COPPER NANOPARTICLES ON CHEMICALLY PURE ALUMINUM AS NITRATE ELECTROREDUCTION CATALYST IN NATURALLY CONTAMINATED WATER

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Date
2023-08-28
Authors
Muna Saber Najeeb Sleem
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The contamination of water, particularly ground water, with nitrate ion is an increasing problem globally and locally, that results from extensive usage of nitrate-based fertilizers. That demands safe and practical solution to get rid of their risks on humans and the environment. Electrochemical reduction of nitrate is a good solution for this problem. Thus, this research aims to increase the conversion percent of nitrate and to increase the selectivity toward N2 production with minimal NH4+ or NO2-, especially for drinking water treatment. This is achieved by modification of a cheap, stable, and safe electrode with high conversion efficiency. The study investigated the possibility of electrochemically removing nitrate ions from naturally contaminated waters without addition of electrolyte. In this research, the electrochemical reduction of nitrate was studied under potentiostatic mode, in order to achieve lower power consumption in comparison with galvanostatic mode described in previous literature. The electrochemical reduction of nitrate in water was performed in a lab-scale undivided electrochemical cell. The cell involved three electrodes: a saturated calomel electrode (SCE) reference electrode, a platinum (Pt) sheet counter electrode, and the working electrode. The working electrode was a 2×(1×4) cm2 copper (Cu) modified electrode based on chemically pure aluminum (Al) sheet. Four electrodes were studied, namely: Al, Cu@Al, Gr@Al and, Cu@Gr/Al electrodes, where Gr is graphene. The electrodes were characterized by using X-ray diffraction (XRD), scanning-electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The different modified electrodes were then used for electrochemical reduction of nitrate from naturally contaminated water without adding electrolyte. Among the studied electrodes, the Cu@Al exhibited the highest percent of nitrate conversion (51.50% in 2 h) with the highest selectivity for N2 production at moderate temperature (20±1ºC), applied potential (-1.80 V), and neutral pH (7.02). Moreover, the kinetics for electrochemical reduction of nitrate by using Cu@Al electrode, studied using the method of initial rates, showed a reaction rate order 0.78 with a rate constant 1.07×10-4 sec-1 per 8 cm2 of electrode. Keywords: Al; Cu nanoparticles; Electrochemical reduction; Ground water; Nitrate.
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