Vine pruning waste-based activated carbon for cerium and lanthanum adsorption from water and real leachate

In this study, vine pruning wastes (VPW) were used as raw material to develop an alternative activated carbon (VPW-AC) for adsorbing and concentrating rare earth elements cerium (Ce(III)) and lanthanum (La(III)) from synthetic and real leachate solutions. The Ce and La adsorption studies evaluated the effects of VPW-AC dosage, pH, contact time, rare earth initial concentration, and temperature. The VPW-AC adsorbent was subjected to many physicochemical characterization methods to correlate and understand its adsorptive performance. The characterization data indicate a carbonaceous adsorbent with a specific surface area of 467 m2/g. Zeta potential indicates a material with a negatively charged surface at a pH higher than 3.1, which is extremely beneficial to cations removal. For both rare earths elements (REEs), the adsorption capacity increases with the increase of the pH, reaching its maximum at pH 4–6. The kinetic data are well fitted by Avrami-fractional order, while the Liu model agreeably fits equilibrium data. The maximum adsorption capacities for Ce(III) and La(III) are 48.45 and 53.65 mg/g at 298 K, respectively. The thermodynamic studies suggest that the adsorption process is favorable, spontaneous, and exothermic for both REEs. Pore filling, surface complexation, and ion exchange are the dominant mechanisms. Finally, the VPW-AC was subjected to the recovery of REEs from real phosphogypsum leachate, and it is proved that it can be successfully used to recover REEs in a real process.