A Comparative Study in the Design of TiO2 Assisted Photocatalytic Coatings Monitored by Controlling Hydrophilic Behavior and Rhodamine B Degradation


This work presents a comparative study related to the photocatalytic efficiency associated with wettability measurements and organic dye degradation, as well as other relevant properties (i.e., corrosion resistance, roughness, wettability, and adhesion to a substrate). The photocatalytic precursors are titanium dioxide nanoparticles (TiO2 NPs) which are dispersed onto a polymeric electrospun fiber matrix by using three different deposition techniques such as electrospraying, spraying, and dip-coating, respectively. In
this work, the host electrospun matrix is composed of poly(acrylic acid) fibers crosslinked with cyclodextrin
(β-CD), which shows a good chemical affinity and stability with the other deposition techniques which are responsible for incorporating the TiO2 NPs. In order to evaluate the efficacy of each coating, the resultant photocatalytic activity has been monitored by two different tests. Firstly, the reduction in the water contact angle is appreciated, and secondly, the degradation of an organic dye (Rhodamine B) is observed under UV irradiation. In addition, the final roughness, adherence, and pitting corrosion potential have also been controlled in order to determine which solution provides the best combination of properties. Finally, the experimental results clearly indicate that the presence of TiO2 NPs deposited by the three techniques is enough to induce a super hydrophilic behavior after UV irradiation. However, there are notable differences in photocatalytic efficiency on the Rhodamine B as a function of the selected deposition technique.

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A2.2.3. Spraying Process
As previously mentioned, similar parameters were adjusted for the spraying process.
The solution of TiO2 was pumped with a flow rate of 2 mL/h, with a distance of nozzlesample of 20 cm and for about 30 min of deposition (Spr sample). The spraying was performed by an ND-SP Precision Spray Coater (Nadetech Innovations, Noáin, Spain).

2.2.4. Dip-Coating Process
The dip-Coating process was carried out by ND-R Rotatory Dip-Coater (Nadetech
Innovations). Electrospun fiber mat samples were immersed into the CTAB-TiO2 solution
for a total time of 30 min. Immersion velocity was 500 mm/min, whereas the withdrawal
velocity of the robot was 200 mm/min, respectively (Dip sample).

Keywords: Photocatalysis; Wettability; Electrospraying; Spraying; Dip coating.