Development of Pharmaceutical VOCs Elimination by Catalytic Processes in China

Round 1

Reviewer 1 Report

 

The authors have written a nice article about the elimination of VOCs by various processes such as condensation, adsorption, absorption, incineration, catalytic combustion, biodegradation, non-thermal plasma, photocatalytic combustion and electron beam. The authors also presented the various VOCs elimination techniques followed in China and other countries. It is clear that the adsorption is the popular method in China and followed by other techniques. The authors presented the advantages and disadvantages of all the processes. I would accept this paper after the following are being addressed.

 

1. The authors need to proofread the article very well to fix several English grammatical errors such as use of proper prepositions, singular vs plural and correct words and typos.
2. There is no Figure 18 as discussed on page 22. The authors mislabeled Figure 19 instead of Figure 18 based on the numbering scheme.

Author Response

Dear Editor-in Chief and reviewers:

Jun. 8^th, 2020

We submit our manuscript entitled “Development of pharmaceutical VOCs elimination by catalytic processes in China” to Catalysts for publication (catalysts-830386). You kindly gave us a chance to the major revision of this manuscript. Thank you for the comments of reviewers. The comments are very useful to improve our research. The reviewers’ comments pointed out some shortages in our work. We researched the comments carefully and revised our manuscript according to the comments. More details of changes can be found in the Responds to the Reviewers and revised manuscript. The revised places have been highlighted by green background.

 

Your sincerely

Jimmy Yun

 

 

 Reviewer 1

The authors have written a nice article about the elimination of VOCs by various processes such as condensation, adsorption, absorption, incineration, catalytic combustion, biodegradation, non-thermal plasma, photocatalytic combustion and electron beam. The authors also presented the various VOCs elimination techniques followed in China and other countries. It is clear that the adsorption is the popular method in China and followed by other techniques. The authors presented the advantages and disadvantages of all the processes. I would accept this paper after the following are being addressed.

1. The authors need to proofread the article very well to fix several English grammatical errors such as use of proper prepositions, singular vs plural and correct words and typos.

Responds: Thank you for your suggestion. We have done our best to improve the English writing of this article. The grammatical errors have been revised.

Line 15, 21, 27, 39 in page 1; line 45, 55-57, 59, 60, 61, 64, 72-74, 76, 81, 85, 86 in page 2; line 95, 98 in page 3; line 99, 107, 108, 115-117, 123, 124 in page 4; 130, 132, 135, 136, 139, 140, 142, 144, 148, 154 in page 5; line 162, 164, 165, 176 in page 6; line 184, 188, 196, 200 in page 7; line 205 in page 8; line 216-218, 233-235, 237, 247 in page 9; line 248, 249, 261, 274, 275 in page 10; line 284, 289, 300 in page 11; line 313, 317, 329 in page 12; line 341, 342, 353, 361, 368 in page 22; line 387-389, 403, 428, 429 in page 23; 440, 444, 449, 453, 455, 458, 460-464, 466, 467, 469, 475, 481 in page 25; line 490, 495, 502, 504, 506 in page 26; line 547, 553, 560 in page 28; line 576-578, 584, 593 in page 32; line 615, 616, 629 in page 34; line 653, 657, 685 in page 35; line 711, 723, 728 in page 39; line 744, 745, 752, 754, 755, 759, 760, 776 in page 40; line 795, 797-801, 807, 808, 811, 815-818 in page 42.

2. There is no Figure 18 as discussed on page 22. The authors mislabeled Figure 19 instead of Figure 18 based on the numbering scheme.

Responds: Thank you for your suggestion. We have mislabeled the Figure numbers after Figure 13 due to the several revision times of this manuscript. We have revised these Figure numbers of Figure 13-16. Figure 14 was revised to Figure 13. Figure 17 was revised to Figure 14. Figure 19 was revised to Figure 15.

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

In my opinion, your manuscript titled:  “Development of pharmaceutical VOCs elimination by catalytic processes in China” can be published in Catalysts after major revision. Please, you can find below my main remarks, suggestions and comments, and I would like to ask you for the kind responses of them.

You describe that: “Coagulation preparation involves the formation of larger particle agglomerates from fine particle suspensions. In the synthesis of pharmaceuticals, it is the process of mixing the active ingredients with helper constituents (often called coagulants) to produce a drug which is has the desired particle size. The physical nature of the coagulation process means that the waste produced via this method is primarily solid particles with little to no notable VOC production.” (verses 76-80)

Please, could you add the references which confirm these sentences?

In Tables 1 and 2, you present the extreme emission value of VOCs on the boundary of factories and The limiting value of specific pollutants in workshops and installations, respectively. Please, could you explain what does it mean “a” letter nest to several names of voltaic organic compounds and how you can explain the huge differences in the values for trichloroethylene or dichloromethane, and how are these parameters determined, for short time (e.g. 30 minutes) or one workday (e.g. 8 hours)?

You have to present the highest concentration of selected volatile organic compounds (VOCs) allowed in a short time (e.g. 30 minutes) for employees.

Please, could you show in Figure 1, the correlation between x kg of VOCs per 1 kg of drugs made in China and the year of production? The data presented in Figure 1 can suggest any changes in the elimination of VOCs during the production of medicaments in China in the period of ten years.

You write that: “Water and air are the most commonly used cooling mediums for the condensation process, but ice, cold salt solutions and organic mediums have been used where cooling temperatures of below 10℃ are required [4]. The condensation efficiency is sensitive to the temperature and pressure and is suitable for the removal of high concentration VOCs which exist liquefy at moderate temperatures [29-31]. (verses 129-133).

Please, could you describe what kind of the cooling mediums for the condensation process called as salt solutions and organic mediums has been used?

The data in Table 4 should be presented in the different form, in my opinion, you have to compare which catalysts are the best for the elimination of selected volatile organic compounds, e.g. toluene can be eliminated by the application of LaCoO₃, SrTi_1-XCu_XO₃, LaMnO₃/δ-MnO₂, MnO_x/K-Beta-SDS, Mn/R-SBA-15, CuO/ZnO nanocomposite, etc. The comparison of catalysts for each compound can be more clear and it can show for other researchers the best choice for their studies. You have to add also the information about the catalytic mechanism of VOCs elimination.  

In my opinion, each paragraph: “3.1.1. Noble metal catalysts”, “3.1.2. Non-noble metal catalysts”, “3.1.3. Perovskite catalysts“, “3.1.4. Concentrated oxidation catalysts” should be concluded by the tables with the information about the names of catalysts, their performance in the elimination of VOCs, the mechanism of the reaction, the achieved conversion of VOCs and the conditions of the catalytic process.

You have to add to the paragraph “3.1.1. Noble metal catalysts” the results obtained for bimetallic catalysts based on gold catalysts, e.g. Pt-Au, Cu-Au, Pd-Au, etc.

You have to develop the paragraph called “3.1.5. The influence factors on catalytic performance“, because you describe poorly only the presence of water and chloride in the catalytic activity.

 

You have to explain, why you used the reference [179] to describe the process in Figure 17. You write that: “V. Héquet et al. using a closed-loop reactor to study the mixture effect over P25 TiO₂/SiO₂ mixture (Figure 17) [179].” but this figure is assigned to [162] reference.

In the case of methods based on “Electron beam treatment”, the generation of active oxidizing radicals, e.g. ·OH and ·HO₂ can lead to the creation of toxic intermediates, especially in the case of the VOCs emission with unknown composition.  

Additional remarks

Please, could you improve the size of descriptions in Figures 3, 4, 6, 8, 16, 17  because the fonts are too small and presented form are hard to read?

You have to add in the text of manuscript references to the Figures 3-8, 14-19.

Please, could you add Figures 13, 14, 18?

You have to use the same style of description for all references.

English changes are required, especially in the final paragraph "4. Conclusions."

 

Kind regards,
Reviewer

Author Response

Dear Editor-in Chief and reviewers:

Jun. 8^th, 2020

We submit our manuscript entitled “Development of pharmaceutical VOCs elimination by catalytic processes in China” to Catalysts for publication (catalysts-830386). You kindly gave us a chance to the major revision of this manuscript. Thank you for the comments of reviewers. The comments are very useful to improve our research. The reviewers’ comments pointed out some shortages in our work. We researched the comments carefully and revised our manuscript according to the comments. More details of changes can be found in the Responds to the Reviewers and revised manuscript. The revised places have been highlighted by green background.

 

Your sincerely

Jimmy Yun

 

 

Reviewer 2

Dear Authors,

In my opinion, your manuscript titled: “Development of pharmaceutical VOCs elimination by catalytic processes in China” can be published in Catalysts after major revision. Please, you can find below my main remarks, suggestions and comments, and I would like to ask you for the kind responses of them.

1. You describe that: “Coagulation preparation involves the formation of larger particle agglomerates from fine particle suspensions. In the synthesis of pharmaceuticals, it is the process of mixing the active ingredients with helper constituents (often called coagulants) to produce a drug which is has the desired particle size. The physical nature of the coagulation process means that the waste produced via this method is primarily solid particles with little to no notable VOC production.” (verses 76-80)

Please, could you add the references which confirm these sentences?

Responds: Thank you for your suggestion. We have added the related references which can confirm these sentences.

Line 81 in page 2.

2. In Tables 1 and 2, you present the extreme emission value of VOCs on the boundary of factories and the limiting value of specific pollutants in workshops and installations, respectively. Please, could you explain what does it mean “a” letter nest to several names of voltaic organic compounds and how you can explain the huge differences in the values for trichloroethylene or dichloromethane, and how are these parameters determined, for short time (e.g. 30 minutes) or one workday (e.g. 8 hours)?

Responds: Thank you for your suggestion. The “a” letter nest to these name of VOCs means they will be put into effect after the publication of national standards.

The huge differences in the value for trichloroethylene or dichloromethane may be due to the different toxicity of these two compounds. The LD50 of dichloromethane is 1.25 g/Kg, while the LD50 of trichloroethylene is 2.40 g/Kg.

These parameters are determined by the following ways. These parameters are determined in 1 h by 3~4 simples for the average value. They are detected by the portable instruments or GC.

Line 85, 86 in page 2.

3. You have to present the highest concentration of selected volatile organic compounds (VOCs) allowed in a short time (e.g. 30 minutes) for employees.

Responds: Thank you for your suggestion. We have added the highest concentration of selected volatile organic compounds allowed in 1 h for employees in Table 1.

Line 89, 90 in page 2; Table 1.

4. Please, could you show in Figure 1, the correlation between x kg of VOCs per 1 kg of drugs made in China and the year of production? The data presented in Figure 1 can suggest any changes in the elimination of VOCs during the production of medicaments in China in the period of ten years.

Responds: Thank you for your suggestion. The correlation between x Kg of VOCs per Kg of drugs made in China the year of production has been added in Figure 1.

Figure 1. The production of bulk drugs and Chinese patent drugs and VOCs emissions from 2007 to 2016.

Line 109 in page 4.

5. You write that: “Water and air are the most commonly used cooling mediums for the condensation process, but ice, cold salt solutions and organic mediums have been used where cooling temperatures of below 10℃ are required [4]. The condensation efficiency is sensitive to the temperature and pressure and is suitable for the removal of high concentration VOCs which exist liquefy at moderate temperatures [29-31]. (verses 129-133).

Please, could you describe what kind of the cooling mediums for the condensation process called as salt solutions and organic mediums has been used?

Responds: Thank you for your suggestion. The cooling medium for the condensation process called as salt and organic mediums are mainly CaCl₂ solution, NaCl solution and ethylene glycol aqueous solution.

Line 135-136 in page 5.

6. The data in Table 4 should be presented in the different form, in my opinion, you have to compare which catalysts are the best for the elimination of selected volatile organic compounds, e.g. toluene can be eliminated by the application of LaCoO₃, SrTi_1-xCu_xO₃, LaMnO₃/δ-MnO₂, MnO_x/K-Beta-SDS, Mn/R-SBA-15, CuO/ZnO nanocomposite, etc. The comparison of catalysts for each compound can be more clear and it can show for other researchers the best choice for their studies. You have to add also the information about the catalytic mechanism of VOCs elimination.  

Responds: Thank you for your kindly suggestion. We have revised Table 4 in your suggested form. We have listed the selected VOCs as the first list and compared the catalytic performance of different catalysts for this VOCs elimination. The information about the catalytic mechanism of VOCs elimination has also been added in the last list.

Line 334 in page 13-21.

7. In my opinion, each paragraph: “3.1.1. Noble metal catalysts”, “3.1.2. Non-noble metal catalysts”, “3.1.3. Perovskite catalysts”, “3.1.4. Concentrated oxidation catalysts” should be concluded by the tables with the information about the names of catalysts, their performance in the elimination of VOCs, the mechanism of the reaction, the achieved conversion of VOCs and the conditions of the catalytic process.

Responds: Thank you for your suggestion. We have added tables the information about the names of catalysts, their performance in the elimination of VOCs, the mechanism of the reaction, the achieved conversion of VOCs and the conditions of the catalytic process in the paragraph “3.1.1. Noble metal catalysts”, “3.1.2. Non-noble metal catalysts”, “3.1.3. Perovskite catalysts”, “3.1.4. Concentrated oxidation catalysts”, “3.2 Photocatalytic oxidation” and “3.3 Non-thermal plasma process”.

Line 434, Table 5 in page 24; line 525, Table 6 in page 27; line 571, Table 7 in page 29, 30; line 601, Table 8 in page 33; line 704, Table 9 in page 37, 38; line 780, Table 10 in page 41.

8. You have to add to the paragraph “3.1.1. Noble metal catalysts” the results obtained for bimetallic catalysts based on gold catalysts, e.g. Pt-Au, Cu-Au, Pd-Au, etc.

Responds: Thank you for your suggestion. We have added the results obtained for bimetallic catalysts based on gold catalysts, e.g. Pt-Au, Cu-Au, Pd-Au, etc. in the paragraph “3.1.1. Noble metal catalysts”.

The single noble metal catalysts cannot satisfy the requirements of VOCs combustion. Therefore, some mixed noble metal catalysts have been developed to combine the advantages of different noble metal catalysts, such as Pt-Au, Cu-Au, Pd-Au. T. Tabakova et al. found that Pd deposition on the deposited gold showed the best catalytic performance for benzene combustion, which was totally eliminated at 200 ℃. It also showed good stability [78]. M. Hosseini et al. showed that the deposition of palladium on aurum supported on TiO₂ (Pd(shell) - Au(core)/TiO₂) can significantly improve the catalytic activity for oxidation of toluene and propylene [79]. Der Shing Lee et al. deposited Au-Pd bimetallic nanoparticles on CeO₂ for toluene degradation, which showed much better catalytic performance than Au/CeO₂ and Pd/CeO₂ catalysts due to the synergistic effect of gold and palladium [80]. The addition of non-noble metal also can improve the catalytic activity of noble metal catalysts. Roberto Fiorenza et al. prepared Au-Ag/CeO₂ and Au-Cu/CeO₂ bimetallic catalysts for alcohol oxidation and CO oxidation. These two catalysts shoed higher selectivity for intermediate products higher CO conversion at low temperature (100 ℃) than Au/CeO₂ [81]. The addition of Au also can improve the performance of Al₂O₃ supported Cu-Pt catalysts in DMDS oxidation [82].

Line 410-423 in page 23.

9. You have to develop the paragraph called “3.1.5. The influence factors on catalytic performance”, because you describe poorly only the presence of water and chloride in the catalytic activity.

 Responds: Thank you for your suggestion. The influence of surface area, crystal types, CO and life of catalysts have also been discussed.

Secondly, the surface area of catalysts is the main factors influence the catalytic activity. We’s research shows that MnO₂ with higher surface area showed much better catalytic performance than the one with lower surface area [98]. Thirdly, the crystal type of catalysts also influences the catalytic performance of the catalysts with the same content. For instance, catalytic performance of TiO₂ with different crystal type, namely rutile and anatase, showed different catalytic activity [74, 138].

CO is another poison for precious metal catalysts, so during the catalytic combustion, enough air is needed to avoid the generation of CO. The life of catalysts is also important for catalytic combustion. The main obstacle for the development of catalysts for the catalytic combustion of halogen and sulfur containing VOCs is the short life of common catalysts. Although V oxides shows less catalytic efficiency than other catalysts, it still used in the elimination of halogen and sulfur containing VOCs due to its long catalytic life [122]. Because after the installation of catalytic combustion equipment, it will be in operation for a long time, so the life of catalysts determines the cost of catalytic combustion.

Line 607-612, 620-627 in page 34.

10. You have to explain, why you used the reference [179] to describe the process in Figure 17. You write that: “V. Héquet et al. using a closed-loop reactor to study the mixture effect over P25 TiO₂/SiO₂ mixture (Figure 17) [179].” but this figure is assigned to [162] reference.

Responds: The reference of this Figure is wrong. The correct one is [162] reference, which has been revised to Figure 14 and reference 167.

Line 695 in page 36.

11. In the case of methods based on “Electron beam treatment”, the generation of active oxidizing radicals, e.g. ·OH and ·HO₂ can lead to the creation of toxic intermediates, especially in the case of the VOCs emission with unknown composition.  

Responds: Thank you for your suggestion. We have added this point in this section.

Line 798-800 in page 42.

Additional remarks

12. Please, could you improve the size of descriptions in Figures 3, 4, 6, 8, 16, 17 because the fonts are too small and presented form are hard to read?.

Responds: Thank you for your kindly suggestion. We have improved the size of descriptions in Figures 3, 4, 6, 8, 16, 17 to make sure the fonts can be clearly read. Figure 16 and 17 has been revised to Figure 14 and 15.

Figure 3. A typical activated carbon VOC removal (solvent recovery) plant [26].

Figure 4. Schemes of thermal oxidation. (a) Regenerative thermal oxidation; (b) recuperative thermal oxidation [26].

Figure 6. Schematic diagram of a reverse flow reactor [26].

Figure 8. The ratios of VOCs elimination technologies used in China (a) and other countries (b) (the numbers in the brackets are the numbers of companies using the related technologies) [52].

Figure 14. 420-L continuous closed-loop photocatalytic reactor: 1) photocatalytic unit containing the TiO2 photocatalytic medium and the UV lamps, 2) fan, 3) air input and sampling points for analysis, 4) air tranquilization chamber, 5) flow rate measurement. [167]

Figure 15. The schematic diagram of the VUV-PCO system [186].

Line 157 and 166 in page 6; line 192 in page 7; line 213 in page 9; line 692, 696 in page 36.

13. You have to add in the text of manuscript references to the Figures 3-8, 14-19.

Responds: Thank you for your suggestion. We have added these Figures as references in the text of manuscript.

Line 148 in page 5; line 159 and 171 in page 6; line 194 in page 7; line 226 in page 9; line 576 in page 31; line 663 and 669 in page 36.

14. Please, could you add Figures 13, 14, 18?

Responds: Thank you for your suggestion. These Figures have been removed due to the reason that they were unnecessary for this article. However, we have forgot to revise the Figure numbers. We have revised the Figure numbers. Figure 14 was revised to Figure 13. Figure 17 was revised to Figure 14. Figure 19 was revised to Figure 15.

15. You have to use the same style of description for all references.

Responds: Thank you for your suggestion. We have revised the references with improper style.

Line 824-829 in page 42; 830-840, 842-844, 848-866, 868-887 in page 43; line 888-890, 892-896, 898-920, 924-944 in page 44; 945-1001 in page 45; 1002-1058 in page 46; 1060-1117 in page 47; line 1118, 1119, 1121, 1123-1128, 1130-1174 in page 48; line 1175-1191, 1193-1231 in page 49; 1232-1289 in page 50; 1290-1336 in page 51.

16. English changes are required, especially in the final paragraph "4. Conclusions."

 Responds: Thank you for your suggestion. We have done our best to improve the English writing of this manuscript to make sure it can show the original meaning of authors. The places revised have been highlighted in the manuscript by green background as following.

Line 15, 21, 27, 39 in page 1; line 45, 55-57, 59, 60, 61, 64, 72-74, 76, 81, 85, 86 in page 2; line 95, 98 in page 3; line 99, 107, 108, 115-117, 123, 124 in page 4; 130, 132, 135, 136, 139, 140, 142, 144, 148, 154 in page 5; line 162, 164, 165, 176 in page 6; line 184, 188, 196, 200 in page 7; line 205 in page 8; line 216-218, 233-235, 237, 247 in page 9; line 248, 249, 261, 274, 275 in page 10; line 284, 289, 300 in page 11; line 313, 317, 329 in page 12; line 341, 342, 353, 361, 368 in page 22; line 387-389, 403, 428, 429 in page 23; 440, 444, 449, 453, 455, 458, 460-464, 466, 467, 469, 475, 481 in page 25; line 490, 495, 502, 504, 506 in page 26; line 547, 553, 560 in page 28; line 576-578, 584, 593 in page 32; line 615, 616, 629 in page 34; line 653, 657, 685 in page 35; line 711, 723, 728 in page 39; line 744, 745, 752, 754, 755, 759, 760, 776 in page 40; line 795, 797-801, 807, 808, 811, 815-818 in page 42.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Dear Authors,

In my opinion, your corrected manuscript titled: "Development of pharmaceutical VOCs elimination by catalytic processes in China" can be published in Catalysts in present form.

Kind regards,
Reviewer