H2 Production from Real Wastes of Polyethylene Terephthalate and Polylactic Acid using CNx/Ni2P Nanocatalyst

Abstract

In this study, H2(g) production from real wastes of polyethylene terephthalate and polylactic acid using CNx/Ni2P nanocatalyst was investigated with photoreforming process. Optimum experimental conditions were found at ultrasonicated 4.8 mg/ml CNx/Ni2P nanocatalyst, at pre-treated 20 mg/ml polyethylene terephthalate, at pre-treated 20 mg/ml polylactic acid, at 4 ml aqueous 1 M KOH, at 10 ml internal volume of sealed photoreactor under anaerobic conditions, at 1200 W Xe solar lamp, at 60 h photoreforming solar irradiation time, at AM 1.0G, at 150 mW/cm2, at 25°C, respectively. XRD, FESEM, EDX, FTIR, TEM, DRS and XPS analyzes were performed for characterization studies of microplastics. Polyethylene terephthalate and polylactic acid measurements were measured in inductively coupled plasma mass spectrometry (ICP-MS). H2(g) measurements were made in gas chromatography–mass spectrometry (GC-MS). The maximum 41.40 ± 5.10 and 48.60 ± 3.12 µmol H2 / gsub yields were measured for CNx=20 mg/ml and for Ni2P=20 mg/ml, respectively. The maximum 18.26 ± 1.18 and 52.41 ± 7.29 µmol H2 / gsub H2(g) production yields were found for non-sonicated CNx/Ni2P and ultra-sonicated CNx/Ni2P nanocatalyst, respectively, after 24 h photoreforming solar irradition time. The maximum 123.75 ± 11.92 and 267.41 ± 24.65 µmol H2 / gsub H2(g) production yield was measured for polyethylene terephthalate and polylactic acid, respectively, after 60 h photoreforming solar irradiation time. The maximum 6.57 ± 0.87Percentage and 2.43 ± 0.38Percentage stoichiometric H2 conversion yields were observed for polyethylene terephthalate and polylactic acid, respectively, after 60 h photoreforming solar irradition time. The maximum 96 and 57 μmol H2 / gsub H2(g) yields for polyethylene terephthalate were obtained over CNx/Ni2P and H2NCNx/Ni2P, respectively, after 60 h photoreforming solar irradiation time. The maximum 182 and 173 μmol H2 / gsub H2(g) yields for polylactic acid were observed over CNx/Ni2P and H2NCNx/Ni2P, respectively, after 60 h photoreforming solar irradiation time. The maximum 4.85 ± 0.62, 88.37 ± 10.74, 26.55 ± 1.95, 21.94 ± 1.86, 75.30 ± 9.34, 60.07 ± 5.11 and 14.61 ± 2.14 μmol H2 / gsub H2(g) production yields were obtained for Acetate, Ethylene glycol, Formate, Glycolate, Glyoxal, Lactate and Terephthalate oxidation intermediates, respectively, after 24 h photoreforming solar irradiation times. 126 nmol Acetate, 131 nmol Formate, 5 nmol Glycolate and 6200 nmol Glyoxal organic oxidation intermediates for polyethylene terephthalate with CNx/Ni2P nanocatalyst were found after 7 days photoreforming solar irradiation time. 67 nmol Acetate and 63 nmol Formate organic oxidation intermediates for polylactic acid with CNx/Ni2P nanocatalyst were obtained after 7 days photoreforming solar irradiation time. Photoreforming process is a very effective, easy to apply, economical and environmentally friendly method for the removal of plastic and microplastic wastes.