Abstract: In an embodiment, a process of purifying a polycarbonate from an interfacial polymerization product mixture comprising an aqueous phase and an organic phase comprising a first organic solvent, the polycarbonate, a catalyst, and ions, the process comprises: separating the aqueous phase and the organic phase to form a separated aqueous feed stream and a separated organic stream; extracting the catalyst and the ions from the separated organic stream to form a purified polycarbonate stream and an extracted aqueous feed stream, wherein at least one of the separated aqueous feed stream and the extracted aqueous feed stream comprise an organic portion and an aqueous portion; purifying an aqueous stream comprising one or both of the separated aqueous feed stream and the extracted aqueous feed stream by adjusting a viscosity of the organic portion to be less than or equal to 40 centipoise by adding a second organic solvent to the aqueous stream to form a combined stream; optionally, adjusting a ratio of the aqueous po