The research we have conducted is not yielding any result despite following the proper protocol :
Titanium nanoparticles were synthesized, calcinated and stored under proper conditions.
To perform photocatalysis :
We added 0.05g of TiO2 nanoparticles, 0.5 ml hydrogen peroxide to a 50ml solution of methyl orange in a set of two beakers, stirred in the dark for half an hour to achieve the absorption - disorption equilibrium.
One beaker was kept under the UV light of biosafety cabinet since we do not have a photoreactor. But after 3 hours of irradiation, it did not degrade the dye.
The other beaker containing nanoparticles and methyl orange solution was irradiated using tungsten bulb with a distance of 5 cm on a constant stirrer for 3 hours.
But after 3 hours of exposure to light there was no sign of degradation.
We also tried balancing the pH by adding HCL dropwise to make make the solution Acidic so that methyl orange has a negative charge and titanium nanoparticles would carry a positive charge.
The experiment does not yield result in either of the above mentioned light sources. What are the factors that need to be changed or are missing for dye degradation to occur.
Faryal Iqbal
1. you did not write the size of the nanoparticles. Maybe you don't have nanoparticles.
2.The band gap of the TiO2 anatase crystal is Eg=3.2 eV. To provide the energy required for excitation, ultraviolet light with a wavelength of no more than 387.5 nm is required.
3.Methyl orange absorption peak 464 nm. You need to measure the absorbance at this wavelength to ensure dye degradation. It should decrease.
Article CHARACTERIZATION AND PHOTOCATALYTIC PROPERTIES OF TITANIUM D...
Use 0.1g minimum in pH optimization study. Try to provide UV light containing almost all intensity range upto 400nm .
•make sure the band Gap region by DRS
•if their is any washing step in the catalyst preparation . Repeat it several times .
• make sure you are using correct lambda max for absorption study.
• perform DRS and FTIR before study to ensure the synthesized product has a band gap in that region and has no impurities.
Can ask further . good luck ..
Thanks and regards
I have some ideas that may help:
-Hydrogen Peroxide Concentration: Choose a ratio where the H₂O₂ concentration is at least twice that of methyl orange. This will enhance the oxidation process.
-UV Light Source: Ensure you have information about your UV lamp, particularly its maximum emission wavelength. Compare this with the molar absorption spectrum of methyl orange, as a high molar absorption could cause it to act as a filter for photons.
-pH Considerations: Work around the point of zero charge (pHzc) of TiO₂, which is about 6.2. Research the pKa of methyl orange, as it is a pH indicator. -Start with a small concentration of dye may also be beneficial 5mg/,10mg/l ...ect .
When conducting photocatalysis of a dye solution using titanium dioxide (TiO₂) nanoparticles, several interconnected factors must be carefully controlled to achieve efficient degradation. The photocatalytic performance depends on the intrinsic properties of the TiO₂ catalyst, including its crystal phase (preferably anatase for higher activity), nanoparticle size (10-30 nm optimal for surface area), and potential modifications like doping with metals/non-metals or forming composites to enhance visible-light absorption. The dye solution characteristics such as initial concentration, pH (optimal range 3-5 for anionic dyes, 9-11 for cationic dyes), and temperature (25-50°C ideal) significantly influence the reaction kinetics. The illumination conditions require precise optimization of light wavelength (UV below 387 nm most effective for pure TiO₂), intensity, and exposure duration. Operational parameters like catalyst loading (0.1-1 g/L recommended), oxygen supply (aeration enhances superoxide radical formation), and continuous stirring are crucial for maintaining reaction efficiency. The presence of radical scavengers or interfering ions must be considered, as they can dramatically affect degradation pathways. Post-reaction analysis should evaluate both dye decolorization (UV-Vis) and complete mineralization (TOC analysis), while catalyst reusability tests assess practical applicability. Key challenges include minimizing electron-hole recombination through appropriate modifications, preventing catalyst leaching, and improving visible-light response through sensitizers or plasmonic enhancements. Each of these factors interacts complexly, requiring systematic optimization for maximum photocatalytic efficiency.
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