Sinan Yapici
Inonu University, Turkey
Title: Effect of initial salt concentration on acid and base production from NH4Cl - NaCl solution by bipolar membrane electrodialysis
Biography
Biography: Sinan Yapici
Abstract
In this study, a four-compartment bipolar membrane electrodialysis process was applied to produce ammonium hydroxide, sodium hydroxide and hydrochloric acid from an aqueous salt solution consisted of ammonium chloride and sodium chloride mixture. One of the most effective parameters in this sort of systems is the initial salt concentration. The purpose of this work is to study the effects of the initial ammonium chloride and sodium chloride concentration on the produced amount of hydrochloric acid, ammonium hydroxide and sodium hydroxide, the product-based salt conversion, the ion mass fluxes transferred through the membranes. The ratio of NH4CI/NaCI was kept constant and the initial values of NH4CI/NaCI ranged between 10/5 and 120/60 g/L. The other working conditions was maintained constant at the temperature of 25oC, electrolyte flow rates of 10 L/h, at the potential difference of 10 V and the initial acid and base concentration of 0.4 M. The experiments showed that the mass flux of the ions for the initial salt concentrations up to 40/20 (NH4CI/NaCI) g/L, first increased, and then started to decrease after reaching at a maximum. Above this value, the mass flux values decreased with time, having almost a constant value for a while and then continued to decrease again. These behaviour shows that the initial salt concentration has an important effect on the mass flux of ions, that is, the rate of the process. The conversion ratios up to a value of %70 was attained at the lowest initial salt concentration in a quite short processing time in about 100 minutes. As the salt concentration increased, the conversion reduced down below %50 for the highest salt concentration in a longer period of 480 minutes, showing the initial salt concentration has an important effect on conversion ratio. The consumed energy decreased with increasing initial salt concentration, from 2.22 to1.18 kWatt∙h/kg converted salt.
Acknowledgement: Thanks to TUBITAK for its support for this work with the project no: 115Y342
Figure 1. Change of conversion with initial salt concentration.