Molten carbamide

The fifth paper in this chapter is by S. Kochetova and N. Tumanova of the National Academy of Sciences of Ukraine. It addresses subjects of electrolysis of molten carbamides. Authors report on interesting results of their study of the mechanisms of reactions occurring in the carbamide and carbamide-chloride melts using techniques of cyclic voltammetry in combination with gas chromatography and IR spectroscopy. 

Molten carbamide is known to be a good solvent for the salts of many metals [1] and was used as a supporting electrolyte in polarographic investigations both at a dropping mercury electrode and at a stationary... 

In order to determine the electrochemical properties of the solvent, the electrode process in molten carbamide and in carbamide-MeCl (where Me - NH4, K) mixtures on inert electrodes (platinum, glassy carbon) were investigated using cyclic voltammetry. The electrode reaction products were analysed by spectroscopic methods. The adsorbtion of carbamide- NH4CI anodic product was investigated by differential capacity method. 

In an individual molten carbamide, the electrode processes are feebly marked at melt decomposition potentials (Fig. 1) because of its low electrical conductivity. Both electrode processes are accompanied by gas evolution. 

Figure 1. Cyclic voltamperogram ofPt (1) and glassy carbon (2) electrodes in molten carbamide.

In an individual molten carbamide, the electrode processes are feebly marked at melt decomposition potentials because of its low electrical conductivity. Both electrode processes are accompanied by gas evolution (NH3, CO, C02, N2) and NH2CN (approximately) is formed in melt. In eutectic carbamide-chloride melts electrode processes take place mainly independently of each other. The chlorine must evolve at the anode during the electrolysis of carbamide - alkali metal and ammonium chloride melts, which were revealed in the electrolysis of the carbamide-KCl melt. But in the case of simultaneous oxidation of carbamide and NH4CI, however, a new compound containing N-Cl bond has been found in anode gases instead of chlorine. It is difficult to fully identify this compound by the experimental methods employed in the present work, but it can be definitely stated that... 

Use of low-temperature molten systems for electrolytic processes related with tantalum and niobium and other rare refractory metals seems to hold a promise for future industrial use, and is currently of great concern to researchers. The electrochemical behavior of tantalum, niobium and titanium in low-temperature carbamide-hilide melts has been investigated by Tumanova et al. [572]. Electrodeposition of tantalum and niobium from room/ambient temperature chloroaluminate molten systems has been studied by Cheek et al. [573],... 

Electrolysis cyclic voltammetry molten salts carbamide potassium chloride ammonium chloride compound adsorbtion. 

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