Recovery of perilla anthocyanins from spent brine by diafiltration and electrodialysis

Abstract

Separation of perilla anthocyanins from sodium chloride in spent pickling brine was investigated using diafiltration (DF) and electrodialysis (ED). An ultrafiltration (UF) membrane of nominal molecular weight cut-off of 2000 daltons was used for DF because of its satisfactory permselectivity for separating the pigment and salt. At an added-water volume to original feed ratio of 4, constant-volume diafiltration (CVDF) removed 95% of the salt, and sequential dilution diafiltration (SDDF) removed 87% of the salt from the brine. Both processes recovered more than 90% of the anthocyanins. During ED, increasing current density increased the salt removal rate, but also increased the power consumption and decreased the current efficiency. The ED process could remove 90% of the sodium chloride while recovering 86% of the anthocyanins from the spent brine.