Preparation of Polyoxometalate-Based Composite by Solidification of Highly Active Cobalt-Containing Polytungstate on Polymeric Ionic Liquid for the Efficient Isolation of Proteinase K

A novel porous polyoxometalate (POM)-based composite (Co(4)PW–PDDVAC) was prepared via the solidification of water-soluble polytungstate (Co(4)PW) on the polymeric ionic liquid dimethyldodecyl-4-polyethylene benzyl ammonium chloride (PDDVAC) via a cation-exchange reaction. The solidification was confirmed by EDS, SEM, FT-IR, TGA, and so on. The strong covalent coordination and hydrogen-bonding interaction between the highly active Co(2+) of the Co(4)PW and the aspartic acid residues of proteinase K endowed the obtained Co(4)PW–PDDVAC composite with excellent proteinase K adsorption properties. Thermodynamic investigations indicate that the adsorption behavior of proteinase K was consistent with the linear Langmuir isothermal model, giving an adsorption capacity as high as 1428 mg g(−1). The Co(4)PW–PDDVAC composite was applied in the selective isolation of highly active proteinase K from Tritirachium album Limber crude enzyme fluid.