Sorptive removal of disinfection by-product precursors from UK lowland surface waters: impact of molecular weight and bromide

The current study compared the impact of three different unit processes, coagulation, granular activated carbon (GAC), and a novel suspended ion exchange (SIX) technology, on disinfection by-product formation potential (DBPFP) from two UK lowland water sources with medium to high bromide content. Specific attention was given to the influence of the organic molecular weight (MW) fraction on DBPFP as well as the impact of bromide concentration. Whilst few studies have investigated the impact of MW fractions from Liquid Chromatography with Organic Carbon Detection (LC-OCD) analysis on dissolved organic carbon (DOC) removal by different processes, none have studied the influence of DOC MW fractions from this analysis on DBP formation. The impact of higher bromide concentration was to decrease the total trihalomethane (THM) and haloacetic acid (HAA) mass concentration, in contrast to previously reported studies. Results indicated that for a moderate bromide concentration source (135 μg/L), the THM formation potential was reduced by 22% or 64% after coagulation or SIX treatment, respectively. For a high bromide content source (210 μg/L), the THM formation potential removal was 47% or 69% following GAC and SIX treatment, respectively. The trend was the same for HAAs, albeit with greater differences between the two processes/feedwaters with reference to overall removal. A statistical analysis indicated that organic matter of MW > 350 g/mol had a significant impact on DBPFP. A multiple linear regression of the MW fractions against DBPFP showed a strong correlation (R2 between 0.90 and 0.93), indicating that LC-OCD analysis alone could be used to predict DBP formation with reasonable accuracy, and offering the potential for rapid risk assessment of water source

Delayed intracardial shunting and hypoxemia after massive pulmonary embolism in a patient with a biventricular assist device

We describe the interdisciplinary management of a 34-year-old woman with dilated cardiomyopathy three months postpartum on a cardiac biventricular assist device (BVAD) as bridge to heart transplantation with delayed onset of intracardial shunting and subsequent hypoxemia due to massive pulmonary embolism. After emergency surgical embolectomy pulmonary function was highly compromised (PaO2/FiO2 54) requiring bifemoral veno-venous extracorporeal membrane oxygenation. Transesophageal echocardiography detected atrial level hypoxemic right-to-left shunting through a patent foramen ovale (PFO). Percutaneous closure of the PFO was achieved with a PFO occluder device. After placing the PFO occluder device oxygenation increased significantly (Δ paO2 119 Torr). The patient received heart transplantation 20 weeks after BVAD implantation and was discharged from ICU 3 weeks after transplantation

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Mechanisms of Liquid-Metal-Activated Aluminum-Water Reactions and Their Application

The work presented in this thesis contributes to the fundamental understanding of the liquid-metal-activated aluminum-water reaction system, as well as methods that leverage these insights to improve the practicality of aluminum-based fuels. Water-reactive aluminum is a promising energy storage material given its ability to generate hydrogen and heat at a high volumetric energy density. Accounting for only the hydrogen released in this aluminum-water reaction, energy densities up to 36.3 MJ/L can be achieved, compared to 7.2 MJ/L for liquid hydrogen. The ability for this reaction to generate hydrogen on-demand also eliminates safety concerns associated with gaseous or liquid hydrogen storage. In addition, the heat generated from the aluminum oxidation (15.8 MJ/kg) can be used to power thermal processes including seawater desalination, making aluminum a potentially attractive fuel source for disaster relief applications in which debris can be mined for energy to generate critical resources like electricity and potable water. To make aluminum water-reactive, its natural oxide layer must first be disrupted. One promising activation approach is to introduce a liquid-phase gallium-indium eutectic (eGaIn) into the aluminum grain boundary network. While this method produces a highly reactive fuel with only roughly 5 wt.% added, viability for practical applications had hinged on several important but previously untested assumptions made in the literature. Specifically, the work presented in this thesis addresses the uncertainty around (1) whether the eGaIn can be recovered as a liquid post-reaction and recycled to activate more aluminum with minimal loss, (2) how the aluminum-water system performs at elevated pressures and with near-stoichiometric water inputs, and (3) whether this process can be applied to practical scrap aluminum with surface contamination and high alloying content. In this research, SEM-EDS and XRD analysis showed that the activating eGaIn cannot be recovered under standard reaction conditions (i.e. deionized water, 1 bar, 100 degC) due to dealloying of the gallium and indium at the microscale. It was then discovered that in ionic aqueous solutions, liquid-phase eGaIn emerges from solution under specific ambient conditions. From this discovery, a method for recovering and recycling the eGaIn was developed, using NaCl in moderate concentrations as the only additive. In following experiments, >99% of the input eGaIn was recovered and recycled to produce aluminum fuel with no observed loss in performance. With support from additional experimental evidence, it was hypothesized that the recoverability in this method is due to the development of a passivating electronic double layer at the eGaIn-electrolyte interface, thereby inhibiting gallium oxidation and subsequent dealloying. This proposed mechanochemical reaction theory was then extended to non-ionic solutions. A new experimental technique was developed in which aluminum and water can be reacted arbitrarily slowly in a non-aqueous environment via controlled exposure to room-temperature water vapor, enabling in-progress characterization via SEM-EDS and XRD techniques. This method was used to identify a two-part reaction mechanism in which the aluminum first disintegrates along its microstructure via a fractal-like exfoliation process, followed by its reaction with water at unoxidized sites along the freshly exposed grain surfaces. The indium in the activating alloy was shown to be crucial for the disintegration process specifically, and additional evidence suggests that the initial reaction driving the exfoliation is not a large-scale aluminum-water reaction, but possibly a gallium oxidation reaction instead. It was also shown that ambient oxygen in the reaction environment is capable of repassivating the exposed aluminum grains, severely limiting hydrogen yields. This reaction mechanism was then studied for constant volume, elevated ambient pressure, and near-stoichiometric water input conditions. An idealized thermodynamics model was developed and validation experiments showed that actual hydrogen yields are suppressed under each of these conditions. Reduced reactivity was observed for <10x stoichiometric water inputs, and experimental evidence suggests excess water is both being taken up into the crystalline reaction products via intercalation and also serves as a physical barrier preventing repassivation by ambient oxygen. It was discovered that by increasing the pH of the reaction environment, a two-fold increase in hydrogen production under near-stoichiometric conditions can be achieved. To account for the reduced reactivity in isochoric reactions, it was observed that the disintegration phase of the reaction mechanism is inhibited at high ambient pressures. Using these insights and empirical parameterizations of reactivity under these various conditions, the accuracy of the thermodynamics model was improved. Finally, a method for activating practical scrap aluminum using eGaIn was developed. Used aluminum beverage cans (UBCs) were selected as a challenging case study due to their thin geometry, polymer coatings, and high alloying content. It was demonstrated that shredding and compacting the UBCs into pellets under parameters optimized in this research for hydrogen production produces a fuel with consistent theoretical hydrogen yield fractions >0.97. The total energy input for this process was measured at 551 kJ/kg, only 1.8% of the embodied energy of the aluminum. A preliminary economics model that incorporates the results of this work predicts that the value of the electricity, potable water, and high-quality aluminum hydroxide produced by an aluminum oxidation power system is up to 9x that of the input scrap depending on location. In total, this work enables aluminum that would otherwise sit idle in a landfill to be mined locally for energy.Ph.D

Design of an aluminum-powered reverse osmosis desalination system for disaster relief

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 103-105).Fuel generated from highly energy-dense aluminum debris (23.3 kWh/L) is explored here as a means for producing electricity and clean water for disaster relief and preparedness. Energy is extracted from aluminum by first treating it with a minimal surface coating of gallium and indium (<3% by mass) and then reacting it with water to produce hydrogen, which can supply a fuel cell or internal combustion engine to generate electricity, and heat, which can be used to desalinate and purify seawater or contaminated fresh water. To use aluminum debris as fuel, it is necessary to first understand which of the many possible aluminum-water reactions occurs at given a temperature and pressure in order to accurately model such quantities as the heat released and the amount of water required stoichiometrically for the reaction to proceed.A new thermodynamics analysis is presented here that predicts these quantities by minimizing the Gibbs free energy over the possible reactions to determine which is most favorable under a wide range operating conditions. Reaction experiments at the extremities of this range validate these results. This new aluminum-water reaction model enables the design of a robust and minimally complex system that uses the heat released in this reaction to desalinate seawater. The system presented here uses a novel process called Heat-Driven Reverse Osmosis (HDRO), in which the release of thermal energy in an enclosed vessel pressurizes a working fluid up the high pressures required to drive reverse osmosis. Using the aluminum-water reaction as the heat source for this process, the theoretical upper limit performance ratio is shown to be 41 for 3.5% salinity seawater and maximum operating pressure of 138 bar, and an unoptimized prototype has achieved a performance ratio of 3.Additionally, because the hydrogen produced in the aluminum-water reaction is not consumed in this process, it can be used to generate electricity or desalinate additional water, further increasing the system wide efficiency. Thus, in addition to being well-suited for disaster relief, this technology is a potentially attractive option for large-scale desalination in drought prone regions as well.by Peter Godart.S.M.S.M. Massachusetts Institute of Technology, Department of Mechanical Engineerin

High-Power Fuel Cell Systems Fueled by Recycled Aluminum

Copyright © 2019 ASME. Presented here is a novel system that uses an aluminum-based fuel to continuously produce electrical power at the kW scale via a hydrogen fuel cell. This fuel has an energy density of 23.3 kWh/L and can be produced from abundant scrap aluminum via a minimal surface treatment of gallium and indium. These additional metals, which in total comprise 2.5% of the fuel’s mass, permeate the grain boundary network of the aluminum and disrupt its oxide layer, thereby enabling the fuel to react exothermically with water to produce hydrogen gas and aluminum oxyhydroxide, an inert and valuable byproduct. To generate electrical power using this fuel, the aluminum-water reaction is controlled via water input to a reaction vessel in order to produce a constant flow of hydrogen, which is then consumed in a fuel cell to produce electricity. As validation of this power system architecture, we present the design and implementation of two example systems that successfully demonstrate this approach. The first is a 3 kW emergency power supply and the second is a 10 kW power system integrated into a BWM i3 electric vehicle.Office of Naval Research (Grant N0001417MP00504

Kilowatt-Scale Fuel Cell Systems Powered by Recycled Aluminum

Abstract Presented here is a novel system that uses an aluminum-based fuel to continuously produce electrical power at the kilowatt scale via a hydrogen fuel cell. This fuel has an energy density of 23.3 kW h/L and can be produced from abundant scrap aluminum via a minimal surface treatment of gallium and indium. These additional metals, which in total comprise 2.5% of the fuel’s mass, permeate the grain boundary network of the aluminum to disrupt its oxide layer, thereby enabling the fuel to react exothermically with water to produce hydrogen gas and aluminum oxyhydroxide (AlOOH), an inert and valuable byproduct. To generate electrical power using this fuel, the aluminum–water reaction is controlled via water input to a reaction vessel in order to produce a constant flow of hydrogen, which is then consumed in a fuel cell to produce electricity. As validation of this power system architecture, we present the design and implementation of two proton-exchange membrane (PEM) fuel cell systems that successfully demonstrate this approach. The first is a 3 kW emergency power supply, and the second is a 10 kW power system integrated into a BMW i3 electric vehicle.US Office of Naval Research (Grant N0001417MP00504

Hydrogen production from aluminum-water reactions subject to varied pressures and temperatures

The production of hydrogen via an aluminum-water reaction is explored at temperatures and pressures ranging from 273.15 to 600 K and 0.1–10 MPa, respectively. Across this range, aluminum and water can react to form different aluminum oxide and hydroxide species, resulting in differences in the release of thermal energy, as well as the amount of water required stoichiometrically for the reaction to proceed. A model presented in this work uses the Gibbs free energy to predict the favorability of these byproducts as a function of temperature and pressure. At 0.1 MPa, this model predicts the primary favorability of Al(OH)₃ (gibbsite)below 294 K, AlOOH (boehmite)from 294 to 578 K, and Al₂O₃ (corundum)above 578 K. The results of this model were tested using a previously established technique for activating bulk aluminum via infusion of a gallium-indium eutectic into its grain boundary network. Reaction tests were performed at the extremities of the operating range of interest, and the composition of the byproducts from each test, determined via Fourier transform infrared spectroscopy (FTIR)and X-ray diffraction (XRD)analysis, were all in alignment with the model. Furthermore, reaction tests above 423 K at 0.1 MPa indicate limited reactivity of steam with aluminum activated in this manner. Consequently, the model is modified accordingly to show that Al₂O₃ cannot be achieved in practice with this method as its transition remains above the saturation temperature of water at the pressures studied here