Lanthanum removal from spent catalysts of refinery applying electroremediation technique coupled to selective precipitation

Spent catalysts from fluid catalytic cracking have been a new opportunity for recovering metallic species from secondary sources, avoiding species waste, and also contributing to the circular economy, allowing the manufacture of new products. Regarding the techniques used, electrokinetic remediation coupled with selective precipitation arises as an appropriate alternative in the removal of lanthanum from refinery catalysts. To that end, the present work aimed to evaluate the recovery of lanthanum by selective precipitation using the effluent obtained from the electrokinetic remediation process of the spent catalyst from the fluid catalytic cracking process. Subsequently, some precipitation experiments were conducted in different temperatures of ammonium oxalate solutions to foster lanthanum oxalate precipitation, and the kinetic precipitation parameters were also obtained. The extraction of lanthanum ions from electroremediation resulted in 88.43%. Moreover, the best temperature to obtain lanthanum oxalate occurred at 25 °C, recovering 99.85% of the product, with an energy consumption of 100.19 W h g⁻¹. The results indicated that the precipitation reaction fitted a first-order model, presenting an activation energy of 58.3 kJ mol⁻¹. In light of these results, the coupling of electrokinetic remediation and selective precipitation techniques presented themselves as a suitable alternative to the recovery of metallic species from spent catalysts.