New Perspectives for Electrodialytic Remediation

Electrodialytic remediation has been widely used for the recovery of different contaminants from numerous matrices, such as, for example, polluted soils, wastewater sludge, fly ash, mine tailing or harbour sediments. The electrodialytic remediation is an enhancement of the electrokinetic remediation technique, and it consists of the use of ion-exchange membranes for the control of the acid and the alkaline fronts generated in the electrochemical processes. While the standard electrodialytic cell is usually built with three-compartment configuration, it has been shown that for the remediation of matrices that require acid environment, a two-compartment cell has given satisfactory removal efficiencies with reduced energy costs. Recycling secondary batteries, with growing demand, has an increasing economic and environmental interest. This work focusses on the proposal of the electrodialytic remediation technique as a possible application for the recycling of lithium-ion cells and other secondary batteries. The recovery of valuable components, such as lithium, manganese, cobalt of phosphorous, based on current recycling processes and the characterization of solid waste is addressed.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Electrodialytic Recovery of Cobalt from Spent Lithium-Ion Batteries

Contribución en congreso científicoRecycling lithium-ion batteries has an increasing interest for economic and environmental reasons. Disposal of lithium-ion batteries imposes high risk to the environment due to the toxicity of some of their essential components. In addition to this, some of these components, such as cobalt, natural graphite and phosphorus, are included in the list of critical raw materials for the European Union due to their strategic importance in the manufacturing industry. Therefore, in the recent years, numerous research studies have been focused on the development of efficient processes for battery recycling and the selective recuperation of these key components. LiCoO2 is the most common material use in current lithium-ion batteries cathodes. In the current work, an electrodialytic method is proposed for the recovery of cobalt from this kind of electrode. In a standard electrodialytic cell, the treated matrix is separated from the anode and the cathode compartments by means of ion-exchange membranes. A cation-exchange membrane (CEM) allows the passage of cations and hinders the passage of anions, while the behaviour of anion-exchange membrane (AEM) does the opposite. A three-compartment electrodialytic cell has been designed and assembled, as depicted in the figure. In the central compartment, a suspension of LiCoO2 is added. Different extracting agents, such as EDTA, HCl and HNO3, are tested to enhanced the dissolution and the selective extraction of the target metal. Dissolved cobalt-containing complexes migrate towards the cathode or the anode compartments depending on the ionic charge of the complexes. While cobalt extraction via extracting agents is an expensive treatment, as it requires the constant addition of chemicals, an efficient electrodialytic cell could allow the recirculation of the extracting agents and the economical optimization of the process.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Acid leaching of LiCoO2 enhanced by reducing agent. Model formulation and validation.

In this work, a model has been formulated to describe the complex process of LiCoO2 leaching through the participation of competing reactions in acid media including the effect of H2O2 as reducing agent. The model presented here describes the extraction of Li and Co in the presence and absence of H2O2, and it takes into account the different phenomena affecting the controlling mechanisms. In this context, the model predicts the swift from kinetic control to diffusion control. The model has been implemented and solved to simulate the leaching process. To validate the model and to estimate the model parameters, a set of 12 (in triplicate) extraction experiments were carried out varying the concentration of hydrochloric acid (within the range of 0.5–2.5 M) and hydrogen peroxide (range 0–0.6%v/v). The simulation results match fairly well with the experimental data for a wide range of conditions. Furthermore, the model can be used to predict results with different solid-liquid ratios as well as different acid and oxygen peroxide concentrations. This model could be used to design or optimize a LiCoO2 extraction process facilitating the corresponding economical balance of the treatment.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska- Curie grant agreement No. 778045 and the “Proyectos I+D+i en el marco del Programa Operativo FEDER Andalucía 2014–2020”, Project no. UMA18-FEDERJA-279. Cerrillo-Gonzalez acknowledges the FPU grant (FPU18/04295) obtained from the Spanish Ministry of Education. Funding for open access charge: Universidad de Málaga / CBUA

Alternative reducing agents for Lithium-Ion batteries recycling via hydrometallurgical process

Lithium-ion batteries (LIB) are a key factor in the transition to a decarbonised and clean energy system due to their application in the power sector and electric transport. However, a growing demand of these batteries involves two direct problems: an increase in the generation of spent LIBs as well as in the demand of raw materials. Hence, the development of efficient recycling treatment of LIBs is crucial to make them a true enabler of the green transition. Currently, the LIBs recycling process can be divided into pyrometallurgical and hydrometallurgical. The first one is based on the treatment of LIBs at high temperatures to produces metal pyrolysis and metal reduction, while the second method consists in the recovery of metals via acidic leaching. Although pyrometallurgical method is the most used in the industry, hydrometallurgical process presents a series of advantages, such as low energy consumption, high metal recovery and high product purity, that make it more promising in the search of more effective recycling method. In the hydrometallurgical process, the addition of acids and reducing agents is required to dissolve the solid particles and extract the valuable metals. The purpose of this work was to evaluate the effect of alternative reducing agent in the leaching process to maximize the amount of metal (Mn, Li, Ni, Co) recovered from a real LIBs waste. With this aim, the leaching processes were carried out using as reducing agent H2O2, Fe and NH4Cl. According to the experimental results, Fe and NH4Cl enhance the extraction yield as well as the reaction time comparing with the results obtain using H2O2.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Characterization and modeling of lithium-polymer commercial batteries

Lithium-ion batteries are key for the modern society as they are present in many energy storage devices and have promising future perspectives in the field of electric cars and energy accumulators from renewable sources. Herein, we present results from charge and discharge cycles on batteries with controlled conditions. The cyclability of commercial lithium-polymer “pouch” batteries, has been studied under different charge/discharge rate and temperatures. The relationship between the state of charge and the cell voltage has been obtained, and the degradation of the cell energy capacity after a number of cycles has been measured. Furthermore, the experimental results have been compared with simulations based on Newman’s model for Lithium Ion Batteries, carried out using COMSOL Multiphysics software. The results show the correlation between temperature, C-rate and degradation in lithium ion batteries. It is especially remarkable the decrease of the apparent capacity of batteries at low temperatures, and the increase of the degradation at higher temperatures. These results are essential for the design of control mechanisms that can prevent battery failure.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Plan Propio de Investigación y Transferencia de la Universidad de Málaga, Proyecto Puente B.5, código: PPIT.UMA.B5.2018/1

Sequential extraction procedure: a versatile tool for environmental research

The sequential extraction procedure as a tool to assess the environmental risk of metals in solid matrices has been widely studied. In this work, other promising application of these methods is proposed: the evaluation of the recoverability of critical raw materials from a solid matrix. To this aim, the normalized sequential extraction procedure BCR was applied to a real contaminated soil from the south of Spain. In addition to this, the influence of the incomplete dissolution of carbonates contained in the soil on the fractionation results has been also studied. The high percentage of metal in the most mobile fractions suggested the potential use of the solid matrix as secondary source. The use of this approach together with environmental and economic feasibility studies would be an approach toward the circular economyThis work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. The University of Malaga is acknowledged for the financial support in the postdoctoral fellowship of Villen-Guzman. Cerrillo-Gonzalez acknowledges the FPU grant obtained from the Spanish Ministry of Education. Paz-Garcia acknowledges the financial support from the program “Proyectos I+D+i en el marco del Programa Operativo FEDER Andalucía 2014-2020”, No. UMA18-FEDERJA-279

The use of available chemical equilibria software for the prediction of the performance of EKR

Risk assessment aims for the prediction of the mobility of contaminants, and these are usually based in lab essays together with mathematical modelling. Also the feasibility studies of most techniques, require similar tools. Frequently the lab characterization is based in the chemical fractionation of the contaminants based on their mobility under different chemical reagents. Probably the most frequent fractionation technique for heavy metal contaminated soils is the BCR [1]. The use of chemical equilibria software helps to understand the processes involved in the contaminant transport during electrokinetic remediation. Most mathematical models used for the simulation of electrokinetic decontamination assume local equilibrium between the chemicals present in the aqueous phase. In other cases also equilibrium is supposed between the chemical species present in the aqueous phase and the solid matrix. In this work, we compare the results of batch extraction experiments with those obtained using Visual MINTEQ [2]. This is a free software that allows a reliable simulation of the chemical processes involved in the water-soil systems such as solubility, sorption, etc. We found that even when the main contaminant behaviour is in accordance with the local equilibrium assumption, the mobilization of other metals, such as Ca and Mg, that are also present in important concentrations, are affected by kinetic limitations. These kinetic limitations have important effects in the overall behaviour of the system. Thus, if ignored, important flaws will appear in the predictions of the model with respect to those toxic species that could be considered to behave under local equilibrium. [1] M. Villen-Guzman, J.M. Paz-Garcia, J.M. Rodriguez-Maroto, C. Gomez-Lahoz and F. Garcia-Herruzo. Acid Enhanced Electrokinetic Remediation of a Contaminated Soil Using Constant Current Density: Strong vs. Weak Acid. Separation Science and Technology (in press; DOI 10.1080/01496395.2014.898306). [2] J.P. Gustafsson, Visual MINTEQ ver. 3.0beta. KTH Royal Institute of Technology, Dept. of Land and Water Resources Engineering, Stockholm, Sweden. (2010) http://www2.lwr.kth.se/English/OurSoftware/vminteq/index.htmlUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Electrodialytic Treatment of Secondary Batteries Cathodes

The interest for reusing and recycling secondary batteries is increasing, driven by both economic and environmental reasons. Lithium-ion batteries are among the main energy storage devices more popular in portable electronic and there are being used more every year in the field of electric transportation. The growing demand for rechargeable batteries entails an increase in the attention paid to the recycling of spent batteries due to the toxicity of some of their essential components. Furthermore, some of these components, such as cobalt, natural graphite and phosphorus, are included in the list of critical raw materials for the European Union due to their strategic importance in the manufacturing industry. Therefore, the development of new technologies to selectively recover these key components should be addressed. In this work, an electrodialytic method is applied to real battery wastes previously submitted to a pre-treatment process (Figure 1). We focused on the extraction of Co and Li from spent cathodes, in combination with acid-extraction and different oxidation/reduction environments. The optimization of some of the most relevant operating parameters, such as cell design, selection of enhancing agent and current density has been carried out according to the lithium-ion batteries waste characteristic. Results indicate that the electrodialytic method could be a useful technique for the selective extraction of Li and Co from spent batteries. Furthermore, the deposition of Co at the cathode surface may be optimized to separate the cations at the catholyte, for a direct reincorporation in the manufacturing chain.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. The authors acknowledge the financial support from the "Plan Propio de Investigación de la Universidad de Málaga" with project numbers, PPIT.UMA.D1, PPIT.UMA.B1.2017/20 and PPIT.UMA.B5.2018/17. This work has also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045

Improving Cr (VI) Extraction through Electrodialysis

A laboratory study has been carried out to determine the feasibility of in situ remediation of chromium (VI) contaminated soil using electrodialysis. In a classic setup, this technique implies the application of a low intensity direct current to the soil, which is separated from the electrode compartments by ion-exchange membranes. If the pollutants are ionic compounds, they can be forced to migrate to the oppositely charged electrode by electro-migration. Membranes selectively impede the flow of ions in the electrode compartments back to the soil. If a metal species is naturally present as an anion, mobilization from the soil at alkaline pH can be realized and, at the same time, the mobilization of other metal cations that occur at low pH can be minimized. Experiments have been carried out with clayey soils (kaolinite clay and soil clay mixtures) that have been characterized and then contaminated by mixing with a potassium dichromate solution for several days. Initial Cr (VI) content ranges from 500 to 4000 mg/kg. Treatment tests were carried out in an acrylic laboratory cells consisting of a central soil compartment and two electrode compartments located at both ends of the column. Dimensionally stable titanium electrodes coated with mixed metal oxides were placed in the electrode compartments. 0.01M Na2SO4 electrolytes were recirculated through them from two 1-liter deposits using a peristaltic pump. Two commercial ion exchange membranes separated the anolyte and catholyte compartments from the soil in the standard configuration. A programmable DC: power supply was connected to the electrodes and a computer for data acquisition.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. The authors acknowledge the financial support from the "Plan Propio de Investigación de la Universidad de Málaga" with project numbers PPIT.UMA.D1; PPIT.UMA.B1.2017/20 and PPIT.UMA.B5.2018/17. This work has also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045