Fine-tuning of carbon nanostructures/alginate nanofiltration performance: Towards electrically-conductive and self-cleaning properties

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 trans-port. 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 re-sistivity, 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 fabri-cation parameters. 90% Na2SO4 rejection (7 LMH) is achieved for silane-CaAlg200-10% CNS membranes. Membranes exhibit outstanding electrical conductivity (similar to 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.

Automated summary

Electrically-conductive membranes with enhanced ion selectivity and self-cleaning properties have attracted attention. Carbon nanostructures (CNS) with high electrical conductivity and fast water transport are embedded into Alginate network to fabricate self-cleaning nanofiltration membranes. The membranes exhibit outstanding electrical conductivity and improved swelling/shrinkage resistivity. The rejection profiles of Na2SO4 are optimized and 90% rejection is achieved for silane-CaAlg200-10% CNS membranes. Successful dye/salt separation is achieved with a rejection of 100% for dye and only 3.1% for Na2SO4, and 54% Na2SO4 rejection in the second stage.