CO Peak Research Articles

Deep-convective influence on the upper troposphere–lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign results

Abstract. The StratoClim stratospheric aircraft campaign took place in summer 2017 in Nepal (27 July–10 August) and provided for the first time a wide dataset of observations of air composition inside the Asian monsoon anticyclone (AMA). In the framework of this project, with the purpose of modelling the injection of pollutants and natural compounds into the stratosphere, we performed a series of diffusive back trajectory runs along the flights' tracks. The availability of in situ measurements of trace gases has been exploited to evaluate the capability of the trajectory system to reproduce the transport in the upper troposphere–lower stratosphere (UTLS) region. The diagnostics of the convective sources and mixing in the air parcel samples have been derived by integrating the trajectory output with high-resolution observations of cloud tops from the Meteosat Second Generation (MSG1) and Himawari geostationary satellites. Back trajectories have been calculated using meteorological fields from European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-Interim and ERA5) at 3 and 1 h resolution, using both kinematic and diabatic vertical motion. The comparison among the different trajectory runs shows, in general, a higher consistency with observed data as well as a better agreement between the diabatic and kinematic version when using ERA5-based runs with respect to ERA-Interim. Overall, a better capacity in reproducing the pollution features is finally found in the diabatic version of the ERA5 runs. We therefore adopt this setting to analyse the convective influence in the UTLS starting from the StratoClim observations. A large variety of transport conditions have been individuated during the eight flights of the campaign. The larger influence by convective injections is found from the continental sources of China and India. Only a small contribution appears to be originated from maritime regions, in particular the South Pacific and the Bay of Bengal, which, unexpectedly, was not particularly active during the period of the campaign. In addition, a mass of clean air injected from a typhoon has also been detected at around 18 km. Thin filamentary structures of polluted air, characterized by peaks in CO, are observed, mostly associated with young convective air (age less than a few days) and with a predominant South China origin. The analysis revealed a case of direct injection of highly polluted air close to the level of the tropopause (anomalies of around 80 ppbv injected at 16 km) that then kept rising inside the anticyclonic circulation. Due to the location of the campaign, air from continental India, in contrast, has been only observed to be linked to air masses that recirculated within the anticyclone for 10 to 20 d, resulting in a lower concentration of the trace gas. The analysis of a flight overpassing an intense convective system close to the southern Nepalese border revealed the injection of very young air (few hours of age) directly in the tropopause region (∼18 km), visible in the trace gases as an enhancement in CO and a depletion in the O3 one. From the whole campaign, a vertical stratification in the age of air is observed: up to 15 km, the age is less than 3 d, and these fresh air masses constitute almost the totality of the air composition. A transition layer is then individuated between 15 and 17 km, where the convective contribution is still dominant, and the ages vary between 1 and 2 weeks. Above this level, the mean age of the air sampled by the aircraft is estimated to be 20 d. There, the convective contribution rapidly decreases with height and finally becomes negligible around 20 km.

Comprehensive study on co-combustion behavior of pelletized coal-biomass mixtures in a concentrating photothermal reactor

Co-combustion of biomass offers a great potential to reduce CO2 emissions but rarely mentioned co-combustion behavior of pelletized coal-biomass mixtures and inconclusive results based on single determinants formed obstacle for industrial application. In this study, ignition and flame characteristics, reaction and kinetic parameters and pollutant generation path were comprehensively investigated. Intrinsic combustion experiments were carried with the gas phase maintaining at room temperature in a concentrating photothermal reactor at heating rate over 200 °C/s. Same “homogeneous” ignition was evidenced while advanced devolatilization but more intense slagging behaviors were identified with the increase of biomass proportion. With the biomass proportion increased from 0% to 40%, the activation energies during devolatilization to ignition decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol, indicating the existence of synergistic effect. CO exhibited relative high generation rates and the generation rate increased with the biomass content. Three fitted CO peaks were identified during co-combustion, which were contributed by devolatilization of coal and biomass, and combustion of char, respectively. First increased and then decreased NO emission with the increase of biomass proportion was evidenced for the higher N content in biomass but enhanced reduction by char and NH radicals with higher biomass proportion.

Biosorption of Lead and Chromium Ions by Using Penicillium digitatum (Pers.) Sacc. from Industrial Water

Some microorganisms, including fungi, are characterized by their removal efficiency and reducing the concentrations of heavy metals such as Pb and Cr from industrial water. The present study aims to estimate the efficiency of Penicillium digitatum (Pers.) Sacc. as a low-cost biosorbent in reducing Pb and Cr from industrial water with optimum biosorption conditions (acidity of 1.5 , 4, and 5; temperature of 30 °C). The Fourier transform infrared spectroscopy (FTIR) analysis was also used for determining the roles of the functional groups in this biosorbent. The results indicated that the highest P. digitatum efficiency values for reducing the levels of Pb and Cr were 84% and 70% , respectively, at pH of 5 after 24 h. However, this efficiency was decreased from 81% to76% at pH values of 4 and 1.5, respectively, for Pb. The removal efficiency for Cr was 56% at pH of 4 after 1h. at 30 °C. Also, the FTIR spectra illustrated -CH, -C-N, N-H, and =CO peaks of functional groups that may change as a result of their involvement in the adsorption process of lead and chromium.

Designation and characterization of cold-set whey protein-gellan gum hydrogel for iron entrapment

This study is aimed at designing of a composite cold-set hydrogel using whey protein isolate (WPI) and gellan gum as iron carrier. The effect of total polymer concentration (TPC) (0.5 and 1.5%), WPI/gellan ratio (1:1, 1:2, and 1:3), and iron concentration (10, 40, and 70 mM) on physicochemical and rheological characteristics of hydrogel were analyzed. By increasing TPC, the release mechanism became complex regarding less erosion of structure in simulated gastrointestinal medium. Moreover, the CO peak area of FTIR spectra was enhanced. As WPI/gellan ratio decreased, the faster release occurred due to a more porous structure. The cumulative release of iron in acidic and neutral pH increased up to 71.74 and 9.14%; however, iron was released up to 88.55 and 28.72% in simulated gastric and intestinal medium, respectively. The iron release followed a chemically-controlled mechanism in all samples. The area and number of gel pores and water-holding capacity decreased as Fe concentration was enhanced, but denaturation temperature increased. These results suggest that the strong texture with a solid elastic behavior along with a high cumulative release of iron made our hydrogel suitable for iron delivery to reduce iron deficiency-related disorders.

Spectral manifestations of coal metamorphism: Insights from coal microstructural framework

The present study investigates the microstructural framework of coals from the Raniganj and the Jharia Basins as well as from the Himalayan fold-thrust belts of Sikkim, India, by vitrinite reflectance, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The mean random vitrinite reflectance data may imply that the coal samples from the Raniganj and the Jharia Basins range from the bituminous D to B, and would have experienced the burial heating corresponding to ~92 °C to 143 °C unlike the anthracite A samples that might have undergone the hydrothermal metamorphism at ~333 °C to 367 °C. The Raman spectra exhibit preferential removal of sp3 hybridized moieties from the anthracite samples at anchizonal metamorphic stage due to thermo-stress degradation effect induced by the Himalayan orogeny. Further, this study records the reduction of net dipole moment change due to the expulsion of functional groups from the aromatic rings making them infrared inactive. Additionally, the C1s spectra reveal the thinning of CC peaks and the lowering of the CO peak intensity with an increase in coal rank. This study, hence, documents the microstructural transformations in coal that can be used for structural maneuvering to control the liquefaction, gasification, pyrolysis, combustion as well as synthetic graphitization behavior.

Construction of a unique anti-corrosion nanocomposite based on graphene oxide@Zn3PO4/epoxy; experimental characterization and detailed-theoretical quantum mechanics (QM) investigations

The highly crystalline zinc phosphate (ZnP) compounds were synthesized over the graphene oxide surface through one and two-steps in-situ methods (namely GO-ZnP I and II). FT-IR studies revealed that the CO peak weakened or completely removed in the GO-ZnP I, II samples. Raman spectroscopy results evidenced the higher ID/IG ratio for the unmodified GO than GO-ZnP I and II, confirming the zinc phosphate crystals growth on the GO surface. Results of XPS and Raman spectroscopy proved the GO-ZnP I and II crystals formation on the GO platelets. ICP analysis results depicted about 11.6 ppm and 10.7 ppm zinc ions presence in NaCl solution, evidencing the partial solubility of the GO-ZnP I and for GO-ZnP II particles. A smart self-healing nanocomposite coating with promising anti-corrosion effect and dual active/barrier functions was designed using GO-ZnP I and II nanosheets. EIS studies on mild steel samples exposed to the saline solutions containing GO-ZnP I and GO-ZnP II particles extract demonstrated inhibition efficiencies of about 76 and 69%, respectively. According to EIS analysis, the total resistance (Rt) values of 11480, 12048, 9105, and 7512 Ω·cm2 were recorded for the EP/GO-ZPII, EP/GO-ZPI, neat epoxy, and EP/GO samples, respectively, after 48 h of exposure to saline solution confirming the superior anti-corrosion performance of the scratched EP in the presence of GO-ZP particles. The GO-ZPII loaded epoxy matrix showed low-frequency impedance values greater than 1010 Ω·cm2 even after 39 days of exposure, indicating the superior barrier effect of the particles in the coating formulation. The EIS evaluation and accelerated salt-fog spray corrosion test results showed the effectiveness of GO-ZnP II and I composites (at 0.15 wt% loading) in epoxy coating active inhibitive/barrier performance promotion. Additionally, the theoretical density functional theory (DFT) results declared the zinc phosphate adsorption on the GO surfaces.

Oxidation characteristics of heavy oil and its SARA fractions during combustion using TG-FTIR

The oxidation reactions between air and crude oils play a key role in in-situ combustion (ISC). This study is intended to explore the oxidation characteristics of one heavy oil and its SARA fractions by thermogravimetry associated with Fourier transform infrared spectroscopy (TG-FTIR). The results indicated the release behavior of typical evolved gases (hydrocarbons, CO2, CO, and H2O) during oxidation for the oil and its SARA fractions existed huge difference because of different structures and compositions. The heavy oil encountered appreciable weight loss at the low temperature oxidation (LTO) region where hydrocarbons, CO2, H2O, etc., were released. Quite a few coke could be formed from the LTO residue of heavy oil during fuel deposition (FD), thus resulting in a pronounced high temperature oxidation (HTO) stage characterized with apparent mass loss and one notably sharp peak of CO2. Saturates experienced a great amount of mass loss and release of hydrocarbons in the LTO regime. Aromatics showed obvious LTO and FD intervals in terms of mass loss and evolved gases, but its most of intermediate products during FD were evaporated with the temperature leading to the occurrence of weak HTO reactions. Resins was subjected to a small amount of mass loss and release of hydrocarbons and H2O in the LTO interval, and some of its intermediate products during FD formed coke through condensation reactions, which consequently led to a pronounced HTO stage. For asphaltenes, almost no hydrocarbons, CO2 and CO were released in the LTO region, and most of intermediate products at the initial FD stage condensed with each other to form coke. During HTO of asphaltenes, an extremely distinctive peak of CO2 and a small shoulder peak of CO and H2O were observed, verifying the occurrence of fierce combustion reactions.

Efficient utilization of waste plastics as raw material for metallic iron and syngas production by combining heat treatment pulverization and direct reduction

For the clean and efficient utilizaiton of waste plastics, an integrated flowsheet, including low temperature heat treatment pulverization and composite pellet reduction, has been proposed and the fundamental research has been conducted. The PE film could be easily pulverized by heat treatment at 250°C for 20min after mixed with coal powder (mass ratio of PE 20 % of coal). The pulverized heated mixture had better reactivity than original coal and could be used as the reducing agent of composite pellet. The reducibility of heated mixture pellet was better than coal pellet with the C/O of 1.0. The appropriate reduction temperature should be around 1100°C and the metallization degree was bigger than 90 % when reduced for 30min. The off gas of heated mixture pellet contained more H2 and CO. The concentration value of H2 peak of heated mixture pellet was 5 times of that of coal pellet. However, the concentration value of largest CO peak of heated mixture pellet was about 48.7 % higher than that of coal pellet. The experimental results show the possibility that the novel technology can efficiently utilize iron ore and waste plastics to produce metallic iron and syngas.

Resolving the Interstellar Medium in Ultraluminous Infrared QSO Hosts with ALMA

Abstract We present ALMA observations of the CO(1−0) line and 3 mm continuum emission in eight ultraluminous infrared (IR) quasi-stellar objects (QSOs) at z = 0.06–0.19. All eight IR QSO hosts are clearly resolved in their CO molecular gas emission with a median source size of 3.2 kpc, and seven out of eight sources are detected in 3 mm continuum, which is found to be more centrally concentrated with respect to molecular gas with sizes of 0.4−1.0 kpc. Our observations reveal a diversity of CO morphology and kinematics for the IR QSO systems, which can be roughly classified into three categories: rotating gas disk with ordered velocity gradient, compact CO peak with disturbed velocity, and multiple CO distinct sources undergoing a merger between a luminous QSO and a companion galaxy separated by a few kpc. The molecular gas in three of the IR QSO hosts is found to be rotation-dominated with a ratio of the maximum rotation velocity to the local velocity dispersion of V rot/σ = 4–6. Basic estimates of the dynamical masses within the CO-emitting regions give masses between 7.4 × 109 and 6.9 × 1010 M ⊙. We find an increasing trend between black hole mass accretion rate and star formation rate (SFR) over 3 orders of magnitude in far-IR luminosity/SFR, in line with the correlation between QSO bolometric luminosity and star formation activity, indicative of a likely direct connection between active galactic nuclei and star formation activity over galaxy evolution timescales.

Peaks of transportation CO2 emissions of 119 countries for sustainable development: Results from carbon Kuznets curve

AbstractTransportation has significantly boomed energy consumption and carbon dioxide (CO2) emissions. Understanding and forecasting the dynamic statuses of transportation CO2 emissions is a necessary step before making strategies to decrease CO2 emissions. Carbon Kuznets curve (CKC) hypothesis has been frequently validated properly to present the changing statuses of CO2 emissions in the literature. This study tests the CKC hypothesis using the data recording the CO2 emissions of transportation sectors of 119 countries over the period of 1995–2014, then turning points (TPs) are calculated for the countries where CKC hypothesis is turned out supported. Based on the CKC models, this study identifies different types of TPs, i.e. TP of carbon intensity (TPCI), TP of per capita CO2 emissions (TPPC), and TP of total CO2 emissions (TPTC) of the countries whose data support the CKC hypothesis. According to the earliness of the turning years (TYs) (TYCI, TYPC and TYTC) – the years when CO2 emissions peak – of individual countries, this study identified a step‐wise decoupling strategy for different countries, i.e. (1) first to reach the TPCI, (2) then to reach the TPPC, and (3) finally to reach the TPTC. As a result, the CKC hypothesis was supported by the data of 58 countries, among which, there are still seven countries having not reached any of the three TPs, 23 countries have reached the first‐step TP (TPCI), 9 countries have reached the second‐step TP (TPPC), and 19 countries have reached the third‐step TP (TPTC).

Anchored quaternary ammonium salts adsorbed on polyurethane film surfaces

A flexible, thermoset and transparent polyurethane (PUR) film with high glass transition temperature, has been deployed as a substrate for anchoring anti-bacterial molecular layers. These layers are formed by adsorbing, from an aqueous solution, a silyl anchoring quaternary ammonium salt (AQAS) with a long alkyl chain (C18) onto the PUR film surface, followed by thermal curing at 160 °C. The presence of AQAS adsorbed on the PUR film surface is confirmed by the appearance of a distinctive N1 s level XPS peak at 402 eV, attributed to quaternary nitrogen (N+). The carbonyl groups on the PUR surface appear to be the main surface binding sites for the adsorbed AQAS molecules. This interpretation is validated by the relative decrease in the intensities observed for the ν (CO) at 1700 cm−1 in the infrared spectra, and decreases in the intensity of the C1 s binding energy peak for CO at 289 eV in the XPS spectra of the PUR following AQAS adsorption. Leaching studies suggest a chemisorbed first layer and several leachable higher layers of oligomeric forms of AQAS. A PUR surface incorporating a blended polydimethylsiloxane additive exhibits similar adsorptive capacity to pristine PUR. However exposing the PUR films to oxygen plasma treatment prior to AQAS adsorption leads to a higher coverage of the adsorbate on the PUR surface. The anchoring quaternary ammonium salt (AQAS) in this current work has established potencies against a wide range of critical organisms. Antibacterial assays adapted from the JIS 2801 wet fomite method confirm the potency (3-log reduction) of these PUR-AQAS films against Staphylococcus aureus and Escherichia coli.

Investigating the Kinetic Competency of CrHydA1 [FeFe] Hydrogenase Intermediate States via Time-Resolved Infrared Spectroscopy.

Hydrogenases are metalloenzymes that catalyze the reversible oxidation of H2. The [FeFe] hydrogenases are generally biased toward proton reduction and have high activities. Several different catalytic mechanisms have been proposed for the [FeFe] enzymes based on the identification of intermediate states in equilibrium and steady state experiments. Here, we examine the kinetic competency of these intermediate states in the [FeFe] hydrogenase from Chlamydomonas reinhardtii (CrHydA1), using a laser-induced potential jump and time-resolved IR (TRIR) spectroscopy. A CdSe/CdS dot-in-rod (DIR) nanocrystalline semiconductor is employed as the photosensitizer and a redox mediator efficiently transfers electrons to the enzyme. A pulsed laser induces a potential jump, and TRIR spectroscopy is used to follow the population flux through each intermediate state. The results clearly establish the kinetic competency of all intermediate populations examined: Hox, Hred, HredH+, HsredH+, and Hhyd. Additionally, a new short-lived intermediate species with a CO peak at 1896 cm-1 was identified. These results establish a kinetics framework for understanding the catalytic mechanism of [FeFe] hydrogenases.

Size-controlled model Ni catalysts on Ga2O3 for CO2 hydrogenation to methanol

The effect of particle size for Ni nanoparticles supported on β-Ga2O3 was investigated for CO2 hydrogenation to methanol at 0.5 MPa. Model Ni nanoparticles ranging from 3.3 to 10.2 nm were synthesized using the hot injection method by controlling the reaction temperature and time. The smallest Ni nanoparticles (3.3 nm) showed the highest catalytic activity across the entire temperature range and the largest Ni nanoparticles (10.2 nm) showed the highest methanol selectivity. The apparent activation energies for methanol with Ni nanoparticles increased from 6.0 to 18.4 kcal mol−1 as the nanoparticle size increased. Furthermore, it was found that the smallest Ni nanoparticles favor the reverse water gas shift reaction. In situ DRIFT analysis revealed that the gallium oxide itself could produce an intermediate species and the addition of Ni on the oxide support increases the hydrogenation rate. The Ni supported catalysts showed a CO peak, but the smallest Ni nanoparticles showed a larger CO peak than that for the largest Ni nanoparticles, which clearly supports that the smaller nanoparticles favor the reverse water gas shift reaction.

ALMA Observations of Molecular Gas in the Host Galaxy of AT2018cow

Abstract We investigate the molecular gas in and star formation properties of the host galaxy (CGCG 137–068) of a mysterious transient, AT2018cow, at kpc and larger scales, using archival band-3 data from the Atacama Large Millimeter/submillimeter Array (ALMA). AT2018cow is the nearest fast-evolving luminous transient (FELT); this is the first study unveiling molecular-gas properties of FELT hosts. The achieved rms and beam size are 0.21 mJy beam−1 at a velocity resolution of 40 km s−1 and 3.″66 × 2.″71 (1.1 kpc × 0.8 kpc), respectively. CO(J = 1–0) emission is successfully detected. The total molecular gas mass inferred from the CO data is (1.85 ± 0.04) × 108 M ⊙ with the Milky Way CO-to-H2 conversion factor. The H2 column density at the AT2018cow site is estimated to be 8.6 × 1020 cm−2. The ALMA data reveal that (1) CGCG 137–068 is a normal star-forming (SF) dwarf galaxy in terms of its molecular gas and star formation properties, and (2) that AT2018cow is located between a CO peak and a blue star cluster. These properties suggest ongoing star formation and favor the explosion of a massive star as the progenitor of AT2018cow. We also find that CGCG 137–068 has a solar or super-solar metallicity. If the metallicity of the other FELT hosts is not higher than average, then some properties of SF dwarf galaxies other than metallicity may be related to FELTs.

Synthesis of nanopowders in a PECVD reactor from organosilicon precursor

In previous work, nanopowders have been obtained during the deposition of thin layers from Hexamethyldisiloxane (HMDSO) using low frequency plasma. The aim of this work is the study of the growth process of these nanopowders in plasma discharge and in deposited films. The plasma discharge was generated from HMDSO precursor in low frequency reactor; optical emission spectroscopy (OES) and scanning electron microscopy (SEM) have been used to investigate the effect of the deposition parameters on the nanopowders growth in the plasma discharge and in the deposited thin layers respectively. For high deposition pressure, OES reveals the presence of SiH (situated at 414 nm), OH (situated at 309 nm), CHO (situated at: 324.3, 351.5 nm) species and some additional emission peaks of CO (situated at: 540.9, 566.6, 578, 646,6 nm). The intensities evolution of these species have been investigated during the discharge plasma and the presence of some of them may be the result from the reaction of the nanoparticles of the deposited powders with the plasma species. Nanoparticles agglomerations have been revealed by SEM observations and their aspect correlated with optical emission spectroscopy measurements.

Photochemical degradation of acrolein using VUV excimer lamp in air at atmospheric pressure

The photochemical degradation of acrolein (C2H3CHO) was investigated in air at atmospheric pressure using a 172-nm Xe2 excimer lamp. When C2H3CHO was decomposed using the side-on type of lamp, HCOOH, CO, CO2, and O3 peaks were observed in FTIR absorption spectra. The dependence of product concentrations on the irradiation time indicated that HCOOH and CO intermediates are finally converted to CO2 via consecutive reactions. The degradation rate coefficient of C2H3CHO in the batch system increased from 8.4 to 19.3 min−1, as the O2 concentration was decreased from 20 to 1%. It increased also from 8.4 to 40.1 min−1 at 20% O2, as the chamber depth was decreased from 3.0 to 0.5 cm. The best energy efficiency of the C2H3CHO degradation was 3.4 g kW−1 h−1 at 1–20% O2 in a flow system. Besides direct VUV photodissociation of C2H3CHO, reactions of O(3P,1D) and O3, produced from photolysis of O2, can contribute to C2H3CHO degradation in the initial stage. Among them, the contribution of O(1D) and O3 was found to be insignificant on the basis of the total pressure dependence of removal amount of C2H3CHO and results obtained from the O3 + C2H3CHO reaction. It was concluded that at first C2H3CHO is decomposed by direct VUV photodissociation of C2H3CHO and the O(3P) + C2H3CHO reaction. It was further decomposed by secondary reactions of O(3P), OH, and O3 with such intermediates as HCOOH and CO and finally oxidized to CO2.

Effects of isomerization and concentration on the surface plasmon induced intermolecular hydrogen bonds enhancement of fluorobromobenzaldehydes

The surface plasmon facilitated intermolecular hydrogen bonds enhancement of fluorobromobenzaldehyde (F-BB) isomers on Ag nanoparticles have been investigated by means of surface-enhanced Raman scattering (SERS). Comparing the SERS spectra and normal Raman scattering (NRS) spectra, the intensity of the O⋯H bending vibration peak was found to be clearly enhanced, and a new CO peak appeared in the SERS spectrum. The CO stretching vibration Raman spectrum reduced. We surmise that intermolecular hydrogen bonds are strengthened, due to the surface plasmon effect generated hot electrons act on the aldehyde group. Our work may promote further investigations on intra/intermolecular hydrogen-bonded chemical systems.

Sulfenamides in synergistic combination with halogen free flame retardants in polypropylene

Sulfenamide based radical generators that contain a nitrogen-sulfur (N-S) core, can alone provide flame retardancy in polypropylene (PP), polyethylene and polystyrene, as we have earlier demonstrated. Herein, sulfenamides potential as synergists with conventional halogen free flame retardants has been explored. Thus, five different sulfenamides were individually combined with selected eco-friendly, phosphorus based flame retardants or aluminium trihydroxide (ATH), and their effect on polypropylene flammability was assessed by limiting oxygen index (LOI), vertical flammability (UL 94 V) and cone calorimeter tests. Thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) studies were carried out to detect changes in thermal behaviour when such two component FR systems were mixed together at different ratios. TGA-FTIR (thermogravimetric analysis-Fourier transform infrared spectroscopy) was used to investigate the differences in decomposition products of non-flame retarded versus flame retarded PP. Strong synergistic effects were observed, and the UL 94 V-0 rating was reached for PP with a total FR loading of 10 wt% using 8 wt% of phosphonate ester AFLAMMIT®PCO 900 together with 2 wt% of sulfenamide flame retardant. In a ternary mixture of an additional phosphazene additive (SPB-100), the needed total concentration for V-0 rating was further reduced to 9 wt%. In addition, the combination of 4 wt% of aluminum hypophosphite (AHP) with 0.5 wt% of sulfenamide offered a unique halogen free solution for achieving UL 94 V-2 rating in PP. Cone calorimeter studies of an ammonium polyphosphate-pentaerythritol based intumescent system in combination with 0.5 wt% of sulfenamide also showed encouraging results. The char stability was enhanced, the peak of heat release rate (HRR), CO and CO2 production and total smoke generation were all reduced compared to the reference sample without sulfenamide.

The Chemical and Physical Effect of Diluent H2O on NO and CO Emissions in Computational CH4 / Air Laminar Diffusion Flames

The chemical and physical effects of H2O addition on the NO and CO emissions of CH4 / air diffusion laminar flames are numerically investigated at atmospheric pressure with the reduced mechanism. The reduced mechanism removes the mad components from GRI - mech 3.0 by the Directed Relation Graph ( DRG ) method and the Sensitivity Analysis ( SA ) method, then adds the virtual molecules FH2O, which have the same physical properties as an H2O molecule but no chemical properties. To distinguish the chemical and physical effects of H2O addition on NO and CO formation in flames, this study adds the same amount of H2O and FH2O additions to the fuel side and oxidant side, respectively. The simulation results are obtained for an equivalence ratio of 1 and addition ratios of 0, 10 %, 20 %, and 30 % ( θ ) of the fuel mixture volume. As a result, the temperature and the NO and CO emissions decrease with H2O addition increasing. When θ is 30 % in the fuel side, the NO and CO peak proportion along axis decreases 24 % and 16%, respectively. When the same amount of H2O and FH2O are added, the difference between the components identifies the chemical and physical effects of addition significantly, and the NO and CO pollutant reduction from methane burning with FH2O diluent is 0.5 ~ 0.8 of that with H2O diluent, because H2O addition affects the reaction paths, the high heat capacity and the dilution effect. H2O addition promotes NO consumption reactions by HCCO + NO = HCNO + CO and NO + CH2 = HNCO + H. And H2O addition changes the main route of CO production. When no diluent is added, CO is created by CH4 → CH3 → CH2O → HCO → CO and CH4 → CH3 → CH2(S) → CH2 → CH → CH2O → HCO → CO. However, the reaction rate of second route is decreased clearly by H2O diluent in fuel side.

Thermal characteristics and product formation mechanism during pyrolysis of penicillin fermentation residue

This work studied thermal characteristics and product formation mechanism during pyrolysis of penicillin fermentation residue (PR). Results showed that PR pyrolysis proceeded in four stages. The kinetic triplet of each stage was calculated using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and integral master-plot methods. The kinetic model for stage 1 was the three-dimensional diffusion model, the simple reaction order model for stage 2 and stage 4, and the nucleation-growth model for stage 3. FTIR analysis suggested that the intensities of absorption peaks of NH, CO, CH, CN, and CO in chars weakened gradually with increasing temperature, corresponding to the production of CH4, CO, NH3, and HCN. GC-MS results indicated that the high protein content in PR resulted in a high fraction of nitrogenated compounds (amides and amines, nitriles, and N-heterocyclic species) in bio-oil. The formation mechanism of these compounds was discussed. Besides, bio-oil also contained large quantities of oxygenated compounds and a few hydrocarbons.