Degradation of p-Nitrophenol by activated persulfate with carbon-based materials

Carmen S D Rodrigues; Sofia N A Aziz; M F R Pereira; O S G P Soares; Luís M Madeira

doi:10.1016/j.jenvman.2023.118140

Degradation of p-Nitrophenol by activated persulfate with carbon-based materials

J Environ Manage. 2023 Oct 1:343:118140. doi: 10.1016/j.jenvman.2023.118140. Epub 2023 May 25.

Authors

Carmen S D Rodrigues¹, Sofia N A Aziz², M F R Pereira³, O S G P Soares³, Luís M Madeira⁴

Affiliations

¹ LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. Electronic address: csdr@fe.up.pt.
² LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; Université de Lorraine, 34 Cours Léopold, 54000, Nancy, France.
³ ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; LSRE-LCM - Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
⁴ LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; ALiCE - Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. Electronic address: mmadeira@fe.up.pt.

PMID: 37244099
DOI: 10.1016/j.jenvman.2023.118140

Abstract

The removal of p-nitrophenol (PNP) from wastewater was evaluated by the activated persulfate process using different materials - carbon xerogels (XG), carbon nanotubes (CNT), and activated carbon (AC) -, and also using such materials doped with nitrogen (XGM, CNTM and ACM). These carbon materials were impregnated with 2 wt.% of iron and tested in the oxidative process to assess the influence of their textural and surface chemical properties. The carbon-based materials' properties influence the efficiencies of the adsorption and oxidative processes; in adsorption, the materials with higher specific surface areas (S_BET), i.e. AC (824 m²/g) and Fe/AC (807 m²/g), have shown to be the most promising (having achieved a PNP removal of about 20%); on the other hand, in the activated persulfate process the carbon or iron-containing carbon materials with the highest mesoporous areas (S_meso) were the preferential ones - XG and Fe/XG, respectively - reaching removals of 47.3% and 75.7% for PNP and 44.9 and 63.3% for TOC, respectively. Moreover, the presence of nitrogen groups on the samples' surface benefits both processes, being found that PNP degradation and mineralization increase with the nitrogen content. The stability of the best materials (XGM and Fe/XGM) was evaluated during four cycles, being noticed that while XGM lost catalytic activity, the Fe/XGM sample remained stable without leaching of iron. The quantification of intermediate compounds formed during persulfate oxidation was performed, and only oxalic acid was detected, in addition to PNP, being that their contribution to the TOC measured was higher than 99%. Experiments carried out in the presence of radical scavengers proved that only the sulfate radical is present under the acidic conditions used. Complete PNP oxidation and TOC removal of ∼96% were reached for the activated persulfate process, proving to be more attractive than the Fenton one.

Keywords: Activated persulfate; Carbon-based materials; Mineralization; Textural and chemical surface properties; p-Nitrophenol degradation.

MeSH terms

Charcoal
Iron / chemistry
Nanotubes, Carbon*
Nitrogen
Oxidation-Reduction
Water Pollutants, Chemical* / chemistry

Substances

4-nitrophenol
Nanotubes, Carbon
Water Pollutants, Chemical
Iron
Charcoal
Nitrogen