A porous mixed matrix membrane adsorber for toxin removal from water

Renal failure is a debilitating and chronical condition in which kidneys are no longer able to remove toxins and excess fluid from the body. For patients with terminal kidney disease, that were approximately 3.2 million at the end of 2017, haemodialysis is the primary support treatment. Two of the main drawbacks of the therapy are the massive use of water, about 120 l per patient per treatment, and the uncomplete removal of uremic toxins from blood. Our work is focused on the preparation and characterization of novel porous Mixed Matrix Membranes Adsorbers (MMMAs) to remove the toxic compounds present in the spent dialysate side f the process. The purified water might be reused, to produce new dialysis fluid for the same patient, in order to reduce substantially the amount of pure water required for a single dialysis treatment. Porous Mixed Matrix Membrane Adsorbers based on cellulose acetate were fabricated and modified with the addition of a natural zeolite, ZUF, to enhance the affinity towards urea, creatinine and uric acid. Water permeability tests and batch adsorption tests were performed on the prepared adsorbers and encouraging results have been obtained. According to the different amount of ZUF added, which ranges from 5 to 30 wt% of ZUF, it is possible to notice an increase in water permeability from 728 to 1379 l/(hm2bar). Moreover, the presence of ZUF increases the removal capacity of the pure cellulose acetate membrane up to 83% for urea and up to 28% for creatinine, while for uric acid it remains approximately the same. In parallel to this work, other adsorbent materials, like ZSM-5 zeolite and activated carbon, have been tested in batch adsorption experiments with the different toxins, to investigate their potential use as fillers for the MMMAs, To simulate real process conditions, experiments with mixtures of toxins are ongoing, while tests in a real dialysis set-up will be performed with the most promising MMMA.

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