Developments in the separation and recovery of penicillin G using hollow-fiber membrane contactors

The separation and recovery of pharmaceuticals such as penicillin G from fermentation media is very important. For this purpose, the research for an efficient, cost-effective and environmentally-friendly process continued over the last two decades. Various solvents including kerosene, butyl acetate, tributyl phosphate (TBP), octanol and their mixtures have shown to have the potential but they have the disadvantages of being toxic and expensive. Recently, non-traditional solvents like vegetable oils have been examined as they can overcome some of the above-mentioned disadvantages. In this chapter, results of research are presented for various organic solvents including non-traditional ones like vegetable oils for the separation of penicillin G using physical and reactive extractions. the first step of the investigation, the effects of organic solvents on apparent distribution of penicillin G either from a single-component solution or from a synthetic media are determined. Then the effects of the addition of an ionic "carrier", such as Amberlite-LA- in the solvent on the enhancement of the distribution factor and on the degree of extraction are examined. The carrier-solvent systems have shown to have considerable improvement in the percentages of separation of penicillin G. As a demonstration of the improved process, the results are presented for Amberlite-LA2 in various organic solvents including sunflower oil phase. With the addition of a small amount (5%v/v) of the carrier in sunflower oil, the separation of penicillin G from the fermentation can be performed at the natural pH of fermentation (that is without adding any chemicals for pH adjustment). The percentage extraction of approx. 40-45% was achieved at a circulating flow rate of 13-16 L/h in a hollow-fibre membrane contactor. This result is similar to those reported by many investigators using toxic solvents (such as kerosene). The performance of the carrier-solvent system can be improved if pH and temperature are adjusted to lower values. This would require the media solution to be adjusted again for the fermentation of penicillin G as it requires a pH of 6.5. For recovery from the organic phase, aqueous solutions of sodium carbonate and sodium chloride have shown good results. An aqueous solution of sodium carbonate at pH 11 is able to recover significantly than sodium chloride solution and in a shorter process time of about 1.5 hours. From these studies it can be concluded that sunflower-based system is the preferred organic solvent for extraction because other solvents are very expensive (much more than that of sunflower oil) and do not have renewable sources. This new system offers many process advantages being less toxic, less corrosive, equally effective, environmentally-safe and operator-friendly.