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This study combines the use of corn starch and Tetradesmus obliquus microalgae for the production of antioxidant starch films as flexible packaging material. Starch was plasticized with glycerol and blended with 1 w% polyallylamine chosen as an agent to modify the film physical properties. The addition of polyallylamine improved film water stability and water vapor transmission rate as well as mechanical stiffness and tenacity. The dried Tetradesmus obliquus microalgae, which showed an EC50 value of 2.8 mg/mg DPPH (2.2-Diphenyl-1-picrylhydrazyl radical), was then used as antioxidant filler. The addition of microalgae provided the films with good antioxidant activity, which increased with microalgae content increasing. To our knowledge, this is the first study reporting the development of sustainable bioactive packaging films composed of almost 100% starch, and follows the European union’s goals on plastics strategy concerning the promotion of bio-based, compostable plastics and the setting up of approaches to prevent food waste with a simple plastic packaging.

p-Cu2O/n-TiO2 photoanodes were produced by electrodeposition of octahedral p-type Cu2O nanoparticles over n-type TiO2 nanotubes. The photoresponse of the composite p-n photoanodes was evaluated in photoelectrochemical cells operating at "zero-bias" conditions under either visible or UV-vis irradiation. In both operating conditions, the produced electrodes invariably followed the p-n-based photoanode operations but exhibited lower photoelectrochemical performance as compared to the bare n-TiO2 photoanode under UV-vis light. The reported experimental analysis evidenced that such decreased photoactivity is mainly induced by the scarce efficiency of the nanosized p-n interfaces upon irradiation. To overcome such limitation, a restructuring of the originally electrodeposited p-Cu2O was promoted, following a photoelectrochemical post-treatment strategy. p-Cu2O, restructured in a 2D leaf-like morphology, allowed reaching an improved photoelectrochemical performance for the p-n-based photoanode under UV-vis light. As compared to the bare n-TiO2 behavior, such improvement consisted of photoanodic currents up to three times larger. An analysis of the mechanisms driving the transition from compact (∼100 nm) octahedral p-Cu2O to wider (∼1 μm) 2D leaf-like structures was performed, which highlighted the pivotal role played by the irradiated n-TiO2 NTs.

The application of deep eutectic solvents (DESs) to dissolve metal oxides in lithium-ion batteries (LIBs) recycling represents a green technological alternative to the mineral acids employed in hydrometallurgical recycling processes. However, DESs are much more expensive than mineral acids and must be reused to ensure economic feasibility of LIB recycling. To evaluate DES reusability, the role of the choline chloride-ethylene glycol DES decomposition products on metal oxides dissolution was investigated. The temperatures generally applied to carry on this DES leaching induced the formation of decomposition products that ultimately improved the ability to dissolve LIB metal oxides. The characterization of DES decomposition products revealed that the improved metal dissolution was mainly determined by the formation of Cl

A novel process is reported which produces an asymmetric supercapacitor through the complete recycling of end-of-life lithium ion batteries. The electrodic powder recovered by industrial scale mechanical treatment of spent batteries was leached and the dissolved metals were precipitated as mixed metals carbonates. Nanowires battery-type positive electrodes were produced by electrodeposition into nanoporous alumina templates from the electrolytic baths prepared by dissolution of the precipitated carbonates. The impact of the different metals contained in the electrodic powder was evaluated by benchmarking the electrochemical performances of the recovered nanowires-based electrodes against electrodes produced by using high-purity salts. Presence of inactive Cu in the nanowires lowered the final capacitance of the electrodes while Ni showed a synergistic effect with cobalt providing a higher capacitance with respect to synthetic Co electrodes. The carbonaceous solid recovered after leaching was in-depth characterized and tested as negative electrode. Both the chemical and electrochemical characterization indicate that the recovered graphite is characterized by the presence of oxygen functionalities introduced by the leaching treatment. This has led to the obtainment of a recovered graphite characterized by an XPS C/O ratio, Raman spectrum and morphology close to literature reports for reduced graphene oxide. The asymmetric supercapacitor assembled using the recovered nanowires-based positive electrodes and graphite as negative electrodes has shown a specific capacitance of 42 F g−1, computed including the whole weight of the positive electrode and recovered graphite, providing a maximum energy density of ~9 Wh kg−1 and a power density of 416 W kg−1 at 2.5 mA cm−2.

Secondary pollution from hydrometallurgical recycling of lithium ion batteries (LIBs) may affect the sustainability of the overall process. This study explores the valorisation of two LIB processing streams, namely iron-sludge and Mn-stripping effluent, as magnetic nanosized sorbents. A surfactant-autoclave synthesis route was developed to obtain CuFe2O4 from synthetic precursors. This same process was then applied to synthesise a quinary ferrite, CuCoMnNiFe2O4, from iron-sludge. Both products exhibited crystallite sizes below 20 nm. The obtained materials, given the elevated specific surface (>160 m2/g) and mesoporous structure, were tested for sorption of cations from synthetic solutions and pre-treated Mn-stripping effluent. Both materials showed preferential sorption behaviour for Mn (≈16 mg/g) versus Co, Li and Na. Mn and Co removal from the pre-treated effluent was more efficient when using the recycled material (Mn 100%, Co 70%) rather than CuFe2O4 (Mn 91%, Co 59%). Furthermore, single-phase nanocrystalline MnCoNiFe2O4 ferrites were synthesized from the two LIB streams by an ultrasound-surfactant-microwave treatment. FESEM profile width measured particle sizes of about 57 nm when the material was dried at 100 °C after synthesis and 98 nm when sintered at 700 °C. The physical and chemical properties (i.e. magnetization, porosity, sizes) of the synthesized materials were studied to assess the effects of the advanced hydrothermal routes and the starting materials on the final products.

A quantitative assessment of the material flux emerging from a pilot plant for the treatment of end-of-life photovoltaic panel waste was reported. The process included the manual dismantling of aluminum frames, mechanical treatment for size reduction, and the physical treatment of the milled materials for the release of coarse glass from the encapsulant polymer. Demonstration activities were performed using 1 ton of Si-, 1 ton of CdTe-, and 1 ton of CIGS-based photovoltaic panels (investigated separately), confirming the ability of the process to treat different photovoltaic technologies. The characterization of the input materials was performed and compared with previous literature data. The major bottleneck in the definition of an effective process option for the treatment of different panel technologies was emphasized by the high heterogeneity reported. Mass balances for the proposed process were derived by the recovered material flow. It was highlighted that in processes based on mechanical treatments, producing predominantly coarse fractions allows for the facile separation of most of the valuable components. In this perspective, the present work offers further insights into the design of recycling process to reach increased profitability/sustainability, especially considering the distributions of valuable metals in the process products.

Catalytic electroreduction of carbon dioxide represents a promising technology both to reduce CO2 emissions and to store electrical energy from discontinuous sources. In this work, electrochemical deposition of copper on to a gas-diffusion support was tested as a scalable and versatile nanosynthesis technique for the production of catalytic electrodes for CO2 electroreduction. The effect of deposition current density and additives (DAT, DTAB, PEG) on the catalysts’ structure was evaluated. The selectivity of the synthesized catalysts towards the production of CO was evaluated by analyzing the gaseous products obtained using the catalysts as cathodes in electroreduction tests. Catalyst morphology was deeply influenced by the deposition additives. Copper nanospheres, hemispherical microaggregates of nanowires, and shapeless structures were electrodeposited in the presence of dodecyltrimethylammonium bromide (DTAB), 3,5-diamino-1,2,4-triazole (DAT) and polyethylene glycol (PEG), respectively. The effect of the deposition current density on catalyst morphology was also observed and it was found to be additive-specific. DTAB nanostructured electrodes showed the highest selectivity towards CO production, probably attributable to a higher specific surface area. EDX and XPS analysis disclosed the presence of residual DAT and DTAB uniformly distributed onto the catalysts structure. No significant effects of electrodeposition current density and Cu(I)/Cu(II) ratio on the selectivity towards CO were found. In particular, DTAB and DAT electrodes yielded comparable selectivity, although they were characterized by the highest and lowest Cu(I)/Cu(II) ratio, respectively.

A fed-batch strategy is proposed to produce microalgae biomass under non-axenic heterotrophic conditions. The strategy induces the alternation of N-deplete (Glucose-replete) and N-replete (Glucose-deplete) cultivation phases by the periodic and uncoupled supply of glucose and NO3− to the culture. Cultivation of the microalga T. obliquus with this strategy reduced the ratio of the bacteria to microalgae cell concentration from 1.6, attained by conventional photoautotrophic cultivation, to 0.03. During the N-deplete phase, microalgae duplication stopped and biomass concentration increased 1.9 times, while during the N-replete phase, microalgae duplicated halving their average size and losing about 25% of their weight. The process proved to be effective under several consecutive cycles. Biomass productivity until 6.1 g/Ld and biomass concentration until 26 g/L were achieved. The results demonstrate that the proposed strategy can effectively prevent bacterial contamination, paving the way to the large scale production of microalgae biomass under non-axenic heterotrophic conditions.

The direct synthesis of high-value products from end-of-life Li-ion batteries (LIBs), avoiding the complex and costly separation of the different elements, can be reached through a competitive recycling strategy. Here, we propose the simultaneous synthesis of reduced graphene oxide (rGO) and lithium-manganese-rich (Li1.2Mn0.55Ni0.15Co0.1O2 - LMR) cathode material from end-of-life LIBs. The electrode powder recovered after LIBs mechanical pretreatment was directly subjected to the Hummers’ method. This way, quantitative extraction of the target metals (Co, Ni, Mn) and oxidation of graphite to graphene oxide (GO) were simultaneously achieved, and a Mn-rich metal solution resulted after GO filtration, owing to the use of KMnO4 as an oxidizing agent. This solution, which would routinely constitute a heavy-metal liquid waste, was directly employed for the synthesis of Li1.2Mn0.55Ni0.15Co0.1O2 cathode material. XPS measurements demonstrate the presence in the synthesized LMR of Cu2+, SO42–, and SiO44– impurities, which were previously proposed as effective doping species and can thus explain the improved electrochemical performance of recovered LMR. The GO recovered by filtration was reduced to rGO by using ascorbic acid. To evaluate the role of graphite lithiation/delithiation during battery cycling on rGO production, the implemented synthesis procedure was replicated starting from commercial graphite and from the graphite recovered by a consolidated acidic–reductive leaching procedure for metals extraction. Raman and XPS analysis disclosed that cyclic lithiation/delithiation of graphite during battery life cycle facilitates the graphite exfoliation and thus significantly increases conversion to rGO., Starting from the electrodic powder of end-of-life Li-ion batteries, lithium- manganese-rich cathode material and reduced graphene oxide were obtained.

Despite the efforts devoted to the development of new cathodic materials, cobalt-based lithium-ion batteries (LIBs) remain the first choice for many applications, turning cobalt into a critical raw material. Here, we report a method for the selective recovery of cobalt from mixed LIBs electrode materials. The method relies on the application of a green deep eutectic solvent (DES) and yields an extraction of 90% for cobalt and only 10% for nickel. A solvent extraction procedure was optimized to recover cobalt as cobalt oxalate, which was employed to produce lithium cobalt oxide cathode material. This produced cathode material delivered a discharge capacity of 150 mAh g−1 and a capacity retention between 10 and 100 galvanostatic cycles of 83%. Remarkably, the residual DES solution was reused delivering the same cobalt extraction attained using the fresh DES. Cobalt separation constitutes one of the major bottleneck during LIBs recycling, requiring costly and complex hydrometallurgical operations. The demonstrated selectivity of the implemented leaching method, along with the possibility to reuse the residual DES solution, paves the way to a green recycling alternative allowing for the reintroduction of strategic materials into the LIBs production chain.

The catalytic electroreduction of carbon dioxide represents a promising technology for the management of the energy sources and the abatement of CO2 emissions. For the industrial implementation of this process, it is required the development of a selective and stable nanostructured catalytic electrode. In this study, we evaluated the synthesis of nanostructured metallic electrodes produced by galvanostatic electrodeposition of copper onto a carbon paper support. The effects of deposition current density on morphology and catalytic properties of the electrodes were analyzed. The formation of copper nano and microstructure was observed on the external structure of the carbon paper support. Regarding the morphology, a correlation between applied current density and deposition structure was found. Electrodeposited electrodes showed a catalytic selectivity towards the production of carbon monoxide almost four times greater than copper foil electrodes. An inverse correlation between deposition current density and catalytic selectivity was observed. A decrease in the deposition current from -6 mA cm-2 to -2 mA cm−2 resulted in a doubling of the measured selectivity.

The increase in the annual flux of the end-of-life photovoltaic panels (EoL-PVPs) imposed the development of effective recycling strategies to reach EU regulation targets (i.e. 80% recycling; 85% recovery, starting from August 2018). The recycling targets in a PVP are generally glass, photovoltaic cell and metals, while no scientific paper or patent addressed polymeric fractions recycling and recovery, i.e. encapsulant polymer (EVA) and backsheet (Tedlar), starting from preliminarily milled EoL-PVPs. In the present study an optimization following the solvent treatment operation of the basic Photolife process (demonstrated at pilot scale), was proposed (lab scale) and validated (micropilot scale), focusing on polymers separation and metals recovery. The optimization was performed by testing 4 different processes. Specifically, the selectivity of the filtration operation (subsequent the solvent treatment) on polymers separation grade was evaluated, demonstrating that Tedlar can be effectively separated from EVA residues. Moreover, in comparison to the basic Photolife, a further operation was introduced treating thermally the EVA residues (containing the PV cell). The metal extraction yields highlighted the effectiveness of that strategy in comparison with direct extraction from the uncombusted EVA residues. Processing 100 Kg of crushed material, 0.03 Kg of Ag, 45.5 Kg of high value glass, 10 Kg of Al scraps and 1.2 Kg of metallic filaments can be recovered. Thanks to the optimization the recycling rate of the implemented process grew up to 82% (75% during demonstration of the basic Photolife process), while the recovery was estimated at 94%. Remarkably, these rates get over with EU Directive.

In this work, an innovative hydrometallurgical recycling route for the recovery of all the materials composing Li-MnO2 primary batteries was proposed. End-of-life batteries were mechanically treated in an innovative pilot plant where a cryogenic crushing was performed. The mechanical treatment allowed for the release of the electrodic powder contained in the batteries with the simultaneous recovery of 44 kg of steel and 18 kg of plastics from 100 kg of batteries. Electrodic powder was employed as the raw material for the synthesis of LiMnPO4 nanoparticles. To obtain the synthesis precursors, selective sequential leaching of Li and Mn was performed. Li was extracted via water washing the electrodic powder and Li2CO3 and a purity of 99% was recovered. The black mass containing Mn oxides was leached using phosphoric acid, which gave a Mn-bearing precursor solution that was directly used for the hydrothermal synthesis of LiMnPO4 nanoparticles. A preliminary materials balance of the process was presented, indicating that the proposed process should be an easy hydrometallurgical route for the recycling of primary lithium batteries. In addition, the simultaneous production of high-value-added products that could be reintroduced into the battery manufacturing chain could ensure the economic feasibility of the process.

Understanding the mechanisms of phenol production by microalgae can contribute to the development of microalgal biorefinery processes with higher economic and environmental sustainability. However, little is known about how phenols are produced and accumulate during microalgal cultivation. In this study, both extracellular and intracellular phenol production by two microalgal strains (Tetradesmus obliquus and Chlorella sp.) were investigated throughout a conventional photoautotrophic batch cultivation. The highest intracellular phenol content (10−25 mg g−1) and productivity (12–18 mg L−1 d−1) were attained for both strains in the first part of the batch, indicating a positive relation with nutrient availability and biomass productivity. Extracellular phenol production was 2–20 fold lower than intracellular phenols, but reached up to 27 mg L−1 for T. obliquus and 13 mg L−1 for Chlorella sp. The latter finding highlights relevant issues about the management of the exhausted culture medium, due to likely antimicrobial effects.

The removal of arsenic from water by adsorption is currently hindered by the elevated cost of conventional adsorbent materials. To overcome this limit, an innovative iron-coated adsorbent was produced by hydrothermal carbonization (170 °C, 30 min) of olive pomace, an inexpensive byproduct of the olive oil production. Hydrothermal carbonization experiments were performed starting from olive pomace dispersions in solutions with acidic, neutral and alkaline pH, in presence and absence of FeCl3. Acidic conditions improved the carbonization, ensuring reduced H/C and O/C ratios, and increased the adsorbent stability. However, acidic pH yielded unsatisfactory iron coating, with only 32% of the iron dissolved in the initial solution transferred to the produced hydrochar. Under alkaline pH, 96% of the iron in the feedwater was, in contrast, stably dispersed over the hydrochar surface, giving the highest maximum arsenic adsorption capacity (4.1 mg/g). However, alkaline pH promoted biomass hydrolysis, causing the loss of 60% and 87% of the total C and N, respectively, and reducing the stability of the produced hydrochar. A two-stage process was tested to overcome these issues, including hydrothermal carbonization under acidic pH with FeCl3, followed by the addition of NaOH. This process prevented biomass hydrolysis yielding a stable hydrochar. However, as compared to the one-stage alkaline synthesis, the two-stage process produced an hydrochar with reduced arsenic adsorption capacity (1.4 mg/g), indicating that biomass hydrolysis could positively influence hydrochar adsorption characteristics, possibly by increasing the specific surface area. Indications are then provided on how to optimize the two-stage process in order to produce a hydrochar with both satisfactory stability and arsenic adsorption capacity.

Hydrothermal carbonization (HTC) is a promising technology for producing char material (hydrochar) from waste biomass. In the present work, a two-stage process was applied and optimized to obtain a composite Fe-loaded hydrochar effective in removing arsenic from water. The first stage of carbonization of the biomass in acid conditions was followed by loading Fe3O4 in the second stage into the hydrochar by alkaline co-precipitation. The effect on the kinetics and on the final yield of HTC induced by a variation of the initial acid pH (5.6, 2.0, and 0.5) was tested. Biomass hydrolysis initially decreased the hydrochar yield and released soluble organic species, responsible for the observed pH variation. This effect was more remarkable at the lower initial pH tested. Soluble organic compounds eventually underwent polymerization, with secondary char formation, an inversion of the pH trend and an increase of hydrochar yield and C%. The final pH attained was linearly related to the hydrochar C%, O/C ratio, and initial pH. Better carbonization performances were achieved at pH = 0.5, 200 °C, and 30 min reaction time, which resulted in 53% mass yield and 72 C%. This value is larger than those previously reported for processes conducted at higher temperatures, and it shows how the addition of acid allows working at lower operative temperatures. Fe loading gave better yields at lower hydrochar concentrations, producing an adsorbent with up to 74% Fe3O4, which adsorbed 2.67 mg/g arsenic. Its adsorption capacity was remarkably affected by the stirring method used, indicating that particle-to-particle interactions considerably influence the process. This effect should be better studied for improved applications in fixed-bed columns.

Much of our current knowledge of microbial growth is obtained from studies at a population level. Driven by the realization that processes that operate within a population might influence a population's behavior, we sought to better understand Tetradesmus obliquus (formerly Scenedesmus obliquus) physiology at the cellular level. In this work, an accurate pretreatment method to quantitatively obtain single cells of T. obliquus, a coenobia-forming alga, is described. These single cells were examined by flow cytometry for triacylglycerol (TAG), chlorophyll, and protein content, and their cell sizes were recorded by coulter counter. We quantified heterogeneity of size and TAG content at single-cell level for a population of T. obliquus during a controlled standard batch cultivation. Unexpectedly, variability of TAG content per cell within the population increased throughout the batch run, up to 400 times in the final stage of the batch run, with values ranging from 0.25 to 99 pg · cell-1 . Two subpopulations, classified as having low or high TAG content per cell, were identified. Cell size also increased during batch growth with average values from 36 to 70 μm3 · cell-1 ; yet cell size variability increased only up to 16 times. Cell size and cellular TAG content were not correlated at the single-cell level. Our data show clearly that TAG production is affected by cell-to-cell variation, which suggests that its control and better understanding of the underlying processes may improve the productivity of T. obliquus for industrial processes such as biodiesel production.

The influence of Ca2+ concentration on the growth of the microalga Scenedesmus sp. in heterotrophic and photoautotrophic cultivations was investigated. Heterotrophic growth was induced by the addition of olive mill wastewaters (9% v·v-1) to the culture. Variations in the calcium concentration affected differently biomass production depending on whether microalgae were cultivated under heterotrophic or photoautotrophic regime. In photoautotrophic regime, increasing the calcium concentration from 20 to 230mg⋅L-1 decreased maximum cell concentration and growth rate. In heterotrophic cultivation, cell concentration and growth rate decreased with Ca2+ concentration increasing from 20 to 80mg⋅L-1 but then increased with Ca2+ concentration increasing to 230mg⋅L-1. Increasing calcium concentration invariably promoted cell aggregation. The precipitation of calcium phosphates can explain the decreasing growth rate and cell concentration attained with increasing calcium concentration, while the influence of Ca2+ concentration on the adsorption of phenols on suspended solids can explain the enhanced growth attained at large Ca2+ concentration under heterotrophic regime. Implications of the illustrated results for industrial scale application of microalgae are thoroughly discussed.

The electrodeposition of cobalt nanowires into nanoporous alumina templates produced by one-step anodization of low-purity aluminium was investigated. Aluminium was electropolished prior anodization to generate a hexagonal cell pattern, and a tree-like structure was introduced at the aluminium/aluminium oxide interface by progressively decreasing the anodization potential following potentiostatic anodization. Pulsed electrodeposition including the periodic application of a cathodic potential pulse with constant amplitude was performed to fill the generated alumina template by cobalt nanowires. With this strategy, cathodic potential pulses with amplitude lower than −5 V (vs. Ag/AgCl) were necessary to enforce uniform and instantaneous cobalt nucleation at the bottom of template nanopores, which allowed achieving uniform filling and narrow length distribution of the electrodeposited nanowires. However, the uniform growth of the nucleating cobalt nanowires could be sustained by considerably less cathodic potential pulses (up to −1.5 V vs. Ag/AgCl). Uniform filling of the alumina template could accordingly be achieved by a two-stage-pulsed electrodeposition strategy including the application of a high cathodic pulse ( −1.5 V) sustaining nanowire growth. The mechanisms that govern cobalt nucleation at the bottom of nanopores and the technical advantages of the proposed nanowire synthesis strategy are discussed.

Experimental results of leaching tests using waste fractions obtained by mechanical pretreatment of lithium ion batteries (LIB) were reported. Two physical pretreatments were performed at pilot scale in order to recover electrodic powders: the first including crushing, milling, and sieving and the second granulation, and sieving. Recovery yield of electrodic powder was significantly influenced by the type of pretreatment. About 50% of initial LIB wastes was recovered by the first treatment (as electrodic powder with size0.5mm, Sample 1), while only 37% of powder with size1mm (Sample 2) can be recovered by the second treatment. Chemical digestion put in evidence the heterogeneity of recovered powders denoting different amounts of Co, Mn, and Ni. Leaching tests of both powders were performed in order to determine optimized conditions for metal extraction. Solid/liquid ratios and sulfuric acid concentrations were changed according to factorial designs at constant temperature (80°C). Optimized conditions for quantitative extraction (99%) of Co and Li from Sample 1 are 1/10g/mL as solid/liquid ratio and +50% stoichiometric excess of acid (1.1M). Using the same solid/liquid ratio, +100% acid excess (1.2M) is necessary to extract 96% of Co and 86% of Li from Sample 2. Best conditions for leaching of Sample 2 using glucose are +200% acid excess (1.7M) and 0.05M glucose concentration. Optimized conditions found in this work are among the most effective reported in the literature in term of Co extraction and reagent consumption.

An empirical model for prediction of microalgal growth in outdoor photobioreactors cultivation, using Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression method, is implemented. Experimental data of biomass production were collected over 1 year of operation of a bubble column prototype, monitoring light and temperature and changing cultivation's conditions. PCA isolates 2 Principal Components that explain 80% of the variance and are associated with Environmental Conditions and Cultivation Conditions. Moreover, the PLS regression model showed positive results in term of responses (R2 = 0.84) and residuals, following the experimental trends of outputs as specific growth rate (μ(d−1)) and productivity calculated at Cmax (Pmax (g L−1 d−1)), giving also good prediction results in its validation test. This method could be easily used for other purpose, by changing the input values of the specific cultivation used (including CO2 uptake or wastewater dilution ratio in the culture medium), obtaining as outputs the desired variables (lipid production rate, etc.).

Cobalt-based nanoparticles directly synthesized on conductive substrates through electrodeposition find application in a broad range of scientific and technological fields.The capability to characterize both morphological parameters (e.g., shape, size, structure, and numerical density per unit of area) and magnetic properties (e.g., magnetic moment, saturation magnetization, or coercivity) directly on the substrate on which they are grown is fundamental for many of those applications. In this work, we report on the use of magnetic force microscopy (MFM) to characterize Co-based nanoparticles synthesized through electrodeposition on Al substrates using two different counter electrodes, i.e., Co and Pt. Morphological analysis using AFM and scanning electron microscopy (SEM) was used to assess differences in size and number density of the nanoparticles obtained using the two counter electrodes, while MFM was employed to measure the remanent magnetization of single isolated nanoparticles, to asses the presence of a nonmagnetic shell on the nanoparticles and to estimate their thickness.

The present work is aimed at demonstrating the potentiality of lithium ion batteries recycling through the production of high added value nanostructured material. Nanostructured electrodic materials were synthesized starting from waste lithium ion batteries (LIBs). Firstly, the metals contained in the electrodic powder of exhausted LIBs were extracted by acid-reducing leaching. After filtration, metals rich solution was separated from graphite. Nanoparticles- based electrodes were produced by controlled precipitation and subsequent calcination of metals in order to obtain nanoparticles of LiNi1/3Co1/3Mn1/3O2, one of the most employed LIBs cathodic material. Cathodic materials synthesized starting from waste LIBs and from high grade synthetic reagents were compared after their characterization by SEM, EDX and XRD. The electrochemical performance of the electrodes was evaluated by galvanostatic cycling the electrodes in a lithium half-cell. Remarkably, the electrochemical performances obtained with the electrodes produced by the recovery of metals are close to those recorded using electrodes produced by synthetic reagents.

In this contribution we report on electrochemical approaches in TiO2 based electrodes synthesis. TiO2 nanotubes (NTs) were synthesized following a facile anodization of titanium sheets. Optimizing the experimental conditions two electrodes with NTs lengths of ∼10 μm (Long) and ∼2 μm (Short), were obtained. At the end of the anodization the amorphous TiO2 (a-TiO2) was thermally treated to promote the conversion in the anatase crystal phase (c-TiO2). Both the Long and Short NTs electrodes were tested for their applications as anodes in lithium-ion batteries (LIBs). A preliminary comparison was performed to evaluate the role of a-TiO2 and c-TiO2 phases. Here, Short a-TiO2 NTs exhibited a fast storage rate respect to Short c-TiO2. Comparing the NTs length, Long a-TiO2 electrodes exhibited the highest specific capacity, close to the theoretical value. Furthermore, all the electrodes tested showed an excellent capacity retention proceeding with Discharge/Charge cycles.

Biotechnologic processes based on microalgae cultivations have had an increasing interest from the early 2000s. Microalgae are microorganisms able to produce and accumulate a large variety of industrially relevant compounds starting from renewable and cheap resources. However, 3–10 € per kg of dry biomass is the minimum cost for microalgae biomass production that has been estimated by different studies published in 2016. This high cost restricts industrial applications only to the production of high-value products. The new strategies that are being investigated by scientific research to improve economic and environmental sustainability of microalgae biomass production will be described in this chapter.