Hey there,

what do you mean by feed. The feed of solvent meaning supercritical fluid or the mass of the solid feed?

A question that comes to my mind is wether or not you should use the true value of the solute free feed-stock or the value that results from the actual experiment, when the extraction is done.

If nevertheless you like to use the true value you might be able to determine its value by a different extraction method such as Soxhlet extraction with an appropriate organic solvent.

Also I wonder, wether or not x0 and xk are actual parameters. It appears to me from your text above that they are state variables of the extraction model. But maybe I am wrong. Even though I know of Helena Sovovas models I am probably not as familiar with them as you are.

Best regards,

André

Hi, thanks for your input.

Now that you put it that way, I'm confused myself as well. I'm not sure whether the model is referred to solute-free  for mass of solid feed or the mass of solvent feed.

In my point of view, it will be nearly impossible to determine the exact solute-free mass of solid feed, and thus my question to the community. 

I have attached a snapshot of the paper and was wondering if you could clarify it for me if you are convenient. 

For your inquiry, I am planning to use the true value from my experimental works (optimized version). x0 and xk are just dimensionless fractions which are influence by the amount of solute extracted - since solute-free feed mass is constant.

I am new to the SFE study field and I'm trying to digest everything before running my experimentation and modelling.

Very much appreciated to you André !

Hi again,

I wonder wether or not you actually need the values initially, especially if you determine them by nonlinear parameter extimation anyways. The amount or fraction of solute extracted regardless of eassily accessible or not is found from your experimental results. Then this mass or fraction must be a weighted average of easily accessible and not easily accessible solute. This weighting fractor should be a model parameter that you will determine by parameter estimation. Do you agree?

Also, can you give me the title of the paper you used. The snapshot only holds part of the information and I'd like to read in in total to understand what is done there.

Regrads,

André

Hi André,

Thanks again for your time in replying my question.

To answer your question, yes - the overall extracted solute is the average of easily accessible and not easily accessible solute. However, the mass transfer model is divided into three parts (where all 3 are distinct from each other) - easily extracted part, not easily extracted part, and in-between part in simple terms.

Combining all this 3 parts will give the predicted extraction yield.

And here is the paper you requested.

http://www.sciencedirect.com/science/article/pii/S0896844696900558

It gave me a better explanation compared to other recent papers for me.

Regards,