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EN
The olefin polymerization catalysts constitute a large group of various compounds. Metallocene complexes are the largest part of this group. However, due to the instability at industrial plastics temperatures and the decomposition of complexes after MAO (or MMAO) activation, they have been partly replaced by non-metallocene compounds. This article concerns the studies on new non- metallocene precatalysts for the olefin polymerization and oligomerization. The report focuses on the structure and the catalytic activities of the complexes of chromium(III), vanadium(IV) and cobalt(II) with the following ligands: dipicolinate, 2-pyridinecarboxylate, oxalate, oxydiacetate, iminodiacetate, 2,2’- bipyridine, 4,4’-dimethoxy-2,2’-bipyridine, 1,10-phenantroline. These complex compounds are highly active precatalysts for olefin polymerization and oligomerization. The complexes: [Cr(dipic)2][Cr(bipy)(dipic)H20]-2H20 and [Cr(dipic) 2]Hdmbipy2.5H20 deserve special attention because they are new type of the precatalysts i.e. organic salt type complexes composed both of organic cations and anions. These compounds are not only interesting because of their structure but also because of their high catalytic activity.
EN
This paper presents the results of the study on the extraction capacity of 1,8,15,22-tetra(1- heptyl)resorcin[4]arene and its octasubstituted derivatives containing thiophosphoryl, ester and amide groups in the presence of Pb(II), Zn(II), Cd(II) and Cr(III) in solvent extraction process. Effects of the structure and concentration of the resorcinarene extractant and the composition of the aqueous phase as well as its acidity on the efficiency and selectivity of removal of the examined metal ions from model aqueous solutions were determined. The 1:1 stoichiometry for complexes formed between Pb(II) and Cr(III) and the octasubstituted resorcin[4]arenes was determined by classical slope analysis and loading test.
EN
Zn/Cr and Zn/Cr layered double hydroxides (LDHs) intercalated with Keggin ion [α-SiW12O40]4-were successfully synthesized at room temperature and pH value of 10. The synthesized materials were characterized by means of the XRD, BET, and FT-IR analyses and used as an adsorbent iron(II). The adsorption process was investigated by studying pH, the kinetics, and thermodynamic properties of the adsorption process. The results showed the interlayer Zn/Cr LDHs was 7.53 Å and increase to 10.26 Å on Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4-. The BET analysis showed that the pore volume of both materials increased from 0.063 cm3 g-1 to 0.163 cm3 g-1. The pH point zero charge measurement for the Zn/Cr LDHs material was 10 while LDHs Zn/Cr intercalated with Keggin ion [α-SiW12O40]4- was 8. Zn/Cr LDHs intercalated with Keggin ion [α-SiW12O40]4- has higher adsorption capacity than Zn/Cr LDHs without intercalation. Desorption of iron (III) was successfully conducted using HCl as reagent showing the involvement of ion exchange in the adsorption.
EN
In the paper, the assessment of the impact of heavy metals on water objects, namely copper and chromium was performed, and the methods for their neutralization were defined. A scientifically grounded method for the selection of natural zeolite for the purification of wastewater from heavy metals has been developed, provided that they are jointly present. The physicochemical characteristics of two metals related to heavy metals are presented: copper and chromium. The methods for determining the sorption capacity of natural zeolite for copper and chromium compounds, as well as the methods of analytical control of the wastewater components were presented. The results of the experimental studies on the combined adsorption of copper and chromium cations by natural zeolite under static conditions were presented. The changes in the chemical composition of the zeolite surface as a result of heavy metal sorption have been investigated. The influence of the nature of the ions and the pH of the adsorption medium on the selectivity of the heavy metal ions extraction by zeolite was analyzed. A diagram of the composition of the solution, depending on the pH values, was constructed. The pH of the beginning of deposition of the corresponding heavy metal hydroxides on the zeolite surface was calculated. While analyzing the results of experimental studies on the combined adsorption of copper and chromium ions, it was found that the copper ions are significantly better adsorbed by the sorbent than the chromium ions. Despite the same concentration of the chromium and copper ions in solution, Cu2+ is extracted selectively. As can be seen from the results of experimental studies, the concentration of copper on the surface of the sorbent increases from 0.628% mass at a concentration of 0.01 g/dm3 to 47.380% mass at a concentration of 1 g/dm3. The studies on the static activity of clinoptilolite for the copper and chromium ions indicate a simultaneous mechanism of the process, which involves ion exchange and physical adsorption. The concentration of the chromium ions on the surface of the sorbent after adsorption depends on the increase of the concentration of Cr3+ in the original solution to a lesser extent. The results of the studies on the combined adsorption of the Cu2+ and Cr3+ ions indicate the possibility of their chromatographic separation, which makes their further use possible.
EN
The Ecotourism Mangrove Forest at Wonorejo in East Coast Surabaya area is one of large mangrove forests inside in the metropolitan city in Indonesia. There are many ecological values of the mangrove forest in most tropical countries such as sea fisheries, place of sea and coastal animals, sea and brackish water quality protecting the endangered mangrove coastlines and development of human life. The role of mangrove in increasing the sea and brackish water quality can be shown through many processes such as cycling of nutrients, particulate matter and some pollutants in water and sediment around the mangrove plants. One of the inorganic pollutants that can be removed by mangrove are heavy metals, such as chromium (Cr). The Wonorejo River is one of the rivers that receive the disposal of wastewater in Surabaya East Coast area. Large quantitites of wastewater from industries and households were released to this river. The concentration of Cr at the Wonorejo Estuary reached 0.0325 mg/L and 2.7761 mg/L in sediments. The purpose of this research was to determine the potency of Cr accumulation by Avicennia alba that was grown for ten years at Wonorejo Ecotourism Mangrove Forest. The sampling activities were conducted using a transect quadrat sampling method with a 10x10 m dimension. The sediment and mangrove root samples were extracted before being analysed using an atomic absorption spectrophotometer (AAS). The results showed that the Cr accumulation by roots of A. alba reached 25.4 ± 1.6 to 55.3 ± 1.1. The BCF value in A. alba were 0.32 ± 0.01 to 0.83 ± 0.5 with the concentration Cr in sediment were 60 ± 1.4 to 79.3 ± 1.1. A. alba showed potential as a moderate accumulator for Cr. In conclusion, A. alba can be considered for use in phyto-monitoring and phytoremediation of Cr in coastal areas.
PL
W pracy opisano metodę oraz wyniki oznaczenia dwóch form specjacyjnych chromu w wodach, pochodzących z sześciu artezyjskich studni głębinowych, znajdujących się na terenie miasta Krakowa. Powodem celowości oznaczenia chromu w wodach głębinowych, przeznaczonych do spożycia są silnie zróżnicowane właściwości jonów chromu (III) i chromu (VI) szczególnie jeżeli chodzi o ich wpływ na organizm ludzki. Chrom(III) jest zaliczany do mikroelementów niezbędnych do prawidłowego funkcjonowania i rozwoju organizmu. Chrom (Vl) ma negatywny wpływ, gdyż przypisuje się mu działanie mutagenne, a nawet kancerogenne. Jako metodę specjacyjnego oznaczania obu form jonów chromu wybrano katalityczno-adsorpcyjną woltamperometrię stripingową (CAdSV) połączoną z rejestracją katodowych woltamogramów techniką impulsej woltamperometrii różnicowej (DPV). Spośród wielu znanych metod instrumentalnych metoda DP CAdSV cechuje się największą precyzją, dokładnością i czułością pomiaru. Co szczególnie ważne próbki wody przeznaczone do analizy woltamperometryczej nie wymagają wstępnego przygotowania, w efekcie metoda spełnia rygorystyczne wymagania zielonej chemii analitycznej (ang. Green Analytical Chemistry).
EN
The publication describes the method and results of determination of chromium speciation forms in deep-water samples. The samples came from six deep wells located in the city of Cracow. The reason for the determination of chromium in water is the different properties of Cr(III) and Cr(Vl) ions, especially their effect on the human body. Chromium (III) is essential for the proper functioning and development of the organism. Chromium (VI) has a negative effect because it acts mutagenically and even carcinogenically. The catalytic adsorptive stripping voltammetry (CAdSV) has been chosen as the method of chromium quantitative determination. Differential pulse voltammetry (DPV) technique was used to record cathodic voltammograms. Among the many instrumental methods, the DP CAdSV is characterized by the highest precision, accuracy, and sensitivity of measurements. It is important that the water samples intended for this analysis do not require any preliminary preparation, so the method meets the requirements of Green Analytical Chemistry.
7
Content available remote Badanie akumulacji wybranych metali w wodzie z różnych ujęć rzeki Wisły
PL
Celem niniejszej pracy było zbadanie stężeń różnych ujęciach rzeki. Oznaczenie stężenia manganu i żelaza wykonano wykorzystując metodę absorpcyjnej spektrometrii atomowej (ASA), a stężenie chromu oznaczono przy użyciu metody impulsowej woltamperometrii różnicowej adsorpcyjnej strippingowej (DP-AdSV) w układzie z elektrodą rtęciową jako elektrodą pracującą. Przeprowadzone badania nie wykazały przekroczenia dopuszczalnych stężeń oznaczanych pierwiastków w wodzie. Szczególną uwagę zwrócono na próbkę wody pobraną tuż za miejscem zrzutu nieoczyszczonych ścieków komunalnych do rzeki po awarii oczyszczalni ścieków „Czajka" w Warszawie, jednak nie wykazała ona odstępstw od normy. Uzyskane wyniki porównano z obowiązującymi normami.
EN
The aim of this work was to determine the chosen metals concentration in water derived from Vistula River in Cracow and Warsaw. Three water samples were collected from different parts of the river. Atomic Absorption Spectrometry (AAS) was used to determine the concentrations of manganese and iron, whereas measurements of chromium concentration were carried out using differential voltammetry in the system with the CGMDE electrode as a working electrode. The conducted research did not show that the permissible concentrations of the elements in water were exceeded. Particular attention was paid to the water sample collected just after the discharge site of untreated municipal sewage to the Vistula river after the failure of the "Czajka" sewage treatment plant in Warsaw, but it did not show any deviation from the norm. The obtained results were compared with the applicable standards.
8
Content available Teoretyczne badania katalizatora CrOx/SiO2
EN
The Phillips CrOx/SiO2 catalyst is one of the most commonly used system in the industrial production of high-density polyethylene (HDPE). This system has been extensively studied since decades, mainly by means of experimental techniques. However, the progress in determination of the nature of the chromium sites and understanding of surface reactions occurring has been rather not satisfying and many issues are still under debate. Among others, structure of the chromium oxide species on the surface of the reduced catalyst is not well defined. Likewise, the mechanism of the catalyst reduction and active site formation is not well established. Many experimental studies indicate that chromium exists on the surface of amorphous silica in a wide variety of different forms including monomeric, dimeric and polymeric species. Different oxidation states are also possible, as Cr(VI), Cr(V), Cr(IV), Cr(III), Cr(II) were detected. There is a general consensuses that Cr(VI) dominates at the surface after the catalyst preparation, while Cr(II) and Cr(III) are mainly formed after contact with a reducing agent, like ethylene or CO. Nevertheless, the detailed structure of these oxide species, as well as the active sites, is still strongly discussed. As experimental studies do not show a clear picture about the nature of silica-supported chromium catalyst, very helpful can be computational approach which can provide complementary information, not accessible by experimental techniques. In this short review we summarize the recent progress in the field of the Phillips (CrOx/SiO2) catalyst focusing on the most relevant theoretical papers that were published within last couple of years. We also highlight the need of applying advanced models if realistic theoretical description of the CrOx/SiO2 system is to be achieved. Additionally, different computational approaches in modeling of heterogenous catalysts are discussed.
EN
This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.
EN
This study focused on reducing total chromium levels in raw wastewater from the leather tanning industry via electrocoagulation to comply with maximum permissible limits (MPL) and to determine the effects of main process parameters. An electrocoagulation reactor was built using aluminum electrodes as an anode and cathode. Then, the response surface methodology was applied using a 3k factorial design considering three factors, namely current intensity, treatment time, and pH. The total chromium removal percentage was considered as a response variable. 99% of the total chromium found in wastewater could be removed after 14-min treatment at 2-A current intensity and pH 5.5. Similar amount of chromium was removed at pH of 8.5 and 7. Statistical analysis performed at a confidence level of p < 0.05 revealed that all three factors influenced electrocoagulation. Total chromium could be efficiently removed from raw wastewater at a current intensity of 2.9 A, a pH of 8.4, and a treatment time of 21 min, suggesting that electrocoagulation using aluminum electrodes is an efficient method for total chromium removal. Thus, this process must be considered as a solution to the problems caused by the leather tanning industry and for better compliance with the MPL established in the Peruvian environmental standards.
EN
Biosorption is fast, effective and low cost process. It takes place in a wide range of temperature and it can be used for almost all types of heavy metals. The aim of this study was to investigate the ability of locally collected green macro algae to remove copper, chromium and cadmium from synthetic wastewater. The fresh algae were converted into dry powder as biosorbent. In the investigations, 1 g of macro algae powder was exposed to synthetic waste water contaminated with 10 mg/L concentration of copper, chromium and cadmium in separate exposure for 2 hours. The best removal efficiency for copper, chromium and cadmium were 70%, 80% and 85%, respectively, from the initial concentration of 10 mg/L. While macro algae are abundantly available in marshlands of south Iraq, it can be preferably utilized as biosorbent to remove heavy metals from the industrial wastewater.
EN
The aim of the study was to determine the effect of increasing doses of cobalt (0, 20, 40, 80, 160, 320 mg/kg d.m. of soil) on the total content of trace elements in soil after application of manure, clay, charcoal, zeolite and calcium oxide. The neutralizing substances were applied at 2% of the soil weight, and calcium oxide at a dose corresponding to one hydrolytic acidity. The content of the cobalt, cadmium, lead, chromium, nickel, zinc, copper, manganese and iron was determined in soil. The contamination of soil with cobalt and the application of neutralizing substances had significant effects on the total content of trace elements in soil In the series without substances, the soil contamination with cobalt increased the content of cobalt, lead, chromium, nickel and zinc in soil. All the neutralizing substances reduced the content of cobalt, manganese and iron in soil. The highest decrease in the cobalt content was observed in the series with manure, whereas the highest decrease in zinc occurred after addition of charcoal. The decrease in the content of the other metals (except nickel and lead) was observed in the pots with CaO and zeolite. The effect of other neutralizing substances depended on the trace element.
EN
To investigate the adsorptive properties of a local laterite deposited in Chenzhou, Hunan province, China, the adsorptive properties of the natural laterite were investigated by batch technique in this study. The effects of contact time, pH, ionic strength, temperature, and the concentration on adsorption properties were also analyzed. The obtained experimental results show that the main mineral composition of laterite is kaolinite and montmorillonite. The adsorption process achieved equilibrium within 60 minutes and 90 minutes for Sr(II) and Cr(VI), respectively. The adsorption capacities for Cr(VI) and Sr(II) by the laterite were about 7.25 mg·g-1 and 8.35 mg·g-1 under the given experimental conditions, respectively. The equilibrium adsorption data were fitted to the second-order kinetic equation. The adsorption capacity for Sr(II) onto the laterite increased with increasing pH from 3–11 but decreased with increasing ionic strength from 0.001 to 1.0 M NaCl. The Sr(II) adsorption reaction on laterite was endothermic and the process of adsorption was favored at high temperature. Similarly, the adsorption capacity for Cr(VI) onto the laterite increased with increasing pH from 3–11, however, the ionic strength and temperature had an insignificant effect on Cr(VI) adsorption. The adsorption of Cr(VI) and Sr(II) was dominated by ion exchange and surface complexation in this work. Furthermore, the Langmuir and Freundlich adsorption isotherm model was used for the description of the adsorption process. The results suggest that the studied laterite samples can be effectively used for the treatment of contaminated wastewaters.
PL
W pracy przedstawiono wyniki badań siluminu podeutektycznego z dodatkiem chromu przeznaczonego do odlewania pod ciśnieniem. W charakterze stopu wyjściowego zastosowano silumin o składzie chemicznym zbliżonym do siluminu gatunku EN AC-46000. W celu wprowadzenia chromu do siluminu wyjściowego zastosowano zaprawę AlCr15. Ilość siluminu wyjściowego oraz zaprawy AlCr15 dobrano w proporcjach pozwalających na uzyskanie w stopie zawartości Cr około 0,1; 0,2; 0,3; 0,4 i 0,5% wag. W ramach realizacji pracy zbadano zarówno silumin wyjściowy, jak również siluminy z dodatkiem chromu. Przedstawiono wyniki analizy termicznej i derywacyjnej ATD (ang. Differential Thermal Analysis – DTA), przeprowadzonej w celu zbadania procesu krystalizacji siluminów. Pokazano mikrostrukturę siluminów odlewanych do próbnika ATD oraz ciśnieniowo. Określono podstawowe właściwości mechaniczne siluminów odlewanych pod ciśnieniem. Przedstawione wyniki analizy ATD wykazały wpływ dodatku chromu na przebieg procesu krystalizacji badanego siluminu. Na krzywych ATD siluminu wyjściowego występują trzy efekty cieplne wywołane odpowiednio krystalizacją roztworu stałego α(Al), oraz dwóch eutektyk α + Al15(Fe,Mn)3Si2 + + β i α + Al2Cu + AlSiCuFeMnMgNi + β. Wprowadzenie chromu w ilości około 0,2% wag. spowodowało wystąpienie na krzywej derywacyjnej dodatkowego efektu cieplnego pochodzącego od krystalizacji fazy międzymetalicznej zawierającej chrom. Krystalizacja tej fazy zachodzi przed wydzielaniem się z cieczy dendrytów fazy α(Al). Analiza mikrostruktury siluminów odlewanych do próbnika ATD wykazała pojawienie się wydzieleń „nowej” fazy w siluminach zawierających 0,2% wag. lub więcej Cr. Wraz z pojawieniem się na krzywych ATD dodatkowego efektu cieplnego oraz „nowej” fazy w mikrostrukturze siluminu zauważono brak fazy Al15(Fe,Mn)3Si2. W siluminach odlewanych ciśnieniowo dodatek chromu również spowodował powstanie „nowej” fazy międzymetalicznej. Faza ta pojawia się przy zawartości około 0,3% wag. lub większej Cr. Ma ona morfologię zbliżoną do ścianowej. Wraz z podwyższaniem ilości chromu rozmiary tej fazy znacząco się zwiększają. Badania podstawowych właściwości mechanicznych siluminów odlewanych pod ciśnieniem wykazały, że dodatek Cr daje możliwość znaczącego podwyższenia głównie wytrzymałości na rozciąganie Rm i wydłużenia względnego A. Pierwiastek ten w mniejszym stopniu wpłynął na podwyższenie twardości HB. Wartości umownej granicy plastyczności Rp0,2 siluminu wyjściowego i siluminów z podwyższoną zawartością chromu nie zmieniają się istotnie. Najwyższe właściwości mechaniczne uzyskano dla siluminów zawierających około 0,2 i 0,3% wag. Cr.
EN
The paper presents the results of studies of hypoeutectic silumin with a chromium addition used for pressure casting. A silumin with the composition similar to that of EN AC-46000 was used as the initial one. In order to introduce chromium into the initial silumin, an AlCr15 master alloy was applied. The amounts of the initial silumin and the AlCr15 master alloy were selected in the proportions making it possible to obtain about 0.1; 0.2; 0.3; 0.4 and 0.5 wt. % of Cr in the alloy. Both the initial silumin and the silumins with the chromium addition were examined. The results of the thermal and derivational analysis performed to investigate the silumins' crystallization process have been presented. The microstructure of the silumins cast into an DTA tester and under pressure has been demonstrated. The basic mechanical properties of the pressure cast silumins have been presented. The results of the DTA analysis showed an effect of the chromium addition on the course of the crystallization process of the examined silumin. Three thermal effects are present on the silumin's DTA curves, caused by the crystallization of the solid solution α(Al), and of two eutectics α + Al15(Fe,Mn)3Si2 + β and α + Al2Cu + AlSiCuFeMnMgNi + + β. The introduction of chromium in the amount of about 0.2 wt. % caused the presence of an additional thermal effect on the derivation curve, originating from the crystallization of the intermetallic phase containing chromium. The crystallization of this phase occurs before the precipitation of the dendrites of phase α(Al) from the liquid. The microstructure analysis of the silumins cast into the DTA tester showed the presence of precipitations of a “new” phase in the silumins containing 0.2% wt. Cr or more. With the occurrence of an additional thermal effect on the DTA curves as well as the “new” phase in the silumin's microstructure, the lack of phase Al15(Fe,Mn)3Si2 was observed. In the pressure cast silumins, the chromium addition also caused the formation of a “new” intermetallic phase, which occurs with the Cr content of about 0.3 wt. % or more. Its morphology is similar to a faceted one. With an increase of the chromium content, the size of this phase significantly increases as well. The investigations of the basic mechanical properties of the pressure cast silumins showed that the Cr addition makes it possible to significantly increase mainly the tensile strength Rm and the unit elongation A. To a lesser extent, this element caused an increase of the hardness HB. The values of the proof stress Rp0.2 of the initial silumin and the silumins with an increased chromium content do not change significantly. The highest mechanical properties were obtained for the silumins containing about 0.2 and 0.3 wt. % Cr.
EN
The potential of an indigenous bacterial strain, Chromobacterium violaceum SUK1a, isolated from surface water samples collected from Sukinda Valley in Odisha, India, has been evaluated for the first time for the bioremediation of toxic hexavalent chromium (Cr(VI)) ions. The isolate was assessed for its Cr(VI) biosorption efficiency and the various parameters affecting the biosorption process were evaluated. A maximum Cr(VI) biosorption of about 50% was obtained, and the residual chromium was in the form of less toxic Cr(III). The Gibbs free energy of biosorption was determined to be -26.3 kJ/mol, suggestive of a chemisorption process. Additionally, the Cr(VI) biosorption by the isolate followed pseudo second order kinetics. FTIR spectral studies indicated that the surface functional groups present on the bacterial isolate such as, carboxyl, hydroxyl, amino, and phosphate groups were involved in the complexation of chromium ions with the bacterial cells. X-ray photoelectron spectroscopic studies on Cr(VI) interacted bacterial cells revealed an additional peak corresponding to Cr(III) in the Cr(2p) spectra. The surface charge of the bacterial cells subsequent to interaction with Cr(VI) were less negative compared to the pristine cells, which further substantiated the bioreduction of Cr(VI) to Cr(III). The bioremediation mechanism of Cr(VI) by the bacterial isolate is delineated to be governed by both biosorption and bioreduction processes under metabolism independent conditions. The results obtained indicate that the isolate can be a promising candidate for Cr(VI) bioremediation applications.
EN
In the present research study, the efficient removal of hexavalent chromium from aqueous solutions by precipitate flotation method was investigated. The experiments were carried out with the use of ferrous sulfate as a precipitating agent for chromium and rhamnolipid bio surfactant (RL) as a precipitate collector. The effects of rhamnolipid and co-precipitate concentrations, aeration rate, solution pH, and salt addition on the chromium removal were studied using a full factorial design. The chromium removal and water recovery to foam products were analyzed as process responses. Statistical analyses showed that the effects of all factors on the chromium removal followed a non-linear trend with a peak at the middle level. After the process optimization, the maximum chromium removal of 96.75±0.3% was obtained at pH value of 8, RL/Cr ratio of 0.01, Fe/Cr ratio of 3, and aeration rate of 50 cm3/min. Addition of salt with different cationic and anionic groups negatively influenced the removal efficiency. Kinetic studies suggested that the process of chromium removal by the precipitate flotation followed the first-order process with a rate constant of about 0.018 sec-1. Given the good removal capacity and kinetics, rhamnolipid biosurfactants can be a promising environmental-friendly bio collector for the removal of chromium ions from aqueous solutions.
EN
In the paper, the permeability of polymer nanofiltration membranes was analysed. The studies were carried out for the model wastewater chromium (III) solutions at pH 4. The model wastewater chromium (III) solutions were included different concentrations of NaCl, Na2SO4, and CrCl3 . It was found that on the membrane permeability is influenced by their morphology and electrostatic properties, regardless of the composition of the feed. The negative charge of the DL membrane was limited by the polarization of the membrane and the osmotic effect. This had a beneficial effect on the permeability of the DL membrane. It positively influenced the permeability of the membrane. For the HL membrane, it does not have a surface charge under the process conditions, and the electrostatic effect is not observed. The formation of the polarization layer and the osmotic effect is limited only to a small extent by the Donnan effect. Thus, a significantly higher permeability drop for the separated salt of solutions was observed for the HL membrane, despite its looser structure. In the case of the CK membrane, it increased the polarization of the membrane, because, under the process conditions, the membrane was positively charged. This caused a reduction in membrane permeability, practically excluding its use as a nanofiltration membrane for concentrating chromium in salt solutions. The presence of small amounts of chromium in the solution containing a fixed concentration of chlorides and sulphates resulted in a slight increase in the permeability of the DL membrane to the solutions of the salts themselves. In the case of the HL membrane, this relationship was not observed. In the case of both membranes, an increase in chromium concentration caused a constant, slow decrease in permeability.
PL
W pracy przeanalizowano przepuszczalność polimerowych membran nanofiltracyjnych. Badania przeprowadzono dla modelowych roztworów ścieków chromowych o pH 4, zawierających różne stężenia NaCl, Na2SO4 oraz CrCl3 . Stwierdzono, że bez względu na skład nadawy, przepuszczalność membran zależy od ich morfologii oraz właściwości elektrostatycznych. Ujemny, w warunkach procesu, ładunek membrany DL ograniczał polaryzację membrany oraz efekt osmotyczny, co korzystnie wpływało na jej przepuszczalność. W przypadku membrany HL, w warunkach procesu nie posiada ona ładunku powierzchniowego, więc nie obserwuje się efektu elektrostatycznego. Powstawanie warstwy polaryzacyjnej i efektu osmotycznego tylko w nieznacznym stopniu jest niwelowane przez efekt Donnana. Zatem w przypadku membrany HL, mimo jej otwartej struktury, obserwowano znacznie wyższy spadek przepuszczalności dla separowanych roztworów soli. W przypadku dodatnio naładowanej w warunkach procesu membrany CK występowało zwiększenie polaryzacji membrany oraz obniżenie jej przepuszczalności. Praktycznie wykluczające użycie membrany CK jako membrany nanofiltracyjnej do zatężania chromu w roztworach soli. Obecność niewielkich ilości chromu w mieszaninie zawierającej ustalone stężenie chlorków i siarczanów powodowała nieznaczny wzrost przepuszczalności membrany DL w stosunku do roztworów samych soli. W przypadku membrany HL takiej zależności nie obserwowano. W przypadku obu membran wzrost stężenia chromu powodował stały, powolny spadek przepuszczalności.
18
Content available remote Wpływ domieszek kilku metali na właściwości krzemianu trójwapniowego
PL
W pracy przedstawiono wyniki badań wpływu dodatków ZnO, MgO, Al2O3, Cr2O3 i 2% MgO + 2% Al2O3, odpowiadający syntetycznemu alitowi. Największą wytrzymałość miał zaczyn z C3S zawierający cynk, po 28 dniach z dodatkiem 2% ZnO; wynoszącą 101 MPa. Znacznie mniejszą wytrzymałość miały próbki z dodatkiem Al2O3, a najmniejszą miał zaczyn z C3S + 1% Cr2O3. Na drugim miejscu po cynku lokuje się "syntetyczny" alit, który zapewnia dużą wytrzymałość po 1 i 2 dniach, a taką samą jak 3% dodatek ZnO po 7 dniach. Dobrą wytrzymałość daje także dodatek 2% MgO, z wyjątkiem krótkich czasów dojrzewana. Mikrokalorymetria wykazała, że występuje dobra korelacja ciepła hydratacji z wytrzymałością, aczkolwiek nie ma korelacji okresu indukcji, który jest długi w przypadku cynku, natomiast zaczyn C3S + ZnO ma po 1 dniu dużą wytrzymałość. Badania mikrostruktury zaczynów wykazały, że cynk nie jest równomiernie rozmieszczony w kryształach krzemianu trójwapniowego, są kryształy, które w ogóle nie zawierają cynku. Spowodowało to podobne zróżnicowanie w fazie C-S-H; faza ta zawierająca cynk ma nietypową morfologię.
EN
In the paper the experimental results of the influence of ZnO, MgO, Al2O3 Cr2O3 and 2% MgO + 2%Al2O3 addition to C3S, the last one corresponding to synthetic alite, on the properties of these solid solutions are presented. The highest compressive strength had the paste of C3S + ZnO, after 28 days equal to 101 MPa. Significantly lower strength had the specimens with Al2O3 and the lowest the paste of C3S+ 1% Cr2O3. On the second place after zinc was the paste of “synthetic” alite which had the high strength after 1 and 2 days and the same as the sample of C3S + 3% ZnO after 7 days. Good strength the specimens of C3S + 2% MgO are also assuring, with exception of the short period of curing. The microcalorimetry had shown the good correlation of the heat of hydration with strength, however, there was no correlation of the induction period time with early strength of the paste from C3S + ZnO. Simultaneously the observation of the pastes microstructure had shown that zinc is not uniformly distributed among the tricalcium silicate crystals; there are particles which do not contains zinc. The similar differentiation of C-S-H phase was observed; this phase containing zinc has the untypical morphology.
EN
High chromium (Cr) toxicity has turned into a serious environmental concern. Cr contaminated agronomic soils negatively affect the growth and yield of crops. Current research was conducted to enhance the phytoextraction potential of maize by using Burkholderia vietnamiensis and citric acid (CA). Plants were subjected to three concentrations of Cr (0.86, 350, and 500 ppm). A pot experiment was conducted under greenhouse conditions with completely randomized design (CRD). After 72 days of experiment, plants were harvested to analyze the morphological and biochemical attributes of soil, bacteria and plant. Results revealed that plant fresh, dry biomass, root, shoot length and chlorophyll contents significantly increased by 56%, 50%, 58%, 78% and 60%, respectively, at 500 ppm Cr concentration in combine treatment of B. vietnamiensis and CA. Maize plants treated with both B. vietnamiensis and CA significantly increased the bioaccumulation (BA) of Cr up to 50% and translocation factor (TF) by 31%. Furthermore, superoxide dismutase (SOD), proline and peroxidase dismutase (POD) activities in leaves were markedly increased by 30%, 42% and 15%, respectively, when treated with CA. Current study reveals that exogenous co-application of B. vietnamiensis + CA enhance plant growth by alleviating heavy metal stress and accelerate the phytoextraction of Cr. Taking into account the heavy metal tolerance and accumulation capacity, Zea mays is suitable for phytoremediation of contaminated soils in combination with B. vietnamiensis and CA.
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EN
The aim of the study was to determine the content of copper, manganese and chromium in white and red wines available on Polish market. The results have been compared with similar studies of other researchers as well as with the recommendations regarding dietary intake of analysed elements. Statistical analysis showed that there was a statistically important difference in manganese and copper content between the two groups of wines.
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