Degradation and regeneration inhibition of PCDD/Fs in incineration fly ash by low-temperature thermal technology.

Low-temperature thermal degradation of PCDD/Fs for incineration fly ash (IFA), as a novel and emerging technology approach, offers promising features of high degradation efficiency and low energy consumption, presenting enormous potential for application in IFA resource utilization processes. This review summarizes the concentrations, congener distributions, and heterogeneity characteristics of PCDD/Fs in IFA from municipal, medical, and hazardous waste incineration. A comparative analysis of five PCDD/Fs degradation technologies is conducted regarding their characteristics, industrial potential, and applicability. From the perspective of low-temperature degradation mechanisms, pathways to enhance PCDD/Fs degradation efficiency and inhibit their regeneration reactions are discussed in detail. Finally, the challenges to achieve low-temperature degradation of PCDD/Fs for IFA with high-efficiency are prospected. This review seeks to explore new opportunities for the detoxification and resource utilization of IFA by implementing more efficient and viable low-temperature degradation technologies.

Defluorination and directional conversion to light fuel by lithium synergistic vacuum catalytic co-pyrolysis for electrolyte and polyvinylidene fluoride in spent lithium-ion batteries.

To overcome the drawbacks of current recycling technologies and achieve clean utilization of toxic substances in spent lithium-ion batteries, a lithium synergistic vacuum catalytic co-pyrolysis method was proposed to defluorinate electrolyte and polyvinylidene fluoride with directional conversion to light fuel. The gas chromatography-mass spectrometry results indicated, compared to the control group, that adding CaO-ZSM-5 catalyst increased the light fuel (alcohols and hydrocarbons) content of the pyrolysis gas from 61.8 % to 91.47 % under the optimal conditions (530 °C and initial pressure of 100 Pa), whereas the total proportion of esters and toxic organic compounds decreased from 32.58 % to 3.99 %. Moreover, the ethylene carbonate and hexanedinitrile content of the electrolyte was enriched to 85 % in the pyrolysis oil. Notably, fluoride was not detected in the pyrolysis oil and gas, achieving a 98.16 % defluorination rate, implying that hazardous waste was transformed to ordinary waste, thereby greatly avoiding toxic emissions to the environment. The X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray spectroscopy data indicated that fluorine was fixed in the form of CaF2. X-ray photoelectron spectroscopy and XRD analysis of the catalytic pyrolysis residue confirmed that nonferrous metals in the cathode material were converted into simple substances and oxides. Finally, possible co-pyrolysis mechanisms of the organic compounds are proposed, including Li+ generation, chain initiation, catalytic pyrolysis, and directional conversion.

The Foreseeable Future of Spent Lithium-Ion Batteries: Advanced Upcycling for Toxic Electrolyte, Cathode, and Anode from Environmental and Technological Perspectives.

With the rise of the new energy vehicle industry represented by Tesla and BYD, the need for lithium-ion batteries (LIBs) grows rapidly. However, owing to the limited service life of LIBs, the large-scale retirement tide of LIBs has come. The recycling of spent LIBs has become an inevitable trend of resource recovery, environmental protection, and social demand. The low added value recovery of previous LIBs mostly used traditional metal extraction, which caused environmental damage and had high cost. Beyond metal extraction, the upcycling of spent LIBs came into being. In this work, we have outlined and particularly focus on sustainable upcycling technologies of toxic electrolyte, cathode, and anode from spent LIBs. For electrolyte, whether electrolyte extraction or decomposition, restoring the original electrolyte components or decomposing them into low-carbon energy conversion is the goal of electrolyte upcycling. Direct regeneration and preparation of advanced materials are the best strategies for cathodic upcycling with the advantages of cost and energy consumption, but challenges remain in industrial practice. The regeneration of advanced graphite-based materials and battery-grade graphite shows us the prospect of regeneration of anode. Furthermore, the challenges and future development of spent LIBs upcycling are summarized and discussed from technological and environmental perspectives.

Safety of high-carbohydrate fluid diet 2 h versus overnight fasting before non-emergency endoscopic retrograde cholangiopancreatography: A single-blind, multicenter, randomized controlled trial.

BACKGROUND: Although overnight fasting is recommended prior to endoscopic retrograde cholangiopancreatography (ERCP), the benefits and safety of high-carbohydrate fluid diet (CFD) intake 2 h before ERCP remain unclear. This study aimed to analyze whether high-CFD intake 2 h before ERCP can be safe and accelerate patients' recovery. METHODS: This prospective, multicenter, randomized controlled trial involved 15 tertiary ERCP centers. A total of 1330 patients were randomized into CFD group (n = 665) and fasting group (n = 665). The CFD group received 400 mL of maltodextrin orally 2 h before ERCP, while the control group abstained from food/water overnight (>6 h) before ERCP. All ERCP procedures were performed using deep sedation with intravenous propofol. The investigators were blinded but not the patients. The primary outcomes included postoperative fatigue and abdominal pain score, and the secondary outcomes included complications and changes in metabolic indicators. The outcomes were analyzed according to a modified intention-to-treat principle. RESULTS: The post-ERCP fatigue scores were significantly lower at 4 h (4.1 ± 2.6 vs. 4.8 ± 2.8, t = 4.23, P <0.001) and 20 h (2.4 ± 2.1 vs. 3.4 ± 2.4, t = 7.94, P <0.001) in the CFD group, with least-squares mean differences of 0.48 (95% confidence interval [CI]: 0.26-0.71, P <0.001) and 0.76 (95% CI: 0.57-0.95, P <0.001), respectively. The 4-h pain scores (2.1 ± 1.7 vs. 2.2 ± 1.7, t = 2.60, P = 0.009, with a least-squares mean difference of 0.21 [95% CI: 0.05-0.37]) and positive urine ketone levels (7.7% [39/509] vs. 15.4% [82/533], χ2 = 15.13, P <0.001) were lower in the CFD group. The CFD group had significantly less cholangitis (2.1% [13/634] vs. 4.0% [26/658], χ2 = 3.99, P = 0.046) but not pancreatitis (5.5% [35/634] vs. 6.5% [43/658], χ2 = 0.59, P = 0.444). Subgroup analysis revealed that CFD reduced the incidence of complications in patients with native papilla (odds ratio [OR]: 0.61, 95% CI: 0.39-0.95, P = 0.028) in the multivariable models. CONCLUSION: Ingesting 400 mL of CFD 2 h before ERCP is safe, with a reduction in post-ERCP fatigue, abdominal pain, and cholangitis during recovery. TRAIL REGISTRATION: ClinicalTrials.gov, No. NCT03075280.

Monitoring the Resources and Environmental Impacts from the Precise Disassembly of E-Waste in China.

Due to the dispersed distribution of e-waste and crude disassembly in traditional recycling, valuable metals are not traceable during their life cycle. Meanwhile, incomplete separation between metals and nonmetals reduces the economic value of disassembled parts, which leads to higher environmental costs for metal refining. Therefore, this study proposes a precise disassembly of e-waste to finely classify and recover metals in an environmentally friendly way. First, the macroscopic material flow of e-waste in China (source, flow, scrap, and recycling gap) was measured based on data collected by the government and 109 formal recycling enterprises. The sustainable recycling balance time points for e-waste recycling and scrap volumes were forecast by introducing an additional recycling efficiency. By 2030, the total scrap volume of e-waste is predicted to reach 133.06 million units. For precise disassembly, the main metals and their percentages from these typical e-wastes were measured based on material flow analysis combined with experimental methods. After precise disassembly, the proportion of reusable metals increases significantly. The CO2 emission of precise disassembly with the smelting process was the lowest compared with crude disassembly with smelting and ore metallurgy. The greenhouse gas for secondary metals Fe, Cu, and Al was 830.32, 1151.62, and 716.6 kg CO2/t metal, respectively. The precise disassembly of e-waste is meaningful for building a future resource sustainable society and for carbon emission reduction.

Detachable string magnetically controlled capsule endoscopy for detecting high-risk varices in compensated advanced chronic liver disease (CHESS1801): A prospective multicenter study.

BACKGROUND: Gastroesophageal varices is a serious complication of compensated advanced chronic liver disease (cACLD). Primary prophylaxis to reduce the risk of variceal hemorrhage is recommended if high-risk varices (HRV) are detected. We performed this study to compare the accuracy, patients' satisfaction and safety of detection of HRV by detachable string magnetically controlled capsule endoscopy (DS-MCCE) with esophagogastroduodenoscopy (EGD) as the reference. METHODS: We prospectively recruited participants with cACLD from 12 university hospitals (11 in China and one in the United Kingdom) between November 2018 and December 2019 (ClinicalTrials.gov, NCT03749954). All participants underwent DS-MCCE, followed by EGD within a week in a blinded fashion. Following endoscopy, and on the same day, participants were asked to fill in a satisfaction questionnaire regarding their experience. FINDINGS: A total of 105 eligible participants were enrolled. With EGD as the reference standard, the concordance index, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of DS-MCCE in diagnosis of HRV were 0•90 (95% confidence interval [CI]: 0•83-0•95), 92% (95% CI: 78-98%), 88% (95% CI: 78-95%), 80% (95% CI: 70-92%), 95% (95% CI: 90-100%), 7•91 (95% CI: 4•10-15•30), and 0•09 (95% CI: 0•03-0•30), respectively. The kappa score of 0•78 (95% CI: 0•65-0•90) suggested substantial agreement between DS-MCCE and EGD. Moreover, in participants undergoing EGD without sedation, the satisfaction of DS-MCCE was significantly better than that of EGD (p < 0•0001, d = 1•15 [95%CI: 0•88-1•42]). All participants confirmed the excretion of the capsule, and no adverse events occurred. INTERPRETATION: DS-MCCE is an accurate alternative to EGD for detecting HRV in cACLD, which is safe and associated with better satisfaction. FUNDING: A full list of funding can be found in the Funding Support section.

Renewable redox couple system for sustainable precious metal recycling from e-waste via halide-regulated potential inversion.

Precious metal (PM) retrievement from e-waste is of great significance for reducing virgin mining activity and promoting rare resource sustainability. However, current PM recycling methods rely mainly on caustic aqua regia or unstable sulfur-based ligand, which has caused severe environmental damage and process inefficiency. Here, we propose an environmentally friendly halide-regulated strategy, utilizing milder and renewable oxidant-cupric/ferric ion for facile PM dissolution. This is realized by the synergistic effect of enhanced oxidizing ability of Cu(II) and reduced oxidation potential of PM with halide addition. Electrochemical tests and leaching experiment results show that Cu(II)/Cu(I) redox potential experiences great change with bromide, increasing from 0.4 to 0.75 V. Fast corrosion feature was observed for Au in Cu(II)/Fe(III)-Br- and Pd in Cu(II)/Fe(III)-Cl-, and it can be accelerated by increasing oxidant and halide concentration. Our proposed strategy outperforms traditional methods with stable and fast dissolution, where 2.5 mol/L Br- is appropriate for Au dissolution. Moreover, selective dissolution of base metal, Pd/Ag, and Au can be achieved via ligand alteration and be further combined with electrodeposition technique for multi metal recovery and oxidant regeneration. This halide-regulated strategy can lead PM recycling from pollutive status towards environmentally friendly road.

Novel Electrodeposition Method for Cu-In-Cd-Ga Sequential Separation from Waste Solar Cell: Mechanism, Application, and Environmental Impact Assessment.

While CIGS solar cell has been experiencing an expanded photovoltaic market and increasing research interest in cell design, its treatment after obsoletion remains an upcoming issue. The heavy metals involved, such as Cd, can threat the environment, while strategic resources, such as rare metals In and Ga, offer a great recycling oppotunity. However, due to its multimetal feature, traditional recycling methodology shows poor separation-extraction efficiency and additional environmental burdens with intense reagent consumption and waste generation. Here, we report a sequential electrodeposition method for pure metal recycling from this Cu-In-Cd-Ga quaternary system in a more environmentally friendly and efficient manner. Stability constant-corrected redox potential supplemented with metal electroreduction tests predicts well the potential window for sequential electrodeposition. Cu and In electrodeposition shows 100% separation with high Coulombic efficiency (>80%), whereas Ga electrodeposition presents slower kinetics and performs better at a pH of 2.5. Environmental impact assessment indicates that the proposed recycling route allows remarkable reduction of global warming and toxicity impacts compared with metal production from virgin mining and reference processes. We further unveiled the applicability of the electrodeposition technique in the context of anthropogenic mineral recycling, emphasizing resource sustainability and cleaner production.

Facile indium recovery from waste liquid crystal displays: Chloride-facilitated indium electroreduction and stepwise Cu/MoO2 and indium electrodeposition.

With a huge amount of waste liquid crystal displays (LCDs) generated annually, their proper recycling raises continuous concern to realize pollution control (heavy metal and liquid crystal) and resource recovery (indium). However, due to their multi-metal feature, traditional hydrometallurgy lacks of sufficient selectivity, which makes the recycling route lengthy, costly, and generate more waste. Electrodeposition acts as a promising technique for selective metal extraction from multi-metal system due to its high selectivity and electron as clean reagent. To fully develop its application in metal recovery, stepwise Cu/MoO2 and In electrodeposition from In-Cu-Mo-Fe waste LCD leachate is explored in depth. Electrochemical behavior analysis shows Cu and MoO2 can be first electrodeposited for their higher electroreduction potential. Cl- plays a key role in accelerating indium electroreduction kinetics, which largely shortens the extraction time without the sacrifice of current efficiency. This accelerating effect is attributed to the increased concentration of electroactive species or collision frequency. Under optimized condition, 99.41% of indium (> 99% purity) can be electrodeposited within 13 h with high current efficiency. This study provides a cleaner approach for waste LCDs recycling and gives implications for the potential application of electrochemical technique in e-waste recycling.

Arsenic Removal and Recovery of Germanium and Tungsten in Toxic Coal Fly Ash from Lignite by Vacuum Distillation with a Sulfurizing Reagent.

Every year, billions of tons of lignite are burnt to generate electricity, meanwhile generating large amounts of coal fly ash (CFA) that is regarded as an industrial waste. During lignite combustion, arsenic and scarce metals are simultaneously volatilized in the form of oxide into CFA. This study proposed an effective vacuum distillation method to remove As and recover Ge and W from CFA. The feasibility of separating As and recycling Ge and W from CFA was verified by the theoretical analysis. The experimental result indicated that the removal ratio of As was 96 ± 1% and the contents of Ge and W reached 0.75 ± 0.023 and 0.24 ± 0.016 wt % in the residue, which were enriched 17.2 and 1.2 times, respectively, at a temperature of 550 °C, with 50 wt % sulfurizing agent added under pressure of 1 Pa and 240 min of heating. For the condensed product, chemical species As2S3 and As4S4 were detected by X-ray photoelectron spectroscopy analysis. For Ge and W in the residue, GeOx (x < 2), GeS, WOx (x < 3), and WS2 were the main chemical species. The potential mechanism involved in the release of arsenic from CFA, vacuum sulfurization, evaporation, and condensation was proposed. The kinetic analysis indicated that the apparent activation energy (Eα) was 31.24 kJ mol-1. Those results encourage further exploration of vacuum separation technology to environmentally friendly recycle CFA.

Process simulation of Ohno continuous casting for single crystal copper prepared from scrap copper in waste printed circuit boards.

How to realize the high value-added utilization of scrap copper from e-waste is a meaningful topic. In the study, an Ohno Continuous Casting (OCC) process is an existing method you applied to purify the copper. Based onthe model of diffusion-controlled grain growth kinetics, the redistribution of impurity of tin in the scrap copper were studied under the different continuous casting speed and mold temperature. On the centerline, macrosegregation in the axial direction of the tin was more obvious with the decrease of continuous casting speed. The small continuous casting rate was beneficial to the segregation and enrichment of tin. The axial segregation gradually decreased with the increase of the mold temperature. The flattening of the liquid-solid interface resulted in a weakening of the solute enrichment at the root of the interface with the increase of temperature. Morphology, electron backscattered diffraction (EBSD) analysis showed the structure of single crystal copper. The range of resistance of single crystal copper was from 5 × 10-6 to 3 × 10-5 Ω m. Obviously, the resistance of the single crystal copper was significantly smaller than that of ordinary copper wire (9.0 × 10-3 Ω m). This study provided a key theoretical and practical basis for the high value-added reuse of copper in e-waste.

Separation of metals from Ni-Cu-Ag-Pd-Bi-Sn multi-metal system of e-waste by leaching and stepwise potential-controlled electrodeposition.

Electronic waste, as hazardous waste, contains a large amount of metals, which is of great recovery value. However, they are difficult to separate due to wide variety and complex distribution. Most of current recycling methods are environmentally-unfriendly or complicated. In this study, a simple, efficient and green approach for metals separation from Ni-Cu-Ag-Pd-Bi-Sn multi-metal system of e-waste was proposed combining mild leaching and stepwise potential-controlled electrodeposition. The leaching efficiencies of Ni, Ag, Pd, Cu and Bi were 99.16%, 99.09%, 94.91%, 99.61% and 23.76% with 1 mol/L HNO3 at 80 °C. The leaching process was analyzed. It showed that the existence of Ag-Pd continuous solid solution in the alloy lowered the oxidation potential of Pd, which facilitated its leaching. Sn precipitated as SnO2. Then Ag-Pd alloy and Cu-Bi alloy were separately extracted from the leaching solution by stepwise electrodeposition. 97.72% of Ag and 98.05% of Pd were recycled after 5 h with potential of 0.35 V. The recovery efficiencies of Cu and Bi were 97.87% and 97.33% after 7 h with potential of 0.05 V. The EDS results showed high purity property of Ag-Pd and Cu-Bi alloy. This process can achieve cleaner and efficient extraction of metals from multi-metal system in e-waste.

Selective electrochemical extraction of copper from multi-metal e-waste leaching solution and its enhanced recovery mechanism.

Recycling activity for waste electrical and electronic equipment is always accompanied with leaching solution containing copper. Its selective extraction is of environmental and economic significance, and is beneficial for subsequent resource purification procedure. Compared with techniques such as chemical precipitation and solvent extraction, potentiostatic electrodeposition is outstanding with the advantage of high selectivity, electron as clean reagent, and minimal chemical usage. However, key factors affecting copper electrodeposition behavior as well as its kinetic process remain unclear, which blocks its further application. In this study, selective copper electrochemical extraction from multi-metal leaching solution of waste liquid crystal display panels is explored. Copper electrodeposition is analyzed from electrochemical and mass transport point of view, and the main results are summarized: (i) copper can be first electrodeposited due to its higher reduction potential compared with indium; (ii) applied potential and agitation are the most influential factors towards space-time yield and current efficiency; (iii) a semi-empirical kinetic model could quantitatively describe the influence of agitation and the time-current-concentration relationship. The model-predicted extraction rate agreed well with experimental data throughout electrodeposition; (iv) electrodeposition experiments show over 95% of copper can be selectively extracted as ultrafine copper powder (~150 nm) at 0.05 V (vs. SHE).

An integrated capture of copper scrap and electrodeposition process to enrich and prepare pure palladium for recycling of spent catalyst from automobile.

The coordinated treatment for two kinds of waste is an effective way to save energy and improve the recovery efficiency of resource. In worldwide, more than half of palladium is used to produce catalysts in automobile. However, with the increasing consumption of palladium, the scarcity of palladium resource is becoming prominent. This paper proposed an integrated process based on capture of copper scrap and electrodeposition process to recycle palladium in spent catalysis from automobile. The technological process mainly consisted of two procedures: capture of copper scrap with the purposes of enriching palladium and electrodeposition process with the purposes of separating and purifying palladium. Several highlights were summarized as follows: (i) a capture mechanism of palladium by copper scrap was studied by the calculation of surface thermodynamics and first principles. (ii) Optimum designs, parameter and product analysis were developed to guide industrial recycling. The appropriate parameters for capture of copper scrap are the melting temperature reached 1400 °C, adding 20% dosage of copper scrap and 2 of mass ratio of SiO2/Al2O3 and for the electrodeposition process, nearly 100% of palladium was deposited on the cathode under 0.1 M concentration of HNO3, -0.042 V of electrodeposition potential and 25 °C reaction temperature with 9 h. (iii) This process overcame the shortages of traditional process and showed its efficiency and environmental performance. This study is significant for high-efficient, low-cost and environment-friendly recycling of valuable resource in spent catalysis from automobile.

A quickly, effectively screening process of novel corona virus disease 2019 (COVID-19) in children in Shanghai, China.

BACKGROUND: A recent cluster of pneumonia cases in China was caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report the screening and diagnosis of corona virus disease 2019 (COVID-19) in our hospital. METHODS: Developed a procedure for the identification of children cases with COVID-19 in outpatient and emergency department of our hospital, then we observed how this process works. RESULTS: (I) There were 56 cases considered suspected cases, and 10 cases were confirmed as COVID-19. (II) Of the 10 confirmed COVID-19 cases admitted in our hospital, 5 were males and 5 were females, aged from 7 months to 11 years, the average age is 6.0±4.2 years, 6 cases were mild pneumonia, the others were upper respiratory tract infection. (III) We followed up 68 patients in isolation at home until symptoms disappeared. Non were missed in the patient's first visit. The sensitivity of this method is 100% and the specificity is 71.3%. CONCLUSIONS: Our screening process works well, and it is also necessary to establish a screening network in the hospital.

Recovery of palladium and silver from waste multilayer ceramic capacitors by eutectic capture process of copper and mechanism analysis.

Recycling waste multilayer ceramic capacitors (MLCCs) is significant for environmental protection and resource recovery, which contain rich precious metals including palladium and silver. The existing recycling methods have many shortcomings such as environmental pollution, low recovery efficiency and low purity of precious metals. In view of the special structure of MLCCs and low content of precious metals per unit mass, a novel approach of enrichment for recovering palladium and silver from waste MLCCs by eutectic capture process of copper was proposed, in which process precious metals were separated and enriched for subsequent recovery. The recovery rates of palladium and silver reached 100 % and 87.53 %, respectively under the optimal condition. And the enrichment multiples of palladium and silver were 13.16 and 7.37. The Cu-Pd-Ag alloy was formed in the capture process, of which palladium and copper formed Cu-Pd solid solution, while silver was a separate phase through the analysis of SEM-EDS, XPS and XRD. Besides, the molten residue can be reused to prepare glass-ceramics. Finally, the mechanism was analyzed through thermodynamics, which was divided into two processes: migration of precious metals and alloy formation. This study provides a highly efficient and environmentally friendly method for recycling precious metals from waste MLCCs.

Selective recovery of lead and zinc through controlling cathodic potential in a bioelectrochemically-assisted electrodeposition system.

Proper treatment of mining wastewaters is critically important to minimize contamination by heavy metals contained in those wastewaters. Herein, a bioelectrochemically-assisted electrodeposition (BES-EDP) system was developed and investigated for selective removal and recovery of Pb and Zn from a mimicked smelting wastewater. It was observed that those two metals were reduced at different cathodic potentials and electrodeposition time. At a cathodic potential of -0.75 V vs. Ag/AgCl, 98.5 ± 1.4 % of Pb was recovered after 10 h of reaction while there was little Zn deposition. Increasing the cathodic potential to -1.2 V could achieve 98.7 ± 0.7 % of Zn with the electrodeposition time of 6 h. The composition of the deposits confirmed the results from solution analysis and metal oxides were also formed during metal reduction. The diffusion impedance was much higher than the charge transfer resistance, suggesting that the diffusion process was a rate limiting step for electrodeposition. The diffusion process was verified by chronoamperometry with a good fit in Cottrell equation. The electrodeposition equilibrium constant k0 was determined as 3.76 cm s-1. Those results have demonstrated the feasibility of using bioelectricity to assist with selective metal recovery and warrant further investigation of technologies for sustainable management of mining wastewaters.

Indium recovery from In-Sn-Cu-Al mixed system of waste liquid crystal display panels via acid leaching and two-step electrodeposition.

Since indium (In) was the most valuable resource in waste liquid crystal panels (LCDs), most researches only focused on preliminary recovery of In, while those coexisting metal elements (Cu, Sn, Al) raised little concern. This could lead to waste of resources, potential risk of heavy metal pollution, and also complexation of following In purification procedures. Besides, current hydrometallurgy processes for In purification are complicated, consume more reagents and generate more wastewater. Therefore, this research applied simple acid leaching and two-step electrodeposition for In-Sn and In-Cu-Al separation with minimum waste generation and input. Considering the special doping structure of indium-tin oxide (ITO), feasibility for concurrent In leaching and Sn precipitation was explored based on the unique Sn species' dissolution and precipitation behavior during acid leaching. Since the behavior of Sn was more sensitive to acidity and temperature, 97.07% of Sn removal and 99.25% of In recovery could be achieved using 1 mol/L H2SO4 at 70 ℃ for 1 h. A specific kinetic model depicting In leaching in thin ITO film situation was developed referring to avrami equation. Then, the application of two-step electrodeposition enabled 95.32% extraction of Cu and deposition of In with a purity over 99 wt% at respective potential.

Towards minimization of secondary wastes: Element recycling to achieve future complete resource recycling of electronic wastes.

Recycling resources from millions of tons of e-wastes are a global challenge. E-wastes is complex and contains both toxic organics and valuable metals. Therefore, the technologies for e-wastes recycling are totally different from those used for mineral separation. Current technologies for e-wastes tend to focus on recycling materials with high economic value and ignore components that cannot be recycled or have low reuse value. As a result, some secondary pollution problems inevitably occur due to the recycling process. Based on these problems, we summarize the universal characteristics of e-wastes and explore new approaches to achieve complete resource recycling of e-wastes with minimum secondary waste generation. A concept of element recycling is proposed to achieve complete resource recycling of e-wastes in the study. We can use the properties of the elements in different types of e-wastes to achieve e-wastes recycling, i.e., recycle of elements in e-wastes. Under the guidance of element recycling, various e-wastes types have common connections. If element recycling in e-wastes is realized, all components in e-wastes can be fully recycled without/with minimal production of secondary waste. The two case studies are discussed to clarify the concept and principle of element recycling. This study explores the recycling of e-wastes from a new perspective-element recycling in e-wastes. The concept of element recycling is significant for resource recycling from e-wastes.

Tracking and quantifying the cobalt flows in mainland China during 1994-2016: Insights into use, trade and prospective demand.

In recent years, the demand for cobalt is increasing dramatically because of its critical role in clean energy technologies globally. China has been a leading consumer and refiner of cobalt, and meanwhile is a scarce country of cobalt resources. Its growing domestic demand may impose significant pressure on sustainable development of cobalt resources and make it potentially vulnerable to supply shortages. Aiming at identifying the potential opportunities for improving cobalt resource efficiency and supply security, dynamic stocks and flows analysis was applied to track and quantify the anthropogenic cobalt cycles in mainland China such as its production, use, and trade over the years 1994-2016. The analysis results showed that the production, trade and consumption of cobalt resources in mainland China grew significantly in the past two decades. China has been a net importer of cobalt raw materials but a net exporter of cobalt chemicals and final cobalt-containing products, indicating that China is bearing increasing environmental burden of processing cobalt product for other economies. The in-use stock of cobalt has reached over 140,000 t by 2016, of which the cobalt contained in in-use batteries accounted for approximately 77%. The recycling rate of end-of-life (Eol) products kept at a very low level, less than 20% in the past decades. The cumulative domestic demand of cobalt is projected to exceed China's reserve base by around 2022 based on scenario analysis. Furthermore, some recommendations were proposed for the sustainable development of China's cobalt resource, including the improvement of national cobalt reserve system, development of diversified resource supply channel and the establishment of a recycling system and associated regulations for cobalt-containing obsolete products.