Development and validation of an eco-compatible UV-Vis spectrophotometric method for the determination of Cu2+ in aqueous matrices.

Cu2+ are ubiquitous ions in the ecosystem and are responsible of serious environmental pollution. Indeed, the development of sensitive methods for Cu2+ detection is an urgent demand. In this work, we proposed a new spectrophotometric method for Cu2+ determination in different water matrices (distilled water, drinking water, wastewater, and river water). The method employs a bio-based organic ligand namely tetrasodium iminodisuccinate (IDS) able to form a stable complex with the analyte with a maximum absorption at 710 nm. Within the linear range of 6.3-381 mg L-1, the limit of detection (LOD) was determined to be as 1.43 mg L-1. Moreover, the recovery data of the spiked analysis of drinking/river/wastewater water samples were also satisfactory and verified the feasibility of the method for the analysis of Cu2+ in natural conditions. Finally, the AGREE assessment tool was used for a quantitative evaluation of the proposed method and reference method, in agreement with the green analytical chemistry principles. The results showed the lower environmental impact of the proposed method and the suitability of this novel approach for Cu2+ in water matrices.

Air quality evaluation during COVID-19 in Southern Italy: the case study of Avellino city.

The present study relies on the air quality evaluation during COVID-19 pandemic in Avellino, described in the last years and for several consecutive years, among the worst Italian cities in this context. The main purpose of this manuscript was to investigate the effects of quarantine and lockdown measures on air pollution. The concentrations of the main atmospheric pollutants (Carbon monoxide (CO), Ozone (O3), Fine Particulate (PM2.5 and PM10), Benzene (C6H6) and Nitrogen dioxide (NO2) were recorded during the period January-December 2020 using two stationary monitoring stations (AV1 and AV2) of the Regional Environmental Protection Agency (ARPAC). During the lockdown period (March 9-May 18, 2020), results indicated significant reductions only in the levels of CO, benzene and NO2, while for PM10 the limit of 50 µg m-3 was passed 8 times for AV1 and 13 times for AV2. The results showed the not predominant role of traffic on air quality in Avellino regards to PM levels and make it necessary a serious reflection about important and not extendable decisions to improve the air quality.

Determination of the 13C/12C Carbon Isotope Ratio in Carbonates and Bicarbonates by 13C NMR Spectroscopy.

This paper is the first study focused on the innovative application of 13C NMR (nuclear magnetic resonance) spectroscopy to determine the bulk 13C/12C carbon isotope ratio, at natural abundance, in inorganic carbonates and bicarbonates. In the past, 13C NMR spectroscopy (irm-13C NMR) was mainly used to measure isotope ratio monitoring with the potential of conducting 13C position-specific isotope analysis of organic molecules with high precision. The reliability of the newly developed methodology for the determination of stable carbon isotope ratio was evaluated in comparison with the method chosen in the past for these measurements, i.e., isotope ratio mass spectrometry (IRMS), with very encouraging results. We determined the 13C/12C ratio of carbonates and bicarbonates (∼50-100 mg) with a precision on the order of 1‰ in the presence of a relaxation agent, such as Cr(acac)3, and CH313COONa as an internal standard. The method was first applied to soluble inorganic carbonates and bicarbonates and then extended to insoluble carbonates by converting them to Na2CO3, following a simple procedure and without observing isotopic fractionation. Here, we demonstrate that 13C NMR spectroscopy can also be successfully adopted to characterize the 13C/12C isotope ratio in inorganic carbonates and bicarbonates with applications in different fields, such as cultural heritage and geological studies.

Bactericidal and Fungicidal Activity in the Gas Phase of Sodium Dichloroisocyanurate (NaDCC).

Sodium dichloroisocyanurate (NaDCC) is usually employed as a disinfectant for the treatment of water, environmental surfaces and medical equipment principally for its effectiveness as a microbicide agent. In this study, we explore the possibility of a new use for NaDCC by investigating the microbicidal activity of chlorine, which derives from the hydrolysis of NaDCC mediated by air humidity, and by testing its effect on the neutralization of microbes present in domestic waste. NaDCC was inserted in a plastic garbage can where LB agar plates, with different dilutions of a known title of four different microorganisms (Escherichia coli, Staphylococcus aureus, Debaryomyces hansenii and Aspergillus brasiliensis), were weakly inserted. The molecular chlorine (Cl2) levels present in the garbage can were quantified using an iodometric titration. The gas emitted in the garbage can presented a strong microbicide effect, inhibiting the proliferation of all four microorganisms and for four consecutive weeks, thus showing that NaDCC hydrolysis, mediated by air humidity, is able to ensure the decontamination of restricted environments, avoiding the proliferation of both Gram-positive and Gram-negative bacteria as well as fungi.

Glycerol carbonate and solketal carbonate as circular economy bricks for supercapacitors and potassium batteries.

Considering the worldwide market of batteries and supercapacitors, the (partial or total) replacement of conventional fossil-derived carbonates with bio-based ones in electrolyte formulations would allow the production of safer and more sustainable devices. In this work, embracing the 7th principle of green chemistry, glycerol derivatives (namely glycerol carbonate and solketal carbonate) are tested as solvents and additives for electrolyte formulations. Glycerol carbonate is innovatively employed as promising electrolyte solvent for electric double-layer capacitors with excellent performances. On the other hand, a solketal carbonate-laden liquid electrolyte is investigated for potassium-based batteries, showing a rather stable electrochemical behaviour and performance close to those of commercial oil-derived alternatives.

Experimental and theoretical studies on the acetaldehyde reaction with (+)-catechin.

Acetaldehyde plays a key role in determining some wine properties. Interesting is the reaction of acetaldehyde with flavonoids, as the ensuing products can alter wine color, astringency, colloidal stability. Many studies reported on the formation of ethylidene-bridged flavan-3-ols as products of the reaction between acetaldehyde and either (+)-catechin or (-)-epicatechin. In white wines after one year of incubation with acetaldehyde only vinyl-(+)-catechin and vinyl-(-)-epicatechin were observed, while no ethylidene linked oligomers were detected. This observation prompted us to study the reaction of (+)-catechin with acetaldehyde in wine model solution through an experimental and theoretical approach, with the purpose of exploring the nature of the species involved along with the mechanisms leading to them. The products of the reaction were observed over 38 days. The results showed that ethylidene-bridged catechins are the first products to be formed but over time the dissociation of these dimers causes vinyl-catechins to accumulate.

Sulphurous air pollutants and exposure events of workers in thermal-mineral springs: a case study of Contursi Terme (Salerno, Italy).

Thermo-mineral springs are widely spread over the volcanic areas of Salerno, a city in southern Italy. Although the water of thermal structures provides beneficial effects on human health, the air is characterized by the presence of potentially toxic compounds, such as hydrogen sulphide (H2S) and sulphur dioxide (SO2). Exposure to sulphurous compounds may have detrimental effects on human health, with asthma being the most common. In this study, air concentrations of H2S and SO2 in the thermal springs of Contursi Terme (Salerno, Italy) were monitored for 4 months (using both active and passive sampling), along with the chemical and microclimatic characterization of thermal water, to assess workers' exposure to these pollutants. An in-depth characterization of indoor air at the springs is paramount to establish emission control limits for occupational exposure and to take protective measures. The air concentration of SO2 varied from 0.11 ± 0.02 to 0.91 ± 0.02 mg/m3, following a seasonal pattern (higher values in winter and lower in spring). Conversely, indoor H2S concentrations did not vary significantly with time, but outdoor levels (from 0.40 ± 0.03 to 1.90 ± 0.03 mg/m3) were always higher than indoor ones (from 0.11 ± 0.03 to 0.56 ± 0.03 mg/m3). Not negligible air concentrations of these pollutants were detected in this thermal spring workplace, so further investigations are needed to ensure workers' safety.

Synthesis of Zeolitic Imidazolate Framework-8 Using Glycerol Carbonate.

In this study, we show that glycerol carbonate (GlyC), a bio-based derivative of glycerol, can be used as a suitable green solvent for the synthesis of metal-organic frameworks (MOFs). In particular, a zinc-based zeolitic imidazolate framework-8 (ZIF-8) was synthesized by exploring several different experimental conditions (in terms of temperature, reaction time, and reactants' concentrations) to find that the yield of the reaction and the quality of the products, measured in terms of crystallinity, surface area, and porosity, were in line with those obtained in the most commonly (non-green) used solvents. GlyC was also found to be reusable for several cycles, maintaining the same original quality as a solvent for the synthesis. Finally, some indicators for the assessment of the greenness of a process (E-factor and PMI) revealed a milder environmental impact of GlyC with respect to other solvents.

The Impact of Meteorological Conditions and Agricultural Waste Burning on PM Levels: A Case Study of Avellino (Southern Italy).

In this work, the effect of the meteorological conditions and the agricultural waste burning on PM air pollution levels has been investigated in the city of Avellino, located in the Sabato Valley (southern Italy). Avellino has been described among the most polluted towns in Italy in terms of particulate matter (PM) during the last 10 years. The main aim of this study was to analyze the air quality data collected in Avellino and its surroundings during September 2021. In this period, the air quality in the Sabato Valley has been adversely affected by agricultural practices, which represent a significant source of PM. The impact of agricultural waste burning on PM levels in Avellino has been determined through an integrated monitoring network, consisting of two fixed urban reference stations and by several low-cost sensors distributed in the Sabato Valley. In the considered period, the two reference stations recorded several exceedances of the daily average PM10 legislative limit value (50 µg m-3) in addition to high concentrations of PM2.5. Moreover, we provide a detailed description of the event that took place on 25 September 2021, when the combined effect of massive agricultural practices and very stable atmospheric conditions produced a severe pollution episode. Results show PM exceedances in Avellino concurrent with high PM values in the areas bordering the city due to agricultural waste burning and adverse meteorological conditions, which inhibit PM dispersion in the atmosphere.

Leonardo da Vinci's "Last Supper": a case study to evaluate the influence of visitors on the Museum preservation systems.

The most important parameter to obtain an appropriate preservation condition of museum environments concerns the indoor air quality. The exposure of artwork and materials to gaseous and particulate pollutants introduced by visitors and either indoor or outdoor sources contributes to their decay. In this work, we evaluated the possible monitoring of the visitors' influence using the stable carbon isotopic ratio of CO2 and the concentration of NH3 as a real-time tool. The study was done in the Refectory of Santa Maria delle Grazie (Milan, Italy) which houses one of the most important paintings of Leonardo da Vinci, the Last Supper, and had more than 400,000 visitors in 2019. The results confirmed a good correlation between the presence of tourists inside the museum and the variation of δ13C value during the visits and the closure of the museum. The variation of indoor atmospheric δ13C was influenced by the presence of visitors in the Refectory and delineates the way done from the entrance to the exit. In the same way, the concentration of NH3 was influenced by the presence of visitors and confirmed the role of this one on preservation methodology for indoor air quality in the museum. This new methodology can be used as a supplemental and non-invasive tool to help in calibrating microclimatic conditions through the ventilation rate and air filtration systems in the museum and to manage the number of visitors per turn.

New analytical approach to monitoring air quality in historical monuments through the isotopic ratio of CO2.

In this study, we evaluated indoor air quality to highlight the effects of environmental pollution in the field of cultural heritage. In particular, two important archeological places in the old part of the city of Salerno, Italy, were analyzed: Fruscione Palace and S. Pietro a Corte. The work focused on the influence of tourists on environmental pollution correlated to indoor air quality during some social and cultural events. Moreover, we focused on the possible use of the carbon isotopic composition of CO2 as a tool for environmental studies in the field of cultural heritage. The results showed a good relationship between the isotopic composition of CO2 and the variation of pollutants concentration in the air, demonstrating that it is a valid tool and non-invasive marker to monitor environmental pollution of museums and cultural heritage sites.

Effect of the Polarity of Solvents on Periodic Precipitation: Formation of Hierarchical Revert Liesegang Patterns.

Liesegang pattern (LP) is one example of self-organized periodic precipitation patterns in nonequilibrium systems. Several studies have demonstrated that the LP morphology can track physicochemical environmental conditions (e.g., temperature); however, the polarity effect has not been explored to date. In this study, a copper chromate system is used to reveal the impact of solvent polarity on the evolving LP structure using water/organic solvent mixtures. In the typical case of using water/dimethyl sulfoxide (DMSO) mixtures, two drastic changes in LP morphology with increasing DMSO contents were found: (i) increasing frequency of the original structure and (ii) formation of a hierarchical pattern with the appearance of another, lower-frequency structure. Furthermore, the simulation model operating with a bimodal size distribution, allowing both homogeneous and heterogeneous precipitations showed good agreement with the experimental results. Therefore, this study demonstrated that LP can be tailored by solvent polarity and can be used for designing hierarchical precipitation patterns in a straightforward manner.

Effect of the aqueous matrix on the inactivation of E. coli by permaleic acid.

In this work permaleic acid (PMA) was investigated as possible disinfecting agent and compared to peracetic acid (PAA) in real tap water and wastewater. Preliminary tests in lysogeny broth (LB) were also performed. PMA was synthesized from maleic anhydride and hydrogen peroxide and, for the first time, its antimicrobial activity was evaluated with respect to the growth inhibition of E. coli. The effect of the pH and bivalent ions, typically occurring in real water matrices (namely, Mg2+ and Ca2+), was also investigated. pKa values for PMA were calculated for the first time by DFT calculations. The concentration of bivalent ions strongly affected disinfection efficiency with PMA (Ca2+=0.33 mgL-1 and Mg2+=0.35 mgL-1: 100% E. coli reduction > log 5; Ca2+=13.3 mg L-1 and Mg2+=25.6 mg L-1: E. coli reduction < log 1, after 60 min), and such results were supported by DFT modelling outcomes (pKa2 of PMA 7.3) and disinfection tests in presence of EDTA chelating agent. More alkaline pH conditions drastically decreased PMA disinfection (pH = 5: > log 5 E.coli reduction; pH = 9: < log 1 E.coli reduction, after 60 min). PMA disinfection efficiency is strongly affected by the target water quality, the concentration of metal bivalent ions and the initial pH.

Characterization and authentication of commercial cleaning products formulated with biobased surfactants by stable carbon isotope ratio.

This study focuses on the application of stable carbon isotope analysis to determine the origin of commercial surfactants and cleaning products, especially used in quality process by chemical companies. The δ13C value was applied to commercial surfactants, such as ethoxylate alcohol, sodium lauryl sulfate, alkyl polyglucoside with different origin, that are the most common raw materials used in cleaning products. In this study, the isotopic analysis was performed on mixtures of commercial surfactants to simulate the commercial detergent formulations (handwashing, multisurface cleaner and degreaser) and then on bulk professional cleaning products to match relationship between isotope carbon composition and concentration of surfactants in real samples. This study demonstrated that δ13C was correlated to the origin of surfactants. In particular we analyzed five samples of biobased surfactants, with δ13C value from -22,6‰ to -28,0‰, and six samples from carbon fossil raw material, with δ13C value from -28,5‰ to -32,0‰, which were the most common raw material used in commercial cleaning products. Isotope carbon composition was also applied on mixtures of biobased and fossil surfactants to simulate and perform the method for stable carbon isotope analysis of commercial cleaning products. Furthemore the results assessed the relationship between stable carbon isotope ratio values and surfactant concentration in mixtures: for example in 50% mixtures of biobased (δ13C -22,6‰) and synthetic surfactant (δ13C -32,5‰), we found a δ13C value -28,00‰. The main advantage in using δ13C analysis is related to cheapness and easy-to-operate method in comparison to radiocarbon methodology.

Combination of flow cytometry and molecular analysis to monitor the effect of UVC/H2O2 vs UVC/H2O2/Cu-IDS processes on pathogens and antibiotic resistant genes in secondary wastewater effluents.

The efficiency of a new Advanced Oxidation Process (AOP), namely the photo Fenton like process UV-C/H2O2/IDS-Cu, in removing determinants of antibiotic resistance and pathogenic bacteria was compared to a consolidated AOP (namely UV-C/H2O2) in a secondary treated municipal WasteWater (WW). A reductionist experimental laboratory-based approach was applied on real WW and the parameters were collected by an alternative integrated approach using (i) flow cytometry to enumerate bacteria and test for the fitness of the bacterial communities and (ii) molecular analyses to define the community composition (16S rRNA amplicon sequencing) and the abundances of Antibiotic Resistance Genes (ARGs) and of the class 1 integron (intI1 gene) (by quantitative PCR). The same approach was applied also to post-treatment regrowth tests (24 h) to define the potential persistence of the tested parameters. These experiments were performed in both, human pathogens favorable conditions (HPC, in rich medium and 37°C) and in environmental mimicking conditions (EMC, original WW and 20°C). UV-C/H2O2/IDS-Cu process resulted to be more effective than the UV-C/H2O2in inactivating bacterial cells in the EMC post-treatment regrowth experiments. Both AOPs were efficiently abating potential human pathogenic bacteria and ARGs in the HPC regrowth experiments, although this trend could not be detected in the measurements taken immediately after the disinfection. In comparison with the UV-C/H2O2, the UV-C/H2O2/IDS-Cu process did not apparently offer significant improvements in the abatement of the tested parameters in the WW effluent but, by evaluating the results of the regrowth experiments it was possible to extrapolate more complex trends, suggesting contrasting efficiencies visible only after a few hours. This study offers a detailed view on the abatement efficiency of microbiological/genetic parameters for the UV-C/H2O2/IDS-Cu process, calling for technical adjustments for this very promising technology. At the same time, our results clearly demonstrated the inadequacy of currently applied methodologies in the evaluation of specific parameters (e.g. determinants of antibiotic resistance and pathogenic bacteria) in WW.

Regioselective Ring-Opening of Glycidol to Monoalkyl Glyceryl Ethers Promoted by an [OSSO]-FeIII Triflate Complex.

A FeIII -triflate complex, bearing a bis-thioether-di-phenolate [OSSO]-type ligand, was discovered to promote the ring-opening of glycidol with alcohols under mild reaction conditions (0.05 mol % catalyst and 80 °C). The reaction proceeded with high activity (initial turnover frequency of 1680 h-1 for EtOH) and selectivity (>95 %) toward the formation of twelve monoalkyl glyceryl ethers (MAGEs) in a regioselective fashion (84-96 % yield of the non-symmetric regioisomer). This synthetic approach allows the conversion of a glycerol-derived platform molecule (i.e., glycidol) to high-value-added products by using an Earth-crust abundant metal-based catalyst.

Influence of the synthesis method on the catalytic activity of mayenite for the oxidation of gas-phase trichloroethylene.

Catalytic oxidation of trichloroethylene (TCE) in heterogeneous phase (gas-solid) is an effective strategy for the conversion of this pollutant in less harmful compounds, namely CO2, CO and HCl. In this work, we have studied the use of mayenite, a cost-effective material, as an active catalyst for the TCE conversion. In particular, we have assessed the influence of the mayenite synthesis method (hydrothermal, sol-gel and ceramic) on the reaction performance. The materials have been characterized by different techniques, such as XRD, N2-sorption (BET), TPR, Raman spectroscopy, FESEM-EDX and TEM. The analysis of the light-off curves and product distribution, has shown that the use of the hydrothermal method for the mayenite synthesis results in the most active and selective catalyst. This has been related with a higher surface area and with a higher concentration of oxygen anions in the mayenite prepared by this method. It has been found that the presence of water in the stream do not influence the catalytic performance of the material. A mechanism for the reaction and for the partial deactivation of the catalyst has been proposed.

A new strategy to control the proliferation of microorganisms in solid hospital waste and the diffusion of nosocomial infections.

A possible tool to reduce nosocomial infections is to identify unknown sources of contamination and then to provide a measure for controlling the related infections. In this study, solid hospital waste was considered a potential source of contamination, and a strategy to reduce the potential risk of pathogen contamination was tested. This paper describes a novel technique for waste management in healthcare settings with a view to facilitating infection prevention and control. We explored the innovative use of sodium dichloroisocyanurate (NaDCC) by investigating the microbicidal activity of chlorine, which derives from the hydrolysis of NaDCC mediated by humidity, and by testing its effect on the inhibition of microorganism growth. NaDCC was inserted in a solid hospital waste bin containing also Lauria-Bertani agar plates, with different dilutions of a known titre of three different microorganisms, namely Escherichia coli, Staphylococcus aureus and Aspergillus brasiliensis. The plates were incubated in the container with or without the antimicrobial agent (control, CNT) at room temperature for 5 days. The number of colony-forming units (CFUs) present on each plate was then counted. Microorganisms capable of proliferating in the CNT waste bin were not able to grow in the presence of NaDCC. Furthermore, the molecular chlorine which developed and was released in the waste bin under the experimental conditions (T=20°C, t=5 days) was quantified using iodometric titration. NaDCC hydrolysis, mediated by humidity, has a strong and long-lasting microbicide effect. The proliferation of tested bacteria and fungi is totally inhibited. These results demonstrate the effectiveness of NaDCC in controlling and/or inhibiting microbial proliferation and support its possible use in the treatment of hospital waste to control the spread of nosocomial contamination.

Development of a new radial passive sampling device for atmospheric NOx determination.

In this paper we used Na2CO3-impregnated silica as reactive substrate for the determination of atmospheric NOx (NO+NO2) by using a passive sampling device, with radial symmetry, which is unprecedented. We conducted laboratory and field tests at an urban setting, with co-located passive samplers and continuous measurements of NOx by a chemiluminescence detector, used as reference. The performance of the carbonate-based sorbent for the NOx sampler was evaluated in two different time frames (autumn 2016 and winter 2017), characterised by different environmental conditions. The comparison of the NOx concentration levels measured by passive sampling, using Na2CO3 as NOx sorbent, showed a close relationship with those obtained by the chemiluminescence analyzer. Validation experiments in the laboratory and in the field are reported together with the calculation of the diffusion-sampling rate of the samplers.