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

[Display omitted] •Two pH-responsive terpolymers were successfully synthesized in pilot scale.•The characteristics of terpolymers synthesized in different scales were similar.•The rescoveries of two terpolymers were both higher than 97%.•A recyclable aqueous two-phase system was constructed for extraction of antibiotics.•The partition coefficient of demeclocycline reached 4.223 with 20 mM LiCl. 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) PADB4.05 and 3% (w/v) PMDB3.36 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 PADB4.05 and PMDB3.36 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 °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.