Quaternary Ammonium Modified Mg–Al Layered Double Hydroxide Based Composite Aerogel Adsorbents for Removal of Hippuric Acid During Hemodialysis

As the global population of chronic kidney disease (CKD) patients continues to expand, high-performance adsorbents for uremic toxins have emerged as a critical solution to alleviate dialysis treatment challenges. In this work, a layered double hydroxide (Mg–Al LDH) was prepared via a facile hydrothermal approach and subsequently functionalized for adsorption of protein-bound toxins by organosilicon quaternary ammonium salt (Q-Mg–Al LDH). The synthesized Q-Mg–Al LDH was then incorporated into sodium alginate (SA) solution to achieve a three-dimensional Q-Mg–Al LDH/SA composite aerogel (SA-Q) by freeze-drying for easy maneuverability as adsorbents. Specifically, the organosilicon quaternary ammonium-grafted LDH (Q-Mg–Al LDH) offered both long alkyl chain and positively charged quaternary ammonium moieties, enabling synergistic adsorption through electrostatic and hydrophobic interactions, thereby exhibiting superior adsorption capacity (222.7 mg/g) for hippuric acid (HA, one typical protein-bound uremic toxin). The optimized SA-Q possessed outstanding adsorption capabilities (141.8 mg/g); more importantly, it could maintain a 95% removal rate even after 8 cycles, and also could selectively remove the diffused HA in the dialysate during hemodialysis, indicating its excellent operability and recyclability. This work demonstrated a promising strategy for constructing advanced adsorbents to eliminate uremic toxins from dialysate to facilitate the development and popularization of miniaturized hemodialysis equipment.