Exploring the potential of
resource-recovery from plastic
waste in New-Zealand
Elsa Dhombres1 , Oseweuba Valentine Okoro2 , Zhifa Sun2∗
1EPF
Graduate school of Engineering
2Department of Physics, Otago University ,
*Email address: zhifa.sun@otago.ac.nz; Phone: 64 3 479 7812
1
Contents
• Activities undertaken in the last weeks
• Results obtained
• Conclusion
2
Activities undertaken in the
last weeks
3
Characterisation of the HTL-oil via elemental
analysis.
Estimating the molecular formula of the HTL-oil.
Estimation of the mass of CO2 produced by burning
1kg of plastic as justification for the un-favourability
of incineration as a waste management strategy.
Higher Heating Value (HHV) estimation of the HTLoil.
Identification of major chemical species present in the
oil via Gas Chromatograph–Mass Spectrometry (GCMS) and Nuclear Magnetic Resonance (NMR).
4
Results obtained
5
Characterisation of the HTL oil via
elemental analysis:
Exp. run C
H
N
S
O
wt. % wt. % wt. % wt. % wt.%
Initial
82.60 13.64 Trace Trace 3.76
Second
83.48 14.09 Trace Trace 2.43
The mean mass percentage of oxygen, carbon,
hydrogen, is therefore determined to be 3.1 wt. %,
83.04 wt.% and 13.9 wt. % respectively.
6
Molecular formula estimation of the
HTL-oil
• Molecular formula of the HTL-oil :
𝐶𝐻2 37𝑛 𝑂
• The feedstock was 𝐶𝐻2
1261𝑛 𝑂
+ 𝐴𝑠ℎ
 The HTL-oil is ash free.
 The mean carbon and hydrogen content of HTL-oil of
83.04 wt. % and 13.9 wt. % is similar to the mean carbon
and hydrogen content of fossil crude of 84 wt % and 14
wt. %
7
Estimation of the mass of CO2
produced from plastic incineration
Mass of CO2 produced by burning plastic:
𝑦
[𝐶𝑥 𝐻𝑦 ]𝑛 + 𝑛 𝑥 +
× 𝑂2 + 3.76𝑁2 + 𝐴𝑠ℎ
4
𝑛𝑦
𝑦
→ 𝑛𝑥𝐶𝑂2 +
𝐻2 𝑂 + 𝑛 𝑥 + 3.76 × 𝑁2 + 𝐴𝑠ℎ
2
4
Considering that the molar mass of CH2 and CO2 are
14g/mol and 44g/mol respectively, burning 1kg of plastic
would produce 3.1 kg of CO2, therefore based on the
estimated mass of waste plastic generated per year (275
million metric tons) an additional 852.5 million tons of
CO2 will be introduced to the atmosphere annually.
8
HHV estimation of the HTL-oil
The HHV of the HTL-oil was estimated using the equation:
𝐻𝐻𝑉𝐻𝑇𝐿−𝑜𝑖𝑙
%𝑂
= 0.338 %C + 1.28 %H −
+ 0.095 %𝑆
8
= 47.90 ± 0.41 MJ/kg
 The HHV of the HTL–oil is higher than the HHV of the
plastics and similar to the HHV of fossil crude of 47 MJ/kg.
9
NMR analysis
 The protons detected via
NMR are largely from
compounds with alkyl
and alkene functional
groups.
100
GC-MS analysis
 The main compound was found
to be largely long chain alkanes
representing about a mole
fraction of 0.75 of the HTL-oil
mixture.
Name: Heptacosane
Formula: 𝐶27 𝐻56
 These n-alkanes can be recovered
via High-performance liquid
chromatography separation.
91
100
O
O
50
55
100
69
83
O
O
108
55
207
125 147
179
282
0
50
100
150
200
250
300
350
(mainlib) 9-Octadecenoic acid (Z)-, phenylmethyl ester
50
81
67
99
111
141
167
198 226
268
0
50
100
150
200
250
(mainlib) 7-Methyl-Z-tetradecen-1-ol acetate
300
350
111