Catalytic and Photocatalytic Nitrate Reduction Over Pd-Cu Loaded Over Hybrid Materials of Multi-Walled Carbon Nanotubes and TiO2.

Cláudia G Silva,José J M Órfão,Joaquim L Faria,Manuel F R Pereira,Olívia S G P Soares

doi:10.3389/fchem.2018.00632

Cláudia G Silva, José J M Órfão + Show 3 more

Open Access

https://doi.org/10.3389/fchem.2018.00632

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Journal: Frontiers in chemistry	Publication Date: Dec 20, 2018
Citations: 23	License type: CC BY 4.0

Affiliation: University of Porto

Abstract

TiO2 and carbon nanotube-TiO2 hybrid materials synthesized by sol-gel and loaded with 1%Pd−1%Cu (%wt.) were tested in the catalytic and photocatalytic reduction of nitrate in water in the presence of CO2 (buffer) and H2 (reducing agent). Characterization of the catalysts was performed by UV-Vis and fluorescence spectroscopy, X-ray diffraction, temperature programed reduction, N2 adsorption, and electron microscopy. The presence of light produced a positive effect in the kinetics of nitrate removal. Higher selectivity toward nitrogen formation was observed under dark condition, while the photo-activated reactions showed higher selectivity for the production of ammonium. The hybrid catalyst containing 20 %wt. of carbon nanotubes shows the best compromise between activity and selectivity. A mechanism for the photocatalytic abatement of nitrate in water in the presence of the hybrid materials was proposed, based in the action of carbon nanotubes as light harvesters, dispersing media for TiO2 particles and as charge carrier facilitators.

Highlights

Nitrate is a naturally occurring ion that is part of the nitrogen cycle, in which nitrogen species are switched between organisms and the environment
In the present work we explored the synergies between carbon nanotubes (CNT) and titanium dioxide in both catalytic and photocatalytic reduction of nitrate in water
TiO2 and CNT-TiO2 loaded with 1%Pd−1%Cu show high catalytic activity in the dark and under near UV to visible light irradiation, in the presence of H2 and CO2

Summary

Introduction

Nitrate is a naturally occurring ion that is part of the nitrogen cycle, in which nitrogen species are switched between organisms and the environment. TiO2 and carbon nanotube-TiO2 hybrid materials synthesized by sol-gel and loaded with 1%Pd−1%Cu (%wt.) were tested in the catalytic and photocatalytic reduction of nitrate in water in the presence of CO2 (buffer) and H2 (reducing agent).

Results

Conclusion