scholarly journals Water Transport during Ion Conduction in Anion-Exchange and Cation-Exchange Membranes

2009 ◽  
Vol 156 (7) ◽  
pp. B831 ◽  
Author(s):  
Toshiro Yamanaka ◽  
Tatsuya Takeguchi ◽  
Hiroki Takahashi ◽  
Wataru Ueda
Keyword(s):  
Cation Exchange ◽  
Anion Exchange ◽  
Water Transport ◽  
Ion Conduction

Current dependence of water transport in cation-exchange membranes

1968 ◽  
Vol 72 (4) ◽  
pp. 1253-1258 ◽  
Author(s):  
Nallanna Lakshminarayanaiah ◽  
V. Subrahmanyan
Keyword(s):  
Cation Exchange ◽  
Water Transport ◽  
Current Dependence

scholarly journals Alkali Attack on Cation-Exchange Membranes with Polyvinyl Chloride Backing and Binder: Comparison with Anion-Exchange Membranes

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 228 ◽  
Author(s):  
Shoichi Doi ◽  
Nobuya Takumi ◽  
Yuriko Kakihana ◽  
Mitsuru Higa
Keyword(s):  
Cation Exchange ◽  
Anion Exchange ◽  
Polyvinyl Chloride ◽  
Chemical Structure ◽  
Immersion Test ◽  
Ion Concentration ◽  
Membrane Properties ◽  
Anion Exchange Membranes ◽  
Alkali Solutions ◽  
Exchange Membrane

Systematic alkali immersion tests of cation-exchange membranes (CEM) with polyvinyl chloride (PVC) as their backing and binder were conducted to compare that of an Anion-exchange membrane (AEM) with the same PVC materials to investigate the mechanism of dehydrochlorination. In the immersion tests, originally colorless and transparent AEM turned violet, and chemical structure analysis showed that polyene was produced by the dehydrochlorination reaction. However, the CEM did not change in color, chemical structure or membrane properties during the test with less than 1M alkali solutions. According to the Donnan equilibrium theory and the experiments using CEM and AEM, the hydroxide ion concentration in the CEM was much lower than that in the AEM under the same conditions. However, when the alkali immersion test was performed using the CEM under more severe conditions (6 M for 168 h at 40 °C), there was a slight change in the color and chemical structure of the CEM, clearly indicating that not only AEMs, but also CEMs with PVC matrixes were deteriorated by alkali, depending on the conditions.

Chemical fertility of krasnozems - a review

Soil Research ◽  
1994 ◽  
Vol 32 (5) ◽  
pp. 1015
Author(s):  
PW Moody
Keyword(s):  
Organic Matter ◽  
Cation Exchange ◽  
Anion Exchange ◽  
Cation Exchange Capacity ◽  
Clay Fraction ◽  
Exchange Capacity ◽  
Published Data ◽  
Total N ◽  
Eastern Australia ◽  
Ph Buffer

Krasnozems (Ferrosols) characteristically have high contents of citrate-dithionite extractable Fe and moderate to high contents of clay throughout the profile. They typically have low cation exchange capacity (2-20 cmolc kg-1), high P sorbing ability, and a significant anion exchange capacity at depth. The chemistry of krasnozems is dominated by the variable charge characteristics of the organic matter and the oxy-hydroxides of Fe and Al which occur in the predominantly kaolinitic clay fraction. The effects of surface charge characteristics, organic matter, and extractable iron and aluminium on the cation and anion exchange capacities, P sorbing abilities and pH buffer capacities of Australian krasnozems are reviewed. A selection of reports of nutrient deficiencies and toxicities in these soils is presented and briefly discussed. Published data on the chemical composition of the soil solutions of krasnozems are reviewed. Data from a suite of paired (undeveloped and developed) krasnozem profiles from eastern Australia indicate that exchangeable Ca and Mg, effective cation exchange capacity (ECEC), pH buffer capacity (pHBC) and total N decrease significantly (P < 0.05) in the A horizon following development, while exchangeable K, ECEC and pHBC decrease (P < 0-05) in the B horizon. The decreases in the A horizon are shown to be a direct consequence of the decline in organic matter which occurs following development. Because of the crucial role that organic matter plays in the chemical fertility of krasnozems, they are less likely to maintain their fertility under exploitative conditions than other productive clay soils such as Vertosols. It is concluded that the sustainable use of krasnozems will depend on maintenance or enhancement of organic matter levels, maintenance of surface and subsoil pH by regular application of amendments, minimization of erosion, and replacement of nutrients removed in harvested products.

Exchangeable Cations and Picloram Sorption by Soil and Model Adsorbents

Weed Science ◽  
1979 ◽  
Vol 27 (3) ◽  
pp. 257-262 ◽  
Author(s):  
J. S. Arnold ◽  
W. J. Farmer
Keyword(s):  
Cation Exchange ◽  
Anion Exchange ◽  
Equilibrium Solution ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Cation Exchange Resin ◽  
Adsorptive Capacity ◽  
Solution Ph ◽  
Exchange Complex ◽  
Polyvalent Cations

The adsorption of picloram (4-amino-3,5,6-trichloropicolinic acid) was determined on an Aiken silt loam, on three cation exchange resins and on a single anion exchange resin. Adsorption data were evaluated using parameters in the Freundlich equation and their dependance upon cationic composition of the exchange complex, the ionic composition of the equilibrium solution, and the equilibrium solution pH. For the Aiken soil saturated with metallic cations the order of decreasing picloram adsorptive capacity was Fe+3= Cu+2> Al+3> Zn+2> Ca+2> native soil. Increases in adsorption compared to the native Aiken soil could be explained on the basis of decreases in the equilibrium solution pH except for Fe+3, Zn+2, and especially the Cu+2treatments. The adsorptive capacity of the Aiken soil was altered by the addition of several salts simulating addition of fertilizer salts. The Cu+2and Zn+2salts were the only treatments showing increased adsorption which could not be explained readily by pH changes. KH2PO4and NH2CONH2(urea) reduced picloram adsorption. Dowex 50-1 × 4, a strongly acidic cation exchange resin, showed increased picloram adsorptive capacity in the order Cu+2> Al+3> Ca+2> Zn+2= H+. Cellex CM, a weakly acidic cellulose exchanger had increased adsorptive capacities in the order of Cu+2> Ca+2> Al+3> Na+> Fe+3> Zn+2. Picloram adsorption by an anion exchange resin at pH 6.1 was nearly 100%. These results suggest that complex formation of picloram with polyvalent cations on the exchange complex is likely especially for Cu+2and to a lesser extent Fe+3and Zn+2. In soils such complex reactions would most probably involve organic matter, polyvalent cations, and picloram. The formation of chelate ring species is proposed.

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