Development of novel composite adsorbents based on biopolymers/vermiculite using the ionic imprinting technique for cerium biosorption

Cerium is a rare earth metal with high demand in diverse industrial applications, thus, its recovery from sec-ondary sources is of fundamental importance, in a circular economy perspective. Biosorption is a recovery technique that stands out for its simplicity and efficiency. The combination of different materials is a strategy to produce biosorbents with improved properties. Biopolymers and clay minerals are considered promising because they are abundant and biodegradable. Functionalization techniques, such as ionic imprinting can improve the characteristics of biosorbents. The present work proposed the development of composite particles based on expanded vermiculite-biopolymers (chitosan, kappa-carrageenan, or alginate) and to evaluate their performance in terms of Ce3+ removal and particles solubility. The alginate-based composite provided the best results and was used in the synthesis of novel Ce3+ imprinted biosorbents. The particles with the best performance, composed of vermiculite (3% w/v) and alginate (2% w/v), without and with Ce3+ imprinting, presented biosorption capac-ities of 0.446 and 0.579 mmol/g, respectively. The kinetic study showed that the biosorption of Ce3+ by VALG3-II followed the pseudo-first order model. The selectivity of VALG3-II followed the order of Ce3+ > Al3+ > Fe2+ > Zn2+ > Ni2+ > Ca2+> Mg2+ > Na+ > K+. Additionally, the characterization of the composite without and with Ce3+ imprinting was performed by thermal analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, mercury intrusion porosimetry, helium pycnometry, and nitrogen physisorption.

Automated summary

The study developed composite particles based on expanded vermiculite-biopolymers, with alginate providing the best results, and novel Ce3+ imprinted biosorbents were synthesized. The biosorption capacities varied with different material combinations and improvement techniques.