Electrodialysis Method

There are several companies and groups that are developing bio-based succinic acid production for commercial use. The Showa group possesses a unique technology for purification of succinic acid from fermentation broth. This is the fractional crystallization method starting from sodium succinate. The yield by this method is around 70%, but we can recycle the residual solution so that we can minimize the loss of the product. We also compared the cost-effectiveness of this method with the bipolar electrodialysis method. The cost of our purification process seemed to be about half (our internal data). 

The addition of small amounts of amines and ammonium salts makes it possible to increase selectivities and current efficiencies to about 90 % over a prolonged period, even at Pb cathodes516 517). Recent Japanese applications claim special process modifications, such as the reactivation of the cathodes by pole reversal in alkaline electrolytes 518), special temperature programs during electrolysis519), and working up the discharged electrolysis solution by electrodialysis methods 520). The use of porous cathodes 521) was also proposed. 

The efficiency of producing hydrogen through a sulphur-iodine process is very sensitive to the HI decomposition process. In Korea, an electrodialysis method was selected to concentrate HI in the solution. The current status of HI concentration and decomposition characteristics with electrodialysis, distillation and HI decomposition catalyst is presented. Another sensitive item of iodine content is also briefly described. A future plan on how to demonstrate a lab-scale SI closed loop is also presented with key issues. 

As early as 1915, Schiwerin and coworkers made commercial silica sol by using an electrodialysis method. The production of silica sol has progressed in the past 30 years. It was recently reported that the concentration of SiC>2 in silica sol solution has reached as high as 60%.[11] The concentration of [Si02] in the commercial products Ludox-AS-40 and -HS-40 used in the synthesis of zeolites is about 40%. 

In this respect, the present work discusses the polymer electrolyte membrane electrodialysis method to concentrate the HI over HIx solution. For this purpose, we prepared Hix solution with subazeotrope composition (HI I2 H2O = 1.0 0.5 5.8) and the polymer electrolyte membrane electrodialysis was investigated using galvanodynamic and galvanostatic polarisation method. 

Although the dialysis method, which involves the reaction of dilute water glass with an acid followed by dialytic removal of the sodium salt as the formed electrolyte, was proposed in 1861, it was never applied on an industrial basis. Furthermore, the electrodialysis method was attempted in various ways as a method for electrically removing sodium salt from water glass. But, unlike the last three methods mentioned, it did not reach the level of practical application. 

Lipkind et al (Experimental Plant of the All-Union Oil Processing Research Institute, Gorky Research Institute of the Chemical Industry, Kemerovo) set up the industrial production of sols made from silicic acid by the electrodialysis method (70). The capacity of the experimental pilot plant is 100 L of sol per hour. 

The electrodialysis method uses tanks lined with an insulating layer. From 5 to 30 properly spaced counterelectrodes are surrounded by membranes (Figure 2), which separate the coating bath from the counterelectrode by means of a membrane permeable to the solubilizer Y. A plumbing system flushes the solubilizer out of the counterelectrode compartment (Figure 2). 

Many attempts to prepare ion exchange membranes having permselectivity for specific ions and to find electrodialysis methods to achieve such a purpose have been made. In this chapter, studies on the modification of ion exchange membranes and electrodialysis methods to permeate specific ions through the membrane, mainly in electrodialysis, are explained. 

Y. Mizutani, R. Yamane and T. Sata, Electrodialysis method to permeate lower valent cations selectively, Jpn. Pat., JP 46-23607 (examined application), US Pat. 3,510,417, 3,510,418, Br. Pat, 1,238,656 F. Hanada, N. Ohmura Y. Kagiyama and Y. Mizutani, Monovalent cation permselective membrane, Nippon Kaisui Gakkaishi Bull. Soc. Sea Water Sci), 1990, 44, 116. 

Y. Mizutani, R. Yamane, T. Sata and R. Izuo, Cation exchange membrane to selectively permeate hydrogen ions and electrodialysis method to selectively permeate hydrogen ions, Jpn. Pat. JP 47-3801 (examined application) Z. Ogumi, Y. Uchimoto, M. Tsujikawa, K. Yasuda and Z. Takehara, Modification of ion exchange membrane surface by plasma process. Part 3. Interfacial resistance of monovalent permselective membrane from Nafion, Bull. Chem. Soc. Jpn., 1990, 63, 2150. 

Figure 6.13 Principle of continuous electrodialysis method with partial circulation.

The applicability of the electrodialysis method was verified on a pilot scale [39]. The operating costs were found to be substantially lower than with the common process using ion-exchange and detoxification units. Considerable savings are due to the fact that almost no chemicals are consumed, and the expenses for maintenance and salaries are much lower than with the common process. 

Considerable successes in the separation of amino acids by electrodialysis methods were achieved by Ryazanov and co-workers [52,53]. 

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