Calculation of the Helfferich Number to Identify the Rate-Controlling Step of Ion Exchange for a Batch Process

1995 ◽  
Vol 34 (8) ◽  
pp. 2584-2587 ◽  
Author(s):  
K. Bunzl
2012 ◽  
Vol 66 (12) ◽  
Author(s):  
Jiří Kaláb ◽  
Zdeněk Palatý

AbstractBatch electrodialysis of aqueous solutions of oxalic acid was investigated using a laboratory electrodialyzer ED-Z mini equipped with ion-exchange membranes Ralex-AMH-PES and Ralex-CMHPES (Mega, Stráž pod Ralskem, Czech Republic). The paper presents a mathematical model which enables to predict changes in the oxalic acid concentrations in the diluate and concentrate compartments during the electrodialysis process under various conditions specified by combinations of the initial acid concentrations with current densities. The calculation proved a good agreement between the developed model and the experimental results.


2013 ◽  
Vol 11 (1) ◽  
pp. 385-392
Author(s):  
Marcionila O. Ferreira ◽  
Elisa M.B.D. Sousa ◽  
Camila G. Pereira

Abstract The objective of this study was to purify glycerine obtained from the transesterification of cottonseed oil, using ion exchange resins. The batch process used strong cation, weak anion and a mixture of its resins. The purified glycerine was characterized as to metal content, colour and glycerol content. The experiments were conducted using the resins individually and in series. In the experiments in series, there was a constant decrease in conductivity. Analyses without the use of charcoal showed that conductivity behaved similarly to that of treatment with charcoal. For conductivity tests using activated charcoal and individual resins, the mixed resin produced the best result when compared to commercial glycerine.Considering the analysis made with activated carbon, when the glycerine solution was treated with individual resins, it was observed that the conditions established for treatment with 10 g of resin, 5 hours of contact with each resin and 50 mL of glycerine, its conductivity decreased to the cation exchange resin, increased to anionic resin and had a variable value with respect to the mixed resin. In serial processing, there was a steady decrease in the conductivity of the glycerine solution. The content of glycerol, after the solution had been passed through activated charcoal, 56% of the compound was recovered. It was also observed that the mixed resin retained a lower amount of glycerol. It can be concluded that ion exchange resins were efficient in treating the glycerine solution in all the tests, since there was little glycerol retention and high undesirable compound retention.


Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.


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