Robin Treilles a , A. Cayla b,c , J. Gasperi a , B. Strich c , P. Ausset d and B. Tassin a a University of Paris-Est, LEESU, France b University of Lille Nord de France, Lille, France c ENSAIT, GEMTEX, Roubaix, France d University of Paris-Est Créteil, LISA, France robin.treilles@enpc.fr Microplastics 2018, October 30th, Ascona, Switzerland 1
Digestion protocols are used to dissolve organic matter in environmental samples. In recent works, we observe three important points: 1. Fibers correspond to the greater fraction of microplastics in water samples. Washing Surface Rain Waters Machine Waters Effluents Fibers 20 - 40 9,000 - 35,000 0.03 - 0.05 (Item/Liter) Fragments Not observed < 2 0.001 - 0.003 (Item/Liter) Picture from Soline Alligant Table from ASTEE Presentation, Tassin et al., 2018 2. Quality Assurance/Quality Control ( QA/QC ) for digestion protocols are more and more developed for fragments but not for fibers. 3. Impacts of digestion protocols on fibers? Microplastics 2018, October 30th, Ascona, Switzerland 2
The most commonly used fibers (Raw fibers) Chemical Fibers Natural Fibers Vegetable Artificial Cotton Viscose Flax Animal Synthetic PET Wool PA 6.6 Acrylic Microplastics 2018, October 30th, Ascona, Switzerland 3
Four different digestion protocols have been selected: KOH 10%, 40 ° C, 24h (Dehaut et al., 2016) KOH 10%, 60 ° C, 24h (Karami et al., 2017) H 2 O 2 30%, 50 ° C, 48h (Stolte et al., 2015) NaClO 9%, ambient temperature, one night (Collard et al., 2015) After digestion and filtration Microplastics 2018, October 30th, Ascona, Switzerland 4
Fibers Caracterisation before and after digestion 1 2 3 Morphological Mechanical Thermal and aspects Properties Chemical Properties • Mass variation • Linear mass • Differential density Scannning • Microscope Calorimetry observation: • Tenacity = (DSC) Optical Breaking strain Scanning • Infrared Electron • Elongation at Spectroscopy Microscope break (FTIR) Microplastics 2018, October 30th, Ascona, Switzerland 5
s: Flax Flax 6 After digestion NaClO 9%, Ambient temperature 100 µm 100 µm Flax, Microscope x 40, before and after NaClO digestion Microplastics 2018, October 30th, Ascona, Switzerland 6
s: PET PET ~20 µm After digestion < 10 µm KOH 10% 60°C 24 hours 100 µm 100 µm PET, Microscope x 40, before and after KOH 60 ° C digestion Microplastics 2018, October 30th, Ascona, Switzerland 7
Results: 250 µm 25 µm After digestion Increase of surface KOH 10% 60°C roughness 24 hours 10 µm 10 µm 8 Microplastics 2018, October 30th, Ascona, Switzerland
• PET is strongly affected by KOH 60 ° C digestion (~70 % of mass loss), high degradation is confirmed with SEM. 250 µm 25 µm After digestion • Flax hull is shattered by NaClO digestion . KOH 10% 60° SEM analysis will complete this observation. 24 hours • Wool is totally dissolved , except for H 2 O 2 . 10 µm 10 µm 9 Microplastics 2018, October 30th, Ascona, Switzerland
120 Tenacity (cN/Tex) 100 80 60 40 20 0 PET PA 6.6 Acrylic Viscose Flax Cotton 5 Elongation at break (%) 4 3 2 1 0 -1 Before Dig KOH 40°C KOH 60°C NaClO H2O2 Microplastics 2018, October 30th, Ascona, Switzerland 10
120 Tenacity (cN/Tex) 100 80 60 40 20 0 Mean ± standard deviation PET PA 6.6 Acrylic Viscose Flax Cotton N = 30 for non digested fibers 5 Elongation at break (%) 4 N = 3 to 5 for digested fibers 3 2 1 0 -1 Before Dig KOH 40°C KOH 60°C NaClO H2O2 Microplastics 2018, October 30th, Ascona, Switzerland 11
120 Tenacity (cN/Tex) 100 80 60 40 20 0 PET PA 6.6 Acrylic Viscose Flax Cotton 5 Elongation at break (%) 4 3 2 1 0 -1 Before Dig KOH 40°C KOH 60°C NaClO H2O2 Microplastics 2018, October 30th, Ascona, Switzerland 12
120 Tenacity (cN/Tex) 100 80 60 40 20 0 PET PA 6.6 Acrylic Viscose Flax Cotton 5 Elongation at break (%) 4 3 2 1 0 -1 Before Dig KOH 40°C KOH 60°C NaClO H2O2 Microplastics 2018, October 30th, Ascona, Switzerland 13
120 Tenacity (cN/Tex) 100 80 60 40 • PET becomes too brittle with KOH 60 ° C digestion to 20 0 be studied. The mechanical properties of the flax are PET PA 6.6 Acrylic Viscose Flax Cotton also affected by this digestion. 5 Elongation at break (%) • Viscose becomes too brittle with H 2 O 2 digestion to 4 be studied. This digestion affects the mechanical 3 properties of PA 6.6, flax and cotton . 2 1 0 -1 Before Dig KOH 40°C KOH 60°C NaClO H2O2 Microplastics 2018, October 30th, Ascona, Switzerland 14
PET FTIR Spectra Optical density Wavenumber (cm -1 ) Blue curve : before KOH 10 % 60 ° C digestion Red curve : after KOH 10% 60 ° C digestion Microplastics 2018, October 30th, Ascona, Switzerland 15
PET FTIR Spectra Optical density Wavenumber (cm -1 ) Blue curve : before KOH 10 % 60 ° digestion Red curve : after KOH 10% 60 ° digestion Microplastics 2018, October 30th, Ascona, Switzerland 16
1 = Not affected PET PA 6.6 2 = Slightly affected Mass Mass 3 = Affected Modification Modification 4 4 4 = Very affected 3 3 2 KOH 40°C 2 Elongation Linear Mass Elongation Linear Mass 1 at break 1 Density at break Density KOH 60°C 0 0 NaClO H2O2 Microscope Microscope Tenacity Tenacity Observation Observation Acrylic Viscose Mass Mass Modification Modification 4 4 3 3 KOH 40°C 2 2 Elongation Linear Mass Elongation Linear Mass at break 1 Density at break 1 Density KOH 60°C 0 0 NaClO H2O2 Microscope Microscope Tenacity Tenacity Observation Observation Microplastics 2018, October 30th, Ascona, Switzerland 17
Flax Cotton Mass Mass Modification Modification 4 4 3 3 KOH 40°C 2 2 Elongation Linear Mass Elongation Linear Mass at break 1 Density at break 1 Density KOH 60°C 0 0 NaClO H2O2 Microscope Microscope Tenacity Tenacity Observation Observation Number of criteria > 3 PET PA 6.6 Acrylic Viscose Wool Flax Cotton KOH 40°C 0 1 0 0 5 0 0 KOH 60°C 5 1 0 0 5 1 0 NaClO 0 1 0 0 5 1 0 H2O2 0 1 0 2 5 0 0 Microplastics 2018, October 30th, Ascona, Switzerland 18
Strongly affected by PET Totally Dissolved, KOH 10% 24h 60°C Wool except with H2O2 Affected by H 2 O 2 Viscose but 30% 48h 50°C Ok except with Flax NaClO Slightly Affected by PA all digestion protocols Microplastics 2018, October 30th, Ascona, Switzerland 19
• More observations with KOH 40 ° C digestion seems the SEM more relevant for 6 types of fibers. • Fenton’s reagent ? Enzymatic digestion ? T > 60°C Not recommended • What will happen with Which Which environmental fibers ? Digestion ? Fibers ?! Microplastics 2018, October 30th, Ascona, Switzerland 20
10 µm 10 µm Microplastics 2018, October 30th, Ascona, Switzerland 21
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