Background
The standard weekly treatment for end‐stage renal disease patients is three 4‐h‐long hemodialysis sessions with each session c'onsuming over 120 L of clean dialysate, which prevents the development of portable or continuous ambulatory dialysis treatments. The regeneration of a small (~1 L) amount of dialysate would enable treatments that give conditions close to continuous hemostasis and improve patient quality of life through mobility.
Methods
Small‐scale studies have shown that nanowires of TiO2 are highly efficient at photodecomposing urea into CO2 and N2 when using an applied bias and an air permeable cathode. To enable the demonstration of a dialysate regeneration system at therapeutically useful rates, a scalable microwave hydrothermal synthesis of single crystal TiO2 nanowires grown directly from conductive substrates was developed. These were incorporated into 1810 cm2 flow channel arrays. The regenerated dialysate samples were treated with activated carbon (2 min at 0.2 g/mL).
Results
The photodecomposition system achieved the therapeutic target of 14.2 g urea removal in 24 h. TiO2 electrode had a high urea removal photocurrent efficiency of 91%, with less than 1% of the decomposed urea generating NH4+ (1.04 μg/h/cm2), 3% generating NO3− and 0.5% generating chlorine species. Activated carbon treatment could reduce total chlorine concentration from 0.15 to <0.02 mg/L. The regenerated dialysate showed significant cytotoxicity which could be removed by treatment with activated carbon. Additionally, a forward osmosis membrane with sufficient urea flux can cut off the mass transfer of the by‐products back into the dialysate.
Conclusion
Urea could be removed from spent dialysate at a therapeutic rate using a TiO2 based photooxidation unit, which can enable portable dialysis systems.
Biofidelic numerical models have been developed such as the coil-resolved model to study hemodynamics in the treated aneurysm. In this model, the geometry of the coils is recreated from high-resolution tomography scans of a phantom aneurysm treated with coils. However, this model hasn’t been validated. The purpose of this work is to validate the coil-resolved model. To achieve this, we used the planar-laser induced fluorescence technique on phantom aneurysm treated with coils and measured the residence time and the evolution of rhodamine concentration during the washout. We run passive scalar simulations with the coil-resolved model and measured the evolution of concentration over time. The comparison of the numerical and the experimental results shows that the coil-resolved model reproduces the hemodynamics of the experimental setup. Therefore it can be used as a reference to study hemodynamics in the treated aneurysm or to validate porous media models developed for treatment outcomes prediction.
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