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21 pages, 3489 KiB

Open AccessArticle

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

Cited by 1 | Viewed by 1366

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 D_Cu 999 and D_Ni 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

Open AccessArticle

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 - 3 Sep 2023

Viewed by 1504

Abstract

In this paper, a novel procedure is proposed for comprehensively recovering zinc fluoride (ZnF₂), manganese fluorides [MnF_{x(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 [MnF_{x(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 MnF_x. 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, MnF_x 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

Open AccessArticle

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

Cited by 1 | Viewed by 1227

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

Open AccessArticle

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

Cited by 2 | Viewed by 1543

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

Open AccessArticle

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 5 | Viewed by 2740

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

Open AccessArticle

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 2 | Viewed by 2049

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

Open AccessArticle

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 - 5 Dec 2022

Cited by 2 | Viewed by 2603

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

Open AccessCommentary

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 7 | Viewed by 5139

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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