Synthesis and Characterization of Silver-Doped TiO₂ Nanocomposite Using Diethanolamine as Solvent: Photocatalytic Performance for Organic Dye Degradation and Antimicrobial Activity

Abstract

In this research work, Ag-doped and undoped TiO₂ nanocomposites were prepared through a sol–gel method, using diethanolamine as a solvent. From the evolution of various characterized techniques (XRD, FT-IR, SEM and TGA analysis), it was found that Ag-TiO₂ nanocomposites have a mixture of rutile and anatase phases of titania. The catalytic performance of the Ag-TiO₂ nanocomposites was evaluated for Eriochrome Black T (EBT) photodegradation. To determine the photocatalytic efficiency of the nanocomposites, different factors including pH (2–12), catalytic dose (2–12 mg), reaction time (0–180 min) and concentration (2–10 mg/L) were investigated. The calcined Ag-TiO₂ showed high degradation (94%) for EBT at a low pH for 0.01 g of catalyst using 10 mg/L of dye solution. The kinetic study revealed that the photocatalytic degradation process obeys pseudo second-order kinetics. To investigate antibacterial effects, different bacteria such as Enterococcous, Staph Avrius, serritia and Escherichia E. coli were utilized. A total of 200 mg of calcined Ag-TiO₂ nanocomposite showed optimum activities against bacterial strains.

1. Introduction

Numerous studies have been conducted on titanium dioxide because it has attracted the attention of researchers in recent decades due to its high photocatalytic potential, thermal stability, non-toxicity, low cost, and ease of preparation [1]. It can be used in different fields such as for efficient self-cleaning surfaces, air purification, pigments and the conversion of harmful organic pollutants to carbon dioxide in water. It also shows superiority against different bacterial strains when exposed to light. TiO₂ exists in three crystalline phases: anatase, brookite and rutile [2]. TiO₂ in rutile phase is more stable than that in anatase or brookite phase at normal temperature [3]. The anatase phase of the TiO₂ crystalline structure has excellent photocatalytic activity potential, while the crystalline composition of the rutile phase has the highest refractive index and greater stability. The rutile phase of TiO₂ has direct band gap semiconductors with an optical band edge of 3.06 eV, while the anatase phase of TiO₂ contains an indirect band gap with an optical band edge of 3.20 eV [4]. The anatase phase of TiO₂ shows strong antibacterial properties, which has resulted in it attracting great attention due to its inactivation of bacterial cells, while the anatase phase is regarded as the most photochemically active phase of titanium dioxide [5]. Under UV light, TiO₂ has good photodegradation, antibacterial and antiviral properties because the UV region of electromagnetic radiation can excite electrons between the valence band and the conduction band. However, only 5% of UV light reaches earth as this light is absorbed by different atmosphere layers. This low concentration limits TiO₂’s practical application in industry and daily life [1,3]. To synthesize TiO₂ photocatalyst that is active in visible light, the absorption band gap of TiO₂ can be modified by different preparation protocols. This target can also be achieved by doping TiO₂ with non-metals (S, B, N, etc.), transition metals (Fe, Cr, Ag, etc.), and semiconductors with small band gaps [2,6]. Nobel metals have the potential to be used in the photocatalytic process by capturing the charge species and preventing recombination of electrons and holes, enabling the generation of electron excitation by a local unit cell electric field [6]. The ability of TiO₂ to photocatalyze different pollutants is dependent on the production of electron–hole pairs when it is exposed to light. Silver nanoparticles (AgNPs) are one of the most attractive metals to dope onto TiO₂ due to their improved photocatalytic and antibacterial effects. Unlike antibiotics, AgNPs have been extensively investigated because of their wide range of antibacterial behavior against both Gram-positive and Gram-negative bacteria [7]. Additionally, the high specific surface area of AgNPs makes it easier to discharge silver ions (Ag⁺), which kill different strains of bacteria [8]. Different supported biosynthesized AgNPs have been shown to have enhanced photodegradation as well as antibacterial properties [9,10]. As aforementioned, that anatase phase of TiO₂ is the metastable state. However, it can be stabilized by using different preparation methods such as using a high annealing temperature or different organic solvents. Previously, 100% anatase-phase TiO₂ with high photocatalytic activities was prepared in basic media using ethanol as a solvent [11], while in our previous studies, a mixture of rutile and anatase phases of titania was synthesized in diethanolamine solvent and achieved greater antibacterial properties [12]. Therefore, in this research, we designed and synthesized silver-doped anatase-phase TiO₂ using diethanolamine as a solvent. Furthermore, the antibacterial and photodegradation properties of the synthesized silver-doped anatase-phase TiO₂ were investigated. To our knowledge, simultaneous degradation of Eriochrome Black T (EBT) and antibacterial activity have not yet been accomplished using Ag-doped TiO₂ nanocomposite.

2. Results and Discussion

2.1. Physical Characterization of Ag-TiO₂ Nanocomposite

Figure 1 demonstrates the FTIR spectra of uncalcined and calcined pure and TiO₂-supported silver nanocomposites within the range of 500–4000 cm⁻¹, which were used for the identification of the different moieties present in the Ag-TiO₂ nanocomposites. The broad band that was observed in these spectra at wavelengths of 3453, 3430, and 3418 cm⁻¹ certified the O-H stretching vibration [13]. In uncalcined Ag-doped TiO₂ nanocomposite, the band at 1609 cm⁻¹ represents the O-H bending vibration [13]. These groups are formed as a result of chemically adsorbed water molecules in the nanocomposite. The broad peaks appearing at 450–830 cm⁻¹ correspond to Ti-O bending vibrations, confirming metal–oxygen bonding in the nanocomposite [14]. The broad bands seen at 2949 and 2853 cm⁻¹ were matched to C-H vibration due to the use of diethanolamine and sodium citrate as the solvent and for gel formation respectively. Similarly, the peaks appearing at 3257 cm⁻¹ for uncalcined Ag-TiO₂ are due to N-H stretching. This result indicates that diethanolamine, which was used as a solvent for the preparation of Ag-TiO₂, is observed in the FTIR result. The peak for diethanolamine disappeared for the calcined Ag-TiO₂ nanocomposite. The appearance of new peaks from 600 cm⁻¹ to 800 cm⁻¹ indicates the doping of silver on the TiO₂ nanocomposite. Meanwhile, Ag-TiO₂ nanoparticles showed characteristic bands at 2966, 2938, 2371, 2111, 1635, 1462, 1397, 1071, 1059, 663, and 606 cm⁻¹ [15].

The TGA curves of Ag-TiO₂ uncalcined and calcined up to 1000 °C are shown in Figure 2. From the TGA of the calcined Ag-TiO₂ curve, it is clear that weight loss occurred in three stages. The first weight loss from 80 °C to 103 °C might be due to physically adsorbed water molecules. However, the change in weight from 103 °C to 600 °C may be ascribed to the removal of organic resides from the nanocomposite. About 2.83% weight loss took place between 600 and 700 °C. This change in weight is due to the transformation of TiO₂ from one form to another phase in this temperature range as reported in the literature [9,16]. The total weight loss from the calcined Ag-TiO₂ was 27.72% up to 1000 °C. The TGA profile of the uncalcined nanocomposite showed that from 30 to 200 °C, 50% weight was lost. The literature suggests that the first change in weight is due to the evolution of moisture from the catalyst. The second weight loss from 280 °C to 460 °C was matched to the decomposition of trisodium citrate and diethanolamine, which were used in the preparation of the nanocomposites. These wight loss are different in calcined (black arrow) and uncalcined samples (red arrow). In the literature, this weight loss is matched with rearrangement of the different polymorphic rutile–anatase transformations of TiO₂ and the decomposition of AgNO₃ [17].

The prepared nanocomposites were investigated by XRD, the results of which are displayed in Figure 3. This analysis was carried out to evaluate the phases of the uncalcined and calcined nanocomposites. The XRD pattern for the uncalcined sample (Figure 3, red color) clearly indicates that pure titanium oxide in the uncalcined form is amorphous. When pure titanium oxide is doped with silver nanoparticles prepared using triethylamine solvent, different types of peaks appear in the powder XRD patterns (Figure 3, blue color). The peaks appearing at 2θ positions of 54.68°, 25.72° (JCPDS card No. 01-075-1537), and 37.23° (JCPDS card No. 01-071-1169) show the anatase phase of TiO₂ [18]. Also, the peaks arising at 2θ positions 27.75° (JCPDS card No. 01-082-0514) and 69.09° (JCPDS card No. 01-078-1510) show the rutile phase of TiO₂ [19]. The Ag₂O peak appears at a 2θ position of 24.34° (JCPDS card No. 01-076-1393). These results indicate that silver doping onto TiO₂ causes the conversion of TiO₂ into a crystalline form at low temperature (as more obvious from the pattern in Figure 3). Also, a mixture of rutile and anatase phases is formed due to the doping of silver onto TiO₂. The XRD pattern (Figure 3, black color) of Ag-TiO₂ nanocomposite reveals the presence of anatase phase with characteristic bands at 2θ positions of 25.41°, 36.76°, 38.08°, 41.33°, 48.25°, 56.67°, and 62.86° (JCPDS card No. 01-084-1286). Also, the peaks appearing at 2 theta positions of 32.33°, 33.96° and 37.94° (JCPDS card No. 01-074-1743) show the presence of Ag nanoparticles, while the peak at two theta 27.49° (JCPDS card No. 01-082-0514) certifies the rutile phase in the silver-doped TiO₂ nanocomposite [20]. The XRD peaks for uncalcined silver-doped TiO₂ nanocomposite (b) at 2θ positions of 27.49°, 36.13°, 54.35°, 56.67°, and 69.1° (JCPDS card No. 01-073-1765) show the rutile phase, while the peaks at 2θ positions 25.35° and 46.45° (JCPDS card No. 01-083-2243) show the anatase phase.

To investigate the surface morphology of the synthesized nanocomposites, SEM images were used. A SEM image of the TiO₂ nanocomposite is depicted in Figure 4a. The figure clearly indicates that particles of TiO₂ were irregularly dispersed in shape and size, and some were in an agglomerated form [21]. The doping of silver disintegrated the particles. Small, spherical particles formed on the surface of large particles (Figure 4b). The SEM images demonstrated that there was no aggregation in the silver-doped titanium dioxide nanoparticles, and they were evenly dispersed on the surfaces. On calcination, Ag-TiO₂ nanocomposites transformed to the flower-petal-shape structure (Figure 4c) [22]. These results indicate that calcination of Ag-TiO₂ using diethanolamine as the solvent changes both the phase and shape of the prepared nanocomposites.

2.2. Degradation Studies of EBT Using Ag-TiO₂ Nanocomposite

2.2.1. pH Effect

The impact of pH on the degradation process is particularly significant since the surface charge of the photocatalyst is a function of pH and because the dye structure changes with the pH of the EBT solution. The photocatalytic efficiency of EBT dye was studied at various pH values from pH 2 to 12 under sunlight. Figure 5 displays the pH effect of 8 mg/L of dye solution at room temperature and a catalyst dose of 0.01 g. The solution was maintained for 60 min at room temperature. The figure shows that degradation of EBT dye decreased from 99.37 to 58% with increasing pH of the dye solution from pH 2 to pH 12. This behavior shows that EBT has an anionic composition, because sulfonate groups, i.e., negatively charged groups, are present (Figure 6) [23]. The catalyst’s surface becomes positively charged in acidic pH, which enhances the degradation of the dye due to electrostatic interactions. However, as the pH rises, less interaction occurs between the nanocomposite surface and dye molecules, which causes decreased degradation of the dye [24]. At pH 2, the dye degradation was maximum, and this was therefore selected as the optimum pH.

2.2.2. Effect of Dose

The influence of the photocatalyst dosage was investigated using 2–12 mg of catalyst at pH 2 and 8 mg/L concentration of EBT as given in Figure 7. The data obtained regarding photocatalytic degradation showed that, when the amount of catalyst was increased from 2 to 12 mg, the photodegradation of the dye increased from 91.51 to 99.00%. This increased performance revealed that active binding sites were present on the catalyst surface which carried out the photodegradation of EBT molecules in solution. As the amount of Ag-TiO₂ nanocomposites increased, photodegradation of the EBT dye increased. However, after 10 mg of nanocomposites, the degradation of the EBT dye remained constant. This result indicated that 10 mg had sufficient sites for the degradation of 8 mg/L of EBT solution, and a further increase in nanocomposites has no significant influence on the degradation percentage of EBT. Similar results were obtained in a previous investigation [25].

2.2.3. Effect of Contact Time

The degradation percentage of dye from solution was investigated using contact times (0–180 min). Figure 8 shows the dye degradation using 0.01 g of catalyst at pH 2 and an 8 mg/L dye solution concentration. It demonstrates that the degradation increased initially and obtained an equilibrium position in the initial 100 min. These results clearly indicate that the time required to completely occupy all the binding sites for the degradation of EBT on the given nanocomposite was 100 min. Further passage of time had no significant influence on the degradation of EBT. So, with further increases in the contact time, the dye degradation was stable, which lowered the coupling chance of the dye and catalyst [26]. It was observed that at the equilibrium position the maximum amount of dye degradation was 99.86%. At equilibrium the prepared Ag-TiO₂ nanocomposite showed greater degradation of dye as compared to that observed in previous studies [27].

2.2.4. Effect of Concentrations

To determine photocatalytic efficiency as a function of the dye concentration, different concentrations of EBT (2 mg/L, 4 mg/L, 6 mg/L, 8 mg/L, 10 mg/L) and 0.01 g of catalyst were used as communicated in Figure 9. The results obtained from various concentrations revealed that the degradation percentage of the EBT dye increased from 61% to 94% with enhancement of the dye concentration from 2 to 12 mg/L. This means that photodegradation is a surface mechanism that is directly dependent on the active binding sites available on the surface of the Ag-TiO₂ nanocomposite. Degradation of dyes also occurs due to the formation of OH radicals on the catalyst’s surface. The catalyst dosage was kept constant throughout these studies. So, the amounts of hydroxyl radicals on the prepared nanocomposite were fixed while the concentration of the dye increased. Therefore, the degradation percentage of the EBT dye was increased [24]. The high activity of Ag-TiO₂ is due to the coexistence of anatase and rutile phases in the prepared nanocomposite, where the interfacial phase junctions work as a mediator for photogenerated charge separation and suppress recombination [28,29]. Compared with pure anatase reported in the literature, such mixed-phase TiO₂ often shows improved photocatalytic activity due to synergistic interphase electron transfer and slightly enhanced light harvesting. In the Ag-TiO₂ system, silver doping further strengthens this effect by trapping electrons and promoting reactive oxygen species formation. From the above discussion we may elaborate the photodegradation of EBT on Ag-TiO₂ in Figure 10.

2.2.5. Acid Tolerance Test

Different types of acid (i.e., HCl and H₂SO₄) were added into 0.08 mg/L dye solution to study their effects on the degradation of dyes as shown in Figure 11. Initially the degradation percentage of dye solution containing acid, i.e., HCl or H₂SO₄, was higher. However, as the acid amount was enhanced, the dye degradation in solution decreased since higher acid concentrations may destroy the active sites present on the surface of the prepared nanocomposite. So, the number of available moieties decreased and, therefore, with both acids the catalytic activities of the nanocomposite diminished.

2.2.6. Kinetic Studies of Dyes

The degradation rate of dye in solution on the surface of the catalyst was investigated by pseudo first- (PFO) and second-order (PSO) kinetic models, and the results are plotted in Figure 12 and Figure 13. These kinetic models were applied to experimental data at various intervals of time [30]. The following Equations (1) and (2) were used in linear form to assess the kinetics of dye degradation.

$$ln(q_e-q_t)=ln{q}_e-{\displaystyle \frac{k_1}{2.303}}\times t$$

(1)

$${\displaystyle \frac{t}{q_t}}={\displaystyle \frac{1}{k_2{q}_e^2}}+{\displaystyle \frac{t}{q_e}}$$

(2)

In the above equations, q_e and q_t represent the amounts of dye degraded on the catalyst and at time t respectively. For PFO and PSO the rate constants are k₁ and k₂ respectively [31]. The results showed that EBT degradation on a photocatalytic surface follows the PSO model (R² = 0.99) more closely than the PFO model (R² = 0.86). In short, to summarize the photodegradation of EBT on Ag-TiO₂ the current results were compared with the recent literature, which is given in

Table 1. Comparison of dye degradation activity of different photocatalysts.

Photocatalyst	Dye	Light Source	Degradation (%)	Reference
Ag/Ti3C2/TiO2	Rhodamine B	Visible light (300 W)	97	[32]
TiO2/Ag	Acid orange 7	Visible light (300 W)	95	[33]
Ni; TiO2	EBT	UV/Vis	90	[34]
Bi2O3/TiO2	EBT	Visible light	76	[35]
Ag-TiO2	EBT	Visible light	94	Current study

[32,33,34,35]. The table clearly indicates that TiO₂-based photocatalysts reported in the recent literature exhibit strong activity toward the degradation of various model dyes under visible, simulated solar, or natural sunlight irradiation. The improved performance of TiO₂ with Ag is generally attributed to the plasmonic and electron-trapping role of Ag, which suppresses electron–hole recombination and promotes the formation of reactive oxygen species. In the present study, the Ag-TiO₂ nanocomposite also demonstrated efficient degradation of EBT under natural sunlight, confirming the suitability of Ag-modified TiO₂ for solar-assisted dye remediation.

2.2.7. Antibacterial Activity of Ag-TiO₂ Nanocomposite

The antibacterial effectiveness of pure TiO₂, Ag-TiO₂ (uncalcined) and Ag-TiO₂ (calcined) was evaluated against Staph Avrius, Escherichia E. coli, serritia and Enterococcous bacteria using the agar well disc diffusion method (Figure 14). The resulting zone was measured and recorded using a scale. Each experiment was repeated three times for four different bacterial strains, and the diameters of the zones of inhibition were measured in millimeters. Ciprofloxacin was used as a standard drug. It was found that pure and uncalcined Ag-TiO₂ showed no activity. However, calcined Ag-TiO₂ showed activity against the given bacterial strains. During calcination a mixture of rutile and anatase phases was formed, and a previous investigation found that the anatase phase is active against different bacterial strains. So, the current activities of the calcined Ag-TiO₂ nanocomposite may be due to the combined effect of anatase-phase TiO₂ and silver [2]. For further investigation, different concentrations of calcined Ag-TiO₂ (100, 150, 200, and 250 mg/L) were synthesized and tested against each bacterial strain, as shown in Figure 14. The figure displays that when the concentration of calcined Ag-TiO₂ nanocomposite was raised, the performance of the prepared nanocomposites against bacteria was improved. From the results it was found that 200 mg/L was the optimum concentration of Ag-TiO₂ which showed the highest activities. Silver ions from doped titanium dioxide gradually spread from the discs into the agar during incubation. From the literature it was found that silver ions interact with protein thiol groups, attach to cell membranes, and inactivate respiratory enzymes, resulting in the death of bacteria [36,37]. From previous investigations it was also found that reactive oxygen species, particularly hydroxyl radicals, inhibit the replication of DNA in bacteria and destroy bacterial outer membranes, resulting in phospholipid peroxidation and, eventually, cell death. Silver doped on TiO₂ operates as an electron-trapping site for photogenerated electrons. So, this method generates more hydroxyl radicals, providing better antibacterial results [38].

3. Materials and Methods

Titanium dioxide (TiO₂) from BDH Limited Pool England GPR (Poole, UK); trisodium citrate and diethanolamine from E. Merck(Darmstadt, Germany); silver nitrate with 98% purity from Germiston Chemicals F.H., (Germiston, South Africa); distilled water (Frovit W4L, Puchong Selangor Darul Ehsan, Malaysia); ciprofloxacin; and nutrient agar (Oxide) were the chemicals used during this research project. Reagents such as silver nitrate (AgNO₃), ciprofloxacin, nutrient agar and trisodium citrate were purchased from Merck. Diethanolamine (C₄H₁₁NO₂) and titanium dioxide were obtained from Germany.

3.1. Preparation of TiO₂ and AgNPs

The sol–gel approach was used to prepare silver-doped titanium oxide nanoparticles. Initially, to 100 mL of diethanolamine, 1 g of TiO₂ was added and continually stirred for two hours. About 4 g of trisodium citrate was added into diethanolamine and stirred for one hour. The prepared solution of trisodium citrate was added dropwise into the TiO₂ solution and then stirred continuously while it was heated up to 300 °C for 20 h to remove solvents. After that, it was placed in a furnace at 500 °C for three hours for calcination. The calcined nanocomposite was ground and used for further studies. For the synthesis of silver nanoparticles, initially, a silver nitrate solution of 0.1 M was prepared. Then 30 mL of the silver nitrate solution was taken, and 7 mL triethylamine was added dropwise until a deep dark brown color appeared. The formation of the deep dark brown color indicated the formation of AgNPs. A Shimadzu UV–Vis spectrophotometer (Model: 8400S, Tokyo, Japan) was used to observe the conformation of the silver nanoparticles.

3.2. Preparation of Ag-TiO₂ Nanocomposites

To synthesize Ag-doped TiO₂, 15 mL of 0.1 M doped Ag nanoparticles were taken and sprayed into TiO₂ solution with continuous stirring, and then the prepared nanocomposite was heated on a hot plate with continuous stirring to remove the solvent. Then the nanocomposites were calcined for 2 h in a tube furnace at 500 °C in a nitrogen environment (20 mL/min). The temperature was lowered by 10 °C/min to room temperature, and then the sample was crushed to a particle size of 90 µm to 212 µm.

3.3. Characterization of Ag-TiO₂ Nanocomposite

SEM (FESEM, JEOL JSM-6701F, Tokyo, Japan) was carried out to investigate the surface morphology of the nanocomposites. X-ray diffractometer (Rigaku Co., Tokyo, Japan) was used in the range of 20–80° to investigate the crystallinity and phases present in the nanocomposites. The moieties of the prepared nanocomposite were evaluated by FTIR in the range of 4000–400 cm⁻¹ with a Thermo Optics Avatar 330 FTIR device (Thermo Fisher Scientific, Waltham, MA, USA).

3.4. Screening of Ag-TiO₂ Against Four Different Bacterial Strains

The prepared Ag-TiO₂ nanocomposite in both calcined and uncalcined form was screened against four different bacterial strains (Staph Avrius, Escherichia coli, Serritia and Enterococcous) using the agar well disc diffusion method. Nutrient agar was used as the medium in this method [39]. The equipment like the Petri plates, laminar flow hood, micropipette, sterile borer, flask, incubators, wire loops, and micropipette used in this experiment were autoclaved for 1 h up to 120 °C. About 20 mL of nutrient agar was poured into each Petri plate and left for some time to cool down. Then, to each nutrient agar Petri plate, bacterial strains were added. A wire loop was used to spread the bacterial strains in each Petri plate, and then the plates were left to solidify. With the help of a sterile borer of size 6 mm, 4 wells were punched in each Petri plate. To each Petri plate a 30 μm/L suspension of the prepared nanocomposite was then added in every bore. In one of the bores on each Petri plate, ciprofloxacin was added as a standard drug. After that, each plate was placed in an incubator for 24 h at 35 °C. Furthermore, each of the Petri plates was maintained in a laminar flow hood to avoid contamination. The zones produced were measured using a scale after 24 h to determine the zone of inhibition. The trials were repeated three times for each bacterial strain, and the zones of inhibition were measured in millimeters.

3.5. Degradation Experiments

To determine EBT dye degradation in the presence of sunlight, various experiments on the pH (2–12) effect, dose (2–12 mg) effect, time (0–180 min) effect and concentration (2–12 mg/L) effect were performed. After shaking, a sample was taken from the tube and then its absorbance was determined using a UV-Vis spectrometer (Shimadzu, 1800; Tokyo, Japan) at 557 nm. Then the EBT degradation percentage was determined using the formula below.

$$Percent degradation=(\left(A_o-A_t\right)/A_o)\times 100$$

(3)

In the above equation A_o and A_t represent the initial and finial absorbance of the dye in solution, respectively.

4. Conclusions

In this research work, Ag-TiO₂ nanocomposites were synthesized by the sol–gel method using diethanolamine as a solvent. From TGA analysis it was found that calcined Ag-TiO₂ nanocomposite was stable up to 900 °C, and small weight loss took place from the prepared sample. The XRD technique showed the coexistence of silver with a mixture of the rutile and anatase phases of TiO₂. SEM results showed that due to the evaporation of diethanolamine and trisodium citrate, a flower-petal-shaped nanocomposite of Ag-TiO₂ was formed. The prepared nanocomposites were used to study photocatalytic degradation and the viability reduction of bacterial activity. The calcined Ag-TiO₂ showed a high level of degradation for EBT at low pH, using 0.01 g of catalyst for 10 mg/L of dye solution. The equilibrium for degradation of the dye was achieved in the initial 100 min. The addition of acid had an adverse effect on the catalytic activities of Ag-TiO₂. Only the calcined Ag-TiO₂ reduced the growth of bacteria. Ag-TiO₂ nanocomposite at a 200 mg/L concentration achieved the optimum antibacterial activity for four different bacterial strains. So, the preparation of Ag-TiO₂ using diethanolamine as a solvent resulted in a mixture of anatase and rutile phases that showed high photodegradation and antibacterial activities.