caa a22 4500 378881922 CHVBK 20180305123434.0 cr unu---uuuuu 161128e20030301xx s 000 0 eng 10.1524/ract.91.3.173.19977 doi (NATIONALLICENCE)gruyter-10.1524/ract.91.3.173.19977 Kaplan D. I. Influence of surface charge of an Fe-oxide and an organic matter dominated soil on iodide and pertechnetate sorption [Elektronische Daten] [D. I. Kaplan] Iodine-129 and technecium-99 are commonly the largest contributors to the calculated health risk associated with long-term nuclear-waste burial. The high proportion of risk from these radionuclides is due to their large inventories in many types of waste, long half-lives, and the perception that they are highly mobile in sediments. In most aquifer systems, these radionuclides exist as anions, iodide (I-) and pertechnetate (TcO4-), and sorb poorly to soils that possess a net negative charge. A series of iodide and pertechnetate sorption experiments were conducted over a pH range of 3 to 9. The two soils used in this study possessed a pH-dependent charge; one soil was collected from a wetland and derived most of its charge from organic matter, whereas the second soil was collected from an upland site and derived most of its charge from Fe/Al-oxide coatings. Although both soils had nearly identical particle size distributions, pH values, and mineral compositions, they had dissimilar surface charge and I- and TcO4- sorption behavior. The pH where the wetland soil did not have any net charge (more specifically, the Point-of-Zero-Salt Effect) was 4.4. The pH where the upland soil did not have any net charge was 4.1. Under ambient conditions, the wetland soil had a pH of 4.2 and a slight positive net charge of +0.1meq/100g. The upland soil had a natural pH of 5.0 and a net charge of -0.25meq/100g. Both iodide and pertechnetate sorbed appreciably more to the wetland soil than to the upland soil, likely the result of more anion sorption sites derived from the organic matter in the wetland soil. In both soils, iodide sorption was greater and exhibited a greater pH-dependency than pertechnetate sorption. Pertechnetate exhibited anion exclusion (negative Kd values) or no sorption at pH values above the Point-of-Zero-Salt Effect. Iodide sorption decreased markedly as the pH increased to the zero-point-of-charge, and remained largely unchanged at pH values above the zero-point-of-charge. © 2003 Oldenbourg Wissenschaftsverlag GmbH Laboratory techniques, experiments nationallicence Analytical chemistry nationallicence Inorganic chemistry nationallicence Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/3/2003(2003-03-01), 173-178 0033-8230 91:3/2003<173 2003 91 ract https://doi.org/10.1524/ract.91.3.173.19977 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/ract.91.3.173.19977 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Kaplan D. I. NATIONALLICENCE 773 0- Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/3/2003(2003-03-01), 173-178 0033-8230 91:3/2003<173 2003 91 ract CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter