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

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Carmen Rodrigues (Author) FEUP; Aziz, SNA (Author) Other; Manuel Fernando R Pereira (Author) FEUP; O.S.G.P. Soares (Author) FEUP; Luis Madeira (Author) FEUP

Journal

Title: Journal of Environmental Management

Vol. 343

ISSN: 0301-4797

Publisher: Elsevier

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Other information

Authenticus ID: P-00Y-MTW

DOI: 10.1016/j.jenvman.2023.118140

Abstract (EN): 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 (SBET), i.e. AC (824 m(2)/g) and Fe/AC (807 m(2)/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 mes-oporous areas (Smeso) 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 similar to 96% were reached for the activated persulfate process, proving to be more attractive than the Fenton one.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11