| Popis: |
Lactic acid promises to be an important commodity chemical in the future as a monomer for the production of biodegradable polylactic acid. With the increase of the lactic acid demand, the need to explore alternative feedstock sources and purification processes that are inexpensive and efficient is becoming more important. This paper first reports the purification results of lactic acid from the fermentation broth with paper sludge as a cellulosic feedstock using weak anion exchanger Amberlite IRA-92. Some factors such as flow rate, sample volume loaded, pH, and column were systematically examined to improve the purity, yield and productivity in lactic acid purification. Adsorption isotherm of standard lactic acid and lactic acid in the fermentation broth by anion exchanger IRA-92 were also investigated. Results indicate that in purification process the increase of pH of the fermentation broth ranging from 5.0 to 6.0 can significantly enhance the recovery yield, purity and productivity. The decrease of flow rate and sample volume loaded can also improve the recovery yield and purity but apparently reduce the productivity. In addition, the scale-up of purification process in laboratory size has little influence on the recovery yield and purity. After optimization, the yield, purity and productivity are found to be about 82.6%, 96.2% and 1.16 g LA/(g-resin day), respectively. |
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