Collagen fibers with tuned wetting properties for dual separation of oil-in-water and water-in-oil emulsion†
Tuning the wettability of materials is of significance in developing efficient separation materials. Herein, we tuned the wetting properties of collagen fibers (CFs) by surface decoration with Zr4+, and the resultant composite fibers were effective for dual separation of oil-in-water (O/W) and water-in-oil (W/O) emulsions. The as-prepared composite fibers were underwater superoleophobic, with an underwater oil contact angle of 158.4°, which enabled the successful separation of a variety of O/W emulsions by rejecting oil selectively while permitting water permeation. Furthermore, the composite fibers featured underoil hydrophilicity as well as large water-absorbing capacity (4.17 g g−1), which allowed for separating diverse W/O emulsions by capturing water from the W/O emulsions. For the dual separation, the separation efficiency was high up to 99.9995%, and the flux reached 3031 L m−2 h−1. The composite fibers also showed long-term separation stability and good recycling capability. Our strategy might be applied for developing other separation materials that could be applicable for achieving dual separation of O/W and W/O emulsions.