photoexcited electrons in splitting sonolysis-induced H2O2 into ·OH, particularly in the bulk phase. In a sonophotocatalytic system, the hydrophobic POPs such as bisphenol A (BPA) and atrazine (ATZ) were mainly degraded in gas-liquid interface indicated by the low synergistic values correlation compared to SMX [i.e., SMX has a higher synergistic factor, fsyn (3.26) than BPA (1.30) and ATZ (1.35)]. Also, fsyn was found linearly correlated with the contribution factor of photocatalysis to split H2O2. Three times of consecutive kinetics using an effluent of municipal (MP) wastewater spiked by POPs presented >98% POPs and >96% total organic carbon (TOC) removal.

Original languageEnglish (US)
Article number125787
JournalJournal of Hazardous Materials
Volume416
DOIs
StatePublished - Aug 15 2021

Keywords

  • Electrons
  • Hydrogen peroxide
  • Photocatalysis
  • Sonolysis
  • Synergistic

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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