Surface complexation of neptunium(V) onto whole cells and cell components of shewanella alga: Modeling and experimental study

บทความในวารสาร

ผู้เขียน/บรรณาธิการ

วรินธร สงคศิริ

กลุ่มสาขาการวิจัยเชิงกลยุทธ์

ไม่พบข้อมูลที่เกี่ยวข้อง

รายละเอียดสำหรับงานพิมพ์

รายชื่อผู้แต่ง: Deo R.P., Songkasiri W., Rittmann B.E., Reed D.T.

ผู้เผยแพร่: American Chemical Society

ปีที่เผยแพร่ (ค.ศ.): 2010

วารสาร: Environmental Science and Technology (0013-936X)

Volume number: 44

Issue number: 13

หน้าแรก: 4930

หน้าสุดท้าย: 4935

จำนวนหน้า: 6

นอก: 0013-936X

eISSN: 1520-5851

URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-77954270268&doi=10.1021%2fes9035336&partnerID=40&md5=49acebf7a71445d5e1b7659859fe89ad

ภาษา: English-Great Britain (EN-GB)

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บทคัดย่อ

We systematically quantified surface complexation of Np(V) onto whole cells, cell wall, and extracellular polymeric substances (EPS) of Shewanella alga strain BrY. We first performed acid and base titrations and used the mathematical model FITEQL to estimate the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl group not associated with amino acids (pK a ∼ 5), a phosphoryl site (pKa ∼ 7.2), and an amine site (pKa > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components as a function of pH. Since significant Np(V) sorption was observed on S. alga whole cells and its components in the pH range 2-5, we assumed the existence of a fourth site: a low-pKa carboxyl site (pKa ∼ 2.4) that is associated with amino acids. We used the SPECIATE submodel of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, the aquo NpO2 + species was the dominant form of Np(V), and its log K values for the low-pKa carboxyl, mid-pKa carboxyl, and phosphoryl groups were 1.8, 1.8, and 2.5-3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH3+, which complexed with NpO2(CO3)35-. The log K for NpO 2(CO3)35- complexed onto the amine groups was 3.1-3.9. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results help quantify the role of surface complexation in defining actinide- microbiological interactions in the subsurface. © 2010 American Chemical Society.

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