Calcium ion crosslinked sodium alginate coated PVDF membrane for improved smart pH-responsive properties

Smart membrane with pH-responsive properties was fabricated by applying calcium ions crosslinked sodium alginate onto the PVDF membrane via a dip-coating approach. Different characterizations were carried out to verify the successful fabrication of the smart membrane. The prepared membrane has excellent pH-responsive property, and its flux can be adjusted by changing the feed solution pH. The smart membrane also possessed excellent smart self-cleaning performance and the milk contaminants were easily removed in low pH solution. Its flux recovery rate can reach 96.3% when washed with water at pH 2.0. In addition, the smart membrane can be effectively used for separating oil from water. Its flux changed with the pH while its separation efficiency is unaffected, and the rejection rate kept above 97.5% in all cases. This research provides a potential strategy to prepare pH-responsive smart membrane using calcium ions crosslinked sodium alginate that can be used in many fields. • Smart membrane with pH-responsive properties was prepared. • The calcium ions crosslinked sodium alginate was applied onto the membrane surface. • The modified membrane exhibits excellent pH-responsive performance. • The modified membrane can also present excellent smart self-cleaning performance. • The modified membranes can also be used for smart separation of acidic oil wastewater.