TiO₂ nanoparticles were synthesized via the sol-gel method, which is widely recognized for producing high-purity nanoparticles with tailored properties [11] . A solution containing 100 mL of TTIP and 500 mL of ethanol was prepared and stirred continuously for 30 minutes at room temperature. Subsequently, deionized water and hydrochloric acid were added dropwise in a 1.2:1 molar ratio under constant stirring at 200 rpm. This process was maintained for 2 hours at 21˚C, ensuring the solution’s pH was adjusted to 3 [9] . To facilitate hydrolysis and condensation reactions, the solution was continuously stirred under controlled temperature conditions, allowing for the gradual formation of TiO₂ nanoparticles. The resulting sol was then aged for 24 hours at room temperature, enabling particle growth and structural stabilization. The formed gel was dried at 120˚C for 2 hours to remove residual solvents and promote crystallization. Finally, the dried gel was calcined at 450˚C for 4 hours to enhance its crystallinity and optimize its surface area for effective water purification applications.

The synthesized nanoparticles were characterized using advanced analytical techniques to confirm their structural, morphological, and chemical properties. Fourier-transform infrared (FTIR) spectroscopy was employed to identify functional groups in the range of 4000 - 400 cm⁻¹, a method previously validated in similar studies [13] . Scanning electron microscopy (SEM) (Hitachi SU 3500) was used to examine the surface morphology and particle size distribution, while X-ray diffraction (XRD) analysis (X’Pert PRO, PANalytical) provided insights into the crystalline structure and phase composition [14] . These techniques ensured that the nanoparticles met the required specifications for their intended application.

The TiO₂-based filter was fabricated by combining synthesized TiO₂ nanoparticles with polyethylene glycol (PEG) in a 7:3 weight ratio. To improve dispersion, the TiO₂-PEG mixture was ultrasonicated for 1 hour before further processing. To enhance the structural stability, 0.1 g of silica particles was added to the mixture, as reported in prior nanoparticle-based filter designs [15] . The resulting mixture was thoroughly homogenized, compressed into disc form using a hydraulic press, and heated at 100˚C for 2 hours. Following this step, the discs were subjected to gradual heating at 200˚C for 1 hour before reaching the final sintering temperature of 305˚C. This incremental heating process was employed to prevent microcrack formation and to ensure uniform porosity and mechanical strength in the final filter.

The collected water samples were subjected to comprehensive physicochemical and microbiological analyses to evaluate the performance of the TiO₂-based filter. Parameters such as pH, conductivity, and hardness were measured using standard protocols, with a DR5000 spectrophotometer providing accurate quantification of chemical properties [4] . Metal concentrations, including essential and toxic elements, were determined using Flame Atomic Absorption Spectrophotometry (Perkin-Elmer 2380) [6] . The filtration efficiency was compared with conventional reverse osmosis (RO) and activated carbon filtration techniques to assess the superiority of the TiO₂-based filter in removing heavy metals and organic contaminants.

The bacteriological quality of the water samples was assessed using heterotrophic plate counts on R2A agar medium, which is optimal for detecting heterotrophic bacteria in low-nutrient environments [3] . Endotoxin levels, which are critical for evaluating water quality in hemodialysis, were quantified using the Limulus Amebocyte Lysate (LAL) gel-clot method [8] . Additionally, the operational costs, energy requirements, and long-term maintenance needs of the TiO₂-based filter were analyzed and compared with existing advanced purification methods. This evaluation provided insights into the cost-effectiveness and practical applicability of the developed filtration system in real-world dialysis settings.

While the performance of the filtration system based on TiO₂ was quite good in chemical and microbiological contaminant removal, some limitations still occurred. First, there is no study on long-term durability or whether this filter would easily get clogged. Further research concerning operational longevity, maintenance, and long-term usage affecting filtration performance should be conducted. Second, TiO₂ nanoparticles have been widely regarded as antimicrobial agents; however, toxicity has not been deeply assessed in this work. Further studies are needed regarding health risks, nanoparticle leaching, and environmental implications with thorough in vitro and in vivo toxicity testing. Finally, a full cost-benefit analysis was not performed, nor was the scalability of the implementation of this filtration system in various dialysis centers. Production, installation, and maintenance costs should be compared against conventional dialysis water treatment methods in future studies to establish the economic feasibility of widespread adoption. The effort put into addressing these gaps will enhance the understanding of how to practically apply TiO₂-based filtration systems in hemodialysis water purification.

Table 1 and Figure 1 assessed the microbial, endotoxin, and chemical quality of water samples from reverse osmosis (RO) systems used in dialysis across three tertiary healthcare institutions (RC1, RC2, RC3) and tap water (TP). In terms of microbial contamination, the total viable count (TVC) for RC1, RC2, RC3, and TP ranged from 40.18 CFU/ml to 60.20 CFU/ml, meeting the dialysis water limit (<100 CFU/ml) but exceeding the action limit (AL) of 50 CFU/ml in RC2 and TP. Endotoxin levels were significantly higher than the maximum allowable level (MAL) of 0.25 EU/ml for dialysis water and 0.5 EU/ml for dialysis fluid, with RC1, RC2, RC3, and TP reporting values of 1.07, 1.97, 2.5, and 3.95 EU/ml, respectively. pH values ranged from 7.0 to 8.2, staying within the acceptable range for dialysis processes. While, Table 1 and Figure 1 reveal critical insights into water quality challenges. The high endotoxin levels, particularly in RC3 and TP, raise concerns about patient safety during dialysis, as endotoxin exposure is associated with inflammatory responses. These findings align with those of Pathak, Elan, and Devi [38] , who identified endotoxin contamination as a recurrent issue in dialysis water systems. Additionally, the microbial counts exceeding AL in some samples underscore the need for stringent monitoring, consistent with the recommendations of the CDC [39] . The higher microbial and endotoxin levels in TP compared to RO-treated samples highlight the importance of reverse osmosis in achieving improved water quality, as supported by the Renal Fellow Network [40] . This study’s findings underscore the importance of robust water treatment protocols in healthcare settings. Elevated endotoxin levels are consistent with the findings of Zhuang and Chen [41] , who highlighted the limitations of conventional water treatment systems in effectively reducing endotoxin levels. The integration of titanium dioxide (TiO₂) nanoparticles for water purification, as demonstrated in this study, offers a promising solution to these challenges. Wang and Wu [42] emphasize the efficacy of TiO₂ in removing microbial and endotoxin contaminants, supporting its application in dialysis water treatment. Moreover, Tiwari and Sharma [43] documented the photocatalytic properties of TiO₂ nanoparticles, enhancing their suitability for healthcare applications. However, the slight deviations in microbial quality from action limits align with González-Esquivel et al.

MAL = Maximum Allowable Level, AL = Action level (typically 50% of maximum level).

[44] , who noted potential challenges in ensuring complete microbial elimination in dialysis water systems. Similarly, Shirdareh and Nasiri [45] observed variations in microbial contamination control, emphasizing the need for innovative technologies like nanoparticle-enhanced filtration. On the other hand, studies like Amara, Boulahdour, and Benhamouda [46] caution against the potential toxicological effects of TiO₂ nanoparticles, suggesting further evaluations for clinical safety and efficacy. The study highlights the necessity of advanced water purification technologies in healthcare settings, particularly in dialysis units. The findings reinforce the significance of integrating TiO₂ nanoparticle-based filters to enhance microbial and endotoxin removal, contributing to safer dialysis water. As supported by Kaur and Singh [47] , adopting emerging nanomaterials can bridge gaps in current water treatment practices. However, ensuring consistent adherence to international standards, as outlined by ANSI/AAMI/ISO [8] , remains critical for patient safety. Future implementations should consider long-term monitoring and toxicity assessments to optimize the efficacy and safety of nanoparticle-based filtration systems.

Table 2 and Figure 2 present the concentrations (in ppm) of critical electrolytes (calcium, magnesium, aluminum, and lead) in dialysis water across three sample collection points (RC1, RC2, and RC3) and a total pooled sample (TP). Calcium levels ranged from 0.537 ppm in RC3 to 1.479 ppm in TP, while magnesium showed the highest concentration in TP (2.836 ppm) and the lowest in RC1 (1.624 ppm). Aluminum concentrations were fairly consistent, ranging from 0.802 ppm in RC2 to 1.038 ppm in TP. Lead concentrations, a key toxic contaminant, peaked at 0.538 ppm in RC2 and showed the lowest value of 0.120 ppm in RC1. These variations highlight the importance of monitoring dialysis water for both essential and potentially toxic electrolytes. While Table 2 and Figure 2 underscore the variability in water quality across sampling points, revealing that certain contaminants,

particularly lead and aluminum, exceeded acceptable thresholds for dialysis water safety as outlined by the Centers for Disease Control and Prevention [39] . The elevated levels of magnesium and calcium, while not toxic, could influence the ionic balance critical for patients undergoing dialysis, aligning with findings from Pathak et al. [38] . Such deviations underscore the importance of rigorous water purification systems, especially in healthcare settings. The data is significant to the overall study as it emphasizes the need for effective filtration technologies in dialysis water treatment, particularly the role of advanced materials like titanium dioxide nanoparticles [43] . The concentrations of aluminum and lead suggest potential contamination sources that could compromise patient safety, highlighting the critical role of nanomaterials in enhancing filtration efficiency [41] [48] . This aligns with studies advocating for stricter regulations and innovations in dialysis water treatment [40] . Table 2 and Figure 2 bear significant real-world implications. High lead concentrations, as seen in RC2, can exacerbate renal complications in dialysis patients, a concern previously highlighted by Shirdareh and Nasiri [45] . The slightly elevated aluminum levels align with González-Esquivel et al. [44] , who reported similar findings in dialysis water, attributing them to inadequate filtration protocols. Furthermore, the increased magnesium and calcium levels may contribute to mineral imbalance, reinforcing recommendations by Kaur and Singh [47] for incorporating nanotechnology to achieve precise contaminant removal. Advanced purification methods, such as titanium dioxide nanoparticle-based systems, have demonstrated efficacy in reducing aluminum and lead levels in dialysis water, as supported by studies like Wang and Wu [42] . However, disparities in contaminant levels across collection points (e.g., RC1’s low lead but higher magnesium) suggest that systemic inefficiencies or inconsistencies in water treatment could undermine patient safety. This necessitates routine monitoring and potential deployment of hybrid nanomaterial systems, as emphasized by Zhang and Li [49] . Ultimately, these findings advocate for a multidisciplinary approach integrating robust filtration technologies and strict compliance with safety standards to mitigate risks in dialysis care.

The SEM analysis results ( Figure 3 ) reveal critical characteristics of sol-gel-synthesized TiO₂ nanoparticles, including a lump-like crystalline morphology, small particle size (1.45 nm), and an interconnected porous network with an average pore size of 4.11 µm. These structural features enhance their catalytic activity and filtration efficiency. The findings align with the work of Liu & Zhang [48] , who emphasized that the small particle size and anatase phase of TiO₂ nanoparticles improve their photocatalytic properties, essential for water purification applications. Similarly, Kaur & Singh [47] highlighted that advanced nanomaterials, such as TiO₂, exhibit superior performance due to their high surface area and hierarchical pore structures, supporting the observed synthesis outcomes. The bulk

density of 0.58 g/cm³ and uniform morphology distribution were also consistent with Shukla & Kumar [50] , who noted that TiO₂ materials with optimized structural parameters balance effective contaminant removal and fluid throughput, particularly for applications like dialysis water treatment. Moreover, Zhuang & Chen [41] demonstrated that TiO₂ nanoparticles significantly reduce contaminants in hemodialysis water, correlating with the observed potential of the synthesized materials for physical filtration and photocatalytic degradation. Contrary to conventional mesoporous TiO₂ materials (2 - 50 nm), the larger pore size observed in this study may raise concerns about reduced filtration efficiency. However, the work of Wang & Wu [42] and Pathak et al. [38] suggest that larger pores in advanced filtration systems can enhance fluid throughput without compromising the removal of larger contaminants, making the materials suitable for dialysis and other high-throughput water treatment systems. Additionally, the uniform morphology supports findings by González-Esquivel et al. [44] that consistent structural characteristics are vital for reproducibility and efficiency in water purification technologies. The SEM analysis demonstrates that sol-gel-synthesized TiO₂ nanoparticles possess a unique combination of small particle size and hierarchical porous structure, enhancing their catalytic and filtration potential. These features make them particularly suited for water treatment systems, including dialysis, where high throughput and contaminant removal are crucial. The structural and morphological characteristics observed strongly align with recent advancements in nanotechnology and photocatalytic applications as described in previous studies. The study underscores the viability of using sol-gel-synthesized TiO₂ nanoparticles for water treatment applications, bridging material science and healthcare. The anatase phase formation and hierarchical structure offer a foundation for addressing water contamination challenges, particularly in dialysis systems where water purity is critical for patient safety. By optimizing the structural properties of these nanoparticles, the research contributes to the broader goal of improving water purification technologies, a focus highlighted in works like Xu & Zhang [51] and Amara et al. [46] . The findings ( Figure 3 ) have significant real-world implications, especially in healthcare settings requiring stringent water quality standards. The enhanced properties of TiO₂ nanoparticles can improve dialysis water treatment systems, reducing the risk of patient exposure to contaminants and enhancing overall health outcomes. Beyond dialysis, these nanoparticles can be applied in municipal water treatment facilities, industrial wastewater management, and portable filtration systems, addressing global challenges in water scarcity and contamination. Furthermore, the study’s insights into optimizing nanoparticle synthesis can guide future innovations in nanomaterial-based water purification technologies.

The synthesized TiO₂ nanoparticles ( Figure 4 ) exhibited strong photocatalytic properties, as demonstrated by UV-visible spectrum analysis. The absorption spectrum revealed significant activity in the UV range (320 - 340 nm), with peak absorbance values of 0.8701 at 320 nm and 1.0321 at 340 nm. A maximum absorption peak at 330 nm ( Figure 5 ) further supported the synthesis of anatase-phase TiO₂ nanoparticles. These findings are consistent with the optimal analytical range (0.1 - 1.5) for photocatalytic applications [52] [53] . The absorption profile corresponds to the standard characteristics of anatase-phase TiO₂, which typically demonstrates strong UV absorption between 300 and 400 nm. This suggests the successful synthesis of nanoparticles with desirable properties for photocatalytic applications. The confirmation of anatase-phase TiO₂ nanoparticles is significant due to this phase’s superior photocatalytic activity compared to the rutile phase. Anatase TiO₂ demonstrates enhanced electron-hole pair generation, which increases reactivity and reduces recombination under UV irradiation.

These properties are crucial for degrading contaminants in water. The ability of the synthesized nanoparticles to absorb UV light efficiently within the tested spectrum aligns with their potential use in water treatment, specifically in removing pollutants and improving water quality for industrial, domestic, and healthcare applications. This makes anatase-phase TiO₂ particularly advantageous for addressing global water challenges. The results align with existing literature emphasizing the effectiveness of TiO₂-based photocatalysis in water treatment. Araña and Pulgarin [54] reviewed the superior photocatalytic disinfection capacity of TiO₂, while Chong et al. [55] highlighted its efficiency in bacterial inactivation. Similarly, Elshafie and Ghanem [56] noted the practical utility of TiO₂ nanoparticles in hemodialysis water purification systems. Moreover, Makowski and Wardas [57] and Wei and Yang [58] demonstrated the relevance of TiO₂ for purifying drinking water in healthcare contexts. These findings are further supported by Liu et al. [59] and Kaur et al. [47] , who emphasized the innovations in nanotechnology that enhance TiO₂’s photocatalytic efficiency. The consistency of the present study with prior research underscores the potential of anatase-phase TiO₂ nanoparticles in addressing water contamination challenges, particularly in healthcare and industrial applications. The study confirms the successful synthesis of anatase-phase TiO₂ nanoparticles with strong photocatalytic activity in the UV spectrum. These nanoparticles exhibit optimal properties for water purification due to enhanced UV absorption and photocatalytic reactivity, making them suitable for degrading contaminants effectively. This research contributes to the growing body of evidence supporting the application of TiO₂ nanoparticles in water purification technologies. By confirming the synthesis of high-performance anatase-phase TiO₂, the study advances the development of more efficient and reliable water treatment solutions, addressing critical environmental and public health challenges.

Figure 6 illustrates the concentration (in ppm) of calcium (Ca), magnesium (Mg), aluminum (Al), and lead (Pb) before and after treatment across four test points: RC1, RC2, RC3, and TP. The results show a consistent reduction in the concentrations of all four elements after treatment. Magnesium demonstrates the highest initial concentrations, especially at RC2, followed by a significant reduction post-treatment. Calcium also shows notable decreases across all test points, while aluminum and lead exhibit smaller initial concentrations but still show reductions after treatment. The findings of Figure 6 align closely with existing literature on the photocatalytic potential of TiO₂ nanoparticles in water treatment. Araña and Pulgarin [54] and Carey and Oliver [60] highlighted TiO₂’s effectiveness in reducing heavy metals, including lead, during water disinfection and wastewater treatment. Similarly, Chong et al. [55] and Elshafie and Ghanem [56] emphasized TiO₂’s ability to degrade contaminants and improve water quality for hemodialysis systems. Makowski and Wardas [57] confirmed its utility in removing aluminum and lead in drinking water purification, while Liu et al. [59] and Kaur et al. [47] noted advancements in TiO₂-based nanotechnologies for enhanced contaminant removal. Additionally, Shiraishi and Matsumoto [61] supported its application in hemodialysis systems for trace metal elimination. The observed reductions in calcium and magnesium concentrations in Figure 6 are consistent with Tiwari and Sharma’s [43] findings on TiO₂’s role in addressing water hardness, further solidifying its versatility as a photocatalyst in diverse water treatment applications. The key finding from Figure 6 is the effectiveness of the treatment method in reducing the concentrations of these metal ions, with magnesium showing the

most significant reduction. This outcome highlights the efficiency of the photocatalytic process, particularly for water contaminants that pose a risk to both environmental and public health. Figure 6 underscores the effectiveness of the synthesized TiO₂ nanoparticles in removing harmful contaminants from water. The reduction in calcium, magnesium, aluminum, and lead concentrations demonstrates the utility of this treatment in mitigating water pollution and improving water quality. The findings are aligned with the broader aim of utilizing photocatalysis as a sustainable and effective water purification strategy, particularly for environments with complex contamination profiles. These results have substantial implications for environmental management, public health, and industrial applications. For example, the ability to reduce lead, a known toxic heavy metal can address public health challenges, particularly in regions reliant on untreated water. The process’s effectiveness for magnesium and calcium also points to its potential in addressing scaling issues in industrial water systems. Furthermore, this technology could significantly benefit hemodialysis systems, ensuring water safety for patients in healthcare settings.

Table 3 and Figure 7 show the total viable counts (TVC in cfu/ml), endotoxin units (EU in EU/ml), and pH levels of water samples across four categories: RC1, RC2, RC3, and TP. TVC values after treatment ranged from 8.96 to 15.89 cfu/ml, while EU levels ranged between 0.15 and 1.5 EU/ml. The pH values varied between 6.5 and 7.4. The corresponding Figure 8 illustrates a significant reduction in TVC for all water samples post-treatment, with reductions ranging from approximately 78% to 85% relative to pre-treatment values. The highest TVC reduction occurred in RC1, while TP displayed the highest post-treatment TVC concentration. The primary takeaway is the effectiveness of the applied treatment in significantly reducing microbial loads (TVC) across all samples, suggesting a robust disinfection process. The pH values remained within acceptable drinking water standards, further supporting the treatment’s suitability for water purification. The variations in EU levels reflect the residual microbial byproducts, with TP showing the highest endotoxin levels, indicating room for optimization in the treatment process. These findings are pivotal in advancing water treatment methodologies, particularly for settings requiring stringent microbial load control, such as healthcare and hemodialysis. The results align with findings from numerous studies highlighting the efficacy of titanium dioxide (TiO₂) photocatalysis in water disinfection. Araña and Pulgarin [54] emphasized TiO₂’s capacity to reduce microbial loads, corroborating the observed TVC reductions. Carey and Oliver [60] similarly reported significant microbial reductions in wastewater treated with TiO₂. Chong et al. [55] confirmed TiO₂’s potential for deactivating bacteria and degrading microbial byproducts, consistent with reduced EU levels in this study. Elshafie and Ghanem [56] documented TiO₂’s utility in hemodialysis systems,

improving water quality by removing microbial contaminants. Makowski and Wardas [57] reinforced the role of TiO₂ in microbial load reduction for drinking water applications. Shiraishi and Matsumoto [61] explored TiO₂’s application in hemodialysis water purification, noting its effectiveness in removing microbial byproducts like endotoxins. Lastly, Tiwari and Sharma [43] (2023) emphasized TiO₂’s role in achieving substantial reductions in microbial counts and maintaining water quality, mirroring this study’s findings. Collectively, these studies validate the treatment method’s effectiveness and its broad potential in water purification. This study’s findings have significant real-world implications. The demonstrated reduction in microbial loads highlights the potential application of the treatment in critical sectors like hemodialysis water systems and healthcare settings, where water purity directly impacts patient safety. Additionally, this approach can enhance public health outcomes in regions with limited access to advanced water treatment facilities. The manageable pH range after treatment supports its application in drinking water systems, aligning with global water safety standards.

Consequently, endotoxin levels ( Table 3 ) showed significant improvement after TiO₂ nanoparticle-based dialysis water purification process. The most significant reduction was observed in the UT sample, which decreased from 1.97 to 0.26 EU/ml, equivalent to an 86.8% reduction. BT and LT samples showed similar improvements with reductions of 86.0% and 83.6%, respectively, represented in Figure 9 . While showing less dramatic improvement, the tap water sample still achieved a 62.0% reduction from 3.95 to 1.50 EU/ml.

The TiO₂-based microporous filter demonstrated effective pH regulation, consistently adjusting water samples to values within the AAMI/ISO standards of 6.5-7.5. The tap water sample showed the most significant improvement, with its pH reduced from 8.2 to 7.4 ( Figure 10 ). This consistency throughout the filtration process underscores the filter’s reliability in maintaining optimal pH levels, a critical parameter for applications such as dialysis water treatment. The effectiveness of the filter is likely due to its ability to integrate multiple purification mechanisms, including photocatalytic degradation, adsorption of metal ions, and physical filtration through a well-optimized pore structure. The superior performance of the TiO₂-based filter can be attributed to the synergistic actions of its mechanisms. Photocatalytic degradation, powered by TiO₂ nanoparticles, breaks down organic contaminants, while metal ion adsorption enhances water quality by removing impurities. Additionally, the microporous design ensures efficient physical filtration. Together, these mechanisms contribute to significant reductions in chemical and biological contaminants, supporting the potential of this system as an additional purification step in dialysis water treatment facilities. This aligns with findings by Rincón & Pulgarin [62] and Wei & Yang [58] , who highlighted TiO₂’s efficacy in hemodialysis water systems and its role in achieving high purification standards. The results also align with Araña & Pulgarin [54] and Makowski & Wardas [57] , who emphasized the ability of TiO₂ to stabilize pH while effectively removing contaminants in drinking water applications. Furthermore, Elshafie & Ghanem [56] documented TiO₂’s role in improving dialysis water quality by targeting metallic impurities and pH optimization. Liu et al. [59] and Kaur et al. [47] further underscore advancements in TiO₂ nanotechnology, linking these innovations to improved performance in healthcare and water treatment environments. These findings have significant real-world implications, as it demonstrated the ability to regulate pH and remove contaminants positions TiO₂-based filtration systems as a cost-effective, scalable solution for healthcare facilities, particularly for dialysis water systems. The results also complement previous research on TiO₂’s multifunctionality, as reported by Carey & Oliver [60] and

Selma & Pacheco-Moisés [63] . Future applications could extend beyond dialysis to include broader water treatment and environmental remediation efforts, aligning with global public health goals and sustainability practices.