Extraction and recovery of penicillin G in a hollow-fiber membrane contactor

The effect of feed pH and temperature were examined for the extraction of penicillin G from aqueous solutions. Equilibrium experiments were first carried out to establish the carrier and the solvent for better extraction in the organic phase. The feed pH was varied in the range 4.5-7 to determine the extractability of the carrier-solvent system. Organic phases consisting of the carriers Aliquat 336 and Amberlite LA-2 in the solvents Shellsol TK and oleyl alcohol gave good values of the distribution coefficient at room temperature. The distribution coefficients were greater at temperatures higher than the room temperature. Re-extraction (recovery) experiments were carried out by using an aqueous solution of salts; sodium carbonate performed better than sodium chloride. These processes were scaled up using a pilot-scale hollow-fiber membrane module (HFMM). The module (6 cm × 20 cm) had a total of 10000 microporous polypropylene hollow fibers with an effective mass transfer area of 1.4 m². The extraction was performed by contacting a 'feed' solution containing penicillin G (flowing in the fiber side) with an 'organic phase' of Aliquat 336 in Shellsol TK or oleyl alcohol (flowing on the shell side) of the membrane contactor. An organic phase of 5% Aliquat 336 in both the solvents Shellsol TK and oleyl alcohol achieved extraction at pH 7 in the range 40-45% within 1 h at a recirculating feed flow rate of 14.4 1/h. The operating temperature affected the percentage extraction slightly and it increased with temperature before reaching a plateau at 25-30°C. For recovery of penicillin G from the organic phase, experiments were carried out using aqueous solutions of sodium carbonate and sodium chloride. Sodium carbonate at pH 11.2 gave significantly better recovery (approx. 98%) compared to sodium chloride at pH 6.7 (approx. 38%) within 1.5 h.