Contents List of figures ix List of tables xix Foreword xxi Acknowledgement xxiii Abbreviations xxv 1.Background introduction 1 1.1 Current situation and hazards of plastic waste 1 1.1.1 Pollution to the natural environment 2 1.1.2 A threat to human health 4 1.1.3 Cause a waste of resources 5 1.2 Traditional treatment methods6 1.2.1 Landfill treatment 7 1.2.2 Mechanical recovery 7 1.2.3 Incineration method 8 1.2.4 Thermal decomposition 8 1.3 Supercritical water technology 9 1.3.1 Supercritical water characteristics 9 1.3.2 Resource utilization of waste plastics in supercritical water 10 References 20 2.Analysis of types of plastics 29 2.1 Introduction to raw materials 29 2.1.1 Polycarbonate plastic 29 2.1.2 Polypropylene plastic 29 2.1.3 Acrylonitrile butadiene styrene plastic 29 2.1.4 Polyethylene terephthalate plastic 31 2.1.5 High-impaa polystyrene plastic 31 2.1.6 Polystyrene plastic 31 2.1.7 Polyethylene plastic 32 2.1.8 Urea—formaldehyde plastic 32 2.1.9 Circuit board 32 2.1.10 Lignite 33 2.1.11 Soda lignin 33 2.1.12 Artificial seawater 33 2.1.13 Formic add and hydrochloric acid solvent 33 2.2 Material characterization 34 2.2.1 Elemental and proximate analysis 34 2.2.2 Thermogravimetric analysis 34 2.3 Experimental bench 40 2.3.1 Quartz tube reactor 40 2.3.2 Batch kettle reactor 41 2.4 Product analysis 42 2.4.1 Gas phase products 42 2.4.2 Liquid phase products 43 2.4.3 Solid phase products 45 References 46 3.Resource utilization of thermoplastics in supercritical water 47 3.1 Gasification 47 3.1.1 Experimental investigation on gasification characteristics of polycarbonate microplastics in supercritical water 47 3.1.2 Experimental study on gasification performance of polypropylene plastics in supercritical water 58 3.1.3 Experimental investigation on in-situ hydrogenation induced gasification characteristics of acrylonitrile butadiene styrene
microplastics in supercritical water 74 3.1.4 Experimental investigation on gasification characteristics of polyethylene terephthalate microplastics in supercritical water 85 3.1.5 Experimental investigation on gasification characteristics of high impact polystyrene plastics in supercritical water 99 3.2 Liquefaction 110 3.2.1 Hydrothermal liquefaction of polycarbonate plastics in sub-/supercritical water and an exploration of reaction pathways 110 3.3 Liquefaction reaction pathways exploration 123 3.3.1 Liquefaction kinetics of polycarbonate 126 3.4 Carbon dioxide fixation 141 3.4.1 In the supercritical water/C02 environment 141 3.4.2 In C02 environment 147 3.5 Coordinated treatment of pollutants 157 3.5.1 Hydrogen/methane production from supercritical water gasification of lignite coal with plastic waste blends 157 3.5.2 Cogasification of plastic wastes and soda lignin in supercritical water 169 3.6 Preparation of hydrophobic materials 182 3.6.1 Hydrophobic behavior 183 3.6.2 Microstructure 186 3.6.3 Functional groups 191 References 193 4.Resource utilization of thermosetting plastics in supercritical water 201 4.1 Hydrogen-rich syngas production by gasification of urea—formaldehyde plastics in supercritical water 201 4.1.1 Effect of reaction temperature 201 4.1.2 Effect of reaction time 202 4.1.3 Effect of feedstock mass fraction 203 4.1.4 Effect of reaction pressure 204 4.1.5 Compared with the polystyrene plastics 205 4.1.6 Reaction analysis 207 4.1.7 Kinetic study 207 4.1.8 Conclusions 209 4.2 Resource utilization of circuit boards 210 4.2.1 Effect of reaction temperature 210 4.2.2 Effect of the reaction time 215 4.2.3 Effect of feedstock concentration 219 4.2.4 Effect of additive 220 4.2.5 Conclusion 222 References 223 5.Development prospects for resource utilization of waste plastics 227 5.1 Necessity of recycling waste plastics 227 5.1.1 Biodiversity conservation 228 5.1.2 Maintaining soil fertility 229 5.1.3 Saving resources 231 5.2 Comprehensive treatment countermeasures of waste plastics 232 5.2.1 Policy 232 5.2.2 General situation of domestic and foreign waste plastic treatment 237 5.2.3 Existing shortcomings 239 5.2.4 Improvement measures 240 5.3 Prospect of waste plastics treatment with supercritical water 242 5.3.1 Existing problems 243 5.3.2 Future development direction 244 References 245 Index 249 List of figures Figure 1.1 Global annual production of plastic.1 Figure 1.2 The transfer of microplastic in different environments.3 Figure 1.3 The formation and influence of microplastic in the ocean.3 Figure 1.4 Main treatment methods for waste plastic.6 Figure 2.1 Chemical structure of(A)BPA;(B)DPC;(C)PC.BPA,bisphenol A;30 DPC,diphenyl carbonate;PC,polycarbonate. Figure 2.2 Molecular structure of ABS plastic here.ABS,acrylonitrile butadiene styrene.30 Figure 2.3 Chemical structure of polyethylene terephthalate(PET).31 Figure 2.4 Molecular structure of HIPS plastic.HIPS,high-impact polystyrene.31 Figure 2.5 Molecular structure of PS plastic.PS,polymer synthesized.32 Figure 2.6 Chemical structures of(A)hydroxymethylurea;(B)1,3-32 bishydroxymethylurea;(C)tri-hydroxymethylurea;and(D,E)UF
plastics.UF,urea-formaldehyde. Figure 2.7 Molecular structure of tetrabromobisphenol A EP.EP,epoxy resin.33 Figure 2.8 TGA of PC plastic.PC,polycarbonate;TGA,thermogravimetric analysis.35 Figure 2.9 TGA of PP plastic.PP,polypropylene;TGA,thermogravimetric analysis.36 Figure 2.10 TGA of ABS plastic.ABS,acrylonitrile butadiene styrene;TGA,36 thermogravimetric analysis. Figure 2.11 TGA of PET plastic.TGA,thermogravimetric analysis;PET,polyethylene 37 terephthalate. Figure 2.12 TGA of HIPS plastic.HIPS,high-impact polystyrene;TGA,37 thermogravimetric analysis. Figure 2.13 TGA of PS plastic.PS,polymer synthesized;TGA,thermogravimetric 38 analysis. Figure 2.14 Thermogravimetric curve of polyethylene(PE)plastic.39 Figure 2.15 Steam gasification curve for the discarded circuit boards.39 Figure 2.16 Schematics of the supercritical water gasification(SCWG)experiment.40 Figure 2.17 The schematic diagram of liquid product collection.41 Figure 2.18 A simple system to take photos of inner surface droplets.45 Figure 3.1 Effect of reaction temperature on microplastics gasification:(A)CE/ 48 hydrogen conversion rate(HE);(B)gas fraction
concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.3 Effect of reaction time on microplastics gasification:(A)CE/HE;(B)gas 50 fraction(C2Hx,x=4,6)(temperature 700oC;pressure 23
MPa;feedstock concentration 5 wt.%)here. Figure 3.4 Microplastics residual liquid component at different reaction times:GC/MS 50(temperature 700oC;pressure 23 MPa;feedstock
concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.5 Effect of feedstock concentration on microplastics gasification:(A)CE/HE;51 (B)gas fraction(C2Hx,x=4,6)(temperature 700oC;time 10 min;pressure 23 MPa)here. Figure 3.6 Effect of reaction pressure on microplastics gasification:(A)CE/HE;(B)gas 52 fraction(C2Hx,x=4,6)(temperature 700oC;time 10
min;feedstock concentration 5 wt.%)here. Figure 3.7 Effect of seawater components on microplastics gasification:(A)CE/HE;53 (B)gas fraction(C2Hx,x=4,6)(temperature 700oC;time 10 min;feedstock concentration 5 wt.%)here. Figure 3.8 Plastic residual solid products with different Seawater components:(A)55 SCW;(B)KCl;(C)NaCl;(D)CaCl2;(E)MgCl2;(F)Na2SO4;(G)
NaHCO3;(H)seawater(temperature 700oC,pressure 23 MPa;time 10 min;feedstock concentration 5 wt.%)here.SCW,Supercritical water. Figure 3.9 Effect of reaction time on microplastics gasification:(A)CE/HE;(B)gas 56 yield(C2Hx,x=4,6)(pressure 23 MPa;feedstock
concentration 5 wt.%)here. Figure 3.10 Effect of reaction temperature on gasification:(A)CE/HE;(B)gas fraction.59(C2Hx,x=4,6)(time 10 min;pressure 23
MPa;feedstock concentration 5 wt.%)here. Figure 3.11 Residual liquid components at different reaction temperatures:GC/MS 60(time 10 min;pressure 23 MPa;feedstock concentration
5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.12 Effect of reaction time on gasification:(A)CE/HE;(B)gas fraction(C2Hx,61 x=4,6)(temperature 700oC;pressure 23 MPa;feedstock
concentration 5 wt.%)here. Figure 3.13 Residual liquid component at different reaction times:GC/MS 61(temperature 700oC;pressure 23 MPa;feedstock concentration 5
wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.14 Effect of feedstock concentration on gasification:(A)CE/HE;(B)gas 62 fraction(C2Hx,x=4,6)(temperature 700oC;time 10
min;pressure 23 MPa)here. Figure 3.15 Effect of seawater components on gasification:(A)CE/HE;(B)gas 63 fraction.(C2Hx,x=4,6)(temperature 700oC;time 10
min;feedstock concentration 5 wt.%)here. Figure 3.16 Residual solid products at different conditions:(A)SCW;(B)seawater.64(temperature 700oC,pressure 23 MPa;time 10
min;feedstock concentration 5 wt.%)here.SCW,Supercritical water. Figure 3.17 Gasification reaction mechanism of PP plastic in SCW here.PP,65 Polypropylene;SCW,supercritical water. Figure 3.18 Gas yield prediction with the kinetic model:(A)650oC;(B)700oC;(C)70 750oC(solid,experiment data;hollow,predicted
data;pressure 23 MPa;feedstock concentration 5 wt.%)here. Figure 3.19 The CE of plastics with different reaction factors:(A)CE/HE;(B)RSM 71(temperature 650oC-750oC;time 2-60 min;feedstock
concentration 5 wt.%)here.RSM,Response surface methodology. List of figures Figure 3.20 Plastics gasification with different reaction modes:(A)CE/HE;(B)gas 73 fraction(temperature 750oC;feedstock concentration 5
wt.%)(SCW:supercritical water;ST:steam;FA:SCW with formic acid;PY:pyrolysis)(The number on the sample represents the reaction time,such
as the10 in SCW10 means a reaction time of 10 min)here. Figure 3.21 Effect of reaction temperature on microplastics gasification:(A)CE/HE;75(B)gas fraction(C2Hx,x=4,6)(time 10 min;pressure 23
MPa;feedstock concentration 5 wt.%)here. Figure 3.22 Plastic residual liquid component at different reaction temperatures:GC/ 75 MS(time 10 min;pressure 23 MPa;feedstock
concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.23 Effect of reaction time on microplastics gasification:(A)CE/HE;(B)gas 76 fraction(C2Hx,x=4,6)(temperature 700oC;pressure 23
MPa;feedstock concentration 5 wt.%)here. Figure 3.24 Plastic residual liquid component at different reaction times:GC/MS 77(temperature 700oC;pressure 23 MPa;feedstock
concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.25 Effect of feedstock concentration on microplastics gasification:(A)CE/HE;78(B)gas fraction(C2Hx,x=4,6)(temperature
700oC;time 10 min;pressure 23 MPa)here. Figure 3.26 Effect of reaction pressure on microplastics gasification:(A)CE/HE;(B)gas 79 fraction(C2Hx,x=4,6)(temperature 700oC;time 10
min;feedstock concentration 5 wt.%)here. Figure 3.27 Effect of different conversion modes on microplastics gasification:(A)CE/ 80 HE;(B)gas fraction.(Pyrolysis,PY;Supercritical
water,SCW;Hydrochloric acid,HCl;Formic acid,FA)(temperature 800oC;feedstock concentration 5 wt.%)here. Figure 3.28 Plastic residual liquid component at different conversion mode:GC/MS;81(A)400oC;(B)700oC(Pyrolysis,PY;Supercritical
min)here. Figure 3.31 Effect of reaction temperature on PET microplastics gasification:(A)86 CE/HE;(B)gas fraction(C2Hx,x=4,6)(time 10 min;pressure 23 MPa;feedstock concentration 5 wt.%)here.PET,polyethylene terephthalate. Figure 3.32 PET microplastics residual liquid component at different reaction 86 temperatures:GC/MS(time 10 min;pressure 23
MPa;feedstock concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry;PET,polyethylene terephthalate. Figure 3.33 Effect of reaction time on PET microplastics gasification:(A)CE/HE;(B)87 gas fraction(C2Hx,x=4,6)(temperature
700oC;pressure 23 MPa;feedstock concentration 5 wt.%)here.PET,Polyethylene terephthalate. Figure 3.34 PET microplastic residual liquid component at different reaction times:88 GC/MS;(temperature 700oC;pressure 23
MPa;feedstock concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry;PET,polyethylene terephthalate. Figure 3.35 Effect of reaction pressure on PET microplastics gasification:(A)CE/HE;89(B)gas fraction(C2Hx,x=4,6)(temperature 700oC;time
10 min;feedstock concentration 5 wt.%)here.PET,Polyethylene terephthalate. Figure 3.36 Effect of seawater components on microplastics gasification:(A)CE/HE;90(B)gas fraction(C2Hx,x=4,6)(temperature 700oC;time
10 min;feedstock concentration 5 wt.%)here. Figure 3.37 Gasification reaction mechanism of PET microplastics in SCW here.PET,92 Polyethylene terephthalate;SCW,supercritical water. Figure 3.38 Effect of reaction time on microplastics gasification(pressure 23 MPa;93 feedstock concentration 5 wt.%)here. Figure 3.39 Changes of gas components with increasing reaction time:(A)675oC,(B)97 700oC,(C)725oC(Hollow symbol:calculated value;Solid
symbol:experimental value)here. Figure 3.40 Effect of reaction time on plastic gasification:(A)CE/HE;(B)gas yield.99(temperature 700oC;pressure 23 MPa;feedstock
concentration 5 wt.%)here.Figure 3.41 Plastic residual liquid component at different reaction times:(A)GC/MS;100(B)liquid component
(temperature 700oC;pressure 23 MPa;feedstock concentration 5 wt.%)here.EDS,Energy-dispersive X-ray spectroscopy. Figure 3.43 Effect of reaction temperature on plastic gasification:(A)CE/HE;(B)gas 103 yield(time 10 min;pressure 23 MPa;feedstock
concentration 5 wt.%)here. Figure 3.44 Plastic residual liquid component at different reaction temperatures:(A)104 GC/MS;(B)liquid component yield(time 10
min;pressure 23 MPa;feedstock concentration 5 wt.%)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.45 Plastic residue morphology at different reaction temperatures:(A)500oC;105(B)600oC;(C)700oC;(D)800oC(time 10 min;pressure
23 MPa;feedstock concentration 5 wt.%)(E)pyrolysis 700oC,10 min;(F)pyrolysis 700oC,30 min here. Figure 3.46 Effect of feedstock concentration on plastic gasification:(A)CE/HE;(B)106 gas yield(temperature 700oC;time 10 min;pressure
23 MPa)here. Figure 3.47 Effect of reaction pressure on plastic gasification:(A)CE/HE;(B)gas yield 107(temperature 700oC;time 10 min;feedstock
concentration 5 wt.%)here.
List of figures xiii Figure 3.48 Optimal conditions for plastic gasification:(A)CE/HE;(B)gas yield 108 (temperature 800oC;pressure 23 MPa;feedstock concentration 3 wt.%)here. Figure 3.49 Plastic residue morphology at optimal conditions for plastic gasification:(A)109 30 min;(B)60 min(temperature 800oC;pressure 23 MPa;feedstock concentration 3 wt.%)here. Figure 3.50 The liquefaction products of PC:GC/MS(temperature 400oC;time 111 35 min;feedstock concentration 10 wt.%)here.GC,gas chromatography;MS,mass spectrometry;PC,polycarbonate. Figure 3.51 The contour map of CLE at a feed concentration of(A)5 wt.%,(B)10 wt.114 %,and(C)15 wt.% here.CLE,Carbon liquefaction. Figure 3.52 The contour map of CLE at a reaction time of(A)10 min,(B)30 min,and 114 (C)60 min here.CLE,Carbon liquefaction. Figure 3.53 The contour map of CLE at a temperature of(A)300oC,(B)400oC,and 115 (C)500oC here.CLE,Carbon liquefaction. Figure 3.54 Content of components at different concentrations(temperature 400oC;117 time 30 min)here. Figure 3.55 The contour map of REphenol at a feed concentration of(A)5 wt.%,(B)117 10 wt.%,and(C)15 wt.% here.RE,Recovery efficiency. Figure 3.56 The contour map of REIPP at feed concentrations of(A)5 wt.%,(B)118 10 wt.%,and(C)15 wt.% here.RE,Recovery efficiency. Figure 3.57 The contour map of REIPrP at a feed concentration of(A)5 wt.%,(B)118 10 wt.%,and(C)15 wt.% here.RE,Recovery efficiency. Figure 3.58 RE distribution of identified liquefied products at a 5 wt.% of feedstock 122 concentration here.RE,Recovery efficiency. Figure 3.59 LS of products at a 5 wt.% of feedstock concentration here.LS,123 Liquefaction selectivity. Figure 3.60 Liquefaction mechanism of PC here.PC,Polycarbonate.125 Figure 3.61 Changes of liquefied products at 400oC with time(Line:calculated value;130 Symbol:experimental value)here. Figure 3.62 Comparison of calculation results from the model with experimental data 130 here. Figure 3.63 Liquefaction efficiency of PC based on the model(Temperature,400oC)131 here.PC,Polycarbonate. Figure 3.64 Plastic residual liquid component at different reaction temperatures(time 132 10 min;pressure 30 MPa;feedstock concentration 5 wt.%).(Red color)400oC;(Black color)500oC here. Figure 3.65 Effect of reaction temperature on plastic liquefaction(pressure 30 MPa;133 feedstock concentration 5 wt.%;time 10 min).(*)Ethylbenzene;(*)Toluene;(*)Isopropylbenzene;(*)Styrene;(*)α-Methylstyrene;(*)
Naphthalene;(*)Biphenyl;(*)1,3- Diphenylpropane;(*)2-Phenylnaphthalene;(*)CLE here.CLE,Carbon liquefaction. Figure 3.66 Liquid-phase components in SCW and PY(SCW:pressure 30 MPa;136 temperature 490oC;feedstock concentration 5 wt.%;time 10 min.PY:Pressure,atmospheric pressure;temperature 490oC;time 10 min).(*)
Phenylnaphthalene;(*)CLE here.CLE,Carbon liquefaction;PY,pyrolysis;SCW, supercritical water. Figure 3.67 Effect of reaction time on plastic liquefaction(pressure 30 MPa;137 temperature 400oC;feedstock concentration 5 wt.%).(*)Ethylbenzene;(*)Toluene;(*)Isopropylbenzene;(*)Styrene;(*)α-Methylstyrene;(*)
Naphthalene;(*)Biphenyl;(*)1,3-Diphenylpropane;(*)2-Phenylnaphthalene;(*)CLE here.CLE,Carbon liquefaction. Figure 3.68 Effect of reaction pressure on plastic liquefaction(temperature 400oC;139 feedstock concentration 5 wt.%;time 10 min).(*)Ethylbenzene;(*)Toluene;(*)Styrene;(*)α-Methylstyrene;(*)1.3- Diphenylpropane;(*)CLE
here.CLE,Carbon liquefaction. Figure 3.69 Effect of reaction feedstock concentration on plastic liquefaction(pressure 140 30 MPa;temperature 400oC;time 10 min).(*)Ethylbenzene;(*)Toluene;(*)Styrene;(*)α-Methylstyrene;(*)1,3- Diphenylpropane;(*)CLE
here.CLE,Carbon liquefaction. Figure 3.70 Effect of the presence of CO2:(A)CE/HE;(B)Gas fraction;(C)gas yield 142 (C2Hx,x=4,6)(temperature 700oC;pressure during the reaction 23-29 MPa,time 20 min)here. Figure 3.71 Effect of reaction temperature:(A)CE/HE;(B)Gas fraction;(C)gas yield 143 (C2Hx,x=4,6)(time 20 min;pressure during the reaction 23-29 MPa;CO2 volume 220 mL;the mass of water added at 400oC,500oC,600oC,and
700oC is 4.2,3.85,3.75,and 3.6 g,respectively)here. Figure 3.72 Plastic residual liquid component at different reaction temperatures:(A)144 GC/MS;(B)relative peak areas of liquid components(time 20 min;CO2 volume 220 mL)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.73 The results of fourier transform infrared spectrum of feedstocks and the 145 solid products here. Figure 3.74 Plastic residue morphology at different reaction temperatures:(A)400oC;146 (B)500oC;(C)600oC;(D)700oC here. Figure 3.75 Effect of reaction time:(A)CE/HE;(B)gas fraction;(C)gas yield(C2Hx,147 x=4,6)(temperature 700oC;pressure during the reaction 23-29 MPa;water quality 3.6 g;CO2 volume 220 mL)here. Figure 3.76 Plastic residual liquid components at different reaction times:(A)GC/MS;148 (B)relative peak areas of liquid components(temperature 700oC;water quality 3.6 g;CO2 volume 220 mL)here.GC,gas chromatography;MS,mass
spectrometry. Figure 3.77 Plastic residue morphology at different reaction times:(A)0 min;(B)149 10 min;(C)20 min;(D)30 min here. Figure 3.78 Effect of CO2 concentration:(A)CE/HE and CO2 consumption;(B)gas 150 yield(C2Hx,x=4,6)(temperature 700oC;time 20 min;pressure during the reaction 3-10 MPa)here.List of figures Figure 3.79 Plastic residual liquid component at different CO2 concentrations:(A)GC/ 151 MS;(B)relative peak areas of liquid components(temperature 700oC;time 20 min)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.80 Effect of reaction temperature:(A)CE/HE and CO2 consumption;(B)gas 152 yield(C2Hx,x=4,6)(time 20 min;CO2 volume 340 mL)here. Figure 3.81 Plastic residual liquid component at different temperatures:(A)GC/MS;153 (B)Relative peak areas of liquid components(time 20 min;CO2 volume 340 mL)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.82 Plastic residue morphology at different reaction temperatures:(A)400oC;154 (B)500oC;(C)600oC;(D)700oC here. Figure 3.83 Effect of reaction time:(A)CE/HE and CO2 consumption;(B)Gas yield 154 (C2Hx,x=4,6)(temperature 700oC;CO2 volume 340 mL)here. Figure 3.84 Plastic residual liquid components at different reaction times:(A)GC/MS;155 (B)Relative peak areas of liquid components(temperature 700oC;CO2 volume 340 mL)here.GC,gas chromatography;MS,mass spectrometry. Figure 3.85 Plastic residue morphology at different reaction times:(A)0 min;(B)157 10 min;(C)20 min;(D)30 min here. Figure 3.86 Influence of lignite/plastics mixing ratio on(A)CE,GE,and(B)gas yield 159 from the cogasification at 700oC(total concentration:10 wt.%;30 min)here. Figure 3.87 Influence of reaction temperature on the(A)CE,GE,HE,and(B)a gas 163 fraction from SCWG of lignite/PP blends(mixing ratio:50:50;total concentration:10 wt.%;reaction time:30 min)here.SCWG,supercritical
water gasification. Figure 3.88 Influence of the total concentration of lignite and PP on(A)CE,GE,HE,164 (B)gas fraction and H2 yields from cogasification at 700oC(mixing ratio:50:50;reaction time:30 min)here. Figure 3.89 Influence of reaction time on the(A)CE,GE,HE,and(B)gas fraction 165 and H2 yield from SCWG of lignite/PP blends(1:1)at 700oC(total concentration:10 wt.%)here.SCWG,supercritical water gasification. Figure 3.90 Influence of reaction time on the GC-MS spectra of liquid products from 166 SCWG of lignite/PP blends(1:1)at 700oC(total concentration:10 wt.%)here.GC,gas chromatography;MS,mass
spectrometry;PP,polypropylene;SCWG,supercritical water gasification. Figure 3.91 Quartz reactors and SEM images of the solid residues from the gasification 167 of lignite/PP blends at 700oC for(A)5 min and(B)30 min and(C)the energy-dispersive X-ray spectroscopy of solid residues obtained at 30
min here.PP,polypropylene;SEM,scanning electron microscope. Figure 3.92 Influence of mixing ratio of soda lignin/PE on(A)the GE and CE and(B)169 gas fraction of the cogasification at 700oC(total concentration:10 wt.%;reaction time:30 min).The dotted line in left figure represents
the theoretical GE and CE of the mixture here.PE,Polyethylene. Figure 3.93 Influence of NaOH on(A)the CE,HE,GE,and(B)gas fraction from 170 SCWG of PE at 700oC(PE concentration:10 wt.%;NaOH concentration:1 wt.%;reaction time:30 min)here.PE,polyethylene;SCWG,supercritical
water gasification. Figure 3.94 The main components in the liquid products from separate gasification and 172 cogasification of soda lignin and PE at 700oC(mixing ratio:50:50;total concentration:10 wt.%;reaction time:30 min)here.PE,Polyethylene. Figure 3.95 Influence of reaction temperature on(A)the GE,CE,HE and(B)the gas 173 yields of cogasification of soda lignin/PE with a mixing ratio of 50:50(total concentration:10 wt.%;reaction time:30 min)
here.PE,olyethylene. Figure 3.96 Influence of temperature on the main composition of the liquid products 174 from cogasification of soda lignin/PE with a mixing ratio of 50:50(total concentration:10 wt.%;reaction time:30 min)here. Figure 3.97 Influence of reaction time on(A)the GE,CE,and HE and(B)gas yield 175 from cogasification of soda lignin/PE at 700oC(mixing ratio:50:50;total concentration:10 wt.%)here. Figure 3.98 Influence of reaction time on the GC/MS spectra of liquid products from 176 cogasification of soda lignin/PE at 700oC.(mixing ratio:50:50;total concentration:10 wt.%)here.GC,gas chromatography;MS,mass
spectrometry;PE,polyethylene. Figure 3.99 Influence of total concentration on(A)gasification efficiencies and(B)gas 177 composition from cogasification of soda lignin/PE at 700oC(mixing ratio:50:50;reaction time:30 min)here.PE,Polyethylene. Figure 3.100 Interaction mechanism of soda lignin and PE in SCWG here.PE,178 polyethylene;SCWG,supercritical water gasification. Figure 3.101(A)comparison between blank tubes and processed samples(upright and 182 upside-down position);(B)cut pieces of tubes here. Figure 3.102 The state of the inner surface made from PS processed in SCW at different 183 temperatures but the same pressure 23 MPa;(A)blank control;(B)600oC;(C)650oC;(D)700oC;(E)750oC;(F)800oC
here.PS,polystyrene;SCW,supercritical water. Figure 3.103 Hydrophobic behavior comparison between blank control and SCW 184 processed samples at different temperatures here.SCW,supercritical water. Figure 3.104 The state of the inner surface made from PS processed in SCW for a 184 different time but the same pressure 23 MPa;(A)5 min;(B)10 min;(C)20 min;(D)30 min here.PS,polystyrene;SCW,supercritical water. Figure 3.105 Hydrophobic behavior comparison between blank tube and SCW 184 processed samples at different times here.SCW,supercritical water. Figure 3.106 The state of the inner surface made from different plastics,but all processed in 185 23 MpaSCW for10 min;(A)PS;(B)PC;(C)PE here.PE,polyethylene;PC,polycarbonate;PS,polystyrene;SCW,supercritical water. Figure 3.107 A comparison of micro characterization;PS-SCW-600oC-10 min sample;186 (A)SEM;(B)EDS here.EDS,elemental dispersive spectrometer;PS,polystyrene;SCW,supercritical water;SEM,scanning electron microscope. Figure 3.108 SEM characterization images of PS processed in 23 MPa SCW for 10 min 187 but at different temperatures;(A)600oC;(B)650oC;
(C)700oC;(D)750oC;(E)800oC here.PS,Polystyrene;SCW,supercritical water;SEM,scanning electron microscope.List of figures xvii Figure 3.109 Particle size distribution of CSs produced from PS processed in SCW at 188 different temperatures;(A)650oC;(B)700oC;(C)750oC;(D)800oC here.CS,carbon sphere;PS,polystyrene;SCW,supercritical water. Figure 3.110 Chat showing that the size of CSs varied with reaction temperature:(A)189 connection between average diameter and standard deviation;(B)connection between average diameter and maximum CA here.CA,contact
angle;CS,carbon sphere. Figure 3.111 SEM characterization images of PS processed in 23 MPa,700oC SCW for 189 different times;(A)20 min;(B)30 min here.PS,polystyrene;SCW,supercritical water;SEM,scanning electron microscope. Figure 3.112 Particle size distribution of CSs produced from PS processed in SCW for 189 different times;(A)20 min;(B)30 min here.CS,carbon sphere;PS,polystyrene;SCW,supercritical water. Figure 3.113 Comparison between CA and average diameter in series experiments of 190 time variable here.CA,contact angle. Figure 3.114 SEM characterization images of plastics processed in 23 MPa,700oC SCW 190 for 10 min;(A)PS;(B)PE;(C)PC here.PC,polycarbonate;PE,polyethylene;SEM,scanning electron microscope. Figure 3.115 The results of the fourier transform infrared spectrum of feedstocks and the 191 products here. Figure 4.1 Effect of reaction temperature on UF plastics gasification:(A)CE/HE;(B)202 gas fraction(C2Hx,x=4,6)(time 10 min;pressure 23 MPa;feedstock mass fraction 5 wt.%)here.UF,urea-formaldehyde. Figure 4.2 Effect of reaction time on UF plastics gasification:(A)CE/HE;(B)gas 203 fraction(C2Hx,x=4,6)(temperature 700oC;pressure 23 MPa;feedstock mass fraction 5 wt.%).UF,urea-formaldehyde. Figure 4.3 Effect of feedstock mass fraction on UF plastics gasification:(A)CE/HE;204 (B)gas fraction(C2Hx,x=4,6)(temperature 700oC;time 10 min; pressure 23 MPa).UF,urea-formaldehyde. Figure 4.4 Effect of reaction pressure on UF plastics gasification:(A)CE/HE;(B)gas 205 fraction(C2Hx,x=4,6)(temperature 700oC;time 10 min;feedstock mass fraction 5 wt.%).UF,urea-formaldehyde. Figure 4.5 CE and HE of UF and PS at every temperature(time 10 min;pressure 205 23 MPa;feedstock mass fraction 5 wt.%).PS,polystyrene;UF,urea-formaldehyde. Figure 4.6 Products in quartz tube:(A)UF;(B)PS(temperature 700oC;time 10 min;206 pressure 23 MPa;feedstock mass fraction 5 wt.%).PS,polystyrene;UF,urea-formaldehyde. Figure 4.7 Residual solid products under electron microscope:(A)UF;(B)PS 206 (temperature 700oC;time 10 min;pressure 23 MPa;feedstock mass fraction 5 wt.%;magnification 1000).PS,polystyrene;UF,urea-formaldehyde. Figure 4.8 Gasification efficiency of UF plastics gasification(pressure,23 MPa;208 feedstock mass fraction,5 wt.%).UF,urea-formaldehyde. Figure 4.9 Third-order plot for UF plastics gasification(pressure,23 MPa;feedstock 209 mass fraction,5 wt.%).UF,urea-formaldehyde. Figure 4.10 Influence of the temperature on gasification of the discarded circuit boards 211 (A)CE,HE,and gas production;and(B)mole fraction(time 20 min;feedstock concentration 5 wt.%). Figure 4.11 Infrared chemical bond analysis of the gasification of solid products at 212 different temperatures(time,20 min;pressure,23 MPa;feedstock concentration 5 wt.%). Figure 4.12(A)XRF spectroscopy element content analysis of the solid products from 213 the gasification reaction;and(B)bromide ion concentration in the liquid product at different temperatures(time 20 min;feedstock
concentration 5 wt.%).XRF,X-ray fluorescence. Figure 4.13 XRD pattern of(A)the experimental materials;and(B)the gasified solid 213 product(temperature 400oC;time 20 min;pressure 23 MPa;feedstock concentration 5 wt.%).XRD,X-ray diffractometry. Figure 4.14 Substances present in the liquid products at different temperatures(time,214 20 min;pressure,23 MPa;feedstock concentration 5 wt.%). Figure 4.15 SEM analysis of the solid products at different temperatures(A)raw 215 materials;(B)400oC;(C)500oC;(D)500oC;(E)600oC;and(F)700oC(time,20 min;pressure,23 MPa;feedstock concentration 5 wt.%).SEM,scanning
electron microscopy. Figure 4.16 Influence of residence time on gasification of the discarded circuit boards:216 (A)CE and HE;(B)gas production;(C)mole fraction;and(D)abundance(temperature 700oC;feedstock concentration 5 wt.%). Figure 4.17 Infrared chemical bond analysis of solid gasification products at different 217 residence times(temperature 700oC;feedstock concentration 5 wt.%). Figure 4.18(A)XRF element content analysis of the solid product of gasification;and 218 (B)bromide ion concentration in the liquid products at different residence times(temperature 700oC;feedstock concentration 5 wt.
%).XRF,X-ray fluorescence. Figure 4.19 XRD patterns of a gasified solid product after(A)10 min,and(B)20 min 218 (temperature 700oC;feedstock concentration 5 wt.%).XRD,X-ray diffractometry. Figure 4.20 SEM analysis of the solid products at different reaction times(A)1 min;(B)219 5 min;(C)10 min;and(D)20 min(temperature 700oC;feedstock concentration 5 wt.%).SEM,scanning electron microscopy. Figure 4.21 Influence of the feedstock concentration on the gasification of discarded 220 circuit boards gasification:(A)CE,HE,and gas production;and(B)molar fraction(temperature 650oC;time 5 min). Figure 4.22 Effect of feedstock concentration on the gasification of discarded circuit 221 boards:CE/HE(temperature 700oC;time 10 min;feedstock concentration 5 wt.%). Figure 4.23 Infrared chemical bond analysis of the solid products of gasification with 221 additives(time,10 min;feedstock concentration 5 wt.%). Figure 4.24 XRD pattern of the gasification solid product(A)without the additive;and 222 (B)with the additive(temperature 700oC;time 10 min;feedstock concentration 5 wt.%).XRD,X-ray diffractometry.
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