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Seawater represents a potential resource for raw materials extraction. Although NaCl is the most representative mineral extracted other valuable compounds such as Mg, Li, Sr, Rb and B and elements at trace level (Cs, Co, In, Sc, Ga and Ge) are also contained in this “liquid mine”. Most of them are considered as Critical Raw Materials by the European Union. Solar saltworks, providing concentration factors of up-to 20 to 40, offer a perfect platform for the development of minerals and metal recovery schemes taking benefit of the concentration and purification achieved along the evaporation saltwork ponds. However, the geochemistry of these elements in this environment has not been yet thoroughly evaluated. Their knowledge could enable the deployment of technologies capable to achieve the recovery of valuable minerals. The high ionic strengths expected (0.5–7 mol/kg) and the chemical complexity of the solutions imply that only numerical geochemical codes, as PHREEQC, and the use of Pitzer model to estimate the activity coefficients of the different species in solution can be adopted to provide valuable description of the systems. In the present work, for the first time, PHREEQC Pitzer code database was extended to include the target minor and trace elements using Trapani saltworks (Sicily, Italy) as a case study system. The model was able to predict: i) the purity in halite and the major impurities contained, mainly Ca, Mg and sulphate species; ii) the fate of minor components as B, Sr, Cs, Co, Ge and Ga along the evaporation ponds. The results obtained pose a fundamental step in critical raw materials mining from seawater brine, for process intensification and combination with desalination. This work was supported by the EU within SEArcularMINE (Circular Processing of Seawater Brines from Saltworks for Recovery of Valuable Raw Materials) project – Horizon 2020 programme, Grant Agreement no. 869467. This output reflects only the author's view. The European Health and Digital Executive Agency (HaDEA) and the European Commission can- not be held responsible for any use that may be made of the information contained therein. Sosalt saltworkers Giuseppe and Giovanni Culcasi are thankfully ac- knowledged for sharing their ancestral knowledge with the SEArcularMINE project. Dr. C. Ayora from IDAEA-CSIC (Barcelona, Spain) is acknowledged for his help on the review of the PHREEQC Pitzer data base completion and guidance on the modelling stage and on the discussion and results interpre- tation of the mineralogical data from the solid samples collected on the bot- tom parts of the ponds.

Pickling is one of the most important steps in steel manufacturing industry. During the process, an acid reacts with the surface oxides causing metal ions accumulation in the pickling solution. Disposal of the waste acid represents a critical issue for the hot-dip galvanizing industry in terms of environmental damage and high costs. Recovering of the main products by using an integrated process, with the perspective of a circular approach, could minimize the wastewater production, leading to reinvigorate this industrial sector economy. In this context, recovery of the metal ions mainly present in the pickling solution, such as Fe and Zn, becomes a critical issue. In this work, the reactive precipitation process reliability was proved through lab-scale experiments, in order to collect information for the design of a pilot-plant to be installed in the Tecnozinco SrL (Carini, Italy) hot-dip galvanizing plant. Experiments were carried out in a continuous stirred tank reactor by feeding the acidic metals-rich stream, an alkaline reactant and an oxidant. The quantity of Fe in the outlet solution and its speciation in the precipitate were detected to evaluate the recovery efficiency and the process quality, whereas Zn concentration in the precipitated was detected for determining the product purity. Some key parameters, such as temperature and pH, were studied by varying inlet streams flow rates. A very effective metals separation was observed by obtaining Fe(III) hydroxide at a high purity of 99 %. Zn ions were successfully separated by keeping them in solution with the aim of generating a zinc/ammonium chloride stream, to be reused in the fluxing baths of the hot-dip galvanizing plant.

Nel presente lavoro è descritto un modulo didattico sviluppato, nell’ambito del progetto europeo IRRESISTIBLE, dall’unità di Palermo sul tema dell’applicazione delle nanoscienze allo sfruttamento dell’energia solare. L’attività è stata rivolta ad alunni del biennio dell’Istituto Tecnico, nell’ambito delle discipline Scienze Chimiche Integrate e Scienze e Tecnologie Applicate Chimca e ad alunni dell’ultimo anno del Liceo Scientifico, nell’ambito della disciplina Fisica. Tra le varie attività , anche sperimentali, è stata realizzata una cella DSSC che, insieme ad altro materiale di comunicazione preparato dagli stessi studenti, è stata presentata alla mostra scientifica Esperienza inSegna e al meeting finale del progetto, che si è svolto a Kiel in Germania. Alla fine del modulo gli studenti hanno dimostrato di aver acquisito, oltre alle necessarie competenze chimiche, anche una notevole sensibilità nei riguardi del rapporto tra scienza e società con particolare riferimento nei confronti della ricerca e della innovazione responsabili. Il progetto europeo IRRESISTIBLE ha affrontato i problemi inerenti la formazione scientifica e ha avuto lo scopo di diffondere la consapevolezza delle tematiche di Ricerca e Innovazione Responsabili (RRI), promuovendo attività di formazione degli insegnanti da sperimentare in classe con l’ausilio della metodologia Inquiry-based Science Education (IBSE)

Il diossido di titanio, TiO2, ampiamente utilizzato come pigmento di colore bianco, è uno dei materiali più studiati nell’ambito della ricerca per le sue proprietà fotocatalitiche. Esso, infatti, contribuisce alla fotodegradazione di sostanze inquinanti, motivo per cui è utilizzato nel settore della purificazione dell’aria e dell’acqua e per la realizzazione di vetri autopulenti, disponibili commercialmente. Nel presente lavoro viene suggerito un percorso didattico con l’obiettivo di mettere in evidenza le proprietà fotocatalitiche del diossido di titanio oltre che può essere utilizzato per affrontare concetti fondamentali quali la struttura a bande dei solidi e la fotocatalisi. Il percorso si articola in più fasi che ricalcano quelle suggerite nei metodi didattici basati sull’indagine come il protocollo delle 5E dell’approccio IBSE. Dopo aver assistito a una dimostrazione che illustra le proprietà fotocatalitiche del diossido di titanio con l’ausilio di un opportuno pigmento, gli studenti sono guidati nell’indagine dei diversi fattori che influenzano il processo.

Recent researches have demonstrated that electrochemical methods offer an attractive alternative to traditional routes for treating wastewaters containing toxic or/and refractory organic pollutants. The effectiveness of the electrochemical treatment depends on many factors including the presence in solution of specie able to act as mediators. In particular, the effect of chloride ions on the performances of the process has been the object of numerous researches. However, up to now, many practical and theoretical aspects about this argument are not completely clear. In the present work, the anodic incineration of oxalic acid (OA) in the presence of NaCl has been investigated with the aim of studying in a systematic way the influence of numerous parameters, such as the current density, the flow rate, the OA, the NaCl concentrations and the pH on the performances of the process and to individuate the optimal operative conditions. Oxalic acid was chosen as model substrate for its low reactivity toward anodic oxidation, which also results in an incomplete mineralization of more complex organics. Furthermore, the oxidation of this simple molecule does not involve the formation of stable intermediates thus giving rise to a more easy rationalizing of experimental results. Since the effect of NaCl on the process is expected to depend on the nature of the electrodic material, two very different anodes were used: the Ti/IrO2-Ta2O5 which presents a quite low oxygen overpotential and boron doped diamond (BDD) which is probably one of the more promising materials for the electrochemical incineration.

n this work, we present the growth and electrochemical performance of nanostructured lead and lead oxide electrodes for lead-acid batteries. The electrodes were obtained by template electrodeposition in polycarbonate membranes, acting as template. Electrochemical tests were conducted at constant current in 5M aqueous solution of sulphuric acid, after assembling nanostructured lead and lead oxide electrodes in a zero-gap configuration using a commercially available separator. The main advantages of these electrodes are the high specific energy and power density, and the wide surface area, about 70 times higher than the geometrical one. These features allowed high discharge rates, up to 20C. Moreover, in comparison with commercial lead-acid batteries that usually deliver about 30 mAh/g for only 15-20 cycles at 1C rate, our batteries are able to charge and discharge at very high rate (1C and more) without decay up to 1200 cycles. Copyright © 2013, AIDIC Servizi S.r.l.

In the last years, many research groups have focused their attention on the innovative chemical processes adopted for the treatment of water effluents polluted by recalcitrant organic substances, i.e., substances resistant to biological treatment. The electrochemical oxidation is one of the most studied technologies because it presents high versatility and low cost, it is realized under mild conditions of pressure and temperature and generally it does not involve the use of toxic substances [1]. In this work, the comparative performance of different electrochemical approaches such as direct oxidation processes, oxidation by means of electrogenerated chlorine and electro-Fenton was investigated. The influence of numerous parameters, such as the nature of the electrodic material and of the organic pollutant, the pH, the flow dynamic regime, the current density, the pollutant concentration and the temperature, on the electrochemical incineration of some carboxylic acids and aliphatic chlorides, chosen as model organic compounds, was studied in detail. Two very different anodes were used: Ti/IrO2-Ta2O5, which presents a quite low oxygen overpotential, and boron-doped diamond (BDD), which certainly is one of the most promising materials for the electrochemical incineration [2,3]. Incineration of carboxylic acids was favored by high flow rate and low current density, i.e., when the oxidation process was mainly under kinetic control. Moreover, the process resulted to be favored by high initial concentrations of the organic substrate and low pH but it did not depend, under the adopted operative conditions, on the nature of the supporting electrolyte. The effect of sodium chloride on the electrochemical oxidation of oxalic acid was observed to depend on the nature of the anode as well as on the pH. The best results were achieved by using IrO2-Ta2O5 electrode, with addition of sodium chloride at acid pH. Furthermore, in the presence of high amounts of sodium chloride, a higher abatement of oxalic acid was obtained when high current densities and low flow rates were imposed. Comparing the performance of electro-Fenton process coupled with anodic oxidation at BDD anode and that of simple anodic oxidation, higher abatements of 1,2-dichloroethane and 1,1,2,2-tetrachloroethane were obtained in the first case thanks to the presence of Fe2+ in the solution. Higher applied currents led to a faster electrogeneration of H2O2 and regeneration of Fe2+, thus giving rise to a faster degradation of the starting compounds. The time course of the concentration of the main intermediates accumulated in the electrochemical cell during the treatments, particularly short-chain carboxylic acids and chlorinated ions, was also reported. [1] Jüttner K. et al., Electrochimica Acta, 45 (2000) 2575–2594. [2] Panizza M. and Cerisola G., Electrochimica Acta, 51 (2005) 191–199. [3] Martinez-Huitle C. A. and Ferro S., Chem. Soc. Rev., 35 (2006) 1324-1340.

Many electrochemical technologies, either based on novel concepts (such as microbial fuel cells), experimental setups (such as photoelectrochemical or solar photoelectro-Fenton reactors) or materials (mainly focused on the use of large O2-overpotential anodes like BDD) have been devised in recent years for water remediation. Special attention has been paid to highly toxic, biorefractory organic pollutants such as the chlorinated hydrocarbons, which conjugate toxicity with chemical stability, bioaccumulation and long-range diffusivity [1]. Electroreduction at silver cathodes becomes an interesting alternative to degrade chloro-organic compounds, but it may lead to the accumulation of reaction by-products, even upon coupling with electro-oxidation at BDD [2]. On the other hand, some Fenton-based processes have proven very effective for the destruction of organic matter due to the action of •OH formed when cathodically electrogenerated H2O2 reacts with added Fe2+ [3]. Based on this, we have envisaged a potential strategy for the enhanced removal of chloro-organic pollutants and their by-products: electro-Fenton process in the bulk upon H2O2 electrogeneration at a carbonaceous cathode, which can simultaneously act as the substrate for electroreduction at loaded Ag nanoparticles. To achieve this goal, a highly efficient material for H2O2 production, i.e., a gas diffusion electrode (GDE), has been chosen for Ag-loading experiments. Several authors have reported the preparation of Ag-loaded carbonaceous materials based on a simple electroless deposition (ELD) process from Ag+ solutions. Some of them have addressed the full preparation of GDEs with Ag catalysts [4,5]. Here, we report the use of a commercial GDE as a suitable substrate to obtain conveniently dispersed Ag nanoparticles. The effect of several ELD parameters (e.g., nature of reductant, mode of application and deposition time) on the surface morphology has been mainly studied by SEM-EDX. Bulk electrolyses in 50 mM Na2SO4 at various pH were subsequently performed with the best materials to assess their ability to electrogenerate H2O2. For comparison, carbon paper was used as an alternative substrate. An important objective of the research was to find the optimum conditions to load the substrate so as to keep the balance between covered and uncovered area, in order to favor both H2O2 production and pollutant electroreduction. The performances of these electrodes for the electrogeneration of H2O2 and the abatement of chloro-organic pollutants is currently being investigated. [1] S. Rondinini, A. Vertova, in Electrochemistry for the environment, 2010, pp. 279–306. [2] O. Scialdone, A. Galia, L. Gurreri, S. Randazzo, Electrochim. Acta 55 (2010) 701–708. [3] E. Brillas, I. Sirés, M.A. Oturan, Chem. Rev. 109 (2009) 6570–6631. [4] E. Gülzow, N. Wagner, M. Schulze, Fuel Cells 3 (2003) 67–72. [5] S. Rondinini, G. Aricci, Z. Krpetic, C. Locatelli, A. Minguzzi, F. Porta, A. Vertova, Fuel Cells 3 (2009) 253–263.

Los hidrocarburos alifáticos clorados conjugan toxicidad con una alta estabilidad química, capacidad de bioacumulación y difusión de largo alcance. Los cloroetanos son particularmente ubicuos en la industria y en los productos domésticos, y su introducción en el medio ambiente puede entrañar riesgos para los seres vivos. Actualmente, la USEPA (US Environmental Protection Agency) está llevando a cabo el llamado “Endocrine Disruptor Screening Program (EDSP)”, en el cual tanto el 1,2-dicloroetano (DCA) como el 1,1,2,2-tetracloroetano (TCA) son considerados prioritarios debido a sus efectos potenciales sobre el sistema endocrino. El DCA se encuentra también en la lista de substancias prioritarias establecida recientemente por la Comisión Europea.1 Para evitar o, cuando menos, minimizar la entrada de cloroetanos en el medio acuático es necesaria la aplicación de tecnologías de tratamiento de aguas más eficaces que las tradicionalmente empleadas en las plantas de tratamiento de aguas residuales, como por ejemplo los procesos de oxidación avanzada (AOPs). De entre éstos, los AOPs electroquímicos (EAOPs) como la oxidación anódica (OA) y el proceso electro-Fenton (EF) vienen suscitando un gran interés para la degradación de compuestos orgánicos debido a sus excepcionales características técnicas y al uso reducido de compuestos químicos de elevado coste. Sin embargo, hasta la fecha, la electrorreducción con cátodos de plata ha sido el método electroquímico más utilizado para la destrucción de cloroetanos, observándose en general una conversión parcial de los contaminantes iniciales en lugar de su mineralización total. En este trabajo, se han tratado disoluciones acuosas ácidas de DCA y TCA mediante los procesos EF y OA. Las electrólisis se han realizado a corriente constante usando un ánodo de diamante dopado con boro (BDD) y un cátodo a difusión de aire (ADE) capaz de generar H2O2 in situ, el cual reacciona con el Fe2+ añadido para obtener •OH en el seno de la disolución a partir de la conocida reacción de Fenton. A los 420 min de tratamiento EF a 300 mA, se alcanzó la mineralización prácticamente total de disoluciones con 4 mM de DCA o TCA. Tratamientos comparativos en ausencia de Fe2+ (es decir, OA) o con un ánodo de menor poder oxidante como el Pt condujeron a una mineralización más pobre. Los resultados tan positivos obtenidos mediante el proceso EF con BDD se pueden atribuir a la acción sinérgica de los radicales oxidantes, es decir, BDD(•OH) en la superficie del ánodo y •OH en el seno de la disolución, además de la minimización de las limitaciones difusivas. El descenso de la concentración del contaminante inicial se ajusta perfectamente a una cinética de pseudo primer orden. Los subproductos acumulados en mayor concentración durante la degradación del DCA y el TCA son los ácidos cloroacético y dicloroacético, respectivamente. Así mismo, se han identificado los ácidos acético, oxálico y fórmico. Los caminos de reacción propuestos incluyen etapas de decloración oxidativa y reductiva (catódica). Por otra parte, se ha encontrado que el cloro se libera inicialmente como ion Cl, el cual es oxidado a ion ClO3 y, fundamentalmente, a ion ClO4, gracias a la acción de los radicales BDD(•OH) y •OH generados en gran proporción. En conclusión, se ha demostrado que el proceso EF con una celda BDD/ADE es una tecnología muy efectiva para la descontaminación de disoluciones acuosas de DCA y TCA, así como de mezclas de ambos, lo cual constituye un resultado importante de cara a proseguir con su tratamiento en matrices de agua real. Referencias 1. European Commission, Identification of Priority Hazardous Substances under the Water Framework Directive, Directorate-General Environment, 2000.