Environmental impact of amino acids on selenate-bearing hydrocalumite: Experimental and DFT studies

Selenium (Se) radioactive wastes can be disposed through stabilization/solidification (S/S) based on the cementitious matrix hydration products, where hydrocalumite (Ca2Al-LDH) is expected to play an important role in retention of SeO42−. Natural organic matters (NOMs) are known a risk affect transportation and mobility undesirable chemical species pedosphere which receives low level (LLW). In present work, five amino acids were selected as simplified models NOMs explore their effects stability Ca2Al-LDH after immobilized SeO42− under alkaline conditions. As loading amount increasing, release was enhanced HGly, H2Asp, H2Cys series, while no enhancement observed HPhe HTrp series. Density functional theory (DFT) calculation predicted ion-exchange CO32− with unit cell LDH model. The intercalation Asp2− caused 003 peaks XRD sharper d003 decreased from 8.15 Å 7.70 assigned Ca2Al-LDH(Asp, CO3). kept broad still relatively maintained by lower amounts intercalated presence H2Cys. Amino interlayer have several possible configurations, most stable one prone horizontal direction hydrogen bonds Ca–O bonds. This provides insight selenate hydrocalumite, produced cement disposing for long term burying. Not only carbonate but also small molecular like possibly give environmental impact anionic radionuclides LDH.