Temat: separation selectivity - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Wpływ modyfikatora fazy ruchomej na selektywność rozdzielenia w odwróconym układzie faz wysokosprawnej chromatografii cieczowej
Influence of mobile phase modifier on separation selectivity in reversed phase high performance liquid chromatography
Autorzy:: Misiołek, B.
Klimek-Turek, A.
Dzido, T. H.
Powiązania:: https://bibliotekanauki.pl/articles/172139.pdf
Data publikacji:: 2013
Wydawca:: Polskie Towarzystwo Chemiczne
Tematy:: retencja substancji
selektywność rozdzielenia
wpływ modyfikatora na selektywność
wysokosprawna chromatografia cieczowa z odwróconym układem faz
HPLC
RP-HPLC
retention of solutes
separation selectivity
effect of modifier on selectivity
reversed-phase high-performance liquid chromatography
RP HPLC
Opis:: High performance liquid chromatography (HPLC) is an instrumental analytical technique, which is widely used for a separation and determination of a mixture of components in many samples (e.g. of biomedical, pharmaceutical, food, and environmental origin). Despite several decades of the development of this technique, some aspects of the chromatographic process are still open to questions. This is particularly related to mechanisms of retention and selectivity of a separation. Improvement of the separation selectivity can be achieved by a change of the stationary phase type and qualitative and/or quantitative composition of the mobile phase. The replacement of the stationary phase does not ensure a smooth change of selectivity and retention, however, it generates additional costs of analysis. Therefore, the optimal conditions of chromatographic separation can be easily obtained by the change of a composition of the mobile phase, i.e. the type and/or concentration of its modifier (organic solvent). This paper presents an overview of approaches to explanation and interpretation of an influence of mobile phase composition on the retention and separation selectivity in liquid chromatography systems with particular emphasis on modifier type of eluent in the reversed phase high performance liquid chromatography (RP HPLC).
Źródło:: Wiadomości Chemiczne; 2013, 67, 1-2; 133-159
0043-5104
2300-0295
Pojawia się w:: Wiadomości Chemiczne
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Selective chromium III/VI separation in polymer inclusion membrane system
Autorzy:: Rajewski, J.
Religa, P.
Wojasiński, M.
Gierycz, P.
Powiązania:: https://bibliotekanauki.pl/articles/115544.pdf
Data publikacji:: 2014
Wydawca:: Fundacja na Rzecz Młodych Naukowców
Tematy:: chromium separation
selectivity
D2EHPA
PIM
Opis:: Analyze of chromium(III) transport process from mixtures of Cr(III)/Cr(VI) ions with polymer inclusion membrane (PIM) system have been done. Di(2-ethylhexyl) phosphoric acid (D2EHPA) have been used as a carrier. It was found that the transport efficiency in PIM is dependent on the carrier concentration in the membrane. It was found that there is an optimal range of carrier concentration in the membrane, which ensures rapid and efficient transport. In studied system optimal D2EHPA concentration was in range between 0,9- 1,5 mol/dm3. Membrane worked as selective barrier for Cr(VI) ions. However increase of Cr(VI) concentration above 0,0005 mol/dm3 negatively influenced Cr(III) transport. It was caused by degradation of the polymer inclusion membrane made of cellulose triacetate (CTA) . Strongly oxidizing Cr(VI) ions can damage polymer inclusion membrane with CTA matrix. The chemical attack of strongly oxidant Cr(VI) ions could lead either to hydrolysis of the pendant acetyl group or to oxidation of polymer backbone leading to chain scission. Moreover, oxidation is accelerated at high concentration of Cr(VI) ions. The membrane containing D2EHPA as a carrier can be recommended for selective separation of Cr(III) ions only from diluted Cr(VI)/Cr(III) mixtures. However the polymer inclusion membrane need a change the polymer matrix.
Źródło:: Challenges of Modern Technology; 2014, 5, 1; 15-19
2082-2863
2353-4419
Pojawia się w:: Challenges of Modern Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Wpływ jakości nadawy na jakość produktów wzbogacania ocenianych za pomocą wykresu Fuerstenaua dla przypadku symetrycznej krzywej separacji
Influence of feed quality on quality of separation products evaluated by means of the fuerstenau plot for symmetrical separation curves
Autorzy:: Duchnowska, M.
Drzymała, J.
Powiązania:: https://bibliotekanauki.pl/articles/216515.pdf
Data publikacji:: 2011
Wydawca:: Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:: wzbogacanie
separacja
selektywność
flotacja
upgrading
separation
selectivity
flotation
Opis:: Jeżeli wyniki wzbogacania dają się opisać na tzw. wykresie Fuerstenaua krzywą opisywaną równaniem matematycznym z jednym dopasowywanym parametrem, wtedy parametr ten może być wykorzystany jako wskaźnik selektywności wzbogacania. Jeżeli równanie to ma postać [...] (gdzie \epsilon oznacza uzysk składnika użytecznego w koncentracie, a [...] uzysk nieużytecznego składnika w odpadzie), wtedy przy stałej selektywności wzbogacania (stałe a) wzrost zawartości składnika użytecznego w nadawie \alfa powoduje, że następuje wzrost ilości składnika użytecznego zarówno w koncentracie \beta jak i w odpadzie \theta, przy czym przy stałym uzysku składnika użytecznego w koncentracie \epsilon stosunek \theta do \beta rośnie liniowo z \alfa. Oznacza to, że przy stałej selektywności procesu separacji a oraz stałym uzysku składnika użytecznego w koncentracie \epsilon wzrost zawartości składnika użytecznego w nadawie \alfa powoduje większy wzrost ilości składnika użytecznego w odpadzie niż w koncentracie.
When mineral processing separation results, for either constant or varying quality of the feed, can be approximated on the so-called Fuerstenau upgrading plots with the same one-fitting parameter a, then this parameter can be used as a selectivity indicator. If the equation has a form [...], where [...] stands for recovery of non-useful component in tailing while\ksi is the recovery of useful component in the concentrate, then at the same selectivity of upgrading (constant a) the increase of the useful component in the feed \alfa results in an increased amount of this component in both concentrate \beta and tailing [...] while the ratio of [...] to \beta is linearly dependent on \alfa when \epsilon is constant. Thus, at a constant selectivity a and constant \epsilon an increase in \alfa leads to a greater increase of the considered component in the tailing \theta than in the concentrate \beta.
Źródło:: Gospodarka Surowcami Mineralnymi; 2011, 27, 2; 33-41
0860-0953
Pojawia się w:: Gospodarka Surowcami Mineralnymi
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Interrelation of the fuerstenau upgrading curve parameters with kinetics of separation
Autorzy:: Bakalarz, A.
Drzymala, J.
Powiązania:: https://bibliotekanauki.pl/articles/109709.pdf
Data publikacji:: 2013
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: separation
upgrading
kinetics
Fuerstenau curve
beneficiation
recovery
selectivity
Opis:: It was shown in the paper that kinetic equations relating recoveries of two components in separation products and time, when combined together to eliminate the time parameter, provide mathematical equations which relate recoveries of the two considered components in concentrate. The obtained one-adjustable-parameter type equations are very useful for approximation of the separation results plotted as the so-called Fuerstenau upgrading curves. Most empirical mathematical formulas presently used for the Fuerstenau plots were derived using various kinetic equations while some are still awaiting for their kinetic derivation.
Źródło:: Physicochemical Problems of Mineral Processing; 2013, 49, 2; 443-451
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: A new approach in separation process evaluation. Efficiency ratio and upgrading curves
Autorzy:: Irannajad, M.
Nuri, O. S.
Allahkarami, E.
Powiązania:: https://bibliotekanauki.pl/articles/110189.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: separation efficiency
mineral processing
selectivity index
process evaluation
efficiency ratio
operation efficiency
Separation Process
Opis:: In mineral processing separation efficiency (SE), operation efficiency (OE), selectivity index (SI) and other indices have been used to evaluate the separation process. Up to now, no study has been conducted on the relationship between the SE, OE and SI indices. In this research, two upgrading curves are proposed based on the above indices for process and selectivity evaluation. The first upgrading curve is based on recovery R, SE, and OE as a function of concentrate grade. This curve has three background lines, including no upgrading line, ideal upgrading line and the ideal mixing line. The proposed upgrading curve is applicable not only for process evaluation by specification of OE and SE, but also for selectivity evaluation with the lowest difference between SE and OE. The curve showed that the recovery value is always greater than the SE and OE values. The parameters of OE, SE and R were used for plotting the upgrading curve as a function of concentrate grade taking into consideration all of them at a time. A new selectivity indicator, namely Efficiency Ratio (ER) as the selectivity parameter, is proposed as the ratio of OE to SE. The ER values fluctuate between 1 and . It can be presented as a function of concentrate and tailing grades (ER = [c(1-t)]/[1(c-t)]). The results showed that ER is insensitive to the feed grade and has the inverse relationship with SI. To measure the separation selectivity, another upgrading curve is proposed based on ER and SI parameters. This curve is divided into seven separation classes for evaluation the class of a separation process from ideal class to no separation one. The results of this research can be useful for separation process evaluation.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 3; 847-857
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Evaluation of flotation reagents by normalization procedures
Autorzy:: Drzymala, J.
Powiązania:: https://bibliotekanauki.pl/articles/109804.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: flotation
separation
foam
froth
frother
selectivity
efficiency
normalization
generic reagents
selective reagents
internal parameter
external parameter
Opis:: Froth flotation is a dynamic multiphase process in which particulate matter is separated with the help of chemical reagents by gas bubbles immersed in water. The original flotation results are usually presented in the form of kinetic curves relating recovered particulate matter mass (yield ) or mass of a selected component (recovery ), both shortly denoted as y, versus process time t at different concentrations c (g/dm3) of the applied reagents. The kinetic curves can be modified into three: incentive (maximum yield or recovery ymax vs c), limits (ymax vs kinetic constant k or specific rate) and half-life of flotation (t1/2 vs c) curves. The original and modified curves can be normalized by taking into account either an external parameter such as molecular mass (MW), critical coalesce concentration (CCC), critical concentration at the minimum bubble velocity (CMV), dynamic foaming index (DFI), and many other parameters or an internal parameter such as time, concentration needed to achieve certain yield, recovery (y) or kinetic constant. Normalization leads to new flotation curves and provides additional useful information about flotation performance. Normalization can be fully effective, partial or ineffective. Normalization of the original flotation kinetic curves usually is ineffective. Also, normalization of the incentive curve with external parameters such as frother molecular mass, which changes reagent concentration from c (g/dm3) to C (mol/dm3), is also ineffective. Partially effective are normalizations with other external parameters such as CCC and CMV, usually within the same class of regents, for instance alcohols. Only DFI seems to be a universal external normalization parameter for flotation results because it provides fully effective normalization and thus predicts the flotation results. Limited data on DFI restrict a full verification of this hypothesis. Normalization of the modified flotation curves with internal parameters such as k50 (value of 1st order kinetic constant when recovery or yield is 50% after a given flotation time), Ct1/2 (frother concentration in mol/dm3 at which the flotation half-life has an arbitrarily chosen value) and cy75 (frother concentration in g/dm3 at which recovery or yield is 75% after a given flotation time) is a good base for practical classification of flotation reagents.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 1; 182-192
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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