Chelating resins. III. Synthesis, characterization, and capacity studies of formaldehyde-condensed phenolic schiff bases derived from 1,2-diamines and hydroxy benzaldehydes

✍ Scribed by S. Samal; R. R. Das; D. Sahoo; S. Acharya; R. L. Panda; R. C. Rout

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 564 KB
• Volume: 62
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19961128)62:9<1437::aid-app13>3.0.co;2-w

✦ Synopsis

Schiff bases of hydroxy benzaldehydes with aliphatic and aromatic 1,2-diamines were resinified in HCHO in alkaline media. These resins were found to form complexes readily with Cu(II), Co(II), and Ni(I1). The materials were characterized by infrared, 'H-NMR, UV-visible (UV-vis) spectral studies, and thermogravimetric analyses. The phenolic oxygen and the azomethene nitrogen were the ligating sites, one or more lattice positions in polychelates being occupied by water molecules. 'H-NMR provided evidence for bridging methylene and terminal methylol groups. The UV-vis spectra showed weak absorptions in the d-d transition range. Capacity studies of the resins indicated metal loading up to 70% at room temperature in an appropriate pH of the salt solutions. The effects of contact time, particle size of the sorbents, resin quantity, and pH on the adsorption characteristics were studied. In the pH range 3-8, the resins derived from the structurally rigid Schiff bases exhibited higher capacity for the metal ions than the resins derived from structurally flexible Schiff bases. Kinetic parameters computed from the thermogravimetric data indicated the resins to be more stable than the corresponding polychelates.