Efficient adsorption of Cd(Ⅱ) ions from aqueous media onto a semi-interpenetrating bio-composite

摘要

New bio-composite, semi-interpenetrating biopolymers (obtained from hydrolyzed carboxymethyl cellulose grafted polyacrylonitrile [h-CMC-g-PAN] and sodium alginate [Na-Alg] using CaCl2 as a cross linker; semi-interpenetrating biopolymers [s-IPNs]) have been prepared and fully characterized using spectroscopic (FTIR, scanning electron microscopy, EDS), elemental analysis, and thermal analysis measurements measurements. The morphology and structure of these s-IPNs are different from those obtained with solely h-CMC-g-PAN and Na-Alg indicating successive functionalization. The availability of the functional-rich bio-composites has afforded an excellent opportunity to test them as sorbents for the uptake of toxic Cd(II) ions from aqueous media. Subsequently, the uptake of Cd(II) ions was shown to be dependent on the pH, shaking time, temperature, amount of sorbent, and the initial concentration of the Cd(II) ions. The maximum Cd(II) ion uptake was 99.5% at pH 6, using 50 mg of sorbent with 120 min shaking time at 25 degrees C. The adsorption isotherm fitted well with Langmuir model, with calculated maximum adsorption capacity 49.75 mg g(-1). The kinetic studies were modeled using a pseudo second-order reaction. The thermodynamic parameters (Delta H-o, Delta G(o), and Delta S-o) of the uptake of Cd(II) ions onto s-IPNs were found to be -13,176.07 Jmol(-1), -4,572.7 Jmol(-1), and 28.87 J K-1 mol(-1), respectively, verifying spontaneous exothermic process. Successive desorption and reusability of s-IPNs for the uptake of Cd(II) indicated, its high efficiency over three cycles.