Chemical immobilization of metals and metalloids by phosphates

• Fixation forms insoluble and non-bioavailable salts from metal and phosphate.
• The main focus has been on fixation of Pb and the formation of pyromorphite.
• Other metals and metalloids show potential for effective fixation by phosphate.

Remediation of metal contaminated media using orthophosphate fixation forms insoluble and non-bioavailable salts from metal and phosphate sources. The main focus has been on fixation of Pb, where the formation of pyromorphite, the most insoluble lead phosphate, has shown the great potential of this remediation technique. Other metals (Ba, Cd, Co, Cu, Eu, Ni, U, Zn) also have potential for effective fixation by orthophosphate. We review the applicability of the treatment across wider environmental conditions, particularly in surface soil, its use with elements other than Pb, product stability and efficiency with mixed contaminants.