Closed-loop recycling of polymers using solvents

Recycling of plastic is an established technology contributing to a circular economy. A sustainable society requires recycling to produce high quality feedstocks from all types of reusable waste. New recycling technologies will help to improve waste management practices, for instance dissolving plastic waste in a solvent to purify and maintain its material properties. In solution it is also possible to depolymerise polymers into monomers that can be used to remake virgin-grade material. In this review the advantages and disadvantages of three solvent-based recycling processes will be considered: separation of cotton and polyester (polyethylene terephthalate (PET)) textiles, chemical recycling of polylactic acid (PLA) and dissolution-precipitation of polyvinylchloride (PVC). The current state of the art and future prospects are discussed, including a brief overview of how solvents are being used to process other types of plastic waste

Thermal-hydraulic Optimization of the Heat Exchange Between a Molten Salt Small Modular Reactor and a Super-critical Carbon Dioxide Power Cycle

The next generation of nuclear power sources, Gen. IV, will include an emphasis on small, modular reactor (SMR) designs, which will allow for standardized, factory-based manufacturing and flexibility in the design of power plants by utilizing one or several modular reactor units in parallel. One of the reactor concepts being investigated is the Molten Salt Reactor concept (MSR), which utilizes a molten salt flow loop to cool the reactor and transfer heat to the power conversion cycle (PCS).Here, the use of a supercritical carbon dioxide (S-CO2) Brayton cycle is assumed for that PCS. The purpose of this thesis is to investigate the heat exchange between these two systems and to determine the suitability of a common heat exchanger concept, the shell-and-tube heat exchanger (STHE). This was accomplished using a code written in Python programming language that optimized the geometry ofa baffled STHE for a range of conditions the reflect MSR power plants currently in the design or concept stages. Star-CCM+ computational fluid dynamics (CFD)software was used to visualize the flow patterns of molten salt and CO2 in these STHE designs, and it was also used to determine heat transfer coefficients and pressure drops. These values were compared to those calculated by the optimizer code in order to validate its results. Finally, modularity analysis was performed for these STHE designs. Trends were generalized from these results that will contribute to judgments about the suitability of STHE’s for use with MSR’s and S-CO2

Suzuki-Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

The development and study of new solvents has become important due to a proliferation of regulations preventing or limiting the use of many conventional solvents. In this work, the suitability of the Suzuki-Miyaura reaction to demonstrate the usefulness of new solvents was evaluated, including Cyrene™, dimethyl isosorbide, ethyl lactate, 2-methyltetrahydrofuran (2-MeTHF), propylene carbonate, and γ-valerolactone (GVL). It was found that the cross coupling is often unaffected by the choice of solvent, and therefore the Suzuki-Miyaura reaction provides limited information regarding the usefulness of any particular solvent for organic synthesis

Effectiveness of Financial Incentives in Improving Breast Cancer Screening Among Medicaid Recipients

Breast cancer remains one of the leading causes of death among women. Roughly 2.4 million women are diagnosed annually with breast cancer throughout the world. Although breast cancer survival rates are favorable for the United States compared to other nations (90% 5-year survival for non-metastatic disease), it comes at a high cost. The United States spends an estimated $30 billion annually on breast cancer treatment. In addition, disparities in breast cancer survival rates also exist in the United States. Women Medicaid recipients, who are predominately minorities (60Significant efforts to improve breast cancer survival while reducing identified disparities and treatment costs have been underway for more than forty years. Advances in healthcare policy have played a critical role in saving lives and increasing access to breast cancer screening in the United States. Breast cancer screening is universally supported among professional societies as a tool to diagnose breast cancer in its earliest stages when it is most treatable. However, breast cancer screening is underutilized among Medicaid recipients, correlating with their higher rates of breast cancer mortality. The passage of the Affordable Care Act (2010) expanded access to health insurance for millions of Americans while allowing Medicaid organizations to compensate their recipients for participating in preventive health behaviors such as breast cancer screening. Financial incentives for preventive health behavior provided by Medicaid organizations have the potential to help cover out-of-pocket costs such as transportation, adult/childcare, or lost wages, as well as encourage Medicaid recipients to prioritize breast cancer screening and/or overcome apprehensions such as physical discomfort and fear of navigating the health care system. Using the Gelberg-Anderson Behavioral Model for Vulnerable Populations, a retrospective quantitative study was conducted to assess the role of financial incentives in the utilization of breast cancer screening among Medicaid recipients (aged 50-64) residing in Baltimore, Maryland. The study aimed to answer the following research questions: One, do financial incentives increase the utilization of breast cancer screening among women with Medicaid aged between 50 and 74 compared to women who do not receive financial incentives? Two, are higher amounts of financial incentives associated with greater utilization of breast cancer screening? Three, what population characteristics are associated with higher utilization of breast cancer screenings among Medicaid recipients when financial incentives are provided? The study included 2,578 unique Medicaid recipients who were not current with their breast cancer screening when applying the US Preventive Services Task Force recommendations (2016). Between 2019 and 2022, 738 breast screening exams were completed. Two cohorts were established in the study. One cohort did not receive a financial incentive (392) for breast cancer screening, and a second cohort did receive a financial incentive (2,186) for breast cancer screening. Logistic regression was the primary statistical tool for answering all three research questions. The dependent variable for all three questions was dichotomous, specifically, was a breast cancer screening claim identified (yes/no)? The predictor variable was the use of financial incentives which had three levels,$75, $100, and$150. Covariates such as age (years), race, geographic sub-region of Baltimore, Maryland for the primary residence, and the number of people reported as living with the Medicaid recipient (household count) were considered when assessing the role of population characteristics and breast cancer screening utilization when a financial incentive was provided. The primary question considered by the study was asking if financial incentives provided to Medicaid recipients increased the utilization of breast cancer screening. The study findings were inconclusive. A secondary question considered if larger-sized financial incentives increased the likelihood of breast cancer screening compared to when a smaller incentive was provided. It was identified that the smaller financial incentive ($75) was statistically significant (p-value \u3c 0.001) for increasing the likelihood of breast cancer screening utilization while the larger financial incentives ($100 or $150) were not found to be statistically significant. The covariates of the Baltimore sub-region and the household count were identified to be not statistically significant in either the financial incentive or no financial incentive cohorts. Alternatively, the age (OR=1.07, 95% CI 1.04, 1.11, p-value \u3c0.05) and race covariates were identified as being statistically significant (p-value \u3c0.05) when a financial incentive was provided to increase breast cancer screening among Medicaid recipients. It was noted that American Indian/Alaskan Native and Black participants who received a financial incentive had a statistically significant (p-value \u3c0.05) increase in their likelihood of utilizing breast cancer screening

Relation of Sediment and Nutrient Loads to Watershed Characteristics and Land Use in the Otisco Lake Basin, Onondaga County, New York

Otisco Lake, the smallest and easternmost of New York State \u27s Finger Lakes, is the source of water supply for several villages in Onondaga County. In recent years, turbidity and algal blooms have periodically impaired the lake \u27s use for both water supply and recreation. Principal land uses within the Otisco Lake basin are woodland (39%) and cropland (49%). Conservation practices such as contour farming, strip cropping, and diversion ditches are applied to about 47% of the cropland in the basin. Runoff and concentrations of sediment and nutrients in the five major tributaries, which together drain about 70% of the lake \u27s watershed, were monitored from November 1981 through September 1983, and sediment and nutrient loads from the ungaged areas of the watershed were estimated. Otisco Lake received 10,600 tons of sediment, 20,600 lbs of phosphorus asp, 199,000 lbs of total kjeldahl nitrogen as N, and 236,000 lbs of nitrite plus nitrate as N from the five tributaries and the ungaged area during the 23-month study. Spafford Creek basin (12.0 sq mi) contributed about 72% of the annual sediment load and 46% of the annual nutrient load; the other four subbasins, which range from 2.6 to 3.7 sq mi in area, each contributed 3 to 5% of the annual sediment load and 6 to 16% of the annual nutrient load. The ungaged part of the watershed contributed 12% of the annual sediment load and 28% of the annual nutrient load. Concentrations of ammonia as N were relatively uniform through the year, although some extremely high concentrations occurred during the summer. Total Kjeldahl nitrogen concentrations were highest in the summer and lowest in the fall. Concentrations of nitrite plus nitrate were significantly lower in winter than in the rest of the year. Total phosphorus concentrations were slightly higher in the spring than at other times, and concentrations of dissolved phosphorus were slightly higher in the summer. Storms and snowmelt accounted for 70 to 90% of the runoff, 90 to 99% of the sediment load, and 70 to 98% of the nutrient loads from the tributaries. The largest nutrient loads occurred during the spring of each year, when runoff was highest. About 70% of the sediment, 60% of total Kjeldahl nitrogen, 58% of total phosphorus, and 53% of nitrite plus nitrate were transported during spring high flows. (Lantz-PTT

Circular economy design considerations for research and process development in the chemical sciences

A circular economy will look to chemistry to provide the basis of innovative products, made from renewable feedstocks and designed to be reused, recycled, or the feedstock renewed through natural processes. The substances that products are made of will increasingly be treated as a resource equal to the raw materials, and not just disposed of. This perspective discusses the role of chemists in a world without waste

Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources

The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents

Editorial for the "Green Chemistry" Section in the Journal Molecules : Focus on Solvents

It is a pleasure to write this editorial highlighting some of the recent papers discussing solvents in the Green Chemistry section of Molecules [...]