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Tytuł:
Chromium Ions Removal by Capacitive Deionization Process: Optimization of the Operating Parameters with Response Surface Methodology
Autorzy:
Issa, Zainab M.
Salman, Rasha H.
Powiązania:
https://bibliotekanauki.pl/articles/2202352.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
capacitive deionization
electrosorption
carbon fibre
chromium
wastewater
Opis:
An innovative desalination method called electrosorption or capacitive deionization (CDI) has significant benefits for wastewater treatment. This process is performed by using a carbon fiber electrode as a working electrode to remove hexavalent chromium ions from an aqueous solution. The pH, NaCl concentration, and cell voltage were optimized using the Box-Behnken experimental design (BDD) in response surface methodology (RSM) to study the effects and interactions of selected variables. To attain the relationship between the process variables and chromium removal, the experimental data were subjected to an analysis of variance and fitted with a quadratic model. The optimum conditions to remove Cr(VI) ions were: pH of 2, a cell voltage of 4.3V, and NaCl concentration of 1.4 g/L. This study demonstrated that the carbon fiber electrode was very efficient in Cr(VI) ions removal and the BBD methodology was a practical and effective strategy for predicting the results of various experimental conditions during a CDI process for the removal of chromium ions.
Źródło:
Journal of Ecological Engineering; 2023, 24, 1; 51--65
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chromium-rich illite/smectite in the basal Balinka Conglomerate of the Upper Carboniferous-Permian Boskovice Basin (Bohemian Massif). Annales Societatis Geologorum Poloniae
Autorzy:
Hršelová, Pavla
Houzar, Stanislav
Buriánek, David
Všianský, Dalibor
Szczerba, Marek
Ciesielska, Zuzanna
Štelcl, Jindřich
Nehyba, Slavomír
Powiązania:
https://bibliotekanauki.pl/articles/24201051.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Chromium illite-smectite
Cr-rich spinelides
Balinka Conglomerate
diagenetic alteration
Upper Carboniferous
Boskovice Basin
Bohemian Massif
Opis:
The Upper Carboniferous polymictic Balinka Conglomerate was deposited along the western margin of the Boskovice Basin (eastern part of the Bohemian Massif). Angular aggregates of deep-green chromium-rich interstratified clay mineral R1-illite(0.8)/smectite (I/S) are present exclusively in the basal part of this unit. The textural position of chromium-bearing I/S (0.77–2.88 wt.% Cr2O3; 0.040–0.153 apfu Cr) in the conglomerate matrix indicates a genetic link with the highly altered chromium spinel, which is preserved in the relics. The source of Cr-rich spinelides was serpentinized peridotites in the adjacent Moldanubicum (Gföhl Unit). The formation of I/S is related to diagenetic processes in the conglomerate matrix. The fluids would have relatively high fugacity of CO2 and activity of K+. K/Ar ages of 284.1 ± 7.7 and 276.3 ± 7.4 Ma (lower Permian – Kungurian/Artinskian age) confirmed the diagenetic origin of this I/S.
Źródło:
Annales Societatis Geologorum Poloniae; 2023, 93, 2; 195--210
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Designing of X46Cr13 Steel Heat Treatment in Condition of Casting Mould
Autorzy:
Przyszlak, Natalia
Piwowarski, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/27314161.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
layered casting
bimetal
high chromium steel
grey cast iron
odlew warstwowy
stal wysokochromowa
żeliwo szare
Opis:
The paper presents issues related to the technology of layered castings manufactured in the system: working part made of high-chromium steel X46Cr13 - base part made of gray cast iron with flake graphite, using the mould cavity preparation technology. Considering the high hardenability of the above-mentioned steel grade, the aim of the research was to optimize the casting parameters of gray cast iron in such a way that it would be possible to perform heat treatment of X46Cr13 steel directly in the casting mould. As part of the research, the geometry of the working and base parts of layered castings was selected, and guidelines for mould technology from the point of view of the moulding sand were developed. In order to control the cooling rate, three matrix of the moulding sand were used - quartz sand, chromite sand and silicon carbide, with the same granularity. The thermal conductivity coefficient of sands made on selected matrix, bound with synthetic resin in the ratio of 30:1, was experimentally determined. Then, the bimetal casting process in a given mass was simulated in the MagmaSoft® (ver. 5.4.1). The purpose of the simulation was to determine the maximum virtual temperature Tm in the thermal center of the outer surface of the X46Cr13 steel insert. From the point of view of the research purpose, the insert was expected to heat up to the austenitization temperature, i.e. at least 950°C.
Źródło:
Archives of Foundry Engineering; 2023, 23, 2; 119--126
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the Heating Temperature of a Nickel-Chromium Steel Charge Material on the Stability of the Forging Process and the Durability of the Die
Autorzy:
Hawryluk, Marek R.
Lachowicz, Marzena
Janik, Marta
Gronostajski, Zbigniew
Stachowicz, Mateusz
Powiązania:
https://bibliotekanauki.pl/articles/28099626.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
forging
engine
chromium-nickel steel with austenitic microstructure
valve
forging tools
Opis:
The study discusses the issues of low durability of dies used in the first operation of producing a valve type forging from high nickel steel assigned for the application in motor truck engines. The analyzed process of manufacturing the exhaust valve forgings is realized in the coextrusion technology, followed by forging in closed dies. This process is difficult to master, mainly due to elevated adhesion of the charge material (high nickel steel - NCF3015) to the tool substrate as well as very high abrasive wear of the tool, most probably caused by the dissolution of hard carbide precipitates during the charge heating. A big temperature scatter of the charge during the heating and its short presence in the inductor prevents microstructure homogenization of the bearing roller and dissolution of hard precipitates. In effect, this causes an increase of the forging force and the pressures in the contact, which, in extreme cases, is the cause of the blocking of the forging already at the beginning of the process. In order to analyze this issue, complex investigations were conducted, which included: numerical modelling, dilatometric tests and hardness measurements. The microstructure examinations after the heating process pointed to lack of structure repeatability; the dilatometric tests determined the phase transformations, and the FEM results enabled an analysis of the process for different charge hardness values. On the basis of the conducted analyzes, it was found that the batch material heating process was not repeatable, because the collected samples showed a different amount of dissolved carbides in the microstructure, which translated into different hardnesses (from over 300 HV to 192 HV). Also, the results of numerical modeling showed that lower charge temperature translates into greater forces (by about 100 kN) and normal stresses (1000 MPa for the nominal process and 1500 MPa for a harder charge) and equivalent stresses in the tools (respectively: 1300 MPa and over 1800 MPa), as well as abrasive wear (3000 MPa mm; 4500 MPa mm). The obtained results determined the directions of further studies aiming at improvement of the production process and thus increase of tool durability.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 711--722
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ilościowa ocena i wydzielenie różnych form siarki w próbkach geologicznych wraz z zastosowaniem do badań pochodzenia związków siarki w systemach naftowych
Quantitative assessment and isolation of various sulphur forms in geological samples and its application in investigation of sulphur compounds origin in petroleum systems
Autorzy:
Wencel, Kinga
Bieleń, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/31343902.pdf
Data publikacji:
2023
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
kerogen
siarka redukowana chromem
CRS
warstwy menilitowe
bakteryjna redukcja siarczanów
analiza elementarna
izotopy siarki
chromium-reduced sulfur
Menilite Beds
bacterial sulfate reduction
elemental analysis
sulfur isotopes
Opis:
Siarka występuje w naturze w bogactwie form – jako siarka elementarna, siarczki, siarczany, organiczne związki siarki (OZS, ang. organic sulfur compounds, OSC). W pracy zbadano zależności pomiędzy występowaniem siarki w ropach i skałach macierzystych. Wydzielono siarkę pirytową, pierwiastkową, organiczną w kerogenie oraz OZS w bituminach. Do rozdzielenia siarki pirytowej pozostałej po izolacji kerogenu zastosowano metodę redukcji kwaśnym roztworem chlorku chromu (II) (ang. chromium reducible sulfur method, CRS), przeprowadzaną w inertnej atmosferze azotu w komorze rękawicowej. Zastosowanie CrCl2 w obecności HCl powoduje wydzielenie siarki pirytowej w postaci H2S. Siarkowodór jest następnie wprowadzany do roztworu AgNO3, gdzie zachodzi reakcja z wytrąceniem się czarnego osadu Ag2S. Ilość wytrąconej siarki była oznaczana wagowo, a kerogen i siarczek srebra (I) były poddawane badaniom izotopów siarki. Analiza elementarna badanego materiału przed usunięciem i po usunięciu siarki pirytowej oraz obliczenie stosunków atomowych H/C, O/C, N/C, S/C potwierdziły przydatność metody wykazanej w poprzednich badaniach i nie uwidoczniły istotnych zmian w badanym kerogenie. W pracy oddzielono siarkę pirytową od organicznej w kerogenie z wybranych próbek warstw menilitowych z zewnętrznych Karpat fliszowych oraz poddano obie formy tego pierwiastka badaniom izotopowym, a także skorelowano z danymi dotyczącymi innych form występowania siarki w skałach, bituminach i ropach. Co istotne, znaczną część siarki całkowitej w kerogenie stanowi siarka pirytowa, co implikuje konieczność rozdzielenia jej od siarki organicznej w celu sformułowania poprawnych wniosków dotyczących energii aktywacji kerogenu i tempa generacji węglowodorów. Badania izotopowe potwierdzają wcześniejsze interpretacje pochodzenia pirytu z procesu bakteryjnej redukcji siarczanów i euksynicznego środowiska depozycji oligoceńskich osadów w basenie Paratetydy.
Sulphur occurs in nature in a variety of forms: as elemental sulphur, sulphides, sulphates, and organic sulphur compounds (OSC). The work investigated the relationship between the presence of sulphur in crude oil and source rocks. Pyritic and organic sulphur was isolated in kerogen, while OSC and elemental sulphur was isolated in bitumens. The chromium reducible sulphur method (CRS) carried out in an inert nitrogen atmosphere in a glove box was used to separate pyritic sulphur remaining after kerogen isolation. The use of a CrCl2 solution in HCl results in the release of pyritic sulphur in the form of H2S. Hydrogen sulphide is later introduced into the AgNO3 solution, where reaction occurs resulting in precipitation of black Ag2S. The amount of precipitated sulphur was determined by weight, while kerogen remains and silver (I) sulphide underwent sulphur isotope testing. The elemental analysis of the tested material before and after the removal of pyritic sulphur and the calculation of the atomic H/C, O/C, N/C, S/C ratios confirmed the usefulness of the method demonstrated in previous studies and did not show any significant changes in the tested kerogen. In the work, pyritic sulphur was separated from organic sulphur in kerogen from selected samples of Menilite Beds from the Outer Carpathians and subjected to isotope tests, and correlated with data on other forms of sulphur occurrence in rocks, bitumens and crudes. A significant part of the total sulphur in kerogen is pyritic sulphur, which without determining the content of organic sulphur may lead to incorrect assumptions regarding the activation energy of kerogen and the rate of hydrocarbon generation. Isotopic studies confirm earlier interpretations of the origin of pyrite by bacterial reduction of sulphates and the euxinic environment of the deposition of Oligocene sediments in the Paratethys Basin.
Źródło:
Nafta-Gaz; 2023, 79, 6; 371-384
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Wear Mechanism of High-Chromium Gyratory Crusher Mantle Lining in Terms of the Assessment of the Used Material
Analiza zużycia stożka wewnętrznego kruszarki stożkowej pod kątem oceny zastosowanego materiału
Autorzy:
Bembenek, Michał
Krawczyk, Janusz
Zagórski, Krzysztof
Pawlik, Jan
Powiązania:
https://bibliotekanauki.pl/articles/27310181.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
gyratory crusher
erosion wear mechanism
high-chromium cast steel
kruszarki stożkowe
mechanizm zużycia erozyjnego
staliwo wysokochromowe
Opis:
After the rock is excavated in bulky chunks, it must be processed into fractions usable by diverse branches of industry. There are many approaches to achieving a fine aggregate, and the gyratory crusher is often preferable. Alas, since its working surfaces are subjected to heavy loads of abrasive material, the lining of the gyratory crusher is prone to specific geometry degeneration mechanisms. The authors subjected the mantle lining to a series of tests, such as metallurgical microstructure analysis, chemical composition and hardness evaluation and X-ray examination. Although most mantles are manufactured from the high-manganese Hadfield steel family, the lining was fabricated from high-chromium hypoeutectic white cast steel with a white iron structure. The difference in the chosen material's chemical composition resulted in an uncommon wear mechanism with visible inclined craters emerging in the lower part of the cone, where erosive, dynamically-moving particles were concentrated.
Po wydobyciu skały w dużych kawałkach wymaga ona przetworzenia na frakcje nadające się do wykorzystania przez różne gałęzie przemysłu. Istnieje wiele sposobów na uzyskanie drobnego kruszywa, a kruszarka stożkowa jest często preferowaną opcją. Niestety, jej powierzchnie robocze poddawane są dużym obciążeniom ściernym, co skutkuje tym, że wykładzina kruszarki stożkowej jest podatna na specyficzne mechanizmy degeneracji geometrii. Autorzy poddali wyłożenie stożka szeregowi badań, m.in. analizie mikrostruktury, ocenie składu chemicznego, rentgenowskiej analizie fazowej i twardości w odniesieniu do właściwości tribologicznych na podstawie analizy mechanizmu zużycia. Większość stożków jest wykonywana ze stali wysokomanganowej rodziny Hadfielda, w tym przypadku wyłożenie zostało wykonane z wysokochromowej, podeutektycznego staliwa o strukturze odpowiadającej żeliwu białemu. Zastosowany materiał spowodował występowanie charakterystycznego mechanizmu zużycia w postaci tworzenia się kraterów, gdzie zużycie erozyjne koncentruje się w dolnej części stożka, przy której koncentruje się oddziaływanie większych dynamicznie przemieszczających się cząstek.
Źródło:
Tribologia; 2023, 1; 27--40
0208-7774
Pojawia się w:
Tribologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Active Capping Treatment of Copper and Chromium Contaminated Sediment with Bentonite Kaolin and Sand to Inhibit their Release to the Overlying Water
Autorzy:
Aliyu, Mohammed Kabir
Abd Karim, Ahmad Tarmizi Bn
Chan, Chee Ming
Abdulkadir, Aeslina
Bin Daud, Zawawi
Oyekanmi, Adeleke Abdulrahman
Powiązania:
https://bibliotekanauki.pl/articles/2202312.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
in situ capping
polluted sediment
bentonite
kaolin
chromium
copper
Opis:
The public concern over sediment contamination brought on by mining operations, excessive use of chemical fertilisers or pesticides, industrial, agricultural, and municipal effluent, is increasing. Dredging is a more expensive treatment option than in situ capping of polluted sediment for immobilising pollutants in sediments on site. In order to stop the release of Cr and Cu from chemically contaminated sediments, this study aimed to evaluate the efficiency of utilising active capping materials such as bentonite (B), kaolin (K), and a 1:1 combination of bentonite and kaolin (BK) as capping materials. In a 90-day laboratory experiment carried out in glass tanks with a 1 cm thickness cover of capped material plus sand spread over the polluted sediment, the efficacy of B, K, and BK in inhibiting trace metal leachability was examined. The findings demonstrated that B and BK decreased the ability of sediments to leach Cr and Cu. The results suggest that BK and B should be considered as a suitable active material for capping treatment of polluted sediment sites because of their high Cu and Cr trapping. According to an analysis of adsorption kinetics, chemisorption was the adsorption process. The outcomes of this study demonstrated the potential for using kaolin, a bentonite-kaolin clay mixture covered with sand, and bentonite as capping materials for the in-situ treatment of Cr and Cu polluted coastal sediments.
Źródło:
Journal of Ecological Engineering; 2022, 23, 12; 264--272
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics and Adsorption Test of Activated Carbon from Indonesian Bituminous Coal
Autorzy:
Kusdarini, Esthi
Budianto, Agus
Powiązania:
https://bibliotekanauki.pl/articles/2202119.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
ammonium phosphate
coal
batik waste
activated carbon
chromium
Opis:
The fast-growing batik industry in Indonesia raises the problem of the waste containing chromium. One method to remove chromium is by the adsorption process using activated carbon. Activated carbon can be made from coal. This commodity is a mining mineral the availability of which is still abundant in Indonesia. This study aimed to obtain: 1) the best concentration of activator and activation temperature in the manufacture of activated carbon; 2) characteristics of activated carbon (moisture content, volatile matter content, ash content, fixed carbon content, iodine number, specific surface area, pore-volume, pore surface area, pore radius, and SEM photos); 3) % activated carbon removal for chromium and maximum adsorption capacity for chromium; 4) Freundlich and Langmuir isotherm adsorption equation of activated carbon to chromium. The manufacture of activated carbon was carried out by a carbonization process followed by a chemical and physical activation processes. The chemical activator was ammonium phosphate with doses of 74.5 g/L, 149 g/L, 223.5 g/L, and 298 g/L. Meanwhile, physical activation was carried out at 848 K, 948 K, 1048 K, and 1148 K. The next step was to test the adsorption capacity of activated carbon on artificial batik waste containing chromium. The results showed that: 1) activator concentration did not significantly affect the characteristics of activated carbon. Meanwhile, the optimal activation temperature is at a temperature of 1048 K and 1148 K, which can produce the activated carbon that meets the requirements of activated carbon of the Indonesian National Standard 06-3730-1995 with the following contents: air content 0.16–0.81%; volatile matter 14.62–19.31%; ash 6.48–9.97%; fixed carbon 70.60–75.79%; iodine number 1243.13–1258.65%; specific surface area 31.930 m2/g; activated carbon pore volume 0.011 cc/g; pore surface area 8.905 m2/g; activated carbon pore radius 30.614; 3) the proportion of activated carbon removal for chromium is 37–53% and the maximum adsorption capacity for chromium is 52 mg/g; 4) the Freundlich equation test resulted in a constant R2 of 0.5126, n 2.4870, KF 8.8818 mg/g, while the Langmuir equation test resulted in a constant R2 of 0.8897, b -0.0075 L/mg, qm -90.0901 mg/g.
Źródło:
Journal of Ecological Engineering; 2022, 23, 10; 129--138
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Chromium Picolinate and Chromium Nanoparticles Added to Low- or High-Fat Diets on Chromium Biodistribution and the Blood Level of Selected Minerals in Rats
Autorzy:
Stępniowska, Anna
Juśkiewicz, Jerzy
Tutaj, Krzysztof
Fotschki, Joanna
Fotschki, Bartosz
Ognik, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/2159288.pdf
Data publikacji:
2022-09-05
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
minerals
chromium
nanoparticles
high-fat diet
Opis:
The metabolism of chromium (Cr), calcium (Ca), phosphorus (P), iron (Fe), copper (Cu), and zinc (Zn) is interconnected, and their deficiency or excessive accumulation may lead to various disturbances, including anemia and diabetes. The current research was undertaken to determine whether low-fat or high-fat diets with the Cr(III) addition in the form of picolinate (CrPic) or nanoparticles (CrNPs) have an interactive effect on the retention and accumulation of this element in organs and the content of P, Ca, Fe, Cu and Zn in the blood plasma of rats. The experiment was performed using 48 outbred male Wistar rats fed a low-fat or high-fat semi-purified rat diet with dietary addition of chromium at a dose of 0.3 mg/kg body weight. The obtained results point to the paramount importance of the dietary Cr form on the excretion pattern of this microelement. It has been found that CrNPs were to a greater extent excreted from the rat’s body via urine and feces in comparison to CrPic, as indicated by the values of the Cr retention index (44.4 vs. 65.9%, respectively). The additional dietary Cr, irrespective of its form and diet type, was not accumulated in the analyzed internal organs, i.e. brain, spleen, kidneys, liver, thigh bone, and thigh muscle. It should be stressed that dietary CrPic, unlike CrNPs, added to the high-fat diet adversely reduced plasma concentration of vital minerals in comparison to the levels observed in rats fed the low-fat diet, i.e. Zn (60.5 vs. 69.9 µM), Cu (13.6 vs. 15.7 µM), and P (1.12 vs. 1.30 µM). In turn, the CrNPs, but not CrPic, added to the high-fat diet decreased plasma Fe level (1.41 vs. 2.43 µM).
Źródło:
Polish Journal of Food and Nutrition Sciences; 2022, 72, 3; 229-238
1230-0322
2083-6007
Pojawia się w:
Polish Journal of Food and Nutrition Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fate and Management of Pollution of Hexavalent Chromium Cr(VI) and Heavy Metals in the Zarqa River Basin in Jordan
Autorzy:
Shammout, Maisa'a W.
Shatanawi, Muhammad
Awwad, Akl M.
Powiązania:
https://bibliotekanauki.pl/articles/2026728.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
Zarqa River Basin
industrial activity
water pollution
hexavalent chromium
Cr(VI)
heavy metals
decision maker
Opis:
This paper focused on the fate of pollution and management of hexavalent chromium Cr(VI) and heavy metals in the Zarqa River Basin in Jordan. The Zarqa River basin was selected in this research because it contains the majority of Jordanian industries, which are the main source of pollutants including Cr(VI) and heavy metals. This will help in assisting water resource management organizations in decision making when coping with pollution. Industries related to sources and impacts of Cr(VI) and heavy metals were identified, and the administration measures were highlighted according to their role in improving water quality. An analysis of water samples along the Zarqa River was conducted between 2016-2019 to evaluate the heavy metals concentrations and compare the results with the Jordanian standards. Findings showed that Cr(VI) was below the allowable limits (<5 μg/l), and the heavy metals were within the allowed limits set forth in the Jordanian Standard. The ranges of water analysis values (μg/L) were; DO 4640–6480, Fe <40–80, Mn 20–128, Co <20–30, Pb 80–190, Zn 70–100, and Cu <80–190, Al 700–730, V <70–100, B <300–351, Si 1100–1800, Ni 30, and Cd <10. These findings indicated that the quality of the Zarqa River would not cause hazardous effects. However, this was not the case few years ago due the current protection measures. At present some industries have been relocated from the Zarqa Basin to an area that does not pose any environmental hazards, while the rest of industries remained in the basin, but they have established an on-site treatment plant for industrial waste under the control of Jordanian government, and the enforcement of the environmental protection law. These measures must be monitored and updated by decision makers in a sustainable manner to prevent any water pollution.
Źródło:
Journal of Ecological Engineering; 2022, 23, 2; 108-115
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prekatalizatory oligomeryzacji olefin oparte na kationach chromu(III) oraz kobaltu(II) : właściwości fizykochemiczne oraz katalityczne
Precatalysts for olefin oligomerization based on chromium(III) and cobalt(II) cations : physicochemical and catalytic properties
Autorzy:
Malinowski, Jacek
Drzeżdżon, Joanna
Sikorski, Artur
Jacewicz, Dagmara Elżbieta
Powiązania:
https://bibliotekanauki.pl/articles/2200439.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kation chromu(III)
oligomeryzacja olefin
2-chloro-2-propen-1-ol
aktywność katalityczna
MALDI-TOF MS
chromium(III)
olefin oligomerization
catalytic activity
Opis:
The introduction describes the most important facts about the development of polyolefins. This is followed by a description of the role of polyolefins and the most important applications in industry and everyday life. The paper presents new, highly active precatalysts for oligomerization of olefins. These are coordination compounds based on chromium(III) cation, anions of various polycarboxylic acids and auxiliary ligands, such as 1,10-phenanthroline or 2,2'-bipyridyl. This review presents their crystallographic structures and basic parameters describing the elementary cell. The catalytic properties of the obtained oligomerization products using chromium(III) coordination compounds by MALDI-TOF MS are described. In conclusion, the presented precatalysts are compared with others described in the literature.
Źródło:
Wiadomości Chemiczne; 2022, 76, 11-12; 943--962
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quick and simple speciation analysis of chromium in cements
Autorzy:
Grabarczyk, Malgorzata
Wardak, Cecylia
Powiązania:
https://bibliotekanauki.pl/articles/2146952.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cement
extraction
chromium speciation
voltammetric determination
Opis:
The extraction of total Cr(VI) from commercially available cements, based on DTPA + 0.2 mol dm-3 (NH4)2SO4/NH4OH mixture solution and subsequent selective determination of Cr(VI) has been proposed. The determination was carried out using the adsorptive voltammetric stripping method. The study was conducted using three different commercially available cement samples. It has been checked that the proposed extraction procedure guaranteed no changes of chromium speciation during cement analysis. For comparison extraction was also carried out with the use of recommended by United States Environmental Protection Agency (EPA) Method 3060A, based on 0.28 mol dm-3 Na2CO3 + 0.5 mol dm-3 NaOH). Additionally, the extraction process was carried out using only distilled water as an extraction mixture which allows to evaluate concentration of only soluble Cr(VI) forms contained in cement. In all three cements, the content of soluble Cr(VI) was below 2 ppm, i.e. the limit value by European Union Directive 2003/53/EC.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 2; art. no. 144445
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Siarka organiczna i pirytowa: metody wydzielania i oceny ilościowej. Wpływ zawartości siarki organicznej na energię aktywacji kerogenu
Organic and pyritic sulphur: methods of separation and quantitative determination. Effect of organic sulphur concentration on kerogen activation energy
Autorzy:
Wencel, Kinga
Powiązania:
https://bibliotekanauki.pl/articles/2143363.pdf
Data publikacji:
2022
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
siarka organiczna
kerogen
analiza elementarna
usuwanie
siarka pirytowa
metoda ekstrakcji chlorkiem chromu(II)
organic sulphur
elemental analysis
pyritic sulphur
removal
chromium(II) chloride extraction method
Opis:
Siarka organiczna odgrywa ogromną rolę w procesach diagenezy substancji organicznej, wpływając na tempo jej termicznych przemian. Oszacowanie ilości siarki organicznej w kerogenie pozwala na lepsze zrozumienie mechanizmów generacji węglowodorów. Standardowe metody izolacji kerogenu przy użyciu kwasów HCl/HF usuwają większość minerałów i często pozostawiają znaczne ilości pirytu, który stanowi przeszkodę w określeniu składu pierwiastkowego kerogenu i rozkładu grup funkcyjnych. Głównym zagadnieniem pracy było oszacowanie ilości siarki organicznej i pirytowej w kerogenie w sposób niepowodujący istotnych przemian w próbce wyjściowej. W celu usunięcia siarki pirytowej w wybranych próbkach zastosowano metody tradycyjne zakładające wykorzystanie kwasu azotowego oraz metodę redukcji kwaśnym roztworem chlorku chromu(II) (ang. chromium reducible sulphur, CRS), przeprowadzaną w inertnej atmosferze w specjalnie skonstruowanej komorze rękawicowej. Siarkę pirytową ekstrahowaną HNO3 i utlenianą do siarczanów oznaczano wagowo w formie strąconej jako BaSO4 lub za pomocą miareczkowania redoksometrycznego roztworem K2Cr2O7 jako siarkę związaną z żelazem. Zastosowanie kwaśnego roztworu CrCl2 powoduje wydzielenie H2S, który jest wprowadzany do roztworu Zn(CH3COO)2, gdzie siarka wytrąca się w postaci ZnS, a następnie jej ilość jest oznaczana jodometrycznie za pomocą Na2S2O3. Porównano wykorzystane metody pod kątem ich praktycznego zastosowania, powtarzalności wyników oraz wpływu na analizowaną próbkę. Analiza elementarna badanego materiału przed usunięciem i po usunięciu siarki pirytowej oraz obliczenie stosunków atomowych H/C, O/C, N/C, S/C wykazały przemiany zachodzące w substancji organicznej po zastosowaniu metod utleniających. W przeciwieństwie do metod tradycyjnych użycie roztworu CrCl2 nie powoduje takich przemian, co pozwala na dalsze analizy wymagające uprzedniego usunięcia pirytu z kerogenu. Podjęto próbę korelacji ilości siarki organicznej z energią aktywacji kerogenu wyznaczoną na aparacie Rock-Eval. Zauważono wpływ trawienia próbki kwasami na określanie energii aktywacji kerogenu, której wartość wzrasta wraz z użyciem próbek poddanych kolejnym etapom preparatyki, obejmującym izolację kerogenu i usunięcie siarki pirytowej.
Organic sulphur plays a significant role in diagenesis of organic matter, influencing the rate of thermal alteration. Determining organic sulphur content in kerogen gives a better comprehension of hydrocarbon generation mechanisms. Standard kerogen isolation treatment using HCl/HF acids removes most mineral components and often leaves significant amounts of pyrite, which is an obstacle to determining the elemental composition and functional group distributions in kerogen. The main aim of this research was to determine the organic and pyritic sulphur content in kerogen in a way that does not cause significant alteration of initial sample. In order to remove pyritic sulphur, designated samples were treated using traditional methods involving the use of nitric acid(V) and more recent method of acidic chromium chloride(II) reduction conducted under inert atmosphere in especially designed glovebox. Pyritic sulphur extracted in HNO3 and oxidised into sulphates was determined in a form of BaSO4 or as an iron-sulphur bond by redox titration using solution of K2Cr2O7 as titrant. The use of acidic CrCl2 solution converts pyritic sulphur to H2S, which is led to Zn(CH3COO)2 solution and precipitated as ZnS, and consequently the amount of sulphur is determined by iodometric titration with use of Na2S2O3. Practical application, repeatability of results, and an effect on the sample of each method were examined. Elemental analysis and comparison of H/C, O/C, N/C, S/C atomic ratios before and after pyrite removal treatment has shown alternation of organic matter in samples subjected to oxidizing methods. In contrast to traditional method, CrCl2 solution does not cause such changes and allows for further analyses, which require prior pyrite removal. An attempt was made to correlate organic sulphur content with kerogen activation energy measured on the Rock Eval apparatus. There is a visible influence of acids digestion on the determination of kerogen activation energy, which increases when using samples subjected to subsequent stages of kerogen isolation and pyritic sulphur removal treatments.
Źródło:
Nafta-Gaz; 2022, 78, 2; 97-109
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption method of purification of stocks from chromium(III) ions by bentonite clays
Autorzy:
Soloviy, Christina
Malovanyy, Myroslav
Palamarchuk, Olga
Trach, Iryna
Petruk, Halyna
Sakalova, Halyna
Vasylinych, Tamara
Vronska, Nataliya
Powiązania:
https://bibliotekanauki.pl/articles/1844378.pdf
Data publikacji:
2021
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
adsorption
bentonite
chromium ions
environmental safety
natural clay sorbents
wastewater purification
Opis:
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.
Źródło:
Journal of Water and Land Development; 2021, 48; 99-104
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Can the effects of chromium compounds exposure be modulated by vitamins and microelements?
Autorzy:
Sijko, Monika
Janasik, Beata
Wąsowicz, Wojciech
Kozłowska, Lucyna
Powiązania:
https://bibliotekanauki.pl/articles/2086573.pdf
Data publikacji:
2021-08-05
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
zinc
folic acid
selenium
hexavalent chromium
vitamin E
vitamin C
Opis:
Chromium (Cr) is a very common element. It occurs in 2 oxidation states, Cr(III) and Cr(VI). Although Cr(III) is not considered an element essential for mammals, it raises lots of controversy due to its role in the body. While Cr(III) action should be considered an effect of pharmacological action, Cr(VI) is included in the first group of carcinogens for humans. Moreover, it induces numerous pathological changes in the respiratory, urinary, reproductive and digestive systems. In addition, Cr(VI) is used in many industry branches, causing millions of workers all over the world to be exposed to Cr(VI) compounds. A considerable number of the occupationally exposed individuals are in favor of a deep analysis of the mechanisms of Cr(VI) action and a search for a way to reduce its negative impact on the human body. Numerous reactive oxygen species inducing oxidative stress and causing various damage are produced during Cr(VI) reduction in the cells. A good balance between antioxidants and pro-oxidants can reduce Cr(VI)-induced damage. The influence of vitamins and microelements on the adverse Cr(VI) effects has no systematic research results summary. Therefore, this work focuses on the role of dietary antioxidants such as vitamins and microelements in the prevention of Cr(VI) adverse health effects. Numerous studies have revealed a protective influence of vitamins (mainly vitamins E and C) as well as microelements (especially selenium) on the reduction of Cr(VI)-induced adverse changes. A potential protective effect of these ingredients may be useful in occupational groups that are particularly exposed to Cr(VI). However, more research in this area is required.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2021, 34, 4; 461-490
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
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