Article
Chemistry, Multidisciplinary
Anting Ding, Ming Li, Chuanying Liu, Xingwang Zhang, Lecheng Lei, Chengliang Xiao
Summary: An alternative method for recovering precious metals from spent catalysts using salt aqua regia is reported. The salt aqua regia solution, made of purely inorganic salts, can completely dissolve palladium and gold. It exhibits good solubility and electrochemical stability, making it a promising candidate for precious metals recovery.
CELL REPORTS PHYSICAL SCIENCE
(2022)
Review
Chemistry, Physical
Yao Chen, Qianyu Qiao, Jiazhen Cao, Hexing Li, Zhenfeng Bian
Summary: As non-renewable resources, the demand for precious metals (PMs) is increasing, leading to a growing focus on the recovery of secondary resources. However, the chemical stability of PMs makes recovery conditions harsher and poses serious safety concerns. This article discusses research progress on PM recovery strategies, challenges, and future prospects.
Article
Agronomy
Valeria Ancona, Ida Rascio, Giorgia Aimola, Claudia Campanale, Paola Grenni, Martina Di Lenola, Gian Luigi Garbini, Vito Felice Uricchio, Anna Barra Caracciolo
Summary: The study demonstrates the effectiveness of using a Monviso clone of poplar trees to promote the degradation of PCBs and heavy metals in a historically contaminated soil in Southern Italy. After 900 days, PCBs and most heavy metals were found to be decreased below legal limits, along with an increase in organic carbon content and microbial abundance. The results suggest that poplar-based bioremediation technology can be a successful nature-based solution for soil quality improvement and contaminant removal.
Article
Engineering, Environmental
Taiyu Huang, Jie Zhu, Xiongfei Huang, Jujun Ruan, Zhenming Xu
Summary: This study investigates the distribution of precious metals in waste printed circuit boards and evaluates the economic value of recycling. Gold, silver, and palladium were detected in different parts of the boards, with gold being widely distributed and silver concentrated on the pins of electronic components. The economic value of recyclable precious metals in 1 ton of waste printed circuit boards reaches up to $2292.94, with gold contributing the most. This study highlights the economic benefits and provides guidance for the recovery of precious metals from waste printed circuit boards.
Article
Engineering, Environmental
Huan Li, Elsayed Oraby, Jacques Eksteen
Summary: The research shows that using cyanide-starved glycine solution can effectively extract precious metals from waste printed circuit boards, reducing cyanide usage significantly while maintaining good selectivity and allowing reagent recycling. Under optimized conditions, 90.1% Au, 89.4% Ag, and 70.1% Pd were extracted, along with 81.0% Cu and 15.0% Zn.
Article
Engineering, Chemical
Huan Li, Elsayed Oraby, Jacques Eksteen
Summary: This study provides a greener approach to extract precious metals from waste printed circuit boards using alkaline glycine solution in the presence of an oxidant. Two oxidants, potassium permanganate and potassium ferricyanide, were compared in alkaline media. The results showed that decreasing particle size and increasing oxidant concentration significantly enhanced gold extraction.
MINERALS ENGINEERING
(2022)
Article
Engineering, Environmental
Zhen Qin, Hongxia Deng, Ruihua Huang, Shanshan Tong
Summary: Research has shown that MXene hybrid aerogels exhibit high selectivity and capture capacity, particularly for Au(III) and Ag(I). Through mechanisms such as oxidation-reduction and electrostatic attraction, MXGA can effectively trap noble metals such as gold and silver, and demonstrate excellent performance even in low temperature environments.
CHEMICAL ENGINEERING JOURNAL
(2022)
Review
Environmental Sciences
Yingbo Dong, Nuo Mingtana, Jinyu Zan, Hai Lin
Summary: This review focuses on bioleaching as an environmentally friendly method for extracting precious metals from waste printed circuit boards (WPCBs). The paper provides an overview of the current status of bioleaching for precious metals from WPCBs, describes the underlying mechanisms, and outlines the influence of various process factors on leaching efficiency. The review underscores the considerable potential of bioleaching in WPCBs applications, but also describes the limitations and current enhanced processes for improving leaching efficiency.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2023)
Article
Engineering, Environmental
Sidi Deng, Zhongqing Xiao, Wencai Zhang, Aaron Noble, Subodh Das, Yuehwern Yih, John W. Sutherland
Summary: This study proposes and evaluates a novel process called gas-assisted microflow extraction (GAME) for efficiently recovering precious metals from waste printed circuit boards (WPCBs). An economic analysis is conducted to verify the feasibility of the GAME-based process at an industrial scale, and cost-effective production strategies are further investigated. This study may establish a paradigm for economically-informed decisions in sustainable technologies.
RESOURCES CONSERVATION AND RECYCLING
(2023)
Article
Materials Science, Multidisciplinary
Aleksandar M. Mitrasinovic, Yang Yuankun, Srecko Stopic, Milinko Radosavljevic, Petros E. Tsakiridis
Summary: One of the major challenges in metal extraction is the generation of large amounts of slag, which often contains harmful elements. This study used gravity separation and gravity settling to recover valuable and potentially harmful elements from mining waste. After treatment, a significant portion of these elements gathered in a newly formed matte, and the remaining slag could be considered a beneficial source of copper and other materials.
Article
Engineering, Environmental
Zhe Wang, Yudong Liu, Long Meng, Jingkui Qu, Zhancheng Guo
Summary: A resource-saving process of synergistic smelting to extract precious metals from spent automotive catalysts (SACs) and waste printed circuit boards (WPCBs) was proposed. Metal components in WPCBs were used as the collector metal of precious metals, while carrier components in SACs were used as the slag formative. Under optimal conditions, including a SiO2-FeO-Al2O3-MgO-CaO slag system, the extraction efficiencies of Pd, Rh, Ag, and Au were 90.5%, 93.2%, 98.9%, and 94.5%, respectively. The novel process provides an effective way for extracting precious metals from secondary resources.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2023)
Article
Green & Sustainable Science & Technology
Mohammad Reza Bilesan, Irina Makarova, Bjorn Wickman, Eveliina Repo
Summary: A novel physical separation method, including multiple steps such as sieving, hydrocyclone, and dilution-gravity method, was proposed to effectively recover precious metals from waste printed circuit boards. Through experiments and analysis, it was demonstrated that the method achieved efficient recovery of gold, palladium, silver, and copper.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Multidisciplinary Sciences
Johann H. Martinez, Sergi Romero, Jose J. Ramasco, Ernesto Estrada
Summary: The study investigates the international waste trade network from 2001 to 2019, identifying countries at risk of improper waste handling. Chemical tracers are utilized to determine the environmental impact of waste in these countries. The research reveals that most hazardous waste is traded among developed nations, but there is a disproportionate asymmetry in the flow from developed to developing countries. By using a dynamic model, the study simulates the propagation of waste stress through the network and its impact on countries. It identifies 28 countries with a low Environmental Performance Index that are at high risk of waste congestion and improper handling of hazardous waste. Evidence of pollution caused by heavy metals, volatile organic compounds, and persistent organic pollutants is found in several of these countries due to improper waste handling.
NATURE COMMUNICATIONS
(2022)
Article
Mathematics
Gil Cohen
Summary: This research is the first attempt to create machine learning algorithmic systems for automatic trading of precious metals. The study uses three forecast methodologies and analyzes five precious metals. The research found negative autocorrelation between daily returns and identified lagged interdependencies among the metals. Moreover, the system shows better accuracy in forecasting price-up trends.
Article
Green & Sustainable Science & Technology
Yao Chen, Mengjiao Xu, Jieya Wen, Yu Wan, Qingfei Zhao, Xia Cao, Yong Ding, Zhong Lin Wang, Hexing Li, Zhenfeng Bian
Summary: This article presents a greener photocatalytic process for recovering up to seven precious metals from waste, demonstrating its potential for wide application and importance in implementing a circular economy.
NATURE SUSTAINABILITY
(2021)
Article
Engineering, Environmental
Xiaojian Liu, Bei Wang, Yayun Ma, Xiangyang Zhou, Juan Yang, Yuehui He, Jingjing Tang, Fanyun Su, Wan Yang
Summary: This study proposes a combined process of reduction roasting of herb-medicine residue and oxalic acid leaching to improve the recovery efficiency of lithium from spent lithium-ion batteries. By utilizing the reducing gas produced from the pyrolysis of herb-medicine residue, the layered structure of the cathode powder is destroyed and converted into Li2CO3, Ni, Co, and MnO. Additionally, selective extraction of lithium is achieved using oxalic acid, and the efficiency and kinetics of lithium extraction are improved under the combined action of herb-medicine residue and oxalic acid.
Article
Engineering, Environmental
Muxina Konarova, Nuno Batalha, Gabriel Fraga, Mohamed H. M. Ahmed, Steven Pratt, Bronwyn Laycock
Summary: This study presents a proof of concept for a technology that integrates PET recovery from mixed plastic waste and plastic pyrolysis. By depolymerizing PET into TPA using a low volatility oil as medium, it achieves low-pressure operation and a selective separation and recovery of TPA from the product mix. Full PET conversion and high TPA recovery were achieved, making it an effective solution for processing mixed waste streams and improving the yield and quality of liquid product from thermal pyrolysis compared to untreated feedstock.
Article
Engineering, Environmental
Zhenhua Sun, Jing Li, Xuejiang Wang, Siqing Xia, Jianfu Zhao
Summary: This study investigated the influence of in-situ formed MgFe2O4 on the hydrothermal treatment of swine manure. The results showed that the in-situ formation of MgFe2O4 improved the dehydration and decarboxylation of organic components in swine manure, thereby improving its carbonization degree. Furthermore, it enhanced the stabilization of heavy metals and the retention of phosphorus. MgFe2O4 modified hydrochars exhibited remarkable adsorption capacity for Pb(II) and Cu(II) without any leaching of heavy metals.
Article
Engineering, Environmental
Yijing Jiang, Boyang Leng, Jingxin Xi
Summary: The increased generation of municipal solid waste has had a significant impact on the economy, environment, and public health. The current waste treatment process has limitations. By developing a comprehensive social costing model, this study assesses the impacts of municipal solid waste management throughout its life cycle and provides policymakers with best practices and feasibility information.
Article
Engineering, Environmental
Marina Hernandes de Paula e Silva, Ricardo Coser Mergulha, Jose Geraldo Vidal Vieira, Andrea Brasco Pampanelli, Rodrigo Salvador, Diogo Aparecido Lopes Silva
Summary: This study developed and implemented a self-assessment tool to assist companies in decision-making processes for establishing circular flows based on Lean Manufacturing and Circular Economy principles. The tool utilized a maturity model and was applied to nine companies of varying characteristics. The findings revealed that certain companies showed higher maturity in water-waste and chemical-emissions management, with larger enterprises focusing on these strategies. However, many companies lacked sufficient training and employee awareness prior to seeking cleaner alternatives, and comprehensive actions to manage the product lifecycle were lacking. To address these gaps, the tool provided tailored recommendations for each company to improve their processes, products, and value chain.
Article
Engineering, Environmental
Gamze Dogdu, Turgay Pekdemir, Sanaz Lakestani, Seyda Karabork, Osman Cavus
Summary: This paper presents data on food waste associated with mini size food packaging services, highlighting the difficulties in emptying the food and consumer wastefulness as the main causes. These findings have significant implications for the sustainability of food and relevant packaging.
Article
Engineering, Environmental
Qingxia Li, Xin Kong, Yuxin Chen, Jianan Niu, Jia Jing, Jin Yuan, Yifeng Zhang
Summary: This study investigates how to enhance methane production from food waste after hydrothermal pretreatment. The results demonstrate a significant increase in methane yield when zero-valent iron and magnetite are used together, and high organic loading is favorable for methane production. Microbial diversity analysis further reveals the dominant pathways and metabolic processes involved in methane generation.
Article
Engineering, Environmental
D. H. H. Sim, I. A. W. Tan, L. L. P. Lim, E. T. Lau, B. H. Hameed
Summary: The development of controlled-release fertilizer formulation is important for preventing environmental pollution caused by nutrient leaching and volatilization. This study combined biochar-based fertilizer with encapsulation technology to improve the nutrient release mechanism. Optimal conditions for synthesizing urea-impregnated biochar (UIB) were determined using central composite design, and the release of nitrogen was described by mathematical models. Results showed that encapsulated UIB (EUIB) achieved complete release of nitrogen in water and exhibited improved water retention in sandy-textural soil. Therefore, EUIB derived from peppercorn waste has the potential to be used as a sustainable controlled-release fertilizer for agriculture.
Article
Engineering, Environmental
Yuchuan Wang, Neslihan Akdeniz
Summary: Incorporating biochar into composting systems can increase compost temperatures. This study developed a heat transfer model for a biochar-amended co-composting system and found that biochar increased thermal conductive losses but also enhanced microbial activity, resulting in an overall increase in total heat unit. When biochar was applied on the surface, it mainly functioned as an insulator.
Article
Engineering, Environmental
George Tsalis, Birger Boutrup Jensen, Jessica Aschemann-Witzel
Summary: This paper empirically explores the relationship between retail price promotions and household food waste. The results show that households with a higher proportion of discount food purchases and environmental awareness tend to waste less food, while larger households and those lacking food handling skills tend to waste more food.
Article
Engineering, Environmental
Lukas Friederici, Arne Koch, Patrick Martens, Jana Pantzke, Sebastiano Di Bucchianico, Thorsten Streibel, Christopher P. Rueger, Ralf Zimmermann
Summary: The increasing demand for lightweight materials has led to a rise in fiber-reinforced plastic (FRP) production. However, the properties and compositional range of FRPs pose challenges to recycling strategies. Pyrolysis has emerged as a promising method for separating the fibers from the polymer matrix. This study investigated the pyrolysis process using thermal analysis and high-resolution mass spectrometry, and also assessed the toxicity of the recovered fibers using an in vitro model.
Review
Engineering, Environmental
Devika Kannan, Shakiba Khademolqorani, Nassibeh Janatyan, Somaieh Alavi
Summary: This paper introduces Smart Waste Management (SWM) that applies Industry 4.0 technologies in waste management. A framework called SWM4.0 is developed, which highlights the importance of smart people, smart cities, smart enterprises, and smart factories in achieving successful waste management. The paper also suggests future research directions and managerial implications.