Environmental and risk screening for prioritizing pollution prevention opportunities in the U.S. printed wiring board manufacturing industry

Five-Axis Curved-Surface Multi-Material Printing on Conformal Surface to Construct Aqueous Zinc-Ion Battery Modules

Compact batteries and electronic devices offer a plethora of advantages, including space optimization, portability, integration capability, responsiveness, and reliability. These attributes are crucial technical enablers for the design and implementation of various electronic devices and systems within scientific exploration. Thus, the group harnesses additive manufacturing technology, specifically utilizing five-axis curved-surface multi-material printing equipment, to fabricate aqueous zinc-ion batteries with tungsten-doped manganese dioxide cathode for enhanced adaptability and customization. The five-axis linkage motion system facilitates shorter ion transportation paths for compact batteries and ensures precise and efficient molding of non-developable curved surfaces. Afterward, the compact cell is integrated with a printed nano-silver serpentine resistor temperature sensor, and an integrated functional circuit is created using intense-pulse sintering. Incorporating an emitting Light Emitting Diode (LED) allows temperature measurement through variations in LED brightness. The energy storage module with a high degree of conformity on the carrier surface has the advantages of small size and improved space utilization. The capability to produce Zinc-ion batteries (ZIBs) on curved surfaces presents new avenues for innovation in energy storage technologies, paving the way for the realization of flexible and conformal power sources.

Programmed multimaterial assembly by synergized 3D printing and freeform laser induction

In nature, structural and functional materials often form programmed three-dimensional (3D) assembly to perform daily functions, inspiring researchers to engineer multifunctional 3D structures. Despite much progress, a general method to fabricate and assemble a broad range of materials into functional 3D objects remains limited. Herein, to bridge the gap, we demonstrate a freeform multimaterial assembly process (FMAP) by integrating 3D printing (fused filament fabrication (FFF), direct ink writing (DIW)) with freeform laser induction (FLI). 3D printing performs the 3D structural material assembly, while FLI fabricates the functional materials in predesigned 3D space by synergistic, programmed control. This paper showcases the versatility of FMAP in spatially fabricating various types of functional materials (metals, semiconductors) within 3D structures for applications in crossbar circuits for LED display, a strain sensor for multifunctional springs and haptic manipulators, a UV sensor, a 3D electromagnet as a magnetic encoder, capacitive sensors for human machine interface, and an integrated microfluidic reactor with a built-in Joule heater for nanomaterial synthesis. This success underscores the potential of FMAP to redefine 3D printing and FLI for programmed multimaterial assembly.

60Co-γ Irradiation-Induced Shift and Polarity Reversal in the Triboelectric Series of Poly(ether sulfone)s

The sensitivity of triboelectric nanogenerators (TENGs) to the surface charge density highlights the significance of triboelectric materials and their modifications. Efforts have been directed toward developing effective strategies for increasing the surface charge density, expanding the potential applications of TENGs. This study proposes the use of irradiation technology for grafting to modify the electron-donating capability of poly(ether sulfone) (PES), thereby affording a dual benefit of enhancing the surface charge density and inducing a shift in the position of PES from negative to positive within the triboelectric series. The TENG based on grafted PES has resulted in a significant 3-fold increase in surface charge density compared to that of pristine PES, reaching 263 μC m-2. The surface charge density can be further increased to 502 μC m-2 through charge pumping. Notably, irradiation technology presents advantages over chemical grafting methods, particularly in terms of sustainability and environmental friendliness. This innovative approach shows great potential in advancing the domain of TENGs.

A methodology to screen priority toxins in pollutant release inventories

Pollutant release inventories are used for environmental policy making to reduce toxic pollutants, even though the quantity-based inventory analysis does not take into account the relative toxicity of pollutants. To overcome this limit, life cycle impact assessment (LCIA)-based inventory analysis was developed but still has a high uncertainty from modelling the site- and time-specific fates and transports of pollutants. Thus, this study develops a methodology to evaluate toxicity potentials based on the concentration of pollutants in the exposure to humans in order to circumvent the uncertainty and subsequently screen priority toxins in pollutant release inventories. This methodology combines (i) analytical measurement of the concentration of the pollutants exposed to humans; (ii) application of toxicity effect characterization factors for pollutants; and (iii) identification of priority toxins and industries based on the toxicity potential evaluation results. To demonstrate the methodology, a case study is considered, evaluating toxicity potentials from the ingestion of heavy metals in seafood organisms and then identifying priority toxins and industry sectors in a pollutant release inventory. The results of the case study show that the methodology-based priority pollutant is different from the quantity- and LCIA-based ones. Therefore, the methodology can contribute to making effective environmental policy.

Halide-induced dissolution of lead(IV) oxide in frozen solution

The dark dissolution behavior of plattnerite (ß-PbO₂) was investigated in frozen solutions containing halide ions and compared with those in aqueous solution. The amount of dissolved lead in the frozen solutions varied depending on the solution pH and the kind and concentration of halide ions. The presence of bromide and iodide ions enhanced the dissolution of lead in the aqueous phase, whereas the effect of chloride was insignificant. Compared with the aqueous phase dissolution, ß-PbO₂ dissolution in the frozen solution was slightly enhanced in the presence of bromide but suppressed in the presence of iodide. Iodide ions seemed to be relatively more trapped in the bulk ice (ice-crystal lattice) than bromide ions, which might be related to the suppressed dissolution of lead oxide in the presence of iodide. The co-existence of bromide (or iodide) and chloride ions in the frozen solution enhanced the dissolution of lead, which seems to be enabled by an additional reaction pathway involving the formation of mixed halide radicals, whereas such kind of synergistic enhancements were not observed in aqueous solution. The halide-induced lead oxide dissolution in frozen solutions can be related to the behavior of lead ions found in various media of frozen environments.

Insight into the tolerance, biochemical and antioxidative response in three moss species on exposure to BDE-47 and BDE-209

Responses of Hypnum plumaeforme, Thuidium cymbifolium, and Plagiomnium cuspidatum to short-term (96 h) BDE-47 and BDE-209(0, 0.005, 0.05, 0.5, and 5 μM, respectively) stress were investigated. Both BDE-47 and BDE-209 increased the lipid peroxidation in the three moss species, malondialdehyde (MDA) content increased with the elevated concentration of contaminants, and followed the order: P. cuspidatum > H. plumaeforme > T. cymbifolium on exposure to different concentrations. BDE-47 and BDE-209 stimulated the superoxide dismutase (SOD) and peroxidase (POD) activity of the three moss species, indicating that they played an important role in preventing oxidative stress. Reactive oxygen species (ROS) accumulation was positively correlated with the level of contaminants. The response of anti-oxidative enzymes to BDE-47 and BDE-209 stress differed among the three species. At 5  μM BDE-47 and BDE-209 treatment, the chlorophyll content of T. cymbifolium was even a little higher than the control group. Proline played an important role for the scavenging of ROS in P. cuspidatum and T. cymbifolium. In summary, BDE-47 was more toxic to the three moss species than BDE-209. P. cuspidatum was the most sensitive and T. cymbifolium was the most tolerant species to BDE-47 and BDE-209 stress. The strong resistance and tolerance of T. cymbifolium, combined with sensitive/moderate anti-oxidative response could elucidate its potential use as bio-indicator in the ecological risk assessment of BDE-47 and BDE-209 contamination.

Twice the effort: Ineffectiveness of selecting air pollution control targets with emission quantity for risk reduction

Protection of human health from air pollution has been typically pursued primarily via regulations of air quality standards and emission standards. Although reducing air pollution from the largest sources and placing more stringent emission limits on the industries of focus is a criterion used by decision makers to control air pollution, it is not clear whether this criterion is the most effective and efficient in improving health protection. Pollutants released from sources into the environment are spatially fluctuating rather than uniformly distributed, and hence, health risk is an issue of geographic variability. To address this issue, this study used a representative example of lead (Pb) in Taiwan. This study implemented an IO-RA methodology to redefine the effectiveness of air pollution management and rank the control priorities of target industries using different perspectives, i.e., environmental responsibility, economic benefit and repercussion potential. This study also considered the potential differences in policy effectiveness based on the air pollution control targets and ranked the industries according to their effectiveness in health risk improvement across the three perspectives and pure emission quantities. After determining the cause-effect chain of health risk through IO-RA, authorities can partner with specific industries according to the chosen effectiveness criteria and thus facilitate better policy performance.

Closed-Loop Electrochemical Recycling of Spent Copper(II) from Etchant Wastewater Using a Carbon Nanotube Modified Graphite Felt Anode

Developing effective technologies for treatment of spent etchant in printed circuit boards industries is of paramount for sustainable copper reuse and reducing copper discharge. We developed a novel closed-loop electrochemical cell for on-site regeneration of spent acidic cupric chloride etchant. It does not have any emissions and recycles all the copper using a three-dimensional graphite felt anode decorated with carbon nanotube (CNT/GF). The CNT/GF anode oxidizes Cu(I) to Cu(II) so that the spent cuprous chloride can be converted to cupric chloride and reused. The decorated CNT layer with abundant oxygen-containing functional groups significantly enhanced the electrocatalytic activity for Cu(II)/Cu(I) redox. The CuCl₃^2- is oxidized to CuCl⁺ at the anode and the CuCl⁺ is reduced to Cu(0) at the cathode. The closed-loop cycle system converts the catholyte into the anolyte. On average, the energy consumption of Cu(I) oxidation by CNT/GF is decreased by 12%, comparing to that by untreated graphite felt. The oxidation rate of Cu(I) is determined by the current density, and there is no delay for the mass transport of Cu(I). This study highlights the outstanding electrocatalytic performance, the rapid mass-transfer kinetics, and the excellent stability of the CNT/GF electrode, and provides an energy-efficient and zero-emission strategy for the regeneration of etchant waste.

Environmental risk assessment of wastewaters from printed circuit board production: A multibiomarker approach using human cells

Since the production of printed circuit boards (PCBs) generates wastewater contaminated with heavy metals and organic matter, PCB factories represent potential pollution sites. The wastewater toxicologically tested in this study contained several metals and the most abundant were copper and iron. At two exposure times tested (4 and 24 h) PCB wastewater (PCBW) proved to be cytotoxic (decreased cell viability) and genotoxic (increased comet assay tail intensity and tail moment) to human blood peripheral lymphocytes in vitro, and the oxidative stress parameter (malondialdehyde concentration) was also found to be higher. After application of combined treatment by waste base, ozone and waste sludge methods, concentrations of metals in purified PCBW were below the upper permitted levels and all tested toxicological parameters did not differ compared to the negative control. Taken together, similar methods could be implemented in PCB factories before discharging potentially toxic wastewater into the environment because purified PCBW does not represent a threat from the aspect of cytotoxicity and genotoxicity.

Using risk elasticity to prioritize risk reduction strategies for geographical areas and industry sectors

The total quantity of chemical emissions does not take into account their chemical toxicity, and fails to be an accurate indicator of the potential impact on human health. The sources of released contaminants, and therefore, the potential risk, also differ based on geography. Because of the complexity of the risk, there is no integrated method to evaluate the effectiveness of risk reduction. Therefore, this study developed a method to incorporate the spatial variability of emissions into human health risk assessment to evaluate how to effectively reduce risk using risk elasticity analysis. Risk elasticity analysis, the percentage change in risk in response to the percentage change in emissions, was adopted in this study to evaluate the effectiveness and efficiency of risk reduction. The results show that the main industry sectors are different in each area, and that high emission in an area does not correspond to high risk. Decreasing the high emissions of certain sectors in an area does not result in efficient risk reduction in this area. This method can provide more holistic information for risk management, prevent the development of increased risk, and prioritize the risk reduction strategies.

PM2.5, PM10 and health risk assessment of heavy metals in a typical printed circuit noards manufacturing workshop

A typical Printed Circuit Board (PCB) manufacturer was chosen as the object of this study. During PCB processing, fine particulate matter and heavy metals (Cu, Zn, Pb, Cr, Cd and Ni) will be released into the air and dust, which then impact workers' health and the environment. The concentrations of total suspended particle (TSP), PM10 and PM2.5 in the off-site were 106.3, 90.0 and 50.2μg/m(3), respectively, while the concentrations of TSP, PM10 and PM2.5 in the workshops ranged from 36.1 to 365.3, from 27.1 to 289.8 and from 22.1 to 212.3μg/m(3), respectively. Almost all six of the heavy metals were detected in all of the particle samples except Cd. For each workshop, it was obvious that Zn was the most enriched metal in TSP, followed by Cu>Pb (Cr)>Ni>Cd, and the same trend was found for PM10 and PM2.5. In the dust samples, Cu (which ranged from 4.02 to 56.31mg/g) was the most enriched metal, followed by Zn, Cr, Pb, Ni and Cd, and the corresponding concentrations ranged from 0.77 to 4.47, 0.37 to 1.59, 0.26 to 0.84, 0.13 to 0.44 and nd to 0.078mg/g, respectively. The health risk assessment showed that noncancerous effects are unlikely for Zn, Pb, Cr, Cu, Cd and Ni. The carcinogenic risks for Cd and Ni were all lower than 10(-6), except for Cr. This result indicates that carcinogenic risks for workers are relatively possible in the workshops. These findings suggest that this technology is advanced from the perspective of environmental protection in the waste PCB's recycling industry.

Occurrences and inventories of heavy metals and brominated flame retardants in wastes from printed circuit board production

Pollutants including heavy metals and brominated flame retardant were detected in 10 types of production wastes from a typical printed circuit board manufacturing plant, and their inventories were estimated. Rinsing water from etching process had the highest concentrations of copper (665.51 mg/L), lead (1.02 mg/L), nickel (3.60 mg/L), chromium (0.97 mg/L), and tin (1.79 mg/L). Powdered solid waste (SW) from the cut lamination process contained the highest tetrabromobisphenol-A (TBBPA) levels (49.86 mg/kg). Polybrominated diphenyl ethers (PBDEs) were absent in this plant, in agreement with the international regulations of PBDE phase out. The pollutant inventories in the wastes exhibited in the order of copper > > zinc > tin ≈ nickel > lead > chromium > > TBBPA. The potential environmental impact of pollutants in SW during production and disposal were further investigated. A high partitioning of pollutant concentration between the total suspended particle and SW (-0.10 < log K TS < 2.12) was observed for most pollutants, indicating the emission pathway from SW to the airborne atmosphere in the workshop. Although SW met the toxicity characteristic leaching procedure, drilling powder with the smallest particle diameter still showed high leachabilities of lead and tin which may lead to a negative environmental impact during disposal.

Tetrabromobisphenol A contamination and emission in printed circuit board production and implications for human exposure

The emission of and exposure to tetrabromobisphenol A (TBBPA) during the production of printed circuit boards (PCBs) were evaluated in this study. TBBPA was determined in production wastes (fine solid waste, rinsing water, effluent and sludge) and environmental samples (dust and PM10) from a typical PCB plant. The TBBPA concentrations of the solid and liquid wastes were on the order of 10(2)-10(4)ng/g and 10(1)-10(2)ng/L, respectively. The highest emission to the environment was exhibited by the fine solid waste (187-1220μg/kg-PCB), suggesting the need for strict control of its production and disposal. Regarding the environmental samples, the TBBPA contents of dust (125-9090ng/g) and PM10 (12.3-1640pg/m(3)) were higher than other values reported worldwide, indicating that PCB production was a non-negligible source of TBBPA for the occupational environment. TBBPA contamination mainly occurred in the form of sedimentary dust rather than suspended particulate matter. According to our estimation, worker exposures to TBBPA via dust ingestion, dust dermal absorption and PM10 inhalation varied widely by process, with the greatest exposures being 1930, 431 and 96.5pg/kg-bw/day, respectively. The exposure via dust represented most of the overall exposure via the above three pathways in PCB workshops.

Potential environmental impacts from the metals in incandescent, compact fluorescent lamp (CFL), and light-emitting diode (LED) bulbs

Artificial lighting systems are transitioning from incandescent to compact fluorescent lamp (CFL) and light-emitting diode (LED) bulbs in response to the U.S. Energy Independence and Security Act and the EU Ecodesign Directive, which leads to energy savings and reduced greenhouse gas emissions. Although CFLs and LEDs are more energy-efficient than incandescent bulbs, they require more metal-containing components. There is uncertainty about the potential environmental impacts of these components and whether special provisions must be made for their disposal at the end of useful life. Therefore, the objective of this study is to analyze the resource depletion and toxicity potentials from the metals in incandescent, CFL, and LED bulbs to complement the development of sustainable energy policy. We assessed the potentials by examining whether the lighting products are to be categorized as hazardous waste under existing U.S. federal and California state regulations and by applying life cycle impact-based and hazard-based assessment methods (note that "life cycle impact-based method" does not mean a general life cycle assessment (LCA) but rather the elements in LCA used to quantify toxicity potentials). We discovered that both CFL and LED bulbs are categorized as hazardous, due to excessive levels of lead (Pb) leachability (132 and 44 mg/L, respectively; regulatory limit: 5) and the high contents of copper (111,000 and 31,600 mg/kg, respectively; limit: 2500), lead (3860 mg/kg for the CFL bulb; limit: 1000), and zinc (34,500 mg/kg for the CFL bulb; limit: 5000), while the incandescent bulb is not hazardous (note that the results for CFL bulbs excluded mercury vapor not captured during sample preparation). The CFLs and LEDs have higher resource depletion and toxicity potentials than the incandescent bulb due primarily to their high aluminum, copper, gold, lead, silver, and zinc. Comparing the bulbs on an equivalent quantity basis with respect to the expected lifetimes of the bulbs, the CFLs and LEDs have 3-26 and 2-3 times higher potential impacts than the incandescent bulb, respectively. We conclude that in addition to enhancing energy efficiency, conservation and sustainability policies should focus on the development of technologies that reduce the content of hazardous and rare metals in lighting products without compromising their performance and useful lifespan.