| Cristina Minnelli, Emiliano Laudadio, Rosamaria Fiorini, Roberta Galeazzi, Tatiana Armeni, Pierluigi Stipa, Dario Rusciano, Giovanna Mobbili, “Influence of a Lipophilic Edaravone on Physical State and Activity of Antioxidant Liposomes: an Experimental and in silico Study”, Colloids and Surfaces B: Biointerfaces, Volume 210, 2022, 112217 |
| Abstract: The influence of a lipophilic derivative of Edaravone (C18Edv) on a POPC liposomal bilayer has been investigated by a combined computational-experimental approach. The order and hydration degree of three different systems composed by 10%, 20% and 40% in w/w percentage of C18Edv respect to POPC were investigated through Molecular Dynamics (MD) simulations and fluorescence spectroscopy experiments. Dynamic Light Scattering measurements showed how the presence of different amounts of C18EdV determines differences on liposome size and stability. The survey revealed that the content of lipophilic antioxidant tunes liposome rigidity and influences cellular uptake and antioxidant activity which are maximized for formulation containing 20% of C18Edv |
| G. Nava, R. Barboza, F. Simoni, O. Iadlovska, O. D. Lavrentovich, and L. Lucchetti, “Optical control of light polarization in heliconical cholesteric liquid crystals”, Optics Letters 47 (12), 2967-2970, 2022 |
| Abstract: We show here that light polarization of a beam propagating through a heliconical cholesteric cell can be controlled by tuning the Bragg resonance of the structure. We demonstrate that this control is achieved by varying either the low-frequency electric field or the intensity of a pump beam impinging on the sample. The study confirms the recently reported phenomenon of optical tuning of the heliconical cholesterics and opens the door for the development of simple and efficient polarization modulators controlled electrically or optically. |
| F. Stazi, V. Corinaldesi, Y. Capotondo, I. Porcarelli, C. Di Perna, M. D’Orazio “Effect of pore modulating additives-sepiolite and colloidal nano silica-on physical, mechanical and durability properties of lime-based renders” Materials and Structures 55:123, 2022 |
| Abstract: In hot-humid climates, porous external surfaces of the buildings with high water sorption capabilities could contribute to the surface temperatures reduction through the release of latent heat by evaporative cooling. On the other hand, compact and low permeable finishing materials could have mechanical and durability benefits respect to the underlying supports, for example reducing the permeability to degrading agents. In this paper, the properties of lime base coat renders with pore modulating additives (sepiolite and colloidal nano silica) have been surveyed to evaluate their effectiveness in water absorption, thermal performance, and the fulfilment of mechanical requirements for the application on the external side of the walls. A traditional lime–sand formulation was taken as reference. After preliminary tests on workability and shrinkage, the optimal mix designs were selected and the samples were subjected to several mechanical and thermo-hygrometric tests, before and after accelerated aging. The results allowed demonstrating that the use of sepiolite in substitution of sand, enhances the render ductility, thermal resistance and water uptake but worsens its mechanical stability, increasing the shrinkage effects and slightly reducing the ultimate strength values. The addition of colloidal nano silica, either to lime–sepiolite or to lime–sand renders, fails to produce any improvement in their either physical or mechanical behavior. Mixed formulations (lime–sand with sepiolite and nano silica) behave as simple lime–sand solutions, showing optimal compressive and flexural strength but reduced water uptake capabilities. This demonstrates that the presence of sand prevails in the performance of the render, and that the adoption of other additives doesn’t worth the cost for the benefit presented. |
| Rama, F., Busico, G., Arumi, J.L., Kazakis, N., Colombani, N., Marfella, L., Hirata, R., Kruse, E., Sweeney, P., Mastrocicco, M. “Assessment of intrinsic aquifer vulnerability at continental scale through a critical application of the drastic framework: The case of South America” Science of the Total Environment 823, (June), 2022, 153748 |
| Abstract: An assessment of the intrinsic aquifer vulnerability of South America is presented. The outcomes represent the potential sensitivity of natural aquifers to leaching of dissolved compounds from the land surface. The study, developed at continental scale but retaining regionally a high resolution, is based on a critical application of the DRASTIC method. The biggest challenge in performing such a study in South America was the scattered and irregular nature of environmental datasets. Accordingly, the most updated information on soil, land use, geology, hydrogeology, and climate at continental, national, and regional scale were selected from international and local databases. To avoid spatial discrepancy and inconsistency, data were integrated, harmonized, and accurately cross-checked, using local professional knowledge where information was missing. The method was applied in a GIS environment to allow spatial analysis of raw data along with the overlaying and rating of maps. The application of the DRASTIC method allows to classify South America into five vulnerability classes, from very low to very high, and shows an overall medium to low vulnerability at continental scale. The Amazon region, coastal aquifers, colluvial Andean valleys, and alluvial aquifers of main rivers were the areas classified as highly vulnerable. Moreover, countries with the largest areas with high aquifer vulnerability were those characterized by extended regions of rainforest. In addition, a single parameter sensitivity analysis showed depth to water table to be the most significant factor, while a cross-validation using existing vulnerability assessments and observed concentrations of compounds in groundwater confirmed the reliability of the proposed assessment, even at regional scale. Overall, although additional field surveys and detailed works at local level are needed to develop effective water management plans, the present DRASTIC map represents an essential common ground towards a more sustainable land-use and water management in the whole territory of South America. |
| Kazakis, N., Busico, G., Ntona, M. M., Philippou, K., Kaprara, E., Mitrakas, M., Bannenberg, M., Ioannidou, A., Pashalidis, I., Colombani, N., Mastrocicco, M., Voudouris, K. “The origin of Uranium in groundwater of the eastern Halkidiki region, northern Greece.” Science of the Total Environment 812 (March), 2022, 152445 |
| Abstract: Uranium (U) pollution in groundwater has become a serious problem worldwide. Even in low concentrations, U has both radiological and toxicological impacts on human health. In this study an integrated hydrogeological approach was applied to conceptualize an aquifer system, and determine the origin of U detected in the aquifer of the eastern Halkidiki region in northern Greece. Data from measurements of groundwater level and hydrochemical and stable isotope analyses of groundwater samples were applied to perform geochemical modeling and multivariate statistical analysis. The modeling and statistical analysis identified three hydrogeochemical groups within the studied hydro-system, and U(VI) as the dominant U species. The first group is linked to the deeper aquifer which is characterized by water-rock interactions with weathering products of granodiorite. In this group the dominant U species is uranyl phosphate and U concentration is 3.7 μg/L. The upper aquifer corresponds to the second hydrogeochemical group where U concentrations are mainly influenced by high concentrations of nitrogen species (NO3− and NO2−). Factor analysis further discriminated the upper aquifer into a saline coastal zone and an inland zone impacted by agricultural activities. The third hydrogeochemical group presents the highest concentration of U (up to 15 μg/L) in groundwater and corresponds to the internal aquifer system. The U within this system is triggered by the presence of Mn2+, while the long residence time of the groundwater contributes synergistically to the hydrogeochemical process. Manganese triggers U oxidation in parallel with Fe2+ precipitation that acts as a regulator of U concentration. Groundwater depletion of the upper aquifers promotes the up-coning of geothermal fluids from fault zones leading to increased concentrations of U in the mid-depth aquifers. |
| Alessandrino, L., Colombani, N., Eusebi, A.L., Aschonitis, V., Mastrocicco, M. “Testing graphene versus classical soil improvers in a sandy calcisol” CATENA 208 (January), 2022, 105754 |
| Abstract: In this study for the first time, Graphene was tested in a leaching batch experiment on a calcareous sandy soil (Calcisol) to assess its capacity to ameliorate soil’s properties in comparison with traditional soil improvers (Compost, Biochar, and Zeolites). A first set of experiments was performed in triplicates using the saturation soil extraction method (5:1 liquid–solid ratio) with deionized water as liquid phase and two different rates (minimum and maximum) of each improver. A second set of experiments (5:1 liquid–solid ratio) was performed to understand the fate of fertilizers, using the maximum amount of soil improvers and two different liquid phases: NPK solution from a synthetic fertilizer and fertigation water from a wastewater treatment plant. EC, pH, ORP and dissolved O2 were monitored daily for two weeks, and water samples were obtained at the end of the experiment to analyze DOC, major ions, and trace elements. Results showed that Graphene neither altered the physical–chemical parameters nor released nutrients and heavy metals in the solution in comparison to control and other improvers. Biochar increased EC and pH beyond recommended limits for some plants growth, while Compost released NO3– above threshold limits. Batches with the NPK solution showed NH4+ accumulation in the solute for controls, and to a less extent for Zeolites, Graphene and Biochar, while no accumulation was recorded for Compost. NH4+ accumulation was triggered by microbial N remineralization in absence of a C source. Batches with fertigation water showed NO2– accumulation in the solute due to incomplete nitrification in all the improvers and control batches, since the available C source consumed O2 that in turn hampered the nitrification process. Despite the above-mentioned limitations, Graphene performed well in comparison to the other soil improvers in reducing nutrients and metals leaching. |
| Barron, A., Sun, J., Passaretti, S., Sbarbati, C., Barbieri, M., Colombani, N., Jamieson, J., Bostick, B.C., Zheng, Y., Mastrocicco, M., Petitta, M., Prommer, H. “In situ arsenic immobilisation for coastal aquifers using stimulated iron cycling: Lab-based viability assessment” Applied Geochemistry 136 (January), 2022, 105155 |
| Abstract: Arsenic (As) is one of the most harmful and widespread groundwater contaminants globally. Besides the occurrence of geogenic As pollution, there is also a large number of sites that have been polluted by anthropogenic activities, with many of those requiring active remediation to reduce their environmental impact. Cost-effective remedial strategies are however still sorely needed. At the laboratory-scale in situ formation of magnetite through the joint addition of nitrate and Fe(II) has shown to be a promising new technique. However, its applicability under a wider range of environmental conditions still needs to be assessed. Here we use sediment and groundwater from a severely polluted coastal aquifer and explore the efficiency of nitrate-Fe(II) treatments in mitigating dissolved As concentrations. In selected experiments >99% of dissolved As was removed, compared to unamended controls, and maintained upon addition of lactate, a labile organic carbon source. Pre- and post-experimental characterisation of iron (Fe) mineral phases suggested a >90% loss of amorphous Fe oxides in favour of increased crystalline, recalcitrant oxide and sulfide phases. Magnetite formation did not occur via the nitrate-dependent oxidation of the amended Fe(II) as originally expected. Instead, magnetite is thought to have formed by the Fe(II)-catalysed transformation of pre-existing amorphous and crystalline Fe oxides. The extent of amorphous and crystalline Fe oxide transformation was then limited by the exhaustion of dissolved Fe(II). Elevated phosphate concentrations lowered the treatment efficacy, indicating joint removal of phosphate is necessary for maximum impact. The remedial efficiency was not impacted by varying salinities, thus rendering the tested approach a viable remediation method for coastal aquifers. |
| Colombani, N., “Special Issue “Salinization of Water Resources: Ongoing and Future Trends” Water 14(11), (June), 2022, 1806 |
| Abstract: All over the Earth, more and more studies have shown the effects of climate changes generated by anthropic release of greenhouse gasses on the hydrological cycle [1,2]. These have induced changes in precipitation patterns as well as changes in actual and potential evapotranspiration [3], which in turn may decrease the recharge rates towards the aquifers while increasing the surface runoff towards the oceans [4,5,6]. Within this changing framework, the salinization of water resources has been already recognized as a widespread phenomenon affecting many areas throughout the globe, especially in coastal environments [7,8,9]. The already increased demand of freshwater triggered by climate change and the consequent land use changes, has intensified the research on water resources salinization and the feasible techniques aimed at mitigating such effects, such as for example the wastewater reuse via managed aquifer recharge systems [10,11]. Recently the research efforts on the effects of climate change have seen a shift from the above ground components towards the subsurface components of the hydrologic cycle [12]. Nevertheless, substantial gaps have to be filled yet to fully understand the impact of climate change on groundwater quality and the interconnected groundwater dependent ecosystems. To tackle this complex problem holistic approaches can be employed using different techniques such as remote sensing, hydrogeological, geophysical and geochemical techniques. The different kind of acquired data can then be employed to calibrate and validate process based numerical models, which are robust tools to improve our subsurface conceptual models necessary to manage the ongoing and future water resources use. The limited understanding of the ongoing and future effects of climate change on groundwater quality has therefore motivated the conception of this Special Issue. |
| G. Toscano, V. Maceratesi, E. Leoni, P. Stipa, E. Laudadio, S. Sabbatini “FTIR spectroscopy for determination of the raw materials used in wood pellet production”, Fuel, Article number 313, 2022, 123017 |
| Abstract: The research investigates the possibility of distinguishing pellet wood fuels using infrared spectroscopy. It has been applied Attenuated Total Reflectance – Fourier Transform InfraRed (ATR-FTIR) spectroscopy, deemed an analysis technique appropriate for detecting the chemical composition of materials, to determine woody components make up a wood pellet. Considering the large quantities of this solid biofuel on the market, it is necessary to guarantee the safety and traceability aspects of the product, as its origin and source, in addition to the quality parameters indicated by the ISO 17225-2 standards. In this study, a total of 98 samples of the most common wood used for European pellet production, have been selected and collected. This set of samples include also materials coming from the wood industry, as residues of the chemical process. Through clustering analysis Principal component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) techniques applied to spectroscopic analyzer data, it has been seen that ATR-FTIR results provide information on wood pellet typology, hardwood and softwood, and pellet made by woody materials containing high quantity of chemical products like glues. |
| Q. Maqbool, G. Barucca, S. Sabbatini, M. Parlapiano, M.L. Ruello, F. Tittarelli “Transformation of industrial and organic waste into titanium doped activated carbon – cellulose nanocomposite for rapid removal of organic pollutants”, Journal of Hazardous Materials, 423, 2022, 126958 |
| Abstract: Production of cost-efficient composite materials with desired physicochemical properties from low-cost waste material is much needed to meet the growing needs of the industrial sector. As a step forward, the current study reports for the first time an effective utilization of industrial metal (inorganic) waste as well as fall leaves (organic waste), to produce three types of nanomaterials at the same time; “Titanium Doped Activated Carbon Nanostructures (Ti-ACNs)”, “Nanocellulose (NCel)”, and combination of both “Titanium Doped Activated Carbon Cellulose Nanocomposite (Ti-AC-Cel-NC)”. X-ray diffraction (XRD), transmission electron microscopy (TEM) and microanalysis (EDXS) measurements reveal that the Ti-ACNs material is formed by Ti-nanostructures, generally poorly crystalized but in some cases forming hexagonal Ti-crystallites of 15 nm, embedded in mutated graphene clouds. Micro- Fourier transform infrared spectroscopy (micro-FTIR) confirms that the chemical structure of NCel with bond vibrations between 1035 to 2917 cm−1 remained preserved during Ti-AC-Cel-NC formation. The prepared materials (Ti-ACNs, Ti-AC-Cel-NC) have demonstrated rapid removal of organic pollutants (Crystal Violet, Methyl Violet) from wastewater through surface adsorption and photocatalysis. In the first 20 min, Ti-ACNs have adsorbed ≈87% of the organic pollutants and further photocatalyzed them up to ≈96%. When Ti-ACNs are combined with NCel, their efficiency is increased of about four times. This performance originates from the adsorption by mutated graphene-like carbon and assisted photocatalysis by Ti nanostructures as well as the good supporting capacity of NCel for the homogenous Ti-ACNs distribution. |
| C. Corinaldesi, S. Canensi, L. Carugati, M. Lo Martire, F. Marcellini, E. Nepote, E, S. Sabbatini, R. Danovaro “Organic enrichment can increase the impact of microplastics on meiofaunal assemblages in tropical beach systems”, Environmental Pollution, 292, 2022, 1118415 |
| Abstract: The cumulative impact of microplastic and organic enrichment is still largely unknown. Here, we investigated the microplastic contamination, the organic enrichment and their effects on meiofaunal distribution and diversity in two islands of the Maldivian archipelago: one more pristine, and another strongly anthropized. Field studies were coupled with manipulative experiments in which microplastic polymers were added to sediments from the non-anthropized island (i.e., without organic enrichment) to assess the relative effect of microplastic pollution on meiofauna assemblages. Our results reveal that the impact of microplastic contamination on meiofaunal abundance and taxa richness was more significant in the anthropized island, which was also characterized by a significant organic enrichment. Meiofauna exposed experimentally to microplastic contamination showed: i) the increased abundance of opportunistic nematodes and copepods and ii) a shift in the trophic structure, increasing relevance in epistrate-feeder nematodes. Based on all these results, we argue that the coexistence of chronic organic enrichment and microplastics can significantly increase the ecological impacts on meiofaunal assemblages. Since microplastic pollution in the oceans is predicted to increase in the next decades, its negative effects on benthic biodiversity and functioning of tropical ecosystems are expected to worsen especially when coupled with human-induced eutrophication. Urgent actions and management plans are needed to avoid the cumulative impact of microplastic and organic enrichment. |
| M. Gasparrini, F. Mazzola, M. Cuccioloni, L. Sorci , V. Audrito, F. Zamporlini, C. Fortunato, A. Amici, M. Cianci, S. Deaglio, M. Angeletti, N. Raffaelli . “Molecular insights into the interaction between human nicotinamide phosphoribosyltransferase and Toll-like receptor 4”, Journal of Biological Chemistry, 298:101669, 2022. |
| Abstract: The secreted form of the enzyme nicotinamide phosphoribosyltransferase (NAMPT), which catalyzes a key reaction in intracellular NAD biosynthesis, acts as a damage-associated molecular pattern triggering Toll-like receptor 4 (TLR4)-mediated inflammatory responses. However, the precise mechanism of interaction is unclear. Using an integrated approach combining bioinformatics and functional and structural analyses, we investigated the interaction between NAMPT and TLR4 at the molecular level. Starting from previous evidence that the bacterial ortholog of NAMPT cannot elicit the inflammatory response, despite a high degree of structural conservation, two positively charged areas unique to the human enzyme (the α1-α2 and β1-β2 loops) were identified as likely candidates for TLR4 binding. However, alanine substitution of the positively charged residues within these loops did not affect either the oligomeric state or the catalytic efficiency of the enzyme. The kinetics of the binding of wildtype and mutated NAMPT to biosensor-tethered TLR4 was analyzed. We found that mutations in the α1-α2 loop strongly decreased the association rate, increasing the KD value from 18 nM, as determined for the wildtype, to 1.3 μM. In addition, mutations in the β1-β2 loop or its deletion increased the dissociation rate, yielding KD values of 0.63 and 0.22 μM, respectively. Mutations also impaired the ability of NAMPT to trigger the NF-κB inflammatory signaling pathway in human cultured macrophages. Finally, the involvement of the two loops in receptor binding was supported by NAMPT-TLR4 docking simulations. This study paves the way for future development of compounds that selectively target eNAMPT/TLR4 signaling in inflammatory disorders. |
| P. Forcellese, T. Mancia, M. Simoncini, T. Bellezze, “Investigation on Corrosion Resistance Properties of 17-4 PH Bound Metal Deposition As-Sintered Specimens with Different Build-Up Orientations”, Metals, Article number 588, Vol. 12(4), DOI: 10.3390/met12040588, April 2022. |
| Abstract: Additive manufacturing is a promising and emerging technology that can transform the global manufacturing and logistics by cutting costs and times of production. Localized corrosion resistance properties of 0 degrees, 45 degrees, and 90 degrees build-up orientations of 17-4 PH as-sintered samples, manufactured by means of Bound Metal Deposition (BMD), have been investigated by electrochemical and morphological investigations. The cyclic potentiodynamic polarization curves and the open circuit potential monitoring, together with potential drop analysis, revealed that the BMD localized corrosion resistance properties were lowered if compared to a wrought 17-4 PH: a characteristic anodic behavior and many drops in potential were recorded for BMD, whilst the wrought specimens presented a typical passive behavior with pitting corrosion. Morphological investigations by scanning electron microscopy and energy-dispersive X-ray analysis revealed the presence of porosities and defects, especially for the 90 degrees build-up orientation, and inclusions of SiO2. The 45 degrees build-up orientation showed the best corrosion resistance properties among all the BMD specimens, even though defects and porosities were observed, suggesting that their morphology and geometry influenced the overall corrosion behavior |
| Letícia Marin de Andrade, Carlo Paternoster, Pascale Chevallier, Sofia Gambaro, Paolo Mengucci, Diego Mantovani Surface processing for iron-based degradable alloys: A preliminary study on the importance of acid pickling Bioactive Materials 11 (2022) 166–180 https://doi.org/10.1016/j.bioactmat.2021.09.026 |
| Abstract: The formation of a heterogeneous oxidized layer, also called scale, on metallic surfaces is widely recognized as a rapid manufacturing event for metals and their alloys. Partial or total removal of the scale represents a mandatory integrated step for the industrial fabrication processes of medical devices. For biodegradable metals, acid pickling has already been reported as a preliminary surface preparation given further processes, such as electropolishing. Unfortunately, biodegradable medical prototypes presented discrepancies concerning acid pickling studies based on samples with less complex geometry (e.g., non-uniform scale removal and rougher surface). Indeed, this translational knowledge lacks a detailed investigation on this process, deep characterization of treated surfaces properties, as well as a comprehensive discussion of the involved mechanisms. In this study, the effects of different acidic media (HCl, HNO3, H3PO4, CH3COOH, H2SO4 and HF), maintained at different temperatures (21 and 60 ◦C) for various exposition time (15–240 s), on the chemical composition and surface properties of a Fe–13Mn-1.2C biodegradable alloy were investigated. Changes in mass loss, morphology and wettability evidenced the combined effect of temperature and time for all condition |
| Samira Ravanbakhsh, Carlo Paternoster, Gianni Barucca, Paolo Mengucci, Sofia Gambaro, Theophraste Lescot, Pascale Chevallier, Marc-André Fortin, Diego Mantovani. Improving the radiopacity of Fe-Mn biodegradable metals by magnetron-sputtered W-Fe-Mn-C coatings: Application for thinner stents. Bioactive Materials 12, 64-70 (2022) Q1 https://doi.org/10.1016/j.bioactmat.2021.10.022 |
| Abstract: In this exploratory work, micrometric radiopaque W–Fe–Mn–C coatings were produced by magnetron sputtering plasma deposition, for the first time, with the aim to make very thin Fe–Mn stents trackable by fluoroscopy. The power of Fe–13Mn-1.2C target was kept constant at 400 W while that of W target varied from 100 to 400 W producing three different coatings referred to as P100, P200, P400. The effect of the increased W power on coatings thickness, roughness, structure, corrosion behavior and radiopacity was investigated. The coatings showed a power-dependent thickness and W concentration, different roughness values while a similar and uniform columnar structure. An amorphous phase was detected for both P100 and P200 coatings while γ-Fe, bcc-W and W3C phases found for P400. Moreover, P200 and P400 showed a significantly higher corrosion rate (CR) compared to P100. The presence of W, W3C as well as the Fe amount variation determined two different micro-galvanic corrosion mechanisms significantly changing the CR of coatings, 0.26 ± 0.02, 59.68 ± 1.21 and 59.06 ± 1.16 μm/year for P100, P200 and P400, respectively. Sample P200 with its most uniform morphology, lowest roughness (RMS = 3.9 ± 0.4 nm) and good radiopacity (~6%) appeared the most suitable radiopaque biodegradable coating investigated in this study. |
| M. Di Sante, D. Bernardo, I. Bellezza, E. Fratalocchi, Mazzieri F., “Linking small-strain stiffness to development of chemical reactions in lime-treated soils”, Transportation Geotechnics, Volume 34, May 2022, Article number 100742. |
| Abstract: In the context of lime stabilization, this note shows how the development of soil–lime reactions can be linked to the variation of small shear stiffness with time. To determine the evolution of small-strain stiffness, the shear wave velocity was measured by means of bender elements (BE) on a compacted clayey soil treated with 3% quicklime, starting form 2 h after compaction until 98 days of curing. Different methods of signal interpretation were applied with the purpose of highlighting how the peculiarity of lime treated soils affects BE testing results and to provide practical indications for optimizing similar testing on lime-treated soils. The results showed that lime treatment and compaction affect the waveform of the received signal and that measurements should span across a wide range of input frequencies in order to identify an optimal waveform. The small strain shear modulus was found to increase with curing time with a trend that can be related to that of soil–lime chemical reactions, thus representing a promising parameter to monitor the development of soil–lime reactions. |
| Erica Gagliano, Massimiliano Sgroi, Pietro Paolo Falciglia, Claudia Belviso, Francesco Cavalcante, Antonio Lettino, Federico G.A. Vagliasindi, Paolo Roccaro, “Removal of ammonium from wastewater by zeolite synthetized from volcanic ash: Batch and column tests”, Journal of Environmental Chemical Engineering, Volume 10, Issue 3, 2022, 107539 |
| Abstract: Volcanic ash (VA) fallout during explosive activity of Mt. Etna (Sicily, Italy) negatively impacts the economy of local municipalities due to the management and disposal costs. In order to investigate an alternative use of VA in the civil and environmental engineering field, zeolites synthetized from VA were employed to remove ammonium from various aqueous solutions. Specifically, batch adsorption experiments were conducted to assess the effect of different synthesis conditions (e.g., incubation temperature, use of seawater or distilled water, VA particle size) on the adsorption capacity of ammonium on the produced zeolites. Adsorption isotherms were well fitted by Freundlich model and showed that zeolite synthetized at 70 °C using distilled water (C1H70) exhibited the highest adsorption capacity (~18.4 mg g−1). The observed ammonium adsorption capacity is higher or comparable to other natural or synthetized zeolites reported in literature. C1H70 was used in column experiments under different operational conditions, including initial ammonium concentration (10 and 40 mg L−1), empty bed contact time (EBCT, 4 and 8 min) and water quality (deionized water vs. secondary effluent wastewater). The Dose-Response model showed the best fitting in describing the breakthrough curves. Obtained results showed a good removal of ammonium even though the adsorption capacity decreased in presence of competing ions (e.g., calcium) and when tap water or wastewater was used. Moreover, the adsorption capacity of C1H70 regenerated through NaCl solution was found similar to the fresh C1H70. However, the regenerated zeolite was characterized by a slower mass transfer process. Overall, synthetized zeolites from VA can be used to remove ammonium from wastewater, reducing both the landfilling of VA and the extraction of natural zeolite under the circular economy perspective. |
