Planet-compatible pathways for transitioning the chemical industry.

Chemical products, such as plastics, solvents, and fertilizers, are essential for supporting modern lifestyles. Yet, producing, using, and disposing of chemicals creates adverse environmental impacts which threaten the industry's license to operate. This study presents seven planet-compatible pathways toward 2050 employing demand-side and supply-side interventions with cumulative total investment costs of US$1.2-3.7 trillion. Resource efficiency and circularity interventions reduce global chemicals demand by 23 to 33% and are critical for mitigating risks associated with using fossil feedstocks and carbon capture and sequestration, and constraints on available biogenic and recyclate feedstocks. Replacing fossil feedstocks with biogenic/air-capture sources, shifting carbon destinations from the atmosphere to ground, and electrifying/decarbonizing energy supply for production technologies could enable net negative emissions of 0.5 GtCO2eq y-1 across non-ammonia chemicals, while still delivering essential chemical-based services to society.

Evaluation of automatic cleaning in analysis of occlusal force.

This study aimed to clarify the usefulness of automatic cleaning in analysis of occlusal force. The maximum occlusal force was calculated in 151 healthy adults before cleaning (B), after manual cleaning (M), and after automatic cleaning (A) and compared among the three conditions. The absolute value of the error rate of A, based on M, was calculated. The occlusal forces in M and A were similar and significantly smaller than the occlusal force in B. The absolute error rate of A was 2.4%. These results suggest that automatic cleaning has a similar effect to manual cleaning and can be applied clinically.

Separation of cathode particles and aluminum current foil in lithium-ion battery by high-voltage pulsed discharge Part II: Prospective life cycle assessment based on experimental data.

This series of papers addresses the recycling of cathode particles and aluminum (Al) foil from positive electrode sheet (PE sheet) dismantled from spent lithium-ion batteries (LIBs) by applying a high-voltage pulsed discharge. As concluded in Part I of the series (Tokoro et al., 2021), cathode particles and Al foil were separated in water based on a single pulsed power application. This separation of LIB components by pulsed discharge was examined by means of prospective life cycle assessment and is expected to have applications in LIB reuse and recycling. The indicators selected were life cycle greenhouse gas (LC-GHG) emissions and life cycle resource consumption potential (LC-RCP). We first completed supplementary experiments to collect redundant data under several scale-up circumstances, and then attempted to quantify the uncertainties from scaling up and progress made in battery technology. When the batch scale of pulsed discharge separation is sufficiently large, the recovery of cathode particles and Al foil from PE sheet by pulsed discharge can reduce both LC-GHG and LC-RCP, in contrast to conventional recycling with roasting processes. Due to technology developments in LIB cathodes, the reuse of positive electrode active materials (PEAM) does not always have lower environmental impacts than the recycling of the raw materials of PEAM in the manufacturing of new LIB cathodes. This study achieved a proof of concept for resource consumption reduction induced by cathode utilization, considering LC-GHG and LC-RCP, by applying high-voltage pulsed discharge separation.

Separation of cathode particles and aluminum current foil in Lithium-Ion battery by high-voltage pulsed discharge Part I: Experimental investigation.

To enable effective reuse and recycling processes of spent lithium-ion batteries (LiBs), here we develop a novel electrical method based on a high-voltage pulsed discharge to separate cathode particles and aluminum (Al) foil. A cathode particle sample was mechanically separated from a LiB, cut into 30-mm × 80-mm test pieces, and subjected to a high-voltage electrical pulse discharge from either end in water. At a voltage of 25 kV, 93.9% of the cathode particles separated from the Al foil. These particles were easily recovered by sieving at 2.36 mm because the Al foil retained its shape. Some Al contaminated the particles owing to generation of hot plasma and subsequent shock waves; however, the Al concentration in the recovered cathode particles was limited to 2.95%, which is low enough to allow for further cobalt and nickel recovery by hydrometallurgical processing. The results of heat balance calculations obtained from the current waveforms suggested that polyvinylidene fluoride, the main component of the adhesive in the cathode particle layers, melted and lost its adhesion through Joule heating of the Al foil at the maximum current of 19.0 kA at 25 kV. Almost 99% of the recovered cathode particles maintained their chemical composition and form after separation, and therefore could potentially be directly reused in LiBs.

Monitoring and analysis of solvent emissions from metal cleaning processes for practical process improvement.

OBJECTIVES: Industrial cleaning processes are a major source of emissions of chlorinated organic solvents in Japan. Solvent emission mechanisms from metal cleaning processes were analysed to support process improvement aimed at emission reductions. METHODS: The amounts of solvents directly emitted from a washing machine and solvents taken out by metal parts to be cleaned were measured in laboratory experiments using an industrial washing machine. Direct emissions to a local ventilation system and to the workplace were analysed, while several process conditions were changed. The drying rate of solvents on surfaces was analysed for seven metal parts to clarify the effects of their materials and shape. RESULTS: The results for direct solvent emissions show that solvents emitted because of the movement of metal parts inside a washing machine can be mainly exhausted through a local ventilation system, while the operation of an ultrasonic device can increase solvent diffusion to the workplace. Lowering the cooling water temperature can be effective in avoiding such solvent diffusion to the workplace. The results also show that the heat capacity and shape complexity of metal parts can affect the drying rate of solvents on their surfaces. CONCLUSIONS: Analysis of the results shows the effectiveness of using a local ventilation system and cooling pipes in controlling solvent emissions for several work tasks. The minimum time required to dry all solvents on the surface of metal parts was also estimated. Analyses of the emission mechanisms in this study clarified the major factors in solvent emissions and the effectiveness of process modifications for emission reductions. The findings are applicable to practical process improvement aimed at emission reductions in cleaning sites.

Analysis of supercritical water oxidation for detoxification of waste organic solvent in university based on life cycle assessment.

Spray incineration and supercritical water oxidation (SCWO) processes have been used for detoxifying waste organic fluids in the University of Tokyo. In this study, we aim to elucidate the environmental aspects of these waste treatment processes by life cycle assessment (LCA). Through the investigation of actual plants, the inventory data and other characteristics of actual plants were collected and analyzed. To confirm the potential of SCWO, three modification types of the process and operation were considered and assessed on the basis of estimated inventory data. The results demonstrate that spray incineration has less environmental impact than SCWO in all scenarios. However, SCWO has various advantages for installation as a treatment process in universities such as negligible risk of creating dioxins and particulate matter. Proper choice of the treatment method for organic waste fluid requires a comprehensive analysis of risks. Spray incineration poses the risk of providing dioxins and particulate matter, while SCWO has such risk at negligible level. This means that waste including concerned materials related to such emission should be treated by SCWO. Using the right technologies for the right tasks in the detoxification of hazardous materials should be implemented for sustainable universities.

Practical method of assessing local and global impacts for risk-based decision making: a case study of metal degreasing processes.

For risk-based decision making, local and global impacts should be considered simultaneously. In metal degreasing processes, various cleansing agents are used and a significant amount of such cleansing agents is released into the environment. An appropriate measure of reducing chemical risk associated with industrial cleaning processes should be implemented on the basis of evaluation results representing the local and global impacts. In this study, we assessed metal degreasing processes using a chlorinated solvent with an open-top washing machine and four alternative scenarios, namely, improving the settings of the machine (two cases), changing the local ventilation system, and installing a recovery system using activated carbon. The applied methods are plant-specific risk and life cycle assessments. Specifically in the risk assessment, detailed process data available for decision makers are utilized to evaluate occupational and neighborhood risks. The results of this case study indicate a tradeoff relationship between the local and global impacts in metal degreasing. Through the discussions on the practicability of the integration of the local and global impacts into actual decision making, we conclude that the way to use, select, or integrate risk and life cycle assessments should be analyzed systematically as the situation demands at decision making.