TiO2 Photocatalyst to replicate making a photocatalytic PVA film

  • Thread starter TroyPhotocatalytic
  • Start date
In summary, the conversation focused on the benefits of implementing a new project management software. The benefits included increased efficiency, better communication, and improved organization. The team also discussed the importance of training and support for a smooth transition to the new software. Overall, the group agreed that the new software would greatly benefit their organization.
  • #1
TroyPhotocatalytic
1
0
Hi photocatalytic experts, I've recently at home tried to replicate making a photocatalytic PVA film as outlined below (taken from the research undertaken by Lin, et al in a number of publications. A summary of the method was as follows:
"15 mL of tetrabutyl titanate (TBT) was added into 15 mL of
trifluoroacetic acid solution (50 wt.%) at room temperature. After stir￾ring for 3 h, a transparent solution was obtained. Then the solvent was
removed through a rotary evaporator. Finally, yellowish titania xerogel
was obtained.
0.125 g of titania xerogel and 0.5 g of PVA were dissolved into 16 mL
of deionized water, respectively. Subsequently, the above prepared two
solutions were mixed together under stirring and then transferred into
a 40 mL Teflon-lined autoclave, which was heated to 150 °C for 3 h.
After cooling down to room temperature, the solution was poured out
to a plastic dish and formed the PVA/TiO2 nanocomposite films."I wanted to use this film in combination with formic acid (a hole scavenger) to reduce NO3- from an aqueous solution via the formation of carboxyl radicals.The film looked good when done (I made up 4 Petri dishes of it). One I used with methylene blue to see if it would speed up decolourisation under sunlight but there was no improvement in speed over another Petri dish with no tio2/PVA (sun bleaching was more effective so I guess no OH radicals were created)?The second test I added water with 400mg/L of NO3- to a Petri dish, added formic acid at a molar ratio of 3:1 FA to NO3- and irradiated with 365nm 18W UV light. After 2 hours the NO3- was 650mg/L!!! Tested with a Horiba ionic NO3- Meter.So my questions are:
- did I do something wrong in my prep? I copied the steps to the letter though. I used one of those steel 100mL autoclaves with the Teflon inner container that goes in the oven. I cooked it for 3hrs at 150 degrees. I dried the meshed at 60 degrees C in a dehydrator overnight. There should be anatase crystals right?- how could the NO3- levels go up? I measured my pre sample after putting in the formic acid (pH was 3.6). If there was anatase, with a hole scavenger and low pH, it should have been converted to N gases. What could have happened?Any thoughts would be much appreciated. This is a hobby of mine and I wanted to make something cool for my fish tank. I have a science background and degree so happy for technical answers or questions. I understand the NO3- reduction pathways and possibility of making ammonia. I understand the difference between photolysis and photocatalysis and how hydroxide and carboxyl radicals are formed and recombine, etc.Please help!!!
 
Chemistry news on Phys.org
  • #2
It is possible that the photocatalytic PVA film that you made may not be effective in reducing NO3- from an aqueous solution. The main reason for this could be that the TiO2 particles in the film may not be in the right form or size to be able to generate the required amount of hydroxyl radicals. Generally, TiO2 particles need to be in anatase form and of nanometer size to be able to generate the required amount of hydroxyl radicals. Furthermore, the film also needs to have a good contact with the solution in order for it to be effective. It is also possible that the pH of the solution was too low for the photocatalytic process to be effective. It is also possible that there could have been some contamination in the samples that caused the NO3- levels to increase. Contaminants such as organic compounds or metals can act as electron donors and thus lead to an increase in the NO3- levels. To determine if this is the case, you can perform an elemental analysis of the sample using ICP-MS. To further investigate the issue, it would be helpful to perform a few more tests with different concentrations of TiO2 and/or pH to find out the optimal conditions for the photocatalytic reduction of NO3-. It would also be helpful to measure the amount of hydroxyl radicals generated during the reaction. This can be done using a fluorescence technique such as luminol. I hope this helps!
 

1. What is TiO2 and how does it act as a photocatalyst?

Titanium dioxide (TiO2) is a naturally occurring oxide of titanium that is widely used as a white pigment in various applications. As a photocatalyst, TiO2 utilizes the energy from ultraviolet (UV) light to initiate chemical reactions. When UV light is absorbed by TiO2, it generates electron-hole pairs that can break down organic pollutants and bacteria, and also decompose water molecules, making it highly effective for applications like air purification, water treatment, and self-cleaning surfaces.

2. How can you make a photocatalytic PVA film using TiO2?

To create a photocatalytic polyvinyl alcohol (PVA) film incorporating TiO2, you typically start by preparing a TiO2 nanoparticle suspension. This suspension is then mixed into a PVA solution. The mixture is stirred to ensure uniform distribution of TiO2 particles within the solution. Afterward, the solution is cast on a suitable substrate and allowed to dry, forming a thin film. This film can then be used as a photocatalytic coating on various surfaces to harness the properties of TiO2 under UV light exposure.

3. What are the key benefits of using a TiO2-PVA photocatalytic film?

The TiO2-PVA photocatalytic film offers several benefits including air purification, antibacterial properties, and self-cleaning surfaces. The film can effectively degrade organic pollutants and pathogens upon exposure to UV light, making it ideal for environmental cleanup and hygiene applications. Additionally, the film can reduce the maintenance required for surfaces as it helps in decomposing dirt and other organic materials, keeping surfaces cleaner for longer periods.

4. What are the challenges in developing and using TiO2-PVA photocatalytic films?

One of the main challenges is the efficient activation of TiO2 under sunlight, as it primarily responds to UV light, which constitutes a small fraction of natural sunlight. Developing TiO2 variants that can activate under visible light is an area of ongoing research. Additionally, the durability and longevity of the photocatalytic activity when embedded in PVA films can be a concern, requiring enhancements in film formulation and processing techniques to ensure sustained activity and stability under various environmental conditions.

5. Are there any environmental concerns associated with using TiO2 in photocatalytic applications?

While TiO2 is generally considered non-toxic and environmentally benign, there are concerns about the potential impact of nano-sized TiO2 particles if they are released into the environment. Research is ongoing to fully understand the ecological impacts of nanoparticles, including their toxicity to aquatic life and potential to accumulate in the food chain. Proper handling and disposal methods, as well as thorough assessment of environmental safety, are essential when deploying such materials on a large scale.

Hot Threads

Recent Insights

Back
Top