Simultaneous photocatalytic removal of nitrate and oxalic acid over Cu2O/TiO2 and Cu2O/TiO2-AC composites

Haruna Adamu; Alan J. McCue; Rebecca S.F. Taylor; Haresh G. Manyar; James A. Anderson

doi:10.1016/j.apcatb.2017.05.091

Simultaneous photocatalytic removal of nitrate and oxalic acid over Cu₂O/TiO₂ and Cu₂O/TiO₂-AC composites

Haruna Adamu, Alan J. McCue, Rebecca S.F. Taylor, Haresh G. Manyar, James A. Anderson^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

94 Citations (Scopus)

16 Downloads (Pure)

Abstract

Cu₂O/TiO₂ (1–10 wt% Cu₂O) and 2.5% Cu₂O/TiO₂-AC (2.5–20 wt% AC) photocatalyst composites were synthesised by an ethanol reduction method. The materials were characterised by a number of techniques which confirmed the presence of Cu₂O in contact with the TiO₂. Pure TiO₂ alone was not active for the simultaneous photocatalytic removal of nitrate and oxalic acid under conditions employed, however, photocatalytic activity was observed for TiO₂ and TiO₂/AC in the presence of Cu₂O. This may have resulted from suppression of charge recombination via creation of a p-n heterojunction between Cu₂O and TiO₂. Within the series, 2.5% Cu₂O/TiO₂ exhibited the best photocatalytic performance with 57.6 and 99.8% removal of nitrate and oxalic acid, respectively, with selectivities of 45.7, 12.4 and 41.9% to NH₄ ⁺, NO₂ ⁻ and N₂, respectively after 3 h. For the carbon containing photocatalysts, 2.5% Cu₂O/TiO₂-2·5AC displayed the highest activity with 42.5 and 96.6% removal of nitrate and oxalic acid, respectively, with 32.7, 11.6 and 55.7% selectivities to NH₄ ⁺, NO₂ ⁻ and N₂, respectively. The highest AC loading tested resulted in selectivity to NH₄ ⁺ of 21.6 with no NO₂ ⁻ detected, together with an improved N₂ selectivity (78.4%) albeit at lower (12.7%) nitrate conversion. Data suggests that Cu₂O/TiO₂ can be used in the photocatalytic reduction of nitrate and improved selectivity towards N₂ can be attained by influencing factors which control the relative rate of oxalic acid consumption.

Original language	English
Pages (from-to)	181-191
Number of pages	11
Journal	Applied Catalysis B: Environmental
Volume	217
Early online date	3 Jun 2017
DOIs	https://doi.org/10.1016/j.apcatb.2017.05.091
Publication status	Published - 15 Nov 2017

Bibliographical note

This research supported by the Petroleum Technology Development Fund (PTDF) of Nigeria. We are grateful to Abubakar Tafawa Balewa University, Bauchi-Nigeria for the award of a studentship (to HA).

Keywords

Activated carbon
Composites
Nitrate
Oxalic acid
Photocatalysis
Titania

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Cite this

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title = "Simultaneous photocatalytic removal of nitrate and oxalic acid over Cu2O/TiO2 and Cu2O/TiO2-AC composites",

abstract = "Cu2O/TiO2 (1–10 wt% Cu2O) and 2.5% Cu2O/TiO2-AC (2.5–20 wt% AC) photocatalyst composites were synthesised by an ethanol reduction method. The materials were characterised by a number of techniques which confirmed the presence of Cu2O in contact with the TiO2. Pure TiO2 alone was not active for the simultaneous photocatalytic removal of nitrate and oxalic acid under conditions employed, however, photocatalytic activity was observed for TiO2 and TiO2/AC in the presence of Cu2O. This may have resulted from suppression of charge recombination via creation of a p-n heterojunction between Cu2O and TiO2. Within the series, 2.5% Cu2O/TiO2 exhibited the best photocatalytic performance with 57.6 and 99.8% removal of nitrate and oxalic acid, respectively, with selectivities of 45.7, 12.4 and 41.9% to NH4 +, NO2 − and N2, respectively after 3 h. For the carbon containing photocatalysts, 2.5% Cu2O/TiO2-2·5AC displayed the highest activity with 42.5 and 96.6% removal of nitrate and oxalic acid, respectively, with 32.7, 11.6 and 55.7% selectivities to NH4 +, NO2 − and N2, respectively. The highest AC loading tested resulted in selectivity to NH4 + of 21.6 with no NO2 − detected, together with an improved N2 selectivity (78.4%) albeit at lower (12.7%) nitrate conversion. Data suggests that Cu2O/TiO2 can be used in the photocatalytic reduction of nitrate and improved selectivity towards N2 can be attained by influencing factors which control the relative rate of oxalic acid consumption.",

keywords = "Activated carbon, Composites, Nitrate, Oxalic acid, Photocatalysis, Titania",

author = "Haruna Adamu and McCue, {Alan J.} and Taylor, {Rebecca S.F.} and Manyar, {Haresh G.} and Anderson, {James A.}",

note = "This research supported by the Petroleum Technology Development Fund (PTDF) of Nigeria. We are grateful to Abubakar Tafawa Balewa University, Bauchi-Nigeria for the award of a studentship (to HA).",

year = "2017",

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T1 - Simultaneous photocatalytic removal of nitrate and oxalic acid over Cu2O/TiO2 and Cu2O/TiO2-AC composites

AU - Adamu, Haruna

AU - McCue, Alan J.

AU - Taylor, Rebecca S.F.

AU - Manyar, Haresh G.

AU - Anderson, James A.

N1 - This research supported by the Petroleum Technology Development Fund (PTDF) of Nigeria. We are grateful to Abubakar Tafawa Balewa University, Bauchi-Nigeria for the award of a studentship (to HA).

PY - 2017/11/15

Y1 - 2017/11/15

N2 - Cu2O/TiO2 (1–10 wt% Cu2O) and 2.5% Cu2O/TiO2-AC (2.5–20 wt% AC) photocatalyst composites were synthesised by an ethanol reduction method. The materials were characterised by a number of techniques which confirmed the presence of Cu2O in contact with the TiO2. Pure TiO2 alone was not active for the simultaneous photocatalytic removal of nitrate and oxalic acid under conditions employed, however, photocatalytic activity was observed for TiO2 and TiO2/AC in the presence of Cu2O. This may have resulted from suppression of charge recombination via creation of a p-n heterojunction between Cu2O and TiO2. Within the series, 2.5% Cu2O/TiO2 exhibited the best photocatalytic performance with 57.6 and 99.8% removal of nitrate and oxalic acid, respectively, with selectivities of 45.7, 12.4 and 41.9% to NH4 +, NO2 − and N2, respectively after 3 h. For the carbon containing photocatalysts, 2.5% Cu2O/TiO2-2·5AC displayed the highest activity with 42.5 and 96.6% removal of nitrate and oxalic acid, respectively, with 32.7, 11.6 and 55.7% selectivities to NH4 +, NO2 − and N2, respectively. The highest AC loading tested resulted in selectivity to NH4 + of 21.6 with no NO2 − detected, together with an improved N2 selectivity (78.4%) albeit at lower (12.7%) nitrate conversion. Data suggests that Cu2O/TiO2 can be used in the photocatalytic reduction of nitrate and improved selectivity towards N2 can be attained by influencing factors which control the relative rate of oxalic acid consumption.

AB - Cu2O/TiO2 (1–10 wt% Cu2O) and 2.5% Cu2O/TiO2-AC (2.5–20 wt% AC) photocatalyst composites were synthesised by an ethanol reduction method. The materials were characterised by a number of techniques which confirmed the presence of Cu2O in contact with the TiO2. Pure TiO2 alone was not active for the simultaneous photocatalytic removal of nitrate and oxalic acid under conditions employed, however, photocatalytic activity was observed for TiO2 and TiO2/AC in the presence of Cu2O. This may have resulted from suppression of charge recombination via creation of a p-n heterojunction between Cu2O and TiO2. Within the series, 2.5% Cu2O/TiO2 exhibited the best photocatalytic performance with 57.6 and 99.8% removal of nitrate and oxalic acid, respectively, with selectivities of 45.7, 12.4 and 41.9% to NH4 +, NO2 − and N2, respectively after 3 h. For the carbon containing photocatalysts, 2.5% Cu2O/TiO2-2·5AC displayed the highest activity with 42.5 and 96.6% removal of nitrate and oxalic acid, respectively, with 32.7, 11.6 and 55.7% selectivities to NH4 +, NO2 − and N2, respectively. The highest AC loading tested resulted in selectivity to NH4 + of 21.6 with no NO2 − detected, together with an improved N2 selectivity (78.4%) albeit at lower (12.7%) nitrate conversion. Data suggests that Cu2O/TiO2 can be used in the photocatalytic reduction of nitrate and improved selectivity towards N2 can be attained by influencing factors which control the relative rate of oxalic acid consumption.

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