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Heterogeneous activation of persulfate by reduced graphene oxide–elemental silver/magnetite nanohybrids for the oxidative degradation of pharmaceuticals and endocrine disrupting compounds in water
Citation:
Park, C., J. Heo, D. Wang, C. Su, AND Y. Yoon. Heterogeneous activation of persulfate by reduced graphene oxide–elemental silver/magnetite nanohybrids for the oxidative degradation of pharmaceuticals and endocrine disrupting compounds in water. APPLIED CATALYSIS B: ENVIRONMENTAL. Elsevier Science Ltd, New York, NY, 225:91-99, (2018). https://doi.org/10.1016/j.apcatb.2017.11.058
Impact/Purpose:
It is important to develop and improve catalysts to speed up the destruction of organic contaminants such as pharmaceuticals and endocrine disrupting compounds in wastewater. Our study shows that reduced graphene oxide–elemental silver/magnetite nanohybrids enhanced the catalytic removal of phenol acetaminophen, ibuprofen, naproxen, bisphenol A, 17β-estradiol, and 17α-ethinyl estradiol in the heterogeneous activation of peroxydisulfate. This may have great applications for removal of organic compounds in water and wastewater treatment to meet regulatory requirements.
Description:
Reduced graphene oxide hybridized with zero-valent silver and magnetite nanoparticles (NPs) (rGO-Ag0/Fe3O4 nanohybrids) prepared via in situ nucleation and crystallization was used to activate peroxydisulfate (PDS) for degradation of pharmaceuticals and endocrine disrupting compounds (phenol, acetaminophen, ibuprofen, naproxen, bisphenol A, 17β-estradiol, and 17α-ethinyl estradiol). The deposition of Ag0 and Fe3O4 in rGO nanosheet enhanced the catalytic removal of phenol in the heterogeneous activation of PDS. The adsorption capacities of rGO-Ag0/Fe3O4 for 10 μM phenol were 1.76, 1.33, and 2.04 μmol g-1-adsorbent at pH 4, 7, and 10, respectively, which are much higher than those of single NPs studied (Ag0, nanoscale zero-valent iron, and rGO). The rGO-Ag0/Fe3O4 effectively activated PDS to produce strong oxidizing SO4•– radicals and facilitate an electron transfer on the surface of the nanohybrid. The initial pseudo-first-order rate (kini) constant for phenol degradation in PDS/rGO-Ag0/Fe3O4 system was 0.46 h–1 at pH 7, which is approximately eight times higher than that in the presence of single NPs (kini = 0.04-0.06 h–1) due to the synergistic effects between adsorption and catalytic oxidation. Among various organic contaminants tested, the simultaneous use of rGO-Ag0/Fe3O4 (0.1 g/L) and PDS (1 mM) achieved more than 99% degradation of acetaminophen and 17β-estradiol at pH 7. The SO4•– scavenging studies with methanol and natural organic matter indicated that phenol was more likely to be degraded via metal-bound SO4•– radicals formation or a non-radical oxidative pathway. Our findings indicate that the rGO-Ag0/Fe3O4 nanohybrids can be used as an efficient magnetically-separable nanocatalyst for removal of organic compounds in water and wastewater treatment.
URLs/Downloads:
DOI: Heterogeneous activation of persulfate by reduced graphene oxide–elemental silver/magnetite nanohybrids for the oxidative degradation of pharmaceuticals and endocrine disrupting compounds in water
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