Biochar from Microwave Pyrolysis of Artemisia Slengensis: Characterization and Methylene Blue Adsorption Capacity

Round  1

Reviewer 1 Report

The manuscript entitled " The Biochar Yield and Adsorbability from Microwave Pyrolysis of Artemisia Selengensis" describes the preparation of biochar from Artemisia Selengensis and its characterization after the optimization of the experimental procedure in terms of temperature, heating rate and the use of additive . Several manuscripts have been published about this topic and the authors must better described the novelty of their work  The study is at the same time smart and after an extensive revision could be accepted for publication.

I suggest to modify the Title in: Biochar from microwave pyrolysis of Artemisia Selengensis: characterization and methylene blue adsorption capacity.

Introduction section: describe the main methods to prepare activated charcoal. I suggest to add these couple of references about this topic (  Anal. Methods, 2015, 7, 4811-4815 and J. Env. Manag. 2007, 85, 833-846).

Section 2.1: Add an image about Artemisia Selengensis used in this study.

Add geographic coordinates for Beguazhou.

Change table 1 in Table 1.

Describe why have you mentioned rice straws. Comparison?

“Also according to Luo and Wang’s researches, the main product of cellulose pyrolysis is volatile, this makes biochar produced by pyrolysis selengensis have more potential with more pore. [14,15] Furthermore, artemisia selengensis straws have little ash, which means there are little no-organic impurities in the biochar, which is a great condition for producing good adsorptive biochar”. These sentences are speculations. Add experimental results or remove them.

2.3.2 100 ml of HCl solution at pH=1? In which solvent/solution the mixture was boiled?

2.3.3 Rephrase the entire section because it is unclear.

3.1-3.2-3.3-3.4 remove single factor analysis. It could be used for example “The effect of ….”

Conclusion: Rephrase this paragraph: “The biochar yield reached a peak when the heating rate is 1℃/s, and the adsorbability of biochar 247 reached a peak when the heating rate is 1.5℃/s. The biochar yields and adsorbability are respectively 248 similar when the heating rate is in other value.”

Author Response

Dear reviewer:

  Thank you for your hard work and useful advise. 

Point 1: I suggest to modify the Title in: Biochar from microwave pyrolysis of Artemisia Selengensis: characterization and methylene blue adsorption capacity.

Introduction section: describe the main methods to prepare activated charcoal. I suggest to add these couple of references about this topic (Anal. Methods, 2015, 7, 4811-4815 and J. Env. Manag. 2007, 85, 833-846).

Section 2.1: Add an image about Artemisia Selengensis used in this study.

Add geographic coordinates for Beguazhou.

Change table 1 in Table 1.

Response 1: We’ve modified the title and introduction section, added the image of artemisia selengensis used in this study, and added the geographic coordinates of Baguazhou.

Point 2: Describe why have you mentioned rice straws. Comparison?

Response 2: In the paper, we compared the composition of artemisia selengensis and rice straw, this is because our research were based on rice straw, artemisia selegensis is the first time for us to pyrolysis. And after compared the composition of artemisia selegensis and rice straw, we found the artemisia selegensis contents more cellulose, thus it is difficult to mush and reuse. This also indicated that traditional pyrolysis is not suitable for artemisia selegensis.

Point 3: “Also according to Luo and Wang’s researches, the main product of cellulose pyrolysis is volatile, this makes biochar produced by pyrolysis selengensis have more potential with more pore. [14,15] Furthermore, artemisia selengensis straws have little ash, which means there are little no-organic impurities in the biochar, which is a great condition for producing good adsorptive biochar”. These sentences are speculations. Add experimental results or remove them

Response 3: In section 2.1, we mentioned Luo and Wang’s researches because we want to prove the biochar produced by AS has porous properties. Thank you for your advise, we’ve modified this sentence.

Point 4: 2.3.2 100 ml of HCl solution at pH=1? In which solvent/solution the mixture was boiled?

Response 4: In section 2.3.2, pH=1 means the concentration of HCl solution is 0.1 mol/L. The mixture is biochar and HCl solution.

Point 5: 2.3.3 Rephrase the entire section because it is unclear.

3.1-3.2-3.3-3.4 remove single factor analysis. It could be used for example “The effect of ….”

Conclusion: Rephrase this paragraph: “The biochar yield reached a peak when the heating rate is 1℃/s, and the adsorbability of biochar 247 reached a peak when the heating rate is 1.5℃/s. The biochar yields and adsorbability are respectively 248 similar when the heating rate is in other value.”

Response 5: The title of 3.1-3.4 have been modified, 2.3.3 and conclusion are also modified.

Reviewer 2 Report

The paper describes the preparation of char from spent Artemisia selengensis. The paper might be published but after adjustment of English. Authors do not proprely use some terms, for example: microporous instead of micropores or decreasing instead of decrease or increasing instead of increase (quite massively in lines 122-137). Summing up, please read the text carefully.

The major question considering this work is of economical character. Spent artemisia contains high level of water (close to 95%). Thus, the amount of char (independent on the methodology used) is significanly small. Therefore, some calculation of  process costs with relation to other means of utilization of this waste (for example - composting) should be done.

Other small issues are as follows:

Authors do not use metal chlorides and metal carbonates as additives - they simply use zinc chloride and sodium dicarbonate - generalization is not justified;

Artemisie selengensis is a Latin name of the plant and should be written as Artemisia selengensis;

remove word researchers in line 60.

Author Response

Dear reviewer:

    Thank you for your useful advise. We’ve modified some sentences in section 3.

Point 1: The major question considering this work is of economical character. Spent artemisia contains high level of water (close to 95%). Thus, the amount of char (independent on the methodology used) is significanly small. Therefore, some calculation of  process costs with relation to other means of utilization of this waste (for example - composting) should be done.

Response 1: You mentioned the economical character in this work because of the high moisture content. It’s a very brilliant question. For now, because of the low efficiency of magnetron, microwave pyrolysis have no significant advantages. And you also mentioned composting, this technology is now available, but there are still about 40% AS need to be reused. So we want use microwave pyrolysis to produce high value productions. At first, hydrogen-rich gas is the target product because of its high moisture content. However, the result was not OK, but the adsorption capacity of biochar was very good. And according to the result, this method has potential on producing active carbon. 

Round  2

Reviewer 1 Report

The manuscript can be accepted in its present form. Check title "methylene and not methylence" and references style. 

Author Response

Dear reviewer:

    Thank you for your recognition of our work. The spelling mistake has been corrected. And the  references style has also been improved according to the journal requirements.

Best regards!