Treatment given

Cd

Pb

Fe

Cu

Ni

Cr⁶⁺

Reference

None

65

48

[47]

None

43^a

[48]

Na₂S

81

[49]

None

10^a

[50]

None

55^b

[51]

None

18^b

[52]

None

11

9

[53]

Acid washed

79

27

[54]

None

14

26

12

This work