CRM Membrane for L-Lactic Production

Lactic acid is chiral, consisting of two enantiomers. One is known as L-(+)-lactic acid and the other, its mirror image, is D-(−)-lactic acid.  A mixture of the two in equal amounts is called DL-lactic acid, or racemic lactic acid.In industry, lactic acid fermentation is performed by lactic acid bacteria, which convert simple carbohydrates such as glucose, sucrose, or galactose to lactic acid.

As a starting material for industrial production of lactic acid, almost any carbohydrate source containing C5 and C6 sugars can be used. Pure sucrose, glucose from starch, raw sugar, and beet juice are frequently used. Lactic acid producing bacteria can be divided in two classes: homofermentative bacteria like Lactobacillus casei and Lactococcus lactis, producing two moles of lactate from one mole of glucose, and heterofermentative species producing one mole of lactate from one mole of glucose as well as carbon dioxide and acetic acid/ethanol.

L-Lactic acid can be used to produce poly-lactic (PLA). In recent year, PLA has become a popular material due to it being economically produced from renewable resources. In 2010, PLA had the second highest consumption volume of any bioplastic of the world. Its widespread application has been hindered by numerous physical and processing shortcomings. PLA is the most widely used plastic filament material in 3D printing.The monomer is typically made from fermented plant starch such as from corn, cassava, sugarcane or sugar beet pulp.

Several industrial routes afford usable (i.e. high molecular weight) PLA. Two main monomers are used: lactic acid, and the cyclic di-ester, lactide. The most common route to PLA is the ring-opening polymerization of lactide with various metal catalysts (typically tin octoate) in solution or as a suspension. The metal-catalyzed reaction tends to cause racemization of the PLA, reducing its stereoregularity compared to the starting material (usually corn starch).
 

Integrated Ceramic membrane and nanofiltration  membrane technology can be successfully applied for broth clarification and lactic decoloration. The technology can greatly simplify the downstream process, reduce production cost, increase product cost and reduce waste discharge.