Superhydrophilic membranes produced by biomimetic mineralization for water treatment

Poly(vinylidene fluoride) (PVDF) membrane has been applied in the diverse water treatments, but its inherent hydrophobicity must be adjusted to reduce energy consumption. Herein, high hydrophobicity of PVDF membrane surface was transformed to superhydrophilicity by the combination of mussel-inspired chemistry and biomimetic mineralization. The deposited tannic acid (TA) and polyethylenimine (PEI) induced in situ biomimetic mineralization to form nanosphere and nanowire microstructures on the membrane surface. The highly efficient separation and outstanding antifouling properties were achieved for oil-in-water emulsion and dyeing wastewater treatment. The rejections of nano-ZrO2/PEI-TA/PVDF membranes to BSA, oil, Congo red and methyl blue reached as high as 99.3%, 98.8%, 96.8% and 93.5% (15-fold increment compared to that of pristine membrane), respectively. With rejections to BSA (95.0%), oil (93.9%), Congo red (86.6%) and methyl blue (83.2%), the permeate flux of nano-TiO2/PEI-TA/PVDF membranes reached as high as 1312.6 L/m2 h, showing nearly 7.6-fold increment compared with other reported values. This work developed a novel strategy to fabricate multifunctional separation membranes for environmental remediation. A superhydrophilic membrane with multiple hierarchical structures was fabricated through the combination of mussel-inspired chemistry and biomimetic mineralization to treat dyeing wastewater and oil emulsions highly efficiently.