Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 62

Liczba wyników na stronie
first rewind previous Strona / 4 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  jony metali
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 4 next fast forward last
EN
The saponite-containing product from the stage of process water clearing at benefication plant of the PAO Severalmaz was thickened using the electrochemical separation for use as sorbent of nickel and copper ions. The product features a high sorption capacity relatively the nickel and copper ions. It has been established that the sorption capacity can be enhanced by roasting the product at 750°С to 194 and 212 mg/g for the nickel and copper ions respectively. An organomineral sorbent for nickel ions based on copper-nickel ore tailings of the JSC „The Kolskaya Mining and Metallurgical Company”, thermally activated at 700ºС, has been synthesized. The surface modification was performed by using the non-covalent immobilization of dimethylglyoxime.
PL
Produkt zawierający saponit z etapu oczyszczania wody technologicznej w zakładzie wzbogacania PAO Severalmaz został zagęszczony przy użyciu rozdzielania elektrochemicznego w celu zastosowania jako sorbent jonów niklu i miedzi. Produkt cechuje się dużą pojemnością sorpcyjną, w stosunku do jonów niklu i miedzi. Ustalono, że pojemność sorpcyjna może być zwiększona przez prażenie produktu w temperaturze 750°C do 194 i 212 mg/g odpowiednio dla jonów niklu i miedzi. Zsyntetyzowano organo-mineralny sorbent dla jonów niklu oparty na odpadach z wzbogacania rud miedzi i niklu JSC „The Kolskaya Mining and Metalurgical Company”, aktywowany termicznie w 700ºС. Modyfikację powierzchni przeprowadzono stosując niekowalencyjną immobilizację dimetyloglioksymem.
EN
The removal of heavy metals from aqueous solutions using walnut shells was investigated. The effects of pH, contact time, initial metal concentration, adsorbent concentration, and co-ions were studied in synthetic solutions. Metal uptake was found to be dependent on the initial pH of the solution; the removal rate increased upon increasing pH, showing the highest affinity at pH 5–7. The amount of metal removed improved with increasing initial concentration. Increasing adsorbent dosage enhanced removal efficiency, but reduced the amount absorbed per unit mass of walnut shells. The presence of co-ions suppressed the uptake of heavy metals, divalent ions having a more negative effect than monovalentions. The adsorption of Zn, Cd and Ni onto walnut shells was found to fit Langmuir and Freundlich isotherms. The results obtained in the tests with mining waste leachate showed the potential use of walnut shells for the removal of heavy metals.
EN
This review article describes the results of a 15-year cooperation between the Department of RNA Biochemistry at the Institute of Bioorganic Chemistry, Polish Academy of Sciences in Poznań and the Medical Chemistry Team of the Faculty of Chemistry at the University of Wrocław, headed by Professor Małgorzata Jeżowska- -Bojczuk. A wide spectrum of antibiotics and other low molecular compounds and their complexes with Cu2+ ions have been tested as potential inhibitors of the HDV ribozyme catalytic reaction. Unexpectedly, it has been found that a number of compounds, depending on the conditions, exhibit inhibitory or stimulatory properties, i.e. they act as modulators of the RNA catalysis process. It was found that the effect of stimulation / inhibition of the catalytic activity of the HDV ribozyme is closely related to the degree of protonation of the antibiotics under study in given conditions. Their ability to inhibit catalysis also increases after binding the Cu2+ cation. In an environment with a higher pH, antibiotics usually stimulate the cleavage reaction, as at least some of their nitrogen centers are allowed to participate in the catalysis reaction, as proton acceptors / donors or a catalytic metal ion coordination site. During the study of one of the antibiotics, bacitracin, it was also observed that it exhibits nucleolytic properties with RNA and DNA molecules. The discovery of the hydrolytic properties of bacitracin extended the potential use of this antibiotic in antiviral therapy with the aim to destroy undesired nucleic acids in the cell. To search for DNAzymes catalyzing RNA hydrolysis, the in vitro selection method was used. In the selection experiment aimed at obtaining DNAzymes active in the presence of Cd2+ ions, variants belonging to the family of DNAzymes 8–17 previously described in the literature were obtained. Analysis of their properties showed that not only Cd2+ but also Zn2+ and Mn2+ ions support catalysis, therefore the site of catalytic metal ion coordination is not highly specific. The DNAzymes obtained in the second selection experiment showed an optimum of catalytic activity in the pH range of 4.0–4.5 and were inactive at a pH higher than 5.0. Interestingly, they do not require the presence of any divalent metal ions as cofactors in the catalysis reaction. The obtained results broaden the repertoire of DNAzymes which operate under non-physiological conditions and bring new information on the possible mechanisms of reactions catalyzed by nucleic acids.
EN
Many of biochemical paths and processes require some metal ions to occur. There are also known the negative effects of the presence of metal ions in the organism. The both sides of metal ions interactions on the living organism require specific regulations and cannot be left without supervision and control of the organism itself. One of the strategy to keep the control on metal ions are cystein-rich proteins that play crucial role in detoxication of metal ions that are dangerous for human organism as well as they help to maintain homeostasis of essential metal ions. Matallothioneins are one of the well known, but still not fully understood, cysteine- rich proteins. They are small proteins but may contain up to 30% of cysteine residues in the sequence, and what makes them very special from chemical point of view - all of the thiols present there are reduced [1]. This property makes these proteins very tempting for coordination of various metal ions. The most efficient binding to metallothionein is observed for the ions belonging to a Group 11 and 12. Cu+, Zn2+ and Cd2+ represent these metal ions [2]. Besides of the lack of disulfide bridges, metallothioneins show also the absence or low amount of aromatic amino acid residues in the sequence [1]. Studies of the metallothioneins and their isoforms among different organisms show that the position of cysteine residues is very conservative [3]. Considering this aspect of metallothionein structure, some specific motifs of cysteine residues arrangement can be found in the sequence of these proteins. Most of the common polythiol motifs are CXC, CXXC, CXXXC, CC – where C is a cysteine residue and X is random α-amino acid residue (other than cysteine) [3–5]. The influence of the cysteine residues organization on the specificity of metal ions binding was intensively studied. The differences observed for specificity of metal ions binding by metallothioneins and selected polythiol motifs are reviewed in this paper – with strong emphasis on the effect of the cysteine residues topography.
5
PL
Przedstawiono wyniki badań usuwania jonów Co2+ z roztworów wodnych za pomocą węgla aktywnego Norit SX2, zmielonych łusek ryżu oraz żywicy jonowymiennej C-160. Proces sorpcji opisano za pomocą modelu Langmuira. Największym powinowactwem do jonów Co2+ charakteryzował się jonit C-160. Wykazano, że łuska ryżowa i węgiel aktywny są skutecznymi sorbentami tylko w roztworach rozcieńczonych. Morfologię powierzchni sorbentów badano za pomocą skaningowego mikroskopu elektronowego.
EN
Activated C, com. ion exchange resin and shredded rice husks (grain size ≤ 150 μm) were used as sorbents (2 g to 200 mL of CoSO4·7H2O soln. with concns. 10-10 000 mg/L). The contact time of each sorbent with adsorbate soln. was 60 min. Concns. of Co2+ ions in adsorbate soln. were detd. using visible and near-ultraviolet light spectroscopy. The sorption was described by the Langmuir model. The tested materials were effective sorbents only in dild. solns., and a sorption capacity depended on the pH of the solns. In addn., the surface morphol. of the sorbents was examd. by scanning electron microscopy.
6
Content available remote Badanie transportu jonów metali w wybranych układach separacyjnych
PL
Przedstawiono ługowanie, ekstrakcję ciecz-ciecz i ultrafiltrację micelarną jako skuteczne sposoby wydzielania takich pożądanych jonów metali, jak platynowce i kobalt z odpadowych katalizatorów samochodowych i z roztworów wodnych.
EN
Pulverized spent automobile catalyst was leached with acidic solns. (optionally with H₂O₂). The leachates were liq.-liq. extd. with com. org. phase-contg. complexants to remove Fe(III), Mg(II) and Zn(II) ions and to sep. them from Pt group ions present in the raffinate. Co(II) ions were also recovered by using a com. complexant. The ultrafiltration in presence of surface active agents resulted in sepn. of Co(II) ions from Zn(II) ions.
PL
Biowęgiel jest materiałem, który zyskuje coraz większą uwagę jako opłacalny sorbent do oczyszczania roztworów wodnych z toksycznych dla środowiska jonów metali ciężkich (As, Cr, Pb, Cu, Zn i Cd). Brakuje jednak informacji na temat mechanizmów sorpcji dla różnych jonów metali. Niniejsze opracowanie prezentuje kluczowe czynniki oraz proponowane mechanizmy adsorpcji w celu wyjaśnienia zachowania adsorpcyjnego biowęgla. Artykuł podsumowuje charakterystyczne właściwości biowęgla (np. pole powierzchni, porowatość, pH, ładunek powierzchniowy, grupy funkcyjne i składniki mineralne) oraz główne mechanizmy regulujące sorpcję. Własności biowęgla różnią się znacznie między sobą w zależności od rodzaju materiału wsadowego oraz zastosowanej temperatury pirolizy. W wyższej temperaturze wytwarzany jest biowęgiel o większej powierzchni, porowatości, pH i zawartości minerałów, ale o mniejszej liczbie grup funkcyjnych. W niniejszej pracy zaprezentowano biowęgiel jako materiał wykazujący duży potencjał skutecznego zwalczania zanieczyszczeń ze środowiska wodnego, biorąc pod uwagę szeroką dostępność surowca, korzystne fizyczne i chemiczne właściwości powierzchni.
EN
The biochar is a material which gaining more attention as a effective sorbent for the purification toxic metals ions (As, Cr, Pb, Cu, Zn and Cd) from environmentally aqueous solutions. However, there is not so many information about sorption mechanisms of metals ions. In this paper presented factors and proposed mechanisms of adsorption to explain about behavior of adsorption by the biochar. The article summarized the characteristic of the biochar (eg. surface area, porosity, pH, surface charge, and functional groups minerals) and mechanism which that can be regulate sorption. Biochar has much different properties, which depending at the type of feed material and temperature of pyrolysis. In the higher temperatures we can produce biochar with larger surface area, porosity, pH and mineral content, but less functional groups. This paper present the biochar as a material which demonstrating a large potential for effective control by the pollution of aquatic environment, taking the wide availability of materials and favorable physical and chemical properties.
EN
The degradation of flutriafol in aqueous persulfate (S2O82–) system in the presence of selected transition metal ions was investigated. In the presence of Ag+ or Fe2+, flutriafol degradation occurs, whereas in the presence of Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Bi3+ ions, the degradation is less than 15%. The Ag+/ S2O82– aqueous system being the most effective was adopted for experimental and theoretical investigations. It was confirmed that pH of 3.0 is the most suitable, and that both · SO4–and ·OH– radicals are the main active species to afford flutriafol degradation, with the former contributes more than the latter. To elucidate degradation mechanism, molecular orbital calculations were performed and reaction intermediates identified by GC/MS and HPLC/MS/MS analyses. Three degradation pathways are proposed that involve the cleavage of C–N and C–C bonds as a result of ·SO4– attack, as well as the formation of hydroxylated products due to · OH radicals.
EN
His-tags are specific sequences containing six to nine subsequent histydyl residues and they are used commercially in immobilized metal affinity chromatography (IMAC) as molecular ‘anchors’ that bind to a metal ion (usually nickel), immobilized by chelation with nitrilotriacetic acid (NTA) bound to a solid support [37, 38]. Consecutive histidines are the common denominator for both His-tags used in molecular biology and for quite remote biological phenomena – more than 2000 histidine- rich proteins (HRPs) are found in microorganisms including 60% and 82% of archaeal and bacterial species, respectively and their roles are not well characterized [73]. The physicochemical properties of histidine make it a versatile amino acid that influences protein conformation and enzymatic activity [15]. Many natural proteins with a His-tag domain are assigned to different functions, for example: most bacterial proteins, containing this motif are probably involved in the homeostasis of nickel ions [68, 76], while others, e.g. newly isolated peptides from the venom of the snake genus Atheris contain poly-histidyl-poly-glycyl sequences (pHpG) can act on the cardiovascular system by inhibiting snake venom metalloproteinases and affect its function by acting on specific receptors [58, 62]. His-rich motifs have been found also e.g. in Zn2+ transporters, prion proteins, His-rich glycoproteins, transcription factors or numerous copper-binding proteins [56, 67, 84]. Binding mode and the thermodynamic properties of the system depends on the specific metal ion and the histidine sequence. Despite the wide application of the His-tag for purification of proteins, little is known about the properties of metalbinding to such tag domain. Recent experimental and theoretical studies have shown that metal ions, e.g. Cu2+ can bind to various sets of imidazoles depending on the number of histidine residues that are located in His-rich sequences. The occurrence of polymorphic binding states and the formation of an α-helical structure induced by metal ion coordination suggest that proteins with a His-tag domain may serve as the dynamic site able to ‘move’ metal ions along the tag sequence [99, 100]. This might explain the frequent occurrence of such sequences in bacterial Ni2+ chaperones, which transfer the metal ion between different proteins.
10
EN
This paper examines the accumulation of metal ions from soil in selected edible plants belonging to the Brassicaceae and Lamiaceae families. The effect of metal ions on factors, such as growth and morphology are also investigated. The results indicate that the addition of selected metal ions to the soil significantly increases the concentration of metal ions in the plants. The application of zinc ions significantly enhances Zn uptake in Ocimum basilicum and Mentha piperita (Lamiaceae family). Nickel ions significantly increase Ni accumulation in Lepidium sativum (Brassiaceae family). The research shows that nickel, zinc and copper accumulate in leaves at different concentrations depending on the plant species.
EN
Chitosan is a natural product derived from chitin, which is mostly found in exo-skeletons of shrimp, crab and lobster shells. This paper presents a short review of the literature regarding the use of chitosan and its modifications for removing selected pollutants from water and wastewater. In particular, the examples of removal of metal ions, dyes, anions and phenols were described. Furthermore, the possibility of the use of chitosan as a coagulant and flocculant in water and wastewater technologies are also shown. Based on the literature review described in this article it can be concluded that chitosan and especially its modifications is a very promising sorbent for removing a broad spectrum of pollutants from aqueous solutions. It also presents directions for further research in order to obtain a better knowledge of the practical applications of chitosan.
PL
Chitozan jest naturalnym produktem pochodzącym z chityny, która najczęściej występuje w egzo-szkieletach krewetek i krabów oraz w muszlach homarów. W publikacji dokonano krótkiego przeglądu literatury odnośnie zastosowań chitozanu i jego modyfikacji do usuwania wybranych zanieczyszczeń z wody i ścieków. W szczególności, opisano przykłady usuwania jonów metali, barwników, anionów i fenoli. Przedstawiono również możliwości zastosowania chitozanu jako koagulantu i flokulantu w technologii wody i ścieków. Na podstawie przeglądu literatury opisanego w tym artykule, można stwierdzić, że chitozan a zwłaszcza jego modyfikacje, jest bardzo obiecującym sorbentem do usuwania szerokiego spektrum zanieczyszczeń z roztworów wodnych. Przedstawiono również kierunki dalszych badań w celu uzyskania lepszej wiedzy dotyczącej praktycznych zastosowań chitozanu.
EN
Salvinia natans L. is a known bioaccumulator of metal ions from the aquatic environment. Exposure of plants to prolonged impact of toxins along with a large dose of the metal affects the physiological condition of the plants. The changes occurring in the plants in the phytoremediation process in contaminated medium culture of 5, 10, 15 and 20 mg Cu/dm3 show two basic physiological parameters: the assimilation pigment content (chlorophyll a and b) responsible for the production of energy in the process of photosynthesis, and the total protein level as the main constituent of the plant. Conducted studies confirmed a negative effect of high concentrations of copper(II) on Salvinia natans L. plants which in these conditions are capable to bioaccumulate metal from each contaminated culture medium.
PL
Endoprotezoplastyka krążka międzykręgowego jest stosunkowo nową procedurą leczenia chorych z przewlekłymi bólami kręgosłupa o charakterze dyskogennym. Niezależnie od doboru materiałów, z których wykonuje się elementy składowe implantu krążka międzykręgowego, wciąż najistotniejszym czynnikiem ograniczającym czas jego użytkowania jest podatność na zużycie wskutek tarcia. W artykule przedstawiono ocenę procesów fizykomechanicznych występujących podczas użytkowaniu implantów, ze szczególnym uwzględnieniem procesów tribologicznych. Uzyskane wyniki wskazują, że za względnie korzystny zestaw materiałów należy uznać parę trącą typu metal–polietylen. Zastosowanie polimerowej wkładki pozwala na uzyskanie stosunkowo niskich oporów tarcia (współczynnik tarcia poniżej 0,1), nawet przy dużym obciążeniu układu (2500źN). W przypadku pary trącej typu metal–metal za najkorzystniejszy materiał należy uznać stop Co28Cr6Mo. W ramach artykuł dokonano oceny mechanizmu zużycia poszczególnych par trących. Przedmiot analiz w przypadku pary trącej typu metal–metal stanowiła także analiza rozkładu wielkości produktów zużycia i stężenie jonów pierwiastków stopowych w cieczy smarującej.
EN
Total disc replacement is a relatively new treatment procedure of patients with chronic back pain. Regardless of the choice of materials from which the disc components are made, the most important factor limiting their service life is susceptibility to wear due to friction. This paper presents an assessment of physico-mechanical processes occurring during the use of implants, with particular emphasis on tribological processes. The results obtained during tribological tests show that the relatively favourable combination of materials is metal-polyethylene articulation. The use of a polymeric insert allows for a relatively low friction resistance (friction coefficient less than 0.1) even for a large load (2500 N). In metal-metal articulation the most favourable material is Co28Cr6Mo alloy. In the frame of this article, the mechanisms of wear for both articulation types were assessed. For metal-on-metal friction pair, wear debris size distribution, as well as metal ion concentration analysis were made.
PL
Przedstawiono wyniki badań nad otrzymywaniem kwasów huminowych z polskich węgli brunatnych z kopalń Bełchatów i Konin. Preparatyka kwasów huminowych polegała na doborze stężenia ługu sodowego, czasu i temperatury ekstrakcji oraz stosunku ilości ługu do ilości węgla. Jako optymalne wybrano następujące parametry: 5-proc. ług sodowy, temperatura ekstrakcji 100°C, czas ekstrakcji 1 h, stosunek ilości ługu sodowego do ilości węgla jak 20:1. Otrzymano 3 rodzaje preparatów huminowych: płynne, żele i stałe.
EN
Two Polish lignites (grain size 0.2-1.0 mm) were extd. with aq. soln. of NaOH (1-5% by mass) at 20-100°C for 1-24 h (lignite:NaOH mass ratio 1:40 to 1:5) to sep. the humic acids as Na huminates, pptd. with HCi, demineralized with aq. HCI at 100°C and dried at 80°C. Under the optimum conditions (concn. of NaOH soln. 5% by mass, extn. temp. 100°C, extn. time 1 h, lignite.NaOH ratio 1:20), the yield of humic acids was 69.1-70.9% by mass and ash content or 6.6% by mass. The products were considered as adsorbents.
EN
Adsorption isotherms and kinetics of the removal of heavy metal ions (Ni, Pb, Zn) from aqueous solutions by natural adsorbents (zeolite, bentonite, clay) were investigated in a lab-scale batch study. The effect of various parameters such as adsorbent dosage, initial concentration of heavy metal ions, temperature, and agitation time were studied to optimise the conditions. Under those optimized conditions (180 rpm agitation rate, 120 min agitation time, pH 4.0, 298 K, 100 mg/dm3 initial adsorbate concentration), the removal percentages of heavy metal ions for natural adsorbents have been determined. The adsorption mechanisms and characteristic parameters of the process were analyzed by two and three parameter isotherm models (Langmuir, Freundlich, Temkin, Redlich-Peterson, Toth and Sips), and kinetic models (Lagergren's pseudo-first order, Ho and McKay's pseudo-second order). Adsorption thermodynamics of heavy metal ions (changes of standard enthalpy, entropy and free energy) on zeolite, bentonite and clay were also studied at 298,318 and 338 K.
17
Content available remote Fosfoniowe ciecze jonowe jako przenośniki jonów metali
PL
Trzy fosfoniowe ciecze jonowe: chlorek i bis(2,4,4-trimetylopentylo)fosfinian triheksylo(tetradecylo)fosfoniowy oraz chlorek tributylo(tetradecylo)fosfoniowy zastosowano jako przenośniki Zn(II) w polimerowych membranach inkluzyjnych. Transport Zn(II) zależy od masowego stosunku IL/plastyfikator w membranie, rodzaju matrycy membrany, hydrofobowości powierzchni membrany, a także obecności jonów żelaza w fazie zasilającej.
EN
Three com. phosphonium ionic liqs. (trihexyl(tetradecyl)phosphonium chloride and bis(2,4,4-trimethylpentyl)phosphinate and tributyl(tetradecyl)phosphonium chloride) were used as Zn(II) carriers in o-NO2C6H4OC8H17-plastified poly(vinyl chloride) or cellulose triacetate-based inclusion membranes. Zn(II) transport depended on ionic liq./plasticizer ratio in the membrane, type of polymer, hydrophobicity of the membrane surface and presence of Fe ions in the feed phase.
18
Content available remote Eliminacja jonów uranylowych z roztworów wodnych metodą biosorpcji
PL
Dokonano przeglądu badań nad biosorpcją U(VI) z roztworów wodnych na różnego rodzaju mikroorganizmach. Zwrócono szczególną uwagę na bakterie, grzyby, drożdże i algi morskie jako efektywne biomateriały. Analizowano parametry wpływające na proces biosorpcji.
EN
A review, with 39 refs., of bacteria, fungi, yeast and seaweed used as an effective biomaterials for the biosorption  of U(VI) ions.
PL
Zbadano wpływ pH surówki flotacyjnej, stężenia kolektora i prędkości przepływu powietrza na przebieg flotacji jonowej i precypitacyjnej mieszaniny Al(III), Cu(II) i Zn(lI). Najwyższe wartości stałych szybkości flotacji badanych metali uzyskano dla procesów prowadzonych dla pH około 8, tj. w warunkach flotacji precypitacyjnej. Wykazano, że stałe szybkości flotacji badanych metali są proporcjonalne do prędkości przepływu powietrza flotującego w potędze około 0,8.
EN
Influence of the initial solution pH, collector concentration and air velocity on the course of Al(III), Cu(II) and Zn(II) ion and precipitate flotation was investigated. The highest values of flotation rate constants for aluminum, copper and zinc were observed for the precipitate flotation when a value of the initial solution pH was about 8. It was concluded that flotation rate constants for investigated metals were proportional to air velocity in the power of about 0.8.
EN
The study deals with the removal of residual contaminants Cu(II), Cd(II) and Pb(II) from soil using surfactants sodium dodecyl sulfate (SDS), sodium dioctyl sulfosuccinate, and Triton x-100. Surfactants were used with and without chelating agent ethylenediaminetetraacetic acid (EDTA). SDS (10 mM) was the most effective surfactant for removing metals. Replacing distilled water with SDS enhanced metal removal by the factor of 5.5, 28.8, and 29.1 for Cu(II), Cd(II), and Pb(II), respectively. SDS with EDTA was efficient in removing metals. Interaction of metal ions with respect to adsorption and desorption were also studied.
first rewind previous Strona / 4 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.