I have synthesized compound one without surfactant and other with some amount of surfactant.
From SEM micrograph particle size are smaller for one synthesized with surfactant but from BET analysis surface are for material synthesized without surfactant is slightly more than for the material synthesized by adding surfactant.
Ranjan Rai
Are your results representative of the whole sample? How much mass did you use for BET and what was the estimated mass you analyzed in SEM? How many particles did you analyze on SEM? Are you comparing the sizes based on the Sauter Mean Diameter, D[3,2]? The SEM produces a number mean, D[1,0] initially. How did you deal with aggregates and agglomerates in SEM?
Ranjan Rai
And there are a bunch of other questions to consider... And have you carried out an error budget?
Sir
Surface area I obtained for two samples are 7.78 m2/g and 8.2m2/g.
Error I have not considered.
Ranjan Rai
8 +/- 0.2 m2/g? That's only 2.5% when your material has a natural heterogeneity of around 5% (1 s.d.) depending on sampling. See:
Keys for Successful Analysis – Representative Sampling & Estimation of Standard Error Calculation
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190613KeysLD
Ranjan Rai
At unit density, the average particle size (Sauter Mean Diameter = 6/SSA) is ~ 0.75 microns or 750 nm. This is quite a fine powder.
there might be a tendency towards higher BET due to difference in porosity, distribution of aggregates and even size distribution, in particular very small particles possibly not detected by SEM. But your small differences in values do not suggest to argue too much on possible reasons.
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