Solar Light-Induced Methylene Blue Removal over TiO2/AC Composites and Photocatalytic Regeneration

TiO2-containing photocatalysts, which combine TiO2 with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO2/AC composites were pr...

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Autores principales:	Fernanda Dalto, Iwona Kuźniarska-Biernacka, Clara Pereira, Elsa Mesquita, Olívia Salomé G. P. Soares, M. Fernando R. Pereira, Maria João Rosa, Ana S. Mestre, Ana P. Carvalho, Cristina Freire
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	titanium dioxide activated carbon nanocomposite methylene blue adsorption solar-light induced photocatalysis Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/7154b5e2df6440ab9ca3d12e09090b5a
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spelling	oai:doaj.org-article:7154b5e2df6440ab9ca3d12e09090b5a2021-11-25T18:31:45ZSolar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration10.3390/nano111130162079-4991https://doaj.org/article/7154b5e2df6440ab9ca3d12e09090b5a2021-11-01T00:00:00Zhttps://www.mdpi.com/2079-4991/11/11/3016https://doaj.org/toc/2079-4991TiO<sub>2</sub>-containing photocatalysts, which combine TiO<sub>2</sub> with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO<sub>2</sub>/AC composites were produced by the in situ immobilization of TiO<sub>2</sub> nanoparticles over activated carbon (AC) derived from spent coffee grains, using different TiO<sub>2</sub>/AC proportions. The TiO<sub>2</sub>/AC composites were tested as adsorbents (dark) and as photocatalysts in a combined adsorption+photocatalytic process (solar irradiation) for methylene blue (MB) removal from ultrapure water, and from a secondary effluent (SecEf) of an urban wastewater treatment plant. All the materials were characterized by XRD (X-ray powder diffraction), N<sub>2</sub> adsorption–desorption isotherms at −196 °C, SEM (scanning electron microscopy), UV-Vis diffuse reflectance, FTIR (Fourier-transform infrared spectroscopy), TPD (temperature programmed desorption), XPS (X-ray photoelectron spectroscopy) and TGA (thermogravimetric analysis). The TiAC60 (60% C) composite presented the lowest band gap (1.84 eV), while, for TiAC29 (29% C), the value was close to that of bare TiO<sub>2</sub> (3.18 vs. 3.17 eV). Regardless of the material, the solar irradiation improved the percentage of MB discolouration when compared to adsorption in dark conditions. In the case of simultaneous adsorption+photocatalytic assays performed in ultrapure water, TiAC29 presented the fastest MB removal. Nevertheless, both TiAC29 and TiAC60 led to excellent MB removal percentages (96.1–98.1%). UV-induced photoregeneration was a promising strategy to recover the adsorption capacity of the materials, especially for TiAC60 and AC (>95%). When the assays were performed in SecEf, all the materials promoted discolouration percentages close to those obtained in ultrapure water. The bulk water parameters revealed that TiAC60 allowed the removal of a higher amount of MB, associated with the overall improvement of the SecEf quality.Fernanda DaltoIwona Kuźniarska-BiernackaClara PereiraElsa MesquitaOlívia Salomé G. P. SoaresM. Fernando R. PereiraMaria João RosaAna S. MestreAna P. CarvalhoCristina FreireMDPI AGarticletitanium dioxideactivated carbonnanocompositemethylene blueadsorptionsolar-light induced photocatalysisChemistryQD1-999ENNanomaterials, Vol 11, Iss 3016, p 3016 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	titanium dioxide activated carbon nanocomposite methylene blue adsorption solar-light induced photocatalysis Chemistry QD1-999
spellingShingle	titanium dioxide activated carbon nanocomposite methylene blue adsorption solar-light induced photocatalysis Chemistry QD1-999 Fernanda Dalto Iwona Kuźniarska-Biernacka Clara Pereira Elsa Mesquita Olívia Salomé G. P. Soares M. Fernando R. Pereira Maria João Rosa Ana S. Mestre Ana P. Carvalho Cristina Freire Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
description	TiO<sub>2</sub>-containing photocatalysts, which combine TiO<sub>2</sub> with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO<sub>2</sub>/AC composites were produced by the in situ immobilization of TiO<sub>2</sub> nanoparticles over activated carbon (AC) derived from spent coffee grains, using different TiO<sub>2</sub>/AC proportions. The TiO<sub>2</sub>/AC composites were tested as adsorbents (dark) and as photocatalysts in a combined adsorption+photocatalytic process (solar irradiation) for methylene blue (MB) removal from ultrapure water, and from a secondary effluent (SecEf) of an urban wastewater treatment plant. All the materials were characterized by XRD (X-ray powder diffraction), N<sub>2</sub> adsorption–desorption isotherms at −196 °C, SEM (scanning electron microscopy), UV-Vis diffuse reflectance, FTIR (Fourier-transform infrared spectroscopy), TPD (temperature programmed desorption), XPS (X-ray photoelectron spectroscopy) and TGA (thermogravimetric analysis). The TiAC60 (60% C) composite presented the lowest band gap (1.84 eV), while, for TiAC29 (29% C), the value was close to that of bare TiO<sub>2</sub> (3.18 vs. 3.17 eV). Regardless of the material, the solar irradiation improved the percentage of MB discolouration when compared to adsorption in dark conditions. In the case of simultaneous adsorption+photocatalytic assays performed in ultrapure water, TiAC29 presented the fastest MB removal. Nevertheless, both TiAC29 and TiAC60 led to excellent MB removal percentages (96.1–98.1%). UV-induced photoregeneration was a promising strategy to recover the adsorption capacity of the materials, especially for TiAC60 and AC (>95%). When the assays were performed in SecEf, all the materials promoted discolouration percentages close to those obtained in ultrapure water. The bulk water parameters revealed that TiAC60 allowed the removal of a higher amount of MB, associated with the overall improvement of the SecEf quality.
format	article
author	Fernanda Dalto Iwona Kuźniarska-Biernacka Clara Pereira Elsa Mesquita Olívia Salomé G. P. Soares M. Fernando R. Pereira Maria João Rosa Ana S. Mestre Ana P. Carvalho Cristina Freire
author_facet	Fernanda Dalto Iwona Kuźniarska-Biernacka Clara Pereira Elsa Mesquita Olívia Salomé G. P. Soares M. Fernando R. Pereira Maria João Rosa Ana S. Mestre Ana P. Carvalho Cristina Freire
author_sort	Fernanda Dalto
title	Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
title_short	Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
title_full	Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
title_fullStr	Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
title_full_unstemmed	Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration
title_sort	solar light-induced methylene blue removal over tio<sub>2</sub>/ac composites and photocatalytic regeneration
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/7154b5e2df6440ab9ca3d12e09090b5a
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Solar Light-Induced Methylene Blue Removal over TiO<sub>2</sub>/AC Composites and Photocatalytic Regeneration

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