Sorbent stability poses significant impacts on long-term performance of direct air capture (DAC) of CO2 and levelized cost of capture (LCOC). We report the DAC performance degradation of amine-infused fiber sorbents based on poly-(ethylenimine) (PEI), mesoporous SiO2, and cellulose acetate (CA) over CO2 cyclic sorption cycles in a nonoxidative environment. Infrared and nuclear magnetic resonance spectra indicate that the aminolysis reactions between CA ester moieties and PEI amine sites lead to the formation of acetamides and hence lower CO2 affinities of the sorbents. This stability issue can be remedied by hydrolysis treatment of the CA fiber sorbents before PEI impregnation or replacing CA with poly-(ether sulfone). This study underscores the importance of selecting proper support or additive materials of DAC contactors that are compatible with active species of CO2 capture.

Direct air capture (DAC), which captures CO2 from ambient air, is a critical technology to reduce greenhouse gases in the atmosphere in order to avoid climate disasters. Due to the relatively low concentration of CO2 (400 ppm), a large amount of air needs to be moved through DAC devices, which requires lots of energy. Currently, DAC technologies are deployed mainly in centralized systems and require extensive infrastructure and initial capital cost. A potential solution is to utilize existing infrastructure for DAC. In this study, we propose a distributed DAC system that utilizes existing commercial rooftop heating and air conditioning (HVAC) units to capture CO2 from the air. There are approximately 15 million such units already installed on commercial buildings in the United States, and they move a large amount of air every day. Adding DAC functionality to these units will significantly reduce the cost of infrastructure and operation. A modular approach was used to introduce DAC into a rooftop unit. Modules filled with triethylenetetramine-functionalized polyacrylonitrile sheets were developed and installed on the condenser coil side of the rooftop unit. The rooftop unit with DAC functions effectively captured CO2 from the air, and the addition of the DAC modules had little effect on the unit's original functionality. A preliminary techno-economic analysis was also conducted, and the results potentially suggest that utilizing existing commercial rooftop units for carbon capture is a feasible approach to reducing greenhouse gases. Direct air capture (DAC), which captures CO2 from ambient air, is a critical technology to reduce greenhouse gases in the atmosphere in order to avoid climate disasters.

Building-integrated carbon capture technology has the potential to reduce the cost of CO2 capture while improving indoor air quality (IAQ). To promote the adoption of CO2 capture in a building environment, this study investigated the possibility of integrating carbon capture technology with an existing rooftop make-up air unit (MAU) system to trap CO2. Here, a modular compact CO2 capture system containing amine-functionalized polymer fibers was examined. The system, which was installed at the exhaust of the MAU, captures CO2 before it leaves the building to enter the atmosphere as a greenhouse gas. The demonstrated average amount of CO2 captured was 1.1-1.4 mmol/g of adsorbent material. Techno-economic analysis (TEA) was further performed on the CO2 capture system, considering material costs, energy costs, as well as transportation and regeneration costs. These results were then used to estimate the levelized cost per ton CO2 captured (LCOC). To achieve LCOC below $100/t-CO2, adsorbents should have working capacities of 4.9 t and 3 t-CO2/year for 5 years and 10 years of operation, respectively. In summary, this study highlights a viable path toward the decarbonization of the commercial buildings sector and provides quantitative performance and economic insight on the suitability of building-integrated carbon capture technology.

The compatibility of a fast-pyrolysis bio-oil with 17 elastomer and 21 plastic materials common to fuel storage, dispensing, and delivery systems was assessed by measuring volume and hardness. Diesel was used as the baseline for comparison. The elastomer and plastic specimens were exposed to the test fuels at 23 degrees C. The exposure times were 4 and 16 weeks for the elastomers and plastics, respectively. The elastomers (except for silicone and styrene butadiene) exhibited pronounced swelling in the bio-oil. This was especially true for the fluorocarbons and acrylonitrile rubbers. For the elastomers, a strong correlation between polarity and volume swell was observed. Compositional and structural analysis on one of the fluorocarbon materials showed that the bio-oil was less effective at extracting phthalate additives than the diesel. However, the crystallinity of a fluorocarbon was altered by the bio-oil. Unlike the elastomers, the plastic materials were less impacted by exposure to the bio-oil. This finding is attributed to their denser and more rigid molecular structures (compared to the elastomers). Notable swelling did occur in the nylons, but this swelling was attributed to water absorption rather than polarity. Comparison with previous studies showed that the observed swelling was lower for both the elastomers and the plastics. Solubility (and hence swell) increases with temperature, and because this study was conducted at 23 degrees C rather than 50 degrees C, the reduced temperature is responsible for the lower swell levels.

The compatibility of 17 elastomers with two dioxolane molecules was assessed by volume change and hardness measurements. Each molecule was blended with diesel in concentrations of 0, 10, 20 and 30 wt.%. The elastomers included two fluorocarbons, six acrylonitrile butadiene rubbers (NBRs), and one each of fluorosilicone, chloroprene rubber (CR), polyurethane, styrene butadiene rubber (SBR), hydrogenated NBR (HNBR), a blend of NBR and PVC (OZO), epichlorohydrin/ ethylene oxide (ECO), ethylene propylene diene monomer (EPDM), and silicone. Specimens of each elastomer were immersed in the test fuels for a period of 4 weeks and measured for property change. Afterwards they were dried at 60°C for 20 h and remeasured. The results showed that the dioxolanes were suitable with many of the elastomers and that the performances were essentially the same for both molecules. The dioxolanes were found to either have negligible impact beyond neat diesel or they produced a small increase in swell. This minimal impact is attributed to the fact that the solubility parameters (especially those associated with polarity and hydrogen bonding) of the dioxolanes are similar to those of diesel. As a result, little change in solubility and hence swell occurred when dioxolane was added to the diesel.

The major societal problem of polymeric waste necessitates new approaches to break down especially challenging discarded waste streams. Gamma radiation was utilized in conjunction with varying solvent environments in an attempt to discern the efficacy of radiolysis as a tool for the deliberate degradation of model network polyesters. Our EPR results demonstrated that gamma radiolysis of neat resin and in the presence of four widely used solvents induces glycosidic scissions on the backbone of the polyester chains. EPR results clearly show the formation of alkoxy radicals and C-centered radicals as primary intermediate radiolytic products. Despite the protective role of the phenyl groups on the backbone of the radiation-induced polyester chains, the radiolytic-glycosidic scissions predominate. Among the following three solvents used in this study (water, isopropyl alcohol, and dichloromethane), the highest radiolytic yield of glycosidic scission was achieved using water. The •OH radicals produced in the radiolysis of phenyl unsaturated polyester aqueous suspensions very rapidly abstract H atoms from the methylene group, which is followed by a very rapid glycosidic scission. The lowest glycosidic yield was found in the dichloromethane solutions of these polyester resins due to scavenging by the fast electron capture reactions.

The compatibility of 11 bioderivable diesel blendstocks with 17 elastomer materials common to fuel storage, dispensing, and delivery systems was evaluated though volume and hardness measurements. The blendstocks included two alcohols (1-octanol and 1-nonanol), two acid esters (methyl decanoate and hexyl hexanoate), tri(propylene glycol) methyl ether (TPM), butylcyclohexane, two ketones (2-nonanone and 2-pentanone), biodiesel, and renewable diesel. Each blendstock was blended with diesel in concentrations of 0, 10, 20, and 30 wt %. The elastomers included two fluorocarbons, six acrylonitrile butadiene rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, styrene butadiene rubber (SBR), hydrogenated acrylonitrile butadiene rubber (HNBR), a blend of NBR and PVC (OZO), epichlorohydrin/ethylene oxide (ECO), ethylene propylene diene monomer (EPDM), and silicone. Specimens of each elastomer material were immersed in the test fuels for a period of 4 weeks and measured for volume and hardness. Afterward, they were dried at 60 degrees C for 20 h and remeasured. The results showed that the alkanes, esters, and alcohols were suitable with many of the elastomers. For some materials, such as neoprene, these blendstocks improved the compatibility compared to neat diesel. In contrast, the ketones and TPM produced unsuitable volume expansion (>30%) and softening in many of the elastomers including the high-performance fluoroelastomers. Analysis of the results showed that the swelling behavior is predominantly due to polarity of the elastomer and test fuels.

Our previous studies indicated that the uranium adsorption from seawater can be significantly enhanced by dropping the V/U ratio. Four different kinds of amidoxime-based adsorbents were prepared by grafting acrylonitrile along with 2-hydroxyethyl acrylate (HEA) or itaconic acid (AF8) onto polyethylene (PE) matrix through radiation-induced graft polymerization (RIGP) approach. Conversion reaction parameters of the attached nitrile functional groups (-CN) into amidoxime moieties were optimized by variation of reaction time, temperature, and solution type. FTIR and 13 C CP/MAS NMR spectra confirmed the generation of open chain amidoxime and cyclic imide dioxime by conversion of -CN. These studies also indicated significant hydrolysis of grafted HEA upon amidoximation. The braided AF8 adsorbents that were amidoximated in Water-Methanol (50:50 w/w) at 80 ºC for 3 days had an average uranium adsorption capacity of 4.44 ± 0.28 g-U/Kg-ads. after 56 days of exposure in natural seawater, with a V/U (g/g) ratio of only 1.24 ± 0.01. The new HEAEC/F18/80/12/PB adsorbent, evaluated for uranium adsorption capacity and adsorption kinetics in seawater, emerged as very promising for a lower V/U ratio. Seawater exposure for 55 days of the HEAEC/F18/80/12/PB adsorbent resulted in a uranium uptake of 3.40 ± 0.63 g-U/Kg-ads. and V/U (g/g) ratio less than one.

A polymer fiber-based adsorbent (AF1) composed of acrylonitrile and itaconic acid functional groups was synthesized by a radiation-induced graft polymerization technique onto hollow-gear shaped polyethylene (PE) fibers. Investigation of the optimum reaction parameters for the conversion of grafted cyano moieties into amidoxime groups was conducted by the reaction with hydroxylamine at different temperatures and periods in a variety of aqueous and organic solvents. The C-13 CP/MAS spectra of amidoximated AF1 adsorbent fibers from water-methanol and dimethyl sulfoxide (DMSO) revealed that both the cyclic imide dioxime and open-chain amidoxime were formed through the reaction. The conversion from amidoxime to imide dioxime was found to occur slowly and gradually with the increasing reaction time. The quicker diffusion of DMSO as compared to that of water-methanol, in the grafted trunk PE fiber, resulted in faster kinetics of the amidoximation reaction. The uranium adsorption capacity of the amidoximated AF1 samples was determined after (i) 24 h contact with sodium-based brine spiked with uranium and (ii) 56 days of exposure to filtered seawater (Sequim Bay, WA, USA) in flow-through columns. The uranium extraction performance of the adsorbents after exposure to filtered seawater was consistent with the laboratory screening results, and the amidoximated AF1 samples (in DMSO at 70 degrees C for 3 h) exhibited the highest 56 day uranium adsorption capacity (5.04 +/- 0.15 g U/kg-ads) with faster adsorption kinetics compared to the pristine AF1 adsorbents.

The compatibility of seventeen elastomer materials with two heavy biofuels (fast pyrolysis bio-oil and hydrothermal liquefaction (HTL) bio-crude) and diesel was assessed through volume change measurements. The elastomers included two fluorocarbons, six acrylonitrile rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, silicone, epichlorohydrin rubber (ECO), a blend of polyvinyl chloride and NBR (OZO), styrene butadiene rubber (SBR), hydrogenated NBR (HNBR) and ethylene propylene diene monomer (EPDM). The specimens were immersed in each test fuel for four weeks at 50°C and then measured for volume change. Afterwards, the specimens were dried, and the volume was remeasured. In general, the bio-oil produced unacceptable swelling in the fluoroelastomers, ECO, OZO, neoprene, polyurethane, SBR, HNBR, EPDM, silicone and five of the NBRs. In most cases, the HTL bio-crude produced lower (though still unacceptable) swelling than the bio-oil. Materials that showed good compatibility with the HTL biocrude were the fluoroelastomers, OZO, and silicone.

Acrylic fiber can be chemically converted to an amidoxime and carboxylate containing chelating adsorbent by a two-step synthesis method for extraction of uranium from seawater. A portion of the nitrile groups in the fiber is first converted to amidoxime using hydroxylamine followed by conversion of another portion of the nitrile groups to carboxylate with NaOH. At an optimized ratio of amidoxime/carboxylate (about 1 : 1), the chelating fiber in real seawater shows a higher uranium adsorption capacity and shorter saturation time compared with similar high-surface-area chelating fibers developed recently using a radiation-induced grafting method. The saturation capacity of uranium is estimated to be 7.73 grams per kilogram of the adsorbent at 20 degrees C and the half-saturation time is about 15.7 days. The fiber shows a vanadium/uranium ratio of about 1 in real seawater tests. The low vanadium adsorption capacity of the fiber is attributed to the branched-chain amidoxime groups formed by the specified amidoximation process. This simple and low-cost synthesis method can be scaled up to mass produce the chelating fiber for recovering metals from various aquatic environments including production of uranium from seawater.

The compatibilities of fuel system elastomers and plastics were evaluated for test fuels containing 16 vol.% isobutanol (iBu16) and 10 vol.% ethanol (E10). Elastomers included two fluorocarbons, four acrylonitrile butadiene rubbers (NBRs), and one type of fluorosilicone, neoprene, and epichlorohydrin/ethylene oxide. Plastic materials included four nylon grades, three polyamides, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), high-density polyethylene (HDPE), polybutylene terephthalate (PBT), polyoxymethylene (POM), flexible polyvinylchloride (PVC), polyetherimide (PEI), polyetheretherketone (PEEK), and a phenol formaldehyde reinforced with glass fiber (GFPF). For each polymer material, the volume, mass, and hardness were measured before and after drying. Dynamic mechanical analysis (DMA) measurements were also performed on the dried specimens. For the elastomer materials the measured properties were similar for both fuels. The fluorocarbons and fluorosilicone swelled the least (-20%), while more moderate (20-45%) expansion occurred for the two NBR hose grades and (ECO). HNBR, neoprene, and silicone exhibited high swelling and softening, which likely precludes their use in many fuel systems. For the plastic materials, the observed swell was low; Nylon 11 swelled around 15%, but otherwise, their measured swell was <10%. Many of the plastics also showed sensitivity to alcohol type, as the E10 test fuel often imparted appreciably higher swell than iBul6. In general, the plastic materials showed good compatibility with the iBu16 and E10 test fuels. The sole exception was the PVC material, which was structurally degraded from exposure to either fuel type. Compositional analysis showed high fuel retention in Nylon 12 and PVC. PVC also experienced a significant reduction in plasticizer compounds following exposure, which resulted in embrittlement and an increase in the glass-to-rubber transition temperature.

The compatibility of key infrastructure elastomers with five ketone molecules was assessed via solubility studies and volume swell measurements. The elastomer materials included two fluorocarbons, six acrylonitrile butadiene rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, styrene butadiene rubber (SBR), and silicone. The ketone molecules included acetone, 2-butanone, 2-pentanone, 2-nonanone, and cyclopentanone. The ketones were added to gasoline containing 10% ethanol (E10) and a blendstock for oxygenate blending (BOB) in levels ranging from 0% to 30% by volume. The elastomers were exposed for 4 weeks in each test fluid. The solubility was modeled using Hansen solubility parameters and the volume change was determined for each material and test fuel. In general, the volume swell increased with ketone content and corresponded well to the predicted solubilities. In most cases, the highest level of swelling occurred with added cyclopentanone and acetone, while 2-nonanone produced the lowest levels of volume expansion. The chain length of the straight ketones was found to affect the volume swell behavior as volume expansion decreased with increasing chain length. This behavior is attributed to the reduction in polarity and hydrogen bonding with chain length. Neoprene, SBR, and silicone exhibited poor compatibility with the ketone molecules at all blend levels. Fluorocarbon and fluorosilicone also showed poor compatibility but may be suitable for use as static seals in very low blend levels with 2-nonanone. The results were more mixed for polyurethane and the NBRs. In general, better compatibility (low volume swell) was observed for mixtures containing BOB than for E10. This is due to the lower polarity and hydrogen bonding of the BOB.

Polyoxymethylene dimethyl ethers (PODEs) have shown promise as candidates for diesel fuel blendstocks due to their low sooting tendency, high cetane number, and diesel-comparable boiling point range. However, there is a lack of literature regarding compatibility of PODEs with common automotive elastomers, which would be a prerequisite to their adoption into the marketplace. To address this need, an exposure study and complementary solubility analysis were undertaken. A commercially available blend of PODEs with polymerization degree ranging from 3 to 6 was blended with diesel certification fuel at 0, 33, 50, 67, at 100% by mass. Elastomer coupons were exposed to the various blends for a period of 4 weeks and evaluated for volume swell. The elastomer materials included multiple fluoroelastomers (Viton and fluorosilicone) and acrylonitrile butadiene rubbers (NBR), as well as neoprene, polyurethane, epichlorohydrin (ECO), PVC-nitrile blend (OZO), ethylene propylene diene monomer (EPDM), styrene-butadiene rubber (SBR), and silicone. The exposure results indicated overall poor compatibility for PODE, with every elastomer except for fluorosilicone exhibiting greater than 30% volume swell at the 33% blend level. The general trend across the elastomers was either a consistent increase in volume swell with PODE concentration, or maximum in volume swell at an intermediate blend fraction. One notable exception is EPDM, which is not generally compatible with diesel fuel and which exhibited a reduction in volume swell with increasing PODE concentration. The same elastomers and PODE/diesel blends were evaluated using Hansen solubility parameter analysis, which predicted similar trends to the exposure study with the exception of ECO. From these results, we conclude that adoption of PODEs as a diesel fuel blendstock will require either the development of specialized elastomers, or that the blend fraction be kept to a low level to maintain compatibility with existing elastomers. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Electron beam curing is demonstrated as a promising method for high speed, low cost and environmentally friendly battery electrode manufacturing. This work reports transfer of this process to pilot scale equipment and evaluation of electrochemical performance in prototype 1.5 Ah pouch cells. Thick LiNi0.5Mn0.3Co0.2O2 (NMC532) composite electrodes with an areal loading of 25 mg cm(-2) (similar to 4 mAh cm(-2)) are successfully cured at a line speed of 500 feet per minute at 275 keV. Compared to the NMC532 cathode processed via a conventional coating method, the electron beam cured electrodes show higher capacity fade in the first 100 cycles, but similar fade rate afterwards. Further improvement strategies are proposed and discussed. This work demonstrates that electron beam curing is a promising method for manufacturing thick battery electrodes at high speeds and low capital/operation cost. (C) 2019, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

The compatibility of four potential bio-derived blendstock molecules with infrastructure elastomers was determined by measuring the volume change following exposure. The blendstock molecules included 1-propanol, diisobutylene, cyclopentanone, and a furan mixture. The elastomers included two fluorocarbons, six nitrile rubbers (NBRs), and one each of fluorosilicone, neoprene, polyurethane, and silicone. The elastomers were exposed to the fuel molecules as blends ranging from 0 to 30 vol.% in both a blendstock for oxygenate blending (BOB) formulation and an E10 fuel. Silicone exhibited excessive swelling in each test fuel, while the other elastomers showed good compatibility (low swell) with diisobutylene, 1-propanol, and the furan mixture when BOB was used as the base fuel. The E10 base fuel produced high (>30%) swell in neoprene, polyurethane, and some nitrile rubbers. In most cases diisobutylene produced the least amount of volume expansion. In contrast, the addition of cyclopentanone produced unacceptably high swelling in each elastomer and is not considered suitable for use with these fuels. Analysis of the results showed that the swelling behavior is predominantly due to the polarity of the elastomer and test fuels.

One critical challenge of the development of seawater uranium extraction is to make uranium adsorbents perform well in the complex real seawater matrix, which is comprised of many competing ions and natural organic substances. Here, we conducted a systematic study using a continuous-flow seawater flume system to assess the potential impacts of dissolved organic matter (DOM) and dissolved iron on the uranium uptake performance, including adsorbent reusability, of amidoxime-based adsorbents. In the 28-day exposure, the adsorbent exposed in dissolved Fe-spiked seawater (low DOM/high Fe) and humic acid-spiked seawater (high DOM/high Fe) showed lower uranium adsorption loadings (73% and 56% of adsorption loading, respectively) than the same adsorbent exposed in seawater without spiking (low DOM/low Fe). The uranium adsorption loading of the reused adsorbent (after uranium stripping by a mild bicarbonate elution) in the dissolved Fe-spiked seawater dropped substantially to only 24% of the loading in the unspiked clean seawater counterpart, while not much change was observed in the performance of the adsorbent exposed to the humic acid-spiked seawater. Fourier transform infrared signatures of adsorbents suggest that the amidoxime ligands in the adsorbent exposed to dissolved Fe-spiked seawater had more severe degradation than the adsorbents exposed to humic acid-spiked seawater and unspiked clean seawater. Unlike the adsorbent exposed to dissolved Fe-spiked seawater, the adsorbent exposed to humic acid spiked seawater did not adsorb an elevated level of Fe compared to the adsorbent in the unspiked clean seawater. This suggests that the species of Fe in the humic acid-spiked seawater (primarily humic acid bound Fe) did not interact with the amidoximebased adsorbent, while the Fe species in the Fe-spiked seawater strongly interacted with the adsorbent and caused significant degradation of amidoxime ligands. On the other hand, highly variable uranium adsorption loadings were observed in the adsorbent in contact with humic acid-spiked seawater, but not in the adsorbents exposed to dissolved Fe-spiked seawater and seawater without spiking. Our observations indicate that seawater receiving high inputs of DOM and dissolved Fe, such as coastal waters, is not ideal for efficient extraction of uranium.