H+-Cu2+ ion exchange on a Cu0-KU-23 sulfocation exchanger nanocomposite in solutions with various pH values

2009 ◽  
Vol 83 (5) ◽  
pp. 813-817
Author(s):  
E. V. Zolotukhina ◽  
T. A. Kravchenko
Keyword(s):  
Ion Exchange ◽  
Ph Values ◽  
Sulfocation Exchanger

Effects of pH and uranium concentration on the removal of uranium from drinking water by ion exchange

2000 ◽  
Vol 88 (12) ◽  
Author(s):  
K. Vaaramaa ◽  
Satu Pulli ◽  
Jukka Lehto
Keyword(s):  
Drinking Water ◽  
Ion Exchange ◽  
Anion Exchange ◽  
Exchange Resin ◽  
Uranium Concentration ◽  
Anion Exchange Resin ◽  
Column Experiments ◽  
Strong Base ◽  
Ph Values ◽  
Effects Of Ph

Effects of pH in the range of 5 to 8 and uranium concentration in the range of 0.02 mg/l to 25 mg/l on the removal of uranium with a strong base anion exchange resin (SBA) and a chelating aminophosphonate resin were studied. The results of the batch and column mode experiments clearly showed that the aminophosphonate resin was an efficient exchanger for the removal of uranium at pH values close to 5 and the SBA resin at higher pH values. In the column experiments, where altogether 2000 bed volumes of drinking water simulant were processed with these exchangers, the uptake of uranium was as high as 99.8% by the aminophosphonate resin at pH 5 and 99.7% by the SBA resin at pH 8.

PURIFICATION AND PARTIAL CHARACTERIZATION OF THERMOACTINOMYCES VULGARIS AMYLASES

1967 ◽  
Vol 13 (9) ◽  
pp. 1157-1163 ◽  
Author(s):  
M. J. Kuo ◽  
P. A. Hartman
Keyword(s):  
Ion Exchange ◽  
Column Chromatography ◽  
Maximum Rate ◽  
Amylase Activity ◽  
Enzyme Preparations ◽  
Ph Values ◽  
Ion Exchange Column ◽  
Optimum Ph ◽  
Thermoactinomyces Vulgaris

An α-amylase from Thermoactinomyces vulgaris has been purified about 100-fold. Its optimum pH was between 5.9 and 7.0, and the maximum rate was achieved at 60 °C. In the absence of substrate, the enzymes were more stable at pH 5.9 than at higher or lower pH values; inactivation was rapid at pH 7.0. Temperatures of 70 °C or greater also caused rapid denaturation of the enzyme in the absence of substrate. Three major peaks of amylase activity were detected when purified enzyme preparations were passed through Sephadex G-75 columns. At least two of these amylases were interconvertible. Four or five T. vulgaris proteinases also were separated, using ion exchange column chromatography.

scholarly journals Influence of organic cations sorption on the point of zero charge of natural zeolite

2009 ◽  
Vol 63 (4) ◽  
pp. 325-330 ◽  
Author(s):  
Milan Kragovic ◽  
Aleksandra Dakovic ◽  
Sonja Milicevic ◽  
Zivko Sekulic ◽  
Slobodan Milonjic
Keyword(s):  
Ion Exchange ◽  
Natural Zeolite ◽  
Point Of Zero Charge ◽  
Organic Cations ◽  
Ammonium Ions ◽  
Inorganic Cations ◽  
Ph Values ◽  
Zero Charge ◽  
Basic Characteristics

In this paper, the results of the surface modification of natural zeolite with different amounts (2, 5 and 10 mmol M+/100g) of octadecyldimethylbenzyl ammonium ions (ODMBA) are presented. The obtained organozeolites were denoted as OZ-2, OZ-5 and OZ-10. The degree of ion exchange was followed by determination of amounts of inorganic cations released from zeolite. Results confirmed that reaction between ODMBA and starting zeolite has occurred via ion exchange mechanism. The obtained value for point of zero charge, pHpzc, of natural zeolite was 6.8?0.1, while for OZ-2, OZ-5 and OZ-10 pHpzc was 7.0?0.1. Below the pHpzc, the surfaces of materials are positive while at pH values higher than pHpzc their surfaces are negative. Compared to the pHpzc of natural zeolite, no significant differences in pHpzc was observed for all three organozeolites indicating that obtained products have similar functional groups with similar acid and basic characteristics as starting zeolite. The pHpzc was not dependent on the amount of ODMBA ions at the zeolitic surface and the value of pHpzc for all investigated sorbents is the same for all three electrolyte concentrations indicating that the pHpzc of each material is independent of the ionic strength of KNO3.

Preparation and Properties of Composite Antibacterial Agent Containing Copper and Zinc Ions

2009 ◽  
Vol 79-82 ◽  
pp. 965-968
Author(s):  
Shu Xia Ren ◽  
Hui Fang Yang ◽  
Xiu Shu Tian ◽  
Yan Fang Li
Keyword(s):  
Ion Exchange ◽  
Antibacterial Agent ◽  
Antibacterial Agents ◽  
Antibacterial Activities ◽  
Exchange Capacity ◽  
Zinc Ions ◽  
Ion Exchange Capacity ◽  
Ph Values ◽  
Ion Exchange Reaction ◽  
Copper And Zinc

The composite antibacterial agents were prepared with Medical stone containing Cu2+ and Zn2+ by liquid ion-exchange reaction. The ion exchange capacity of the as-prepared Medical stone composite antibacterial agents (MSAA) products were investigated by ICP-AES, and the antibacterial activities of the agents were tested by Bacteriastasis ratio, and the structures were characterized by XRD and SEM. The results show that the conditions of preparation, such as pH, concentrations of copper and zinc ions, reaction time and reaction temperature, have important influences on the ion exchange of MSAA. The maximum ion exchange capacity have been obtained when 0.2mol/l Cu2+ and 0.6 mol /l Zn2+ reacted with Medical stone powers in the solution with pH values of 8 for 8 hours at 50 °C. Meanwhile good antibacterial activities and safety are also gained. The reasons for causing the above results are that copper and zinc ions can enter the framework of Medical stone through ion exchanging and adsorption, and are released slowly owing to its porosity.

Isotope Effects of Uranium by Ion Exchange in the System Dowex 50 / α-Hydroxyisobutyrate

1974 ◽  
Vol 29 (3-4) ◽  
pp. 190-194 ◽  
Author(s):  
Jorma Aaltonen ◽  
Klaus G. Heumann ◽  
Pikka Pietilä
Keyword(s):  
Ion Exchange ◽  
Isotope Effect ◽  
Separation Factor ◽  
Ph Value ◽  
Isotope Effects ◽  
Uranyl Ions ◽  
Distribution Factor ◽  
Ph Values ◽  
Ion Exchange Column ◽  
Ph Range

In this investigation the isotope effect of uranium in the system Dowex 50 resin/ α- hydroxyisobutyrate solution was studied by mass spectrometry. A recycle ion exchange column was used for the separation experiments. The dependence of the isotope effect on the pH value and on the concentration of the α-hydroxyisobutyrate solution used as eluent was investigated. In the case of a 0.07 ᴍ and a 0.22 ᴍ α-hydroxyisobutyrate solution the elementary separation factor of uranium was calculated to be 1.00019 and 1.00006, respectively. In both cases an enrichment of 235U in relation to 238U was found in the solution.In addition the distribution factor of the uranyl ions in the investigated system was determined in the pH range between 2 and 6. The distribution factor depends strongly on the pH value. With increasing pH values the distribution factor decreases.The results obtained for the elementary separation factor and the distribution factor are compared with other investigations.

Studies on inorganic ion exchangers. I. Preparation, properties, and applications of ferric phosphate

1976 ◽  
Vol 54 (12) ◽  
pp. 1892-1898 ◽  
Author(s):  
J. P. Rawat ◽  
Pritam Singh Thind
Keyword(s):  
Ion Exchange ◽  
Exchange Capacity ◽  
Ferric Nitrate ◽  
Dihydrogen Phosphate ◽  
Ammonium Dihydrogen Phosphate ◽  
Ion Exchange Capacity ◽  
Ph Values ◽  
Inorganic Ion ◽  
Ferric Phosphate ◽  
Oxidation Properties

Eight samples of ferric phosphates have been prepared at different pH values under different conditions. This material shows cation exchange properties. Ferric phosphate prepared by ferric nitrate and ammonium dihydrogen phosphate at pH 1 is the most stable and shows the maximum ion exchange capacity, hence, this sample is studied in detail. The mole ratio of Fe3+:PO43− is 1:2. The ion exchange capacity depends upon temperature and hydrated radii, and these relations are discussed. Certain important separations are achieved on the ferric phosphate column. Its oxidation properties are also qualitatively investigated with some reducing agents.

scholarly journals Production of amylases by Aspergillus tamarii

1999 ◽  
Vol 30 (2) ◽  
pp. 157-162 ◽  
Author(s):  
Fabiana Guillen Moreira ◽  
Francieli Arrias de Lima ◽  
Sophia Renata Fazzano Pedrinho ◽  
Veridiana Lenartovicz ◽  
Cristina Giatti Marques de Souza ◽  
...  
Keyword(s):  
Carbon Source ◽  
Ion Exchange ◽  
Filamentous Fungus ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Aspergillus Tamarii ◽  
Ph Values ◽  
Wide Range ◽  
Initial Culture ◽  
Static Cultivation

A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both <FONT FACE="Symbol">a</FONT>-amylase and glucoamylase activities in mineral media supplemented with 1% (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42oC). Two amylases, one <FONT FACE="Symbol">a</FONT>-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50o and 60o C and were stable for more than ten hours at 55oC.

scholarly journals Uranium(VI) adsorption on surfactant modified heulandite/clinoptilolite rich tuff

2006 ◽  
Vol 71 (12) ◽  
pp. 1323-1331 ◽  
Author(s):  
Srdjan Matijasevic ◽  
Aleksandra Dakovic ◽  
Magdalena Tomasevic-Canovic ◽  
Mirjana Stojanovic ◽  
Deana Iles
Keyword(s):  
Ion Exchange ◽  
Cation Exchange ◽  
Adsorption Isotherms ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Zeolitic Tuff ◽  
Zeolite Surface ◽  
Inorganic Cations ◽  
Maximal Amount ◽  
Ph Values

The adsorption of uranium(VI) on heulandite/clinoptilolite rich zeolitic tuff modified with different amounts (2, 5 and 10 meq/100 g) of hexadecyltrimethyl ammonium (HDTMA) ion was investigated. The organozeolites were prepared by ion exchange of inorganic cations at the zeolite surface with HDTMA ions, and the three prepared samples were denoted as OA-2, OA-5 and OA-10. The maximal amount of HDTMAin the organozeolite OA-10 (10 meq/100 g) was equal to the external cation exchange capacity of the starting material. The results showed that uranium( VI) adsorption on unmodified zeolitic tuff was low (0.34 mg uranium(VI)/g adsorbent), while for the organozeolites, the adsorption increased with increasing amount of HDTMA at the zeolitic surface. The highest adsorption indexes were achieved for the organozeolite OA-10, in which all the surface inorganic cations had been replaced with HDTMA. An investigation of the adsorption of uranium(VI) ions onto organozeolite OA-10 at different pH values (3, 6 and 8) showed that the adsorption index increased with increasing amount of adsorbent in the suspension. Since uranium(VI) speciation is highly dependent on pH, from the adsorption isotherms, it can be seen that uranium(VI) adsorption on organozeolite OA-10 at pH 6 and 8 is well described by a Langmuir type of isotherm, while at pH 3, it corresponds to a Type III isotherm. .

scholarly journals Lability of Cd, Cr, Cu, Mn and Pb complexed by aquatic humic substances

2005 ◽  
Vol 30 (2) ◽  
pp. 45-51 ◽  
Author(s):  
G. R. Castro ◽  
C. C. F. Padilha ◽  
J. C. Rocha ◽  
J. P. S. Valente ◽  
A. de O. Florentino ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Metal Ions ◽  
Humic Substances ◽  
Water Samples ◽  
Metal Ion ◽  
Distribution Coefficients ◽  
Metal Exchange ◽  
Aquatic Humic Substances ◽  
Ph Values ◽  
Complexation Time

The lability of Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) complexed by humic substances (HSs) was investigated by means of ion exchange on cellulose modified with p-aminobenzoic groups (Cell-PAB), using a batch procedure. The HSs were extracted from water samples using adsorption in a column packed with XAD 8 resin. The metal-HS complexes were prepared by adding solutions containing all the aforementioned metal ions ( Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) ). The results indicated that the distribution coefficients (Kd) of Cell-PAB decreased with the presence of HSs, and that the lability of metal fractions complexed by HSs decreases in pH values > 4.0, complexation time > 10 h and HS concentration > 500 mg L-1. The metal exchange between HSs and Cell-PAB exhibited the following order of metal ion lability: Cd < Pb < Mn <FONT FACE=Symbol>@</FONT> Cr < Cu.

scholarly journals Ion-Exchange and Adsorption Properties of Titania Gels Prepared from Titanous Chloride and Hydrogen Peroxide

2005 ◽  
Vol 23 (3) ◽  
pp. 215-224 ◽  
Author(s):  
Nahed Yacoub ◽  
Adham R. Ramadan ◽  
Jehane Ragai
Keyword(s):  
Hydrogen Peroxide ◽  
Ion Exchange ◽  
Nitrogen Adsorption ◽  
Adsorption Properties ◽  
Titanium Oxides ◽  
Oxidizing Agent ◽  
Ph Values ◽  
Cation Uptake ◽  
Infrared Studies

A study was carried out of the uptake of Cu2+, Ni2+, Co2+ and Ca2+ cations by hydrous titanium oxides prepared at different pH values using titanous chloride as the starting material and hydrogen peroxide as the oxidizing agent. Characterization of the oxides was carried out by nitrogen adsorption and infrared studies. The oxides were found to be amphoteric in nature and exhibited an isoelectric point of 6.6. An attempt was made to elucidate the mechanism of cation uptake which does not entail a simple ion-exchange mechanism.

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