Differential pore volume distribution means pore size distribution, or porosity spectrum, as you prefer. This means: which pore volume can be ascribed to which pore size. This is of huge importance for characterising any porous material, as the total porosity itself doesn't say anything about the pore size(s), nor an average pore size doesn't say anything about the representativity of such a size. Only thye pore-size distribution brings such complete information.
Alain
The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, earth sciences, soil mechanics and engineering.
Some of the pores are so small, that the pore volume aailable to different molecules will depend on their size. Therefor the concept of porasity is some what orbitratory but is best taken to be that determined by helium displacement in active carbons. The macroporous may be observed with with an oridinary microscope and their volume can be determined with directly with a mercury porosimeter,
Ref:Porous Media Fluid Transport and Pore Structure
By F Dullien'
books.google.co.in/books?isbn=0323151353
The different presentations of pore size distribution dervied from the gas absorption method and the mercury porosity are connected with some problems, This concerns especially the use of logarithemically differential pore volume distribuition
ink.springer.com/article/10.1007%2Fs002160051166
The pore volume distribution over pore diameter is expressed in terms of the distribution function Fv
Fv = - (dV / d log D)
where V is pore volume. The function is such that area under the function in any pore diameter range yields volume of pores in that range.
how can we decide the of which pore volume sample should be passed in porous media
Both [dV vs. D]& [dV/d(LnD) Vs. D] are the pore volume distribution plots . Both dV and dV/d(LnD) have the units of pore volume (cc or cc/g) . One has to be careful. While [dV vs, D] is the actual pore volume distribution plot, [dV/d(LnD) vs. D] is the plot of the mathematical slope of the cumulative pore volume V in the natural log scale vs. the pore diameter D. While the former plot may look uncouth , untidy, dishevelled, disorderd, the latter looks like a smooth, well dressed person. Moreover (but not always) the peaks of the two plots might be at two entirely different pore diameters ! I always go by [ dV vs. D] because that IS the real thing inside your sample . You may climb the wrong tree by relying on [dV/d(LnD) Vs. D] just because it is well dressed !! Check out an example .Attached.
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