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Plastic films are abundant, but seldom recycled in the United States (US). It is both economically and operationally challenging to recycle plastic films because their light weight makes accumulating material difficult. Additionally, films are not allowed in most curbside recycling programs in the US because they tangle around equipment used at material recovery facilities (MRFs) and effect a MRFs' ability to effectively sort other materials. As a result, the only recycling pathway for post-consumer plastic films in the US is retail return collection programs. Currently, only the most abundant type of post-consumer plastic film, polyethylene (PE), is accepted by these programs in the US. Although PE films come in many forms, grocery bags are the most well-known, and therefore most abundant, film in the retail return recycling stream. The New York State (NYS) Plastic Bag Waste Reduction Law prohibits the distribution of single use plastic bags. This work explored how ending the distribution of grocery bags impacted retail return recycling programs for PE films in Western New York. We show that a loss of the most recognizable and abundant PE film results in a 1.4 - 2.8x increase in contamination rates, devaluing films that are still collected. As a result, increased contamination rates may threaten the viability of this recycling pathway. The study also provides a complete speciation of this recycling stream with a novel level of detail, as existing research on this recycling pathway is limited.

Lake Erie experiences annual harmful algal blooms (HAB), but generated HAB biomass may provide a waste-based precursor for environmental remediation materials. Three classes of materials (i.e., algal powder biosorbent, porous carbon, and iron/carbon (Fe/C) composite) are prepared from HAB biomass. Algal powder is nonporous with diverse functional groups. Porous carbon, prepared via one-pot carbonization and activation, has surface area up to 430 m2/g. Fe/Cs are prepared by cultivating HAB biomass in iron-rich media, followed by one-pot pyrolysis. Fe/Cs have over 6 wt% iron (Fe0 and Fe3O4) and nitrogen doping (up to 4 wt%). Materials were applied in phenol and Cr(VI) removal tests to identify preferred products for use in water treatment applications. In deionized water, porous carbon removes the most phenol (52 mg/g), followed by algal powder (38 mg/g) and Fe/C (33 mg/g). Micropore volume and functional groups improve phenol removal. Cr(VI) removal follows: Fe/C (43 mg/g) > porous carbon (28 mg/g) > algal powder (17 mg/g), with synergistic adsorption and reduction elevating Fe/C’s performance. Cr(VI) and phenol removal studies were completed with variable pH, ionic strength, and water composition to highlight application potential. This work proposes HAB biomass reuse for pollution control, investigating interaction mechanisms between materials and contaminants.

Microporous and hydrophobic polymers were synthesized and tested as NO oxidation catalysts to overcome water co-adsorption in combustion flue gas streams. The self-cross-linked 4,4′-bis(chloromethyl)-1,1′-biphenyl polymer (PBCMBP), with micropore volume of 0.38 cm3/g and surface area of 1430 m2/g, provided 62% NO oxidation efficiency at 25 °C in dry conditions but its performance dropped to 50% in the presence of 1.6 vol% moisture (wet conditions). To decrease performance loss, PBCMBP was modified with benzene (PBCMBP-BZ) to remove pendant chloromethyl groups, improving resistance to surface reactions with NO2 that add hydrophilicity. In wet conditions, PBCMBP-BZ has 59% NO oxidation efficiency, an 18% increase compared to PBCMBP at 25 °C. PBCMBP was also functionalized with dimethylamine (PBCMBP-DMA) to increase surface basicity, increasing NO oxidation by 11% in dry conditions, but decreasing NO oxidation in wet conditions by 30% due to increased proclivity to react with NO2. The combined impact of temperature and humidity was measured up to 100 °C, showing that moisture’s impact decreases with increasing temperature and that PBCMBP-DMA outperforms other catalysts at higher temperatures. Findings suggest that catalyst surface chemistry can be manipulated to further improve NO oxidation performance, especially in the presence of moisture.

It is important to develop new materials/methods to remove NO from gas streams to protect the environment. Use of porous materials to catalytically convert NO to NO2 may improve existing NOx control technologies. In this work, three porous materials (i.e., activated carbon fiber cloths (ACFCs), zeolites, and metal-organic frameworks (MOFs)) were evaluated as NO oxidation catalysts at 25 °C. Maximum included sphere diameter (Di) between 5.5 and 11.0 A is shown to result in higher steady-state NO conversion (23%−71.5 ± 2.5%) by providing appropriate channels/cages that accommodate and stabilize the first transition state (TS1) through van der Waals interactions. For all considered catalysts but MIL-53 (Al), steady-state NO conversion initially increases, then decreases, with increasing pore volume contributed by Di (5.5–11.0 A). Maximum free sphere diameter (Dmax) for the selected catalysts with steady-state NO conversion between 23% and 71 ± 2.5% is between 3.7 and 9.0 A, allowing transport of reactants and products. Extra-framework cations (H+, NH4+, and Na+) and coordinatively unsaturated sites (Cu2+, Fe3+, and Cr3+) increase steady-state NO conversion by providing TS1 stabilization through electrostatic and coordinative interactions, respectively. However, appropriate Di and Dmax values are identified as the most influential variables for steady-state NO conversion using these catalysts. For NO conversion in the presence of SO2, no impact is observed for steady-state NO conversion of a MOF sample, but decreases of 100% and 36% for ACFC and zeolite samples, respectively. These results provide direction for designing NO oxidation catalysts to improve steady-state NO conversion.

Solid fuel combustion remains a dominant energy source for household heating and cooking in less developed countries. As a result, almost three billion people are exposed to household air pollution, causing four million premature deaths annually, primarily among poor women and children. We analyze data from Demographic and Health Surveys in 69 countries to identify determinants of transition from solid to cleaner fuel. Estimates from a population-averaged linear model show that population density and size, rural population share, income inequality, and charcoal production are positively associated with countries’ solid fuel use, while GDP per capita, electricity and natural gas production have the opposite effect. Economic development, measured as GDP per capita, has the strongest link to solid fuel use: a standard deviation increase in per capita GDP above its mean reduces solid fuel use from 70% to 57% of households. Electricity production is another strong predictor: solid fuel use drops by 11% when electricity production increases by one standard deviation above the mean. In addition, in a fixed-effects linear model, population size has a positive association with solid fuel use, while increases in GDP per capita and the number of governments’ renewable energy incentives are associated with lower dependence on solid fuels.

Nitrogen-doped porous carbon spheres impregnated with iron nanoparticles (Fe/C-N) are prepared from glycerol, a by-product of the biodiesel industry, and ferric ammonium citrate (FAC) via ultrasonic spray pyrolysis (USP). Carbon microspheres are generated during rapid (

Iron/carbon (Fe/C) composites efficiently remove Cr(VI) because of synergistic adsorption and reduction effects. This study uses harmful algal bloom (HAB) biomass and ferric ammonium citrate (FAC) or ferric nitrate as precursors for preparing Fe/Cs with a one-pot synthesis. The investigation uniquely differentiates material and performance impacts associated with two iron loading approaches, bioaccumulation (metal uptake by living algae), and biosorption (metal deposition onto dry algae). As-prepared Fe/Cs are up to 70% mesoporous with iron loading reaching 8.3 wt %. Uniformly dispersed nanoparticles (20–50 nm) are observed in all Fe/Cs, and microscale particles are present on the surface of biosorption samples due to sintering. Fe3O4 is the dominant iron species in Fe (NO3)3 added samples, while Fe0 dominates samples prepared with FAC, attributed to the reducing atmosphere generated during FAC pyrolysis. Up to 4.0 wt % nitrogen doping is achieved, from nitrogen in HAB biomass and iron precursors. Fe/Cs r...

Wet flue gas desulfurization (WFGD) simultaneously removes Hg and SO2 from coal-fired power plant flue gas streams. Hg0 re-emission occurs when the dissolved Hg(II) is converted to a volatile form (i.e., Hg0) that can be subsequently emitted into the ambient air from WFGD wastewater aeration basins. Others have shown that Hg0 re-emission depends on pH, temperature, ligands (Cl, Br, I, F, SO32-, SO42-, NO3-, SCN-, and ClO-), O2, minerals (Se and As), and metals (Fe and Cu) in WFGD wastewater. Still others have shown Hg0 re-emission restriction via inhibitor addition (adsorbents and precipitators). This is the first review that summarizes the complex and inconsistently reported Hg0 re-emission mechanisms, updates misconceptions related to Hg(II) complexation and reduction, and reviews applications of inhibitors that convert aqueous Hg(II) into stable solid forms to prevent gaseous Hg0 formation and release.

Environmental DNA (eDNA) analysis is gaining prominence as a tool for species and biodiversity monitoring in aquatic environments. eDNA shed by organisms is captured in grab samples, concentrated by filtration, extracted, and analyzed using molecular methods. Conventional capture and filtration methods are limited because (1) filtration does not capture all extracellular DNA, (2) eDNA can degrade during sample transport and storage, (3) filters often clog in turbid waters, reducing the eDNA captured, and (4) grab samples are time sensitive due to pulse eDNA inputs. To address these limitations, this work designs and validates Passive Environmental DNA Samplers (PEDS). PEDS consist of an adsorbent-filled sachet that is suspended in water to collect eDNA over time. Both extracellular and cellular DNA are captured, and the extracellular DNA is protected from degradation. The eDNA captured over time may be more representative than a grab sample. Two adsorbents, Montmorillonite Clay (MC) and Granular Activated Carbon (GAC), are tested. In laboratory experiments, MC-PEDS adsorbed five times more extracellular DNA and desorbed up to four times more than GAC-PEDS (despite high levels of eDNA loss during desorption). In microcosm and field experiments, GAC-PEDS captured over an order of magnitude more eDNA than MC-PEDS. Field results further validated PEDS as an effective eDNA capture method compared to conventional methods.

Spinal solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a rare mesenchymal malignancy. Radiographically, SFT/HPCs have a mutable appearance, with irregular borders, heterogeneous contrast enhancement, and variable but frequently hypointense T2 signal. We report a series of 5 neurosurgically managed spinal SFT/HPCs treated at our institution, with particular attention to 3 lesions demonstrating marked T2-hypointensity and differential diagnosis for the unusual finding of a “T2 dark” spinal lesion. Retrospective chart review of prospectively maintained surgical database, queried by diagnosis and site codes, 2002–2017. Retrospective radiographic review, with initial screening via keyword search of MR reports for “T2” and “hypointense.” Four primary and one metastatic spinal SFT/HPCs were operatively treated during the study period (median follow-up 12 months; range 10–92). Three demonstrated marked T2 hypointensity on preoperative MRI, underwent primary resection—GTR in two, STR in one—and have remained progression-free on routine postoperative surveillance. Two patients with isointense lesions recurred within the follow-up period. Radiographic review identified a host of predominantly rare T2-hypointense lesions, including arteriovenous malformation, disk fragmentations, calcific arachnoiditis, calcifying pseudoneoplasm of the neuraxis, cavernoma, cord hemorrhage/acute blood, desmoid, granulocytic sarcoma, pigmented villonodular synovitis, Edheim-Chester, extramedullary hematopoiesis, IgG4-negative inflammatory pseudotumor, idiopathic hypertrophic pachymeningitis, B-cell lymphoma, primary melanoma neoplasm, melanotic schwannoma, meningioma, opacification of the posterior longitudinal ligament, osteoblastoma, osteochondroma, osteosarcoma, and synovial cyst. T2 hypointensity is associated with SFT/HPC, and may be an indicator relative indolence. “Dark” T2 spinal lesions are rare, with a narrow differential populated predominantly by rare entities.

Self-cross-linked 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP) polymers with tailored pore size distribution (PSD) and average pore width (Wavg) were synthesized via the Friedel-Crafts reaction in 1,2-dichloroethane (DCE) with reactive (benzene) or non-reactive (hexane and cyclohexane) co-solvents. Compared to using only DCE, Wavg increases (up to 450%) with increasing benzene:DCE ratio due to decreases in cross-linking degree. Hexane and cyclohexane induce phase separation and co-solvent trapping in developing polymers, changing PSD and Wavg without altering cross-linking degree. Findings provide a simple technique to synthesize hyper-cross-linked polymers with user-defined PSDs.

Resistive heating or electrothermal regeneration is a valuable alternative to conventional adsorbent regeneration methods because of cost, energy, and time efficiency; however, it only works for electrically conductive adsorbents such as activated carbon. Zeolites are widely used adsorbents for gas separation; however their high resistivity prevents their regeneration with resistive heating. This paper describes a proof of concept study assessing the feasibility and performance of multiple carbon loading techniques to decrease zeolite resistivity and allow its resistive heating without sacrificing its adsorption properties. Carbon was added to zeolite by physical mixing, chemical vapor deposition of ethanol and benzene, carbon nanotube growth via catalytic CH4 decomposition, and thermal decomposition of polyvinyl-alcohol. Similar thermal conditions were applied (2 hours at 600 °C) for all carbon deposition methods to avoid the impact of multiple variables. Elemental analyses and scanning electron micrographs confirmed the addition of carbon, and resistivity decreased by up to 8 orders of magnitude. Resistivity decrease was greatest when carbon was added directly to the zeolite's surface compared to physical mixing with zeolite. Carbon nanotube growth decreased zeolite resistivity from >107 Ω m to 0.7 Ω m, but caused partial loss of adsorption capacity. The reduction in zeolite resistivity, however, allowed resistive heating of zeolite at a heating rate as high as 120 °C min−1. This work presents CNT-addition as a potential method to allow resistive heating for zeolite adsorbent regeneration. By considering multiple carbon addition methods and identifying CNT-addition as preferred, these findings inform future research efforts that will focus on optimization and application testing.

Styrenic polymers (XAD2 and XAD4) were hyper-cross-linked using dichloroalkane (-methane, -ethane, -butane, and -hexane) cross-linkers in the presence of a Friedel-Crafts catalyst (FeCl 3 ). Hyper-cross-linking with dichloromethane generated the largest micropore volume increase; surface area and micropore volume decreased with increasing cross-linker length. Longer dichloroalkane cross-linkers also generated more hydrophobic polymers with less bulk oxygen content. Despite this variability, at 90% relative humidity, polymers directly hyper-cross-linked with dichloroalkanes consistently adsorb >80% less water than polymers hyper-cross-linked via chloromethylation. Results demonstrate an opportunity to add micropores needed for adsorption applications without sacrificing the polymer's unique, and often advantageous, hydrophobicity. Given that industrial adsorbate streams often contain moisture, this work is important because it provides a method that allows polymers to remain hydrophobic after hyper-cross-linking, making them competitive for industrial use.

This research investigates the effect of adsorbent bed configuration on volatile organic compounds (VOCs) adsorption with beaded activated carbon (BAC). Five-cycle adsorption/desorption tests using a single VOC (1,2,4-trimethylbenzene) and a mixture of nine VOCs were completed using fixed and fluidized bed adsorber configurations. Adsorption tests were completed with full loading of the adsorbent. All regeneration tests were completed in the fixed bed arrangement. The adsorption capacity of the BAC was not affected by the adsorption bed’s configuration in case of reaching full breakthrough. For the VOC mixture, however, 30% less heel buildup was observed for the fluidized bed configuration. Higher accumulation of heavy adsorbates was found in fixed bed as opposed to fluidized bed, explaining the higher heel buildup in the former. On the other hand, improved mass transfer was found across the entire fluidized bed as a result of better gas-particle contact. These results show that, besides the expected engi...

In this work, amine-impregnated activated carbon was prepared from oil sands coke, for use in CO2 capture. Delayed oil sands coke was activated using microwave heating and KOH as activation agent. The resulting material was then impregnated with one of diethanolamine, methyl diethanolamine, or tetraethylene pentamine. Analysis of the bulk and surface composition of the impregnated samples using elemental analysis and X-ray photoelectron spectroscopy suggested that the amines were deposited on the surface of the activated carbon. Materials impregnated with diethanolamine performed best for CO2 capture; the highest adsorption capacity achieved was 5.63 mmol CO2/g adsorbent for activated carbon impregnated with 1.15 mmol N/g activated carbon—nearly 75% higher than reported values for zeolite 13X. Adsorption of CO2 on the amine-impregnated activated carbon at 40, 50, 60, and 75 °C showed that the highest adsorption capacity was obtained at 50 °C. Using oil sands delayed coke as a precursor for activated carbo...

Glycerol, a by-product of biodiesel production, was systematically investigated as a liquid precursor for activated carbon (AC). In this study, acid-mediated dehydration, polymerization, and carbonization of liquid glycerol forms solid chars with unique surface textures and compositions. For the first time, a description of the dehydration acid's role in char formation is reported, relating decomposition mechanisms of H2SO4 and H3PO4 to resulting char properties. With this understanding, chars with variable functional groups and porosities are prepared based on distinguished acid–glycerol relationships. Porosity in chars is added with rapid physical activation, generating ACs with surface areas up to 2470 m2 g−1 and pore volumes up to 1.44 cm3 g−1. By combining different dehydration acids and activation agents (steam or CO2) with controlled pyrolysis/activation conditions, intentionally tailored ACs with variable surface areas, pore widths, structural configurations, and surface chemistries are obtained. To justify use, ACs are applied for removal of gas phase volatile organic compounds (VOCs) and aqueous phase chromium (Cr(VI)), outperforming commercial ACs. Toluene, hexane, and Cr(VI) adsorption capacities as high as 1.5 g g−1, 1.1 g g−1, and 56 mg g−1, respectively, are reported. Overall, glycerol is used to prepare AC with high and tuned porosity, and a facile method for producing tailored ACs from a liquid industrial waste is introduced.

Selective metal removal from aqueous samples has wide-spanning environmental applications as well as implications in precious or rare metal recycling. In this work, a heterologous biosynthetic system was used to produce the natural product yersiniabactin (Ybt) for incorporation into a metal removal water treatment operation. Specifically, Ybt was adsorbed to resin within a packed-bed column prototype to continuously remove copper from water samples with results that included: 1) >80% removal capability; 2) variation in removal across pH levels, providing an opportunity for in situ resin regeneration and metal recovery; 3) selective removal from a copper-zinc mixture; and 4) application to environmental field water samples. In summary, the combined biosynthetic and recovery processes offer an alternative opportunity for selective removal of copper and other metals contaminating water samples.

Rapid increases in biodiesel use results in a surplus of its production by-product, glycerol, exceeding demand by traditional applications. In this study, Fe/C composites are prepared from glycerol-based precursors that include a dissolved iron salt via one-pot, two-stage pyrolysis. The first heating stage dehydrates, polymerizes, and carbonizes glycerol via acid-assisted pyrolysis while homogeneously dispersing a precipitated iron salt throughout the generated carbon matrix. The second stage develops porosity in the carbon support while reducing impregnated iron nanoparticles. Carbon supports with tailored physiochemical properties are generated by varying the dehydration acid (H2SO4 or H3PO4). Fe/C samples are predominantly mesoporous, with specific surface areas up to 560 m2/g and bulk iron contents up to 8.9 wt%, primarily as partially reduced Fe3O4. Cr(VI) removal follows the Freundlich model, reaching 107 mg/g at pH = 5. Mesoporous Fe/C composites are magnetic, allowing collection for reuse. After 4 use/recovery/reuse cycles, performance drops by < 25% when the products are applied in an actual wastewater system. Overall, the magnetic mesoporous Fe/C composite materials are straightforward to produce from waste glycerol and exhibit potential for environmental application in aqueous systems.

The objective of this study is to determine the contribution of surface oxygen groups to irreversible adsorption (aka heel formation) during cyclic adsorption/regeneration of organic vapors commonly found in industrial systems, including vehicle-painting operations. For this purpose, three chemically modified activated carbon samples, including two oxygen-deficient (hydrogen-treated and heat-treated) and one oxygen-rich sample (nitric acid-treated) were prepared. The samples were tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds. For the different samples, mass balance cumulative heel was 14 and 20% higher for oxygen functionalized and hydrogen-treated samples, respectively, relative to heat-treated sample. Thermal analysis results showed heel formation due to physisorption for the oxygen-deficient samples, and weakened physisorption combined with chemisorption for the oxygen-rich sample. Chemisorption was attributed to consumption of surface oxygen groups by adsorbed species, resulting in formation of high boiling point oxidation byproducts or bonding between the adsorbates and the surface groups. Pore size distributions indicated that different pore sizes contributed to heel formation - narrow micropores (

The effect of activated carbon's pore size distribution (PSD) on heel formation during adsorption of organic vapors was investigated. Five commercially available beaded activated carbons (BAC) with varying PSDs (30-88% microporous) were investigated. Virgin samples had similar elemental compositions but different PSDs, which allowed for isolating the contribution of carbon's microporosity to heel formation. Heel formation was linearly correlated (R(2)=0.91) with BAC micropore volume; heel for the BAC with the lowest micropore volume was 20% lower than the BAC with the highest micropore volume. Meanwhile, first cycle adsorption capacities and breakthrough times correlated linearly (R(2)=0.87 and 0.93, respectively) with BAC total pore volume. Micropore volume reduction for all BACs confirmed that heel accumulation takes place in the highest energy pores. Overall, these results show that a greater portion of adsorbed species are converted into heel on highly microporous adsorbents due to higher share of high energy adsorption sites in their structure. This differs from mesoporous adsorbents (low microporosity) in which large pores contribute to adsorption but not to heel formation, resulting in longer adsorbent lifetime. Thus, activated carbon with high adsorption capacity and high mesopore fraction is particularly desirable for organic vapor application involving extended adsorption/regeneration cycling.

The effect of desorption purge gas oxygen content on activated carbon performance, specifically irreversible adsorption, was investigated. Beaded activated carbon (BAC) was tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds representing industrially-relevant organic groups. Different concentrations of oxygen (≤5–10,000 ppm) were used in the N2 desorption purge gas. With increasing O2 concentration, mass balance cumulative heel increased by up to 35% and the fifth cycle adsorption capacity decreased by up to 55% relative to baseline scenario (≤5 ppm O2 in N2). Derivative thermogravimetric analysis showed heel formation due to physisorption for ≤5 ppm O2 and a combination of physisorption and chemisorption for other samples, indicating that with increasing oxygen concentration, compounds that would be physically adsorbed in highly pure N2, may instead undergo chemical reactions and become chemisorbed. Micropore surface analysis indicated increased diffusion resistance in samples regenerated in ≥625 ppm O2, likely associated with chemisorbed species. BAC samples exposed to 50 successive adsorption/regeneration cycles showed trends consistent with short-term exposure (5 cycles). The results may identify suitable purge gas purity for industrial use and explain the relationship between heel formation and purge gas purity.

Heel formation on three activated carbon fiber cloths (ACFC10, ACFC15, and ACFC20, with increasing pore widths and volumes) was assessed after cyclic adsorption/resistive heating regeneration using 1,2,4-trimethylbenzene (TMB). Following regeneration at 288 °C, cumulative heel for ACFC10, ACFC15, and ACFC20 was 3.5 wt%, 4.1 wt%, and 4.2 wt%, respectively. Adsorption capacity of ACFC10; however, dropped by 83% compared to only 9% and 5% for ACFC15 and ACFC20, respectively. To prevent these capacity losses, regeneration temperature was increased to 400 °C. However, this increased cumulative heel and adsorption capacity losses to 3.7 wt% and 93% (ACFC10), 10.4 wt% and 51% (ACFC15), and 18.9 wt% and 50% (ACFC20), respectively. It is proposed that these observations results from carbon deposition due to thermal degradation of TMB during regeneration and rapid adsorbent heating. Increasing regeneration temperature enhances the endothermic decomposition processes, increasing heel buildup. Because the pores in ACFC10 are narrower than in ACFC15 and ACFC20, even small amounts of heel obstruct ACFC10's pores, explaining its notably larger decrease in adsorption capacity. These results suggest that rapid heating could be associated with reduced adsorbent performance. Regeneration conditions could be optimized to allow fast desorption with minimal adsorbate decomposition.

Understanding phenol adsorption-desorption mechanisms allows adsorbent tailoring to improve capacity and adsorbent reuse. Amberlite™ XAD4, a commercial styrenic polymer that is convenient to physically and chemically modify, was functionalized with dimethylamine (DMA) or trimethylamine (TMA) and/or hyper-cross-linked with 1,2-dichloroethane. These modifications were applied to enhance individual and/or synergistic phenol adsorption mechanisms, including hydrogen bonding, electrostatic interactions, and π-π dispersion forces. While XAD4-DMA adsorbs more phenol at pH = 6, XAD4-TMA has 23% higher capacity at pH = 11 due to adsorbate deprotonation that increases electrostatic interactions. Combining hyper-cross-linking with amination maximizes adsorption capacity due to synergistic impacts associated with increased micropore volume and surface affinity. Amine groups reduce desorption efficiency by 6-94% due to stronger adsorbate-adsorbent interactions compared to π-π dispersion forces. Isobutanol, which forms hydrogen bonds, is the most efficient desorption solvent, followed by chloroform, which has the same polarity index but does not hydrogen bond. n-Hexane only desorbs phenol removed with π-π dispersion forces and is not appropriate to regenerate aminated polymers. 0.1 N NaOH is an environmentally benign solvent for regenerating as-received XAD4 and XAD4-DMA, but not XAD4-TMA. Understanding phenol adsorption mechanisms allows development of physiochemically modified polymers with increased phenol adsorption capacity and regeneration efficiency.

Iron nanoparticles (Fe NPs) are used for treating water contaminated with metals or organic compounds. One-dimensional (1-D) carbon nanotubes (CNTs) and two-dimensional (2-D) graphenes act as useful nanocarbon (NC) supports for Fe NPs by resisting aggregation and enhancing adsorption and redox activity. However, no study showed how shape difference between tubular CNT and planar graphene structures dictates the physicochemical properties and pollutant removal potential of their iron-based nanohybrids. In this work, ultrasonic spray pyrolysis was used to continuously prepare Fe-CNT and Fe-rGO nanohybrids. Both NC shape and Fe/NC ratio influenced Fe NP size, loading, and oxidation states. High Fe content (precursor Fe/NC mass ratio = 2) resulted Fe NPs with diameters of 30.97 ± 7.00 and 24.11 ± 4.42 nm for Fe-CNT and Fe-rGO, respectively; however, low Fe content (Fe/NC = 0.2) provided more uniformly dispersed Fe NPs of 15.65 ± 3.06 and 9.67 ± 1.49 nm, respectively, while unsupported Fe NPs were 285.71 ± 132.42 nm. The USP-derived nanohybrids, for the first time, were used for removal of pollutant, i.e., chromium (Cr(VI)) from aqueous media. Both CNT and rGO provided synergistic effects to significantly enhance Fe NPs’ ability to remove Cr(VI); the effect was more pronounced in Fe-rGO than Fe-CNT and also for low Fe content in both cases. Fe-rGO with low Fe/NC ratio and smallest Fe NPs provided the highest Cr(VI) removal capacity (25 mg/g), which was a multifold improvement over bare Fe NPs and other synthesized nanohybrids (range 7–14 mg/g). Overall, 2-D rGO improved contaminant removal capacity of the nanohybrids more than 1-D CNT indicating towards shape effect of NC supports.

Anthropogenic NO x emissions from stationary sources to the atmosphere continue to be of concern because of their adverse effects on public health and the environment. An alternative method to conventional selective catalytic reduction to reduce the amount of NO x emissions is oxidation of NO to more soluble NO 2 upstream of an absorption device. Zeolites and activated carbon are effective NO oxidation catalysts, but their oxidation mechanisms are not fully understood. Here, zeolites were evaluated as NO oxidation catalysts experimentally and theoretically to identify preferred pore structures for NO conversion to NO 2 and to show mechanistic similarities to activated carbon fiber-catalyzed NO oxidation. For the 17 zeolites tested here, steady-state NO conversion is not related to their chemical composition (i.e., Si, Al, or P). However, similar to carbonaceous catalysts, steady-state NO conversion mainly depend on the zeolite's physical properties, including the zeolite's cage size, pore width, and pore volume. Zeolites with maximum free sphere diameter ( D max ) between 4.70 and 6.45 A, or zeolites with maximum included sphere diameter ( D i ) between 5.71 and 7.37 A, derived from experimental results, are most effective for NO oxidation to NO 2 regardless of the zeolites’ channel-to-cage ratio. A mechanism for NO oxidation proceeding through the [ONOONO] transition state (TS) is described here, challenging the reported mechanism that adsorbed C*–NO 3 species are the precursors of NO 2 formation. Void spaces with dimensions similar to or slightly larger (i.e., 7 A width) than the size of the TS (4.46 A × 4.67 A × 6.94 A, derived from TS calculations) are the most effective spaces for NO oxidation due to strengthened van der Waals interaction between the confined TS and pore walls of the zeolite. Criteria for screening effective zeolites for NO oxidation are proposed based on results for the 17 tested zeolites, and 82 of the 206 available zeolite codes are predicted to be effective with high steady-state NO conversion. Consistent physical geometries of zeolite pore sizes ( D i = 4.70–6.45 A or D max = 5.71–7.37 A) and activated carbon fiber pore widths (5–7 A) provide convincing evidence that such pore sizes are needed to provide efficient steady-state NO conversion. These results may be extended to other categories of microporous materials to choose the most appropriate material for catalytic NO conversion to NO 2 .

Objective To determine adverse event rates for adult cranial neuro-oncologic surgeries performed at a high-volume quaternary academic center and assess the impact of resident participation on perioperative complication rates. Patients and Methods All adult patients undergoing neurosurgical intervention for an intracranial neoplastic lesion between January 1, 2009, and December 31, 2013, were included. Cases were categorized as biopsy, extra-axial/skull base, intra-axial, or transsphenoidal. Complications were categorized as neurologic, medical, wound, mortality, or none and compared for patients managed by a chief resident vs a consultant neurosurgeon. Results A total of 6277 neurosurgical procedures for intracranial neoplasms were performed. After excluding radiosurgical procedures and pediatric patients, 4151 adult patients who underwent 4423 procedures were available for analysis. Complications were infrequent, with overall rates of 9.8% (435 of 4423 procedures), 1.7% (73 of 4423), and 1.4% (63 of 4423) for neurologic, medical, and wound complications, respectively. The rate of perioperative mortality was 0.3% (14 of 4423 procedures). Case performance and management by a chief resident did not negatively impact outcome. Conclusion In our large-volume brain tumor practice, rates of complications were low, and management of cases by chief residents in a semiautonomous manner did not negatively impact surgical outcomes.

We manipulate the pore size of nanoporous polymeric photonic crystals using phase change between water and ice, demonstrating accurate post-manipulation of reflection resonances and thereby providing an approach to address grand challenges in nanomanufacturing and materials engineering.

New catalysts, in particular activated carbons, are being developed to improve NO oxidation kinetics and to minimize the negative impacts of water vapor and SO 2 as an alternative NO x control strategy for flue gases. However, the literature is inconclusive about the pathway to achieve a stable downstream NO 2 concentration, creating discrepancies in the NO oxidation mechanism. In this paper, a simple two-step mechanism is proposed and justified for NO oxidation catalyzed by microporous activated carbon. In the first mechanistic step, NO is rapidly oxidized to NO 2 in activated carbon's micropores with constant NO conversion efficiency, prior to the formation of adsorbed intermediates (e.g., C * NO 2 , C * NO 3 or C * NO NO 3 ). This conclusion challenges the idea that NO oxidation to NO 2 requires decomposition of the C * NO NO 3 intermediate. Instead, we show that the physical properties of the catalyst (i.e., micropore width and volume) control steady-state NO oxidation kinetics, with carbon's chemical properties having no apparent impact for the conditions tested here. In the second mechanistic step, newly formed NO 2 is chemically adsorbed on the carbon surface, resulting in formation of NO and C N or C O complexes. Chemical disproportion of NO 2 proceeds until the carbon surface is saturated with these complexes. It follows that the first step of the mechanism (NO oxidation in micropores) controls steady state NO oxidation kinetics while the second step (NO/carbon surface reactions) controls transient NO oxidation kinetics. This two-step mechanism is confirmed via in situ cyclic experiments and NO 2 pre-adsorption tests. Pre-saturation of the carbon surface with functional groups decreases the impact of the second mechanistic step, affecting transient NO oxidation kinetics but having no impact on steady-state oxidation kinetics. A more complete understanding of the reaction mechanism allows us to better prepare tailored carbonaceous NO oxidation catalysts.

Solid fuel use is linked with adverse effects on the environment and human health. Yet, solid fuels remain an important energy source for households in developing countries. Even when country-level dependence on solid fuels is modest, there is often significant variation in within-country patterns of solid fuel use. This study examines a range of environmental and socioeconomic conditions to understand the relationship between them and household energy use within a country. While our results are derived from a study of regional patterns of solid fuel dependence in Peru, the contribution of this study is broad: variables that we include in our models of households’ fuel choice decisions are likely to shape such decisions in most developing countries. Our findings indicate that environmental conditions, such as elevation and forest cover, are associated with solid fuel use. Socioeconomic factors, including urbanization, poverty and female literacy, are similarly important. In addition, we identify nuanced links between types of female employment and indigenous population, on the one hand, and solid fuel use, on the other.

Fundamental studies describing the impact of carbon’s physical and chemical properties on NO oxidation allow for the development of catalysts tailored specifically for abating emissions of nitrogen oxides. Here, we show that acidic oxygen functional groups are developed on activated carbon fiber cloth during carbon-catalyzed NO oxidation. Reaction and thermal desorption cycle experiments demonstrate the continuous addition of oxygen to carbon as carbonyl and carboxyl functional groups. After four cycles, the oxygen content of carbon increased by 280%. There is also a 65% reduction in the time required to release NO2 from the carbon surface, allowing the reaction to achieve steady-state NO conversion 45% faster. The steady-state NO oxidation rate remains constant during the four cycles (48.5 ± 1.6 μmol/h), which is attributed to stable physical properties of carbon during the cycles. Oxygen groups added during the cycles, therefore, have no detectable impact on the overall conversion of NO over carbon, but control the pathway to achieving stable conditions. Carbon catalysts prepared with acidic oxygen functionalities are promising as NO oxidation catalysts, as confirmed with NO2 and nitric acid treatments. It is proposed that carbon’s chemical properties impact NO oxidation kinetics while carbon’s physical properties impact the steady-state NO oxidation rate.

The slow strain rate test (SSRT) technique was used to investigate the stress corrosion cracking (SCC) susceptibility of sigmatized super duplex stainless steel (SDSS) grade UNS S32760, exposed to a simulated oilfield brine containing carbon dioxide/hydrogen sulfide (CO2/H2S) at 80°C. The sigma phase was precipitated by heat treatment (HT) at 850°C for various durations (0 to 12 min). Results show that low levels (less than 2%) of sigma have no profound impact on the mechanical and corrosion properties of SDSS. However, at higher levels (greater than 2%) of sigma phase, there is severe loss in ductility and increased corrosion rate. Fractographic observations using scanning electron microscopy (SEM) show that the fracture mode shifts from ductile to transgranular cracking with increasing levels of sigma phase. Electron-backscattered diffraction (EBSD) results show that crack nucleation occurs in the sigma grains. The cracking mechanism involves brittle fracture of sigma phase and slip-assisted anodic diss...

NO oxidation catalyzed by porous materials is difficult to implement under industrial conditions because moisture in combustion exhaust streams blocks oxidation sites, decreasing NO conversion. In this work, hydrophobic cross-linked polymers are tested as NO oxidation catalysts to overcome these negative impacts associated with moisture. Although activated carbons (ACs) outperform hyper-cross-linked polymers by88% and low-cross-linked polymers by463% under dry conditions, their NO conversion drops to 0% when 50% relative humidity is added. Performance of hyper-cross-linked and low-cross-linked polymers, however, decreases by only 19-35% and6%, respectively, for NO conversion in the presence of moisture. NO conversion differences between materials are attributed to differences in the catalysts' initial hydrophilicity and their proclivity to react with generated NO2, which also increases hydrophilicity. While the initial hydrophobicity of the polymers contributes to their consistent performance, it is their intrinsic ability to resist NO2 reduction reactions, compared to AC, that makes them the more viable catalyst for industrial application. Results suggest that the polymer hyper-cross-linking process improves steady-state NO conversion but increases NO2 surface reactivity and hydrophilicity.

A recently developed carbon material, electrospun Activated Carbon nanoFiber (ACnF), exhibits strong potential for use as an adsorbent for toxic industrial chemicals (TICs). As-prepared ACnF contains as much as 9.6 wt% nitrogen, creating a basic surface that enhances acid-gas adsorption. ACnF shows 4–20 times greater HCN adsorption capacities and 2–5 times greater SO2 adsorption capacities in dry nitrogen, compared to commercially available activated carbon fiber cloth (ACFC) and Calgon BPL™ granular activated carbon, which are considered here as reference adsorbents. ACnF has 50 % of the micropore volume (0.30 cm3/g) of these reference adsorbents, which limits its adsorption capacity at high concentrations for volatile organic compounds (>500 ppmv). However, at low concentrations (

Carbon-based adsorbents contain high internal surface area, desirable pore structure, and controlled surface functionalities, making them effective for gas purification, separation, and storage. This research describes a simple technique for preparing porous carbons from solid organic salt precursors and examines the physical and chemical properties of these materials. A two-step (i.e., pyrolysis and washing), fixed-bed system is used to synthesize high surface area carbon from solid organic salt precursors. The organic salts are pyrolyzed to remove reactive leaving groups (i.e., H2O, CO, CO2, and/or HCl). The remaining carbon atoms network around an in situ, solid salt template to develop internal porosity. Post-pyrolysis washing dissolves the salt template to isolate the remaining porous carbon products. Increased microporosity and surface area occur with this technique when compared to carbons prepared by a similar spray pyrolysis approach. Carbons prepared with the two-step method are >70% microporous and up to 740 m2/g. Surface oxygen content of these carbons increases from 5% to 25% with decreasing pyrolysis temperature. This technique provides control over surface area and oxygen content of the carbon products, an important step towards tailoring the carbon’s adsorption capacity for specific applications.

Nitrogen-containing porous carbon was synthesized from an ocean pollutant, Enteromorpha prolifera, via hydrothermal carbonization and potassium hydroxide activation. Carbons contained as much as 2.6% nitrogen in their as-prepared state. Physical and chemical properties were characterized by XRD, N(2) sorption, FTIR, SEM, TEM, and elemental analysis. The carbon exhibited a hierarchical structure with interconnected microporosity, mesoporosity and macroporosity. Inorganic minerals in the carbon matrix contributed to the development of mesoporosity and macroporosity, functioning as an in situ hard template. The carbon manifested high CO(2) capacity and facile regeneration at room temperature. The CO(2) sorption performance was investigated in the range of 0-75°C. The dynamic uptake of CO(2) is 61.4 mg/g and 105 mg/g at 25°C and 0°C, respectively, using 15% CO(2) (v/v) in N(2). Meanwhile, regeneration under Ar at 25°C recovered 89% of the carbon's initial uptake after eight cycles. A piecewise model was employed to analyze the CO(2) adsorption kinetics; the Avrami model fit well with a correlation coefficient (R(2)) of 0.98 and 0.99 at 0°C and 25°C, respectively.

Porous carbon microspheres impregnated with iron-based nanoparticles are prepared in a single step, continuous process using ultrasonic spray pyrolysis (USP). Precursor solutions containing a carbon source, an inorganic salt, and an iron salt are ultrasonically aerosolized and pyrolyzed. Solutions containing nitrate or chloride salts are examined. During pyrolysis, sucrose is dehydrated to carbon, and the metal salt is converted to crystalline or non-crystalline iron species, depending on processing conditions. The product’s porosity is generated from: (1) aromatization of carbon around an in situ template, (2) in situ gasification of isolated carbon, or (3) in situ chemical activation of the carbon precursor. Porous carbon spheres (0.5–3 μm diameter) containing well-dispersed iron oxide nanoparticles (4–90 nm diameter), referred to here as Fe–C, are prepared. Iron loadings between 1 and 35 wt.% are achieved while maintaining well-dispersed Fe nanoparticles with as-produced surface areas up to 800 m 2 /g. Post-pyrolysis heat and hydrogen treatments increase the surface area of the materials while reducing iron species. USP Fe–C materials may have useful catalytic applications due to their potential for high-loading of well-dispersed metal nanoparticles. Despite negligible surface Fe content, chromium reduction tests indicate that internal Fe sites are catalytically active.

Little is known of hospital practice in brain death determination, specialty involvement, and followed procedures, including the apnea test.We reviewed 228 patients pronounced brain dead at Mayo Clinic from 1996 to 2007. We performed a detailed review of clinical determination of brain death, intensive care support, apnea test procedure, and complications.There were 228 patients who were pronounced brain dead, mostly after traumatic brain injury, cerebral hematoma, or aneurysmal subarachnoid hemorrhage. Brain death was declared within 24 hours of ictus in 30% of the patients and within 3 days in 62%. All patients were using one or more vasopressors, and 61% of the patients received vasopressin for diabetes insipidus. An apnea test could not be performed in 7% of the patients because of hemodynamic instability or poor oxygenation at baseline. In 3% of the patients, the apnea test procedure was aborted because of hypoxemia or hypotension. No major complications (cardiac arrest or pneumothorax) occurred during the apnea test. Polytrauma resulting in brain death was significantly more common in patients with aborted or not attempted apnea tests than in patients with completed apnea tests (p = 0.0004). During the study epoch, we found a shift toward determination of the tests by neurointensivists, pediatric neurologists, and neurosurgeons.Brain death declaration is frequent within the first 3 days of admission. It is usually performed in hemodynamically unstable patients requiring vasopressors and vasopressin. If preconditions are met, apnea testing using an oxygen-diffusion technique is safe. However, in 1 of 10 patients, an apnea test could not be completed and confirmatory tests were needed.

Incomplete regeneration of activated carbon loaded with organic compounds results in heel build-up that reduces the useful life of the adsorbent. In this study, microwave heating was tested as a regeneration method for beaded activated carbon (BAC) loaded with n-dodecane, a high molecular weight volatile organic compound. Energy consumption and desorption efficiency for microwave-heating regeneration were compared with conductive-heating regeneration. The minimum energy needed to completely regenerate the adsorbent (100% desorption efficiency) using microwave regeneration was 6% of that needed with conductive heating regeneration, owing to more rapid heating rates and lower heat loss. Analyses of adsorbent pore size distribution and surface chemistry confirmed that neither heating method altered the physical/chemical properties of the BAC. Additionally, gas chromatography (with flame ionization detector) confirmed that neither regeneration method detectably altered the adsorbate composition during desorption. By demonstrating improvements in energy consumption and desorption efficiency and showing stable adsorbate and adsorbent properties, this paper suggests that microwave heating is an attractive method for activated carbon regeneration particularly when high-affinity VOC adsorbates are present.

Unruptured intracranial aneurysms (UIAs) are a major public health issue. These lesions have become increasingly recognized in recent years with the advent of advanced cerebral imaging techniques. Epidemiological evidence from multiple sources suggests that most intracranial aneurysms do not rupture. Therefore, it is desirable to identify which UIAs are at greatest risk of rupture when considering which to repair. It is important to compare size-, site-, and group-specific natural history rates with size-, site-, and age-specific morbidity and mortality associated with UIA repair because increased natural history risk often is associated with increased risk of aneurysm repair. Patient age is crucial in decision making because of its major effect on operative morbidity and mortality; however, it does not substantially affect natural history. The effect of age is most notable in patients about 50 years of age and older for open surgery and about 70 years of age and older for endovascular procedures. In general, rupture risk is lowest for patients in asymptomatic group 1 (no history of subarachnoid hemorrhage) with UIAs less than 7 mm in diameter in the anterior circulation. Surgical morbidity and mortality are most favorable for asymptomatic patients younger than 50 years who have UIAs less than 24 mm in diameter in the anterior circulation and no history of ischemic cerebrovascular disease. Endovascular morbidity and mortality may be less age dependent, and this could favor endovascular procedures, particularly in patients aged 50 to 70 years. An important issue is determining immediate vs long-term risk regarding treatment effectiveness and durability. This issue emphasizes the importance of long-term follow-up in patients after surgical and endovascular procedures.

Edaravone, a novel free radical scavenger, demonstrates neuroprotective effects by inhibiting vascular endothelial cell injury and ameliorating neuronal damage in ischemic brain models. The present study was undertaken to verify its therapeutic efficacy following acute ischemic stroke. We performed a multicenter, randomized, placebo-controlled, double-blind study on acute ischemic stroke patients commencing within 72 h of onset. Edaravone was infused at a dose of 30 mg, twice a day, for 14 days. At discharge within 3 months or at 3 months after onset, the functional outcome was evaluated using the modified Rankin Scale. Two hundred and fifty-two patients were initially enrolled. Of these, 125 were allocated to the edaravone group and 125 to the placebo group for analysis. Two patients were excluded because of subarachnoid hemorrhage and disseminated intravascular coagulation. A significant improvement in functional outcome was observed in the edaravone group as evaluated by the modified Rankin Scale (p = 0.0382). Edaravone represents a neuroprotective agent which is potentially useful for treating acute ischemic stroke, since it can exert significant effects on functional outcome as compared with placebo.

Background and purpose:The authors studied the clinical and neuroimaging features of cerebellar hematomas to predict poor outcome using comprehensive statistical models.Methods:We retrospectively reviewed clinical and neuroimaging features in 94 patients with spontaneous cerebellar hematomas to identify predictive features for a poor neurologic outcome, defined as death or dismissal to long-term care facility. Data were analyzed using chi square and Fisher's exact test with calculation of odd's ratios together with 95% confidence intervals.Results:Clinical and neuroradiologic predictors for a poor outcome at p < 0.05 were admission systolic blood pressure > 200 mm Hg, hematoma size >3cm, visible brain stem distortion, and acute hydrocephalus. Presenting findings predicting subsequent death at p < 0.05 were abnormal corneal and oculocephalic responses, Glasgow coma sum score less than 8, motor response less than localization to pain, acute hydrocephalus and intraventricular hemorrhage.Conclusion:A tree-based analysis model using binary recursive partitioning showed that cornea reflex, hydrocephalus, doll's eyes, age, and size were the most important discriminating factors. Absent corneal reflexes on admission highly predicts poor outcome (86 percent, confidence limits 67-96 percent). When a cornea reflex is present, acute hydrocephalus predicts poor outcome but only when doll's eyes are additionally absent.