Ahmed A. Galhoum

Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Light and Heavy Rare Earth Metals: Uptake Kinetics and Sorption Isotherms

Cysteine-functionalized chitosan magnetic nano-based particles were synthesized for the sorption of light and heavy rare earth (RE) metal ions (La(III), Nd(III) and Yb(III)). The structural, surface, and magnetic properties of nano-sized sorbent were investigated by elemental analysis, FTIR, XRD, TEM and VSM (vibrating sample magnetometry). Experimental data show that the pseudo second-order rate equation fits the kinetic profiles well, while sorption isotherms are described by the Langmuir model. Thermodynamic constants (ΔG°, ΔH°) demonstrate the spontaneous and endothermic nature of sorption. Yb(III) (heavy RE) was selectively sorbed while light RE metal ions La(III) and Nd(III) were concentrated/enriched in the solution. Cationic species RE(III) in aqueous solution can be adsorbed by the combination of chelating and anion-exchange mechanisms. The sorbent can be efficiently regenerated using acidified thiourea.

Uranium and neodymium biosorption using novel chelating polysaccharide

A direct reaction is described to prepare hydrophobic α-aminomethylphosphonic acid as a novel chitosan-based material. It exhibits chelating properties for polyvalent metal ions such as U(VI) and Nd(III) ions. The new sorbent was fully characterized using Elemental analysis, scanning electron microscope (SEM) and FTIR spectra. Different parameters were examined in order to evaluate the optimum conditions for U(VI) and Nd(III) ions biosorption. Sorption mechanisms of metal ions were investigated using kinetic and isotherm models. In addition, the sorbent selectivity was tested for both metal ions together in a binary solution.

Synthesis and characterization of poly(carboxymethyl)-cellulose for enhanced La(III) sorption

The grafting of amino and carboxylic acid groups on cellulose increased La(III) sorption efficiency of cellulose: maximum sorption capacity increased from 38mgLag-1 for cellulose to 101 and 170mgLag-1 for amino derivative (PAC) and amino-carboxylic derivative (PCMC). Langmuir equation successfully fits sorption isotherms while uptake kinetics are effectively modeled using the pseudo-first order rate equation (though resistance to intraparticle diffusion plays a significant role in the control of metal recovery). Uptake equilibrium occurred within 150-180min. The thermodynamic study shows that the reaction is spontaneous, endothermic and entropic. Nitric acid solutions (0.5M concentration) can be efficiently used for metal recovery and sorbent can be recycled for at least 5 cycles with limited decrease in sorption performance for the three sorbents. The materials were characterized by elemental analysis, acid-base titration, FTIR spectrometry, x-ray diffraction analysis, X-ray photoelectron spectroscopy, SEM-EDX analysis and also by TGA.

Cysteine-Functionalized Chitosan Magnetic Nano-Based Particles for the Recovery of Uranium(VI): Uptake Kinetics and Sorption Isotherms

Magnetic-chitosan nanoparticles, functionalized with cysteine, were synthesized and characterized by element analysis, FT-IR, XRD, TEM, and vibrating sample magnetometry. The sorbent was tested for U(VI) recovery, considering: a. pH effect, b. sorption isotherms (fitted by Langmuir equation), and c. uptake kinetics (modeled using the PSORE). Maximum sorption capacity approached 100 mg U g−1. The nanometric size of sorbent reduces the impact of resistance to intraparticle diffusion; this may explain the fast kinetics (equilibrium within 50 min). The reaction is exothermic, spontaneous. The metal could be desorbed using acidified urea solution and the sorbent could be recycled for 5 cycles.

Evaluation of adsorption behavior for U(VI) and Th(IV) ions onto solidified Mannich type material

ABSTRACT Treatment of aqueous solution contaminated by uranium and thorium using a new Mannich type resin was studied. Different instrumental techniques such as elemental analysis, FTIR, and thermogravimetric analysis were employed for full characterization of the synthetic resin. Adsorption behavior was studied by batch experiments to determine the optimum conditions for U(VI) and Th(IV) ion removal. The adsorption studies showed the best fit with the second order rate equation and Langmuir model. The adsorption process is endothermic, spontaneous, and of increased disorder. The regeneration of sorbent was carried out using diluted HCl and the reuse of sorbent remains appreciable. GRAPHICAL ABSTRACT