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Materials and Technologies for Waste Recovery and Treatment

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (20 August 2023) | Viewed by 8422

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Special Issue Editors

Dr. Biao Fu

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Guest Editor

State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
Interests: coal geology and geochemistry; fly ash petrology and chemistry; heavy-metal control from solid fuel combustion; critical metal recovery from coal-related materials; clean coal utilization

Dr. Yukun Huang

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Guest Editor

ZhongYuan Critical Metals Laboratory, Zhengzhou University, Zhengzhou 450001, China
Interests: critical metals; separation; recovery of cobalt; Ionic liquid extraction

Dr. Yuan Liu

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Guest Editor

Department of Pediatrics, New York University Grossman School of Medicine, New York, NY 10016, USA
Interests: waste recovery and treatment; heavy metals; emerging contaminants

Special Issue Information

Dear Colleagues,

Modern industry and civil activities produce huge amounts of waste globally. The disposal of waste to minimize waste amount/toxicity and the discovery of new ways to recycle energy and produce critical materials from waste are critical to establishing a green and sustainable society. Waste material is complicated due to its variety of forms (solid, liquid and gas) and components depending on the sources and disposal methods used. Due to the heterogeneity and complexity of different waste materials, the recovery or conversion of high-value products or energy from waste faces major challenges. Low-cost and environmentally friendly recovery and treatment routes require designing innovative reagents and technologies.

To this end, this Special Issue aims to provide a platform for scientists and technicians worldwide to share new ideas, methods and technologies involving the recovery of critical/high-value materials and energy from waste generated from numerous industrial and civil activities. Original research and review articles are welcome. Topics of interest include, but are not limited to: mining waste, coal washing and combustion/gasification byproducts; metal smelting slag or dust; biomass waste; municipal solid waste; and related advances, including:

Novel methods for and advances in characterizing the chemistry and structure of target materials in waste;
Novel concepts and methods for the conversion of waste into high-value products;
New reagents, technologies or apparatus for critical material extraction and separation from waste;
Environmental impacts of toxic substances in waste and environmental issues arising from the treatment of waste materials.

Dr. Biao Fu
Dr. Yukun Huang
Dr. Yuan Liu
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. Applied Sciences 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

advanced analytical techniques for waste
critical material extraction
novel separation reagents
conversion methods for waste-to-valued-products
environmental geochemistry of toxics in waste
environmental assessment

Published Papers (5 papers)

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Research

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9 pages, 893 KiB

Open AccessCommunication

Feasible Applicability of Deep Learning for Solid Detection in Concrete Wastewater: An Evaluation

by Yongfang Chen and Qingyu Yao

Appl. Sci. 2023, 13(15), 8652; https://doi.org/10.3390/app13158652 - 27 Jul 2023

Viewed by 534

Abstract

Concrete wastewater from mixing stations leads to environment contamination due to its high alkalinity. The wastewater can be reused if its solid content is accurately and timely detected. However, investigations into the traditional methods for wastewater reuse have demonstrated that they are time consuming and not efficient. Therefore, the exact acquirement of solid content in concrete wastewater becomes a necessity. Recent studies have shown that deep learning has been successfully applied to detect the concentration of chemical solutions and the particle content of suspending liquid. Moreover, deep learning can also be used to recognize the accurate water level, which facilitates the detection of the solid–liquid separation surface after wastewater sedimentation. Therefore, in this article the feasibility and challenges of applying deep learning to detect the solid content of concrete wastewater were comprehensively evaluated and discussed. Finally, an experimental setup was proposed for future research, and it indicated that transfer learning, data augmentation, hybrid approaches, and multi-sensor integration techniques can be selected to facilitate future experimental performances. Full article

(This article belongs to the Special Issue Materials and Technologies for Waste Recovery and Treatment)

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11 pages, 1563 KiB

Open AccessArticle

Analysis of the Delamination Process with Nitric Acid in Multilayer Composite Food Packaging

by Agnė Šleiniūtė, Gintaras Denafas and Tamari Mumladze

Appl. Sci. 2023, 13(9), 5669; https://doi.org/10.3390/app13095669 - 4 May 2023

Cited by 3 | Viewed by 1536

Abstract

Multilayer packaging, commonly referred to as composite materials, is widely utilized in food storage, distribution, and consumption. The employment of plastic packaging, which consists of multiple layers of polymers, ink, paper, and metal, has elicited concerns regarding its detrimental impact on the environment. This article presents an in-depth study of the delamination process of multilayer plastic waste (MLPW) recycling, which is deemed as an effective solution for MLPW recycling. This study aimed to examine the effects of temperature, concentration, width, and ultrasound on the separation of layers in multilayer packaging. The results demonstrated that ultrasound is the most influential factor with nitric acid concentration ranking as the second most significant factor. The findings also disclosed considerable disparities among the time frames, and the impacts of various factors, such as temperature and concentration, lay the groundwork for further investigation into this process. The study underscores the importance of temperature and nitric acid concentration, which can inform the design of future experiments and the development of more efficient methods for layer separation. Full article

(This article belongs to the Special Issue Materials and Technologies for Waste Recovery and Treatment)

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15 pages, 7594 KiB

Open AccessArticle

Recycled Carbon Fibers with Improved Physical Properties Recovered from CFRP by Nitric Acid

by Asuka Sakai, Winarto Kurniawan and Masatoshi Kubouchi

Appl. Sci. 2023, 13(6), 3957; https://doi.org/10.3390/app13063957 - 20 Mar 2023

Cited by 5 | Viewed by 1685

Abstract

To effectively reuse a large amount of Carbon Fiber Reinforced Plastics (CFRP) waste, the carbon fibers should be able to be recovered without degrading their quality. In this report, we developed a new approach to recover carbon fibers from CFRPs with improved physical properties compared to virgin carbon fibers with an environmentally friendly recycling method using nitric acid. Following the decomposition of the CFRP waste in nitric acid at 80 °C, both recycled carbon fibers and decomposed resin were recovered. The obtained recycled carbon fibers showed 1.4 times higher tensile strength and 2.2 times higher interfacial shear strength to resin compared to virgin carbon fibers. TEM-EDX analysis showed a decrease in the abundance of voids existing in the carbon fiber surface layer and new polar functional groups caused by nitric acid existing inside the voids, leading to increased tensile strength. Furthermore, XPS analysis showed that the interfacial shear strength improved due to the formation of new polar functional groups due to nitric acid. The possibility of applying recycled carbon fibers to CFRP products was shown by elucidating the mechanism that expressed its physical properties during the recycling process, leading to a novel approach to realizing closed-loop recycling. Full article

(This article belongs to the Special Issue Materials and Technologies for Waste Recovery and Treatment)

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16 pages, 4432 KiB

Open AccessArticle

One-Step Microcrystalline Glass Preparation Using Smelting Slag from Waste Automobile Three-Way Catalysts through Iron Collection

by Xiaoping Zhu, Yingda Huo, Ruiming Zhao, Hao Wu, Fubao Li, Shuchen Sun and Chuan Liu

Appl. Sci. 2022, 12(22), 11723; https://doi.org/10.3390/app122211723 - 18 Nov 2022

Cited by 2 | Viewed by 1570

Abstract

The smelting slag obtained through iron collection from waste automobile three-way catalysts was used as a raw material to prepare microcrystalline glass through a one-step crystallization heat treatment. The phase composition and microstructure of the prepared glass were analyzed through X-ray diffraction and scanning electron microscopy–energy dispersive X-ray spectroscopy, respectively. Single-factor experiments were conducted to investigate the effects of crystallization temperature from 900 to 950 °C and crystallization time from 0.5 to 4 h on the physical and chemical properties of the microcrystalline glass. The results indicated that the optimum crystallization temperature and time for preparing microcrystalline glass with glass smelting slag through the proposed one-step crystallization heat treatment process were 950 °C and 3 h, respectively. Under these experimental conditions, the number of crystalline phases of the microcrystalline glass was high, the grains were mainly spherical and columnar particles, the sample structure was dense, and the best results were obtained: the density was 2.72 g/cm³, the water absorption was 1.55%, the porosity was 4.2%, the Vickers hardness was 618 HV, the acid resistance was 2.6%, and the alkali resistance was 0.04%. In addition, the results of the toxicity characteristic leaching procedure indicated that the leaching concentrations of heavy metals such as Zn, Cr, and Pb in the microcrystalline glass were lower than those in the base glass and were considerably lower than the acceptable limits. The microcrystalline glass obtained from final smelting slag through heat treatment can enhance the stabilization of harmful elements. The findings of this study can be applied to the treatment of bulk solid waste. Full article

(This article belongs to the Special Issue Materials and Technologies for Waste Recovery and Treatment)

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Review

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33 pages, 3245 KiB

Open AccessReview

Nitrate-Polluted Waterbodies Remediation: Global Insights into Treatments for Compliance

by José A. Fernández-López, Mercedes Alacid, José M. Obón, Ricardo Martínez-Vives and José M. Angosto

Appl. Sci. 2023, 13(7), 4154; https://doi.org/10.3390/app13074154 - 24 Mar 2023

Cited by 4 | Viewed by 2389

Abstract

Nitrate (NO₃⁻) pollution of surface and groundwater bodies is a global problem of increasing concern, which has stimulated significant research interest. Nitrogen is crucial for life as a macronutrient for living organisms on Earth, but the global nitrogen cycle has been seriously altered by intensification of human activities, leading to eutrophication and hypoxic conditions of aquatic ecosystems. Due to nitrogen overfertilization, intensive agricultural practices generate huge nitrate fluxes that inadvertently deteriorate water quality. Different industrial processes also contribute to NO₃⁻ pollution in the environment. There are multiple technologies capable of achieving effective denitrification of waterbodies to ensure safe NO₃⁻ levels. Either separation-based or transformation-based denitrification technologies must address the challenges of by-product generation, increased energy demand, and reduced environmental footprint. This paper highlights the most used approaches, along with some promising alternatives for remediation of nitrate-polluted waters. Full article

(This article belongs to the Special Issue Materials and Technologies for Waste Recovery and Treatment)

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