TiO2 Nanowires Based System for Urea Photodecomposition and Dialysate Regeneration

To enable portable kidney dialysis for end-stage renal disease, the regeneration of the dialysate in a closed loop system is a critical technical barrier. Currently dialysis treatment uses ∼120 L of dialysate per 4 h session, to remove urea as well as other toxins from the blood, far exceeding usable weights for a portable system. We have developed an efficient photooxidation system based on hydrothermally grown TiO2 nanowires, UV LEDs, and catalytic gas diffusion barriers to decompose urea from the dialysate at rates sufficient to remove daily production of urea at 15 g/day. With 365 nm LED irradiation of 4 mW/cm2, dialysate simulant solutions of 10 mM urea/0.15 M NaCl photocurrent density of ∼1 mA/cm2 was achieved, corresponding to 40% quantum efficiency in urea decomposition per incident photon. From performance parameters, a feasible portable device with 0.23 m2 active area and a current draw of 11 A is able to decompose a daily 15 g urea production sufficient to regenerate dialysate.