Experimental and Theoretical Investigation of Supercritical Processes: Kinetics of Phase Transitions in Binary “2-Propanol—CO₂” System

Round 1

Reviewer 1 Report

In the Manuscript, the kinetic mass transfer model for 2-propanol/CO₂ system is proposed based on experimental study of 2-propanol and near-critical CO₂ mixing kinetics. Original supercritical device setup is used for direct visual observation of 2-propanol/CO₂ phase boundary with and without presence of alginate wet-gel. The subject of research is of high interest in sol-gel science and supercritical drying, so the results and model approach are valuable in these fields. The whole study is covered with a wide literature background and has a fairly high scientific rigor (calculation errors, repeatability, and assumptions made). However, there are some minor questions, needed improvements, and undiscussed topic on research goal setting. Therefore, the current version of the Manuscript requires a Minor Revision.

1.    Even the Title proclaims the “investigation of supercritical processes”, which are of great practical importance. So, why does the Manuscript study the system in sub-supercritical conditions? To what extent the results of the study can be transferred to real supercritical processes?

2.   Please justify the use of alginate gels? What are the porosity and textural properties of used gels after supercritical drying? Do they have uniform pore shapes and size distributions? IMHO they can be very difficult to model diffusion through their pores. Why don't you use gels with more predictable and easier to model pore parameters (e.g. mesoporous silica impregnated with 2-propanol)?

3.  Please add errors estimation to Fig. 19. Also, correct "Koefficient" in the Y-axis label. Does the mass transfer coefficient change with T, P (given in terms of CO₂ density) for alginate gels or is it in scope of experimental error?

4.  Abstract section needs to be completely rewritten according to Journal’s Instruction for Authors: First sentence is redundant and tautological to the Title. Results and their quality are almost not stated.

5.  .Fig. 1 is untidy around 1.0 CO₂ mole fraction. Please, enhance the graph design (e.g. colors, markers, labels, Y-axis scale) to make it easier to read and better distinguish and convey the idea.

 

The quality of language is fine, I've only found some misspells.

Author Response

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Reviewer 2 Report

 

 Currently, supercritical technologies are a promising emerging field that finds its 29 application in a wide variety of industries

Figure 1…comes from ref 29, it has permisión?

Section 2.5

Equation 4-8 have many ítems not described..what is m?, A, B..and so on..it is obvious that V mis the molar volumen but not all readers are familiar with this

Is that AB in Figure 5…something to do with A and B in equation 5?, i think nothing ..but it is not clear

 

There some computer use in this manuscript, 3.2. Calculated curves of the phase transition kinetics present an algorithm, but in my opinion, after a mayor revisión this manuscript should transferred to a process eng. journal or something related to chemical engineering.

Author Response

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Reviewer 3 Report

Please refer to the review report attached.

Comments for author File: Comments.pdf

Please refer to the review report. 

Author Response

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Round 2

Reviewer 2 Report

accept as is