A new composite material based on alginate and magadiite/Di-(2-ethylhexyl) phosphoric acid (CAM-D2EHPA) was successfully prepared by previous impregnation of layered magadiite with D2EHPA extractant, and then immobilized into the alginate matrix. Air dried beads of CAM-D2EHPA were characterized by FTIR and SEM–EDX techniques. The sorbent was used for the separation of lead and nickel from nitrate solutions; the main parameters of sorption such as contact time, pH of the solution, and initial metal concentration were studied. The beads recovered 94% of Pb(II) and 65% of Ni(II) at pH 4 from dilute solutions containing 10 mg L−1 of metal (sorbent dosage, S.D. 1 g L−1). The equilibrium data gave a better fit using the Langmuir model, and kinetic profiles were fitted using a pseudo-second order rate equation. The maximum sorption capacities obtained (at pH 4) were 197 mg g−1 and 44 mg g−1 for lead and nickel, respectively. The regeneration of the sorbent was efficiently carried out with a dilute solution of HNO3 (0.5 M). The composite material was reused in 10 sorption–elution cycles with no significant differences on sorption uptake. A study with synthetic effluents containing an equimolar concentration of both metals indicated a better selectivity towards lead ions.

Two low-cost renewable poplar-based materials were manufactured in this work for energy production and as sorbents for lead and terbium removal from aqueous effluents. Torrefaction was used as a pretreatment process for conditioning the raw biomass. Two different operating conditions were used in the multiple-hearth furnace of the torrefaction pilot-plant: i) 250°C; ii) 280°C, with residence times of 75 min and 60 min, respectively. The raw and torrefied biomasses have been characterized using SEM-EDX, FTIR, TGA, XRD and elemental analyses (C, H, N, S, O); an increase of the torrefaction severity, results in an increase of the carbon/oxygen ratio and in a greater mass loss (21% at 250°C, and 53% at 280°C). The torrefaction had a positive impact on the sorption of metals, it allowed the increase of lignin content of the manufactured materials, and it allowed the storage of the sorbents for longer time with reduced moisture content. The equilibrium studies were performed in batch system and the experimental data were described with the Sips equation. The maximum sorption capacity was found as 30 mg g −1 for lead and 9.4 mg g −1 for terbium (at pH 4). The kinetic profiles were fitted using the pseudo-second order rate equation. The regeneration of the sorbent was demonstrated by three sorption-desorption cycles using dilute HNO 3 solution (0.1 M) as eluent for metal recovery.

Na-magadiite-based materials have been studied for Cd(II) removal from waters  The sorbents were characterized with different techniques (XRD, FTIR, TGA, SEM-EDX)  The introduction of Cyanex-272 into the interlayers of Na-Magadiite was studied  The introduction of Cyanex-272 improves the selectivity towards cadmium ions