Jinhui Li

Characterization and Inventory of PCDD/Fs and PBDD/Fs Emissions from the Incineration of Waste Printed Circuit Board

Many developing countries have not significantly changed their course with regard to electronic waste contamination, and they are still facing the specter of mountains of hazardous electronic waste, with serious consequences for both the environment and public health. An efficient and stable analytical method was developed to determine the inventory and emission factors of polybrominated dibenzo-p-dioxin and dibenzofurans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) formed from the incineration of scrap printed circuit boards (PCBs). Both PBDD/Fs and PCDD/Fs have been found in all experimental sections with a maximum formation rate at temperatures between 250 and 400 °C. The amounts tended first to increase and then began to decrease as the temperature rose. When subjected to a heating temperature of 325 °C, the total content of twelve 2,3,7,8-substituted PBDD/Fs congeners (tetra- through octabromo-) gathered from three outputs was the largest, at 19u2009000, 160u2009000, and 57 ng TEQ/kg in solid, liquid, and gaseous fractions, respectively; the total content of seventeen 2,3,7,8-substituted PCDD/Fs congeners (tetra- through octachloro-) was 820, 550, and 1.4 ng TEQ/kg. The formation of PCDD/Fs was remarkably less than that of PBDD/Fs because bromine concentrations considerably exceeded chlorine concentrations. The ingredients and conditions necessary to form PCDD/Fs or PBDD/Fs were definitely present, such as products of incomplete combustion, halogenides, an oxidizing atmosphere, and a catalyst-Cu salts being the most effective, significantly increasing the yields of PCDD/Fs and PBDD/Fs and decreasing the optimum temperature range.

Examining the technology acceptance for dismantling of waste printed circuit boards in light of recycling and environmental concerns.

The dismantling of printed circuit board assemblies (PCBAs) and the recovery of their useful materials can lead to serious environmental impacts mainly due to their complicated physical structure and the variety of toxic elements contained in their material composition. So far, less attention has been paid to their responsible recycling compared to that of bare printed circuit boards. Combined with other materials recovery process, proper dismantling of PCBAs is beneficial to conserve scarce resources, reuse the components, and eliminate or safely dispose of hazardous materials. In analyzing the generation, resources potential and hazardous risk of scrap PCBAs, technologies used for the dismantling of waste PCBAs have been widely investigated and reviewed from the aspects of both industrial application and laboratory-scale studies. In addition, the feasibility of PCBA dismantling has been discussed, the determinants of which, including the heating conditions and mechanical properties have been identified. Moreover, this paper evaluates the environmental consequences caused by the dismantling of PCBAs.

A systematic review of the human body burden of e-waste exposure in China.

As China is one of the countries facing the most serious pollution and human exposure effects of e-waste in the world, much of the population there is exposed to potentially hazardous substances due to informal e-waste recycling processes. This report reviews recent studies on human exposure to e-waste in China, with particular focus on exposure routes (e.g. dietary intake, inhalation, and soil/dust ingestion) and human body burden markers (e.g. placenta, umbilical cord blood, breast milk, blood, hair, and urine) and assesses the evidence for the association between such e-waste exposure and the human body burden in China. The results suggest that residents in the e-waste exposure areas, located mainly in the three traditional e-waste recycling sites (Taizhou, Guiyu, and Qingyuan), are faced with a potential higher daily intake of these pollutants than residents in the control areas, especially via food ingestion. Moreover, pollutants (PBBs, PBDEs, PCBs, PCDD/Fs, and heavy metals) from the e-waste recycling processes were all detectable in the tissue samples at high levels, showing that they had entered residents bodies through the environment and dietary exposure. Children and neonates are the groups most sensitive to the human body effects of e-waste exposure. We also recorded plausible outcomes associated with exposure to e-waste, including 7 types of human body burden. Although the data suggest that exposure to e-waste is harmful to health, better designed epidemiological investigations in vulnerable populations, especially neonates and children, are needed to confirm these associations.

control-Alt-Delete: Rebooting Solutions for the E-Waste Problem

A number of efforts have been launched to solve the global electronic waste (e-waste) problem. The efficiency of e-waste recycling is subject to variable national legislation, technical capacity, consumer participation, and even detoxification. E-waste management activities result in procedural irregularities and risk disparities across national boundaries. We review these variables to reveal opportunities for research and policy to reduce the risks from accumulating e-waste and ineffective recycling. Full regulation and consumer participation should be controlled and reinforced to improve local e-waste system. Aiming at standardizing best practice, we alter and identify modular recycling process and infrastructure in eco-industrial parks that will be expectantly effective in countries and regions to handle the similar e-waste stream. Toxicity can be deleted through material substitution and detoxification during the life cycle of electronics. Based on the idea of Control-Alt-Delete, four patterns of the way forward for global e-waste recycling are proposed to meet a variety of local situations.

Novel approach to recover cobalt and lithium from spent lithium-ion battery using oxalic acid

With the booming of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion battery (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated spent LIBs should be recovered urgently. However, the conventional process combined with leaching, precipitating, and filtering was quite complicated to recover cobalt and lithium from spent LIBs. In this work, we developed a novel recovery process, only combined with oxalic acid leaching and filtering. When the optimal parameters for leaching process is controlled at 150 min retention time, 95 °C heating temperature, 15 g L(-1) solid-liquid ratio, and 400 rpm rotation rate, the recovery rate of lithium and cobalt from spent LIBs can reach about 98% and 97%, respectively. Additionally, we also tentatively discovered the leaching mechanism of lithium cobalt oxide (LiCoO2) using oxalic acid, and the leaching order of the sampling LiCoO2 of spent LIBs. All the obtained results can contribute to a short-cut and high-efficiency process of spent LIBs recycling toward a sound closed-loop cycle.

Innovated Application of Mechanical Activation To Separate Lead from Scrap Cathode Ray Tube Funnel Glass

The disposal of scrap cathode ray tube (CRT) funnel glass has become a global environmental problem due to the rapid shrinkage of new CRT monitor demand, which greatly reduces the reuse for remanufacturing. To detoxificate CRT funnel glass by lead recovery with traditional metallurgical methods, mechanical activation by ball milling was introduced to pretreat the funnel glass. As a result, substantial physicochemical changes have been observed after mechanical activation including chemical breakage and defects formation in glass inner structure. These changes contribute to the easy dissolution of the activated sample in solution. High yield of 92.5% of lead from activated CRT funnel glass by diluted nitric acid leaching and successful formation of lead sulfide by sulfur sulfidization in water have also been achieved. All the results indicate that the application of mechanical activation on recovering lead from CRT funnel glass is efficient and promising, which is also probably appropriate to detoxificate any other kind of leaded glass.

Environmental effects of heavy metals derived from the e-waste recycling activities in China: a systematic review.

As the worlds leading manufacturing country, China has become the largest dumping ground for e-waste, resulting in serious pollution of heavy metals in China. This study reviews recent studies on environmental effects of heavy metals from the e-waste recycling sites in China, especially Taizhou, Guiyu, and Longtang. The intensive uncontrolled processing of e-waste in China has resulted in the release of large amounts of heavy metals in the local environment, and caused high concentrations of metals to be present in the surrounding air, dust, soils, sediments and plants. Though the pollution of many heavy metals was investigated in the relevant researches, the four kinds of heavy metals (Cu, Pb, Cd and Cr) from e-waste recycling processes attracted more attention. The exceedance of various national and international standards imposed negative effects to the environment, which made the local residents face with the serious heavy metal exposure. In order to protect the environment and human health, there is an urgent need to control and monitor the informal e-waste recycling operations.

Recycling Metals from Wastes: A Novel Application of Mechanochemistry

Recycling metals from wastes is essential to a resource-efficient economy, and increasing attention from researchers has been devoted to this process in recent years, with emphasis on mechanochemistry technology. The mechanochemical method can make technically feasible the recycling of metals from some specific wastes, such as cathode ray tube (CRT) funnel glass and tungsten carbide waste, while significantly improving recycling efficiency. Particle size reduction, specific surface area increase, crystalline structure decomposition and bond breakage have been identified as the main processes occurring during the mechanochemical operations in the studies. The activation energy required decreases and reaction activity increases, after these changes with activation progress. This study presents an overall review of the applications of mechanochemistry to metal recycling from wastes. The reaction mechanisms, equipment used, method procedures, and optimized operating parameters of each case, as well as methods enhancing the activation process are discussed in detail. The issues to be addressed and perspectives on the future development of mechanochemistry applied for metal recycling are also presented.

Occurrence, characteristics and leakage of polybrominated diphenyl ethers in leachate from municipal solid waste landfills in China

Raw leachate samples were collected from various municipal solid waste (MSW) landfills in a densely populated city in North China to measure the levels and compositional patterns of polybrominated diphenyl ethers (PBDEs) in leachate. The total concentration of PBDEs ranged from 4.0 to 351.2xa0ng/L, with an average of 73.0xa0ng/L. BDE-209 dominated the congeners in most of the samples, followed by BDE-47 and -99. Higher PBDEs concentrations were found in leachate from younger landfill facilities in the urban area. Pearson correlation analysis implied a potential dependence of the PBDEs level on landfill age, suspended solids and dissolved organic carbon, while the results of principal component analysis (PCA) suggested potential origins and transportation of PBDEs in leachate. The Monte Carlo method was adopted to estimate the annual leakage of PBDEs into the underground environment nationwide, based on two main scenarios: simple landfills with inadequate liner systems and composite-lined landfills with defective geomembranes.

Take back and treatment of discarded electronics: a scientific update

This paper indicates that the performance of tack-back and treatment of electronic waste (e-waste) system can be improved substantially. This can be reached by better taking into account in a better way the big variety in material composition and potential toxicity of electrical and electronic products - from a technical, organizational and regulatory perspective. Realizing that there is no ‘one size fit for all’ and combining smart tailor made solutions with economic of sale will result in the best environmental gain/cost ratio. Several examples show how science and engineering have supported or will support this approach.