Regeneration of dialysis solution by dual-layer hollow fiber mixed matrix membrane (DLHF-MMM) incorporated with amine-functionalized mesoporous silica nanoparticles

A large amount of purified water is used in conventional hemodialysis (HD) for treating end-stage kidney disease (ESKD). To minimize the water demand and waste generation, the regeneration of dialysis solution is considered the most efficient control strategy. In this study, an innovative dual-layer hollow fiber (DLHF) mixed matrix membrane (MMM) incorporated with amine-functionalized mesoporous silica nanoparticles (MPS-NPs) was developed to regenerate spent dialysis solution. The fabricated DLHF-MMM configuration enabled the continuous removal of small, medium, and large weight uremic toxins (UTs) through dual mechanisms. The inner layer composed of polyethersulfone (PES) and polyethylene glycol (PEG) rejected medium-large weight UTs (i.e., MW > 500 Da) via the molecular sieving. Meanwhile, the outer layer containing amine-functionalized MPS-NPs effectively removed small weight UTs, such as urea and creatinine. The DLHF-MMM with 6 wt% of amine-functionalized MPS-NPs demonstrated the most favorable characteristics, i.e., high water permeability (298.6 +/- 3.2 mL/m(2).h.mmHg) and adsorption capacity of urea (523.5 mg/g) and creatinine (28.1 mg/g). Notably, the optimal membrane (DLHF-4) also achieved favorable removal rates from the spent dialysis solution of actual patient, i.e., urea (74.4 %), creatinine (56 %), hippuric acid (16.1 %), and lysozyme (58.7 %, additionally spiked as a mimicking for beta-2 microglobulin). These results indicate that the fabricated DLHF-MMM in this study can effectively overcome the challenges posed by the complex matrix components. Overall, the results of this study demonstrate that the DLHF-MMM incorporated with amine-functionalized MPS-NPs is a promising and potential tool for the regeneration of dialysis solution. Furthermore, this approach can contribute to water conservation and reduce the burden on wastewater treatment processes associated with wastewater generated from conventional HD.