The myth of hazardous-to-wealth concept: transformation of marine microplastics to pyrolysis gas

Figures & data

Table 1. Physiochemical properties of marine microplastic wastes.

Samples	Collection method	Types of microplastics	Chemical compositions	Size (μm)	Moisture content (wt.%)	Ultimate analysis (%)^a	Tmax degradation (°C)^b
1	Plankton nets-Hand	Fibers, Microbeads, Film	PE, PET, PU, PS	5–100	0.1 ≤ M ≤ 0.2	C = 93.20 H = 1.68 N = 0.22 S = 0.05 O* = 4.85	351.2
2	Plankton nets-Hand	Fibers, Fragments	PP, PET, PVC	200–300	0.1 ≤ M ≤ 0.2	C = 83.20 H = 6.20 N = 0.06 S = 0.20 O = 10.04	355.5
3	Plankton nets-Hand	Fibers, Fragments, Film, and Microbeads	PE, PLA, PU, PP, PC, PS	80–5000	0.2 ≤ M	C = 84.70 H = 7.85 N = 1.02 S = 0.35 O = 6.08	375.2
4	Plankton nets-Hand	Fibers, Fragments, Film, and Microbeads	PE, PET, PVC, PP, PS, PU	60–7000	0.5 ≤ M	C = 79.91 H = 12.22 N = 0.14 S = 0.82 O = 7.45	368.5
Average	–	–	–	5–7000	0.25	C = 85.25 H = 6.99 N = 0.36 S = 0.36 O = 7.04	361.28

^aThe oxygen value is calculated based on a 100-sum of (C+H+N+S).

^bThe maximum temperature of the degradation of the plastic is based on the active phase (Stage II) shown in the DTG profile.

Figure 1. (a) TGA and (b) DTG profile of 4 microplastic samples.

Figure 2. Gaseous product distribution from various microplastic samples.

Table 2. Yield, selectivity, and conversion of the microplastic to different products.

Sample	Conversion to gas (%)	Conversion to solid (%)	Selectivity (vol%)						Yield (%)
			H2	CO	CO2	CH4	C2+	Syngas	H2	CO	CO2	CH4	C2+	Syngas
1	89.1	10.9	21.2	19.6	46.3	3.7	9.2	40.8	18.9	17.5	41.3	3.3	8.2	36.4
2	81.3	18.7	17.1	22.5	39.3	9.1	12.0	39.6	13.9	18.3	32.0	7.4	9.8	32.2
3	79.5	20.5	14.2	30.0	37.2	4.3	14.3	44.2	11.3	23.9	29.6	3.4	11.4	35.2
4	72.1	27.9	26.3	22.2	32.2	7.1	12.2	48.5	19.0	16.0	23.2	5.1	8.8	35.0

*The total conversion = solid + gaseous products.

Figure 3. Morphology change of sample 3 (a) before and (b) after degradation in an inert pyrolyzed condition.