Review Reports

Round 1

Reviewer 1 Report

The authors investigate the Feasibility of nickel–aluminum complex hydroxides for recovering tungsten ions from aqueous media. Overall, the structure of this paper is well organized, and the presentation is clear. However, there are still some crucial problems that need to be carefully addressed before a possible publication. More specifically,

1. A motivation is not so clear to the reviewer. Please clarify the current difficulties in this topic and what kinds of remaining challenges are solved in this paper. What are the newly-added values in the community?
2. What is the difference between the proposed method and existing methods?
3. The reviewer is wondering whether this can be performed by using satellite or remote sensing images. Please add the discussion and analyze about feasibility by referring to the papers, g.,10.1109/TGRS.2020.3015157, 10.1109/TGRS.2021.3130716.
4. A future research direction should be pointed out in the conclusion.

Author Response

Please see the attachment.

Author Response File: Author Response.doc

Reviewer 2 Report

In this manuscript, authors report the adsorption and/or desorption capacity of tungsten ions using nickel–aluminum complex hydroxides. Meanwhile, the effect of temperature, contact time, pH, and coexistence on the adsorption of tungsten ions from aqueous media was demonstrated.  Generally, the manuscript is organized, and the results are meaningful.

1. In Fig.1, the standard XRD card of nickel hydroxide should be given. In addition, the XRD diffraction peaks of nickel hydroxide shift with the differention of molar ratios of Ni:Al. Why?
2. The nickel(Ni)-aluminum(Al) complex hydroxides show almost same morphological structure at various molar ratios. However, the amount of tungsten ions adsorbed using NA11 is the highest in all NA adsorbents. Please provide some reasonable explantion on this issue.
3. In Fig. 3, authors claimed that the quantity of adsorbed tungsten ions increases as the adsorption temperature increases when used NA11. What is the optimal adsorption temperature of adsorbed tungsten ions.
4. References 4 and 8 are duplicated. Please revise them.
5. The write-up should be further carefully checked through the whole text for some grammatical errors.
6. More recent work about application of metal hydroxides is suggested to be cited: Chin. Chem. Lett. 2022, 33, 890-892; Inorg. Chem. Front. 2021, 8, 3162-3166; Inorg. Chem. Front. 2021, 8, 3049-3054;  Inorg. Chem. 2021, 60, 12703-12708

Author Response

Please see the attachment.

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

The authors have well addressed the reviewer's concerns. No more comments.