Study of the biodegradation in soil of new generation plastics ?· 1 Study of the biodegradation in…

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  • UNIVERSITA DEGLI STUDI DI MILANO-BICOCCA

    Facolt di Scienze Matematiche, Fisiche e Naturali

    Dottorato in Scienze Ambientali (XXIII)

    Study of the biodegradation in soil of new generation plastics

    Tutor: Dott.ssa Valeria MEZZANOTTE Dottoranda: Michela SIOTTO

    Matricola 549660

    Anno accademico 2008-2010

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    Contents 1 Study of the biodegradation in soil of new generation plastics ..........5

    1.1 Introduction........................................................................................5 1.2 Structure of the research ....................................................................9

    REFERENCES .................................................................................11

    2 Mineralization of monomeric components of biodegradable plastics in soil ............................................................................................................13

    ABSTRACT......................................................................................13 2.1 Introduction......................................................................................14 2.2 Materials and Methods.....................................................................15

    2.2.1 The tested substances ................................................................15 2.2.2 Soil samples ..............................................................................17 2.2.3 Biodegradation tests ..................................................................18 2.2.4 Chemicals and analytical methods ............................................18

    2.3 Results..............................................................................................19 2.4 Discussion and Conclusions ............................................................23

    REFERENCES .................................................................................25

    3 Kinetics of monomer biodegradation in soil ......................................29 ABSTRACT......................................................................................29

    3.1 Introduction......................................................................................30 3.2 Materials and Methods.....................................................................32

    3.2.1 Tested substances ......................................................................32 3.2.2 Biodegradation tests ..................................................................33 3.2.3 Chemicals and analytical methods ............................................35 3.2.4 Modeling and data processing...................................................35

    3.3 Results..............................................................................................38 3.4 Discussion........................................................................................42 3.5 Conclusions......................................................................................43

    APPENDIX.......................................................................................44 REFERENCES .................................................................................45

    4 Influence of compost and starting soil pH on mineralization in soil of a model aliphatic polyester.........................................................................49

    ABSTRACT......................................................................................49 4.1 Introduction......................................................................................50 4.2 Materials and Methods.....................................................................51

    4.2.1 The tested substances ................................................................51 4.2.2 Soil ............................................................................................51 4.2.3 Biodegradation tests ..................................................................51 4.2.4 Analytical methods....................................................................52 4.2.5 Experimental plan .....................................................................52

    4.3 Results..............................................................................................54

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    4.3.1 Tests of the first group ..............................................................54 4.3.2 Test of the second group ...........................................................56

    4.4 Discussion........................................................................................57 4.4.1 The cellulose .............................................................................57 4.4.2 The model polyester ..................................................................59

    4.5 Conclusions......................................................................................60 REFERENCES .................................................................................61

    5 Preliminary results about sensitivity of soil combustion to determine organic matter in soil samples ...................................................................63

    ABSTRACT......................................................................................63 5.1 Introduction......................................................................................64 5.2 Materials and Methods.....................................................................66

    5.2.1 Soil and organic matter sources ................................................66 5.2.2 Volatile solids determination ....................................................66 5.2.3 Experimental set up...................................................................67

    5.3 Results and Discussion ....................................................................67 5.4 Conclusions......................................................................................78

    REFERENCES .................................................................................79

    6 Biodegradation in soil of a model polyester: process description and attempt of carbon balance..........................................................................81

    ABSTRACT......................................................................................81 6.1 Introduction......................................................................................82 6.2 Materials and Methods.....................................................................82

    6.2.1 The tested substances ................................................................82 6.2.2 Biodegradation test....................................................................83 6.2.3 Organic matter determination....................................................85 6.2.4 Soil extraction ...........................................................................85 6.2.5 GPC measurement.....................................................................85 6.2.6 NMR acquisition .......................................................................86

    6.3 Results and Discussion ....................................................................87 6.3.1 Model polyester characterization ..............................................87 6.3.2 Mineralization, organic matter determination and analytical analysis..................................................................................................90 6.3.3 Carbon balance..........................................................................96

    6.4 Conclusions......................................................................................98 REFERENCES ...............................................................................100

    7 Conclusions .........................................................................................103 REFERENCES ...............................................................................105

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    1 Study of the biodegradation in soil of new generation plastics

    1.1 Introduction Plastic derives from the Greek words (plastikos) or (plastos) meaning fit for moulding or moulded respectively. It refers to the material malleability, or plasticity during manufacture, that allows it to be cast, pressed, or extruded into a large variety of shapes (films, fibres, tubes, bottles, boxes). Humanity first used natural materials with plastic properties (e.g., clay, amber, arabic rubber, caucci), then developed chemically modified natural materials (e.g., rubber, nitrocellulose, collagen) and, finally (around 100 years ago), developed the wide range of completely synthetic materials that, nowadays, we recognise as modern plastics. In the mid-nineteenth century the Parkesine and the polyvinyl chloride (PVC) were invented. The first is the earliest example of synthetic polymer today known as celluloid, the second is the third most widely produced plastic after polyethylene and polypropylene. Nevertheless Leo Baekeland marked a turning point by creating, in 1907, the Bakelite (a condensation product of phenol and formaldehyde) that is considered the first real synthetic man-made plastic. The first decades of the twentieth century saw the invention and the production of the first plastic packaging material (cellophane) and of the first coloured plastic, obtained combining formaldehyde, carbon dioxide and ammonia with coloured powder. Nylon was first synthesized in 1935; polystyrene, polyethylene, polyethylene-terephthatate and silicones (widely used today) were developed during the second world war period. In 50s nylon and lycra became a major force in the clothing industry and decorative laminates, such as formica, were widely used (www.plasticseurope.org). Plastic is relatively low cost and easy to be ma