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17. Recovering Valuable Chemicals from Polypropylene Waste via a Mild Catalyst-Free Hydrothermal Process

Author

Xu, Qiongying, Wang, Qiandi, Yang, Jiaqi, Liu, Wenzong, and Wang, Aijie

Abstract

Waste polypropylene (PP) presents a significant environmental challenge, owing to its refractory nature and inert C–C backbone. In this study, we introduce a practical chemical recovery strategy from PP waste using a mild catalyst-free hydrothermal treatment (HT). The treatment converts 64.1% of the processed PP into dissolved organic products within 2 h in an air atmosphere at 160 °C. Higher temperatures increase the PP conversion efficiency. Distinct electron absorption and emission characteristics of the products are identified by spectral analysis. Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) reveals the oxidative cracking of PP into shorter-chain homologues (10–50 carbon atoms) containing carboxylic and carbonyl groups. Density functional theory (DFT) calculations support a reaction pathway involving thermal C–H oxidation at the tertiary carbon sites in the polymer chain. The addition of 1% H2O2further enhances the oxidation reaction to produce valuable short-chain acetic acids, enabling gram-scale recycling of both pure PP and disposable surgical masks from the real world. Techno-economic analysis (TEA) and environmental life cycle costing (E-LCC) analysis suggest that this hydrothermal oxidation recovery technology is financially viable, which shows significant potential in tackling the ongoing plastic pollution crisis and advancing plastic treatment methodologies toward a circular economy paradigm.

Published
2024
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24. Preparation of graphene/polymer composite photocathode for QDSSC

Author

Feng Gu, Meng Cao, Wang Qiandi, Tan Shen, Kai Xu, Yue Shen, Linjun Wang, and Jie Tan

Subjects
Conductive polymer, Materials science, Graphene, Scanning electron microscope, Nanotechnology, Photocathode, law.invention, symbols.namesake, chemistry.chemical_compound, Polyvinyl butyral, chemistry, Ethyl cellulose, Chemical engineering, law, Solar cell, symbols, Raman spectroscopy
Abstract

Graphene (rGO) was fabricated by modified Hummers method and a reducing process. Conductive polymer/graphene films were obtained by scalpel technology and used as photocathode in CdS quantum dot-sensitized solar cell (QDSSC). Polymers used in this paper were ethyl cellulose (EC), polyphenyl vinyl (PPV) and polyvinyl butyral (PVB), respectively. The obtained composite films were investigated by X-ray diffraction, Raman spectroscopy technology and scanning electron microscope (SEM). The photoelectric properties of QDSSCs were tested under AM 1.5 irradiation. Test results show that the film performance of the EC/rGO and PPV/rGO photocathode have been improved effectively. Power conversion efficiency (PCE) of the relative QDSSCs under AM 1.5 irradiation were 0.81% and 0.86%, respectively.

Published
2013
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25. Preparation and properties of low-cost graphene counter electrodes for dye-sensitized solar cells

Author

Yue Shen, Feng Gu, Qishuang Wu, Wang Qiandi, Meng Cao, and Linjun Wang

Subjects
Auxiliary electrode, Materials science, Graphene, Scanning electron microscope, Energy conversion efficiency, Analytical chemistry, law.invention, Dielectric spectroscopy, symbols.namesake, Dye-sensitized solar cell, Chemical engineering, law, Electrode, symbols, Raman spectroscopy
Abstract

With the advantages of excellent electrical properties, high catalytic activity and low-cost preparation, Graphene is one of the most expected carbon materials to replace the expensive Pt as counter electrodes for dye-sensitized solar cells (DSSCs). In this paper, graphe ne counter electrodes were obtained by simple doctor-blade coating method on fluorine tin oxides (FTOs). The samples were investigated by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). Then the low-cost graphene electrodes were applied in typical sandwich-type DSSCs with TiO 2 or ZnO as photoanodes, and their photo electric conversion efficiency ( ) were about 4.34% and 2.28%, respectively, which were a little lower than those of Pt electrodes but much higher than those of graphite electrodes. This law was consistent with the test results of electrochemical impedance spectroscopy (EIS). Low- cost graphene electrodes can be applied in DSSCs by process optimization. Keywords : graphene, counter electrode, DSSC

Published
2013
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30. Carbon source recovery from waste sludge reduces greenhouse gas emissions in a pilot-scale industrial wastewater treatment plant.

Author

Wang Q, Li X, Liu W, Zhai S, Xu Q, Huan C, Nie S, Ouyang Q, Wang H, and Wang A

Abstract

Carbon cycle regulation and greenhouse gas (GHG) emission abatement within wastewater treatment plants (WWTPs) can theoretically improve sustainability. Currently, however, large amounts of external carbon sources used for deep nitrogen removal and waste sludge disposal aggravate the carbon footprint of most WWTPs. In this pilot-scale study, considerable carbon was preliminarily recovered from primary sludge (PS) through short-term (five days) acidogenic fermentation and subsequently utilized on-site for denitrification in a wool processing industrial WWTP. The recovered sludge-derived carbon sources were excellent electron donors that could be used as additional carbon supplements for commercial glucose to enhance denitrification. Additionally, improvements in carbon and nitrogen flow further contributed to GHG emission abatement. Overall, a 9.1% reduction in sludge volatile solids was achieved from carbon recovery, which offset 57.4% of external carbon sources, and the indirect GHG emissions of the target industrial WWTP were reduced by 8.05%. This study demonstrates that optimizing the allocation of carbon mass flow within a WWTP has numerous benefits., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors.)

Published
2022
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