Evaluation of Nanofiltration Membranes for Pure Lactic Acid Permeability

Abstract

Lactic acid (LA) is an organic acid produced by fermentation or chemical synthesis. It plays a crucial role in the pharmaceutical, food and plastic industries. In the fermentation of, for example, grass silage, LA and different compounds are produced. To purify lactic acid, researchers have tried to investigate membrane technology to achieve a high yield of lactic acid permeance. This study tested four commercially available nanofiltration membranes (NF270, MPF-36, Toray NF, and Alfa Laval NF). Nanofiltration experiments were performed to investigate the rejection levels of lactic acid from a binary solution by using distinct molecular weight cut off membranes. All of the experiments were conducted with a lab-scale cross-flow membrane unit. Different operating conditions (pH, temperature) were studied for each membrane; the optimal process condition was found at 25 °C and pH 2.8. With higher temperatures and pH, an increase in LA rejection was observed. The MPF-36 membrane shows the lowest lactic acid rejection yield of 7%, while NF270 has the highest rejection yield of 71% at 25 °C and pH 2.8. These results will be helpful in the future to understand both the interaction of lactic acid permeance through nanofiltration membranes and process scale-up.

The Application of the Nanofiltration Membrane NF270 for Separation of Fermentation Broths

“…It is composed of the active layer made from semiaromatic piperazine-based PA and the support layers from polysulfone (PS) and nonwoven polyester (PET) (Figure 4). Table 2 summarizes the physicochemical characteristics of the membrane, as given by the manufacturer, and several studies reported in the literature [31,33,[78][79][80][81][82][83][84][85][86]. During the investigation performed in the present study, the membrane surface was negatively charged since the pH of the fermentation broths (equal to 7) was higher than the isoelectric point of the membrane (equal to 4).…”

“…(i) The highest rejection of succinic acid is related to the fact that it is a diprotic acid, hence, its separation was based on much stronger electrostatic interactions than in Lactic acid may be produced in two ways: biotechnological process and chemical synthesis [16,79]. However, according to [100], 90% of all lactic acid produced worldwide is derived via fermentation processes and the cost of its separation from fermentation broths can reach 50% of the total process costs.…”

Progress in the Degradability of Biodegradable Film Materials for Packaging

“…Polylactic acid (PLA) is a type of degradable polymer material with lactic acid as raw material [ 166 , 167 ], which is renewable and has the characteristics of non-toxicity, non-irritation, good biocompatibility, processability, excellent mechanical properties, complete biodegradability and environmental friendliness [ 168 , 169 ], and is considered as the main alternative to petroleum-based plastics [ 170 ].…”

The Performance of Microfiltration Process for Purifying Lactic Acid in the Fermented Broth of Kitchen Waste

“…Even in 2010, the U.S. Department of Energy issued a report that listed LA as a potential building block for the future [ 3 ]. There are two main production methods for LA, chemical synthesis, and biological fermentation [ 1 , 4 , 5 ]. Compared with chemical synthesis, biological fermentation can use low-cost biomass waste, such as kitchen waste [ 6 ], straw [ 7 ], and sludge [ 8 ] as substrates for microbial LA fermentation, which is more environmentally friendly, has low energy consumption, and can produce LA with higher optical purity [ 9 , 10 ].…”