Hemodialysis generates a substantial volume of spent dialysate containing various uremic toxins, particularly water-soluble compounds such as creatinine. Regeneration and reuse of dialysate require efficient and selective adsorbents capable of removing these toxins. ZSM-5 zeolite is a promising material due to its porous structure, tunable physicochemical properties, and potential to be developed as a molecular recognition material. However, enhancing the selectivity of ZSM-5 toward creatinine remains a challenge. Therefore, this study aimed to develop creatinine-imprinted ZSM-5 (IZ) to enhance the selective removal of creatinine from dialysate and to evaluate its application in a cellulose acetate-based mixed-matrix membrane.

METHODS

ZSM-5 zeolite was synthesized using a hydrothermal method and subsequently modified through a molecular imprinting approach using creatinine as the template molecule. The synthesized ZSM-5, non-imprinted zeolite (NIZ), and imprinted zeolite (IZ) were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) surface area analysis, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Adsorption performance was evaluated by optimizing the contact time, adsorbent dosage, and initial creatinine concentration. Adsorption isotherm, kinetic, and selectivity analyses were also performed. Subsequently, IZ was incorporated into a cellulose acetate-based mixed-matrix membrane and evaluated for creatinine removal under flow conditions.

RESULTS

The results confirmed the successful synthesis of ZSM-5 and the creatinine-specific imprinting process. IZ exhibited a crystallinity of 79%, compared with 57% for the synthesized ZSM-5. The pore diameter increased from 3.22 nm for ZSM-5 to 5.42 nm for IZ, indicating the formation of specific recognition sites for creatinine. IZ demonstrated superior adsorption performance, with an optimum adsorption capacity of 55 mg g⁻¹ within 15 minutes, compared with 36 mg g⁻¹ for ZSM-5 at a contact time of 30 minutes. The creatinine removal efficiency of IZ reached 84%, whereas ZSM-5 achieved 42%. Selectivity analysis demonstrated enhanced creatinine recognition, with a selectivity coefficient 4.074 times higher than that of ZSM-5. The MMM/IZ membrane exhibited an adsorption capacity of 18.7 mg g⁻¹ and a removal efficiency of 28.8%. Overall, molecular imprinting successfully enhanced the selectivity, adsorption capacity, and adsorption rate of ZSM-5, demonstrating its potential as a selective adsorbent for dialysate regeneration and uremic toxin removal.

Author: Yanuardi Raharjo, Ph.D.

Further information about this research can be found in our article:

Yanuardi Raharjo, Maipha Deapati Arief, Novia Amalia Sholeha, Triyanda Gunawan, Dayang Norfizan Awang Chee, Aemi Syazwani Abdul Keyon, Hartati, Aida Rifdatul Aisy, Muhammad Nidzhom Zainol Abidin, and Nur Fariha Mahmuda

ZSM-5 Zeolite with Molecular Imprinting for the Selective Removal of Creatinine from Dialysate: Toward Enhanced Uremic Toxin Clearance, RSC Advances, 2026, 16, 42241.

https:// DOI: 10.1039/d6ra05654g