Sample: Silica Gel 111, 115, 118.3, 119 were prepared by sol evaporation drying at 120 degree C. These sol are consisted by silica particle with different size, which are 10, 20, 50, 90 nm in diameter respectively.
The N2 adsorption/desorption isotherms following the type IV.
1. The interesting thing is the isotherms for gel 111 shows much higher than other samples.
2. The adsorption and desorption isotherms almost overlap each other in the initial part(0-0.6 p/p0) of isotherms(gel 111) , it looks more like Type II isotherm. And for other samples, there are no overlapping in the initial part of the adsorption and desorption isotherms, and the gap between two isotherms for gel 119 seems larger than 115 and 118.3, the difference among these three sample are particle size, and I have no idea how to link it with the above finds.
3.How to explain "the Adsorption cumulative volume of pores(BJH) are 1.864755, 0.411447, 0.447183, 0.446163 cm³/g corresponding for sample 111, 115, 118.3, 119 respectively.".
Hi Yang Liu_Lewis,
I don´t fully understand your question. Doy you mean what is the best way to explain your results or what are the reasons why you are obtaingin that results?
In the second case, I think the more pore volume and surface in 111 sample could be related to the intraparticle size. Perhaps an small particle size could form more porosity between particles.
Anyway, have you considered to repeat the analyse for 111sample?
Hi Daniel Martinez ,
Thanks for you suggestion. I am confusing that, unlike the sample 111(the isotherms are completely reversible), there is no overlap in the P/P0 range of 0 to 0.6 for the adsorption and desorption isotherms of sample 115, 118.3, 119. The partial enlarged image has been attached. The testing record shows the running time for sample 111 is 14 mins while the time for other three samples are 7 mins respectively.
BTW, those trapped nitrogen molecular should be able to escape from the meso-pores or macro-pores under such low pressure.