Preparation and characterization of an electrospun PLA-cyclodextrins composite for simultaneous high-efficiency PM and VOC removal

Electrospinning is known to be a facile and effective technique to fabricate fibers of a controlled diameter-distribution. Among a multitude of polymers available for the purpose, the attention should be addressed to the environmentally compatible ones, with a special focus on sustainability. Polylactic acid (PLA) is a widespread, non-toxic polymer, originating from renewable sources and it can degrade into innocuous products. While the production of fibrous membranes is attractive for airborne particles filtration applications, their impact on the removal of gaseous compounds is generally neglected. In this study, electrospun PLA-based nanofibers were functionalized with cyclodextrins, because of their characteristic hydrophobic central cavity and a hydrophilic outer surface, in order to provide adsorptive properties to the composite. The aim of this work is to investigate a hybrid composite, from renewable sources, for the combined filtration of particulate matter (PM) and adsorption of volatile organic compounds (VOCs). Results show how their inclusion into the polymer strongly affects the fiber morphology, while their attachment onto the fiber surface only positively affects the filtration efficiency

The critical raw materials issue between scarcity, supply risk, and unique properties

ABSTRACT: This editorial reports on a thorough analysis of the abundance and scarcity distribution of chemical elements and the minerals they form in the Earth, Sun, and Universe in connection with their number of neutrons and binding energy per nucleon. On one hand, understanding the elements’ formation and their specific properties related to their electronic and nucleonic structure may lead to understanding whether future solutions to replace certain elements or materials for specific technical applications are realistic. On the other hand, finding solutions to the critical availability of some of these elements is an urgent need. Even the analysis of the availability of scarce minerals from European Union sources leads to the suggestion that a wide-ranging approach is essential. These two fundamental assumptions represent also the logical approach that led the European Commission to ask for a multi-disciplinary effort from the scientific community to tackle the challenge of Critical Raw Materials. This editorial is also the story of one of the first fulcrum around which a wide network of material scientists gathered thanks to the support of the funding organization for research and innovation networks, COST (European Cooperation in Science and Technology).info:eu-repo/semantics/publishedVersio

Microstructural Features in Multicore Cu–Nb Composites

none5siThe study is devoted to heavily drawn multicore Cu–18Nb composites of cylindrical and rectangular shapes. The composites were fabricated by the melt-and-deform method, namely, 600 in situ rods of Cu–18%Nb alloy were assembled in a copper shell and cold-drawn to a diameter of 15.4 mm (e = 10.2) and then rolled into a rectangular shape the size of 3 × 5.8 mm (e = 12.5). The specimens were analyzed from the viewpoints of their microstructure, microhardness, and thermal stability. The methods of SEM, TEM, X-ray analysis, and microhardness measurements were applied. It is demonstrated that, at higher strain, the fiber texture ⟨110⟩Nb∥ ⟨111⟩Cu∥ DD (drawing direction), characteristic of this material, becomes sharper. The distortions of niobium lattice can be observed, namely, the {110} Nb interplanar distance is broadened in longitudinal direction of specimens and compacted in transverse sections. The copper matrix lattice is distorted as well, though its distortions are much less pronounced due to its recrystallization. Evolution of microstructure under annealing consists mainly in the coagulation of ribbon-like Nb filaments and in the vanishing of lattice distortions. The structural changes in Nb filaments start at 300–400 °C, then develop actively at 600 °C and cause considerable decrease of strength at 700–800 °C.openElena N. Popova, Irina L. Deryagina,Evgeniya G. Valova-Zaharevskaya, Ruello Maria Letizia, Vladimir V. PopovElena N., Popova; Irina L., Deryagina; Evgeniya G., Valova-Zaharevskaya; Ruello, Maria Letizia; Vladimir V., Popo

Innovative hydraulic lime-based finishes with unconventional aggregates and TiO2 for the improvement of indoor air quality

This paper reports a study on 8 unconventional hydraulic lime-based mortars able to improve indoor air quality by acting as passive systems. Mortars have been prepared with commercial sand or highly adsorbent materials as aggregates with/without TiO2 as photocatalytic agent, to test also the decomposition of airborne pollutants. Mechanical properties, hygrometric behavior, inhibition of growth of molds and depollution properties have been tested. Despite using porous materials (zeolite and activated carbon), in mortars with unconventional aggregates, compressive strength is higher than in sand-based ones, with a more than double higher water vapor permeability. Zeolite-based mortars have the highest moisture buffering capacity followed by silica gel- and activated carbon-based mortars (1.5–2 times higher than reference, respectively, because of the high porosity of unconventional aggregates). Sand-based mortars show optimum inhibitory capacity against fungal growth. Concerning unconventional aggregates, silica gel mortars have good inhibitory capacity, whereas zeolite and activated carbon give to mortars an optimum substrate for molds. Mortars with unconventional aggregates as silica gel remove more than 80% of tracer pollutant after 2 h of test, whereas zeolite-based mortars remove the 65% of it after 120 min. TiO2 enhances depollution properties as photocatalytic oxidation agent when the mortar is close to saturation

Assessment of Potential Nutrient Release from Phosphate Rock and Dolostone for Application in Acid Soils

This is the accepted manuscript of the following article: Rafael, R. B. A., Fernández-Marcos, M. L., Cocco, S., Ruello, M. L., Weindorf, D. C., Cardelli, V., and Corti, G. (2018). Assessment of Potential Nutrient Release from Phosphate Rock and Dolostone for Application in Acid Soils. Pedosphere 28, 44-58. doi: 10.1016/S1002- 0160(17)60437-5Finding alternative local sources of plant nutrients is a practical, low-cost, and long-term strategy. In this study, laboratory column experiments were conducted in a completely randomized design to evaluate the feasibility of using phosphate rock and dolostone as fertilizers or acid-neutralizing agents for application in tropical acid soils. The dissolution rates of different particle-size fractions (0.063–0.25, 0.25–0.5, and 0.5–2 mm) of both rocks were studied by citric acid solution at pH 4 and 2 and water, with extraction times of 1, 3, 5, 7, 12, 24, 72, 144, 240, and 360 h. The results showed that the dissolution of both rocks depended on the particle size, leaching solution, and extraction time. The dissolution rate of rock-forming minerals increased as the specific surface area increased, corresponding to a decrease in particle size. In all cases, the release kinetics was characterized by two phases: 1) a first stage of rapid release that lasted 24 h and would ensure short-term nutrient release, and 2) a second stage of slow release after 24 h, representing the long-term nutrient release efficiency. Both rocks were suitable as slow-release fertilizers in strongly acid soils and would ensure the replenishment of P, Ca, and Mg. A combination of fine and medium particle-size fractions should be used to ensure high nutrient-release efficiency. Much work could remain to determine the overall impact of considerable amounts of fresh rocks in soilsThis study was mainly supported by the “Applied Research and Multi-sectorial Program” (FIAM) (No. 5.2.1) granted by the Italian Cooperation and Development Agency (ICDA) to the Universidade Eduardo Mondlane. The authors also acknowledge the Polytechnic University of Marche, Italy for the PhD scholarship provided to the first author as well as research funding for this workS

Design and Calibration of an Organic Diffusive Probe to Extend the Diffusion Gradient Technique to Organic Pollutants

The objective of this study was to develop a method for measuring the mobility of persistent organic pollutants in the solid phase of soils within the context of environmental pollution risk assessment. A new diffusive probe, purposely designed by adapting the diffusive gradient technique method, measures labile organic species by immobilizing them after diffusion through a thin deionized water layer. The measure of the mass accumulated is used to calculate the flow of pollutant from solid phase to pore water. Naphthalene was chosen as a model persistent organic pollutant. The probe was calibrated at different temperatures and was then tested in several microcosms at different porosity and reactivities with naphthalene (one clay soil, two sandy soils and one natural soil). The probe response showed good agreement with the expected different abilities of the solid phases in restoring the solution phase. The concentration of naphthalene in the pore water was well buffered by rapid equilibria with the solid phase in the investigated natural soil. In contrast, pore water concentration in the sandy soils decreased rapidly and the flow was slackened, especially for the sandy soil with finer particles. In clay, only a fraction of the total naphthalene content was present in the labile fraction, while the remaining was tightly bound and was not released to the pore water. Therefore, this first stage of testing points out that the diffusive gradient technique, if optimized, can properly quantify the mobility of organic pollutants in soil

Indoor Air Quality: A Bibliometric Study

What are the actual trends in Indoor Air Quality (IAQ), and in which direction is academic interest moving? Much progress has been made in identifying and mitigating indoor pollutants, due to both prevention campaigns (e.g., smoking bans) and greater control of product emissions. However, IAQ is still of interest and the future trends are unknown. In this study, a thorough bibliometric analysis was conducted on the scientific literature available on the Web of Science database with CiteSpace from 1990 until today. It was possible to identify past trends and current advances, both with the aim of introducing the IAQ topic to those encountering it for the first time and to examine the issues that are expected to be pertinent in the future

Enhancing landfill gas production through the management of waste water sludge disposal

This paper presents findings from short-term monitoring at full-scale municipal solid waste (MSW) landfill performed after disposal of raw biological sludge from a municipal wastewater treatment plant. Data from a landfill site located in mid-Adriatic region of Italy were evaluated as part of this study. One older landfill cell, Area B (taken as a control cell) was compared with Area C (closed cell used for the sludge disposal), for assessing the enhancing potential for gas production. Overall the results obtained pointed to positive effects (i.e., more rapid gas generation and wasted sludge degradation) realized either increasing moisture availability in the cell with respect to the measured behaviour of the traditionally operated (i.e., drier) landfill cell either providing readily biodegradable organic matter. Significant behavioural differences between the test cells were evident, including the total landfill gas production and the extent of waste degradation observed

Characterization of Wasted Wash-Stone for a Possible Re-Use in Construction Materials

Wasted wash-stone, based on pumice and expandable clay, deriving from textile treatment in industrial laundries is generally land-filled. It is also well known that natural pumice is used as aggregate for manufacturing light-weight concrete. The use of light-weight concrete is becoming more and more relevant due to its lightness and thermal-acoustic insulation properties in accordance with sustainable building principles. The possibility of replacing natural pumice with wasted wash-stone of laundries could lead to a decrease in the waste flux to disposal, to exempt companies from the related taxes and to a reduction in the extraction of non-renewable raw materials from quarries. The results obtained in this work show that the properties of the characterized wasted wash-stone are comparable with those of a commercial pumice used as aggregate to manufacture light-weight concretes. The main negative characteristics of the analyzed samples, in view of a possible re-use as aggregate in concrete, are the low reproducibility and the significant presence of organic substances (congruent to 8%) which could slow down the set time and the hardening process of the cementitious materials. However, the problem could be overcome by changing the sampling point of the waste material in the processing cycle before disposal

Electroadsorptive Removal of Gaseous Pollutants

Adsorption is a consequence of surface energy distribution, and the existence of electrostatic bonding suggests that the presence of an external electric field may affect adsorbate/adsorbent interactions. Nevertheless, this aspect has been poorly studied in the literature, except under non-thermal plasma or corona discharge conditions. After having demonstrated in our previous work that the adsorption kinetics of gaseous organic compounds can be enhanced by the presence of an external applied electric field, in this study, we focus on the influence of the electric field on adsorbent and adsorptive interactions. By using a commercially available activated carbon cloth, in addition to increasing the adsorbent mass transfer coefficient by virtue of the increasing intensity of the applied electric field, the results suggest that adsorbent morphology is only influenced by the formation of new surface functional groups. Moreover, enhanced adsorption kinetics and capacity may result from the electrohydrodynamic force induced by the movement of charged and neutral particles towards the adsorbent, as confirmed by the reversibility of the process. Such enhancement results in a negligible increase, of about 3%, in adsorption capacity (i.e., from 91 mmol m−2 Pa−1 for only adsorption to 94 mmol m−2 Pa−1 in the presence of the applied electric field), but also in a dramatic doubling of adsorption kinetics (i.e., from 0.09 min−1 for only adsorption to 0.19 min−1 in the presence of the applied electric field). In reality, the application of an electric field to an activated carbon cloth leads to faster adsorption kinetics, without substantially altering its adsorption capacity