Chlorinated polyvinyl chloride (CPVC) is a promising material candidate for sprinkler piping systems in seismic areas. CPVC samples were obtained from a pipe supplier and refabricated according to the dimensions in ASTM D638. Exposures were conducted in the Q-SUN xenon arc chamber with a window glass filter and a day light filter and also in QUV accelerated weathering tester. The Figure below is a graph from Q-Lab Products showing irradiance from different exposure methods.The left top corner in the figure lists the different exposure methods. The curves pertaining to a) Direct Sunlight, Noon Summer, b) Q-SUN Daylight-Q, c) Q-SUN Window-Q and d) QUV with UVB-313 are of interest in this study. Total energy exposed to the CPVC tensile specimens from QUV with UVB-313 lamps, Q-SUN xenon arc lamp used with a daylight filter and window glass filter in comparison with that of ASTM G177 sunlight over a period of 1 week, 4, 8, and 12 weeks was calculated. Energy levels used to expose the samples in the Q-SUN xenon arc chamber were 12 - 13 times greater than those used in the QUV accelerated weathering chamber. Literature shows that the shorter wavelengths in UVB light are more damaging. However, only minor tensile property changes were observed in the samples exposed to UVB light. A 70.4% reduction in the elongation at break was observed after 8 weeks of exposure in the Q-SUN xenon arc chamber with a daylight filter and a 67.7% reduction in the elongation at break was observed after 12 weeks with a window glass filter. Fourier Transform � Infrared Spectroscopy (FT-IR) analysis and preliminary Gel Permeation Chromatography (GPC) analysis revealed considerable changes. Field aged CPVC pipes were also analyzed.

Degradation studies on CPVC sprinkler piping material in QSUN xenon arc chamber and QUV weathering chamber

The free volume hole relaxation of polycarbonate (PC) was investigated by using positron annihilation lifetime (PAL) spectroscopy as a function of annealing time at different temperatures (116 �C, 125 �C) below the PC glass transition temperature (Tg ~ 161 �C). A slight decrease of the free volume of ortho-positronium (o-Ps) was observed with increasing aging time, while the o-Ps lifetime remains substantially unchanged, this may be attributed to a decrease in the amount of defects in the process of annealing. Differential scanning calorimetry (DSC) was used to characterize the thermal behavior as a result of aging time, and it is shown that enthalpy of relaxation (DH) has a clear increase with annealing time. The changes in nanostructure caused by annealing below Tg measured by PALS and DSC, seem in general not to be closely related. In conclusion, free volume relaxation appears to occur within minutes at room temperature after annealing even though the bulk thermal history is retained (DH).   is comparison of the fractional free volume (FFV) (top) and enthalpy of relaxation at different temperatures as a function of annealing time.

Experiments to correlate positron annihilation to thermal aging in polycarbonate

The electronic structures of two new quaternary polar intermetallic compounds of MxCa9-xIn8Ge8 (M = Eu, Sr; x = 3.13(2), 3.23(3)) have been investigated using tight-binding, linear muffin-tin orbital (TB-LMTO) method to understand the observed novel orthorhombic structure type and interatomic interactions among anionic components forming the 3-dimensional (3D) framework. Orbital contributions from two types of cations are also observed in the valence band region, which indicates a certain degree of interatomic interactions exist between cations and anions resulting in a pseudogap at the Fermi level (EF). A crystal orbital Hamilton population (COHP) analysis for five distinct anionic interactions within the 3D framework proves that the averaged In-Ge COHP curve for the InGe4 tetrahedron is nearly optimized at EF, whereas the Ge-Ge COHP curve for Ge2 dimer contains a small anti-bonding character. The unfavorable anti-bonding characters are compensated by large numbers of bonding interactions between cations and anions. Electron localization function (ELF) displays that attractors observed between In2-Ge2 and In2-Ge4 bond on the �12-membered ring� are relatively weaker than others observed in the rest of the pentagonal geometries due to the elongated bond distances. The attractors between In and Ge are mostly polarized toward Ge atoms due to the electronegativity difference. The obtained effective magnetic moment of Eu3.13(2)Ca5.87In8Ge8 is 7.12 �B/Eu atom, and ?P= -2.58K indicating a relatively low temperature antiferromagnetic (AFM) ordering of Eu atom.

Theoretical investigation and magnetism study for two novel polar intermetallic compounds: MxCa9-xIn8Ge8 (M = Eu, Sr; x = 3.13(2), 3.23(3))

Much attention has been focused on the surface science of titanium dioxide due to its numerous scientific and industrial to its applications in photocatalysis, electrochemistry, active coatings, gas sensors. Among these studies, many have focused on the interaction of water with rutile and anatase (110) surfaces, due to the fundamental role of water in many of the present and potential applications of TiO2. The vast majority of experimental and theoretical understanding of the adsorption behaviour of water on TiO2(110) concerns gas phase adsorption in ultra-high vacuum environments (<1x10-10 mbar). Here we present work that has characterised the atomic scale structure and composition of the liquid water interface using surface X-ray diffraction. For rutile (110), a 2x1 an ordered interface of terminal hydroxyls is formed, with water in the second layer. The clean anatase (101) in UHV is found close to that calculated, with a mixture of hydroxyls and water at the interface with an ultrathin layer of H2O.

Structure comparison of rutile TiO2(110) and anatase TiO2(101) and their interfaces with water

Occurrence of emerging contaminants in environmental waters is directly related to their removal in wastewater treatment plants (WWTPs) and the flow rate of the receiving waters. Conventional WWTPs were not designed to remove some organic compounds such as emerging pollutants. A wide array of micropollutants are usually found in WWTP efluents, so there is a need to develop and evaluate alternative treatments which could be efficient for their elimination.Advanced treatment technologies such membrane bioreactors (MBR) and photocatalytic processes could improve the removal of many emerging pollutants and thereby diminish their presence in surface waters. Mediterranean rivers are characterized by important fluctuations in the flow rates and heavy contamination pressures from extensive urban, industrial and agricultural activities. This translates in contamination levels most often higher than in other European basins. For instance, the Llobregat river basin (Catalonia, NE Spain) suffers from extreme and frequent flow fluctuations (1�100 m3 s-1) and receives the effluent discharges of more than 55 WWTPs, and at some points, especially in drought periods, the effluents may represent almost 100% of the total flow of the river. Thus, it is not strange to find considerably high levels of organic contaminants along the river and increasing concentrations when moving downstream due to the also increasing number of WWTPs and population pressure. Besides conventional contaminants such as pesticides, Hg, organochlorine compounds, polycyclic aromatic hydrocarbons (PAHs), alkylphenols and polybrominated diphenyl ethers (PBDEs), emerging contaminants such as pharmaceuticals and personal care products and illicit drugs represent an overgrowing portion of trace organic contaminants of concern in two studied Iberian rivers (Ebro and Llobregat). This presentation summarizes the findings of several studies and monitoring programs conducted with the aim of getting a better insight about the sources and fate of pesticides, pharmaceuticals, illicit drugs and personal care products in the aquatic environment in Spain. The occurrence of these contaminants is discussed in relationship to their removal in WWTPs, influence of hydrological conditions in the receiving river waters, sediments and dilution factors. The removal of some of them (e.g., acetaminophen, diclofenac, ibuprofen, carbamazepine and atenolol as well as the illicit drugs cocaine and methadone) with advanced water treatments and the study ofthe formed transformation products and their toxicity is also presented. In addition, the risk posed by these emerging contaminants in both surface and effluent wastewaters was assessed towards different aquatic organisms (algae, daphnids and fish) by determining hazard indexes.These indexes are further correlated with some biological descriptors characterizing both the structure and functioning of the receiving aquatic ecosystems such as biofilms or the macroinvertebrate 

Fate and risk of pesticides, pharmaceuticals, illicit drugs, and personal care products in the Iberian river basins of Ebro and Llobregat: Challenges and solutions using advanced treatment technologies in a European context

Preparation of catalysts using thin film (TF) techniques is not used yet in heterogeneous catalysis because TF technologies are generally considered as incompatible with the preparation of sufficiently large surface areas. Moreover catalytic loading of large-sized reactors is not possible. These arguments, however, do not hold for the proton exchange membrane fuel cell (PEMFC) application. The TF coating technology for supported catalysts can be parallelized and scaled, with the size of the deposition facility being the only limitation. Most importantly, however, high-surface-area nanoporous catalyst films can indeed be prepared by suitable deposition techniques.Platinum is the most versatile element in catalysis, but it is rare and its high price limits large-scale applications, for example in fuel cell technology. Still, conventional catalysts use only a small fraction of the Pt content, i.e. those atoms located at the catalyst's surface. To maximize the noble metal efficiency, Pt should be atomically dispersed and located at the very surface layer of the material. Such atomically dispersed Pt surface species can indeed be prepared with exceptionally high stability. We identify a specific structural element, a ceria �nanopocket�, which binds Pt2+so strongly that it withstands sintering and bulk diffusion. These new materials may help to reduce the demand for noble-metals in catalytic applications. One example is the deposition of Pt doped cerium oxide TFs on nanostructured carbon surfaces.The new class low cost catalyst was prepared by magnetron sputtering deposition of Pt2+ doped cerium oxide TF as anode and Pt-Co sputtered alloy TF as cathode. The PEMFC test results showed that the thin film made PEM single FC revealed high stability and power density of 150 mW/cm2 with 50 �g of Pt per 1 cm2 of MEA (2 �g and 48 �g Pt/cm2 for anode and cathode, respectively).

Thin film catalysts for PEMFCs

Transition metal phosphides, and in particular Ni2P/SiO2, are a new class of catalysts highly active for hydrodesufurization and hydrodenitrogenation reactions of oil fractions. However, the Ni2P/SiO2synthesis temperature is very high for industrial standards (~ 993 K).In this work, different loadings of Pd (0.1, 0.5, 1.0%) were incorporated to a NixPyOz/SiO2 sample aiming the lowering of the transformation temperature phosphate ? phosphide. Temperature-programmed reduction results show that while the reduction profile of the NixPyOz/SiO2 sample presents only one peak with maximum at 993 K, the profile of the sample containing 1% Pd, 1% Pt, or 1% Rh presents such a maximum located at 772 K. The effects of the reduction temperature on the phosphorous K-edge were studied in situ by X-Ray Absorption Near Edge Structure (XANES) also showing, in agreement with TPR results, that the noble metal presence leads to a substantial decrease in the NixPyOz/SiO2 ? Ni2P transformation temperature, as shown in Figure 1.The temperature decrease can be associated with the hydrogen spillover phenomenon that occurs on the noble metal particles giving raise to atomic hydrogen, which greatly reduces the reduction temperature. Thiophene HDS results indicate that after the reduction step, the noble metals do not participate in the reaction.The nature of the spillover phenomen was studied and lead to the conclusion that the noble metal particle has to be in close contact with the phopsphate phase submitted to reduction in order to have a decrease in the synthesis temperature.

Reduction of the synthesis temperature of Ni2P/SiO2 by noble metals addition

248th National Meeting (2014)

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