Effective and selective electrocatalyst for nitrate reduction based on multi walled carbon nanotube, Journal of Environmental Management 2021
Publication Type
Original research
Authors

Drinking-water contamination with nitrate ions is inevitable and wide spreading, which demands feasible removal. Water de-nitration by potentiostatic electroreduction is described here.  A novel electrocatalyst based on nano-copper particles, supported onto multi-walled carbon nanotubes (MWCNTs), and spray-deposited onto fluorine doped tin oxide-glass substrates, is described. The Cu/MWCNT/FTO electrode has been characterized by several methods and assessed as a working electrode in aqueous nitrate ion electroreduction, in comparison with MWCNT sprayed on FTO (MWCNT/FTO) with no copper.  Comparison with earlier reported electrodes is also described. XRD patterns confirm the presence of nano-copper crystallites, in the electrode, with average size ⁓45 nm. Within 2 h of electrolysis, Cu/MWVNT/FTO exhibits more than 65% removal of nitrate at -1.80 V (vs. SCE).  In longer time (7 h) the electrode completely converts the nitrate into N2 (~65%) and (NH4+) ~35% with no NO2- ions.  The kinetics show 0.76 order with respect to nitrate, and a rate constant 4.53×10-2 min-1 higher than earlier counterparts. The new electrode functions under various conditions of temperature, pH, electrolyte type and concentration and inter-electrode spacing, only at ambient applied potential. Moreover, the electrode exhibits stability under nitrate electroreduction conditions, and can be recovered and reused for multiple times without efficiency loss. XRD and EDS results also confirm the electrode stability after multiple reuse. Compared to earlier systems, the Cu/MWCNT/FTO is environmentally stable, safe, non-costly with high nitrate removal efficiency and selectivity.

Journal
Title
Journal of Environmental Management
Publisher
Elsevier
Publisher Country
Netherlands
Indexing
Thomson Reuters
Impact Factor
6.7
Publication Type
Both (Printed and Online)
Volume
305
Year
2022
Pages
114420