Covalent laccase immobilization on the surface of poly(vinylidene fluoride) polymer membrane for enhanced biocatalytic removal of dyes pollutants from aqueous environment

Abstract

Biocatalytic removal with laccase immobilized on diverse membranes offers an attractive option to search alternative to traditional wastewater treatment processes for the removal of high toxic azo dye. In this work, the modified poly(vinylidene fluoride) membrane (PVDF) with chemical stability and high mechanical strength was developed for laccase immobilization via covalent bonding. The key design for the synthesis of biocatalytic membrane is the construction of hybrid bio-inorganic structure on the surface of polydopamine (PDA)-coated PVDF (PDA@PVDF). In this respect, the PDA layer was used as a secondary platform for the grafting of 3-triethoxysilylpropylamine (APTES) modified Fe2O3@SiO2 cubes (FS@cubes) via a solvothermal process, resulting in the formation of FS@cubes-PDA@PVDF membrane. Subsequently, laccase was immobilized on the surface of FS@ cubes-PDA@PVDF via gluteraldehyde (GA) crosslinking (Lac-FS@ cubes-PDA@PVDF). The removal efficiency of congo red by Lac-FS@cubes-PDA @PVDF reached 97.1 % under optimal reaction conditions (pH 7.0 and temperature 35 ℃), which was more efficient than free laccase. Moreover, the as-prepared Lac-FS@cubes-PDA@PVDF not only exhibited an excellent stability after low temperature storage, but also showed an outstanding reusability. Therefore, we believe that this work opens up a potential strategy for removal of other water pollutants, and provide a simple and convenient way for large-scale applications of enzyme-catalysis.