The Hydrolytic Stability and Degradation Mechanism of a Hierarchically Porous Metal Alkylphosphonate Framework

Abstract

To aid the design of a hierarchically porous unconventional metal-phosphonate framework (HP-UMPF) for practical radioanalytical separation, a systematic investigation of the hydrolytic stability of bulk phase against acidic corrosion has been carried out for an archetypical HP-UMPF. Bulk dissolution results suggest that aqueous acidity has a more paramount effect on incongruent leaching than the temperature, and the kinetic stability reaches equilibrium by way of an accumulation of a partial leached species on the corrosion conduits. A variation of particle morphology, hierarchical porosity and backbone composition upon corrosion reveals that they are hydrolytically resilient without suffering any great degradation of porous texture, although large aggregates crack into sporadic fractures while the nucleophilic attack of inorganic layers cause the leaching of tin and phosphorus. The remaining selectivity of these HP-UMPFs is dictated by a balance between the elimination of free phosphonate and the exposure of confined phosphonates, thus allowing a real-time tailor of radionuclide sequestration. Moreover, a plausible degradation mechanism has been proposed for the triple progressive dissolution of three-level hierarchical porous structures to elucidate resultant reactivity. These HP-UMPFs are compared with benchmark metal-organic frameworks (MOFs) to obtain a rough grading of hydrolytic stability and two feasible approaches are suggested for enhancing their hydrolytic stability that are intended for real-life separation protocols.

Combined Experimental and Theoretical Insights into the Corrosion Inhibition Activity on Carbon Steel Iron of Phosphonic Acids

“…Corrosion inhibition efficiency correlates with the structure of phosphonate-based molecules [ 15 , 16 , 17 ]. Kálmán and coworkers studied the corrosion inhibition for a low-concentration of 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and high concentration of HEDP on neutral carbon steel.…”

Crystalline versus Amorphous: High-Performance Hafnium Phosphonate Framework for the Separation of Uranium and Transuranium Elements

“…Besides, actinide-laden MPFs can be exploited as a stable primary waste form without an energy-consuming conversion to metal phosphate or oxide waste forms before final disposal . Heretofore, the alkyl-phosphonate-based MPFs have demonstrated potential in radioanalytical separation − and nuclear wastewater treatment, − while the aryl-phosphonate-based MPFs were utilized to remove lanthanides and actinides from acidic solutions. − …”