Electrodialytic processes in solid matrices. New insights into battery recycling. A review

Electrodialytic remediation has been widely applied to the recovery of different contaminants from numerous solid matrices, solving emerging issues of environmental concern. Results and conclusions reported in studies about real contaminated matrices are summarized in this work. The influence of pH value on the treatment effectiveness has been widely proved, highlighting the phenomenon of 'water splitting' in the membrane surface. This dissociation of water molecules is related to the 'limiting current' which it is desirable to exceed at the anion exchange membrane in order to produce the entering of protons toward the solid matrix. Other important parameters for the optimization of the technique, such as the current density and the liquid/solid ratio, are also discussed through the revision of studies using real solid matrices. This work also focuses on the pioneer proposal of electrokinetic technologies for the recycling of lithium ion batteries, considering the relevance of waste properties in the design and optimization of the technique. From a thorough literature revision, it could be concluded that further experimental results are needed to allow an optimal application of the technique to the rising problem of residues from batteries. The main aim of this work is to take the first steps in the recovery of valuable metals such as Li and Co from spent batteries, incorporating principles of green chemistry. (c) 2019 Society of Chemical Industry