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Tytuł:
Equilibrium and kinetic studies on the removal of heavy metal ions with natural low-cost adsorbents
Autorzy:
Varank, G.
Demir, A.
Bilgili, M. S.
Top, S.
Sekman, E.
Yazici, S.
Erkan, H. S.
Powiązania:
https://bibliotekanauki.pl/articles/207257.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
adsorbents
adsorption
bentonite
dyes
heavy metals
kinetics
metal ions
water treatment
heavy metal removal
heavy metal ions
heavy metals ions removal
adsorbenty
adsorpcja
bentonit
barwniki
metale ciężkie
kinetyka
jony metali
usuwanie jonów metali ciężkich
uzdatnianie wody
Opis:
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.
Źródło:
Environment Protection Engineering; 2014, 40, 3; 43-61
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metalotioneiny i motywy policysteinylowe : oddziaływanie z jonami metali
Metallothioneins and polythiol motifs : interactions with metal ions
Autorzy:
Krzywoszyńska, K.
Kozłowski, H.
Powiązania:
https://bibliotekanauki.pl/articles/171939.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
metalotioneiny
motywy policysteinylowe
jony metali
metallothioneins
polythiol motifs
metal ions
Opis:
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.
Źródło:
Wiadomości Chemiczne; 2018, 72, 7-8; 383-395
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regulacja aktywności katalitycznej rybozymów HDV oraz deoksyrybozymów za pomocą antybiotyków i jonów metali
Regulation of the catalytic activity of HDV ribozymes and deoxyribozymes with antibiotics and metal ions
Autorzy:
Wrzesinski, J.
Ciesiołka, J.
Powiązania:
https://bibliotekanauki.pl/articles/171740.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
antybiotyki
rybozymy HDV
deoksyrybozymy
jony metali
antibiotics
HDV ribozymes
deoxyribozymes
metal ions
Opis:
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.
Źródło:
Wiadomości Chemiczne; 2018, 72, 7-8; 397-415
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polihistydylowe sekwencje z motywem His-tag – ich rola i biologiczne znaczenie oddziaływania z jonami metali
Polyhistidine sequences with His-tag motif – their role and biological significance of interaction with metal ions
Autorzy:
Wątły, J.
Kozłowski, H.
Powiązania:
https://bibliotekanauki.pl/articles/172145.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
histydyna
His-tag
jony metali
białka
histidine
His-tag motif
metal ions
proteins
Opis:
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.
Źródło:
Wiadomości Chemiczne; 2016, 70, 11-12; 1-24
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of the physiological condition of Salvinia natans L. exposed to copper (II) ions
Autorzy:
Hołtra, A.
Zamorska-Wojdyła, D.
Powiązania:
https://bibliotekanauki.pl/articles/207308.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Salvinia natans
bioremediation
copper
metal ions
metals
aquatic environments
culture medium
physiological condition
physiological parameters
phytoremediation
salwinia pływająca
bioremediacja
miedź
jony metali
fizjologia
środowisko wodne
pożywka hodowlana
stan fizjologiczny
parametry fizjologiczne
fitoremediacja
Opis:
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.
Źródło:
Environment Protection Engineering; 2015, 41, 3; 147-158
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kompleksy jonów metali d- i f-elektronowych z N-tlenkiem pirydyny i związkami pochodnymi : badania spektroskopowe
Complexes of d- and f-metal ions with pyridine N-oxide and its derivatives: spectroscopic studies
Autorzy:
Hnatejko, Z.
Powiązania:
https://bibliotekanauki.pl/articles/171812.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kompleksy jonów metali
jony metali
N-tlenki pirydyny
spektroskopia
complexes
metal ions
pyridine N-oxides
spectroscopy
Opis:
This article reviews results of studies, collected in the literature, related to complexation abilities of pyridine N-oxides, including forms and properties of dand f-metal ion complexes with this group of ligands. In this paper the synthetic pathways of the ligands, based on an oxidation of the corresponding heterocyclic compounds are presented (Scheme 3) [2, 4, 5]. Substituted pyridine N-oxides form an interesting group of compounds, which have found numerous applications [296-299, 314-318]. They have been used in catalysis, crystal engineering, synthesis of coordination polymers, as well as drugs and components in pharmaceutical chemistry [300-309]. Some of them are useful in destroying of microorganisms and the HIV virus [277, 278, 303-307]. Moreover, they are important compounds in the thermal and photochemical oxidation processes [296-299]. The complexes of metal ions with the N-oxide ligands can be formed by binding an oxygen atom of the N›O group, and/or by binding the substituents present in the aromatic ring, e.g. oxygen atoms of carboxylic groups. The complexes can be obtained in monomeric [64, 159], dimeric [58] or polymeric forms [60, 153, 175]. The formation of polymeric forms is more effective when the distance between the positions of COOH and N›O groups in the aromatic ring increases [168]. Complexes of Ln3+ ions and particularly of Eu3+ with pyridine N-oxides are good luminescent materials, better than their heterocyclic counterparts [180, 211]. The emission intensity of europium ions in these systems depends on the efficiency of the LMCT (ligand-metal charge transfer) and LMET (ligand-metal energy transfer) transitions, as well as on electron-donor properties of the substituents present in the pyridine N-oxide ring [37, 132, 155]. A special role in the complexation of Ln3+ ions plays cryptands, which can encapsulate the metal ion. This process protects the metal ion from a penetration of its first coordination sphere by solvent molecules or counterions [245, 246]. The complexes of europium(III) with macromonocyclic, macrobicyclic and acyclic ligands, equipped with photoactive units such as pyridine N-oxide, 2,2'-bipyridine-N,N'-dioxide or 3,3'-biisoquinoline-2,2'-dioxide in solutions, solid states, and incorporated in a silicate matrices by sol-gel method, gained a lot of attention [247-274].
Źródło:
Wiadomości Chemiczne; 2011, 65, 5-6; 461-501
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania aktywności dioksygenaz katecholowych w obecności jonów wybranych metali ciężkich w aspekcie bioremediacji środowisk zanieczyszczonych związkami aromatycznymi
Presence of some heavy metal ions: Bioremediation of an environment polluted with aromatic compounds
Autorzy:
Guzik, U.
Wojcieszyńska, D.
Greń, I.
Hupert-Kocurek, K.
Powiązania:
https://bibliotekanauki.pl/articles/236664.pdf
Data publikacji:
2010
Wydawca:
Polskie Zrzeszenie Inżynierów i Techników Sanitarnych
Tematy:
biodegradacja
bioremediacja
Stenotrophomonas
Pseudomonas
jony metali
biodegradation
bioremediation
Stenotrophomonas maltophilia KB2
Pseudomonas putida N6
metal ions
Opis:
Szczepy bakterii Stenotrophomonas maltophilia KB2 oraz Pseudomonas putida N6 odznaczają się zwiększoną zdolnością do degradacji związków aromatycznych. W badaniach stwierdzono całkowity rozkład fenolu (3 mmol/dm3) w ciągu pięciu godzin przez oba badane szczepy. U szczepu KB2 po indukcji fenolem wykazano obecność 2,3-dio-ksygenazy katecholowej odpowiedzialnej za meta-rozszczepienie związków aromatycznych, natomiast u szczepu Pseudomonas putida N6 wykazano obecność 1,2-dioksygenazy katecholowej, charakterystycznej dla szlaku orto rozszczepienia pierścienia aromatycznego. W wyniku badań nad wrażliwością tych enzymów na obecność jonów metali wykazano, że jony Zn2+ aktywowały 2,3-dioksygenazę katecholową szczepu KB2. Wszystkie pozostałe jony były inhibitorami tego enzymu. Spośród przebadanych jonów metali najsilniejszym inhibitorem obu wyizolowanych dioksygenaz okazał się jon Cu2+, natomiast w mniejszym stopniu aktywność 1,2-dioksygenazy katecholowej szczepu N6 hamowały Cd2+ i Zn2+. Wzrost aktywności tego enzymu zaobserwowano w obecności Co2+. Pozostałe jony metali nie wpłynęły znacząco na aktywność 1,2-dioksygenazy katecholowej szczepu N6. Stwierdzona w badaniach częściowa aktywność obu badanych dioksygenaz po zastosowaniu soli metali sugeruje możliwość wykorzystania szczepów bakterii Stenotrophomonas maltophilia KB2 oraz Pseudomonas putida N6 do oczyszczania środowisk skażonych związkami aromatycznymi.
The strains of Stenotrophomonas maltophilia KB2 and Pseudomonas putida N6 are characterized by an enhanced capacity for degrading aromatic compounds: within five hours of incubation both the strains were found to provide a complete degradation of phenol (3 mmol/dm3). Upon induction with phenol, catechol 2,3-dioxygenase, an enzyme responsible for the meta-cleavage of aromatic compounds, was detected in the Stenotrophomonas maltophilia KB2 strain, whereas in the Pseudomonas putida N6 strain the presence was revealed of catechol 1,2-dioxygenase, an enzyme characteristic of the pathway for the orthofission of the aromatic ring. Tests on the sensitivity of the enzymes to metal ions have demonstrated that Zn2+ ions activated catechol 2,3-dioxygenase in the KB2 strain. The other metal ions were found to be inhibitors of this enzyme. Among the metal ions tested, the Cu2+ ion was the strongest inhibitor of the two isolated dioxynases. Slightly weaker was the inhibition of catechol 1,2-dioxygenase induced by Cd2+ and Zn2+ ions in the N6 strain. The activity of this enzyme increased in the presence of Co2+ ions. The other ions had no significant influence on the activity of the catechol 1,2-dioxygenase isolated from the N6 strain. The partial activity of both dioxygenases observed upon the application of metal salts suggests that both the strains, Stenotrophomonas maltophilia KB2 and Pseudomonas putida N6, may contribute much to the remediation of an environment polluted with aromatic compounds.
Źródło:
Ochrona Środowiska; 2010, 32, 1; 9-13
1230-6169
Pojawia się w:
Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal of zinc, cadmium and nickel from mining waste leachate using walnut shells
Autorzy:
Ayala, Julia
Fernandez, Begona
Powiązania:
https://bibliotekanauki.pl/articles/208277.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
metal ions
adsorption
biosorption
adsorbent
kinetics
copper
jony metali
adsorpcja
biosorpcja
kinetyka
miedź
Opis:
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.
Źródło:
Environment Protection Engineering; 2019, 45, 2; 141-158
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium
Autorzy:
Souza, E. J.
Cristante, V. M.
Padilha, P. M.
Jorge, S. M. A.
Martines, M. A. U.
Silva, R. I. V.
Carmo, D. R.
Castro, G. R.
Powiązania:
https://bibliotekanauki.pl/articles/779827.pdf
Data publikacji:
2011
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
2,2-bipirydyna
żel krzemionkowy
adsorpcja
jony metali
2,2'-bipyridine
silica gel
adsorption
metal ions
Opis:
A method was developed to attach 2,2-bipyridine (BP) onto a silica gel surface by a two-step reaction. The fi rst step consisted of a reaction between the matrix and a silylating agent, 3-chloropropyltrimethoxysilane. In the second step of the reaction, a ligand molecule was attached onto Si-CPTS, yielding the product Si-BP. The modified material contained 0.431±0.01 mmol of 2,2-bipyridine per gram of modified silica, as confirmed by FT-IR spectra of the proposed structure. The surface modification was characterized by the BET technique, which revealed a decrease in the surface area from 614 to 450 m2 g-1. The series of adsorption isotherms for the metal ions were adjusted to fit a modified Langmuir equation. The maximum number of moles of copper, cadmium and lead ions adsorbed was 0.64, 0.53, and 0.54 mmol g-1, respectively. The surface saturation was calculated as ¢ fraction and the values obtained, Cu(II) =1.160, Cd(II) = 1.044 and Pb(II) = 0.997, suggest a type 1:1 metal-ligand complex.
Źródło:
Polish Journal of Chemical Technology; 2011, 13, 4; 28-33
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Właściwości koordynacyjne wybranych cyklicznych hormonów peptydowych oraz ich pochodnych
Coordination properties of selected cyclic peptide hormones and their analogues
Autorzy:
Witak, Weronika
Marciniak, Aleksandra
Powiązania:
https://bibliotekanauki.pl/articles/1409943.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
hormony peptydowe
peptydy
wiązanie disulfidowe
jony metali
peptide hormones
cyclic peptides
disulfide bridge
metal ions
Opis:
Hormones are a heterogeneous, significant compounds, responsible for proper functioning of living organisms, produced by specialized cells, tissues and glands. Theirs main role is signals transmission to target tissues, responsible for the right working of the whole organism. Dysfunctions of the hormones homeostasis balance lead to disease states [1-3]. Recently, scientists have paid attention to role of the metal ions in the proper synthesis of these compounds and functioning of human body [4]. More and more scientific works explain the complicated roles of metals as beneficial factors that stimulate the conformation of peptides. Metal ions are responsible for biological properties and influence of hormones binding to appropriate receptors, but also adverse factors [4,5]. The search for an answer to the question about the metal - hormone relationship has led to the development of a new, interdisciplinary studies: metalloendocrinology, linking inorganic chemistry with endocrinology [4]. In this work, we present the literature data that relate to metal - peptide hormone interactions. We focused on cyclic hormones with a disulfide bridge and their analogues. In our review we have focused on selected natural cyclic peptide hormones: oxytocin, vasopressin, somatostatin, hepcidin and amylin. The studies on the coordination abilities showed that transition metal ions, such as copper(II), zinc(II) or nickel(II), form stable complexes with described peptides. Metal ions actively participate in many phenomena. They have played role in the formation of amylin aggregates in patients with type 2 diabetes [6]. The high ability to copper(II) by hepcidin may have an effect on its homeostasis [7]. Stable complexes of oxytocin and vasopressin facilitate binding with appropriate receptors for these peptides [8].
Źródło:
Wiadomości Chemiczne; 2021, 75, 5-6; 799-821
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanizm sorpcji jonów metali w hydrożelu chitozanowym - badania kalorymetryczne
Mechanism of metal ion soprtion in chitosan hydrogel - calorimetric studies
Autorzy:
Zarzycki, R.
Modrzejewska, Z.
Kierzkowska-Pawlak, H.
Sujka, W.
Powiązania:
https://bibliotekanauki.pl/articles/127430.pdf
Data publikacji:
2009
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
chitozan
adsorpcja
jony metali
ciepło reakcji
chitosan
adsorption
metal ions
heat reaction
Opis:
Przedstawiono kalorymetryczne badania hydrożelu chitozanowego dotyczące mechanizmu sorpcji Cu(II), Ag(I) i Ca(II). Wyznaczono ciepła reakcji sorpcji tych jonów. Proces ten prowadzono dla maksymalnego stężenia danego jonu. Z pomiarów efektu cieplnego wynika, iż dla jonów Cu(II) i Ag(I) proces sorpcji ma charakter chemiczny (chemisorpcja). Efekt cieplny jest rzędu kilkudziesięciu kJ/mol. Natomiast jony Ca(II), które korzystnie wpływają na organizm ludzki, nie wykazują tego efektu.
In the present research, studies were performed to determine the character of adsorption of Ca(II), Cu(II), Ag(I) ions in chitosan. The studies were carried out for chitosan hydrogel. The character of sorption was determined on the basis of calorimetric studies. The heat of reaction was measured during the sorption of individual ions. The process of adsorption was carried out for a maximum ion concentration. It follows from the measurement of the heat of sorption for Cu(II) and Ag(I) ions that the sorption process has a chemical character, which is shown by a measurable thermal effect of the order of dozens kJ/mol. It is interesting that Ca(II) ions which have an advantageous influence on living organisms, do not reveal this effect.
Źródło:
Proceedings of ECOpole; 2009, 3, 1; 221-227
1898-617X
2084-4557
Pojawia się w:
Proceedings of ECOpole
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tribologiczne aspekty doboru materiałów na implanty krążka międzykręgowego kręgosłupa
Tribological aspects of material selection for intevertebral disc implant
Autorzy:
Gierzyńska-Dolna, M.
Lijewski, M.
Mróz, A.
Powiązania:
https://bibliotekanauki.pl/articles/189870.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
implant krążka międzykręgowego
współczynnik tarcia
zużycie
produkty zużycia
jony metali
intervertebral disc implant
friction coefficient
wear
wear debris
metal ions
Opis:
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.
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.
Źródło:
Tribologia; 2014, 3; 59-69
0208-7774
Pojawia się w:
Tribologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Możliwości sorpcyjne biowęgla w usuwaniu zanieczyszczeń ze środowiska wodnego
The sorption possibilities of the biochar as a decontaminating agent from aquatic environment
Autorzy:
Ślęzak, Ewelina
Poluszyńska, Joanna
Powiązania:
https://bibliotekanauki.pl/articles/392189.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Ceramiki i Materiałów Budowlanych
Tematy:
biowęgiel
sorpcja
jony metali
toksyna
środowisko wodne
ochrona środowiska
biochar
sorption
metal ions
toxins
water environment
environmental protection
Opis:
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.
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.
Źródło:
Prace Instytutu Ceramiki i Materiałów Budowlanych; 2018, R. 11, nr 33, 33; 62-72
1899-3230
Pojawia się w:
Prace Instytutu Ceramiki i Materiałów Budowlanych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rola metali w rozwoju choroby Alzheimera i Parkinsona
The role of metals in development Alzheimer's and Parkinson's diseases
Autorzy:
Żygowska, Justyna
Szymańska, Aneta
Powiązania:
https://bibliotekanauki.pl/articles/2057913.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
choroba neurodegeneracyjna
jony metali
β-amyloid
białka amyloidogenne
choroba Alzheimera
choroba Parkinsona
neurodegenerative diseases
amyloidogenic proteins
amyloid β
metal ions
Alzheimer's disease
Parkinson disease
Opis:
Neurodegenerative diseases are the consequence of progressive brain degeneration caused by the death of nerve cells. Many factors that influence the neurodegeneration development are still not fully known. A lot of studies indicate the contribution of metal ions in this process. Copper, zinc, and iron are trace elements essential for proper functioning of the body. They are part of many enzymes participating in the transmission of the nerve signals, electrons transport, neurotransmitters and nucleic acids synthesis, and oxygen storage. Disorder of metals homeostasis leads to the development of severe diseases and nervous system degenerations. An excess of copper and iron ions causes a significant increase in cellular oxidative stress. Metals catalyze the reactions of free radicals formation that destroy proteins, lipids, and nucleic acids. High concentration of copper and iron ions were found in the deposits of amyloidogenic proteins. Amyloid β (Alzheimer disease) and α synuclein (Parkinson disease) have ions binding chain structures. The metal-protein interaction increases oligomerization speed in vitro. A lot of evidence suggests that the disorder of Cu, Zn and Fe homeostasis accelerates the progress of brain neurodegeneration. Human organism contains many metals, which are not needed for the proper functioning of the body, e.g. aluminum. Al binds to nucleic acids causing an increase in cellular oxidative stress and initiating proteins oligomerization. The presence of aluminum is also considered to be disadvantageous for the nervous system. The lack of medicines for neurodegenerative diseases forces us to search for new therapies. The development of degenerations could be slowed down by chelators of toxic metals, but first, these diseases must be better understood. Adverse effects of high concentration of metal ions on brain functioning are not fully known. This knowledge is necessary to find effective drugs.
Źródło:
Wiadomości Chemiczne; 2022, 76, 1-2; 1-25
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surfactant assisted removal of Cu(II), Cd(II) and Pb(II) from contaminated soils
Autorzy:
Ramamurthy, A.
Schalchian, H.
Powiązania:
https://bibliotekanauki.pl/articles/207738.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
metal ions
soil pollution
surface active agents
contaminated soils
metal removal
residual contaminants
contaminants removal
surfactants
jony metali
zanieczyszczenie gleby
środki powierzchniowo-czynne
gleba zanieczyszczona
usuwanie metali
zanieczyszczenia resztkowe
usuwanie zanieczyszczeń
Opis:
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.
Źródło:
Environment Protection Engineering; 2013, 39, 3; 87-99
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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