Green Synthesis of Titanium Dioxide Nanoparticles: Physicochemical Characterization and Applications: A Review

Abstract

Nanotechnology is an emerging field in science that exhibits significant promise in the synthesis of nanomaterials for diverse applications. Traditionally, these nanomaterials were manufactured using hazardous and labor-intensive physical and chemical processes. Nevertheless, in recent years, researchers have developed safer, more scalable, and environmentally friendly methods for green synthesis. The problem addressed in this study is the need for an environmentally friendly and efficient synthesis process for titanium dioxide nanoparticles (TiO₂ NPs) with enhanced properties. The aim of this work is to describe the synthesis of TiO₂ NPs with various plant extracts using a green approach and to evaluate the physicochemical characteristics and potential applications of the resulting nanoparticles. This study focuses on understanding how the integration of plant extracts influences the properties of TiO₂ NPs, particularly in terms of their structural, optical, and functional characteristics. The novelty lies in the use of plant extracts as bio-reductants and capping agents, which not only provides a safer and more sustainable synthesis method but also enhances the functional properties of TiO₂ NPs. This green synthesis approach reduces the use of harmful chemicals, making the process more environmentally friendly and economically viable, with potential applications in photocatalysis, antibacterial, and antioxidant activities. The TiO₂ NPs possess diverse functionalities, including photocatalysis, antibacterial properties, and antioxidant properties. The initial precursor, such as a metal salt, undergoes transformation into the desired nanoparticles through the actions of plants exactly. Bio-reduction and capping processes are carried out by secondary metabolites found in bacteria and plants. The results demonstrated that the plant extract-mediated TiO₂ NPs exhibited enhanced photocatalytic activity, superior antibacterial effects, and higher antioxidant potential compared to chemically synthesized TiO₂ NPs. This highlights the potential of green synthesis methods in producing nanomaterials with improved functional properties for a wide range of applications.

Keywords: eco-friendly remediation; green chemistry; pollutant degradation; sustainable environmental solutions.

Figure 4

Possible reaction mechanism for the formation of biosynthesized TiO₂ NPs from different Ti precursors ((A): Titanyl hydroxide, (B): TTIP, and (C): TiCl₄) [69].

Figure 4

Possible reaction mechanism for the formation of biosynthesized TiO₂ NPs from different Ti precursors ((A): Titanyl hydroxide, (B): TTIP, and (C): TiCl₄) [69].

Figure 1

Potential applications of TiO₂ nanoparticles in various fields of life.

Figure 2

Synthesis approaches, such as chemical, physical, and green methods.

Figure 3

Illustration of TiO₂ green synthesis and its applications.

Figure 5

FT-IR absorption spectra of chemically synthesized TiO₂-NPs (A)—(T1), (B)—(T2), and (C)—(T3) are synthesized by the plant extracts of T. portulacastrum and C. quinoa, respectively. Reprinted with permission from ref. [76] with permission of Elsevier.

Figure 5

FT-IR absorption spectra of chemically synthesized TiO₂-NPs (A)—(T1), (B)—(T2), and (C)—(T3) are synthesized by the plant extracts of T. portulacastrum and C. quinoa, respectively. Reprinted with permission from ref. [76] with permission of Elsevier.

Figure 6

SEM and EDX spectrum of (a) Ceaspina pulcherrima flower, (b) Nervila aragona leaf, and (c) Manihot esculante peel extract TiO₂ NPs. Reprinted from ref. [52].

Figure 7

XRD pattern of green synthesized TiO₂ NPs with JCPDS card. Reprinted with permission from [82], with permission of IOP publisher.

Figure 8

XRD of TiO₂(1), TiO₂(2), and TiO₂(3) at different T. violacea bulb extract volumes of 10, 20, and 40 mL, respectively. Reprinted with permission from ref. [58] with permission of Elsevier.

Figure 9

Antimicrobial activity of Trigonella foenum-graecum derived TiO₂ NPs against different microorganisms depicting zones of inhibition of (a) positive control, (b) TF-TiO₂ NPs, and (c) dimethyl sulfoxide control. Reprinted with permission from ref. [56], with permission of Elsevier.

Figure 10

Antibacterial action mechanism of TiO₂ NPs.

Figure 11

Simplified diagram illustrating the fundamental principles of semiconductor photocatalysis.