Other Binders - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 103

TABLE 6.1.2 (CONTINUED)
Selected Treatment Studies for Heavy Metals and Radionuclides Using
Phosphates; Includes Laboratory Studies, Field Trials, and Applications

Metal/
Metalloid
Studied

Media/
Conditions

Phosphate
Treatment

Mechanism/Solid
Phases Formed References

Cd, Cu,
Pb, Zn

Municipal solid
waste combustion
dry scrubber
residue; pH 12

Phosphoric acid Formation of apatite,

tertiary metal phosphates,
and calcium phosphates
with incorporated metals

15

Cd, Pb, U Aqueous solution Synthetic

hydroxyapatite

Amorphous uranium phase
formed; formation of
hydroxypyromorphite and
lead oxide; possible
substitution of Pb for Ca;
Cd reported substitution
for Ca

39

Cd, Pb, Zn Aqueous solution;

pH range 1 to 12

North Carolina
mineral apatite

Hydrocerussite
(Pb 3 (CO 3 ) 2 (OH) 2 ) and
lead oxide fluoride
(Pb 2 OF 2 ) formed under
alkaline conditions and
pyromorphites under
acidic condition; otavite
(CdCO 3 ) calcium
hydroxide (Cd(OH) 2 ), and
zinc oxide (ZnO) in
alkaline conditions

40

Cd, Pb, Zn Soils and mine

tailings; pH 5.5 to
8

Calcium
oxyphosphate

Not determined 41

Cd, Se Aqueous solution Synthetic

hydroxyapatite

Penetration in the intra-
particle porosity
generated by aggregation
of Cd and Se crystals

42

Cd, Zn Aqueous solution;

pH 5.5 to 7.5

Synthetic
hydroxyapatite

Sorption by metal
complexation with surface
functional groups and
coprecipitation

43

Cr, Mn Aqueous solution Apatite from

thermally
treated fish
bone

Not determined 44a, 44b

(continued)