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 38 mg La g(-1) for cellulose to 101 and 170 mg La g(-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 150-180 min. The thermodynamic study shows that the reaction is spontaneous, endothermic and entropic. Nitric acid solutions (0.5 M 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. (C) 2016 Elsevier Ltd. All rights reserved.