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Veksha A, Wang Y, Foo JW, Naruse I, Lisak G. Defossilization and decarbonization of hydrogen production using plastic waste: Temperature and feedstock effects during thermolysis stage. JOURNAL OF HAZARDOUS MATERIALS 2023; 452:131270. [PMID: 36989781 DOI: 10.1016/j.jhazmat.2023.131270] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/16/2023] [Accepted: 03/21/2023] [Indexed: 06/19/2023]
Abstract
The replacement of natural gas with plastic-derived pyrolysis gas can defossilize H2 production, while subsequent capture, utilization and storage of carbon in a solid form can decarbonize the process. The objective of this study was to investigate H2 production from three types of plastics using a process comprising pyrolysis (600 °C) and thermolysis stages (1200-1500 °C). Depending on the plastic feedstock and thermolysis temperature, the laboratory-scale setup generated 1000-1350 mL/min product gas with H2 purity of 74.3-94.2 vol%. The recovery of 5-9 wt% molecular H2 per mass of plastics was achieved. Other products included solid residue (0.1-12 wt%) and oil (8-52 wt%) from the pyrolysis reactor, solid carbon (36-53 wt%) and gas impurities (2-16 wt%) from the thermolysis reactor. The purity of H2 gas was detrimentally influenced by polyethylene terephthalate in the feedstock due to the dilution of gas by CO. The decomposition of methane containing in the pyrolysis gas was the limiting reaction step during H2 production and improved at higher thermolysis temperature. Three solid carbon structures were formed during the thermolysis stage regardless of the plastic type: carbon black aggregates, carbon black aggregates coated with a layer of pyrolytic carbon and a carbon film on the inner reactor wall. Among the three types of carbon, the highest valorization potential was identified for carbon black aggregates. Plastic feedstock composition had little if any effect on carbon black properties, while high thermolysis temperature (1500 °C) reduced the particle sizes and increased the surface area of aggregates.
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Affiliation(s)
- Andrei Veksha
- Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore.
| | - Yuxin Wang
- Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore; Department of Mechanical Systems Engineering, Nagoya University, Tokai National Higher Education and Research, 464-8603, Japan
| | - Jun Wei Foo
- Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore
| | - Ichiro Naruse
- Institute of Materials and Systems for Sustainability, Nagoya University, Tokai National Higher Education and Research, 464-8601, Japan
| | - Grzegorz Lisak
- Residues and Resource Reclamation Centre (R3C), Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.
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Zhao X, Boruah B, Chin KF, Đokić M, Modak JM, Soo HS. Upcycling to Sustainably Reuse Plastics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2100843. [PMID: 34240472 DOI: 10.1002/adma.202100843] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/23/2021] [Indexed: 06/13/2023]
Abstract
Plastics are now indispensable in daily lives. However, the pollution from plastics is also increasingly becoming a serious environmental issue. Recent years have seen more sustainable approaches and technologies, commonly known as upcycling, to transform plastics into value-added materials and chemical feedstocks. In this review, the latest research on upcycling is presented, with a greater focus on the use of renewable energy as well as the more selective methods to repurpose synthetic polymers. First, thermal upcycling approaches are briefly introduced, including the redeployment of plastics for construction uses, 3D printing precursors, and lightweight materials. Then, some of the latest novel strategies to deconstruct condensation polymers to monomers for repolymerization or introduce vulnerable linkers to make the plastics more degradable are discussed. Subsequently, the review will explore the breakthroughs in plastics upcycling by heterogeneous and homogeneous photocatalysis, as well as electrocatalysis, which transform plastics into more versatile fine chemicals and materials while simultaneously mitigating global climate change. In addition, some of the biotechnological advances in the discovery and engineering of microbes that can decompose plastics are also presented. Finally, the current challenges and outlook for future plastics upcycling are discussed to stimulate global cooperation in this field.
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Affiliation(s)
- Xin Zhao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Bhanupriya Boruah
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Department of Chemical Engineering, Indian Institute of Science, CV Raman Avenue, Bangalore, Karnataka, 560012, India
| | - Kek Foo Chin
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Miloš Đokić
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Jayant M Modak
- Department of Chemical Engineering, Indian Institute of Science, CV Raman Avenue, Bangalore, Karnataka, 560012, India
| | - Han Sen Soo
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Artificial Photosynthesis (Solar Fuels) Laboratory, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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Lisak G. Reliable environmental trace heavy metal analysis with potentiometric ion sensors - reality or a distant dream. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 289:117882. [PMID: 34364114 DOI: 10.1016/j.envpol.2021.117882] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/13/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Over two decades have passed since polymeric membrane ion-selective electrodes were found to exhibit sufficiently lower detection limits. This in turn brought a great promise to measure trace level concentrations of heavy metals using potentiometric ion sensors at environmental conditions. Despite great efforts, trace analysis of heavy metals using ion-selective electrodes at environmental conditions is still not commercially available. This work will predominantly concentrate on summarizing and evaluating prospects of using potentiometric ion sensors in view of environmental determination of heavy metals in on-site and on-line analysis modes. Challenges associated with development of reliable potentiometric sensors to be operational in environmental conditions will be discussed and reasoning behind unsuccessful efforts to develop potentiometric on-site and on-line environmental ion sensors will be explored. In short, it is now clear that solely lowering the detection limit of the ion-selective electrodes does not guarantee development of successful sensors that would meet the requirement of environmental matrices over long term usage. More pressing challenges of the properties and the performance of the potentiometric sensors must be addressed first before considering extending their sensitivity to low analyte concentrations. These are, in order of importance, selectivity of the ion-selective membrane to main ion followed by the membrane resistance to parallel processes, such as water ingress to the ISM, light sensitivity, change in temperature, presence of gasses in solution and pH and finally resistance of the ion-selective membrane to fouling. In the future, targeted on-site and on-line environmental sensors should be developed, addressing specific environmental conditions. Thus, ion-selective electrodes should be developed with the intention to be suitable to the operational environmental conditions, rather than looking at universal sensor design validated in the idealized and simple sample matrices.
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Affiliation(s)
- Grzegorz Lisak
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore, 637141, Singapore.
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Yaqoob T, Rani M, Mahmood A, Shafique R, Khan S, Janjua NK, Shah AA, Ahmad A, Al-Kahtani AA. MXene/Ag 2CrO 4 Nanocomposite as Supercapacitors Electrode. MATERIALS 2021; 14:ma14206008. [PMID: 34683600 PMCID: PMC8540627 DOI: 10.3390/ma14206008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 01/13/2023]
Abstract
MXene/Ag2CrO4 nanocomposite was synthesized effectively by means of superficial low-cost co-precipitation technique in order to inspect its capacitive storage potential for supercapacitors. MXene was etched from MAX powder and Ag2CrO4 spinel was synthesized by an easy sol-gel scheme. X-Ray diffraction (XRD) revealed an addition in inter-planar spacing from 4.7 Å to 6.2 Å while Ag2CrO4 nanoparticles diffused in form of clusters over MXene layers that had been explored by scanning electron microscopy (SEM). Energy dispersive X-Ray (EDX) demonstrated the elemental analysis. Raman spectroscopy opens the gap between bonding structure of as-synthesized nanocomposite. From photoluminence (PL) spectra the energy band gap value 3.86 eV was estimated. Electrode properties were characterized by applying electrochemical observations such as cyclic voltammetry along with electrochemical impedance spectroscopy (EIS) for understanding redox mechanism and electron transfer rate constant Kapp. Additionally, this novel work will be an assessment to analyze the capacitive behavior of electrode in different electrolytes such as in acidic of 0.1 M H2SO4 has specific capacitance Csp = 525 F/g at 10 mVs−1 and much low value in basic of 1 M KOH electrolyte. This paper reflects the novel synthesis and applications of MXene/Ag2CrO4 nanocomposite electrode fabrication in energy storage devices such as supercapacitors.
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Affiliation(s)
- Tahira Yaqoob
- Department of Physics, The Women University Multan, Multan 66000, Pakistan; (T.Y.); (R.S.)
| | - Malika Rani
- Department of Physics, The Women University Multan, Multan 66000, Pakistan; (T.Y.); (R.S.)
- Correspondence:
| | - Arshad Mahmood
- National Institute of Lasers and Optronics (NILOP), College PIEAS, NILORE, Islamabad 45650, Pakistan;
| | - Rubia Shafique
- Department of Physics, The Women University Multan, Multan 66000, Pakistan; (T.Y.); (R.S.)
| | - Safia Khan
- Department of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan; (S.K.); (N.K.J.)
| | - Naveed Kausar Janjua
- Department of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan; (S.K.); (N.K.J.)
| | - Aqeel Ahmad Shah
- Department of Metallurgical Engineering, NED University of Engineering and Technology, Karachi 75270, Pakistan;
| | - Awais Ahmad
- Departamento de Quimica Organica, Universidad de Cordoba, Edificio Marie Curie (C-3), Ctra Nnal IV-A, Km 396, E14014 Cordoba, Spain;
| | - Abdullah A. Al-Kahtani
- Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia;
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Pyrolysis for Nylon 6 Monomer Recovery from Teabag Waste. Polymers (Basel) 2020; 12:polym12112695. [PMID: 33207591 PMCID: PMC7697768 DOI: 10.3390/polym12112695] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/12/2020] [Accepted: 11/12/2020] [Indexed: 11/16/2022] Open
Abstract
In this work, we used pyrolysis to treat teabag waste (TBW). Changes in the pyrolysis temperature affected the composition and yield of the products. For example, more non-condensable gases and less char were produced with an increase in the pyrolysis temperature. Pyrolysis conducted under a nitrogen environment yielded caprolactam at temperatures between 400 and 700 °C. An increase in the pyrolysis temperature from 400 to 500 °C increased the caprolactam yield from 3.1 to 6.2 wt.%. At 700 °C, the yield decreased to 4.6 wt.%. The highest caprolactam yield (i.e., 6.2 wt.% at 500 °C) was equivalent to 59.2 wt.% on the basis of the weight of the non-biomass part of the TBW. The pyrolytic products other than caprolactam (e.g., combustible gases, pyrolytic liquid, and char) can function as fuels to supply energy during pyrolysis in order to increase and maintain the temperature. The higher heating values (HHVs) of the combustible gases and pyrolytic liquid produced at 500 °C were 7.7 and 8.3 MJ kg-1, respectively. The HHV of the char produced at 500 °C was 23 MJ kg-1, which is comparable to the HHV of coal. This work will help to develop effective pyrolysis processes to valorize everyday waste by recovering value-added chemicals such as polymer monomers and by producing alternative fuels.
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Niuniavaite D, Baltakys K, Dambrauskas T, Eisinas A, Rubinaite D, Jaskunas A. Microstructure, Thermal Stability, and Catalytic Activity of Compounds Formed in CaO-SiO 2-Cr(NO 3) 3-H 2O System. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1299. [PMID: 32630781 PMCID: PMC7407582 DOI: 10.3390/nano10071299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/19/2020] [Accepted: 06/29/2020] [Indexed: 11/30/2022]
Abstract
In this work, the thermal stability, microstructure, and catalytic activity in oxidation reactions of calcium silicate hydrates formed in the CaO-SiO2-Cr(NO3)3-H2O system under hydrothermal conditions were examined in detail. Dry primary mixture with a molar ratio of CaO/SiO2 = 1.5 was mixed with Cr(NO3)3 solution (c = 10 g Cr3+/dm3) to reach a solution/solid ratio of the suspension of 10.0:1. Hydrothermal synthesis was carried out in unstirred suspensions at 175 °C for 16 h. It was determined that, after treatment, semicrystalline calcium silicate hydrates C-S-H(I) and/or C-S-H(II) with incorporated Cr3+ ions (100 mg/g) were formed. The results of in situ X-ray diffraction and simultaneous thermal analyses showed that the products were stable until 500 °C, while, at higher temperatures, they recrystallized to calcium chromate (CaCrO4, 550 °C) and wollastonite (800-850 °C). It was determined that both the surface area and the shape of the dominant pore changed during calcination. Propanol oxidation experiments showed that synthetic semicrystalline calcium silicate hydrates with intercalated chromium ions are able to exchange oxygen during the heterogeneous oxidation process. The obtained results were confirmed by XRD, STA, FT-IR, TEM, SEM, and BET methods, and by propanol oxidation experiments.
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Affiliation(s)
- Domante Niuniavaite
- Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania; (D.N.); (T.D.); (A.E.); (D.R.)
| | - Kestutis Baltakys
- Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania; (D.N.); (T.D.); (A.E.); (D.R.)
| | - Tadas Dambrauskas
- Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania; (D.N.); (T.D.); (A.E.); (D.R.)
| | - Anatolijus Eisinas
- Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania; (D.N.); (T.D.); (A.E.); (D.R.)
| | - Dovile Rubinaite
- Department of Silicate Technology, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania; (D.N.); (T.D.); (A.E.); (D.R.)
| | - Andrius Jaskunas
- Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu 19, LT-50270 Kaunas, Lithuania;
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Wu Y, Ge L, Veksha A, Lisak G. Cobalt and nitrogen co-doped porous carbon/carbon nanotube hybrids anchored with nickel nanoparticles as high-performance electrocatalysts for oxygen reduction reactions. NANOSCALE 2020; 12:13028-13033. [PMID: 32537620 DOI: 10.1039/d0nr02773a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Non-precious metal-nitrogen-carbon (MNC) materials have been recognized as alternatives to noble-metal catalysts, such as Au/C, Pt/C and Ru/C. As the precursors of MNC catalysts, carbonized zeolite imidazole frameworks (ZIFs) have been widely studied due to their porosity and the composition of ligands, including carbon and nitrogen. Herein, we successfully synthesize a non-precious metal-based ORR catalyst with nickel nanoparticles anchored on cobalt and nitrogen co-doped porous carbon/carbon nanotubes (Ni/Co-NC), employing ZIF-67 metal-organic frameworks as precursors. The Ni/Co-NC catalyst shows an excellent onset potential of 0.984 V and a half-wave potential of 0.869 V in 0.1 M KOH, comparable to those of commercial Pt/C. The excellent ORR performance of Ni/Co-NC was attributed to the synergistic coexistence of the atomically dispersed metal species coordinated with nitrogen (metal-N sites) and carbon-encapsulated nickel nanoparticles as well as the hierarchical porous structure in the catalyst. In addition, the Ni/Co-NC catalyst possesses outstanding anti-poisoning capacity and long-term duration against methanol crossover in an alkaline environment. The obtained results enable the Ni/Co-NC catalyst to explore potential applications in energy conversion and storage systems.
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Affiliation(s)
- Yan Wu
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Clean Tech One, Singapore 637141, Singapore.
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