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    Wyświetlanie 1-13 z 13
    Tytuł:
    Precipitation Processes during Non-Isothermal Ageing of Fine-Grained 2024 Alloy
    Autorzy:
    Kozieł, J.
    Błaż, L.
    Włoch, G.
    Sobota, J.
    Lobry, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/352499.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    AA2024 alloy
    scrap metal milling
    structure refining
    powder metallurgy
    precipitation hardening
    Opis:
    Mechanical alloying and powder metallurgy procedures were used to manufacture very fine-grained bulk material made from chips of the 2024 aluminum alloy. Studies of solution treatment and precipitation hardening of as-received material were based on differential scanning calorimetry (DSC) tests and TEM/STEM/EDX structural observations. Structural observations complemented by literature data lead to the conclusion that in the case of highly refined structure of commercial 2024 alloys prepared by severe plastic deformation, typical multi-step G-P-B →θ” →θ’ →θ precipitation mechanism accompanied with G-P-B →S” →S’ →S precipitation sequences result in skipping the formation of metastable phases and direct growth of the stable phases. Exothermic effects on DSC characteristics, which are reported for precipitation sequences in commercial materials, were found to be reduced with increased milling time. Moreover, prolonged milling of 2024 chips was found to shift the exothermic peak to lower temperature with respect to the material produced by means of common metallurgy methods. This effect was concluded to result from preferred heterogeneous nucleation of particles at subboundaries and grain boundaries, enhanced by the boundary diffusion in highly refined structures. Transmission electron microscopy and diffraction pattern analysis revealed the development of very fine Al4C3 particles that grow due to the chemical reaction between the Al matrix and graphite flakes introduced as a process control agent during the preliminary milling of chips. Al4C3 nano-particles are formed at high temperatures, i.e. during hot extrusion and the subsequent solution treatment of the samples. Highly refined insoluble particles such as aluminum carbide particles and aluminum oxides were found to retard recrystallization and reduce recovery processes during solution treatment of preliminarily milled materials. Therefore, the as-extruded material composed of a milled part and chip residuals retained its initial bimodal structure in spite of solution heat treatment procedures. This points to a high structural stability of the investigated materials, which is commonly required for new technologies of high-strength Al-based materials production.
    Źródło:
    Archives of Metallurgy and Materials; 2016, 61, 1; 169-176
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Precipitation Processes and Mechanical Properties of Aged Inconel 718 Alloy after Annealing
    Autorzy:
    Maj, P.
    Adamczyk-Cieślak, B.
    Slesik, M.
    Mizera, J.
    Pieja, T.
    Sieniawski, J.
    Gancarczyk, T.
    Dudek, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/352832.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    inconel 718
    mechanical properties
    heat treatment
    Opis:
    Inconel 718 is a precipitation hardenable nickel-iron based superalloy. It has exceptionally high strength and ductility compared to other metallic materials. This is due to intense precipitation of the γ’ and γ” strengthening phases in the temperature range 650-850°C. The main purpose of the authors was to analyze the aging process in Inconel 718 obtained in accordance with AMS 5596, and its effect on the mechanical properties. Tensile and hardness tests were used to evaluate the mechanical properties, in the initial aging process and after reheating, as a function of temperature and time respectively in the ranges 650°-900°C and 5-480 min. In addition, to link the mechanical properties with the microstructure transmission microscopy observations were carried out in selected specimens. As a result, factors influencing the microstructure changes at various stages of strengthening were observed. The authors found that the γ’’ phase nucleates mostly homogenously in the temperature range 650-750°C, causing the greatest increase in strength. On the other hand, the γ’ and δ phases are formed heterogeneously at 850°C or after longer annealing in 800°C, which may weaken the material.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 3; 1695-1702
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing
    Autorzy:
    Górka, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/355934.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hardening phases
    precipitation processes
    TMCP steel
    weld
    HAZ
    Opis:
    This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by dispersive (Ti,Nb)(C,N) precipitates (being between several and less than twenty nanometers in size). In arc welding, depending on a welding method and linear energy, an increase in the base material in the weld is accompanied by the increased concentration of hardening microagents in the weld. The longer the time when the base material remains in the liquid state, the greater the amount of microagents dissolved in the matrix. During cooling, such microagents can precipitate again or remain in the solution. An increase in welding linear energy is accompanied by an increase in the content of hardening phases dissolved in the matrix and, during cooling, by their another uncontrolled precipitation in the form of numerous fine-dispersive (Ti,Nb)(C,N) precipitates of several nm in size, leading to a dislocation density increase triggered by type 2 internal stresses.
    Źródło:
    Archives of Metallurgy and Materials; 2017, 62, 1; 321-326
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kinetyka procesów wydzieleniowych w stalach maraging podczas krótkotrwałego starzenia
    Kinetics of precipitation processes in maraging steels during short-term ageing
    Autorzy:
    Burian, W.
    Marcisz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/181913.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Metalurgii Żelaza im. Stanisława Staszica
    Tematy:
    stal maraging MS350
    kinetyka procesu wydzieleniowego
    obliczenia termodynamiczne
    MS350 maraging steel
    precipitation process kinetics
    thermodynamic calculations
    Opis:
    W artykule przedstawiono wyniki symulacji numerycznej procesu wydzieleniowego oraz badań mechanicznych i mikrostrukturalnych stali MS350 po starzeniu. Celem badań była analiza możliwości uzyskania wymaganych wysokich właściwości mechanicznych w wyniku zastosowania krótkich czasów starzenia w dobranej do tego procesu temperaturze. Przeprowadzone symulacje numeryczne kinetyki wydzielania cząstek umacniających w stali MS350 dały zgodność z obserwacjami doświadczalnymi, co potwierdza możliwość wykorzystania metod numerycznych do projektowania procesu obróbki cieplnej stali maraging.
    This article presents the results of numerical simulation of precipitation process as well as mechanical and microstructural investigations of MS350 steel after aging. The purpose of the investigations was the analysis of possibility to obtain high mechanical properties due to use of short-time aging at a temperature selected for this process. The numerical simulations of precipitation kinetics of reinforcing particles in MS350 steel have provided the compliance with experimental observations, which confirms the possibility to use numerical methods for designing the maraging steel heat treatment process.
    Źródło:
    Prace Instytutu Metalurgii Żelaza; 2013, T. 65, nr 2, 2; 8-14
    0137-9941
    Pojawia się w:
    Prace Instytutu Metalurgii Żelaza
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Role of precipitation processes in development of favourable combination of high strength and ductility of advanced bainitic steels
    Rola procesów wydzieleniowych w kształtowaniu korzystnej kombinacji wytrzymałości i ciągliwości zaawansowanych stali bainitycznych
    Autorzy:
    Kuziak, R.
    Kania, Z.
    Krztoń, H.
    Skupień, P.
    Radwański, K.
    Pidvysots`ky, V.
    Mazur, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/182237.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Metalurgii Żelaza im. Stanisława Staszica
    Tematy:
    carbonitrides
    precipitation strengthening
    numerical modeling
    bainitic steel
    węgliko-azotki
    umocnienia wydzieleniowe
    modelowanie numeryczne
    stal bainityczna
    Opis:
    The paper deals with the analysis of the precipitation processes of carbo-nitrides in bainitic steels aimed at their effect on austenite microstructure evolution during thermomechanical processing and precipitation strengthening in bainitic ferrite. The commercial ThermoCalc and Prisma computer programs were used for this purpose. The investigated steels contained 0.1%C, 2%Mn, and varying content of Ti and Nb additions, including: 0.12%Ti, 0.18%Ti, 0.13%Ti + 0.035%Nb. The best effect in terms of austenite grain growth prevention and precipitation strengthening was found for the steel microalloyed with Ti alone in the amount of 0.18%.
    Artykuł dotyczy analizy procesów wydzielenia węglikoazotków w stalach bainitycznych wpływających na ewolucję mikrostruktury austenitu podczas obróbki cieplno-mechanicznej i umacniania wydzieleniowego ferrytu bainitycznego. Do realizacji tego celu wykorzystane zostały komercyjne programy komputerowe ThermoCalc i Prisma. Badane stale zawierały 0.1% C, 2% Mn i zmienną zawartość dodatków Ti i Nb, w tym: 0.12% Ti, 0.18% Ti, 0.13% Ti + 0.035% Nb. Najlepszy efekt w zakresie zapobiegania rozrostu ziarna austenitu i umacniania wydzieleniowego zaobserwowano dla stali mikrostopowej z dodatkiem tylko Ti w wysokości 0.18%.
    Źródło:
    Prace Instytutu Metalurgii Żelaza; 2015, T. 67, nr 2, 2; 8-20
    0137-9941
    Pojawia się w:
    Prace Instytutu Metalurgii Żelaza
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ewolucja mikrostruktury i właściwości użytkowych austenitycznej stali X8CrNiTi18-10 (T321H) podczas długotrwałej eksploatacji w warunkach pełzania
    Evolution of microstructure and essential characteristics of austenitic steel X8CrNiTi18-10 (T321H) after long-term creep service
    Autorzy:
    Purzyńska, H.
    Dobrzański, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/182066.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Metalurgii Żelaza im. Stanisława Staszica
    Tematy:
    stal austenityczna
    pełzanie
    długotrwała eksploatacja
    trwałość resztkowa
    stopień wyczerpania
    procesy wydzieleniowe
    austenitic steel
    creep
    long-term service
    residual strength
    exhaustion degree
    precipitation processes
    Opis:
    Zmiany mikrostruktury, podstawowych właściwości wytrzymałościowych oraz odporności na pełzanie austenitycznej stali X8CrNiTi18-10 (T321H) po długotrwałej eksploatacji w warunkach pełzania. Opis procesu degradacji tej stali podczas długotrwałego pełzania. Ocena wpływu rodzaju i ilości występujących wydzieleń oraz struktury dyslokacyjnej na odporność na pełzanie (resztkowa wytrzymałość na pełzanie, szybkość pełzania) i stopień wyczerpania. Model degradacji mikrostruktury w wyniku eksploatacji w warunkach pełzania w odniesieniu do stopnia wyczerpania. Sekwencja kolejnych stadiów rozwoju procesu wydzieleniowego stali X8CrNiTi18-10 eksploatowanej w warunkach pełzania w zależności od stopnia wyczerpania. Klasy struktury w zależności od stopnia rozwoju procesów wydzieleniowych i struktury dyslokacyjnej w powiązaniu ze stopniem wyczerpania. Sposób klasyfikowania stanu materiału na podstawie zmian w strukturze w oparciu o procesy składowe w odniesieniu do stopnia wyczerpania. Metodologia oceny austenitycznej stali X8CrNiTi18-10 po eksploatacji w warunkach pełzania na podstawie oceny stanu mikrostruktury. Stan mikrostruktury i poziom właściwości użytkowych po eksploatacji w warunkach pełzania a stopień wyczerpania.
    Changes in microstructure of basic strength properties and creep resistance of austenitic steel X8CrNiTi18-10 (T321H) after long-term service under creep conditions. Description of degradation process for this steel during long term creep. Evaluation of the effect of the type and quantity of the occurring precipitation and the form of dislocation structure on creep resistance (residual creep resistance, creep rate) and exhaustion degree. Microstructure degradation model as a result of use under creep conditions in relation to exhaustion degree. Sequence of subsequent development stages of precipitation process for the X8CrNiTi18-10 steel service under creep conditions depending on exhaustion degree. Structure class depending on the development stage of precipitation processes and dislocation structure In relation to exhaustion degree. Classification of the state of material pertaining to changes in structure based on constituent processes in relation to exhaustion degree. Evaluation methodology for austenitic steel X8CrNiTi18-10 after service under creep conditions based on the assessment of the state of microstructure. State of microstructure and level of essential characteristics after use under creep conditions vs exhaustion degree.
    Źródło:
    Prace Instytutu Metalurgii Żelaza; 2017, T. 69, nr 3, 3; 11-38
    0137-9941
    Pojawia się w:
    Prace Instytutu Metalurgii Żelaza
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Precipitation amounts triggering landslide processes in the western part of the Nałęczów Plateau (Lublin Upland, Poland)
    Autorzy:
    Demczuk, Piotr
    Zydroń, Tymoteusz
    Szafran, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/15805023.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    slope stability
    shallow landslide
    rainfall thresholds
    loess
    the Nałęczów Plateau
    Opis:
    This study covers the western part of Poland’s loess Nałęczów Plateau (Kazimierz Dolny, Zbędowice). Mass movements in the Lublin Upland occur during periods of increased precipitation or after a snowy and cold winter. To date, there are no comprehensive studies on active (precipitation, hydrology, vegetation, land use, anthropogenic factors) or passive factors (lithology, slope angle) causing such geohazards in this region. This area’s formations are characterised by high sensitivity to even small changes in moisture content; thus, their geotechnical parameters deteriorate as a result of precipitation or rising groundwater levels. The calculations in this study were chosen to determine the time necessary for ground response to external factors, in addition to determining the impact of these factors on decreases in the factor of safety (FS). Based on calculations in GeoStudio software, the impacts of rainfall totals and duration on slope failure, interpreted as an event where the FS falls below 1.0, were analysed. Accordingly, the threshold rainfall value was determined as the total rainfall at the time of slope failure. The study’s results indicate that loess covers are characterised by average water permeability, relatively high internal friction angles and low cohesion, which, combined with high slope inclination, favour landslide formation even when the slope is only partially saturated. The most unfavourable stability conditions occur at the beginning of spring, indicating that loess stability is significantly affected by snowmelt and precipitation at the beginning of the vegetation season, as well as the occurrence of episodic intense precipitation during the summer.
    Źródło:
    Quaestiones Geographicae; 2022, 41, 3; 33-51
    0137-477X
    2081-6383
    Pojawia się w:
    Quaestiones Geographicae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the Local Precipitation Trends in the Podkarpackie and Lubuskie Voivodeships
    Autorzy:
    Kubiszyn, Katarzyna
    Powiązania:
    https://bibliotekanauki.pl/articles/27314853.pdf
    Data publikacji:
    2023
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    precipitation local
    Mann-Kendall test
    precipitation map
    drainage system
    erosion processes
    landslide prevention
    Podkarpackie Voivodeship
    Lubuskie Voivodeship
    opady lokalne
    Test Manna-Kendalla
    mapa opadów
    system odwadniający
    procesy erozyjne
    zapobieganie osuwiskom
    województwo podkarpackie
    województwo lubuskie
    Opis:
    The type of precipitation is one of the factors taken into consideration when deciding on the most optimal drainage system. Drainage systems are used to prevent the landslides caused by water erosion. Rainfall affect the rate of infiltration and the intensity of surface runoff and thus the occurrence, course and effectiveness of erosion processes [1, 2, 3]. Knowledge of local precipitation trends will help to apply precautions and thus minimise the risk of adverse events such as landslides. What is more it can help more effectively manage projects risks and costs. The aim of this study was to analyse more than 30 years of data from daily rainfall measurements from the Podkarpackie Voivodeship and to check whether the occurrence of precipitation is a random event or whether it indicates long-term trends that may affect changes in ground stability. The non-parametric Mann-Kendall test and correlation test were used for the analysis.
    Źródło:
    Civil and Environmental Engineering Reports; 2023, 33, 1; 122--138
    2080-5187
    2450-8594
    Pojawia się w:
    Civil and Environmental Engineering Reports
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Causes of periodical rainfall distribution and long-term forecast of precipitation for Lankaran, Azerbaijan
    Autorzy:
    Mammadov, A.
    Rajabov, R.
    Casanova, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/108455.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Meteorologii i Gospodarki Wodnej - Państwowy Instytut Badawczy
    Tematy:
    rainfall distribution
    synoptic processes
    atmospheric forces
    harmonic analysis
    baric gradient
    opady
    rozkład opadów
    prognoza długoterminowa
    Azerbejdżan
    Opis:
    Irregular rainfall distribution is receiving considerable attention. The amount of rainfall for one region can account for 500-600 mm, sometimes 1000 mm. For example, in the year 1985, Zagtala in Azerbaijan received 716 mm of rainfall, while in 1988, 2004 and 2008 - 1151, 1306 and 661 mm, respectively, were measured. In Lankaran 2061 mm were measured in 1982 and 470 mm in 1999. Generally, rainfall distribution differs across the Republic of Azerbaijan. In this study, the physical side of such variations was clarified. In relation to that, the movement speed of the atmosphere in regard of the rotation of the Earth was analyzed, showing that the difference in rainfall distribution, according to the time structure, is connected to the direction change of the atmospheric movement. Generally, the reasons for atmospheric movements cannot be identified as the rotation movement of the earth, mainly because both environments show different activities. While the processes happening in the atmosphere often change, influenced by the pressure gradient, the rotation movement of the earth is more stationary. We also evaluated the rainfall forecast method for the region Lankaran. Taking into account its simplicity, the Shuster method was used. Observation data was divided into stationary and casual elements. Selection of periodicals was determined by separation of long term meteorological data into harmonic functions. By accepting the variation, the coefficient casual item was added.
    Źródło:
    Meteorology Hydrology and Water Management. Research and Operational Applications; 2018, 6, 2; 39-43
    2299-3835
    2353-5652
    Pojawia się w:
    Meteorology Hydrology and Water Management. Research and Operational Applications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation on the course of complex processes carried out in vortex impinging jet reactors
    Autorzy:
    Wojtas, K.
    Rybałtowska, A.
    Witkowski, D.
    Makowski, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/115849.pdf
    Data publikacji:
    2015
    Wydawca:
    Fundacja na Rzecz Młodych Naukowców
    Tematy:
    jet reactor
    mixing
    chemical reaction
    precipitation
    numerical simulation
    reaktor strumieniowy
    mieszanie
    reakcja chemiczna
    osad
    symulacja numeryczna
    Opis:
    The paper presents an application of CFD simulations to predict a course of complex processes carried out in jet reactors. In this work the simulations results were verified with PIV and PLIF techniques and validated by comparing model predictions with experimental data for fast parallel chemical test reactions. Experimental results of BaSO4 precipitation in jet reactors are also discussed.
    Źródło:
    Challenges of Modern Technology; 2015, 6, 4; 31-35
    2082-2863
    2353-4419
    Pojawia się w:
    Challenges of Modern Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fluorki w środowisku wodnym – zagrożenia i metody usuwania
    Fluorine in the water environment - hazards and removal methods
    Autorzy:
    Bodzek, M.
    Konieczny, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/297154.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    water treatment
    fluoride removal
    coagulation
    precipitation
    adsorption
    membrane processes
    uzdatnianie wody
    usuwanie fluorków
    koagulacja
    wytrącanie
    adsorpcja
    procesy membranowe
    Opis:
    High fluorine concentrations in aquatic environment, even above 30 mg/L, are often detected in many parts of the world. Due to fluorine effects on health, World Health Organization (WHO) as well as national health authorities have established its maximum permissible concentration in drinking water at the level of 1.5 mg/L. This review article aims to provide detail information on researchers’ efforts in the field of fluorides removal during potable water production. The contaminant elimination methods have been broadly divided in three sections, i.e. coagulation/precipitation, adsorption and membrane techniques. Both, precipitation with the use of calcium salts or coagulation with aluminum sulphate and ferric salts followed by sedimentation are used for fluorine removal. In electrocoagulation, a coagulant is generated in situ by means of oxidation of anode usually made of aluminum or iron. The removal of fluorides from water and wastewater can be performed with the use of many different types of adsorbents, which are either applied already at industrial scale or still tested in the laboratory or pilot scale. The adsorption on activated aluminum oxide is already a common technology of fluorine removal from water and wastewater, and it is also indicated as the one of the best available technique (BAT) in this field. However, the adsorbent price is relatively high, while its efficiency mostly depends on pH and co-ions presence. Recently, a lot of effort has been devoted to develop an effective method of aluminum oxide modification with the use of metals’ oxides impregnation, which reveal significant defluoridation efficiency. The applicability of carbon based sorbents is less efficient than of aluminum compounds, hence a number of studies on modification of carbon based materials towards defluoridation improvement are carried out. The special attention is dedicated to carbon nanotubes. Among many natural materials, which are usable to fluorine adsorption, many different types of clays and minerals have been tested. Biosorbents, especially modified chitosan, also offer promising results in fluorine removal process. Additionally, a group of waste materials, which contain metal oxides, have also been examined to fluorides concentration decrease in contaminated aqueous streams, and those can be considered as alternative cheap sorbents. Synthetic layered double hydroxides (LDHs), hydrocalcite like compounds and nanosorbents have also gained a lot of attention as potential fluorine adsorbent, as they reveal high affinity toward the contaminant. Among membrane techniques reverse osmosis, nanofiltration, ultrafiltration in integrated systems, electrodialysis and Donnan dialysis have been discussed. The most important benefits offered by membrane processes are very high removal efficiency (up to 98%), single stage treatment, simultaneous water disinfection and low requirement for additional chemicals. However, the removal of other anions present in treated water is a serious disadvantage of those techniques, as it results in the need of water remineralization to assure the proper quality of finally produced potable water. Additionally, membrane processes are quite expensive due to relatively high initial concentrated solution containing fluorine may become a significant problem.
    Występowanie fluorków (F-) w wodach naturalnych jest związane z ich obecnością w skorupie ziemskiej, jak również aktywnością przemysłową człowieka. O ile obecność jonów F- w wodzie do picia w ilości 0,5÷0,7 mg/l zabezpiecza przed próchnicą zębów, o tyle ich nadmiar jest uważany za poważny problem zdrowotny. Regularne spożywanie wysoce fluorowanej wody, zawierającej 1,5÷4 mg F/l, wywołuje wiele chorób związanych z tkanką kostną (fluoroza, artretyzm i osteoporoza), chorobę Alzheimera, utratę pamięci i inne neurologiczne dolegliwości. Według World Health Organization, a także polskich przepisów, maksymalne stężenie fluorków w wodzie do picia nie może przekraczać 1,5 mg/l, a rekomendowany jest zakres 0,5÷1 mg/l. Opracowano szereg metod usuwania fluorków, które można podzielić na trzy grupy procesów: koagulacja i wytrącanie, membranowe techniki separacji oraz adsorpcja/wymiana jonowa.
    Źródło:
    Inżynieria i Ochrona Środowiska; 2018, 21, 2; 113-141
    1505-3695
    2391-7253
    Pojawia się w:
    Inżynieria i Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Skuteczność usuwania fluorków z roztworów wodnych metodami konwencjonalnymi i technikami membranowymi
    Conventional and membrane techniques of fluoride removal from aqueous environment
    Autorzy:
    Majewska-Nowak, K.
    Grzegorzek, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/237868.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Zrzeszenie Inżynierów i Techników Sanitarnych
    Tematy:
    oczyszczanie wody
    fluorki
    koagulacja
    wymiana jonowa
    adsorpcja
    strącanie
    procesy membranowe
    water treatment
    fluorides
    coagulation
    ion-exchange
    adsorption
    precipitation
    membrane processes
    Opis:
    Zanieczyszczenie wód powierzchniowych i podziemnych związkami fluoru jest problemem występującym w wielu regionach świata. Związki te mogą pochodzić zarówno ze źródeł antropogenicznych, jak i naturalnych. Niewielkie ilości fluorków działają korzystnie na rozwój kości i zębów, jednakże ich większe ilości w spożywanej wodzie wpływają szkodliwe na zdrowie człowieka. Zgodnie z wytycznymi WHO oraz polskimi przepisami, zawartość fluorków w wodzie przeznaczonej do spożycia nie może przekraczać 1,5 gF–/m3. Z tego powodu poszukuje się coraz skuteczniejszych i bardziej ekonomicznych metod defluoryzacji wody. Fluorki mogą być usunięte ze środowiska wodnego różnymi metodami fizyczno-chemicznymi, takimi jak adsorpcja, koagulacja, strącanie, wymiana jonowa, a także w procesach membranowych. W pracy omówiono przykłady procesów i technologii eliminacji flourków, z uwzględnieniem ich ograniczeń wpływających na skuteczność usuwania jonów fluorkowych z roztworów wodnych. Wykazano, że stopień usunięcia fluorków w różnych procesach technologicznych zależy przede wszystkim od takich czynników, jak pH roztworu, początkowa zawartość jonów F–, obecność jonów współtowarzyszących, rodzaj adsorbentu czy też właściwości membrany. Wyniki badań wskazują, że realizacja procesu defluoryzacji wody w optymalnych warunkach może zapewnić skuteczność usuwania fluorków przekraczającą 90%.
    Fluoride contamination of surface and groundwaters is frequently observed around the world. Fluorides may originate from both anthropogenic and the natural sources. In small amounts, they are beneficial for bone and teeth development. However, higher concentrations in drinking water are harmful to human health. According to WHO guidelines, the fluoride content in drinking water cannot exceed 1.5 gF–/m3. Therefore, more effective and economic defluoridation methods are sought. Fluorides can be removed from water environment by various physico-chemical methods such as adsorption, coagulation, precipitation, ion-exchange as well as the membrane processes. Examples of fluoride elimination processes and techniques are discussed, taking account of their limitations affecting the efficacy of fluoride removal from water solutions. It was demonstrated that the extent of fluoride removal in different technological processes primarily depends on solution pH, the initial F– ion concentration, presence of coexisting ions, adsorbent type and membrane properties. The study results indicate that under optimal operational conditions the fluoride removal efficacy may exceed 90%.
    Źródło:
    Ochrona Środowiska; 2016, 38, 1; 29-37
    1230-6169
    Pojawia się w:
    Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sekularne i ekstremalne procesy erozji wodnej gleb na Pojezierzu Drawskim
    Secular and extreme soil erosion processes in the Drawskie Lakeland
    Autorzy:
    Majewski, Mikołaj
    Powiązania:
    https://bibliotekanauki.pl/articles/295194.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Geomorfologów Polskich
    Tematy:
    gleba
    erozja wodna
    proces sekularny
    proces ekstremalny
    Pojezierze Drawskie
    warunki meteorologiczne
    rzeźba terenu
    litologia
    temperatura powietrza
    opady atmosferyczne
    klimat
    pokrywa śnieżna
    przemarznięcie gruntu
    soil
    water erosion
    secular process
    extreme process
    Drawskie Lakeland
    meteorological conditions
    relief of the terrain
    lithology
    air temperature
    precipitation
    climate
    ice sheets
    Opis:
    Soil erosion by water is one of the most important factors affecting contemporary landscape changes within the lowland geoecosystems in Central Europe. Soil erosion by water mainly depends on: rainfalls (especially its intensity and erosivity), length of slope and its inclination, type of cultivation and usage of land, anti-erosion treatments and susceptibility of soils to erosion. The aim of conducted research was to evaluate conditioning and magnitude of secular and extreme soil erosion processes in the Drawsko Lakeland with special considering of rainfall erosivity index (EI30). The main goal was realised through several research tasks. The first task involved examination of surface runoff and slope wash conditionings, course and quantity in the testing plot located within the Chwalimski Potok catchment. The second task was related to evaluate rainfall impact to soil erosion by water processes. It was realised by computation rainfall characteristics: intensity, kinetic energy and erosivity. In order to assess secular and extreme soil erosion impact to land relief changes, research were provided with additional details by conducting three field experiments with simulated rainfall. Stationary observation and quantitative researches of soil erosion (at testing plots) have been conducting within the Chwalimski Brook catchment for three hydrological years (2012–2014). The slope with the test area is located within the 1st order catchment being a subsystem of the Młynski Brook catchment and then followed by the upper Parsęta catchment. This area covers 4.8 hectares and is characterised by short slopes with small height variances up to 10 meters. Historically, the area was covered with agricultural crops, currently they cover about 10% of the area. The slope is covered with gleyic retisols and its average inclination is about 4 degrees with its south-east exposure. The measuring system of soil erosion covered 5 testing plots with different agricultural use (bare fallow, meadow, potatoes, spring and winter crops). Plots are 42 metres long and 4 metres width. In the bottom edge of each plot catchers with volume of 800 dm3 were installed. In this research, only data from black fallow were considered. Such tillage is recognised as a standard in soil erosion studies. Two experiments have been conducted in this testing plot. The third one has been conducted on slope located within an area of undulated morainic plateau in the Kłuda catchment. The slope is characterised by greater height variances than in Chwalimski Brook catchment. The slope, where the experiment has been conducted, is situated within local closed depression and is covered by sands underlain by boulder clay. Its average slope is about 10° with its southwest exposure. Although annual precipitation in the three-year measurement period was comparable with mean value from multi-year period (1987–2014), its intensity and erosivity were distinguishably lower. Such rainfall conditions are not favourable for extreme soil erosion by water processes, thus any relief forms from such geomorphological processes were not observed in the Drawsko Lakeland. Due to lack of that kind of forms, in 2013 and 2014, three field experiments were conducted. The main aim of experiments was to evaluate the impact of high intensity rainfall on soil surface. The first experiment consisted of 5, the second and the third of 4 rainfall simulations. The rainfall was created by using a purpose-built rain simulator, consisting of 3 and 6 sprinklers placed around the testing plot. Despite the slope inclination in the Kłuda catchment was 2.5 times steeper than Chwalimski Potok’s slope, surface runoff attained smaller volume, because of remarkably higher infiltration rate. In 2012–2014, surface runoff and soil loss has occurred 8 times each year. The maximal monthly surface runoff volume was registered in February 2012, and it equalled 10.1 dm3 m−2 and the maximal soil loss value was registered in May 2013 and equalled 3,198 kg ha−1. Annual runoff volumes were between 31.2 dm3 m−2 in 2012 and 38.8 dm3 m−2 in 2013, whereas annual soil loss values ranged from 740 kg ha−1 in 2012 to 5,700 kg ha−1 in 2013. Soil erosion values caused by simulated rainfall during field experiments were similar or significantly higher than annual values. Surface runoff was between 31.2 dm3 m−2 in the first experiment and 34.2 dm3 m−2 in the second one, whilst soil loss was between 4,632 kg ha−1 and 8,637 kg ha−1. The achieved experiment results have been compared with soil erosion rate achieved from stationary observations. The results show that runoff and soil loss considerably increase during rainfalls with high amount, intensity and erosivity. Furthermore, individual extreme erosive events may exceed annual (secular) soil erosion processes. Conducted stationary research indicates that annual soil erosion primarily depends on individual rainfall and erosive events, which considerably exceed mean values. In order to evaluate the soil susceptibility to erosion by water in the Drawsko Lakeland, high resolution potential and actual soil erosion risk maps were prepared. The qualitative assessment of soil erosion risk was based on geoinformation technologies. The model considers following conditions affecting the size of soil erosion: slope steepness and aspect, topographic factor LS (unit upslope contributing area), lithology, rainfall erosivity (Modified Fournier Index calculated from monthly and annual precipitation data) and land use and land cover from Corine Land Cover 2006. To prepare the map of potential soil erosion risk, land use from Corine Land Cover was not considered. Thematic maps have been reclassified into a 4-degree division. The results of the soil erosion risk assessment in the Drawsko Lakeland reveal the fact that a majority of its area is characterized by moderate or low erosion risk levels. Areas with high erosion risk are mostly located in the northern part of the Lakeland. The achieved results from stationary observations and field experiments may indicate that the soil loss magnitude significantly increases during rainfall with higher intensity, greater totals and accumulated in time rainfall events. This may confirm the high potential of soil erosion by water processes of above- -average magnitude and intensity in the discharge of material from agricultural used slopes.
    Źródło:
    Landform Analysis; 2020, 39; 1-106
    1429-799X
    Pojawia się w:
    Landform Analysis
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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