TY - JOUR

T1 - Visible light-induced catalytic activation of peroxymonosulfate using heterogeneous surface complexes of amino acids on TiO2

AU - Lim, J.

AU - Kwak, D.-Y.

AU - Sieland, F.

AU - Kim, C.

AU - Bahnemann, D.W.

AU - Choi, W.

N1 - Funding information: This work was supported by Global Research Laboratory (GRL) Program (NRF-2014K1A1A2041044) and Basic Science Research Program (NRF-2017R1A2B2008952), which were funded by the Korea government (MSIP) through National Research Foundation of Korea (NRF). We appreciate the late Dr. Alok Bokare for his valuable discussion and comments.

PY - 2018/6/5

Y1 - 2018/6/5

N2 - Peroxymonosulfate (PMS) is being extensively investigated as an eco-friendly oxidant and various activation methods of PMS have been investigated. Here we demonstrated a new method of catalytic PMS activation, which employed amino acids as both a visible light sensitizer and a substrate to be degraded. Although PMS and amino acids do not absorb any visible light, the surface adsorption of amino acids on titania formed charge-transfer complexes that absorb visible light (λ > 420 nm). Serine and histidine were employed as main target amino acids and their surface complexes on TiO 2 were characterized by various spectroscopic methods The ligand-to-metal charge transfer between amino acids and TiO 2 enabled the absorption of visible light and the subsequent electron transfer catalytically activated PMS with generating sulfate radicals which were detected by electron paramagnetic resonance analysis. Based on various scavenger tests, amino acids seem to be degraded mainly by sulfate radical (radical pathway) and by a non-radical pathway (PMS serving primarily as an electron acceptor) to some extent. Amino acids were degraded with producing ammonium as a sole nitrogenous product in this process, whereas most advanced oxidation processes of amino acid generate not only ammonium but also nitrate and nitrite. The visible light-induced charge transfer characteristics of the amino acid-TiO 2 complexes were demonstrated by the photoelectrochemical characterizations and the time-resolved laser spectroscopic analysis.

AB - Peroxymonosulfate (PMS) is being extensively investigated as an eco-friendly oxidant and various activation methods of PMS have been investigated. Here we demonstrated a new method of catalytic PMS activation, which employed amino acids as both a visible light sensitizer and a substrate to be degraded. Although PMS and amino acids do not absorb any visible light, the surface adsorption of amino acids on titania formed charge-transfer complexes that absorb visible light (λ > 420 nm). Serine and histidine were employed as main target amino acids and their surface complexes on TiO 2 were characterized by various spectroscopic methods The ligand-to-metal charge transfer between amino acids and TiO 2 enabled the absorption of visible light and the subsequent electron transfer catalytically activated PMS with generating sulfate radicals which were detected by electron paramagnetic resonance analysis. Based on various scavenger tests, amino acids seem to be degraded mainly by sulfate radical (radical pathway) and by a non-radical pathway (PMS serving primarily as an electron acceptor) to some extent. Amino acids were degraded with producing ammonium as a sole nitrogenous product in this process, whereas most advanced oxidation processes of amino acid generate not only ammonium but also nitrate and nitrite. The visible light-induced charge transfer characteristics of the amino acid-TiO 2 complexes were demonstrated by the photoelectrochemical characterizations and the time-resolved laser spectroscopic analysis.

KW - Advanced oxidation process (AOP)

KW - Amino acid degradation

KW - Sulfate radical

KW - Surface complex

KW - Visible light activation of PMS

UR - http://www.scopus.com/inward/record.url?scp=85037994004&partnerID=8YFLogxK

U2 - 10.1016/j.apcatb.2017.12.025

DO - 10.1016/j.apcatb.2017.12.025

M3 - Article

VL - 225

SP - 406

EP - 414

JO - Applied Catalysis B: Environmental

JF - Applied Catalysis B: Environmental

SN - 0926-3373

ER -