Simultaneous adsorption and two-dimensional confined mass transfer separation of iodide ions by a novel interlayer-based thin-film nanocomposite membrane

Escalating threats by radioactively contaminated water highlights the urgency for effective cleanup strategies nowadays. In this article, a novel interlayer-based thin-film nanocomposite (iTFN) membrane was designed and applied to treat simulated radioactive wastewater contaminated by iodide ions for the first time. An ultrathin polyamide separation layer was constructed via interfacial polymerization on a confined interlayer with silver nanoparticles intercalated graphene oxide nanosheets (Ag-GO). Both adsorption affinity and two-dimensional confined mass transfer separation mechanism by the stacked Ag-GO interlayer played important roles in water permeance and rejection ratio, together with the size-sieving effect by the polyamide layer. SEM and AFM results proved the typical ridge-and-valley structures of polyamide layers, and the stacked Ag-GO interlayers helped to generate finer polyamide nodule structures with smoother surface morphology. In addition, interpenetrating the polyamide layer into the stacked Ag-GO interlayers may enhance the compatibility between the two layers and improve the overall stability. The optimized iTFN membrane exhibited a 93.81 % iodide ion rejection ratio and 35.0 L m -2 h −1  bar −1 permeability flux. In addition, the iTFN membrane could handle solutions with a wider pH range and higher ion concentrations. All these could provide new application horizons for treating radioactive wastewater with polyamide nanofiltration membranes.