Use of analytical microscopy to analyze the speciation of copper and chromium ions onto a low-cost biomaterial

Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: A review

“…Characterization of lignocellulosic substrates has been performed by X-ray diffraction (XRD) [9,75], scanning electron microscopy (SEM) [9,40,43,49,103], scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) [44,73,75] and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM-EDX) [75,100].…”

“…The oxidation state of chromium bound on the biomaterial, the coordination geometry and the nature of the bond between the adsorbing atom and its ligands, was performed by X-ray photoelectron spectroscopy (XPS) [31,[49][50][51], X-ray absorption near-edge structure (XANES) [44,75,76], extended X-ray absorption fine structure spectroscopy (EXAFS) [31,75,76], electronic paramagnetic resonance or electronic spin resonance (EPR or ESR) [45,75] and by energy electron loss spectroscopy (EELS) [100].…”

“…IR and XPS spectroscopy were used to identify carboxylic and phenolic moieties as the main functional groups in the lignocellulosic substrate, and EXAFS spectroscopy to characterize the structure of the sorption complex formed on the biomaterial. Dupont et al [100] used transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDXS) to determine the speciation of Cr on the lignin entities of the lignocellulosic substrate. The use of a staining agent sensitive to unsaturation (OsO 4 ) allowed the differentiation between microstructures rich in lignin and rich in cellulose.…”

Determination of sorbent point zero charge: usefulness in sorption studies

“…Among the recent ones, some vegetable materials such as wheat bran (Dupont et al 2004), rice bran (Montanher et al 2005), algae and peat (Cochrane et al 2006) have been reported to present good capacity for copper sorption. In our laboratory, the removal of copper ions by using cork and yohimbe bark (Villaescusa et al 2000), grape stalks (Villaescusa et al 2004) and olive stones (Fiol et al 2006) have also been studied.…”

“…In literature, different mechanisms have been proposed for divalent metal sorption onto vegetable wastes: complexation reactions (Dupont et al 2004), ionic exchange (Gérente et al 2000;Villaescusa et al 2004) and microprecipitation (Panda et al 2006). It is well known that pH has a great importance in cation sorption because it influences chemical speciation of the metal in solution and also on the ionization of chemically active sites on the sorbent.…”