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TroyPhotocatalytic
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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 stirring 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!!!
"15 mL of tetrabutyl titanate (TBT) was added into 15 mL of
trifluoroacetic acid solution (50 wt.%) at room temperature. After stirring 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!!!
