Selective lithium separation from desalination concentrates via the synergy of extractant mixtures

Seawater reverse osmosis (SWRO) desalination plants generate high volumes of concentrates, which contain, in addition to major salts, some elements of growing interest in minor concentrations. This is the case of lithium, highly demanded in the battery industry. In this work, the separation of Li+ from model SWRO brines has been evaluated by obtaining Li+ extraction curves with the combination of extractants DBM-TOPO and FDOD-TOPO, proving that both mixtures are capable of extracting Li+ under basic pH conditions, due to the keto-enolic tautomerism of the b-diketones. Li+ extraction values of 95.4 % for DBM-TOPO (pH = 12.2) and 100 % for FDOD-TOPO (pH = 9.0) were achieved. This behaviour was verified by the FT-IR analysis of the sample before and after the Li+ extraction. Finally, the selective separation of Li+ against other cations, such as Na+, K+, Mg2+, Ca2+ and Sr2+, present in the model brines at higher concentrations, was determined. Under mentioned experimental conditions, these cations are not extracted, reaching to Li+ selective separation close to 100 %. This study shows the first results on the selective extraction of lithium in complex SWRO brines, fostered through promising extractants mixtures showing a synergic effect towards Li+ in such multicomponent matrices.This research was developed in the framework of the projects PID2020-115409RB-I00, PDC2021-120786-I00 and TED2021-129874B-I00 financed by the Ministry of Science and Innovation (Spain). Elena Fernández-Escalante is grateful for the predoctoral contract PRE2021-100160

Formation of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the electrochemical oxidation of polluted waters with pharmaceuticals used against COVID-19

The COVID-19 pandemic has produced a huge impact on our lives, increasing the consumption of certain pharmaceuticals, and with this, contributing to the intensification of their presence in wastewater and in the environment. This situation demands the implementation of efficient remediation technologies, among them, electrochemical oxidation (ELOX) is one the most applied. This work studies the application of ELOX with the aim of eliminate pharmaceuticals used in the fight against COVID-19, assessing its degradation rate, as well as the risk of formation of toxic trace by-products, such as unintentional POPs like polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). To this end, model solutions containing 10 mg L-1 of dexamethasone (DEX), paracetamol (PAR), amoxicillin (AMX), and sertraline (STR) with two different electrolytes (NaCl and Na2SO4) have been evaluated. However, electrochemical systems that contain chloride ions in solution together with PCDD/Fs precursor molecules may lead to the formation of these highly toxic by-products. So, PCDD/Fs were quantified under conditions of complete degradation of the drugs. Furthermore, the presence of PCDD/Fs precursors such as chlorophenols was determined, as well as the role of Cl-, Cl- and radicals in the formation of the by-products and PCDD/Fs. The maximum measured concentration of PCDD/Fs was around 2700-pg-L-1 for the amoxicillin case in NaCl medium. The obtained results emphasise the importance of not underestimating the potential formation of these highly toxic trace by-products, in addition to the correct selection of oxidation processes and operation variables, in order to avoid final higher toxicity in the medium.This research was developed in the framework of the project PID2020–115409RB-I00 (MCIN/AEI) financed by the Spanish Ministry of Science and Innovation. Sophie Schroder is also grateful to MCIN for the FPI grant PRE2018–83526

Photocatalytic transformation of triclosan. Reaction products and kinetics

5-Chloro-2-[2,4-dichlorophenoxy]-phenol, or triclosan (TCS), is an antimicrobial and antifungal agent with high resistance to conventional wastewater treatments, thus, more effective remediation technologies are necessary, where photocatalytic processes deserve special attention due to the high degradation rates of TCS, and the use of a renewable source of energy. However, different by-products may be formed during the treatment, sometimes more harmful than the parent compounds. Efforts to detail reaction pathways continually feed into related literature; however, knowing the transformation kinetics and the dependence on the operating variables is essential for the correct design of the abovementioned remediation technologies. This work contributes to increasing the knowledge necessary for the application of photocatalytic processes for the degradation of emerging pollutants, with TCS as a case study. First, an experimental plan to analyze the influence of the operating variables was carried out, determining time courses of the parent and intermediate compounds. Next, the kinetic model and parameters that are capable of predicting TCS concentration and its derivatives as a function of the operating conditions are provided. This constitutes a very useful tool to predict the performance of wastewater remediation treatment both in the degradation of the original pollutant and in the reduction of the toxicity in the treated water.This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) (CTM2017-87740-R and RTI2018-093310-B-I00)

Fixed-bed columns mathematical modeling for selective nickel and copper recovery from industrial spent acids by chelating resins

Spent acid streams generated in industry containing high concentrations of heavy metals are potential secondary sources of raw materials. Chelating resins are excellent candidates to recover valuable metals from complex mixtures at very low pH conditions. In particular, previous works reported high recoveries of nickel and copper from real industrial acids (3400 mg Cu2+ L−1, 8700 mg Ni2+ L−1 and 24000 mg Fe L−1) using commercial bis-picolyamine (BPA)-based resins. In this work, adsorption and desorption using two in-series fixed-bed columns with BPA resins have been proposed to carry out the selective and independent separation and recovery of nickel and copper. Under the selected operating conditions, it was possible to recover 90% of the copper and 80% of the nickel present in the problem solution. A mathematical model based on mass transfer was developed in order to describe the adsorption and desorption stages. Adsorption chemical reactions were modeled as equilibrium reactions, fitting to Langmuir’s and Freundlich’s isotherms for copper and nickel respectively. The chemical reactions for both metals in desorption fitted into first order reactions. Finally, the kinetic constants kde=0.81 kgdryresin L−1 h−1 for copper and kde=1.10 kgdryresin L−1 h−1 for nickel were estimated using the software Aspen Custom modeler. The predicted values agreed with the experimental data.This research was developed in the framework of the projects PID2020-115409RB-I00, PDC2021-120786-I00, TED2021-129874B-I00 and PID2021-122563OB-I00 financed by the Ministry of Science and Innovation (Spain)

New challenges and applications of supported liquid membrane systems based on facilitated transport in liquid phase separations of metallic species

The linear economic model based on "take-make-dispose" has become unsustainable, revealing the necessity of shifting towards a circular economy (CE) approach, in which secondary raw materials play a key role in closing material cycles. In this context, industrial effluents with metallic content, are considered a potential secondary source for these elements, the lack of the availability of the appropriate technology being the main barrier when implementing circular economy principles at industrial scale. In this regard, supported liquid membrane (SLM) systems based on facilitated transport may be decisive. Thus, the objective of this research paper is to show the potential of facilitated transport systems to foster the transition to a more sustainable management of industrial metallic effluents. To accomplish that, three different applications of supported liquid membrane systems in acidic industrial effluents will be presented: a) Zn/Fe separation, b) Ni/Cd separations and c) Removal of hexavalent Cr. Additionally, the recovery and separation of two different critical raw materials, i.e. Li and rare earth elements will be discussed. Although facilitated transport systems have been successfully applied to both, Zn/Fe and Ni/Cd separation, as well as to hexavalent Cr removal, further work should be done for the successful recovery and separation of Li and rare earths with supported liquid membrane systems, especially in terms of selectivity improvement and validation with real industrial effluents.Financial support from the Spanish Ministry of Science, Innovation and Universities under the projects PID2020-115409RB-I00 and RTI2018-093310-B-I00 are gratefully acknowledged

Método espectroscópico para la determinación de proteínas en medios complejos

Método espectroscópico para la determinación de proteínas en medios complejos. La presente invención se refiere a un método determinación cuantitativa de dos proteínas con características similares en una muestra, basado en medidas espectroscópicas de fluorescencia y absorción en UV. Este método permite obtener la concentración de las proteínas de una forma sencilla y rápida evitando la destrucción de la muestra, y es útil en los sectores biotecnológico o alimentario.Solicitud: 201400165 (28.02.2014)Nº Pub. de Solicitud: ES2464440A1 (02.06.2014)Nº de Patente: ES2464440B2 (06.11.2014

Potential formation of PCDD/Fs in triclosan wastewater treatment: an overall toxicity assessment under a life cycle approach

Wastewater may contain a diverse group of unregulated pollutants known as emerging pollutants, such as pharmaceuticals and personal care products (PPCPs). Triclosan (TCS) is a personal care product widely used as an antiseptic or preservative in cosmetics, hand wash, toothpaste and deodorant soaps. Advanced oxidation processes (AOPs) have been used as effective and alternative treatments for complex wastewater. However, an important criterion for the assessment of AOPs and their operation conditions could be the potential formation of new toxic secondary products, such as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), especially when emerging pollutants are present in the media. If these are omitted from environmental management studies, the real environmental impacts of a WWTPs (wastewater treatment plants) may be underestimated. Consequently, the current study aims to evaluate the environmental impacts derived from electrooxidation (EOX), one of the most effective oxidation technologies, of emerging pollutants using Life Cycle Assessment. The analyses were performed for the treatment of effluents containing TCS, firstly without considering the formation of PCDD/Fs and, thereafter, considering the effects of these compounds. Total toxicity, calculated through different methods and corresponding impact factors, were evaluated for each stage of the process when different electrolytes are used, including PCDD/Fs formation. Finally, a sensitivity analysis was carried out to study i) the effect of the TCS initial concentration on the environmental impacts associated to ecotoxicity for the different life cycle methods and ii) the influence of changing the organic pollutant on PCDD/Fs formation employing 2-chlorophenol (2-CP). As a result, LCIA methods demonstrate that they are not fully adapted to the computation of PCDD/Fs in the water compartment, since only 2,3,7,8-tetraclorodibenzo-p-dioxina (2,3,7,8-TCDD) is present as a substance in the impact categories assessed, ignoring the remaining list of PCDD/Fs.This research was developed in the framework of the project CTM2017-87740-R and CTM2016-76176-C2-1-R financed by the Spanish Ministry of Economy and Competitiveness (MINECO). Claudia Solá-Gutiérrez and Sophie Schröder are also grateful for its correspondent FPI grant BES-2015-072920 and PRE2018-083526, respectively. Ian Vázquez-Rowe wishes to thank the Dirección General de Investigación (DGI), Project N°636, and the Dirección Académica de Relaciones Internacionales (DARI) from the Pontificia Universidad Católica del Perú (PUCP) for financial support during his stay at the Universidad de Cantabria (Spain)

Selective extraction of lithium from seawater desalination concentrates: study of thermodynamic and equilibrium properties using Density Functional Theory (DFT)

Lithium, declared critical raw material by the European Union in 2020, is a competitor to hydrogen as alternative to petroleum. Its use is increasing while reserves are declining, boosting new sources, as seawater desalination concentrates. In this work, a computational study of the most promising extractants, B-diketones and organophosphates and combinations thereof, towards lithium in presence of metal ions found in the concentrates, Na+, K+, Mg2+, Ca2+ and Sr2+ was carried out, via molecular simulation using ab initio Density Functional Theory (DFT). The geometries, reaction energies, and thermodynamic parameters have been evaluated. Using the square of the electronic wave function an electrostatic interaction was confirmed as cation-extractant/s bonding. The complexation reaction energies of the systems formed by a cation and a single extractant display negative [delta]E and [delta]G values, pointing towards stable complexes and spontaneous reactions. The synergic effect of extractants was studied by combining the [beta]-diketones with TOPO (1:1) leading to an increase of [delta]E and [delta]G (absolute value). The extraction coefficient, K, follows the order K(K+) > K(Na+) > K(Li+) > K(Sr2+) > K(Ca2+) > K(Mg2+). In consequence, selectivity Li+ towards cations of the group II was higher, S(Li+/Mg2+) > S(Li+/Ca2+) > S(Li+/Sr2+) for the combined mixtures BTA TOPO and FDOD TOPO and lower towards group I cations, S(Li+/Na+) > S(Li+/K+) for DBM TOPO and LIX54 TOPO. The selectivity of Li+ regarding the rest of the cations and the 16 extractants and mixtures of extractants was lower than the selectivity of Li+ with respect to each cation, being the best value for the DBM TOPO and LIX54 TOPO systems. The results obtained are expected to provide a tool on the behaviour of the most promising of extractants towards Li+ in seawater desalination concentrates.This research was developed in the framework of the project PID2020-115409RB-I00 financed by the Ministry of Science and Innovation (Spain)

Changes in PCDD/Fs concentration during the advanced oxidation treatment of landfill leachates

Financial support from project CTQ2011-25262 (the Spanish Ministry of Science and Innovation, MCI, Spain)

Opportunities of desalination concentrates for lithium recovery: optimal separation by synergic solvents

Lithium, highly demanded for its use in the battery industry, among other applications, has become a vulnerable commodity due to shortages in traditional sources. Although it is found in low concentration in SWRO brines, this waste represents a new source of this raw material. Based on previous studies in which Li+ extractions > 95 % were achieved, the optimal separation conditions of lithium from SWRO concentrates by solvent extraction with DBM•TOPO and FDOD•TOPO have been obtained for the first time. To this end, response surface methodology (RSM) with a three-level central composite design (CCD) has been applied. Three process variables, extractant concentration, basicity of the aqueous phase, and molar ratio between extractants, were evaluated using statistical parameters and second-order regression models. The optimized variables achieved maximum predicted extraction values of 99.7 % for DBM•TOPO and 100 % for FDOD•TOPO, not found yet in the open literature. Notably, for FDOD•TOPO system the needed pH for extraction is reduced, and both systems require a DBM:TOPO and FDOD:TOPO less than 1, a crucial consideration in terms of cost. This study opens new opportunities for lithium supply through desalination concentrates recovery.This research was developed in the framework of the projects PID2020-115409RB-I00, PDC2021-120786-I00 and TED2021-129874B-I00 financed by the Ministry of Science and Innovation (Spain). Elena Fernández-Escalante is grateful for the predoctoral contract PRE2021-100160