Key Engineering Materials Vol. 885

Abstract: This study proposes an innovative coating material and procedure to extend the shelf-life of fresh-cut pineapple classified as “minimally processed foods”. The novelty of this work consists of the using of biodegradable cases for the storage of fruits during the experiments under refrigerated conditions. In addition, the application of the coating process was evaluated over a period of 15 days and a complete characterization of the Volatile Organic Compounds (VOCs) was performed by gaschromatography coupled to mass spectrometry (GC-MS) to assess the effect of the coating material on the flavor, the appearance and the quality of the fruits. Results demonstrated that the application of carboxymethyl cellulose and ascorbic acid on pretreated fresh-cut pineapple is able to reduce the aging process and prolonge the shelf-life of pineapple without requiring conventional PVC cases for storage.

Abstract: The removal of mercury from the waterbody remains a severe challenge in ensuring environmental safety due to its highly toxic and non-biodegradable properties. Adsorption is an evidently effective method for heavy metal removal in water. This research aims to study the mercury (II) ion adsorption behavior in aqueous solution onto extruded natural bentonite in monolithic structure, bentonite-based monolith (BBM) adsorbent. BBM was characterized by XRD, BET, and SEM, the results verify BBM could improve adsorption performance assumed on its structure. Adsorption efficiency, isotherm model, and adsorption kinetic were investigated. Experiments were performed in a lab-scale batch reactor with mercury solution concentration varied from 1 to 5 mg/L. The maximum adsorption efficiency discovered to be 63,9%. The experimental data fitted well to Langmuir isotherm (non-linear) and kinetic model pseudo first order (non-linear), revealing the maximum monolayer capacity (Q_o) of BBM to be 0,187 mg/g with Langmuir constants K_L and a_L are 0,215 L/g dan 1,151 L/mg respectively. These value confirms that BBM adsorbent encompasses tremendous potential for mercury (II) ion removal in a solution.

Abstract: The economic’s development also bring urbanization and industrialization in many countries. However, many pollutants are also discharged into the environment, especially heavy metals (Zinc) seriously affects people's life and health as well as the water environment. This study reports on the preparation of activated carbon materials modified with HNO₃ from Cassia Fistula seed for heavy metal removal. The results showed that zinc removal efficiencies were 65.06%; 72.19%; 75.64%; 78.57% corresponds to concentrations of 50, 30, 20, 10 ppm at optimal survey conditions pH 5, dosage of 0.3 g/50ml and 60 minutes processing time. The research results show that the activated carbon modified with HNO₃ from Cassia Fistula seed is a promising absorption material for heavy metal removal in wastewater.

Abstract: The paper presents results of the composite polymer-containing layers formation by plasma electrolytic oxidation (PEO) with subsequent application of the superdispersed polytetrafluoroethylene (SPTFE) aqueous suspension. The corrosion properties and adhesion of coatings have been investigated using potentiodynamic polarization and scratch tests. Incorporation of SPTFE decreased the corrosion current density for composite layers by more than 3 orders of magnitude in comparison with the base PEO-coating and increased the coatings adhesion by 30 %.

Abstract: In this paper, results of feasibility study on microplastics (MPs) assessment in leachates from the Latvian solid municipal landfill Getliņi are discussed. The application of leachates for the treatment of cigarette butts (CGB) was evaluated. Methods of fluorescent microscopy, Fourier transform infrared (FTIR) spectroscopy and FTIR-microscopy were used for the identification and characterization of MPs in the leachates and analysis of CGB. Presence of the secondary MPs (e.g., degraded polyolefin mixtures) was determined in the tested landfill leachates, while cellulose acetate (CA) was not determined in these products. The leachates were tested as potential media for the thermophilic (55°C) fermentation of CGB without air supply. Degradation of CGB was determined after one-week fermentation that was confirmed comparing the changes in FTIR spectra of CA prior and after the treatment. This study provoked a path for further experimental studies of controlled degradation of cigarette butts under natural conditions in landfill environments.

Abstract: The management of post-consumer plastic waste (PCPW) is a real challenging issue due to difficulties in effectively identifying and sorting the collected plastics and in their mechanical recycling. Indeed, mechanically recycled post-consumer plastic waste usually shows poor performances compared to virgin materials, due to incompatibility between constituents, presence of degraded materials, hygroscopicity and bad odors. Compatibilizers and nanoparticles can help to improve recycled plastics quality, but to be chosen and dosed properly they require an in-depth knowledge and characterization of the raw waste. In this study, an analysis of polymeric materials obtained from the separation and mechanical recycling of post-consumer plastic wastes from urban collection as pellets (UPW) is reported. In particular, the experimental characterization was carried out in order to identify UPW composition, water content, physical-chemical properties and processability. It was found that UPW samples are mainly constituted of polyethylene (PE) and polypropylene (PP) in equal parts. UPW was submitted to a melt processing operation, using a lab-scale single-screw extruder, obtaining ribbons that were completely characterized. With the aim to investigate the effect of water content on the recycled material processability and performance, the recycling process was carried out both on undried and dried UPW pellets.

Abstract: In this work, blown films made by blends of poly (lactide) (PLA) and poly (butylene-adipate-co-terephthalate) (PBAT) in a 40/60 mass ratio were developed and characterized. Two types of PLA, differing for their viscosities, were employed, in order to evaluate their effect on the morphology and on the mechanical properties of the films. The blends exhibited a coarse morphology when the viscosity of the PLA employed was much higher than PBAT. Instead, the use of a PLA whose viscosity was closer to PBAT led to a decrease of the dimensions and to a better distribution and interfacial adhesion of the dispersed phase. Moreover, the finer and more homogenous morphology of the blend resulted in better mechanical performance of the system.

Abstract: Zinc oxide nanostructures have potentially interesting optical properties, which make them candidates for use in applications within the area of optoelectronics; their synthesis can be carried out through low-cost methods, such as sol gel, among many others. In addition, depending on the synthesis method, its shape and size, ZnO nanostructures can present emissions in the ultraviolet (UV) and visible region. By doping with elements such as carbon, silver, copper or some rare earth, for example, erbium, terbium or neodymium, the optical properties of ZnO can be adjusted and controlled to be able to be applied in the production of biosensors, photodetectors and even sensors of white light. In this research work, a review is presented on the nature of the optical transition mechanisms that occur in the ZnO nanostructures synthesized by the sol-gel method.

Abstract: The current edition of Eurocode 8 does not cover the design of the Cold-Formed steel (CFS) building structures under the seismic design condition. As part of the revision process of Euro-code 8 to reflect the outcomes of extensive research carried out in the past decade, University of Naples “Federico II” is involved in the validation of existing seismic design criteria and development of new rules for the design of CFS systems. In particular, different types of Lateral Force Resisting System (LFRS) are analyzed that can be listed in the second generation of Eurocode 8. The investigated LFRS’s include CFS strap braced walls and CFS shear walls with steel sheets, wood, or gypsum sheathing. This paper provides the background information on the research works and the reference design standards, already being used in some parts of the world, which formed the basis of design criteria for these LFRS systems. The design criteria for the LFRS-s common to CFS buildings would include rules necessary for ensuring the dissipative behavior, appropriate values of the behavior factor, guidelines to predict the design strength, geometrical and mechanical limitations.

Abstract: This paper investigates the performance of extended stiffened end-plate bolted beam-to-column joints subjected a column loss scenario by means of finite element simulations. An advanced numerical model was developed, and its effectiveness was validated against the experimental results. The influence of the bolt strengthening on the column loss action was investigated changing the grade of bolts. The results showed that the joint performance under column loss scenario are deeply related to the development of the catenary action that depends from the connection ductility; therefore increasing the bolt material strength will provide beneficial effects on the joint capacity under the column loss.