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EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Environmental Sustainability and Applications".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 12913

Special Issue Editors


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Guest Editor
Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei 10608, Taiwan
Interests: resources recovery; mineral processing; hydrometallurgy; urban mining; recycling policy and management

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Guest Editor
Institute of mineral resources engineering, National Taipei University of Technology, Taipei 10608, Taiwan
Interests: heopolymer technology; mineral processing; waste recycling and reutilization; solidification/stabilization hazardous materials
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Guest Editor
Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei, Taiwan
Interests: waste to energy and resources; synthesis and application of nanoporous materials; synthesis and characterization of catalysts; valorization of plastic waste; fluidized bed technology
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
Interests: mineral carbonation; carbon capture and utilization; hydrometallurgy; metal recycling; waste recycling and management; environmental chemistry

Special Issue Information

Dear Colleagues,

The 16th Earth Symposium (EARTH 2022) is the premier international congress in the field of resources and material circulation. The main objective is to foster knowledge transfer and exchange of experience amongst delegates with academic and industrial backgrounds.

We will offer all participants knowledge of the latest advances in resources processing, hydrometallurgy, pyrometallurgy, organic–inorganic material processing, waste to energy, recycling policy and management, net zero CO2 emissions, and other important topics related to the environment, waste to energy, and resources and materials recycling.

Focus: This Special Issue focuses on introducing recycling policy and management, waste treatment, waste management, and CO2 reduction throughout East Asia (Korea, Japan, Taiwan, China, and Thailand).

Scope: Due to the limited resources and increase in CO2 concentration in the atmosphere, there are growing pressures and challenges for human beings. To address these problems, waste treatment, recycling and reutilization and reduction of CO are necessary now to obtain the optimal options for future generations.

Purpose: This Special Issue aims to introduce the new trends in waste treatment, recycling and reutilization, recycling policy and management, and CO2 reduction.

Dr. Li-Pang Wang
Dr. Wei-Hao Lee
Dr. Ren Xuan Yang
Dr. Hsing Jung Ho
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • recycling policy and management
  • waste treatment and management
  • waste recycling and reutilization
  • green technology
  • CO2 reduction technology
  • policy for net zero CO2 emissions

Published Papers (8 papers)

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21 pages, 3489 KiB  
Article
Separation and Recovery of Copper and Nickel in the Leachate of a Waste IC Lead Frame through Synergistic Solvent Extraction Using a Binary Extractant Containing LIX984N and Cyanex302 Followed by Selective Stripping
by Li-Pang Wang, Jia-Yan Lin, Yan-Jhang Chen, Bu-Ching Tseng, Ching-Hsiang Hsu, Mingyin Kou, Heng Zhou and Paiboon Sreearunothai
Sustainability 2024, 16(1), 77; https://doi.org/10.3390/su16010077 - 21 Dec 2023
Viewed by 777
Abstract
The IC lead frame is an essential component in semiconductor packaging, primarily composed of a nickel (Ni)–copper (Cu) alloy in which Ni is electroplated onto a Cu substrate. In this study, synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302, followed [...] Read more.
The IC lead frame is an essential component in semiconductor packaging, primarily composed of a nickel (Ni)–copper (Cu) alloy in which Ni is electroplated onto a Cu substrate. In this study, synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302, followed by two-stage selective stripping using sulfuric acid (H2SO4) and nitric acid (HNO3) as the stripping agent, was employed to separate and recover Cu and Ni from the leachate of an IC lead frame. The results indicated that under the optimal conditions of synergistic solvent extraction with an extraction pH value of 1, an extractant concentration of 0.015 M LIX984N + 0.0375 M Cyanex302, an extraction aqueous/organic (A/O) ratio of 1:1, and an extraction time of 5 min, the extraction efficiencies for Cu and Ni were 99.8% and 1.17%, respectively. The distribution ratios were DCu 999 and DNi 0.012, resulting in a separation factor of 83,250. In addition, the separation factor was much higher than that of using individual extractant of LIX984N (6208.3) or Cyanex302 (22,185.2). Subsequently, under optimal first-stage stripping conditions, using 0.05 M H2SO4 at a stripping organic/aqueous (O/A) ratio of 1:1, and with a stripping time of 3 min, a stripping efficiency of 99.9% for Ni was achieved. Next, under optimal second-stage stripping conditions, using 5 M HNO3 at a stripping O/A ratio of 2:1, and with a striping time of 3 min, a stripping efficiency of 99.9% for Cu was achieved. Finally, sodium hydroxide (NaOH) was added to the respective stripping solutions to precipitate Ni and Cu ions, followed by calcination treatment for the precipitates to obtain NiO and CuO, respectively. The purity of the former was 99.74% and that of the latter was 99.82%. The results demonstrate that synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302 can almost entirely extract Cu in the leachate of an IC lead frame at a lower extraction pH and a lower extractant concentration, thus reducing the co-extraction of Ni. In addition, less co-extracted Ni in the organic phase can be selectively stripped using dilute H2SO4, thus reducing the co-stripping of Cu. Hence, the effective separation and recovery of Cu and Ni in IC lead frame leachate can be achieved, which contributes to improving the sustainability of natural resources. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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19 pages, 6380 KiB  
Article
A Novel Procedure for Comprehensive Recovery of Zinc Fluoride, Manganese Fluorides, Manganese Dioxide, and Carbon Powder from the Electrode Powder of Spent Alkaline Batteries
by Li-Pang Wang, Wei-Tai Hsu, Yan-Jhang Chen, Yan-Fu Chen, I-Chun Lin, Heng Zhou, Mingyin Kou and Paiboon Sreearunothaia
Sustainability 2023, 15(17), 13216; https://doi.org/10.3390/su151713216 - 03 Sep 2023
Viewed by 954
Abstract
In this paper, a novel procedure is proposed for comprehensively recovering zinc fluoride (ZnF2), manganese fluorides [MnFx(x = 2, 3)], manganese dioxide (MnO2), and carbon powder from the electrode powder of spent alkaline batteries. Firstly, hydrofluoric acid [...] Read more.
In this paper, a novel procedure is proposed for comprehensively recovering zinc fluoride (ZnF2), manganese fluorides [MnFx(x = 2, 3)], manganese dioxide (MnO2), and carbon powder from the electrode powder of spent alkaline batteries. Firstly, hydrofluoric acid (HF) leaching is conducted on the electrode powder of spent alkaline batteries. Secondly, potassium permanganate (KMnO4) is introduced into the leachate to selectively precipitate manganese (Mn) ions to recover MnO2. Subsequently, the water content in the leachate is evaporated to recover ZnF2. Finally, the leaching residue is leached again by using HF, after which the water content in the leachate is evaporated to recover MnFx. The results indicated that under optimal conditions of a HF concentration of 4 M, a leaching time of 15 min, and a liquid–solid ratio of 5 mL/g, the optimal leaching selectivity for Zn and Mn was achieved and the leaching efficiencies of Zn and Mn were 97.83% and 39.94%, respectively. When KMnO4 with a dosage (KMnO4/Mn ion molar ratio) of 0.5:1 was added to the leachate, MnO2 with a grade of 91.68% and a Mn recovery of 39.07% was obtained. In addition, ZnF2 with a grade of 97.98% and a Zn recovery of 96.15% was also obtained after removing the water content from the leachate via evaporation. Under the optimal conditions of a HF concentration of 2 M, a leaching time of 15 min, and a liquid–solid ratio of 10 mL/g for the leaching residue, followed by removing the water content in the leachate via evaporation, MnFx with a grade of 94.20% and a Mn recovery of 59.46%, was obtained. The residue of the releaching process was carbon powder. The effectiveness of the proposed recovery procedure was confirmed. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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12 pages, 494 KiB  
Article
Effects of Basicity Index on Incinerator Fly Ash Melting Process and Stabilization
by Wei-Sheng Chen, Gregory Chen and Cheng-Han Lee
Sustainability 2023, 15(15), 11610; https://doi.org/10.3390/su151511610 - 27 Jul 2023
Viewed by 739
Abstract
The generation of hazardous industrial waste in Taiwan has rapidly increased, reaching 1.5 million tons produced annually in 2021. Most of this waste was burned in incinerators, with about 15% (225,000 tons) of it converted into fly ash. Incinerator fly ash primarily consists [...] Read more.
The generation of hazardous industrial waste in Taiwan has rapidly increased, reaching 1.5 million tons produced annually in 2021. Most of this waste was burned in incinerators, with about 15% (225,000 tons) of it converted into fly ash. Incinerator fly ash primarily consists of heavy metals, dioxins, chlorides, and silica. Historically, fly ash disposal has only relied on cement solidification, contributing to insufficient landfill capacity and soil-pollution concerns. To address these issues, the melting process has been a feasible solution, wherein the heavy metals can be encapsulated within a vitrified structure to prevent them from leaching out. However, the melting point of fly ash is too high, so this study aimed to explore the optimal basicity index for fly ash to conduct the melting process. Basicity indices are estimated by the ratio of CaO/SiO2, and the melting point of the fly ash can be decreased during the melting process with the right basicity index. In this study, the characteristics of incinerator fly ashes from industrial waste and laboratory waste were initially investigated. With their basicity indices adjusted with two sources of silica, the fly ashes were tested at 1100~1400 °C to observe whether they melted. The vitrified slags were subsequently subjected to TCLP, XRF, and ICP tests to verify their stability. In summary, we discovered that fly ash could be melted through the melting process with the basicity index adjusted to under 1.28, with the silica source as either glass or silica sand powder. After melting, the heavy metals were confirmed to be stabilized in the vitrified slags. Consequently, the melting process could be an alternative solution for fly ash disposal that is sustainable and eco-friendly. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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12 pages, 4085 KiB  
Article
Stabilization of Waste Mercury with Sulfide through the Ball-Mill Method and Heat Treatment
by Wei-Sheng Chen, Chien-Ching Chi and Cheng-Han Lee
Sustainability 2023, 15(13), 10333; https://doi.org/10.3390/su151310333 - 29 Jun 2023
Viewed by 1002
Abstract
Most mercury supplies nowadays are limited due to their toxicity and difficulty in treatment. If mercury is stored inappropriately, it will not only contaminate the environment but also pass along the food chain and eventually to humans. Therefore, addressing mercury waste is crucial [...] Read more.
Most mercury supplies nowadays are limited due to their toxicity and difficulty in treatment. If mercury is stored inappropriately, it will not only contaminate the environment but also pass along the food chain and eventually to humans. Therefore, addressing mercury waste is crucial for the environment and human health. This study aims to stabilize waste mercury using sulfur powder and generate mercury production through a ball mill and heat treatment. To begin with, sulfur powder, waste mercury (98%) from chemicals, and milling balls will be mixed in this step. The parameters in this process were milling temperature, milling time, ball/material ratio, and milling speed. Under the optimal parameters of 35 °C for milling temperature, 12 h for milling time, 46% for the ball/material ratio, and 300 rpm for milling speed, β-HgS was obtained, and α-HgS was subsequently acquired through dry distillation in a tubular furnace at 600 °C for 3 h. On the other hand, high-purity mercury (99.5%) could be recovered under the circumstances of heating α-HgS with oxygen at 600 °C for 3 h. In a nutshell, waste mercury (98%) could be treated appropriately under the state of α-HgS, and high-purity mercury (99.5%) could be produced and reused for other industries through this research. Both contribute to environmental remediation and resource recovery goals. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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15 pages, 2726 KiB  
Article
Fires in Waste Treatment Facilities: Challenges and Solutions from a Fire Investigation Perspective
by Wen-Yen Juan, Chia-Lung Wu, Fan-Wei Liu and Wei-Sheng Chen
Sustainability 2023, 15(12), 9756; https://doi.org/10.3390/su15129756 - 19 Jun 2023
Cited by 2 | Viewed by 1612
Abstract
Fires in waste treatment facilities have significant social, economic, and environmental implications. Factors such as self-heating of lithium-ion batteries, thermal runaway, friction, human activities, technical errors, and unfavorable storage conditions contribute to these fires. High-risk categories include illegal dumping sites, recycle collection stations, [...] Read more.
Fires in waste treatment facilities have significant social, economic, and environmental implications. Factors such as self-heating of lithium-ion batteries, thermal runaway, friction, human activities, technical errors, and unfavorable storage conditions contribute to these fires. High-risk categories include illegal dumping sites, recycle collection stations, and wood-related facilities. The frequency of fires in waste treatment facilities and the emergence of new waste types have led to public discontent. Regulatory challenges and oversight difficulties pose further obstacles. This study analyzes fire incidents in Kaohsiung City’s waste treatment facilities over the past five years, exploring their causes, regulatory frameworks, and practical challenges. Valuable insights and recommendations are provided to enhance fire safety and risk assessment. These measures aim to mitigate fires’ environmental and facility consequences and their impact. Prioritizing fire prevention and reducing potential economic, social, and environmental consequences are crucial for improving fire safety in waste treatment facilities. Addressing these challenges and prioritizing the safety and sustainability of the waste treatment industry is imperative. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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16 pages, 11583 KiB  
Article
Effects of Tb-Doped BiVO4 on Degradation of Methylene Blue
by Wei-Sheng Chen, Ming-Hong Wu and Jun-Yi Wu
Sustainability 2023, 15(8), 6994; https://doi.org/10.3390/su15086994 - 21 Apr 2023
Cited by 1 | Viewed by 1516
Abstract
Bismuth vanadate (BiVO4) is a narrow-bandgap semiconductor (~2.41 Ev) that responds to visible light. The efficiency of degradation of organic dyes is indexed by methylene blue (MB). After 150 min, the efficiency of MB degradation by pure BiVO4 was about [...] Read more.
Bismuth vanadate (BiVO4) is a narrow-bandgap semiconductor (~2.41 Ev) that responds to visible light. The efficiency of degradation of organic dyes is indexed by methylene blue (MB). After 150 min, the efficiency of MB degradation by pure BiVO4 was about 20%. Its adsorption performance and electron–hole pair migration ability are weak, and the photocatalytic activity of pure BiVO4 needs to be improved. BiVO4 doped with rare earth ions can facilitate the separation of photogenerated electron–hole pairs, thereby enhancing photocatalytic activity in the visible light range. This study investigates changes in the structure and morphology of BiVO4 doped with different atomic percentages of terbium (Tb). BiVO4 powders were prepared by the hydrothermal method with different atomic percentages of Tb (at% = 0, 1, 3, and 5). Doping Tb benefits the coexistence of monoclinic/tetragonal heterostructures, which changes the band gap and improves degradation efficiency. After 150 min of visible light irradiation, the photocatalyst doped with 3 atomic percent of Tb exhibited 98.2% degradation of methylene blue. The degradation percentage of MB remained stable in the presence of 3at%Tb-doped BiVO4 composite. The optimal parameters for the amount of photocatalyst added were studied. Real-field simulations of metal ions and inorganic salts both retain high levels of degradation efficiency. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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12 pages, 2653 KiB  
Article
Electrochemical Properties and the Adsorption of Lithium Ions in the Brine of Lithium-Ion Sieves Prepared from Spent Lithium Iron Phosphate Batteries
by Hsing-I Hsiang and Wei-Yu Chen
Sustainability 2022, 14(23), 16235; https://doi.org/10.3390/su142316235 - 05 Dec 2022
Cited by 2 | Viewed by 1920
Abstract
Because used LiFePO4 batteries contain no precious metals, converting the lithium iron phosphate cathode into recycled materials (Li2CO3, Fe, P) provides no economic benefits. Thus, few researchers are willing to recycle them. As a result, environmental sustainability can [...] Read more.
Because used LiFePO4 batteries contain no precious metals, converting the lithium iron phosphate cathode into recycled materials (Li2CO3, Fe, P) provides no economic benefits. Thus, few researchers are willing to recycle them. As a result, environmental sustainability can be achieved if the cathode material of spent lithium-iron phosphate batteries can be directly reused via electrochemical technology. Lithium iron phosphate films were developed in this study through electrophoretic deposition using spent lithium-iron phosphate cathodes as raw materials to serve as lithium-ion sieves. The lithium iron phosphate films were then coated with a layer of polypyrrole (PPy) conductive polymer to improve the electrochemical properties and the lithium-ion adsorption capacity for brine. Cyclic voltammetry, charge/discharge testing, and an AC impedance test were used to determine the electrochemical properties and lithium-ion adsorption capacity of lithium-ion sieves. The findings indicate that lithium iron phosphate films prepared from spent LiFePO4 cathodes have a high potential as a lithium-ion sieve for electro-sorption from brine. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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11 pages, 584 KiB  
Commentary
Perspectives on Taiwan’s Pathway to Net-Zero Emissions
by Pin-Han Chen, Cheng-Han Lee, Jun-Yi Wu and Wei-Sheng Chen
Sustainability 2023, 15(6), 5587; https://doi.org/10.3390/su15065587 - 22 Mar 2023
Cited by 5 | Viewed by 3435
Abstract
For achieving net-zero emissions by 2050, countries worldwide are committed to setting ambitious carbon reduction targets. In 2022, the officially published report, “Taiwan’s Pathway to Net-Zero Emissions in 2050”, sets out a comprehensive transition plan based on four fundamental strategies: energy, industrial, lifestyle, [...] Read more.
For achieving net-zero emissions by 2050, countries worldwide are committed to setting ambitious carbon reduction targets. In 2022, the officially published report, “Taiwan’s Pathway to Net-Zero Emissions in 2050”, sets out a comprehensive transition plan based on four fundamental strategies: energy, industrial, lifestyle, and social. This transition will likely entail an infrastructure transformation in all sectors of the economy, embracing renewable energy, electricity, and low-carbon fuels. While the Taiwan government is rolling up its sleeves to accelerate the pace of carbon-emission reduction, it is risky to set targets without considering the full implications of net-zero emission and how it will be achieved. This paper provides four insights into Taiwan’s net-zero-emission plan from a perspective of the current understanding of decarbonization and the techniques urgently needed. Although many uncertainties and outstanding questions exist in our net-zero energy systems, and the required granular information for decision makers to track progress has not been clearly identified, this paper points out the characteristics that have been neglected and provides guidance for all stakeholders—governments, businesses, investors, and citizens—to work together on a coordinated plan to tackle climate change. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Waste Treatment and CO2 Reduction)
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