Loris Pietrelli

Rare earths recovery from NiMH spent batteries

Nickel-metal hydride batteries (NiMH) contain rare earths (RE) and a variety of valuable metals such as nickel and cobalt. Using a hydrometallurgical process developed for the recovery of metals from spent batteries, a selective separation of RE by precipitation of Sodium RE double sulfate can be performed. Leaching solution was obtained by using 2 M H2SO4 at 20 °C. The paper reports the experimental studies involving the precipitation process and the characterisation by X-ray diffraction of the resulting product (Sodium RE double sulfates). It has been shown that it is possible to recover about 80% of the RE contained in spent NiMH batteries.

Separation of middle rare earths by solvent extraction using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant

Abstract The extraction of the trivalent middle rare earths from chloride media by kerosene solutions of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant was studied. The separation factors between the elements using solution simulating wastes from NiMH spent batteries have been evaluated: the order of the extractive ability of extractant can be confirmed in Tb>Gd>Eu>Sm.

Antimicrobial and antioxidant amphiphilic random copolymers to address medical device-centered infections

Microbial biofilms are known to support a number of human infections, including those related to medical devices. This work is focused on the development of novel dual-function amphiphilic random copolymers to be employed as coatings for medical devices. Particularly, copolymers were obtained by polymerization of an antimicrobial cationic monomer (bearing tertiary amine) and an antioxidant and antimicrobial hydrophobic monomer (containing hydroxytyrosol, HTy). To obtain copolymers with various amphiphilic balance, different molar ratios of the two monomers were used. (1)H NMR and DSC analyses evidenced that HTy aromatic rings are able to interact with each other leading to a supra-macromolecular re-arrangement and decrease the copolymer size in water. All copolymers showed good antioxidant activity and Fe(2+) chelating ability. Cytotoxicity and hemolytic tests evidenced that the amphiphilic balance, cationic charge density and polymer size in solution are key determinants for polymer biocompatibility. As for the antimicrobial properties, the lowest minimal inhibitory concentration (MIC = 40 μg/mL) against Staphylococcus epidermidis was shown by the water-soluble copolymer having the highest HTy molar content (0.3). This copolymer layered onto catheter surfaces was also able to prevent staphylococcal adhesion. This approach permits not only prevention of biofilm infections but also reduction of the risk of emergence of drug-resistant bacteria. Indeed, the combination of two active compounds in the same polymer can provide a synergistic action against biofilms and suppress reactive species oxygen (ROS), known to promote the occurrence of antibiotic resistance.

CESIUM ADSORPTION WITH ZEOLITES FROM NUCLEAR HIGH SALT CONTENT ALKALINE WASTES

ABSTRACT The sorption of cesium with zeolites was investigated from an alkaline nuclear waste containing sodium aluminate and sodium nitrate. Isotherms at different temperatures and for different sodium concentrations have been assessed; kinetics was investigated in batch tests. Break through curves are reported both for laboratory and pilot plant columns. For a high salt content alkaline solution (MCE) a capacity of 1 mg of Cs per gram of zeolite was found in fixed bed column operation at room temperature.

Microplastic pollution in the surface waters of Italian Subalpine Lakes

Plastic debris incidence in marine environment was already highlighted in the early 1970s. Over the last decade, microplastic pollution in the environment has received increasing attention and is now an emerging research area. Many studies have focused on quantifying microplastic abundance in the marine environment, while there are relatively few data on microplastic occurrence in freshwater environment. Recent studies have reported high concentrations of microplastics in lakes and rivers, although the understanding of several factors influencing source, transport and fate is still limited. This study compares different lakes and the common factors, which could influence the occurrence and distribution of microplastics. The three subalpine lakes monitored include Lake Maggiore, Iseo and Garda. The selected sampling transects reflect the hydrologic conditions, the morphometric characteristics of these lakes, and other factors influencing the release of plastics debris in lakes. Particles of microplastics (<5 mm) were found in all sampled surfaces. The particles collected were classified depending on their number, shape and composition. The shape distribution showed the dominating occurrence of fragments (73.7%). The chemical composition of all examined samples clearly shows dominating presence of polyethylene (45%), polystyrene (18%) and polypropylene (15%). The results provide significant relations among the different contribution of direct and diffuse sources to the quantity of microplastics, highlighting the importance of understanding the spatial distribution dynamics of microplastics within a lake system that acts as a sink and source of plastic particles.

Antimicrobial activity of catechol functionalized-chitosan versus Staphylococcus epidermidis

Protein mussel-inspired adhesive polymers, characterized by the presence of catechol groups, possess superior muco-adhesive properties and have great potentiality in wound healing. Suitable materials for wound dressing should properly combine muco-adhesiveness and antimicrobial activity. In this work, catechol-functionalized chitosan was obtained by reaction with hydrocaffeic acid (HCAF), in order to investigate how catechol introduction at different content could affect the intrinsic antimicrobial activity of the polymer itself. Unexpectedly, an enhancement of chitosan antimicrobial activity was observed after catechol functionalization, with a fourfold reduction in the polymer minimum inhibitory concentration versus Staphylococcus epidermidis. Additionally, a commercial wound dressing coated with one of the synthesized CS-HCAF derivatives showed a significant reduction in the adhesion of S. epidermidis compared to the uncoated dressing (3-log reduction). The CS-HCAF derivatives also showed an interesting antioxidant property (EC50 ranging from 20 to 60μg/mL), which further confirms the potentiality of these materials as wound dressings.

Plastisphere in action: evidence for an interaction between expanded polystyrene and dunal plants

Among the many threats that can be recorded on sandy beaches, plastic litter represents a serious problem for these complex and endangered ecosystems. Expanded polystyrene (EPS) is increasingly abundant as a form of plastic litter in natural environments, particularly along shores and waterways. Nevertheless, despite the great number of scientific articles concerning the impact of litter on animal species, there are still no research focusing on the interaction between this type of beach litter and other biodiversity components. In this work, we reported the first evidence of interactions between EPS and living plants along a sandy beach of Tyrrhenian central Italy. We sampled 540 EPS items, mainly deriving from fishery activities (>75%). We obtained evidence for an interaction between EPS and plants: about 5% of items resulted perforated or have roots of three species (Phragmites australis, Spartina versicolor, Anthemis maritima). Apparently, we did not observed a relationship between plants and EPS items size. More research is needed to assess if the plant assemblage growing on EPS is random or if peculiar substrate exerts some sort of selection on the plant community.

Measuring non-biological diversity using commonly used metrics: Strengths, weaknesses and caveats for their application in beach litter management

Due to increasing worldwide anthropogenic pressure and in order to promote adequate environmental conservation strategies, quantification of non-biological diversity, such as considering marine and beach litter, is becoming increasingly useful. Information on beach litter in terms of richness and diversity may have a consistent influence regarding the evaluation of its pressure and impact on coastal ecosystems. Highlighted are strengths, weaknesses and caveats concerning the use of uni- and bi-variate diversity metrics applied to a class of man-made non-biological objects periodically accumulated on the beaches. Two case studies show evidence that the application of diversity metrics on non-biological objects may have different implications. In absence of a universal and standardized non-biological taxonomy, it is important to be cautious when comparing values obtained from non-living assemblages, in particular if different sites, time or operators are considered. Moreover, different indices provide different information. Therefore, users should pay particular attention on the application of diversity metrics, addressing specific research questions and avoiding automatic calculation of redundant and “magic” indices.

Dyes Adsorption from Aqueous Solutions by Chitosan

In this study the ability of chitosan to remove acid, basic, reactive, and direct dyestuffs by adsorption was studied. The effect of several factors influencing dye adsorption such as dye concentration, grain size, pH, and temperature were investigated. Desorption of dyes at different pH was also examined. It was shown that the adsorption capacities of chitosan were comparatively high for acid and direct dyes and that the adsorption was controlled by the acidity of the solution. The kinetics of adsorption were found to be of pseudo second order. Batch isotherm studies showed that adsorption of dyes from aqueous solution by chitosan was described by the Langmuir equation.

An Unexpected Consequence of Plastic Litter Clean-Up on Beaches: Too Much Sand Might Be Removed

We removed plastic meso- and macro-litter (PML) during a beach clean-up practice on a protected Mediterranean sandy beach in central Italy from the high tide line to a berm half-way up the beach and from the berm to a sand dune the rest of the way up the beach. Plastic fragments, cotton buds, and expanded polystyrene (EPS) fragments were the most common categories constituting about 90% of total abundance. We separated sand from PML and found that the weight of the sand was about 14% of the total weight removed. Although our data may be affected by local factors, they have general implications for management actions. Environmental practitioners who develop projects in beach cleaning should pay attention when removing PML since a significant amount of sand could be unintentionally removed resulting in unnecessary material in landfills or other disposal, and over time potentially could significantly affect sandy beaches.