Strontium/strontium-90 removal from chelate-bearing Hanford tank waste using crystalline silicotitanate

A study was conducted to evaluate if crystalline silicotitanate (CST) could be used to remove Sr-90 from highly chelated tank waste in support of tank waste immobilization. CST was shown to remove cesium from a high-complexant tank waste, AN-102 diluted to 5.7 M sodium ions (Na+), comparing well with an existing adsorption isotherm generated with a simplified simulant without chelates. Strontium, barium, and lead were also shown to partially exchange onto the CST, despite their expected chelation and without impacting cesium uptake. The moles of lead loaded onto CST were essentially equivalent to that of cesium. Increasing CST mass resulted in increasing strontium (barium and lead) uptake. Calcium was shown to not exchange, demonstrating strong calcium chelation, not amenable to exchange onto CST.

Automated summary

A study evaluated the use of crystalline silicotitanate (CST) for removing Sr-90 from tank waste in support of waste immobilization. The results showed that CST effectively removed cesium from chelated tank waste and also had partial exchange with strontium, barium, and lead. However, calcium demonstrated strong chelation and could not be exchanged onto CST.