Synthesis of two pH-responsive copolymers in pilot scale and its application in aqueous two-phase system

Recycling pH-responsive aqueous two-phase system (pH-ATPS) has the advantages of low interfacial tension, high recovery, mild condition and low cost. In this paper, two pH-responsive copolymers 4% (w/v) P-ADB4.05 and 3% (w/v) P-MDB3.36 were used to construct a recycling pH-ATPS (the recoveries of two copolymers were both higher than 97%) for partition of demeclocycline and Lincomycin. They were successfully synthesized in pilot scale (500 L) through optimizing the monomer molar ratio and synthesis conditions and the yield of P-ADB4.05 and P-MDB3.36 were 97% and 96% respectively. The characteristics of two scaled-up copolymers were consistent with those synthesized in laboratory scale. The optimal partition coefficient (K) of demeclocycline were 4.223 with 20 mM LiCl at room temperature, respectively. For lincomycin, the K reached 2.629 in the presence of 4 mM MnCl2 at 45 degrees C. Partition of antibiotics in this pH-ATPS can be improved by varying pH, type and concentration of salts and temperature, which means it is available to antibiotics extraction and the further industrial separation.