Effects of freeze-thaw cycling on metal-phosphate formation and stability in single and multi-metal systems

Erla G. Hafsteinsdóttir*, Duanne A. White, Damian B. Gore

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)

    Abstract

    Freeze-thaw cycling may influence the chemistry, mineral stability and reaction rate during metal orthophosphate fixation. This study assessed the formation and stability of Cu-, Pb-, and Zn-phosphates in chemically simple laboratory systems during 240 freeze-thaw cycles (120 days) from +10 to -20 °C, using X-ray diffractometry. In single heavy metal systems, chloro- and hydroxy-pyromorphite (Pb5(PO4)3(Cl,OH)), sodalite (Na6Zn6(PO4)6· 8H2O), chiral zincophosphate (Na12(Zn12P 12O48)·12H2O), and copper phosphate hydrate (Cu3(PO4)2·3H2O) were the primary phosphate minerals that formed, and were typically stable during the experiment. Zinc and Cu-phosphate formation was reduced in multi heavy metal systems, and was substantially lower in abundance than chloropyromorphite. Successful Cu-, Pb- and Zn-phosphate formation can be expected in cold and freezing environments like the polar regions. However, field implementation of orthophosphate fixation needs to consider competing ion effects, concentration of the phosphate source, and the amount of free-water.

    Original languageEnglish
    Pages (from-to)168-177
    Number of pages10
    JournalEnvironmental Pollution
    Volume175
    DOIs
    Publication statusPublished - 2013

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