Mechanistic analysis of photocatalytic transformation of naphthalene using a nano-O-doped-g-C3N4-CuO n-p heterojunction

resumo

Conventional photocatalysts suffer from inefficient charge separation and rapid recombination rate of the electron-hole pairs. The motivation of the present study is, hence, to develop a composite of CuO nanoparticles and O-doped-g-C3N4 (CN) to address the mentioned issues for the efficient removal of naphthalene (NAP), one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in aquatic media. The nanoparticles were characterised by XRD, STEM, EDS, gas adsorption (BET isotherm), XPS, FTIR and band gap analysis. Mott-Schottky studies were performed to understand the formation of the heterojunction in the O-doped-g-C3N4-CuO (OGC) photocatalyst. The prepared n-p-type heterostructure nanocomposite with a tuned band gap energy (1.55 eV, compared to 2.49 eV for CN and 1.79 for CuO) offered efficient removal of NAP by promoting the generation and separation of electron-hole pairs. The optimisation indicated the best performance (87.1 % of 20 mg of NAP) of the system using OGC (0.25 g/L) at pH 6 under visible light irradiation in 60 min. The removal rate of NAP was studied by pseudo-first-order reaction rate kinetics in addition to mechanistic studies on the NAP degradation pathways using quenching tests, electron paramagnetic resonance (EPR) measurements, and gas chromatography-mass spectrometry (GC-MS). According to the results achieved, OGC is an efficient heterojunction for the degradation of NAP under visible light irradiation by producing both center dot O2- and center dot OH radicals. Such an efficient process can significantly aid in enhancing the quality of the polluted waters and protection of the environment.

palavras-chave

LIGHT-INDUCED PHOTODEGRADATION; FACILE SYNTHESIS; DEGRADATION; ADSORPTION; REMOVAL; WATER; CIPROFLOXACIN; PHENANTHRENE; POLLUTANTS

categoria

Engineering

autores

Khalaj, M; Kamali, M; Estrada, AC; Rasekh, S; Trindade, T; Aminabhavi, TM; Sobolev, NA; Costa, MEV; Dewil, R; Capela, I

Grupos

G1 - Materiais Porosos e Nanossistemas
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos

Projectos

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

agradecimentos

Thanks are due for financial support to CESAM - Centre for Environmental and Marine Studies, POCI-01-0145-FEDER-007638 (FCT Ref. UID/AMB/50017/2020). This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC). Thanks, are also due to FCT for the doctoral scholarship No. SFRH/BD/140873/2018 for the first author. Ana C. Estrada thanks the costs of her research contract resulting from the FCT hiring funded by National funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in 4, 5, and 6 of article 23 of the Decree-Law 57/2016, of 29 August, changed by the law 57/2017, of 19 July. Dr. Sh. Rasekh also acknowledges the support of the Research Employment Contract FCT-CEECIND/02608/2017. JD acknowledges national funds from FCT-Fundacao para a Ciencia e a Tecnologia,I.P., within CEECINST/00102/2018, LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nano- structures, Nanomodelling, and Nanofabrication-i3N. N.A.S was 15 supported also by project i3N, UIDB/50025/2020 and UIDP/50025/2020, financed by national funds through the Fundacao para a Ciencia e Tecnologia (FCT) and the Ministerio da Educacao e Ciencia (MEC) of Portugal.r supported also by project i3N, UIDB/50025/2020 and UIDP/50025/2020, financed by national funds through the Fundacao para a Ciencia e Tecnologia (FCT) and the Ministerio da Educacao e Ciencia (MEC) of Portugal.