Kidney disease poses a significant challenge to global health, accompanied by substantial medical expenses. The escalating prevalence of chronic kidney disease on a global scale underscores the urgency of addressing this health crisis. Notably, data from the 2018 Indonesian Basic Health Research reveals a worrisome trend, indicating a rise in chronic kidney disease cases among individuals aged equal or more than 15 years.
In 2013, the prevalence stood at 0.2 %, witnessing a notable surge to 0.38 % in 2018. Moreover, the 2018 Indonesian Renal Registry reports a substantial increase in the number of patients actively undergoing hemodialysis therapy, jumping from 77,892 in 2017 to 132,142 in 2018. This surge necessitates dedicated attention to effective management, emphasizing the imperative role of advancing hemodialysis membrane technology in aiding individuals grappling with kidney failure.
The demand for hemodialysis membranes sees a steep annual rise, both on a national and global scale. To meet this escalating need, continuous development and innovation in hemodialysis therapy are imperative, ensuring attributes such as safety, comfort, reliability, and efficiency. However, the high cost of hemodialysis membrane therapy stems from its dependence on high-quality water and substantial amounts of dialysate.
Water plays a pivotal role in various facets of hemodialysis, from crafting dialysate solutions to the rinsing and reprocessing of dialysis machines and membranes. Astonishingly, a patient undergoing thrice-weekly treatment consumes approximately 80,000 L of pure water annually, a staggering amount surpassing the average per capita household water consumption in various countries, including Brazil (42,500 L), Australia (54,500 L), France (55,000 L), and Indonesia (52,560 L).
Considering the current estimate of 2.5 to 3.0 million patients on hemodialysis globally, the total water consumption exceeds 200 billion liters. Looking ahead to 2025, with an anticipated 4 million hemodialysis patients worldwide, the challenges extend beyond healthcare budgets to encompass ecological impacts. The colossal demand for water and electricity, coupled with waste production, poses a substantial threat to the planet. Moreover, the hemodialysis process generates a significant volume of used dialysate solution, necessitating further processing due to its unavoidable nature.
Addressing the critical challenges of water quality and scarcity in today’s environment is paramount, given the substantial rise in water demand driven by the increasing global population. A pivotal solution lies in the processing and reuse of used dialysate solutions for hemodialysis, presenting a crucial avenue for cost reduction and fostering environmentally friendly practices within the realm of hemodialysis.
This approach not only holds the potential to significantly decrease hemodialysis costs but also promotes a more efficient utilization of water resources. To advance towards the aspirational objective of “green dialysis”, it becomes imperative to integrate environmental sustainability as a fundamental component within the overarching design and development of hemodialysis systems. This holistic approach, particularly in terms of optimizing water consumption for dialysate, is essential for achieving more ecologically responsible and resource-efficient hemodialysis practices.
This study investigates the potential of mixed matrix membrane adsorbers (MMMAs) to recycle dialysate wastewater by combining adsorbents and filtration membranes as filters and scavengers to eliminate impurities from used dialysate water. Previous research by Pascale et.al. demonstrated the efficacy of MMMAs, composed of cellulose acetate and sorbent fillers such as activated carbon, ZSM-5, and clinoptilolite, in removing urea, creatinine, and uric acid from aqueous solutions. Saiful et.al. advanced the field by developing MMMAs capable of simultaneous filtration and adsorption in a single stage, specifically applicable to hemodialysis.
Despite their reusability and high performance, MMMAs face challenges in sourcing abundant, inexpensive, and environmentally friendly raw materials for membrane polymers and adsorbents. Additionally, there is a focus on enhancing the configuration of mixed matrix materials, exploring options like mixed matrix nanofibers, and augmenting the efficacy of adsorbents through modification and synthesis of new types. This integration overcomes material limitations, resulting in increased porosity and surface area. This research provides a novel approach to integrating advanced carbon-modified zeolite derivatives into MMMAs, aiming to enhance membrane efficiency and open pathways for further innovations in water reclamation technology.
Methods
Initially, the synthesis of ZCC and ZTC was conducted referred to Gunawan et al. ZCC and ZTC were employed as an adsorbent filler, integrated into the membrane matrix during the fabrication process of membrane. Prior to use, polymers (PES and PVP) were subjected to a one-day drying period at 50 ◦C in an oven. Subsequently, ZTC was dispersed in NMP solvent, and a stepwise dissolution of PES and PVP was carried out to achieve the dope solution, with specific compound proportions.
The dope solution was stirred for 2 days at 60 ◦C to ensure optimal dispersion in dope solution. Following this, the solution underwent 24 h of degassing in a sonicator to eliminate bubbles. The degassed solution was then cast onto a clean glass plate using a casting knife with a controlled gap thickness (300 μm). Immediately after casting, the plate was immersed in a coagulation bath filled with deionized (DI) water at room temperature for 2 min. This immersioninitiated phase separation via solvent and non-solvent exchange, resulting in the formation of a porous membrane. The resulting flatsheet membrane was carefully transferred to a second DI water bath, where it was soaked for 24 h to remove residual solvent and stabilize its structure.
These steps, particularly the specific coagulation time and filler dispersion process, were designed to optimize membrane porosity and ensure the uniform integration of the adsorbent fillers. Thus the materials and the MMM developed characterized by XRD to assess the lattice structures and determine the crystallite size, FE-SEM to examined the morphology, SEM-EDX was used to study morphological aspects as well as elemental analysis on membrane, FTIR to studied the chemical bonds and functional groups of the membrane, and AFM to assessed the surface roughness of MMM. Moreeover, the prosity, water flux, and removal of uremic toxins were evaluated for the MMM performance.
Results
The MMMAs were successfully fabricated via NIPS method with the incorporation of ZCC and ZTC fillers. SEM and XRD analyses verified the successful synthesis of ZCC and ZTC, demonstrating the retention of the zeolite-Y structure and amorphous nature, along with notable differences in their particle sizes (680 and 379 nm) and crystallite sizes (0.45 and 0.02 nm). FTIR analysis indicated potential hydrogen bonding interactions between ZCC and PVP, but no such interactions were observed between ZTC and the membrane matrix. SEM and AFM characterization revealed morphological differences and variations in surface roughness, with ZCC enhancing hydrophilicity and porosity, while ZTC, being more hydrophobic, reduced surface roughness.
Performance testing showed that the PPK-0.2 membrane achieved superior urea and creatinine rejection rates of 93.05 % and 98.95 %, respectively, due to the combined effect of molecule trapping in ZTC micropores and physical adsorption from the polymer matrix. In contrast, the enhanced performance of the PPZ-0.2 membrane was primarily driven by physical adsorption through hydrogen bonding. This study, the first to comprehensively compare ZCC and ZTC fillers in this context, demonstrates the high potential of ZCC and ZTC as fillers for mixed matrix membranes in dialysate purification, offering promising advancements in water and wastewater treatment applications.
Author: Yanuardi Raharjo, Ph.D.
Detailed information from this research can be seen in our article at:
https://www.sciencedirect.com/science/article/abs/pii/S1226086X2400875X
