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EN
The process of sorption of chromium(III) ions with a stationary sorbent layer of bentonite clays was investigated. The main advantages of using bentonites in water purification technologies are described: powerful geological reserves, cheap process of rock extraction, easy preparation for transportation and use, possibility of using waste sorbents in other technologies that is why there is no need in costly regeneration. The influence of various factors (process duration, an adsorbent layer) on the degree of wastewater purification from chromium ions, the effect of pumping speed on the dynamic capacity of the sorbent was studied and the effective volume was determined. The adsorption efficacy increases with the increase of the adsorbent layer, what can be explained by the development of the active sorption surface. As the initial concentration of chromium ions increases, the time of appearance of the first traces of the contaminant at the exit of the column increases, as well as the total time to channeling. The results of the studies indicate a higher adsorption capacity of modified bentonite with respect to Cr3+ ions compared to its natural formula. The cleaning efficacy of the solution with a concentration of chromium ions of 0.5 g∙dm–3 is increased by 5% when using 15 g of modified bentonite and 6,5% in the case one uses 20 g compared to the natural form.
EN
Bentonite clay was utilized in this research as adsorbent element to remove the lead and copper ions from wastewater. Series of tests were performed at multiple parameters, such as pH solution, initial concentration of lead and copper ions, adsorbent mass, and contact time. The greatest removal was attained at pH 5, adsorbent weight of 0.5 g, initial heavy metal concentration of 10 mg/l, and a contact time of 60 minutes. The results revealed that bentonite clay is suitable in the removal of metal ions from polluted water. The ion exchange rate of lead was faster than that of copper. The isotherm for the adsorption of the lead and copper ions on bentonite clay was confirmed by the Freundlich and Langmuir isotherms which offered good consequences. The results indicated that bentonite was utilized as an efficient ion exchange element for the removal of heavy metal ions from polluted water. Fourier Transformed Infrared Spectrophotometer (FTIR) images of bentonite clay before and after adsorption showed the imbibition of metal ions by bentonite clay.
EN
The aim of this study was to present the results of the examinations of the structure and thermomechanical properties of PA6/NanoBent composite. NanoBent composites composed of minerals from the smectite group (mainly montmorillonite) were used for modification of polyamide 6. PA6 composite with content of 1, 3, 5% of NanoBent was prepared in a Theysohn TSK 75-N twin screw extruder. The samples were prepared using the injection technology by means of a Krauss-Maffei KM65-160 C1 injection molding machine. The samples of composites obtained at different injection temperatures and injection mold temperatures were used for the examinations. Degree of crystallinity was examined using the DSC method whereas the material structure was examined with an optical microscope. DSC studies showed a reduction in the value of the degree of crystallinity with the increasing content of nanofiller in the polymer material. The narrowing of the peak was recorded in the DSC thermograms for nanocomposites with greater percentage of the nanofiller. Dynamical properties of polyamide 6 nanocomposite were also determined in relation to temperature and frequency. The samples were bended at frequencies of 1 Hz and 10 Hz over the temperature range from –100°C to 180°C and the heating rate of 2K/min. A significant increase in storage modulus was observed for PA6 samples with the content of 5% of NanoBent obtained at the injection temperature of 270°C and mold temperature of 70°C. smaller size of spherulites and arrangement of structural elements in clusters along the line of polymeric material flow in the mold cavity at higher contents of NanoBent were observed during structural examinations of the composites.
4
Content available remote Bentonite-loess slurry for construction of diaphragm walls and bored piles
EN
Bentonite fluids are used in narrow excavations in technologies of slurry walls and bored piles. If bentonite is characterised by high liquid limit, production of support fluid with sufficiently high density and accompanying low viscosity is impossible. The aim of the presented research was to verify the usefulness of loess for modification of bentonite slurries. Various bentonite-loess mixtures and suspensions activated with sodium carbonate were tested. It was noted that an addition of loess results in a decrease in liquid limit of the bentonite-loess mixture. Testing of suspensions produced from different bentonite-loess mixtures enabled determination of the optimum sodium carbonate content as well as the minimum bentonite-loess mixture content in the suspension ensuring the required density. The influence of loess content on viscosity and water bleed was then investigated, which enabled determination of loess content range at which suspensions with the required density fulfil also the requirements regarding viscosity and bleed. It was ascertained that an addition of loess enables production of bentonite-loess slurries with adequate properties. Based on the presented results, a patent was obtained and production of bentonite-loess mixture for use in technology of slurry walls was initiated.
PL
Zawiesiny bentonitowe wykorzystuje się do wykonywania wykopów wąsko przestrzennych w technologii ścian szczelinowych, a także w technologii pali wierconych. Jeśli bentonit charakteryzuje się dużą granicą płynności, nie jest możliwe wytworzenie zawiesiny o wystarczająco dużej gęstości i małej lepkości. Celem badań było sprawdzenie przydatności lessu do modyfikowania właściwości zawiesin bentonitowych. Wykonano badania kompozycji bentonitowo-lessowych i zawiesin aktywowanych węglanem sodu. Stwierdzono, że dodatek lessu powoduje zmniejszenie granicy płynności kompozycji bentonitowo-lessowej. Badania zawiesin zawierających kompozycje bentonitowo-lessowe pozwoliły na określenie optymalnej zawartości węglanu sodu oraz niezbędnej ilości bentonitu i lessu w zawiesinie zapewniającej wymaganą gęstość. Następnie zbadano zależności pomiędzy zawartością lessu a lepkością umowną i odstojem zawiesin, co pozwoliło na określenie dodatku lessu, przy którym zawiesiny o wymaganej gęstości spełniają kryteria lepkości i odstoju. Stwierdzono, że dodatek lessu umożliwia uzyskiwanie zawiesin bentonitowo-lessowych o odpowiednich właściwościach. Na podstawie przedstawionych wyników badań uzyskano patent i uruchomiono produkcję kompozycji bentonitowo-lessowej do zawiesin przydatnych w technologii ścian szczelinowych.
5
Content available remote Wpływ modyfikacji bentonitu na jego właściwości adsorpcyjne
PL
Przeprowadzono kwaśną aktywację bentonitu za pomocą kwasu solnego, uzyskując wzrost powierzchni właściwej BET adsorbentu o 228 p.p. Zmianie uległy również inne parametry powierzchniowe, takie jak średnica i objętość porów, a także powierzchnia i objętość mikroporów. Impregnacja bentonitu nanometrycznym tlenkiem cyrkonu(IV) nie przyniosła zamierzonych efektów i przyczyniła się do pogorszenia właściwości adsorpcyjnych bentonitu. Efektywność adsorpcji określano, przeprowadzając testy adsorpcji siarkowodoru w warunkach beztlenowych. Skuteczność impregnacji bentonitu oceniano na podstawie obrazów powierzchni adsorbentów, wykonanych za pomocą skaningowego mikroskopu elektronowego (SEM).
EN
Com. bentonite was activated with HCl soln. to increase its sp. surface area by 228 percentage points (p.p.). Changes of diam., pore volume, as well as area and volume of micropores were also obsd. The impregnation of bentonite with nanometric ZrO₂ resulted in deterioration of the adsorption capacity of bentonite. The bentonite adsorbents were used for removal of H₂S from biogas under anaerobic conditions. The ZrO₂ modified bentonite was less efficient than the HCl-activated one, where 99% removal H₂S from N₂ stream was achieved.
6
Content available remote Efektywność sedymentacji zawiesin bentonitowych
PL
Przedstawiono kolejne kroki mające na celu zwiększenie efektywności sedymentacji dla wybranych zawiesin bentonitowych. Zawiesiny te zostały wybrane, ponieważ zachowanie ich cząstek podczas opadania jest związane ze specyficznym składem, właściwościami oraz skomplikowaną wewnętrzną strukturą bentonitu. Oznaczono rozkład wielkości ziaren, skład chemiczny i fazowy próbek bentonitowych, a także przeprowadzono przepływowy test sedymentacyjny.
EN
Three bentonites differing in the montmorillonite content were studied for grain size distribution, d., chem. and phase compn. Their water suspensions were sedimented under flow conditions. The exptl. detd. sedimentation efficiency was compared with that calcd. one according to the classical and fractal models. A much better match of exptl. results was obtained when the fractal model was used.
EN
Successful casting demands that during pouring of the foundry mould with molten metal the mould cavity suffers no deformation. This, in turn, demands the use of binding materials that can give the base sand adequate strength. The main bonding materials are clay binders. The foundry industry uses minerals rich in clay, such as kaolinite, halloysite, hydromica, montmorillonite, polygorskite, vermiculite and allophane. Due to their binding capacity, montmorillonites are the most interesting minerals of all the plastic clay rocks. The basic clay rock containing montmorillonite, used as a common binding material for traditional foundry sand mixtures, is bentonite. The domestic demand for raw bentonite materials is almost entirely satisfied by imports from Slovakia, Turkey, Italy, Germany and the Czech Republic, in order of import size. In Poland, the bentonite deposits occur in very small quantities. The exploitation of bentonites is carried out only in the Krzeniów deposit, where they constitute a mineral accompanying basalt. Much more common are bentonite clays containing in addition to smectites also a large amount of other clay minerals. The article presents the results of studies of the physico-chemical and mechanical properties of moulding sand mixtures containing pure bentonite, pure clay or hybrid bentonites which are a bentonite-clay mixture. Melting was also carried out to determine the effect of the type of binder on the surface quality of iron castings.
EN
This work is dedicated to the development of scientific technologies of wastewater purification of different industrial enterprises from chrome ions through adsorption with the help of bentonite from Cherkasy field under dynamic conditions. The prospects and efficacy of bentonite clays application for wastewater purification are confirmed by their advantages over other sorbents, that is: they win in accessibility, cost, and possibility of regeneration and multiple applications. The level of wastewater purification during adsorption with a stationary sorbent layer under static conditions and under conditions of perfect mixing at different concentrations of chromium ions (III) and quantities of the dosed sorbent was determined. The significant difference in the purification level ranges from 70–87% and is more dependent on the stock concentration of chromium ions. It was found that the purification time of the same volumes of solutions for low concentrations is almost twice shorter under constant stirring, and of the same level at the stock concentrations of 1500 mg/dm3. The technological schemes of wastewater purification from the heavy metal ions contamination were developed.
EN
Zeolites as a member of family of hydrated aluminosilicate minerals contains alkali and alkaline-earth metals. They are noted for their lability toward ion-exchange and reversible dehydration. Their framework structure encloses interconnected cavities occupied by large metal cations and water molecules. Bentonites are clays generated frequently from the alteration of volcanic ash, consisting predominantly of smectite minerals, usually montmorillonite. They present strong colloidal properties and its volume increases several times when coming into contact with water, creating a gelatinous and viscous fluid. The special properties of bentonite (hydration, swelling, water absorption, viscosity, thixotropy) make it a valuable material for a wide range of uses and applications. The purpose of this paper is to document an ability of a zeolite and bentonite to remove iron ions and various other pollutants from water. The surface analysis of zeolite and bentonite was performed by the very sensitive analytical device – XPS (X–ray photoelectron spectroscopy).
PL
Zeolity należą do rodziny uwodnionych minerałów glinowokrzemianowych, zawierających metale alkaliczne oraz alkaliczno-ziemne. Są zauważane ze względu na ich zdolność wymiany jonowej oraz odwrotnej dehydratacji. Ich struktura zawiera wewnętrznie połączone wgłębienia zajęte przez duże kationy metali oraz cząsteczki wody. Bentonity to iły tworzone często poprzez alterację popiołu wulkanicznego, zawierające głównie minerały smektytu a zazwyczaj montmorillonitu. Wykazują silne właściwości koloidalne a ich objętość wzrasta kilkukrotnie podczas wejścia w kontakt z wodą, tworząc w ten sposób galaretowatą i lepką ciecz. Specjalne właściwości bentonitu (hydratacja, puchnięcie, absorpcja wody, lepkość, tiksotropia) powodują, że jest to cenny materiał dla szerokiej gamy zastosowań. Celem tego artykułu jest udokumentowanie zdolności zeolitów oraz bentonitów do usuwania jonów żelaza oraz różnych innych zanieczyszczeń z wody. Analiza powierzchni zeolitu i bentonitu została wykonana za pomocą bardzo czułego urządzenia analitycznego – XPS (roentgenowska spektroskopia fotoelektronowa).
EN
Bentonites and clays are included in the group of drilling fluids materials. The raw materials are mainly clay minerals, which are divided into several groups, like montmorillonite, kaolinite, illite, biotite, muscovite, nontronite, anorthoclase, microcline, sanidine or rutile, differing in chemical composition and crystal lattice structure. Clay minerals have a layered structure forming sheet units. The layers merge into sheets that build up to form the structure of the mineral. The aim of the studies carried out in the ŁUKASIEWICZ Research Network - Foundry Research Institute is to explore the possibility of using minerals coming from Polish deposits. The article outlines the basic properties of hybrid bentonites, which are a mixture of bentonite clay called beidellite, originating from overburden deposits of the Turoszów Mine, and foundry bentonite from one of the Slovak deposits. As part of the physico-chemical tests of minerals, measurements included in the PN-85/H-11003 standard, i.e. montmorillonite content, water content and swelling index, were carried out. Additionally, the loss on ignition and pH chemical reaction were determined. Based on the thermal analysis of raw materials, carried out in the temperature range from 0 to 1000⁰C, changes occurring in these materials during heating, i.e. thermal stability in contact with liquid metal, were determined. Examinations of the sand mixture based on pure clay and bentonite and of the sand mixture based on hybrid bentonites enabled tracing changes in permeability, compressive strength and tensile strength in the transformation zone as well as compactability referred to the clay content in sand mixture. Selected technological and strength parameters of synthetic sands are crucial for the foundry, because they significantly affect the quality of the finished casting. Based on the analysis of the results, the optimal composition of hybrid bentonite was selected.
EN
The molasse’s vinasse, because it contains three groups of color processes in it, i.e., melanoidins, hexose alkaline degradation products, and sucrose caramelization products, is one of the most difficult to treat wastewater. Vinasse is toxic to various microorganisms, harmful to soil, groundwater, and vegetation. The aim of the study was using five natural sorbents: halloysite (PJC and KR), two types of zeolites differing in grain thickness and bentonite. The highest decolorization (74% and 62%) was obtained in the process with bentonite and halloysite PJC. Melanoidins and hexose alkaline degradation products were removed when KR and PJC were dosed. After decolorization, in almost all experiments COD and phosphate phosphorus contents were reduced. When bentonite was tested, the organic acids were removed.
PL
Wywar melasowy, ze względu na zawarte w nim trzy grupy związków barwnych tj. melanoidyn, produktów alkalicznego rozkładu inwertu oraz produktów karmelizacji sacharozy, jest jednym z najtrudniejszych do unieszkodliwienia ścieków. Wywar jest toksyczny dla wielu mikroorganizmów, szkodliwy dla gleby, wód podziemnych i roślinności, dlatego przed odprowadzeniem wywaru do środowiska naturalnego substancje barwne muszą zostać z niego usunięte. W pracy sprawdzono jak do usuwania związków barwnych z kukurydziano-melasowego wywaru gorzelniczego nadaje się pięć naturalnych sorbentów mineralnych: haloizyty PJC i KR, dwa zeolity różniące się grubością ziarna oraz bentonit. Najbardziej efektywne odbarwienie (na poziomie 74% i 62%) uzyskano w procesie z zastosowaniem bentonitu oraz haloizytu PJC. Melanoidyny i produkty alkalicznego rozkładu inwertu najskuteczniej zostały usunięte przy udziale bentonitu, natomiast karmele w obecności haloizytów KR oraz PJC. Po procesie dekoloryzacji prawie we wszystkich próbach zmalała zawartość ChZT oraz zawartość fosforu fosforanowego, natomiast wzrosła zawartość ogólnego węgla organicznego. Po procesie dekoloryzacji wywaru z wykorzystaniem bentonitu zmalała również zawartość poszczególnych kwasów.
PL
W artykule zaprezentowano wyniki badań laboratoryjnych oceny właściwości wiążących dwóch gatunków odlewniczych bentonitów wapniowych. Bentonity poddano chemicznej modyfikacji za pomocą węglanu sodu, w kilku przyjętych udziałach procentowych. Na wybranych próbkach oceniono takie parametry fizykochemiczne, jak: wytrzymałość na ściskanie, współczynnik pęcznienia, zawartość montmorylonitu. Uzyskane wyniki pozwoliły na wykreślenie tzw. krzywej aktywacji bentonitu. Dla wybranych próbek przeprowadzono badania parametrów fizykochemicznych w podwyższonej temperaturze. Całość badań zarówno stopnia aktywacji, jak i żaroodporności bentonitu pozwoliły na optymalny dobór udziału węglanu sodu biorącego udział w jego modyfikacji tak, aby uzyskać jak najlepsze parametry wiążące bentonitu odlewniczego.
EN
The paper presents laboratory test results for an assessment of the binding characteristics of two grades of calcium bentonite compounds for casting moulds. The bentonite compounds were chemically modified with sodium carbonate at several different percentage ratios of the modifier. Samples were selected as the specimens and assessed for certain physical and chemical characteristics, including compressive strength, swelling factor, and montmorillonite content. The test results allowed the so-called bentonite activation curves to be plotted. Some of the specimens had their physical and chemical characteristics tested at high temperatures. The entirety of the laboratory tests of bentonite activation and heat resistance enabled an optimised selection of the sodium carbonate percentage fraction for a bentonite compound modification which would produce the best binding properties of foundry bentonite.
13
Content available remote Wpływ dodatku bentonitu na właściwości uszczelniające popiołu lotnego
PL
W przypadku doboru materiału do budowy warstwy uszczelniającej niezbędne jest określenie jego współczynnika filtracji. Badania przewodności hydraulicznej przeprowadzono dla popiołu lotnego oraz popiołu lotnego z dodatkiem 5, 10 lub 15% bentonitu. Próbki badano w warunkach niemożliwej bocznej rozszerzalności przy użyciu konsolidometru typu Rowe’a-Bardena. Zaobserwowano wpływ dodatku bentonitu na zmniejszenie wartości przewodności hydraulicznej badanych mieszanin. Otrzymane z badań wartości współczynnika filtracji wskazują, że badane materiały mogą być stosowane do wbudowywania w warstwy uszczelniające składowisk odpadów.
EN
In process of choosing material to be built in sealing layer it is necessary to obtain its hydraulic conductivity. Laboratory tests of hydraulic conductivity were conducted on fly ash and fly ash with 5, 10 or 15% of bentonite addition. The samples were tested in the Rowe-Barden consolidometer. It was observed, that bentonite addition has influence on the decrease of the hydraulic conductivity of tested mixtures. The obtained results show that tested materials are accurate to be built in landfill sealing layers.
EN
In this work, an assessment and comparison of the quality of selected bentonites and bentonite mixtures was made. The samples consisted of available foundry materials used for bonding green sands. Determining the homogeneity degree and specific surface area of the grains allowed us to compare the examined materials and determine their influence on other parameters. On the basis of a thermal analysis of the bentonites or bentonite mixtures, the changes occurring in the sample during its heating were determined. Determining the potential for ion exchange and montmorillonite content enabled us to assess the binding properties of the materials. The preparation of six green sands with different bentonites or bentonite mixtures gave us the opportunity to assess the changes in apparent density, permeability, compressive strength and friability as a function of humidity, and the impact of different materials on the mentioned parameters. Their charts were analyzed, and the molding sand with the addition of bentonite or a bentonite mixture was selected for which these parameters are favorable. On this basis, the best-presented binding material was assessed and selected.
EN
The study of collapsible soils that are generally encountered in arid and semi-arid regions remains a major issue for geotechnical engineers. This experimental study, carried out on soils reconstituted in the laboratory, aims firstly to present a method of reducing the collapse potential to an acceptable level by treating them with different levels of bentonite–cement mixture while maintaining the water content and degree of compactness, thus reducing eventual risks for the structures implanted on these soils. Furthermore, a microscopic study using scanning electron microscopy was carried out to explore the microstructure of the soil in order to have an idea of the phenomena before and after treatment. The results show that treatment with a bentonite–cement mixture improves the geotechnical and mechanical characteristics, modifies the chemical composition of the soil, reduces the collapse potential and the consistency limits. The microstructural study and the X-ray energy dispersive spectroscopy analysis clearly illustrate an association of elementary particles in the soil aggregates, whereby the arrangement of these aggregates leads to the formation of a dense and stable material.
16
Content available remote Strukturotwórczy środek polimerowy do płuczek wodnodyspersyjnych
PL
Opisano badania nad zastąpieniem bentonitu w recepturach płuczek wiertniczych nowym środkiem polimerowym (o oznaczeniu CAGEx-v.2.). Głównym zadaniem badanego środka była budowa struktury oraz zapewnienie dobrych parametrów reologicznych płuczek wodnodyspersyjnych. Wyniki przeprowadzonych badań wykazały, że opracowany środek może być z powodzeniem zastosowany w praktyce przemysłowej.
EN
Bentonite was replaced in water-based mud formulas with a polymeric agent. The mud showed good rheol. properties, thermal stability and resistance against salts. The agent was recommended for industrial practice.
EN
The objective of the work was to investigate the possibility of application of carbon and bentonite nanoparticles in carboxylated acrylonitrile-butadiene rubber (XNBR) and the related effects of the nanofi llers on the structure, as well as mechanical and barrier properties, of the resulting composites. The composites were designed for use in protective clothing and gloves. XNBR compounds were modifi ed with 2 phr of graphene fl akes, graphene oxide, or modifi ed bentonite, and crosslinked with sulfur-accelerator system. Rubber compounds were prepared using a conventional method with a laboratory rolling mill. The composites were studied in terms of structure (WAXS), surface morphology (AFM), the presence of functional groups (ATR-FTIR) barrier properties against chemical substances (mineral oil) and swelling properties, as well as mechanical properties (abrasion resistance and tensile strength). The composites were characterized by very high resistance to oil permeation (breakthrough time >480 min). The type of nanofi ller added to the XNBR blend in the amount of 2 phr did not signifi cantly affect mechanical parameters.
PL
Zbadano wpływ zawartości modyfikowanych krzemianów oraz komercyjnych dodatków zmniejszających palność na właściwości użytkowe sztywnych pianek poliuretanowych (SPPUR), wytwarzanych metodą jednostopniową z dwuskładnikowego układu – przedmieszka poliolowa i izocyjanian oraz oznaczono ich właściwości fizyczne, mechaniczne i odporność na płomień. Strukturę wytworzonych pianek oceniano przy użyciu mikroskopu świetlnego (optycznego). Najmniejszą palność (klasa palności V-1, graniczny wskaźnik tlenowy LOI = 23,5 %) wykazywała pianka poliuretanowa zawierająca polifosforan amonu (APP), fosforan trietylu (TEP) oraz haloizyt modyfikowany żywicą melaminowo-formaldehydową (HALM). Próbki referencyjnej nie udało się sklasyfikować wg testu UL94, a odpowiadająca jej wartość LOI wynosiła jedynie 19,7 %.
EN
The effect of the amount of the modified silicates and commercial flame retardants on the properties of rigid polyurethane foams (SPPUR) was investigated. The foams were prepared in a one-step process from two-component system: polyol premix and isocyanate. The mechanical and physical properties as well as flame resistance of the prepared rigid foams were evaluated. The structure of foams was analyzed using optical microscope. It was found that the polyurethane foam containing ammonium polyphosphate (APP), triethyl phosphate (TEP) and halloysite modified with melamine-formaldehyde resin (HALM) had the lowest flammability (class V-1, LOI = 23.5 %) while the reference sample was not classified in the UL94 test (LOI = 19.7 %).
PL
Przedstawiono prace nad projektowaniem i budową urządzenia stabilizującego ciśnienie robocze zaczynu cementowego, który jest wykorzystywany w technologii Deep Soil Mixing (DSM)
EN
The article describes research carried out for design and construction of devices stabilizing the working pressure of cement slurry, with use of Deep Soil Mixing (DSM).
EN
Fluoride is regarded as one of the strongest oxidants, which causes oxidative changes in cells of living organisms. It may both increase the content of reactive oxygen species and inhibit the activity of antioxidative enzyme. In recent years, many researchers successfully used the properties of clay minerals in the sorption of fluoride ion from water. This raises the question of the possibility of limiting the effect of fluorine on the negative changes in plants by adding bentonite to soil. A two-year pot experiment was carried out in the Greenhouse of West Pomeranian University of Technology in Szczecin, on loamy sand and sandy loam. Each sample of soil was mixed with three different concentrations of bentonite – 1, 5, 10% of dry weight (DW) of the soil and then treated with 30 mmol of F- per 1 kg of dry weight of the soil in a form of NaF solution. A control series was prepared for each soil, to which no additives were added. The medium prepared in such way was transferred to plastic pots (3 kg each) and seeded with 16 pea seeds of Pisum sativum. In three phases of pea development (4 leaves unfolded, flowering and development of fruit), fresh leaf samples were collected and the concentrations of ascorbic acid, reduced glutathione, total flavonoids and total polyphenols were measured. Sodium fluoride introduced to the soil changed the level of antioxidant parameters in the plant, which may suggest that fluoride is involved in the formation of reactive oxygen species, resulting in oxidative stress. Bentonite in a dosage of 10% reduced the toxic effects of fluoride on the oxidative balance and morphological changes in the plant, which was observed especially for loamy sand, naturally poor in clay minerals.
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