Organic Acids Recovery by Nanofiltration

Nanofiltration (NF) is a type of pressure-driven membrane that separates solute based on the size as well as charge exclusion. A negatively charged membrane is used to repel anionic organic acid such as lactic acid, acetic acid, citric acid, amino acid, formic acid, and oxalic acid while allowing the uncharged solutes like sugar to pass through (Fig. 1). However, if the membrane is positively charged, the adverse phenomenon will be observed. NF for organic acid recovery is always regarded as a green biorefinery method due to its low energy consumption and unique separation properties, for example, nanofiltrations can be used as a method to separate lactic acid from the nutrients, salt, and unreacted carbon in fermentation broth; thus it combines production and purification of the organic acid in a single operation unit. Commercial nanofiltration such as Osmonics (DK, DL, HL), Hydranautics (HT), Filmtec (FT), Sepro (NF2, NF3, NF20), and Koch (KO) with molecular weight cutoff of 100–350...