Nikkei. Tohoku Electric Power Co. has developed a process to convert glycerin, a major byproduct of biodiesel fuel production, into lactic acid for use in making polylactic acid (PLA), a type of biodegradable plastic.
While researching production of large quantities of acetic acid from rice hulls, the firm’s R&D center discovered that glycerin could be converted into lactic acid. It then conducted basic research on conditions to facilitate such conversion and found that stable conversion to lactic acid could be achieved by mixing the glycerin with alkaline water and raising the temperature to 300°C and the pressure to 12 megapascals.
Tohoku Electric has reached an agreement with Hitachi Zosen Corp. to develop a lactic acid production system that increases reaction efficiency and can convert large quantities of glycerin into lactic acid.
The conventional process for polylactic acid production starts with bacterial fermentation of sugar from corn, sugarcane or other renewable source to produce lactic acid. The lactic acid is then converted into lactide (two lactic acid molecules are converted into one lactide molecule). After purification through vacuum distillation, the lactide undergoes a solvent-free melt process that causes the ring-shaped lactide polymers to open and join end-to-end to form long chain polymers.