Treatment of leachates containing cobalt by adsorption on Spirulina sp. and activated charcoal

The search for efficient treatments for solid or liquid wastes containing heavy metals derived from new technologies, such as, smartphones and cell phones has increased in recent years. In this work, cobalt (Co(II)) was leached from spent lithium batteries (LIB's) and the leachate was treated by adsorption using Spirulina sp. and activated charcoal, aiming the Co(II) recovery. For both adsorbents, the study was firstly performed with synthetic solutions and after, realized with real leachates from LIB's. The study using synthetic solutions revealed that the adsorption was favored at pH of 6.0 for both adsorbents. Langmuir and Freundlich models were adequate to represent the adsorption equilibrium. The adsorption kinetic curves were well represented by the pseudo-second order model. The maximum adsorption capacities were 95.9 mg g−1 and 50.3 mg g−1 for Spirulina and activated charcoal, respectively. The study with real leachates revealed that 82% of Co(II) was recovered using Spirulina and 72% was recovered using activated charcoal. From these findings it is possible affirm that Spirulina is a renewable green alternative to recovery Co(II) from real leachates.