Janus amphiphilic carbon nanotubes as Pickering interfacial catalysts for the treatment of oily wastewater by selective oxidation with hydrogen peroxide

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Jose L. Diaz de Tuesta (Author) Other; Bruno F. Machado (Author) FEUP; Philippe Serp (Author) Other; Adrián M. T. Silva (Author) FEUP; Joaquim L. Faria (Author) FEUP; Helder T. Gomes (Author) Other

Journal

Title: Catalysis Today

Pages: 1-11

ISSN: 0920-5861

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 5 Citations

Scopus - 7 Citations

Other information

Authenticus ID: P-00Q-TPY

DOI: 10.1016/j.cattod.2019.07.012

Abstract (EN): Janus-like amphiphilic carbon nanotubes (CNTs) were tested as catalysts in the oxidation of 2-nitrophenol (2-NP) with hydrogen peroxide. A biphasic oil-water medium was used to simulate oily wastewater contaminated with the lipophilic model pollutant 2-NP. The CNTs were synthesized by sequentially feeding ethylene and/or acetonitrile, used as carbon and carbon/nitrogen precursors, respectively. The results obtained for 2-NP removal using biphasic systems were compared with those obtained by CWPO using aqueous solutions. The most active catalyst in the CWPO of 2-NP in aqueous solution was the CNT synthesized only with ethylene. This was explained by its high lipophilic character, allowing the complete removal of 2NP after 24 h of reaction at 50 °C, pH0 = 3, Ccat = 0.25 g L¿1, C2-NP,0 = 0.5 g L¿1 and the stoichiometric quantity of H2O2 needed for the total mineralization of 2-NP. For the oxidation of 2-NP in biphasic medium, only the Janus-like amphiphilic CNTs (containing a lipophilic undoped section synthetized from ethylene and a hydrophilic N-doped section synthetized from acetonitrile) revealed catalytic activity for the removal of 2-NP. The conversion of 2NP reached in biphasic oxidation conditions was 76.7% after 24 h of reaction at 50 °C, considering pH0 = 3, Ccat = 2.27 g L¿1 of total volume (water/oil ratio of 16:50 v/v) and C2-NP,oil,0 = 5 g L¿1. This removal was ascribed to the formation of Pickering emulsions, by maximizing the interfacial area through an increased contact between the catalyst and both liquid phases. A kinetic model is proposed to accurately predict the experimental data and evaluate the rate constants of the process and its variation with the prepared CNTs. © 2019 Elsevier B.V.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11