An Overview of the Sorption Studies of Contaminants on Poly(Ethylene Terephthalate) Microplastics in the Marine Environment

Marine pollution is one of the biggest environmental problems, mainly due to single-use or disposable plastic waste fragmenting into microplastics (MPs) and nanoplastics (NPs) and entering oceans from the coasts together with human-made MPs. A rapidly growing worry concerning environmental and human safety has stimulated research interest in the potential risks induced by the chemicals associated with MPs/NPs. In this framework, the present review analyzes the recent advances in adsorption and desorption studies of different contaminants species, both organic and metallic, on MPs made of poly (ethylene terephthalate). The choice of PET is motivated by its great diffusion among plastic items and, unfortunately, also in marine plastic pollution. Due to the ubiquitous presence of PET MPS/NPs, the interest in its role as a vector of contaminants has abruptly increased in the last three years, as demonstrated by the very high number of recent papers on sorption studies in different environments. The present review relies on a chemical engineering approach aimed at providing a deeper overview of both the sorption mechanisms of organic and metal contaminants to PET MPs/NPs and the most used adsorption kinetic models to predict the mass transfer process from the liquid phase to the solid adsorben

Transport Properties of Natural and Artificial Smart Fabrics Impregnated by Graphite Nanomaterial Stacks

none4noIn this work, we studied the transport properties (thermal and electrical conductivity) of smart fabric materials treated with graphite nanomaterial stacks–acetone suspensions. An innovative and easy method to produce graphite nanomaterial stacks–acetone-based formulations, starting from a low-cost expandable graphite, is proposed. An original, economical, fast, and easy method to increase the thermal and electrical conductivity of textile materials was also employed for the first time. The proposed method allows the impregnation of smart fabric materials, avoiding precoating of the fibers, thus reducing costs and processing time, while obtaining a great increase in the transport properties. Two kinds of textiles, cotton and Lycra®, were selected as they represent the most used natural and artificial fabrics, respectively. The impact of the dimensions of the produced graphite nanomaterial stacks–acetone-based suspensions on both the uniformity of the treatment and the transport properties of the selected textile materials was accurately evaluated using several experimental techniques. An empirical relationship between the two transport properties was also successfully identified. Finally, several theoretical models were applied to predict the transport properties of the developed smart fabric materials, evidencing a good agreement with the experimental data.openCarola Esposito Corcione; Francesca Ferrari; Raffaella Striani; Antonio GrecoESPOSITO CORCIONE, Carola; Ferrari, Francesca; Striani, Raffaella; Greco, ANTONIO STEFAN

Coating's influence on wind erosion of porous stones used in the Cultural Heritage of Southern Italy: Surface characterisation and resistance

Wind erosion (or aeolian corrosion) is one of the most relevant causes of weathering and degradation which has affected building surfaces in Cultural Heritage. The effect depends on the wind strength, the impact of particles transported and their size and the characteristics of surfaces affected. This aspect is very important for historical buildings constructed by using limestone as Lecce stone (LS). LS has an extraordinary ability to be shaped, but is very sensitive to decay. Exfoliation, wind erosion, absorption of water by capillary from the soil, are its main degradation causes. For such a reason, the application of effective products able to act as “sacrifice film” became necessary in order to minimise the degradation rate by preserving the limestone substrate against serious weathering agents. In this work, the effects of aeolian corrosion, simulated by means the accelerated test with sandblasting method, were studied. In particular, the effectiveness of two specific commercial coatings, such as an innovative free-solvent hybrid organic-inorganic coating (HYBRID) and a solvent-based coating (AS), was assessed relating to their capability to preserve Lecce stone from the aeolian corrosion phenomenon. The protective efficacy was guaranteed by both the commercial coatings even after accelerated wind erosion test, by confirming a high hydrophobicity, low capillary water absorption and an adequate depth of penetration inside the stone able to assure durability

Sustainable Polymer Composites Manufacturing through 3D Printing Technologies by Using Recycled Polymer and Filler

In the last years, the excessive use of plastic and other synthetic materials, that are generally difficult to dispose of, has caused growing ecological worries. These are contributing to redirecting the world's attention to sustainable materials and a circular economy (CE) approach using recycling routes. In this work, bio-filaments for the Fused Filament Fabrication (FFF) 3D printing technique were produced from recycled polylactic acid (PLA) and artisanal ceramic waste by an extrusion process and fully characterized from a physical, thermal, and mechanical point of view. The data showed different morphological, thermal, rheological, and mechanical properties of the two produced filaments. Furthermore, the 3D objects produced from the 100% recycled PLA filament showed lower mechanical performance. However, the results have demonstrated that all the produced filaments can be used in a low-cost FFF commercial printer that has been modified with simple hand-made operations in order to produce 3D-printed models. The main objective of this work is to propose an example of easy and low-cost application of 3D printing that involves operations such as the reprocessing and the recyclability of materials, that are also not perfectly mechanically performing but can still provide environmental and economic benefits

The Role of 3D Printing in the Development of a Catalytic System for the Heterogeneous Fenton Process

Recycling of catalysts is often performed. Additive manufacturing (AM) received increasing attention in recent years in various fields such as engineering and medicine, among others. More recently, the fabrication of three-dimensional objects used as scaffolds in heterogeneous catalysis has shown innumerable advantages, such as easier handling and waste reduction, both leading to a reduction in times and costs. In this work, the fabrication and use of 3D-printed recyclable polylactic acid (PLA) scaffolds coated with an iron oxide active catalyst for Fenton reactions applied to aromatic model molecules, is presented. These molecules are representative of a wider class of intractable organic compounds, often present in industrial wastewater. The 3D-printed PLA-coated scaffolds were also tested using an industrial wastewater, determining the chemical oxygen demand (COD). The catalyst is characterized using electron microscopy coupled to elemental analysis (SEM/EDX) and thermogravimetry, demonstrating that coating leach is very limited, and it can be easily recovered and reused many times

An Innovative Method for the Recycling of Waste Carbohydrate Based Flours

This work represents an innovative study that, for the first time, explores the possibility to use waste flours to produce thermoplastic polymeric bio-films. To the best of our knowledge, this is the first time that waste flours, derived from bakeries, pizzerias or pasta factories, have been proposed for the production of bio-polymers, as a replacement of neat starch. To this aim, durum waste flour derived from a pasta factory, soft waste flour derived from pizzerias and neat maize starch used as control material were firstly analyzed from dimensional, morphological and chemical points of view. Afterwards, waste flour films were produced by the addition of a nature-based plasticizer, glycerol. Mechanical characterization of the plasticized thermoplastic films, produced by compression molding, evidenced low performances, even in the case of the neat maize starch. In order to improve the mechanical properties, the possibility to include polylactic acid and cardanol based plasticizer was also investigated. Mass transport properties of all the produced bio-films were investigated by measuring their water vapor permeability and hygroscopic absorption. The durability properties of the bio-films were assessed by accelerated ageing tests, while the biodegradability of the waste-based films was evaluated by measuring the solubility and the degradation in water. The physicochemical analyses of the novel bio-films evidenced good mechanical properties; specifically, the waste-based films showed a lower hygroscopic absorption and water solubility than those of the blends containing neat starch

valorization of food industries wastes for the production of poly vinyl alcohol pva biodegradable composites

This work is aimed to the development of new green composite materials by the incorporation of natural additives into poly(vinyl) alcohol (PVA). Two additives, shredded walnut shells and organic fraction of municipal solid waste (MW), were used to improve the mechanical properties of PVA. Both additives, derived from food industry wastes, were added in a PVA/water solution, which allowed to produce samples by the use of a pressure free process. Rheological analysis was performed in order to study the evolution of the material viscosity during thermal treatment, aimed at water removal. Samples obtained were characterized by means of differential scanning calorimetry (DSC), showing an improvement of the glass transition temperature brought by the addition of walnut shells. Finally, flexural tests were carried out on samples obtained after the incorporation of the different additives in PVA and compared with the mechanical properties of the neat matrix. Results obtained indicate the potential improvement brought by the addition of walnut shells, which allows increasing the flexural modulus of about 50%, at the expenses of a flexural strength reduction of about 30%. Also, at least for low amount of added water, the addition of MW was shown to provide an increase of the strain at break equal to 100%

Shaping ability of ProTaper Ultimate and BlueShaper in mandibular molars: a micro-CT evaluation

Aim: The study aimed to evaluate the shaping characteristics of ProTaper Ultimate (Dentsply Sirona) and BlueShaper (Zarc4Endo) using microcomputed tomographic imaging technology (micro-CT). Methods: Thirty mesial and distal canals of extracted second mandibular molars with similar anatomy were selected and scanned pre- and postoperatively by micro-CT scanning (SkyScan 1172, Bruker micro-CT) with a voxel size of 11 mu m and shaped with two different procedures: ProTaper Ultimate (Group 1: n = 15) and BlueShaper (Group 2: n = 15) were used following the manufacturer's recommendations up to final 30 apical size. Irrigation was ensured in all groups with 5.25% NaOCl and 10% EDTA during instrumentation. Canal transportation, the volume of removed dentin, and area of untreated surface were matched with preoperative values with Bruker CT Analyser (Bruker micro-CT). Data were statistically analyzed using Student's t-test. Results: No significant differences were observed between Group 1 and Group 2 in terms of canal transportation, volume of removed dentin, and untreated surfaces. A significant difference (p < 0.05) in the amount of untreated surfaces was found between the mesial and distal canals in both groups. Conclusion: Shaping procedures with both ProTaper Ultimate and BlueShaper demonstrated similar canal enlargement volumes and similar canal transportation without evidence of significant preparation errors. Nevertheless, a high amount of untreated surface was reported for both systems, particularly in distal canals

Autofluorescence of Model Polyethylene Terephthalate Nanoplastics for Cell Interaction Studies

This work contributes to fill one of the gaps regarding nanoplastic interactions with biological systems by producing polyethylene terephthalate (PET) model nanoplastics, similar to those found in the marine environment, by means of a fast top-down approach based on mechanical fragmentation. Their size distribution and morphology were characterized by laser diffraction and atomic force microscopy (AFM). Their autofluorescence was studied by spectrofluorimetry and fluorescence imaging, being a key property for the evaluation of their interaction with biota. The emission spectra of label-free nanoplastics were comparable with those of PET nanoplastics labeled with Nile red. Finally, the suitability of label-free nanoplastics for biological studies was assessed by in vitro exposure with Mytilus galloprovincialis hemolymphatic cells in a time interval up to 6 h. The nanoplastic internalization into these cells, known to be provided with phagocytic activity, was assessed by fluorescence microscopy. The obtained results underlined that the autofluorescence of the model PET nanoplastics produced in the laboratory was adequate for biological studies having the potential to overcome the disadvantages commonly associated with several fluorescent dyes, such as the tendency to also stain other organic materials different from plastics, to form aggregates due to intermolecular interactions at high concentrations with a consequent decrease in fluorescence intensity, and to dye desorption from nanoparticles. The results of the autofluorescence study provide an innovative approach for plastic risk assessment

Incorporation of functional polymers into metal halide perovskite thin-films: from interactions in solution to crystallization

In the last decade, metal halide perovskite materials (MHPs) have presented several innovative opportunities for optoelectronic technologies, particularly for solar cells. However, challenges related to reliable material processability, combined with inherent instability, pose major roadblocks in the path towards the industrialization of MHP-based technologies. One of the strategies, developed to overcome these issues, is the incorporation of polymeric additives to control the crystallization process of the material, which represents a key aspect for reproducible manufacturing of robust films. Owing to the vast range of properties presented by polymeric materials, a judicious selection of polymers and perovskite compositions allows tailoring the physical-chemical-mechanical properties of the final composite to the desired device application. In this review, the recent advances on polymer inclusion into perovskite photoactive layers for solar cells are discussed. Following a brief introduction to perovskite fundamental properties for photovoltaic applications, the focus is on the self-assembly process of MHPs and on the use of polymers with different functionalities as templating agents for the growth of polycrystalline films with optimal optoelectronic quality. The influence of different polymers on the stability, mechanical behavior and processability of MHPs is then rationalized. Finally, a summary of the most significant and accessible characterization techniques used to investigate the polymer-perovskite-based composite is given, providing guidelines for the further development of innovative formulations.Incorporation of polymers represents a viable new strategy to solve the major challenges related to metal halide perovskite materials in view of future commercialization