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This study investigates the influence of super-fast heating rate and holding time on the microstructure and mechanical properties of dual-phase (DP) Fe-0.16C-1.4Mn sheet steel. Super-fast heating and cooling rates were achieved via induction heating and gas quenching. The results were also compared with those for a conventional low-speed heat treatment. The microstructures were characterized in detail using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and electron probe microanalysis. The results showed that the layered structure of the DP Fe-0.16C-1.4Mn steel after super-fast heating was mainly composed of recrystallized ferrite, martensite clusters, and a small amount of residual austenite. Compared with the conventional method, super-fast heating significantly refined the grains and improved yield and tensile strength, but it slightly reduced the elongation. The fraction of martensite, which depends on the nucleation and growth behavior of austenite, was significantly affected by the heating rate and holding time. The DP structure of Fe-0.16C-1.4Mn steel had an atypical layered heterogeneous structure, with an uneven plastic strain between the two phases occurring during the deformation process, which is something that can improve fracture elongation.

Municipal solid waste incineration (MSWI) fly ash is a hazardous waste containing heavy metals. Secondary aluminum dross (SAD) is a hazardous waste discharged from aluminum smelting, containing active aluminum nitride (AlN). In this work, heavy metals from MSWI fly ash were reduced into alloy by AlN from SAD, and the slag was manufactured into transparent glass for building. Reduction of iron and zinc was 67 and 100 %, respectively. Reduction mechanism was explored after applying XRD, XRF and thermodynamics analysis. It was found that the reduction reaction was an ion reaction. The AlN and heavy metal oxide transformed into anionic group containing nitrogen and heavy metal cation, after entering slag. The heavy metals were reduced into alloy after electron was transferred from anionic group to cation. In addition, the reduced iron and zinc could merge into alloy, which inhibited evaporation of zinc. Yellow transparent glass was obtained after the reduction process. Yellow was come from titanium oxide, which could not be reduced by AlN. Microhardness, density and water absorption of the transparent glass were 741 HV, 2.86 g·cm -3 and 0.04 %, respectively. Leaching content of Ni, Cu, Zn and Pb of the glass were 0.1, <0.1, 0.6 and < 0.1 mg/L, respectively, all below the TCLP limit. About 115 ∼ 213 dollars were earned after manufacturing 500 kg of MSWI fly ash into transparent glass. This work provided a novel idea of recycling solid waste into alloy and transparent glass for building., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

H 2 O in flue gas causes the deactivation of V 2 O 5 /TiO 2 catalysts for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures. Developing water resistance requires understanding the theoretical mechanism of H 2 O impact on the catalysts. The aim of this work was to clarify the adsorption process of H 2 O and the deactivation mechanism induced by H 2 O through density functional theory (DFT). The process of H 2 O adsorption was studied based on a modeled V 2 O 5 /TiO 2 catalyst surface. It was found that H 2 O had a strong interaction with exposed titanium atoms. Water adsorption on the catalyst surface significantly alters the electronic structure of VO x sites, transforming Lewis acid sites into Brønsted acid sites. Exposed titanium sites contribute to the decrease of Lewis acidity via adsorbed water. Ab initio thermodynamic calculations show that H 2 O adsorption on V 2 O 5 /TiO 2 is stable at low coverage but less favorable at high coverage. Adsorption of NH 3 is the most critical step for the SCR of NO x , and the adsorption of H 2 O can hinder this process. The H 2 O coverage below 15% of adsorption sites could enhance the NH 3 adsorption rate and have a limited effect on the acidity, while higher coverage impeded the adsorption ability of VO x sites. This work provided electron-scale insight into the adsorption impact of H 2 O on the surface of V 2 O 5 /TiO 2 catalysts, presented thermodynamic analysis of the adsorption of H 2 O and NH 3 , paving the way for the exploration of V 2 O 5 /TiO 2 catalysts with improved water resistance.

Platinum group metals (PGMs) are strategic metals. Auto-exhaust catalysts are their main application fields. The recovery of PGMs from spent auto-exhaust catalysts has remarkable economic value and strategic significance. Aiming at the problems of ferrosilicon generation for Fe capturing and subsequent oxygen blowing to remove iron with high energy consumption and heat release, a technology of Fe-Sn synergistic capturing PGMs was proposed. Taking full the advantage of the lower melting point of Fe-Sn alloy (<1200 °C) and its unique affinity for PGMs, the PGMs were captured at approximate 1400 °C with Fe-Sn as the collector. In experiment, 500 g of spent auto-exhaust catalysts were employed to minimize error and approximate industrial production. The mechanism of Fe-Sn synergistic capturing PGMs was elucidated. The generation of Fe-Sn-PGMs alloy lowered the activity of [PGMs] in the system, accelerated the reduction of the PGMs oxides and promoted the alloying of [PGMs]. Therefore, Fe-Sn synergistic capturing PGMs was realized. The inability of Si to enter the alloy phase was confirmed by theoretical calculations, avoiding the generation of ferrosilicon. The effects of basicity, CaF 2 , m(Fe)/m(Sn) and the amount of collector on capturing PGMs were optimized. Under the optimized conditions (basicity R = 1.1, spent auto-exhaust catalysts 70 wt%, CaO 30 wt%, B 2 O 3 10 wt%, CaF 2 7 wt%, m(Fe)/m(Sn) = 1/1 and the collector 15 wt%), the content of PGMs in the slag phase was 2.46 g/t. It is feasible to remove Fe and Sn by oxidation to achieve the purpose of PGMs enrichment. This technology offers guidance on the safe, environmentally sound, and efficient disposal of spent auto-exhaust catalysts, promoting the sustainable development of PGMs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Concrete is the main ingredient in construction, but it inevitably fractures during its service life, requiring a large amount of cement and aggregate for maintenance. Concrete healing through biomineralization can repair cracks and improve the durability of concrete, which is conducive to saving raw materials and reducing carbon emissions. This paper reviews the biodiversity of microorganisms capable of precipitating mineralization to repair the concrete and their mineralization ability under different conditions. To better understand the mass transfer process of precipitates, two biomineralization mechanisms, microbially-controlled mineralization and microbially-induced mineralization, have been briefly described. The application of microorganisms in the field of healing concrete, comprising passive healing and intrinsic healing, is discussed. The key insight on the interaction between cementitious materials and microorganisms is the main approach for developing novel self-healing concrete in the future to improve the corrosion resistance of concrete. At the same time, the limitations and challenges are also pointed out., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The increasing scrapped Si-based photovoltaic (PV) panels has become an urgent problem, and their disposal is essential for resources utilization and environment issues. This paper proposes a comprehensive process for recycling of discarded silicon-based PV panels economically, environmentally, and efficiently. Based on the thermal properties of ethylene vinyl acetate (EVA), they are removed from the discarded PV panels at 600 °C with heating rate of 5 °C/min and maintain for one hour. The glass, solar cells, and copper strips were separated after heat treatment. Simultaneously, the solar cells were crushed into powder. Nitric acid was used to recover silver from the solar cell powder, while most of the metal impurities such as Mg, Ti and Al, were removed as well. The leaching efficiency of silver was over 96 % under the optimized conditions: HNO 3 of 4.0 mol/L, liquid-to-solid ratio of 10:1, temperature of 50 °C for 80 min. Regarding the copper strips, they were sequentially treated with 0.5 mol/L CH 3 COOH and NaOH solution to remove the oxides of Pb and Sn on their surface. Subsequently, they were placed into the solution of 1.0 mol/L CuSO 4 with pH of 2 ∼ 3 to eliminate Pb and Sn. This article provides significant reference for the recycling of Si-based PV panels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Inverse lithography technique (ILT) is a leading-edge method to improve the image fidelity of an advanced optical lithography system by performing pixel-wise optimization on the transmission function of photomask. However, traditional ILTs are computationally intensive, which limits their application in high volume manufacturing of integrated circuits. This paper proposes a model-driven graph convolutional network (MGCN) framework combined with the dense concentric circular sampling (DCCS) method to effectively improve computational efficiency and imaging fidelity of current ILTs. Firstly, the DCCS template is used to extract the geometric features from the layout pattern of integrated circuits, which are then input into a GCN-based encoder to predict the optimized mask pattern of the ILT. Then, a model-driven decoder based on the lithography imaging process is developed to retrieve the print image of the predicted ILT mask. By means of the cooperation between the encoder and decoder, an unsupervised training strategy is proposed to avoid the time-consuming labelling process of the training samples. With the help of the parallel computing under GPU framework, the well-trained encoder can make a fast prediction of ILT mask with high-fidelity image results. The results demonstrate the state-of-the-art performance of the proposed MGCN approach compared to some other comparative ILT methods.

Safety and efficient dispose of municipal solid waste incineration (MSWI) fly ash with high toxicity has emerged as a worldwide challenge. Vitrification provides the advantages of capacity reduction, detoxification, and solidification of heavy metals, which has the potential to dispose of hazardous waste on a large scale. Herein, co-vitrification of MSWI fly ash and bottom slag has been accomplished based on the characteristics of calcium and silicon composition. A novel approach for producing glass ceramic foams by alkaline activation-crystallization was developed to realize the disposal of the obtained glass. The effect of MSWI fly ash/bottom slag ratios on the glass network, crystallization ability of the basic glass, pore structure, and physical properties of the porous green body was investigated. The results revealed that with increasing MSWI fly ash proportion, the Si-O of [SiO 4 ] in the basic glass changed significantly and the crystallization ability steadily reduced. Si-O and Al-O in basic glass are easy to corrode under alkaline conditions, releasing Ca 2+ and forming a low solubility product, calcium silicate hydrate. When the crystallization temperature increases from 950 ℃ to 1150 ℃, it is more conducive to the precipitation of the gehlenite phase. Extending the crystallization time promotes three-dimensional growth of crystals that are coupled with each other to form a network structure and a multi-stage pore structure. The pore structure was developed with the help of NH 3 and H 2 generated by the secondary aluminum ash (SAA). Through the preparation of glass ceramic foams, the raw materials were detoxified. The toxic heavy metals showed extremely low leaching concentrations, which were smaller than the limit of TCLP. The prepared samples had 70.22-80.61% of porosity, 0.78-1.19 g/cm 3 of low bulk density, and 0.54-7.86 MPa of compressive strength., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Recovery of platinum group metals (PGMs) from secondary resources has attracted worldwide attention from environmental and economic points of view. Pyrometallurgical routes exhibit the superiority in terms of efficiency and contamination control compared to hydrometallurgical process. However, traditional pyrometallurgical processes face the challenges of excessive flux and energy consumption. In this paper, an iron capture process was proposed to recover low-grade PGMs from leaching residue of spent auto-exhaust catalysts. Slag design was explored aimed at reducing the addition amount of flux. The optimized smelting conditions were as follows: 1400 °C for 30 min, adding 40.0 wt% CaO, 22.7 wt% Na 2 CO 3 , 5.0 wt% Na 2 B 4 O 7 , 5.0 wt% CaF 2 , 15.0 wt% Fe, and 5.0 wt% C. The concentrations of Pt, Pd and Rh remaining in the smelting slag were 0.83 g/t, 4.99 g/t, and 1.47 g/t, respectively. Furthermore, the 50 kg-scale experiment implied positive economic feasibility because of saving flux dosage and smelting time. The capture mechanism was revealed by investigating the formation of the metals phase and slag phase. Matrix formed slag phase and separate with metals phase owing to differences in chemical bonding, density, viscosity, and surface tension. PGMs were proved solubilized in α-Fe as substitutional solid solutions. The formation energies for FePt, FePd, and FeRh alloys were -4.149 eV, -4.040 eV, and -4.360 eV, respectively. Finally, the obtained CaO-SiO 2 -Al 2 O 3 -Na 2 O glass slag was used for producing glass ceramics. To sum up, the iron capture process realized low energy and material consumption, high recovery efficiency of PGMs, and resource utilization of the glass slag., Competing Interests: Declaration of competing interest The authors declared that they have no conflicts of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Source and mask optimization (SMO) is a widely used computational lithography technology that greatly improves the image fidelity of lithography systems. This paper develops an efficient informatics-based SMO (EISMO) method to improve the image fidelity of lithography systems. First, a communication channel model is established to depict the mechanism of information transmission in the SMO framework, where the source is obtained from the gradient-based SMO algorithm. The manufacturing-aware mask distribution is then optimized to achieve the best mutual information, and the theoretical lower bound of lithography patterning error is obtained. Subsequently, an efficient informatics-based method is proposed to refine the mask optimization result in SMO, further reducing the lithography patterning error. It is shown that the proposed EISMO method is computationally efficient and can achieve superior imaging performance over the conventional SMO method.

Secondary aluminum dross (SAD) from aluminum industry is classified as a hazardous solid waste due to containing aluminum nitride (AlN). In this work, AlN was first used to reduce heavy metals by pyrometallurgy. The reduction rates for iron, chromium and nickel were up to 90%, 80% and 100%, respectively. However, the reduction from AlN and oxygen oxidization of AlN occurred simultaneously. AlN which formed solid solution with alumina could reduce heavy metals, while the rest was oxidized by oxygen. In addition, the reduction rates for iron and chromium could be increased with increasing CaF 2 from 6.7 to 9.0 wt%. CaF 2 could decreased viscosity of molten slag, which favored the ion migration, and then increased the reduction rates. After the reduction, glass ceramics were manufactured from the molten slags. The bending strength, microhardness and alkali resistance of the glass ceramics were up to 77 MPa, 1011 HV and 98.7%, respectively. According to XRD and SEM results, glass ceramics with CaAl 2 SiO 6 crystal phase, crosslinked network structure grains and smaller pores exhibited better bending resistance. In addition, glass ceramics with CaAl 2 SiO 6 crystal phase possessed the highest microhardness and alkali resistance. After this process, hazardous pickling sludge and SAD were totally recycled., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The safe utilization of solid wastes containing heavy metals plays a crucial role in environmental preservation. As an efficient technology to achieve this goal, the preparation of glass ceramic foams from solid wastes can produce an excellent solidification effect on heavy metals. At present, there have been plenty of efforts made to achieve an excellent combination of such characteristics as mechanical strength, bulk density, thermal conductivity and so on, with the purpose to ensure the application in various high value-added fields. Due to the concentration on their application in the construction sector such as the use of thermal and acoustic insulation materials, some researchers seek to expand the scope of their applications. In this paper, a review is conducted into the methods used to prepare solid waste-based glass ceramic foams. Depending on the exact processing route, these methods can be categorized into two classes, which are powder sintering and inorganic gel casting. Not only heavy metals hinder the application of solid waste, they can also cause irreversible pollution to the wider environment. Solidification and volatilization represent the two routes associated with heavy-metal migration during the preparation of glass ceramic foams. Both traditional and innovative applications are indicated in this review. Furthermore, a discussion is conducted about the prospects and challenges facing different processing strategies, heavy-metal migration and applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

For nanofibrous aerogels, a three-dimensional porous structure with interwoven nanofibers as a pore wall has become an urgent demand, and it remains to be a challenge to ensure the mechanical stability and thermal insulation. Other than the reported nanofiber as raw materials to generate three-dimensional cellular nanofibrous aerogels, an alternative low-cost and facile procedure has been proposed here via tactfully utilizing polymer sponge as a template attached with reactive particles, followed by a carbothermal reduction process to realize nanowire growth and their replacement of the original framework. The resulting spongy aerogels with numerous interlaced SiC/Si 3 N 4 nanowires as a skeleton exhibit an ultrahigh porosity of 99.79%. Meanwhile, compressive elasticity after a compression at strain of 35% for 400 cycles, a low thermal conductivity of 23.19 mW/(m K), an excellent absorption capacity of 33.9-95.3 times for varied organic solvents removal, along with flexibility in shape design favored by the initial organic sponge make this nanofibrous aerogel an ideal material for heat shielding, absorption, or catalyst support.

Secondary aluminum dross (SAD) is solid waste of primary aluminum dross extracted aluminum, which contains approximately 40-60 wt% alumina, 10-30 wt% aluminum nitride (AlN), 5-15 wt% salts and other components. The salts include sodium chloride, potassium chloride and fluorine salts. SAD has dual attributes as resource and pollutant. SAD landfill disposal has the disadvantages of occupying land, wasting resources, a high cost and great environmental impact. SAD utilization methods are currently pyrometallurgy and hydrometallurgy. In pyrometallurgy, AlN is oxidized and the salts are evaporated at high temperature. After mixing, molding and calcination, firebricks and ceramics can be manufactured from SAD. In hydrometallurgy, AlN is hydrolyzed and salts are dissolved in water. After dissolving, filtrating, precipitating, washing and calcination, γ-Al 2 O 3 can be prepared from SAD. Resource consumption and emission from both utilization methods were assessed. A ton of magnesium aluminum titanate based ceramics by pyrometallurgy consumes 1043 kg raw materials and releases 69 kg of waste gas, 4.17 t of waste water and no solid waste. A ton of γ-Al 2 O 3 by hydrometallurgy consumes 3389 kg raw materials and releases 111 kg of waste gas, 12.98 t of waste water and 267 kg of solid waste. Therefore, the resource consumption and emission of SAD utilization by pyrometallurgy is lower than that by hydrometallurgy. We should focus on reducing the emission of the three wastes from pyrometallurgy. We are sure that SAD can be utilized for glass ceramics by pyrometallurgy. AlN and salts can be transformed into alumina and glass phases at high temperature with no emission. We should clarify mechanisms for SAD composition adjustment to lower the glass ceramics' melting point, AlN and salts transformed into alumina and glass phases respectively, and nucleation and crystal growth of glass ceramics at high temperature., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled Review., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Photolithography is at the core of the semiconductor industry that is used to fabricate microscale and nanoscale integrated circuits. Inverse lithography is a technique extensively used to compensate for lithography patterning distortions. It refers to methods that pre-distort the photomask patterns such that their projection, through the photolithography system, results in a pattern that is as close as possible to the intended original. However, most inverse lithography technique (ILT) methods suffer from large computational complexity. This paper develops a nonlinear compressive sensing framework for ILT that effectively improves the computational efficiency and image fidelity, while at the same time controlling the mask complexity. Based on a nonlinear lithography imaging model, the compressive ILT is formulated as an inverse optimization problem aimed at reducing the patterning error, and enforcing the sparsity and low rank properties of the mask pattern. A downsampling strategy is adopted to reduce the dimensionality of the cost function, thus alleviating the computational burden. Sparsity and low-rank regularizations are then used to constrain the solution space and reduce the mask complexity. The split Bregman algorithm is used to solve for the inverse optimization problem. The superiority of the proposed method is verified by a set of simulations and comparison to traditional ILT algorithms.

This paper proposes a new method for producing nano-SrFe 12 O 19 powder by the citrate precursor route using solid waste as a source of iron. This solid iron-containing waste, which exists in the form of an oily sludge, is produced by a cold rolling mill. This sludge was first subjected to a process, including sulfuric acid leaching, oxidation, precipitation, and nitric acid leaching, to obtain an iron nitrate (Fe(NO 3 ) 3 ) solution. Next, the Fe(NO 3 ) 3 solution was mixed with a strontium nitrate (Sr(NO 3 ) 2 ) solution obtained by subjecting strontium carbonate to nitric acid leaching. Subsequently, citric acid, as chelating agent, and ammonia water, as precipitating agent, were added to the mixed solution to form a gel. The gel was dried and spontaneously combusted, then annealed at different temperatures for 2 h in flowing air. The effects of the Fe 3+ /Sr 2+ molar ratio and annealing temperature on the formation, morphology, and magnetic properties of SrFe 12 O 19 were investigated. The results showed that single-phase SrFe 12 O 19 powder was obtained by decreasing the Fe 3+ /Sr 2+ molar ratio from the stoichiometric value of 12 to 11.6 and increasing the annealing temperature to 1000 °C for 2 h. Adjustment of the Fe/Sr molar ratio to 12 and the annealing temperature to 900 °C enabled the magnetic properties to be optimized, including saturation magnetization (Ms) 80.2 emu/g, remanence magnetization (Mr) 39.8 emu/g, and coercive force (Hc) 6318 Oe.

Reclamation of spent catalysts for the efficient recovery of palladium (Pd) is gaining growing attention due to its scarcity and high supply risk. Currently Pd extraction from spent catalysts through an efficient, economical, and green method has remained a challenge. In this study, Fe 3+ is utilized for leaching through oxidation of Pd in a mild condition. Before leaching, distillation was proposed to remove and recover the organics from spent catalysts. The effects of HCl concentration, Fe 3+ concentration, NaCl concentration, leaching time, and temperature on the leaching efficiency of Pd were investigated to determine the optimum leaching conditions. The results show that Pd extraction and dissolution of Al 2 O 3 increase with higher HCl concentration. The effect of NaCl on Pd leaching efficiency is significant at low acid concentration (2.0 mol/L HCl). The leaching efficiency was 99.5% for Pd under the following conditions: 2.0 mol/L HCl, 4.0 mol/L NaCl, and 0.67 mol/L Fe 3+ at 80 °C for 90 min. The leaching kinetics fits best to the shrinking-core model of surface chemical reaction. The activation energy for the leaching of Pd was 47.6 kJ/mol. PdCl 4 2- was selectively adsorbed by anion exchange resin. The filtrate containing adequate H + , Cl - , and Fe 3+ was reused as leaching agent. Pd leaching efficiency was over 96% after five cycle times. This study provides an efficient process for recovery of Pd from spent catalysts.

A series of Mn-based catalysts were prepared by a wet impregnation method for the selective catalytic reduction (SCR) of NO with NH 3 . The Mn/Ti-Zr catalyst had more surface area, Lewis acid sites, and Mn 4+ on its surface, and showed excellent activity and high N 2 selectivity in a wide temperature range. NH 3 and NO oxidation was investigated to gain insight into NO reduction and N 2 O formation. The formation of N 2 O was primarily dominated by the reaction of NO with NH 3 in the presence of O 2 via the Eley-Rideal mechanism. An intimate synergistic effect existed between the Mn-based and the Ti-Zr support. It was demonstrated that the Ti-Zr support greatly promoted the catalytic performance of Mn-based catalysts., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

New development and technological innovations make electrical and electronic equipment (EEE) more functional by using an increasing number of metals, particularly the critical metals (e.g. rare and precious metals) with specialized properties. As millions of people in emerging economies adopt a modern lifestyle, the demand for critical metals is soaring. However, the increasing demand causes the crisis of their supply because of their simple deficiency in the Earth's crust or geopolitical constraints which might create political issues for their supply. This paper focuses on the sustainable supply of typical critical metals (indium, rare earth elements (REEs), lithium, cobalt and precious metals) through recycling waste electrical and electronic equipment (WEEE). To illuminate this issue, the production, consumption, expected future demand, current recycling situation of critical metals, WEEE management and their recycling have been reviewed. We find that the demand of indium, REEs, lithium and cobalt in EEE will continuously increasing, while precious metals are decreasing because of new substitutions with less or even without precious metals. Although the generation of WEEE in 2014 was about 41.9 million tons (Mt), just about 15% (6.5 Mt) was treated environmentally. The inefficient collection of WEEE is the main obstacle to relieving the supply risk of critical metals. Furthermore, due to the widespread use in low concentrations, such as indium, their recycling is not just technological problem, but economic feasibility is. Finally, relevant recommendations are point out to address these issues., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Safe disposal of solid wastes containing heavy metals is a significant task for environment protection. Immobilization treatment is an effective technology to achieve this task. Cementitious material treatments and thermal treatments are two types of attractive immobilization treatments due to that the heavy metals could be encapsulated in their dense and durable wasteforms. This paper discusses the heavy metal immobilization mechanisms of these methods in detail. Physical encapsulation and chemical stabilization are two fundamental mechanisms that occur simultaneously during the immobilization processes. After immobilization treatments, the wasteforms build up a low permeable barrier for the contaminations. This reduces the exposed surface of wastes. Chemical stabilization occurs when the heavy metals transform into more stable and less soluble metal bearing phases. The heavy metal bearing phases in the wasteforms are also reviewed in this paper. If the heavy metals are incorporated into more stable and less soluble metal bearing phases, the potential hazards of heavy metals will be lower. Thus, converting heavy metals into more stable phases during immobilization processes should be a common way to enhance the immobilization effect of these immobilization methods., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Waste electrical and electronic equipment (WEEE) has been one of the fastest growing waste streams worldwide. Effective and efficient management and treatment of WEEE has become a global problem. As one of the world's largest electronic products manufacturing and consumption countries, China plays a key role in the material life cycle of electrical and electronic equipment. Over the past 20 years, China has made a great effort to improve WEEE recycling. Centered on the legal, recycling and technical systems, this paper reviews the progresses of WEEE recycling in China. An integrated recycling system is proposed to realize WEEE high recycling rate for future WEEE recycling., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y0.95Eu0.05)2O3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy., (Copyright © 2013. Published by Elsevier Ltd.. All rights reserved.)

Photoelectrode made of nanocable structure of ZnO nanorods (NR) coated with TiO(2) nanosheets (NSs) was investigated for CdS/CdSe quantum dot co-sensitized solar cells. ZnO NRs prepared solution reaction at 60 °C served as the backbone for direct electron transport in view of the single crystallinity of the ZnO NRs and the high electron mobility of ZnO semiconductor. Anatase TiO(2) NSs with the thickness of ∼10 nm and the length of ∼100 nm were assembled onto the surface of ZnO NRs via a solvothermal method. It was found that the thin shell of TiO(2) might have remarkable influence on the quantum dot sensitized solar cells (QDSCs) through (a) increasing the surface area of ZnO NRs to allow for adsorbing more quantum dots (QDs), which led to high short current density, (b) forming an energy barrier that hindered the electrons in the ZnO from being back to the electrolyte and QDs, and thus, reduced the charge recombination rate, resulting in prolonged electron lifetime and enhanced open voltage. In comparison with the case of ZnO NRs, the short-circuit current density, open-circuit voltage, fill factor and charge recombination resistance of ZnO/TiO(2) nanocable photoelectrode increase by 3%, 44%, 48% and 220%, respectively. As a result, a power conversion efficiency of 2.7% of QDSCs with core-shell structural nanocable photoelectrode has been obtained, which is as much as 230% of that of 1.2% obtained for ZnO NR photoelectrode.