title: Sorption of copper by chemically modified aspen wood fibers.
abstract: Sorption of copper (Cu(2+)) by untreated and treated (bleaching and hydrolysis) aspen wood fibers, cellulose and lignin was examined to understand the Cu(2+) sorption behavior by these natural sorbents. All sorbents were characterized by solid-state (13)C NMR and FTIR. Bleaching broke up aromatic structures and increased hydrophilicity of the fibers, whereas hydrolysis decreased carbohydrate content, producing a more hydrophobic structure. Copper sorption was a function of pH; the percentage of Cu(2+) sorption steadily increased from pH 1.5 to 4.5 with a maximum sorption amount at around pH 5.5 for all the materials. All isotherms fitted well to the Langmuir equation. Bleached sample (BL) had a highest sorption capacity, followed by untreated (UTR), cellulose (CEL), and hydrolyzed (HHY), while lignin (LIG) had little Cu(2+) sorption under the studied conditions. The results suggested that carboxyl (-COOH) and hydroxyl (-CHOH) in carbohydrates are mainly responsible for Cu(2+) sorption, and that ion exchange may be a main sorption mechanism for the studied sorbents. Additionally, the sorption capacity for Cu(2+) on all sorbents decreased with the increase of the initial concentrations of Ca(2+), Na(+) or Al(3+). Copper sorption decreased rapidly at low initial concentrations of Ca(2+), Na(+) or Al(3+). However, the decline of Cu(2+) sorption slowed down when initial Na(+) and Ca(2+) concentration was higher than 0.05M or initial Al(3+) concentration was greater than 0.005M, indicating that specific adsorption may be taking place. Therefore, the majority of sorbed Cu(2+) to aspen wood fibers could be through ion exchange (especially, for UTR, BL and CEL), while a faction of sorbed Cu(2+) via inner-sphere complex (or specific adsorption).
authors.affiliation: Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, 01003, USA.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Huang
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Ou
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Boving
authors.forename: Julian
authors.initials: J
authors.lastname: Tyson
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D000327:Adsorption; D002482:Cellulose / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D008031:Lignin / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009994:Osmolar Concentration; D017550:Spectroscopy, Fourier Transform Infrared; D018508:Water Purification; D014934:Wood
chemical_list: D003300:Copper; D002482:Cellulose; D008031:Lignin