Photodegradation of Air and Water Contaminants Using 3D-Printed TiO₂ Nanoparticle Scaffolds

Abstract

A significant challenge in the photocatalysis field is getting selfsupporting three-dimensional (3D)-printable photocatalysts that preserve their photocatalytic activity. Herein, we disclose reusable 3D-printable photocatalysts based on binder-free TiO 2 nanoparticles (3DM-TiO 2 ) under an eco-friendly, affordable, and reliable methodology for the first time. Strong and mechanically stable 3DM-TiO 2 structures (compression strength = 16 MPa) were obtained under soft sintered conditions (∼400 °C), exhibiting an anatase/rutile ratio of 85/ 15% by the Rietveld refinement, a mesoporous structure with a surface area (S BET ) of 45.2 m 2 /g, and outstanding photocatalytic activity. 3DM-TiO 2 successfully demonstrated high recyclability and adaptability in the dust-free photodegradation experiments of emerging contaminants in the liquid phase (triclosan, TCS) and gas phase (liquefied petroleum gas, LPG). A TCS mineralization of ∼95% was obtained at 6 h of photodegradation. The reusability from the 3DM-TiO 2 was assessed during 12 cycles of TCS degradation, recovering its photocatalytic activity by 100% after reactivation at 400 °C. In the gas phase, the maximum conversion of LPG to CO 2 was 95.3% for n-butane, 93.7% for isobutane, and 52.9% for propane after 15 h of photodegradation. All photodegradation experiments were fitted to the Langmuir−Hinshelwood kinetic model. We believe that the technology proposed here could trigger applications of nanomaterial-based photocatalysts, replacing the powdered materials to achieve new reactor designs and process configurations on a large scale.

The Aging of Polymers under Electromagnetic Radiation

“…UV radiation deteriorates plastic waste components, accelerating their rate of aging [ 132 , 133 , 134 ]. Likewise, previous research by Ávila-López et al [ 135 ] and Cacuro et al [ 136 ] acknowledged that many polymeric materials are vulnerable to UV radiation because the overall energy of UV radiation supersedes the strength of the inherent carbon bonds in polymers. Concurrent perspectives from Garg et al [ 137 ], Lei et al [ 138 ], and Palkar et al [ 139 ] indicate that electromagnetic radiation from a UV source can fracture a polymer and reduce its molecular weight, leading to the generation of free radicals.…”

3D direct ink printed materials for chemical conversion and environmental remediation applications: a review

“…This new trend of technological tailormade developments allowed users to obtain more specic materials, simplifying their design and application in complex reactor systems, and increasing their efficiency or equalling the photocatalytic activities of their powdered counterpart. 101 A good photocatalytic material should involve a good charge separation, a fast charge transfer, absorption in the visible light spectrum of the UV-Vis range, high stability, low cost, and nontoxicity. 94 Hence, the development of photocatalytic 3D printed materials should take into account all these properties.…”

“…This new trend of technological tailormade developments allowed users to obtain more specific materials, simplifying their design and application in complex reactor systems, and increasing their efficiency or equalling the photocatalytic activities of their powdered counterpart. 101…”

“…The SLDD manufactured TiO 2 showed 99% and 79% removal of 20 mg L −1 of ACE in solution within 60 min of UV-vis irradiation by using 0.5 and 22 g L −1 of TiO 2 in slurry and SLDD form, respectively. 105 Meanwhile, Ávila et al fabricated the three-dimensional structures from TiO 2 nanoparticles using a mixture of volumetric ratios of water and glycol 50 : 50, and subsequently dried at 400 °C for 6 h. 101 The binder-free monoliths were evaluated for the photodegradation of triclosan in liquid phase and light-weight hydrocarbons in gas phase. The 3D printed square-lattice monoliths shown 99.5% of triclosan photodegradation and >90% of total organic carbon mineralization after 240 min under UV-Vis LED light irradiation.…”

Encapsulation of TixFeyLamOz nanoparticles into NH2-MIL-125(Ti) to fabricate a promising photocatalyst for the C–N coupling reaction

“…[4][5][6][7][8][9][10] TiO 2 has been frequently investigated, and it has become the most promising photocatalyst to use in organic reactions due to its high efficiency, high photocatalytic activity, nanotoxicity, cost-effectiveness, and chemical stability. [11][12][13][14][15] Nevertheless, because of the wide band gap of pristine titanium dioxide (TiO 2 ), it is inefficient for carrying out reactions under visible light. 16 To produce a photocatalyst with the ability to operate under visible light, different methods exist, among which doping TiO 2 with metals can transfer the active area of TiO 2 from ultraviolet light to visible light.…”