Cavitation-assisted decontamination of yttria from graphite of different densities

Abstract

Highlights Intensified reprocessing of graphite based on dissolution of yttrium. Understanding into effect of operating conditions on process efficiency. Effect of adding oxidant, H2O2, to the leachant acid on the decontamination rate. Weight gain of the graphite substrate due to oxidation, despite surface erosion due to cavitation. Kinetic study for dissolution of yttrium from graphite of different densities (and pore size distribution).

Sonochemical recovery of uranium from nanosilica-based sorbent and its biohybrid

“…Based on the obtained results, the recommended operating frequency for SiO 2 M is 20 kHz. Similar trend was also reported for the case of uranium and yttria recovery from graphite substrate [32] , [39] .…”

“…When a cavitation bubble collapses, microjets of the solvent impinging on the surface lead to cleaning or dislodging of adsorbed metal. An increase in the resultant microstreaming further increases the mass transfer across the boundary layer as well as possibly thinning of the film and effective desorption is obtained as also reported for nuclear materials [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] .…”

“…2 (b) respectively. Nitric acid is widely used for uranium recovery [39] . The extent of dissolution of uranium with 8 M nitric acid at the operating temperature 45 °C was less than 6% and 20% in 1 h for both SiO 2 M and f BHM respectively in the absence of ultrasonic field.…”

“…2 (f) for the case of 16 M acid strength. Even in the case of U recovery from graphite, too high acid strength was observed to lead to pitting corrosion of the substrate [32] , [39] . Therefore, though the leaching of uranium from SiO 2 M would be fastest in 16 M acid but due to the damage to the structure of SiO 2 M, high release of NO x gases from the dissolution process and stringent requirement on the material of construction for the ultrasonic bath, very high concentration of acid is considered to be difficult to handle on a large scale.…”

Sonocatalytic recovery of ceria from graphite and inhibition of graphite erosion by ionic liquid based platinum nanocatalyst

“…Cavitation is the growth and implosion of micro-bubbles generated due to ultrasound. In a heterogeneous system, the impact of the implosion on solid surface is an effective tool to dislodge contaminants and deposits from the surface or the pores [4] , [5] . The high temperatures and pressures generated inside the bubbles also leads to radical formation that further accelerates the reaction pathway.…”