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Remediation of radioiodine using polyamine anion exchange resins
Daniel N.T. Barton,Thomas J. Robshaw,Oluwatobi Okusanya,김대근,Sarah E. Pepper,Clint A. Sharrad,이택승,Mark D. Ogden 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.78 No.-
Two weak base anion exchange resins, Lewatit A365 and Purolite MTS9850, have been tested for theremoval of aqueous iodide from conditions simulating nuclear waste reprocessing streams. pH variationand relevant co-contaminant addition (nitrate, molybdate and iodine) allowed for assessment of iodideextraction behaviour of each resin. Isotherm experiments were performed and maximum uptakecapacities obtained exceed current industrial adsorbents, such as silver-impregnated zeolites. Maximumloading capacities, determined by Dubinin–Radushkevich isotherm, were 76114 mg g 1 for MTS9850and 589 15 mg g 1 for A365. Uptake for both resins was significantly suppressed by nitrate andmolybdate ions. The presence of dissolved iodine in the raffinate however, was found to increase iodideuptake. This was explained by characterisation of the spent resin surface by infrared and Ramanspectroscopy, which determined the presence of triiodide, indicating charge-transfer complex formationon the surface. Dynamic studies assessed the effect of co-contaminants on iodide uptake in a columnenvironment. Data wasfitted to three dynamic models, with the Dose-Response model providing the bestdescription of breakthrough. In all cases iodide breakthrough was accelerated, indicating suppression ofuptake, but capacity was still significant.
Charlie R. Adams,Christopher P. Porter,Thomas J. Robshaw,James P. Bezzina,Victoria R. Shields,Alan Hides,Richard Bruce,Mark D. Ogden 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-
This study reports the development of a hydrometallurgical treatment for activated carbon ash (ACA); awaste product of the carbon-in-pulp (CIP) process used in the gold mining industry, rich in adsorbedprecious metals. After an initial screening of known leaching chemistries, the research focusses on duallixiviant(thiourea and thiocyanate) and thiourea systems, both of which have lower environmentalimpact than traditional cyanide leaches. Comparing ferric sulfate and hydrogen peroxide as oxidantsshowed that a thiourea leach is more suited to ferric sulfate whereas the dual-lixiviant leach achievedgreater extraction with hydrogen peroxide. This was believed to be due to a more favourable effective[thiourea]:[thiocyanate] molar ratio in solution. The latter demonstrated faster kinetics and improvedefficiency for dissolution of gold and silver. However, both leaches had issues with silver extraction due toformation of passivating layers on the surface of the silver nanoparticles. Kinetic modelling showed bothsystems tended towards a mixed-controlled process. Gold extraction of 89%, with leaching reachingequilibrium within 100 min, using the dual-lixiviant process demonstrated that there is an alternative tocyanide leaches employed in gold recovery.