Electrodialytic processes in solid matrices. New insights into batteries 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 summarizes in this work. The influence of the pH value on the treatment effectiveness has been widely proved highlighting the phenomenon “water splitting” in the membrane surface. This dissociation of water molecules is related to the “limiting current” which is desirable to be exceed at the Anion Exchange Membrane in order to produce the entering of protons toward solid matrix. Other important parameters for the optimization of the technique, such as the current density and the liquid to solid ratio, are also discussed through the revision of studies using real solid matrices. This work also focusses 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 from spent batteries, such as Li and Co, incorporating principles of green chemistry.The authors acknowledge the financial support from the “Plan Propio de Investigación de la Universidad de Málaga with Project numbers: PPIT.UMA.B1.2017/20 and PPIT.UMA.B5.2018/17 and the European project THROUGH H2020-MSCA-RISE- 2017-778045. The first author also acknowledge the postdoctoral contract obtained from University of Malaga

Electrokinetic remediation of metal-polluted marine sediments: experimental investigation for plant design

This paper presents the results of an extensive set of laboratory experiments performed to design a demonstrative electrokinetic plant for extracting heavy metals from marine sediments dredged from the Livorno marine harbour. The investigated sediments displayed a high salinity, a high acid neutralization capacity, a low electrical resistivity (0.5 Ωm), a high alkalinity (pH ≈ 8) and a large fraction of fine particles. The target metals were Cd, Cr, Cu, Ni, Pb and Zn at relatively weak and inhomogeneous concentrations with high non-mobile fractions. After an accurate characterization, several screening and full electrokinetic tests were performed using cells of two different sizes, several conditioning agents (HNO3, HCl, H2SO4, citric acid, oxalic acid, ascorbic acid, EDTA), different applied current intensities and durations. The tests highlighted the need for long treatment times in order to obtain a significant pH reduction, with some appreciable metal removal being attained only after several weeks. The best results were obtained with strong acids used as the conditioning agents, with significant specific effects of each acid, including pronounced resistivity increase (from 0.5 up to 10 Ωm) and a high electroosmotic flow (EOF) with H2SO4, or a reversed EOF (electroendosmosis), and minor resistivity changes with HNO3. The use of the obtained data to design a demonstrative plant is also presented in the paper, with considerations on operating parameters such as energy and reagent consumption, characteristics of plant components and required safety measures. buffer capacity, conditioning agent

Optimal data fitting on lie groups: A coset approach

This work considers the problem of fitting data on a Lie group by a coset of a compact subgroup. This problem can be seen as an extension of the problem of fitting affine subspaces in n to data which can be solved using principal component analysis. We show how the fitting problem can be reduced for biinvariant distances to a generalized mean calculation on an homogeneous space. For biinvariant Riemannian distances we provide an algorithm based on the Karcher mean gradient algorithm. We illustrate our approach by some examples on SO(n). © 2010 Springer -Verlag Berlin Heidelberg

Synchronization with partial state feedback on SO(n)

In this paper we consider the problem of constructing a distributed feedback law to achieve synchronization for a group of k agents whose states evolve on SO(n) and which exchange only partial state information along communication links. The partial state information is given by the action of the state on reference vectors in ℝn. We propose a gradient based control law which achieves exponential local convergence to a synchronization configuration under a rank condition on a generalized Laplacian matrix. Furthermore, we discuss the case of time-varying reference vectors and provide a convergence result for this case. The latter helps reach synchronization, requiring less communication links and weaker conditions on the instantaneous reference vectors. Our methods are illustrated on an attitude synchronization problem where agents exchange only their relative positions observed in the respective body frames. ©2009 IEEE

Gradient-like observers on semidirect products

Abstract-This paper proposes a simple full state observer design for invariant state space systems where the state is evolving on a semidirect product of connected, finite-dimensional Lie groups. The design is based on a pair of cost functions defined on the Lie groups and consists of a copy of the observed system and a gradient-like innovation term. Under mild conditions the observer displays almost global exponential convergence. We illustrate the construction by an application in pose estimation