THE CHARACTERIZATION AND THE SYNTHESIS OF A NEW COORDINATION COMPOUND FOR REMOVAL OF Cr(III) FROM WASTEWATERS

Abstract

The Schiff base N,N'-(salicylidene)-methylenediamine, known as Salmen in combination with Cr(III) forms at pH = 4.5 a greenish precipitate, which is stable at room temperature but decomposed on heating. The study of the Infrared spectra, Electron Spin Resonance (ESR), X-ray diffraction and thermogravimetry has pointed out that the precipitation form is a complex, while the molar ratio showed that the combination rate of Cr(III): N,N'-bis(salicylidene)-methylenediamine is 1:1. The new complex crystallizes in the triclinic systems. This precipitation reaction can be used as a method for the gravimetric determination of Cr(III) with N,N'-bis(salicylidene)-methylenediamine, known as Salmen The precipitate was dried in vacuum and weighed as C 15 H 13 O 3 N 2 Cr. The overage relative error is ± 0.33%. Salmen can be used in order to precipitate and to recover the chromium from wastewaters consequential to the tanning of natural fells.

Selective Formation, Reactivity, Redox and Magnetic Properties of MnIII and FeIII Dinuclear Complexes with Shortened Salen-Type Schiff Base Ligands

“…With the exception of H 3 salmp, for which quite a few complexes have been synthesized and structurally characterized up to date [ 10 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], less is known about the other two classes of shortened Schiff base derivatives [ 7 , 11 , 19 , 20 , 31 ]. Nevertheless, it is undeniable the usefulness of all these ligands for the synthesis of efficient catalysts [ 15 , 16 , 17 ], their use for metal sequestration in solution [ 32 ], synthesis of biomimetic systems [ 24 ] and the fascinating magnetic properties of the corresponding oligonuclear clusters [ 19 , 20 , 23 , 24 , 26 , 27 , 28 , 31 , 33 ]. Within this last topic, at the beginning of the new Millennium we started a systematic study on the coordination ability of H 2 salmen and H 2 salben with divalent metal ions [ 11 ] like copper(II) [ 19 ] and cobalt(II) [ 20 , 31 ], and the possibility to oxidize the latter to cobalt(III) and additionally form mixed-valence oligonuclear clusters [ 20 , 31 ].…”