322,963 research outputs found
Plastic waste monitoring and recycling by hyperspectral imaging technology
No full textEnvironmentally sound management of plastic waste is a fundamental achievement in order to move towards circular economy and sustainable patterns of consumption and production. In this work, different emerging applications for plastic waste monitoring and recycling based on hyperspectral imaging (HSI) technology, coupled with chemometric logics, are presented and discussed. Marine microplastics, one of the main environmental concerns, can be recognized and characterized by HSI, providing at the same time information related to the particle morphological and morphometrical attributes. Furthermore, some critical issues in plastic recycling can be solved by HSI, as separation of polyolefins, identification of black polymers and recognition of biopolymers in conventional plastic recycled streams
Archaeometric study on orichalcum coins
No full textmetalli, puri o in lega, hanno sempre giocato un ruolo fondamentale nella storia dell’uomo: la produzione regolare di oggetti in rame, ferro, bronzo e oricalco in antichità è infatti attestata dai numerosi ritrovamenti archeologici. In particolare, l’oricalco è una lega a base di rame e zinco, simile al moderno ottone, considerata dagli antichi un’invenzione degli dei. L’antica tecnica utilizzata per la produzione dell’oricalco era la cementazione, diffusa sia in Oriente che tra i popoli del bacino mediterraneo. Usato sin dal primo millennio a.C. in Asia Minore, l’oricalco fu introdotto come lega per la monetazione nel secondo secolo a.C. in Anatolia e solo successivamente nella penisola italica. Qui, Giulio Cesare per primo produsse monete in oricalco, come emissione sperimentale. Ottaviano Augusto, nel 23 a.C., promulgò una riforma monetaria in cui introdusse l’emissione di due nominali in oricalco. Successivamente, con la riforma monetaria di Nerone nel 63-64 d.C. furono introdotti altri tre nominali in oricalco.
La tesi di dottorato di seguito presentata ha lo scopo di caratterizzare la lega di oricalco e valutarne il degrado, attraverso uno studio archeometrico di monete antiche emesse tra il primo secolo a.C. e la fine del primo secolo d.C. Allo scopo, sono state impiegate tecniche non distruttive, nano-invasive e distruttive. In particolare, metodologie superficiali (XRF, FTIR-ATR, VIMP) hanno permesso una prima caratterizzazione delle monete in oricalco e degli strati superficiali della patina. Con tecniche di microscopia (SEM-EDS, FIB-FESEM-EDS, HR-FESEM-EDS) è stato possibile studiare le microstrutture tipiche della lega oricalco, il pattern corrosivo delle patine e il loro sviluppo all’interno dei campioni. L’analisi quantitativa (attraverso l’EMPA) dei nuclei non corrosi e delle patine dei campioni ha consentito la caratterizzazione dell’oricalco e la descrizione del processo di dezincificazione. Attraverso l’approccio multianalitico è stato possibile identificare caratteri di autenticità dei campioni, differenziare le monete per emissione e riesaminare le precedenti teorie utilizzate per la datazione di campioni in oricalco.
Per tanto, con questa tesi di dottorato si è voluto contribuire alle attuali conoscenze sulla coniazione romana in oricalco e si è tentato di approfondire i meccanismi dei processi corrosivi a carico delle leghe antiche.Metals, pure or in alloy, have always played a fundamental role in human history. Indeed, the regular roduction in antiquity of objects in copper, iron, bronze and orichalcum is attested by the numerous archaeological findings. In particular, the orichalcum is a copper-zinc based alloy, similar to the modern brass, considered by the ancient populations an invention of the gods. The cementation was the ancient technique used for the production of the orichalcum, common both in the East and in the Mediterranean basin. Used since the first millennium BC in Asia Minor, the orichalcum was introduced as alloy for coinage in Anatolia in the second century BC and only later was adopted in the Italian peninsula. Here, Julius Caesar first produced coins in orichalcum, as an experimental emission. Octavianus Augustus, in the 23 BC, promulgated a monetary reform, introducing two denominations in orichalcum. Subsequently, with the monetary reform of Nero in 63-64 AD three other denominations in orichalcum were introduced.
The PhD thesis presented below aims to characterise the orichalcum alloy and to evaluate its degradation, through an archaeometric study of ancient coins issued between the first century BC and the end of the first century AD. For this purpose, non-destructive, nano-invasive and destructive techniques were used. In particular, surface methodologies (XRF, FTIR-ATR, VIMP) allowed a first characterization of the orichalcum coins and the superficial investigation of the patinas. With microscopy techniques (SEM-EDS, FIBFESEM-EDS, HR-FESEM-EDS) it was possible to study the typical microstructures of the orichalcum alloy, the corrosive pattern of the patinas and their development within the samples. The quantitative analysis (through the EMPA) of non-corroded cores and patinas of the samples allowed the characterization of the ancient orichalcum and the description of the dezincification process. Therefore, using a multi-analytical approach it was possible to define the authenticity of the samples, to grouping the coins by emission and to review the previous theories used for dating samples in orichalcum.
This PhD thesis wanted to contribute to the current knowledge on Roman coinage in orichalcum and to attempt investigating the mechanisms of corrosive processes affecting ancient alloys
Recycling Technologies
No full textRecycling Technologies: Paper Fiber
Waste Paper Characteristics
Waste Paper Recycling Technologies
Recycling Technologies: Glass
Cullet Contaminants
Cullet Recycling Technologies
Recycling Technologies: Metals
Ferrous Metals
Ferrous Metal Recycling Technologies
Nonferrous Metals
Nonferrous Metal Recycling Technologies
Recycling Technologies: Plastics
Waste Plastic Sources and Characteristics
Waste Plastic Recycling Technologies
Recycling Technologies: Fibers (Textiles and Carpets)
Textiles
Textiles Recycling Technologies
Carpets
Carpet Recycling Technologies
Future Directions: Innovative Control/Sorting
Devices/Logics Integration in Recycling Plant
Hyperspectral imaging and hierarchical PLS-DA applied to asbestos recognition in construction and demolition waste
No full textAsbestos-Containing Materials (ACMs) are hazardous and prohibited to be sold or used as recycled materials. In the past, asbestos was widely used, together with cement, to produce "asbestos cement-based" products. During the recycling process of Construction and Demolition waste (C&DW), ACM must be collected and deposited separately from other wastes. One of the main aims of the recycling strategies applied to C&DW was thus to identify and separate ACM from C&DW (e.g., concrete and brick). However, to obtain a correct recovery of C&DW materials, control methodologies are necessary to evaluate the quality and the presence of harmful materials, such as ACM. HyperSpectral Imaging (HSI)-based sensing devices allow performing the full detection of materials constituting demolition waste. ACMs are, in fact, characterized by a spectral response that nakes them is dierent from the "simple" matrix of the material/s not embedding asbestos. The described HSI quality control approach is based on the utilization of a platform working in the short-wave infrared range (1000-2500 nm). The acquired hyperspectral images were analyzed by applying different chemometric methods: Principal Component Analysis for data exploration and hierarchical Partial Least-Square-Discriminant Analysis (PLS-DA) to build classification models. Following this approach, it was possible to set up a repeatable, reliable and efficient technique able to detect ACM presence inside a C&DW flow stream. Results showed that it is possible to discriminate and identify ACM inside C&DW. The recognition is potentially automatic, non-destructive and does not need any contact with the investigated products
Techniques for separation of plastic wastes
No full textGlobal plastic production is continuously increasing and there is a strong need to increase plastic recycling accordingly. The most demanded polymers and their main applications are introduced and an overview of the different operations forming the plastic recycling chain is presented. Mechanical recycling is the most important option to recover plastics; it can be carried out at “macro” or “micro” level, depending on the size of plastic waste. Separation technologies are divided into gravity separation, electrostatic separation, magnetic density separation, flotation, and sensor-based sorting. Auxiliary technologies usually found in plastic recycling plants are also described: magnetic and Eddy current separators. The importance of recycled plastic quality control and product certification is strongly pointed out, reporting both traditional and advanced quality measurement techniques. The final section is devoted to list some of the main current research topics on plastic recycling
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