Further Effect of Photocatalysis toward organic particles size distribution

I have mentioned several information on my post about the effect of photocatalysis process to particle size distribution. Now in this post, I would like to a little bit further explain it more as I am really courious about this.

The picture below is sort of summary of what has being shown on previous post. It is about the effect of photocatalysis toward organic particles distribution. In case you want to know the detail of the picures, I suggest you take a look again on my previous post, shown by link above.

Summary of particle distribution due to photocatalysis

What is the different between DOC 3.1955 ppm and 6.15 ppm? Although I have briefly mentioned on previous post, I will explain again. The method to measure DOC for TiO2-UV batch there were 2. One, the sample with TiO2 particles in it, screened by 0.45 micro cellulose acetate (CA) membrane to remove TiO2. Second, I just measure samples like the way it is, with TiO2 in the samples. First result, DOC after 1 hour TiO2-UV batch, screened with 0.45 micro membrane to remove TiO2 particles, is 3.1955 ppm. Second result, DOC after 1 hour TiO2-UV batch, but this time inside the samples, contain TiO2 particles, obtained 6.15 ppm.

What does the picture tell us? In my opinion, although it is somehow still premature, but it still can be withdrawn basic perspectives. Based on blue one, which samples were screened first with 0.45 micro membrane to remove TiO2 particles, there seems increase of below 1 kD organic particles. Small fractions for 15-50 kD and above 50 kD. There were removal of organic carbon (DOC) of 15-50 kD and >50 kD. But this loss must be substracted with the increase of 1 kD particles. The total removal of DOC for 15-50 and 50 kD is (44%+28%)-(8%+7%) equals to 57% removal. But from this 57%, there was 3% converted to < 1 kD particles. Thus, total removal would be around 54% of photocatalysis. I am still talking about photocatalysis itself not yet combined with UF membrane.

Now, let us change to orange one, one with DOC based 6.15 ppm. The samples were not screened, just measured with a turbid solution like that. There was an increase for particles below 1 kD and above 50 kD. It's interesting. For particles below 1 kD, fraction amount of raw water is 27% while for TiO2-UV is 31%, increasing roughly 4%. For 15-50 kD, the fraction was the from 44% for raw water to 8%, but above 50 kD there was an increase from 28% to 42%.

Ok, now it’s for conclusion. I will make it per items:

1. Definitely there was an increase of particle size due to photocatalysis for particle size below 1 kD. The percentage was around 3-4%.

2. Less particle size between 15-50 kD ensued by photocatalysis, reaching around 36%.

3. Above 50 kD there are several conclusion, DOC particles for unscreened samples probably due to absorption 1-50 kD particles on the surface on TiO2 particles. This is confirmed by screened samples which had lower fraction amount (7%) compare to unscreened samples (42%).

4. From point 3 above, organic particles between 1-50 kD, were transferred due to photocatalysis around 3-4% to below 1 kD. 15-50 kD organic particles were removed 36%, and above 50 kD were removed 11%. The removal was due to absorption of organic particles of TiO2 particles as much as 35%.

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