Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work is aimed at investigating the possibility of the utilization of bottom ash from a thermal power plant as heterogeneous base catalysts for the production of biodiesel. The problem is very important and is related to improving the efficiency of the energy industry. It should be particularly noted that the authors used waste from real local productions, i.e. the work is not only academic in nature, but also focused on a specific production.

The manuscript is well written, the testing of the catalyst included reusability testing, which is important for practical application.

The comments relate essentially only to the design of figures. In Fig. 1, not only the results of fitting should be shown, but also the initial data, and in Fig. 2, 3 and 6, the lines for different samples should be shifted (the lines run into each other, and it is difficult to see the characteristic features).

I believe that the work can be published after minor revision.

Author Response

Dear reviewer, please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript entitled “Biodiesel production from waste frying oil (WFO) using a biomass ash-based catalyst” was well written by authors. The manuscript deals with waste valorisation is of interesting. Therefore, I recommend this article can be published after addressing the following comments.

1.     In Figure 2, the patterns must be separated with a space so that the readers can understand easily. Similarly, Figure.3 also.

2.     Hot filtration experiment has to be performed to confirm the leaching of the catalyst.

3.     XRD of spent catalyst needs to be performed to confirm whether C=O from unreacted oil or from the CaCO₃ formation.

4.     The authors reported a mixture of oils reported for transesterification in a particular ratio only. I suggest the authors perform different ratios of the mixture of oils also.

 

5.     After the end of the reaction also the acid value is high i.e., 1.23. Do the authors observe any soap formation during the reaction? If yes, mention the quantity.

Author Response

Dear reviewer, please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Now the manuscript can be published in its present form.