Fine-tuning of carbon nanostructures/alginate nanofiltration performance: Towards electrically-conductive and...

Electrically-conductive membranes became the center of attention owing to their enhanced ion selectivity and self-cleaning properties. Carbon nanostructures (CNS) attain high electrical conductivity, and fast water transport. Herein, we adopt a water-based, simple method to entrap CNS within Alginate network to fabricate self-cleaning nanofiltration membranes. CNS are embedded into membranes to improve the swelling/shrinkage resistivity, and to achieve electrical-conductivity. The CaAlg PEG-formed pores are tuned by organic-inorganic network via silane crosslinking. Flux/rejection profiles of Na₂SO₄ are studied/optimized in reference to fabrication parameters. 90% Na₂SO₄ rejection (7 LMH) is achieved for silane-CaAlg₂₀₀-10% CNS membranes. Membranes exhibit outstanding electrical conductivity (∼2858 S m^-1), which is attractive for fouling control. CaAlg/CNS membranes are tested to treat dye/saline water via two-stage filtration, namely, dye/salt separation and desalination. A successful dye/salt separation is achieved at the first stage with a rejection of 100%-RB and only 3.1% Na₂SO₄, and 54% Na₂SO₄ rejection in the second stage.