Grafting of aminated oligogalacturonans onto Douglas fir barks. A new route for the enhancement of their lead (II) binding capacities.
ABSTRACT Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of PbII from aqueous solutions was investigated. A new approach to enhance the natural properties of bark by covalent grafting of oligogalacturonans was developed. The polysaccharidic moiety of barks was functionalized by periodate oxidation and derivatized after reductive amination in presence of aminated oligogalacturonic acid. PbII adsorption isotherms of derivatized barks were then determined and compared with the capabilities of crude barks using the Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (q(max)). Derivatization resulted in significant enhancements of the q(max) values (up to x8), along with little change of the affinity parameter.
- [show abstract] [hide abstract]
ABSTRACT: Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of Pb from aqueous solutions was investigated. We developed a new solvent‐free approach to enhance the natural properties of bark by utilizing polyfunctional groups covalently attached at their surface. The hydroxyl groups of their polysaccharide moiety were functionalized by periodate oxidation and derivatized via reductive amination in presence of aspartic acid or 4,4′‐diamino‐2,2′‐stilbene disulfonic acid. The degree of substitution of derivatized bark was estimated by the means of pH titration. Adsorption isotherms of Pb on derivatized barks were determined and compared with the performances of crude bark. Adsorption was characterized using the noncompetitive Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (qmax). Derivatization resulted in enhancements of both qmax (×4–7) and b (×1.5–10). These experimental data are discussed in the context of the Hard and Soft Acid and Base theory.SSTEDS. 01/1595; 39(7):1595-1610.
- [show abstract] [hide abstract]
ABSTRACT: The biosorption potential of pine (Pinus brutia Ten.) bark in a batch system for the removal of Pb(II) ions from aqueous solutions was investigated. The biosorption characteristics of Pb(II) ions on the pine bark was investigated with respect to well-established effective parameters including the effects of solution pH, initial Pb(II) concentration, mass of bark, temperature, and interfering ions present, reusability, and desorption. Initial solution pH and contact time were optimized to 4.0 and 4 h, respectively. The Langmuir and Freundlich equilibrium adsorption models were studied and observed to fit well. The maximum adsorption capacity of the bark for Pb(II) was found to be 76.8 mg g−1 by Langmuir isotherms (mass of bark: 1.0 g L−1). The kinetic data fitted the pseudo-second-order model with correlation coefficient greater than 0.99. The thermodynamic parameters Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) changes were also calculated, and the values indicated that the biosorption process was spontaneous. Reutilization of the biosorbent was feasible with a 90.7% desorption efficiency using 0.5 M HCl. It was concluded that pine bark can be used as an effective, low cost, and environmentally friendly biosorbent for the removal of Pb(II) ions from aqueous solution.Chemical Engineering Journal. 01/2009;
- Chemical Engineering Journal 01/2010; 20:357-365. · 3.47 Impact Factor