Quantitative Study of the Enhanced Content and Chemical Stability of Functional Groups in Mesoporous Silica by In-Situ Co-condensation Synthesis

Round 1

Reviewer 1 Report

This paper reported the synthesis methods of two kinds amino-functionalized mesoporous silica (ami-g-MS and ami-MSN) via the direct grafting and in-situ co-condensation synthesis routes. The content and stability of amino groups in modified materials were measured, and their sorption  ability of some toxic metals in solution and the dynamic CO₂ adsorption capacity were reported.

This is an interesting work, the synthesis methods and some of the results will be interesting for the readers who are working in the fields of catalysis and environmenmatl science. I would like to recommend accepting it for publiction in the journal of CATALYSTS after minor modification.

1.      The method used for N content measurement was not clear, please provide the experimental details.

2.      Fig. 2,  The IR bands at 3436 and 1636 cm^-1 may also correspond to the surface -OH species and adsorpbed wáter on the solid. Discussion is required.

3.       In Table 2, C1, C2 , C3, R1, R2, and R3 defination should be provided.

4.       Manuscript contains some gramatical errors, for example, the errors in the following stences must be removed:

Page 2, Line 79: 4.0g of P123 was dissolved in 160ml of distilled water…..

(The PEO-PPO-PEO block copolymer is imposible to dissolve into water).

Page 3, Line 124: Compared with ami-g-MS, ami-MSN showed in Fig.1 (b) consisted of uniform nanospheres.

P5, L 163: This may because ami-g-MS was prepared via the direct grafting method, 

P5, L168-169: large amount of silanol groups (Si-OH) between oligomeric silica may lost,

P5, L172-173: ….resulting the load- ing of amino functional groups in ami-MSN would be more.    

|There are many other errors. Therefore, a complete revision of manuscript is required.

Author Response

Response to Reviewer 1 Comments

1. The method used for N content measurement was not clear, please provide the experimental details.

Response:

Thank you very much for your suggestion. Actually, the N content in the solution was measured by Total Nitrogen Analyzer (multi N/C 2100, Germany), we have added the content in the manuscript:

The stability of amino groups was analyzed by measuring the total nitrogen content in solution with a total nitrogen analyzer (multi N/C 2100, Germany). (Line 231 to 233)

 

2. Fig. 2, the IR bands at 3436 and 1636 cm-1 may also correspond to the surface -OH species and adsorpbed wáter on the solid. Discussion is required

Response：

Thank you for professional advice. Yes, through consulting a number of relevant literature, we found that the FT-IR adsorption peaks of N-H and -OH were partially overlapped and the influence of -OH could not be neglected. So we have added the relevant discussion as follows:

The broad band of medium intensity at 3436 cm-1 indicates the presence of primary aliphatic amines[26, 27], the adsorption band at 1636 cm-1 belongs to primary amines[28, 29]. However, the adsorption peaks at 3436 cm^-1 and 1636 cm^-1 could also be attributed to the stretching and flexural vibration of -OH in Si-OH and adsorbed water[30, 31]. Hence, the existence of nitrogenous functional groups was further confirmed combining by C, H, N elemental analysis. (Line 91 to 95)

Thank you again for your careful and professional suggestion.

 

3. In Table 2, C1, C2 , C3, R1, R2, and R3 defination should be provided。

Response：

Thank you for your suggestion. We have added their definition in detail, as follows:

C_p, C₁, C₂ and C₃ were the contents of each toxic metals (mg/L) in solution after pretreatment, MS adsorption, ami-g-MS adsorption and ami-MSN adsorption, respectively. R₁, R₂ and R₃ were the corresponding removal efficiencies of MS, ami-g-MS and ami-MSN, respectively ( R_x=100*(C_x/C_p) , x=1, 2, 3). (Line 183 to 185)

 

4. Manuscript contains some gramatical errors, for example, the errors in the following sentences must be removed:

• Page 2, Line 79: 4.0g of P123 was dissolved in 160ml of distilled water… (The PEO-PPO-PEO block copolymer is imposible to dissolve into water).
• Page 3, Line 124: Compared with ami-g-MS, ami-MSN showed in Fig.1 (b) consisted of uniform nanospheres.
• P5, L 163: This may because ami-g-MS was prepared via the direct grafting method, 
• P5, L168-169: large amount of silanol groups (Si-OH) between oligomeric silica may lost,
• P5, L172-173: …resulting the loading of amino functional groups in ami-MSN would be more. 

There are many other errors. Therefore, a complete revision of manuscript is required.

Response：

Thank you for your suggestion. We have made corresponding corrections:

(1)  160 mL of distilled water and 40mL of HCl (36wt%) were mixed and then 4.0g of P123 was dissolved in it, (Line 211 to 212).

(2)  Compared with ami-g-MS, ami-MSN showed in Fig.1 (b) were consisted of uniform nanospheres. (Line 78 to 79)

(3)  This may be attributed to that ami-g-MS was prepared by the direct grafting method, resulting the grafting efficiency was not high and the amino groups were more likely to distribute on the surface of the material. (Line 122 to 123)

(4)  the silanol groups (Si-OH) in oligomeric silica may lose a lot, while ami-MSN was extracted by extraction which retained more Si-OH groups. (Line 127 to 128)

(5)  …resulting that more amino functional groups could be loaded on ami-MSN. (Line 131)

And for the suggestion of a complete revision, we have found other errors through careful inspection, which have also been corrected in manuscript. Thank you again for your kind reminding.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript mainly compared two preparation methods of functionalized mesoporous silica and quantitatively studied the enhanced content and chemical stability of functional groups, which provided a reference for the preparation of adsorbents/catalysts with good properties. The manuscript is relatively well written and presents some interesting results. Minor revisions are needed before acceptance, there are several points to be considered:

1.      The conclusions in lines 127 to 128 do not match the topographic analysis results, please check it.

2.      The effective digits of data in Table 2 should be consistent.

3.      Correct the legend format of Figure 6.

4.      There are some typos, please check through the whole manuscript.

Author Response

Response to Reviewer 2 Comments

1. The conclusions in lines 127 to 128 do not match the topographic analysis results, please check it.

Response:

Thank you for your careful consideration. We have corrected it:

And the spherical structure could benefit the mass transfer performance, which may promote the sorption capacity of ami-MSN. (Line 82)

 

2. The effective digits of data in Table 2 should be consistent.

Response:

Thank you for your reminding. We have unified the data in Table 2, as follows:

		Pb	Cd	Ni	Cu	Zn	Mn
After pretreatment	Cp	5.60	4.10	12.20	8.90	5.60	1.70
MS	C1	4.10	2.80	9.10	7.90	5.20	1.10
	R1/%	26.80	31.70	25.40	11.20	21.20	35.30
ami-g-MS	C2	0.86	1.62	2.42	1.24	5.00	1.20
	R2/%	84.60	60.50	80.20	86.10	24.20	29.40
ami-MSN	C3	0.07	0.17	0.46	0.54	5.10	1.30
	R3/%	98.80	95.80	96.20	93.90	27.30	23.50

 

3. Correct the legend format of Figure 6.

Response:

Thank you for your suggestion, we have corrected the legend format of Figure 6.  However, because it is unable to paste the Figure 6 in the box, so we have uploaded the revised manuscript as attachment. Please see the attachment, thank you.

 

4.  There are some typos, please check through the whole manuscript.

Response:

Thank you for your suggestion, we have checked the manuscript and corrected the typos using “Track Changes”.

Author Response File: Author Response.pdf