Application of zeolites as fillers in mix asphalt

The aim of this paper is estimation of the effect of zeolites addition on properties of asphalt and examination of possible application of zeolites in mix asphalt as a filler. The addition of zeolites to the mix asphalt is one of the ways used for reduction of technological temperatures by asphalt foaming. At the same time the zeolite material replaces the filler. The paper presents the results of studies on the synthetic zeolite NaP1, natural zeolite- clinoptilolite and mineral filled

Learning curve or experience-related outcome : what really matters in paediatric laparoscopic pyeloplasty

Introduction: The process of improving one's skills over time is called a “learning curve”. This term has attracted great attention during the last decades, especially in relation to laparoscopic techniques. Aim: To assess the outcome of paediatric laparoscopic pyeloplasty (LP). Material and methods: Retrospective analysis of the consecutive LPs. The inclusion criteria: (1) children aged < 18 years, (2) transperitoneal approach, and (3) the same operating paediatric urologist (RC). Patients with a history of any procedure on the upper urinary tract were excluded. Any surgical reintervention during follow-up was defined as a failure. The outcomes of LPs performed before 2012 (G1) were compared to those conducted between 2012 and 2016 (G2). Fisher's exact test was used for statistical analysis. Results: Ninety patients met the inclusion criteria, and a total of 95 LPs were performed. The mean operation time was 155 min, and the mean hospitalisation period was 2.4 days. In G1, 19 patients underwent Anderson-Hynes LP, 16 had Fenger non-dismembered LP and two underwent vascular hitch. In G2, 54, 2 and 2 patients underwent these procedures, respectively. The overall success rate was 91.5%. There were six failures in G1 and three in G2 (p = 0.147). Of the Anderson-Hynes LPs, 1/19 in G1 and 3/58 in G2 required reintervention (p = 1). For Fenger LPs, this was 4/16 and 0/2, respectively (p = 1). Only one patient required reoperation after vascular hitch. Conclusions: The surgeons' learning curve reflects their experience with regard to the entire therapeutic process, but not exclusively their manual skills

Na-P1 zeolite synthesis and its crystalline structure ripening through hydrothermal process using coal combustion by-products as substrates

Energy industry sector is one of the major environment pollutants. This branch also generates significant amounts of by-products such as slugs, slug-ash mixtures, ashes and microspheres, which can be very harmful for the earth ecosystems. Statistically the microspheres (MIC) constitute from 0.6% to 2.5% of the total amount of post combustion wastes. MIC occurs mainly in fly ashes (less often in slugs) as the smallest, hollow, spherical particles. MIC is composed mainly of crystalline and amorphous aluminosilicate phases. The combustion conditions have strong influence on MIC composition. Mineral and chemical composition of MIC is very similar to F type of fly ashes; consequently there is a possibility to use them as substrates for zeolite synthesis. Zeolites are minerals from microporous, aluminosilicate group (Szala et al. 2015). Among others, they are characterized by specific channels and chambers occurrence in their structure, which results in a number of important features like: ion exchange, sorption, molecular sieve or catalytic properties. This is the reason for wide use of zeolites in numerous industrial sectors (Ahmaruzzaman 2010). The aim of this study is a synthesis of Na-P1 zeolite at semi-technical scale by conversion of microspheres under hydrothermal conditions in an alkaline medium. This study involves also research of Na-P1 zeolite structure ripening in order to optimize the synthesis conditions. Microspheres from Stalowa Wola Power Plant (Poland) were used as a substrate. For the synthesis of Na-P1 phase the following conditions were applied: 90 dm 3 of water, 15 kg of microsphere, 11 kg of sodium hydroxide (3 mol/dm 3 ), temperature: 80°C, and reaction time up to 26 h (Franus et al. 2014). The zeolite conversion was performed on semi-technical scale installation (Wdowin et al. 2014). During the conversion, samples were collected from the reactor after 2, 4, 6, 10, 14, 26 hours. To investigate the influence of time for zeolitization process efficiency these samples were analyzed in terms of chemical and mineral composition, structural and textural properties. The main attention was paid to the evolution of the Na-P1 unit cell parameters observed as a function of time (calculations and models were performed for every sample). The phase’s composition was determined with powder X-ray diffraction (XRD) method using a PANalytical X’pert MPD diffractometer (with a PW 3050/60 goniometer), Cu lamp, and a graphite monochromator. The analysis was performed within the angle range of 5–65 2θ. PANalytical X’Pert Highscore software was used to process the diffraction data. The identification of mineral phases was based on the PDF-2 release 2010 database formalized by the ICD and IZA-SC Database of Zeolite Structures. The experimental calculations of the unit cell parameters were performed using UnitCell software. The spatial model of Na-P1 zeolite cell was prepared using Mercury 3.7 Windows software. The morphological forms and the chemical composition of the main mineral components were determined with scanning electron microscope (SEM) FEI Quanta 250 FEG equipped with the SE detector and a system of chemical composition analysis based on energy dispersive X-ray-EDS of EDAX company. N 2 adsorption-desorption measurements were carried out at 77 K using ASAP 2020 volumetric adsorption analyzer (Micromeritics). The specific surface areas (S BET ) of the samples were evaluated using the standard Brunauer–Emmett–Teller (BET) method for nitrogen adsorption data in the range of relative pressure p / p 0 from 0.06 to 0.3. The total pore volumes were estimated from single-point adsorption at a relative pressure of 0.98. XRD data indicates that main phases in microsphere are amorphous aluminosilicate glass, mullite and quartz. The obtained product is dominated by Na-P1 phase. Experimental calculations of cell parameters and fabricated models confirm crystallographic similarity to Na-P1 pattern. Noteworthy is the fact that the unit cell parameters depend on reaction time. Calculations indicate that the cell parameters (walls length: a , b , c and cell volume) increase with time towards to pattern values. This phenomenon may be interpreted as a ripening of crystalline structure. An in-depth look at this matter can lead to better estimation of synthesis conditions, which have a significant impact to the total cost of zeolites production – especially at a larger scale. SEM shows progressive dissolution (also as a function of time) of aluminosilicate glass in favor of crystallization of zeolite phase. EDS analysis confirms similarity of chemical composition of the obtained samples to a standard Na-P1 zeolite. Calculated textural properties indicate increase of S BET with the reaction time. Simultaneously, the average pore diameters decrease. The S BET of synthetized Na-P1 was 4.62 m 2 /g after 2 h but it increased to 47.92 m 2 /g after 26 h. This is an effect of growing contribution of zeolite phase in relation to the initial substrates in the sample during the reaction time. The experimental conditions allowed synthesizing Na-P1 zeolite from microsphere particles in the prototype installation. Zeolitization process strongly influences the textural properties by increasing S BET and improving pore structure. The microsphere from Stalowa Wola Power Plant is a promising material for the synthesis of Na-P1 zeolite in the prototype installation. Still, the reaction parameters should be reconsidered, basing on the obtained results, in order to reduce the cost of the zeolite production as much as possible. This is required before proceeding to the full technical production scale. To observe increase of zeolite amount in entirety synthesis batch (and to link it with cell behavior) the Rietveld analysis will be provided

Microstructure, XRD and Mössbauer spectroscopy study of Gd doped BiFeO3

The results of fabrication process and characterization of Bi1-xGdxFeO3 (x = 0.05, 0.07, 0.10) ceramics are reported in the paper. The samples were prepared by standard solid state reaction method from the mixture of oxides: Bi2O3, Fe2O3 and Gd2O3. The influence of Gd substitution on the microstructure and density of Bi1-xGdxFeO3 was studied. Phase composition and structure of the obtained samples were investigated by Xray diffraction. It turns out that the Bi1-xGdxFeO3 solid solutions with x = 0.05 and 0.07 crystallize in trigonal structure characteristic of BiFeO3 compound. For the sample with x = 0.1, beside the major trigonal phase, 6% of orthorhombic phase typical for GdFeO3 was detected. Hyperfine interaction parameters were studied by Mössbauer spectroscopy. Mössbauer results proved that the spin cycloid characteristic of BiFeO3 compound gradually disappears when substituting Gd3+ ions at the Bi3+ sites

Theoretical description of hydrogen bonding in oxalic acid dimer and trimer based on the combined extended-transition-state energy decomposition analysis and natural orbitals for chemical valence (ETS-NOCV)

In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV’s revealed that the formation of hydrogen bonding is associated with the electronic charge deformation in both the σ—(Δρσ) and π-networks (Δρπ). It was demonstrated that σ-donation is realized by electron transfer from the lone pair of oxygen on one monomer into the empty \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rho_{H - O}^*$$\end{document} orbital of the second oxalic acid fragment. In addition, a covalent contribution is observed by the density transfer from hydrogen of H-O group in one oxalic acid monomer to the oxygen atom of the second fragment. The resonance assisted component (Δρπ), is based on the transfer of electron density from the π—orbital localized on the oxygen of OH on one oxalic acid monomer to the oxygen atom of the other fragment. ETS-NOCV allowed to conclude that the σ(O---HO) component is roughly eight times as important as π (RAHB) contribution in terms of energetic estimation. The electrostatic factor (ΔEelstat) is equally as important as orbital interaction term (ΔEorb). Finally, comparing β-dimer of oxalic acid with trimer we found practically no difference concerning each of the O---HO bonds, neither qualitative nor quantitative

Analiza środowiskowa nowatorskich sorbentów do sorpcji rtęci

The reduction of mercury emissions in currently existing coal-based power plant solutions by each method i.e. preliminary, primary and secondary (consisting of introducing coal into the combustion chamber and then removing mercury from the combustion gases arising from the combustion process) does not solve the problem of achieving the required limits by power plants. Therefore, the need has arisen to look for new, effective solutions. The results presented in the work concern the analysis of environmental benefits for the use of zeolites obtained from by-products of coal combustion such as fly ash (from hard coal and lignite) in technologies for removing gaseous forms of mercury. The tested zeolites were silver-modified X-type structures. The reference material in the considerations was active carbon impregnated with bromine – a commercially available sorbent on the market. The article considers environmental benefits resulting from the use of tested zeolites taking the product life cycle, sorbent efficiency and the possibility of its regeneration compared to activated carbon (AC/Br) into account. The LCA analysis was performed taking the estimated material and energy balances of the manufacturing processes into account. When comparing the production process of type X zeolite materials on the processing line and activated carbons in the amount necessary to capture 375 g Hg from exhaust gases, the LCA analysis showed that zeolites contribute to a lower potential impact on the environment. The advantage is that 5 times less zeolite sorbent than activated carbons is needed to capture the same amount of mercury. In addition, zeolite materials can be regenerated, which extends their life time.Redukcja emisji rtęci w obecnie istniejących rozwiązaniach elektrowni bazujących na węglu zarówno metodami wstępnymi, jak i metodami pierwotnymi oraz metodami wtórnymi polegającymi na wprowadzeniu węgla do komory paleniskowej, a następnie usuwaniu rtęci z gazów wylotowych powstałych w procesie spalania, nie rozwiązuje problemu osiągnięcia wymaganych limitów przez elektrownie, w związku z czym istnieje potrzeba poszukiwania nowych, efektywnych rozwiązań. Przedstawione w pracy wyniki dotyczą analizy korzyści środowiskowych dla zastosowania zeolitów otrzymywanych z ubocznych produktów spalania, jakimi są popioły lotne (z węgla kamiennego i brunatnego) w technologiach usuwania gazowych form rtęci. Badane zeolity stanowiły struktury typu X modyfikowane srebrem. Materiałem referencyjnym w rozważaniach był węgiel aktywny impregnowany bromem – komercyjnie dostępny na rynku sorbent. W artykule rozważono korzyści środowiskowe wynikające z zastosowania badanych zeolitów uwzględniając cykl życia produktu, wydajność sorbentu oraz możliwość jego regeneracji w porównaniu do węgla aktywnego (AC/Br). Analizę LCA dokonano, uwzględniając oszacowane bilanse materiałowe i energetyczne procesów wytwarzania. Przy porównaniu procesu produkcji materiałów zeolitowych typu X na linii technologicznej oraz węgli aktywnych w ilości niezbędnej do wychwycenia z gazów odlotowych 375 g Hg, analiza LCA wykazała, iż zeolity przyczyniają się do mniejszego potencjalnego wpływu na środowisko. Zaletą jest fakt, iż do wychwycenia tej samej ilości rtęci niezbędne jest 5 razy mniej sorbentu zeolitowego niż węgli aktywnych. Ponadto materiały zeolitowe dodatkowo można regenerować, co wydłuża ich czas życia

The Effects of Textural Parameters of Zeolite and Silica Materials on the Protective and Functional Properties of Polymeric Nonwoven Composites

Zeolites are micro- and mesoporous aluminosilicate minerals (both natural and industrially produced) widely used as catalysts and sorbents in domestic and commercial water purification and separation technologies. Their ability to selectively adsorb gases (i.e., water vapor, carbon dioxide, and sulfur dioxide removal) from an air stream makes them suitable for applications in odor reducing media used in filtering facepiece respirators (FFRs). FFRs are multilayer products in which the most important role is played by high-performance melt-blown electret nonwovens modified with activated carbon to adsorb malodorous compounds. Replacing carbon sorbents with zeolites could increase the efficiency of odor abatement, thus alleviating work-related hazards for individuals exposed to malodorous substances with adverse effects on human well-being. The objective of the present work was to analyze the influence of the textural parameters of zeolite and mesoporous silica materials on the protective and functional properties of polymeric nonwoven composites containing them. In our experiments, the longest breakthrough time against ammonia vapor was found for a nonwoven composite containing the inorganic mesoporous silica material type MCM-41. It was also characterized by high filtration efficiency against aerosols with solid and liquid dispersed phases (97% and 99% for sodium chloride and paraffin oil mist, respectively) at an airflow resistance of approximately 330 Pa. In turn, the composites containing the molecular sieve (SM-zeolite ZSM-5) exhibited the longest breakthrough time for acetone and cyclohexane vapors at the maximum allowable concentrations of 235 ppm and 81 ppm, respectively. Basic filtration tests showed that the composite was 97% effective against both test aerosols at an airflow resistance of 283.5 Pa