A Robust Two-Step Process for the Efficient Conversion of Acidic Soybean Oil for Biodiesel Production

Round  1

Reviewer 1 Report

Very interesting study. Sound science and results mostly support conclusions. The only place that needs some improvement is the discussion of the effect of stirring speed. Plot is very difficult to distinguish and appears to indicate that the effect is very small and 700rpm optimal.

Figure 4 needs something to make symbols for curves more easily distinguished.

Figure 8 needs a legend. I know what the two curves should be but need a legend to see that they are.

Author Response

both Fig. 4 and Fig. 8 have been modified as requried.

Reviewer 2 Report

Authors present a comprehensive study on the conversion of acidic oil to biodiesel. They have tested different parameters, such as acid concentration, type of oil, recyclability of the acid, presence of a surfactant, etc. It shows a well-designed set of experiments and some interesting results in the field. Thus, I recommend its publication in Catalysts after considering some minor comments;

- Some of the effects studied do not show a clear trend. As an example, Figure 2 with the effect of the acid concentration or Figure 6 on the effect of the water/oil ratio. I recommend to check those data and try to elaborate a deeper explanation on what could be happening there, or just assume that there is not a trend with those parameters.

- I would advise to include in the abstract "soybean" when referring to the acidic oil.

-There are some typos, please check 

    Line 23 "it have" should be "it has".

    Line 77 researches should be research

Author Response

The related explanation/analysis has been included in the revised paper and highlighted in red color.

other english usage issue has been polished as suggested.