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With the widespread photovoltaic deployment to achieve the net-zero energy goal, the resulting photovoltaic waste draws attention. In China, considerable steps have not been taken for photovoltaic waste management. The lack of relevant scientific information on photovoltaic waste brings difficulties to the establishment of photovoltaic waste regulatory systems. In this study, the necessity and feasibility of photovoltaic waste recovery were investigated. In China, the photovoltaic waste stream was quantified as 48.67-60.78 million t in 2050. In photovoltaic waste, indium, selenium, cadmium, and gallium were in high risk, judging by the metal criticality analysis, which meant that their recovery was significant to alleviate the resource shortage. The full recovery method was proved to reduce the environmental burdens most. For cost and benefit analysis, the net present value/size was -1.02 $/kg according to the current industrial status. However, it can be profitable with the recovery of silver. This study provides scientific and comprehensive information for photovoltaic waste management in China and is expected to promote the sustainable development of photovoltaic industry.

As a major part of municipal waste, the amount of waste glass has greatly increased. Due to its stable physical and chemical properties, glass can be effectively recycled with very little loss of quality. Meanwhile, recovery of waste glass is considered to be meaningful for saving resources and energy for sustainable development. However, remanufacturing processes always need a higher level of cleaning of waste glass. Traditionally, the combination technology of hydraulic cleaning and semimanual sorting is used to clean the organic and metallic impurities of waste glass. This combination technology has the disadvantages of low efficiency and producing lots of organic wastewater, which causes heavy environmental pollution. This study proposed an environmental-friendly combined recycling system of waste glass. Waterless cleaning, iron removing, eddy current separation, and optical separation were combined to realize the cleaning and sorting of waste glass. The operation parameters of each process of this new system were discussed and optimized. This system contributed to a high-efficiency and environmental-friendly way for the recovering of waste glass in municipal wastes, and it is an engineering practice to upgrade the urban solid waste recycling technology.

Recovering valuable materials from spent lithium-ion batteries is an important task because of the asymmetry in resource distribution, supply, and demand around the world. A lithium-ion battery is a combination system of various elements and their oxides. Current recovering technologies focus on the separation of valuable metal elements. They can inescapably bring secondary contamination and cost to the environment due to the addition of leachants and precipitants. To recover valuable materials, in situ recombination of elements in spent lithium-ion batteries can be a more economical and environment-friendly solution. Herein, we developed a technology based on in situ aluminothermic reduction and interstitial solid solution transformation to recover high-value I³-LiAlO2 and LiAl5O8 under vacuum and high-temperature (1723 K) conditions. It was found that the process of Li2O filling into the lattice of O-Al-O structure is an energy-reducing process, while LiAl5O8 was an existing high-energy transition-state matter. Since there was no wastewater generated, the process brought a new environment-friendly method for recovering valuable metals from spent lithium-ion batteries. This study also provides new comprehension regarding the design for high-value products' recovery from multi-element mixed wastes on an atomic scale.

Waste printed circuit boards (WPCBs) are not only valuable recourses but also hazardous materials. Mechanical crushing is an essential pretreatment for WPCB recycling. Polybrominated diphenyl ether...

In this study, phosphoric acid and hydrogen peroxide systems were used to recover manganese from the positive electrode material of zinc–manganese dry batteries. Factors influencing leaching reacti...

Inductive effect, although originally proposed in the field of organic chemistry, has long been regarded as an effective way to increase the working potential of inorganic lithium-ion battery catho...

The increasingly large stream of e-waste is seriously threatening the environment; meanwhile, global energy shortage is on the rise. Based on the principles of energy regeneration and waste utilization, we introduced a win-win approach to utilize waste capacitors for construction of magnetic and core-shell Z-scheme Nb-Pb-codoped BaTiO3/Ni-Pd@graphite-like carbon nitride (g-C3N4) photocatalysts for H2 evolution. Using simple ball-milling, waste capacitors were transformed to Nb-Pb-codoped BaTiO3/Ni-Pd-Ag-Sn nanoparticles and g-C3N4 was coated on the nanoparticles, forming a core-shell structure. The Ni-Pd acted as the electron mediator in the Z-scheme, and Ag-Sn also facilitated the electron transfer. Moreover, Ni made the Z-scheme magnetically separable. The Z-scheme showed a remarkably enhanced photocatalytic H2 evolution rate, which was 22.2 times higher than that of g-C3N4. Such an enhanced photocatalytic performance was attributed to the special Z-scheme and core-shell structure, improving the light adsorption, increasing the Brunauer-Emmett-Teller (BET) surface area, facilitating the efficient separation of electron-hole pairs, and maintaining the strong redox ability of charge carriers. Furthermore, the photoluminescence analysis combined with density functional theory (DFT) calculations provided the basis for the Z-scheme mechanism. This study adequately utilized the composition of e-waste to construct a highly efficient and magnetically separable Z-scheme for H2 generation, which realizes energy regeneration, waste recycling, and environmental protection.

Biocyanidation is an environment-friendly technology for recovering precious metals from waste printed circuit boards (WPCBs). Although the leaching mechanism has been studied a lot, Au-release behavior still remains unknown. In this paper, density functional theory (DFT) was employed to investigate the electronic structure of the complex existing in the Au cyanidation process. Extended charge decomposition analysis (ECDA) showed that the adsorption of CN– to Au and the adsorption of O to the formed [AuCN]⁻ caused net electron transfer of 0.356 and 0.574 au, respectively. Dissociation of O from [AuCNO]⁻ had a Gibbs free energy change of −154.229 kcal/mol. Electron localization function (ELF) and localized orbital locator (LOL) confirmed that CN– covalent bonding led to a transformation of the orbit localization region of the adsorbed Au atom. It might cause electrostatic repulsion from the nondirectly contacted Au atom. This speculation was demonstrated by the Mulliken overlap population analysis, which showed that CN– bonding caused antibonding interaction. The repulsive interaction would be an important factor triggering the release of the adsorbed Au atom. This work presented a new interpretation of Au cyanidation, providing important insights into Au-release behavior. It might help construct the leaching kinetics of multimetal resources to facilitate the recovery of precious metals from waste printed circuit boards.

Polyethylene glycol terephthalate and ethylene-vinyl acetate copolymer are applied as packaging materials in solar cells. Abundant polyethylene glycol terephthalate and ethylene-vinyl acetate copol...

Waste printed circuit boards (WPCBs) are hazardous wastes but also valuable resources. Mechanical crushing is widely used to recycle WPCBs. Some pollutants are released during the crushing, but the...

Increased generation of spent lithium-ion batteries (LIBs) has driven the exploration of new methods for reusing and/or recycling LiCoO₂ cathode materials. Herein, an electrochemical relithiation method was proposed to directly regenerate LiCoO₂ cathode materials using the waste LiₓCoO₂ electrode as a base. It was shown that Li⁺ was successfully inserted into the waste LiₓCoO₂ electrode, and this relithiation process became faster with either a higher Li₂SO₄ concentration or a higher cathodic current density. The XRD analysis confirmed that the peak positions of the relithiation products were consistently close to those of a standard LiCoO₂ material. The crystal structure of the relithiation products was restored with a post-annealing process. The activation energy for electrochemical relithiation (Eₐ) was estimated at 22 kJ mol–¹, and the constant of equilibrium constant k₀ was determined as 1.35 × 10–⁶ cm s–¹. The relithiation process was controlled by the charge transfer process when the Li₂SO₄ concentration was high (e.g., 1, 0.8, and 0.5M), and a lower concentration at 0.01–0.3 M led to a diffusion control pattern. The electrode made of the regenerated LiCoO₂ materials had a charge capacity of 136 mAh g–¹, close to that of the commercial LiCoO₂ electrode (140 mAh g–¹). A potential mechanism of electrochemical relithiation was proposed involving lithium defects, relithiation, and crystal regeneration.

The effects of anion charge and lattice volume (lithium–anion bond length) on lithium ion migration have been investigated by utilizing the density functional theory calculations combined with the ...

From the environmental safety and resource recovery viewpoint, a novel method of recycling gallium arsenide (GaAs) from scrapped GaAs-based integrated circuits (ICs) was proposed in this study. A h...

Spent lithium ion battery (LIB) recovery is becoming quite urgent for environmental protection and social needs due to the rapid progress in LIB industries. However, recycling technologies cannot keep up with the exaltation of the LIB market. Technological improvement of processing spent batteries is necessary for industrial application. In this paper, spent LIB recovery processes are classified into three steps for discussion: gathering electrode materials, separating metal elements, and recycling separated metals. Detailed discussion and analysis are conducted in every step to provide beneficial advice for environmental protection and technology improvement of spent LIB recovery. Besides, the practical industrial recycling processes are introduced according to their advantages and disadvantages. And some recommendations are provided for existing problems. Based on current recycling technologies, the challenges for spent LIB recovery are summarized and discussed from technological and environmental perspectives. Furthermore, great effort should be made to promote the development of spent LIB recovery in future research as follows: (1) gathering high-purity electrode materials by mechanical pretreatment; (2) green metals leaching from electrode materials; (3) targeted extraction of metals from electrode materials.

Based on density functional theory calculations of iodide-type compounds Li3MI6 (M = Sc, Y, and La), Li3LaI6 with stable octahedral Li occupation is theoretically found to meet the requirements of ...

Integrated circuits (ICs) are widely used in all the electrical and electronic equipment, and the recycling technology of ICs has been poorly developed. This study proposes a promising process to d...

The demand for gold in the field of national storage, jewelry, and electronics has never been higher. However, gold extraction is not always welcomed by local residents because of the resulting environmental contamination. For more than a century, cyanide and aqua reiga were dominantly used for gold mining because of their low costs, high efficiencies, and easy operations. In this article, an improved chlorination process, a traditional cyanidation process, and a traditional aqua regia process were quantitatively analyzed and compared from the perspective of environmental impact. The Biwer-Heinzle method is employed. The results showed that the improved chlorination process had the lowest environmental hazard. The values of General Environmental Indices computed for the Inputs and Outputs were quite small, closing to the minimum values of 0 and 1, respectively, depending on the calculation approach used, via arithmetic average or via multiplication. The results also revealed that the aqua regia process ha...

The effects of anion charge and lattice volume (lithium-anion bond length) on lithium ion migration have been investigated by utilizing the density functional theory calculations combined with the anion framework models, e.g. fcc, hcp and bcc. It is found that the anion charge and lattice volume have great impacts on the activation energy barrier (Ea) of lithium ion migration, which is validated by some reported sulfides. For the tetrahedrally occupied lithium, the less negative anion charge is, the lower the lithium ion migration barrier is likely to be. While for the octahedrally occupied lithium, the more negative anion charge is, the lower the lithium ion migration barrier is. The large lattice volume (lithium-anion bond length) can lower Ea to a certain extent. Lithium ion direct migrations along the direct Tet-Tet pathway in the bcc- or hcp-type anion framework are less sensitive to anion charge and lattice volume than other pathways. Most importantly, based on the full understandings of anion framework model, new design rules for developing alkali-metal superionic conductors were proposed. Getting the desired electronegativity difference between the anion element and non-mobile cation element by selecting the most suitable non-mobile cation element without changing the crystal structure framework can eventually achieve low Ea for alkali-metal ion migration. For the desired alkali-metal superionic conductors with tetrahedrally occupied alkali-metal ions, the fine non-mobile cation element should give preferences to those elements located at the right top of the periodic table of elements with large electronegativities. For the alkali-metal superionic conductors with octahedrally occupied alkali-metal ions, the fine non-mobile cation element should give preferences to the elements located at the left bottom of the periodic table with small electronegativities.

The effects of anion charge and lattice volume (lithium-anion bond length) on lithium ion migration have been investigated by utilizing the density functional theory calculations combined with the anion framework models, e.g. fcc, hcp and bcc. It is found that the anion charge and lattice volume have great impacts on the activation energy barrier (Ea) of lithium ion migration, which is validated by some reported sulfides. For the tetrahedrally occupied lithium, the less negative anion charge is, the lower the lithium ion migration barrier is likely to be. While for the octahedrally occupied lithium, the more negative anion charge is, the lower the lithium ion migration barrier is. The large lattice volume (lithium-anion bond length) can lower Ea to a certain extent. Lithium ion direct migrations along the direct Tet-Tet pathway in the bcc- or hcp-type anion framework are less sensitive to anion charge and lattice volume than other pathways. Most importantly, based on the full understandings of anion framework model, new design rules for developing alkali-metal superionic conductors were proposed. Getting the desired electronegativity difference between the anion element and non-mobile cation element by selecting the most suitable non-mobile cation element without changing the crystal structure framework can eventually achieve low Ea for alkali-metal ion migration. For the desired alkali-metal superionic conductors with tetrahedrally occupied alkali-metal ions, the fine non-mobile cation element should give preferences to those elements located at the right top of the periodic table of elements with large electronegativities. For the alkali-metal superionic conductors with octahedrally occupied alkali-metal ions, the fine non-mobile cation element should give preferences to the elements located at the left bottom of the periodic table with small electronegativities.

Germanium, because of its unique performance, has been widely used in the manufacture of optical fiber. Recycling germanium is significant because of geographical scarcity and technical barriers. I...

Sulfide-type solid-state electrolytes for all-solid-state lithium ion batteries are capturing more and more attention. However, the electronegativity difference between the oxygen and the sulfur element makes sulfide-type solid-state electrolytes chemically incompatible with the conventional LiCoO2 cathode. In this work, we proposed a series of chalcopyrite-structured sulfide-type materials and systematically assessed their performances as the cathode materials in all-solid-state lithium ion batteries by first-principle calculations. All the five metallic LiMS2 (M = Cr, Mn, Fe, Co, and Ni) materials are superionic conductors with extremely small lithium ion migration barriers in the range from 43 to 99 meV, much lower than most oxide- and even sulfide-type cathodes. Voltage and volume calculations indicate that only LiCrS2 and LiMnS2 cathodes are structurally stable during cycling with the stable voltage plateaus at ∼3 V, much higher than that of the P3m1-LiTiS2 cathode. For the first time, we studied the...

Waste tuning fork crystal resonators (WTFCRs), as essential components of electronic products, are resource-rich but hazardous, demanding to be safely recycled and disposed to promote sustainable u...

Metallized film capacitors (MFCs) are widely applied in electronic appliances. The rapid replacement of electronic products leads to producing a great many waste MFCs. Waste MFCs, containing organics (plastic dielectric and brominated epoxy resin) and metals (zinc, copper, iron, etc.), are not only considered as hazardous waste but also a valuable resource for recycling. However, how to recycle waste MFCs effectively is seldom considered. This work provided an integrated technology for recovering waste MFCs. First, waste MFCs were treated by pyrolysis to recycle the organics. The decomposition characteristic, product, and mechanism of the organics were studied. A pyrolysis temperature of 500 °C and holding time for 30 min were determined as the optimal parameters. Then, the residues were conducted by grinding and screening to recover copper–iron electrodes. Finally, hexagonal flake-like zinc powder with a particle size of 15 μm was recovered by vacuum metallurgy separation (VMS). The VMS principle for rec...

The contradiction of energy, resource, and environment from waste LCD panels is prominent because they contain both harmful liquid crystals and the valuable resource indium. However, traditional whole crush technology is difficult to realize sustainable recycling of waste LCD panels due to a challenge from the low concentrations of liquid crystals and indium. Secondary pollution inevitably occurred in recycling process. In this work, a stripping product enriched in liquid crystals and indium was first gained by a mechanical stripping separation. Then, liquid crystals were reused as carbon source in pyrolysis process to form carbon fiber in control. Carbon fiber clusters can form well under the optimal condition of 500 °C, with 30% molecular sieve (particle size < 0.3 mm) and pyrolysis time of 15 min. The pyrolysis mechanism of liquid crystals and the formation mechanism of carbon fiber were discussed. Finally, vacuum in situ reduction of indium oxide from stripping product with the prepared carbon fiber c...

Waste electronic components (ECs) recycling is a crucial part of waste printed circuit boards (WPCBs) recycling system. Waste transistors (WTs) are one of the largest obsolete ECs whose recycling technology has been poorly developed. This study presented a pyrolysis-based technology for recovering copper from WTs disassembled from WPCBs, including coarse crushing, pyrolysis, pulverizing, and sieving. First, the WTs were coarsely crushed to reduce the particle size of the epoxy molding compound (EMC). Second, the coarsely crushed WTs were pyrolyzed to damage the cross-linking network structure of EMC and reduce the hardness of EMC. Third, all of the pyrolysis residues were crushed and sieved to separate metals and nonmetals. Finally, an integrated recycling process was proposed based on above studies. In addition, the mechanism of the pyrolysis was analyzed based on bond theory and product analysis to deeply understand the recycling process. Under optimal conditions, 99.16% of copper in WTs were recovered ...

Resource recycling of millions of solid wastes is a world’s problems. Because element is the basic unit of all wastes, the essence of wastes recycling is to realize cycle of elements in wastes. In this paper, a new concept of element cycle in wastes is proposed. Under guidance of element cycle, various wastes have common connection point. The concept is clarified by a case of C, H, Cl and In element cycle from waste PVC plastic and LCD panels. In this paper, a vacuum pyrolysis of waste PVC was proposed to recycle indium in LCD and synchronously prepare carbon coating. Cl in PVC combined with In in LCD was mainly regenerated in the form of InCl3. Meantime, C and H in PVC were reused to prepare carbon coating and energy products, such as pyrolysis oil and gas. The recycling system means to change two kinds of wastes into resources by their own element characteristics. Under optimized conditions, recovery rate of indium exceeded 98 %. Meantime, with increasing temperature, microstructure of carbon coating is...

Electronic-waste recycling has become a global issue owing to its potential environmental pollution and rich metal resource. Waste multilayer ceramic capacitors (MLCCs), widely existing in discarded electronic devices, are rich in valuable metals such as silver (Ag) and palladium (Pd). However, how to effectively and in an environmentally friendly manner recycle waste MLCCs is seldom considered. This study developed an efficient and integrated process for recovering valuable materials from waste MLCCs by chloride metallurgy (CM) and corona electrostatic separation (CES). In CM, NH4Cl was used as the chlorinating agent. The results demonstrated that BaTiO3, Ag, and tin (Sn) can be chlorinated. The generated gas-phase SnCl4 was collected in the condensing zone. BaCl2 and AgCl were sequentially separated by leaching with water and sodium thiosulfate solution. The recovery efficiencies of Ag, Ba, and Sn could reach 99.21, 98.76, and 99.83%, respectively. The optimal CM parameters were considered to be 400 °C,...

Recycling e-waste has been a significant topic for environmental protection and also for resource recovery. Waste tantalum capacitors (WTCs), widely existing in discarded small appliances, are rich in high quality tantalum (Ta) resources. However, recovering Ta from WTCs is difficult due to the tightly covered mold resin. This study proposes an efficient and environmentally friendly process using supercritical water (SCW) to decompose the organics and recover Ta from WTCs. Two methods of SCW were studied: SCW depolymerization (SCWD) and SCW oxidation (SCWO). The results indicated that the mold resin (packing) of WTCs were effectively decomposed by SCW treatments. The organic decomposition efficiency in SCWD was lower than that in SCWO. The optimal parameters for SCWD and SCWO were, respectively, considered to be 425 °C, 25 MPa, and 120 min and 400 °C, 25 MPa, and 90 min, adding a 10% volume ratio of H2O2. After SCWO treatment, Ta electrodes were directly recovered, and the purity of Ta could reach 93.18%....

Due to its superior electronic properties, gallium arsenide (GaAs) is widely used in integrated circuits which are the core elements of most electric and electronic equipment. With the obsolescence of this equipment, a large amount of GaAs scraps is generated, which may possess potential threats to human beings and the environment if treated improperly. In this paper, an integrated process combining sulfurization and evaporation is proposed to recycle arsenic from GaAs scraps. The sulfides of arsenic can be easily evaporated and recycled. More importantly, the environmental requirements are satisfied because of the low toxicity of the arsenic sulfides. Using solid sulfur as the sulfurizing agent, 88.2% of arsenic can be extracted from GaAs scraps under the optimized conditions of 5 K/min heating rate, 453 K midsection temperature, 40 min midsection holding time, 1073 K final temperature, and 60 min corresponding holding time. The behavior of arsenic during the sulfurizing thermal process is discussed in d...

Waste tantalum capacitors (WTCs), dismantled from waste printed circuit boards, are considered a high quality tantalum (Ta) resource. Ta is a rare and strategic material. Nearly half of the Ta consumption is used for manufacturing tantalum capacitors. Furthermore, large amounts of energy and chemicals are consumed during the Ta purification process. Therefore, recovering Ta from WTCs can sustainably utilize the Ta resource and reduce pollution. However, the recycling technology has been poorly developed. This study proposed vacuum pyrolysis (VP) and mechanical–physical separation (MPS) to recover Ta and other materials from WTCs. First, the WTCs were treated by VP to decompose the organics. The suitable VP parameters were considered as 400 °C, 50 Pa, and 60 min. Then, the residues were performed by MPS. Consequently, nickel–iron terminals were recovered by magnetic separation. Ta and silica were separated by corona electrostatic separation. The recovery rate and purity of Ta could reach 97.02 ± 0.85% and ...

The demand for tantalum (Ta) is rapidly increasing due to the manufacture of Ta capacitors (TCs) for electronic devices. With the increasing awareness of environmental protection and conservation of rare metal Ta, recycling of Ta from waste TCs (WTCs) is becoming a hot topic in current society. In this study, an efficient and environmentally friendly process for recycling Ta from WTCs by chloride metallurgy (CM) is proposed. In the CM process, the nontoxic FeCl2 is chosen as the chlorination agent. Thermodynamic analysis demonstrates that Ta can selectively react with FeCl2, and the generated TaCl5 can be easily separated and then condensed in the condensation zone. The recovery of Ta can reach 93.56% under the optimal chlorination parameters as follows: heating temperature of 500 °C, FeCl2 addition amount of 50%, holding time for 2 h, and particle size of Ta-rich powder less than 0.24 mm. Moreover, the kinetic mechanism is discussed, and the rate-controlling step in the chlorination reaction of Ta is det...

Abundant waste toner cartridges have been generated from the use of printers. They contain aluminum, plastic, steel, and toner. Waste toner cartridges will pollute the environment if they are not properly treated. An environment-friendly recovery line of waste toner cartridges had been constructed in our previous work. Eddy current separation was employed to separate aluminum particles from plastic particles of crushed waste toner cartridges. However, hollow aluminum particles existed in crushed waste toner cartridges, and they have a rather low separation rate from plastic particles. There was little information about hollow aluminum particles in eddy current separation. For improvement of the efficiency of eddy current separation, models of eddy current force and movement behaviors of hollow aluminum particles in eddy current separation were established. In a comparison of horizontal throws of hollow aluminum particles to solid aluminum particles, we found hollow characters greatly decreased the horizon...

Due to economic and societal reasons, informal activities including open burning, backyard recycling, and landfill are still the prevailing methods used for electronic waste treatment in developing countries. Great efforts have been made, especially in China, to promote formal approaches for electronic waste management by enacting laws, developing green recycling technologies, initiating pilot programs, etc. The formal recycling process can, however, engender environmental impact and resource consumption, although information on the environmental loads and resource consumption is currently limited. To quantitatively assess the environmental impact of the processes in a formal printed wiring board (PWB) recycling chain, life cycle assessment (LCA) was applied to a formal recycling chain that includes the steps from waste liberation through materials refining. The metal leaching in the refining stage was identified as a critical process, posing most of the environmental impact in the recycling chain. Global warming potential was the most significant environmental impact category after normalization and weighting, followed by fossil abiotic depletion potential, and marine aquatic eco-toxicity potential. Scenario modeling results showed that variations in the power source and chemical reagents consumption had the greatest influence on the environmental performance. The environmental impact from transportation used for PWB collection was also evaluated. The results were further compared to conventional primary metals production processes, highlighting the environmental benefit of metal recycling from waste PWBs. Optimizing the collection mode, increasing the precious metals recovery efficiency in the beneficiation stage and decreasing the chemical reagents consumption in the refining stage by effective materials liberation and separation are proposed as potential improvement strategies to make the recycling chain more environmentally friendly. The LCA results provide environmental information for the improvement of future integrated technologies and electronic waste management.

The representative waste television recycling process was chosen as the object of this study, including manual dismantling and mechanical separation of printed circuit boards (PCBs) and cathode ray tubes (CRTs) in two independent workshops. During these recycling processes, fine particulate matter and heavy metals will be released into the air to impact the environment and the health of the workers. The mass concentrations of PM2.5 (particles below 2.5 μm diameter) in mechanical and dismantling workshops ranged from 252.6 to 290.8 μg/m(3) and from 112.7 to 169.4 μg/m(3), respectively. The average concentration of PM2.5 around the workshop was 98.5 μg/m(3). Meanwhile, the contents of PM10 (particles below 10 μm diameter) were all below the risk threshold, except that (360.4 μg/m(3)) monitored in the mechanical workshop. In two workshops, Pb (20.46 and 6.935 mg/g) was the most enriched metal in the PM2.5 samples, while in PM10, the concentration of Cu (27.76 and 31.80 mg/g) was the largest. The concentration of Cd was the least in both PM10 and PM2.5. Health risk assessment showed that the total hazard indexes for non-carcinogenic metal in PM2.5 monitored in mechanical and dismantling workshops and in the southeast of the workshops were 7.61, 3.01, and 1.57, respectively, all above the safety level. Furthermore, Pb (7.28 and 3.01) might possibly have a non-carcinogenic effect on the workers in two workshops, and the sequence of the hazard quotient (HQ) through the three exposure ways was ingestion > dermal contact > inhalation. The lifetime cancer risk of four targeted metals was Cr > Ni > Pb > Cd, which could be proven in all monitoring samples. This study aims to provide a large amount of valid data for the State Environmental Protection Department to develop relevant environmental standards and for companies to improve the waste television recycling system to be more efficiently and environmentally friendly.

Environmental information in physical recovery system of waste refrigerator cabinets was provided in this paper. The system included closed shearing, activated carbon adsorption (ACA), air current separation, magnetic separation, and eddy current separation. Exposures of CFC-11, heavy metals, and noise emitted from the system were assessed. Abundant CFC-11 (510 mg/m³) was detected in crusher cavity. However, due to the employment of ACA, little CFC-11 (9.5 mg/m³) could be detected out the recovery system. Heavy metals were detected in the air of workshop (TSP: Cu ≤ 4.91 μg/m³, Pb ≤ 3.17 μg/m³, PM10: Cu ≤ 2.1 μg/m³, Pb ≤ 1.3 μg/m³). Assessment results indicated the concentrations of heavy metals in air were safe for workers. Copper (25.8 mg/kg) and lead (19.5 mg/kg) were found in ground dust of the workshop and the concentrations were safe for soils. Noise level (98.2 dB(A)) of crushing process could cause disease and hearing impairment to workers. For controlling noise, acoustic hood was designed to reduce the noise level to 69.7 dB(A).The above information was of assistance to the industrialization of physical process for recovering waste refrigerator cabinets on environmental protection. Meanwhile, it contributed to the knowledge of environmental information of physical technology for recovering e-waste.

Electrostatic separation has been widely used to separate conductors and nonconductors for recycling e-waste. However, the components of e-waste are complex, which can be classified as conductors, semiconductors, and nonconductors according to their conducting properties. In this work, we made a novel attempt to recover the mixtures containing conductors (copper), semiconductors (extrinsic silicon), and nonconductors (woven glass reinforced resin) by electrostatic separation. The results of binary mixtures separation show that the separation of conductor and nonconductor, semiconductor and nonconductor need a higher voltage level while the separation of conductor and semiconductor needs a higher roll speed. Furthermore, the semiconductor separation efficiency is more sensitive to the high voltage level and the roll speed than the conductor separation efficiency. An integrated process was proposed for the multiple mixtures separation. The separation efficiency of conductors and semiconductors can reach 82.5% and 88%, respectively. This study contributes to the efficient recycling of valuable resources from e-waste.

Separation efficiency of eddy current separation (ECS) is low (about 85%) in industrial application for recovering aluminum from crushed waste toner cartridges. Influencing factors of ECS were studied to improve the separation efficiency. Operation factors were researched by orthogonal experiment of ECS on investigating the separation distance between aluminum and plastic flakes. The results indicated the difference (ωR-v) between feeding speed (v) and rotation speed (ω) of magnetic drum (radius: R) was critical factor of influencing the separation efficiency, feeding speed (v) was general factor, and collecting position (H) was subordinate factor. Separation efficiency decreased as the increasing of v, and increased as the increasing of (ωR-v). 0.9 m was the optimal value of H in the orthogonal experiment. Influencing factors of particle characteristics and machine structure were studied by newly established models for computing the separation distance between aluminum and plastic flake in ECS. The results indicated changing of particle size would influence the separation efficiency greater than ω and particle shape. Separation efficiency will increase as the increasing of particle size and ω. Shape of circle is beneficial to improve separation efficiency. Finally, approaches to improve separation efficiency of ECS were presented.

This study focused on the volatile organic compounds (VOCs) and metal leaching from three kinds of composite products made from fiberglass-resin portion (FRP) of crushed printed circuit board (PCB) waste, including phenolic molding compound (PMC), wood plastic composite (WPC), and nonmetallic plate (NMP). Released VOCs from the composite products were quantified by air sampling on adsorbent followed by thermal desorption and GC-MS analysis. The results showed that VOCs emitted from composite products originated from the added organic components during manufacturing process. Phenol in PMC panels came primarily from phenolic resin, and the airborne concentration of phenol emitted from PMC product was 59.4 ± 6.1 μg/m(3), which was lower than odor threshold of 100% response for phenol (180 μg/m(3)). VOCs from WPC product mainly originated from wood flour, e.g., benzaldehyde, octanal, and d-limonene were emitted in relatively low concentrations. For VOCs emitted from NMP product, the airborne concentration of styrene was the highest (633 ± 67 μg/m(3)). Leaching characteristics of metal ions from composite products were tested using acetic acid buffer solution and sulphuric acid and nitric acid solution. Then the metal concentrations in the leachates were tested by ICP-AES. The results showed that only the concentration of Cu (average = 893 mg/L; limit = 100 mg/L) in the leachate solution of the FRP using acetic acid buffer solution exceeded the standard limit. However, concentrations of other metal ions (Pb, Cd, Cr, Ba, and Ni) were within the standard limit. All the results indicated that the FRP in composite products was not a major concern in terms of environmental assessment based upon VOCs tests and leaching characteristics.