Copper Sorption on a Straw Lignin: Experiments and EPR Characterization

✍ Scribed by Patricia Merdy; Emmanuel Guillon; Michel Aplincourt; Jacques Dumonceau; Hervé Vezin

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 116 KB
• Volume: 245
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.7972

✦ Synopsis

Spectroscopic and physicochemical data, X-ray photoelectron spectroscopy (XPS), solid-state (13)C cross-polarization magic-angle-spinning NMR, GC/MS, specific surface area, site density, and surface acidity constants have been recorded or determined for a ligno-cellulosic substrate (LS) extracted from straw. Its copper(II)-bound ability has also been studied. The LS solid that exhibits two types of binding sites, carboxylic and phenolic groups, has a great affinity for copper(II), with a maximum of adsorption at around 4 mg g(-1) as early as the pH reaches 6. The structural characterization of the Cu(II) surface complexes has been investigated using EPR spectroscopy. The CuO(4) chromophore of the inner-sphere surface complexes is a slightly distorted square. A surface oxidation occurred simultaneously, which leads to semiquinonic radicals. Furthermore, our empirical approach, which used a correlation between thermodynamics data and EPR parameters, has led to a surface complexation constant log beta equal to 12.6. This indicates that copper(II) surface complexes are relatively stable.