Preparation and Characterization of Acid-Activated Bentonite with Binary Acid Solution and Its Use in Decreasing Electrical Conductivity of Tap Water
, Chalermpong Saenjum 2,3, Takehiro Nakamura 1 and Naohito Kawasaki 1,4,*
Round 1
Reviewer 1 Report
After reading the manuscript, I make some observations. 1. Why are the concentrations of 5 mol/L? Wasn't the bentonite dissolution expected? 2. The increase in the conductivity of the solution was not expected since the dissolution of bentonite leads to a higher concentration of ions in solution. 3. What is the relationship between the dissolution of bentonite and the increase in surface area? 4. Have conductivity measurements been carried out on the solid or on the solution? 5. What is the relationship between the decrease in conductivity and technological application of bentonite? 6. Page 2, line 86-91: Why use solutions of various cations and anions when no results from the adsorption experiment were presented? 7. How did the authors determine the composition of bentonite, since there is a great variety of bentonites in the literature? 8. The presence of Si atoms was not observed in the spectra shown in Fig. 3? 9. Is the bentonite used in the experiments natural? The submitted manuscript needs major revisions before being accepted for publication.Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Review of manuscript
minerals-1314464
Finding new materials and ways to purify water and other natural environment is an important challenge today, so the manuscript presented is very relevant.
While reading the manuscript several questions arose and some points require clarification.
1.It is not clear from the manuscript why binary acid systems were chosen to modify bentonite.
For what purpose was the relatively weak phosphoric acid used?
Why do binary acid solutions reduce CEC to a greater extent than Singl-acid solutions?
Why did the phosphate anion, which is a strong complexing agent, have no practical effect on the Al release into the solution?
- Why do the peak positions on the XRD patterns shift toward the soap angle after being treated with acids? Doesn't the conversion of bentonite to the H-form lead to a decrease in the interplanar distance of montmorillonite?
- On lines #206-207, the authors write that: "However, the sodium ion concentration increased with increasing treatment time…. ". This does not follow from Figure 6. Clarification is needed.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I congratulate the authors for their comments, and for reviewing the manuscript.
I recommend the publication of the revised version of the manuscript.
