Iron humate as a low-cost sorbent for metal ions.

Iron humate produced as a waste by-product during an industrial manufacture of humic substances from low-rank brown coals was tested as a sorbent for the removal of metal cations--Cd (II), Cu (II), Co (II), Ni (II), Zn (II), TI (I), Eu (III), Cr (III)--as well as hexavalent chromium from waters. The Langmuir-type isotherms were used to describe the metal sorption; the respective equations may be derived and interpreted on the basis of a concept of surface-complexation reactions. Parameters of the sorption isotherms were estimated from experimental dependencies measured in a batch arrangement.