LAUSR

Abstract Bipolar membrane electrodialysis (BMED) has already been described for the preparation of quaternary ammonium hydroxide. However, compared to quaternary ammonium hydroxide, di-quaternary ammonium hydroxide has raised great interest due to its high thermal stability and good oriented performance. In order to synthesize N , N -hexamethylenebis(trimethyl ammonium hydroxide) (HM(OH) 2 ) by EDBM, experiments designed by response surface methodology were carried out on the basis of single-factor experiments. The factors include current density, feed concentration and flow ratio of each compartment (feed compartment: base compartment: acid compartment: buffer compartment). The relationship between current efficiency and the above-mentioned three factors was quantitatively described by a multivariate regression model. According to the results, the feed concentration was the most significant factor and the optimum conditions were as follows: the current efficiency was up to 76.2% (the hydroxide conversion was over 98.6%), with a current density of 13.15 mA·cm − 2 , a feed concentration of 0.27 mol·L − 1 and a flow ratio of 20 L·h − 1 :26 L·h − 1 :20 L·h − 1 :20 L·h − 1 for feed compartment, base compartment, acid compartment, and intermediate compartment, respectively. This study demonstrates the optimized parameters of manufacturing HM(OH) 2 by direct splitting its halide for industrial application.