Kinetics, Isotherms and Adsorption–Desorption Behavior of Phosphorus from Aqueous Solution Using Zirconium–Iron and Iron Modified Biosolid Biochars
, Dane Lamb 2,4,*, Anitha Kunhikrishnan 1,2 and Mohammad Mahmudur Rahman 1Round 1
Reviewer 1 Report
The authors in this work evaluated
Kinetics, isotherms and adsorption-desorption behavior of phosphorus from aqueous solution using zirconium iron and iron modified biosolid biochars. The manuscript is well written. The paper can be considered for publication in this journal provided that the authors can further address the following issues.
- I think the metals are expensive and they exhibit toxicity at low concentration, in this case how it would be feasible to use metal-based materials for the adsorption of excess P ?
- Surprisingly, the surface area of biochar is lesser than the metal incorporated biochar? The reason behind this should be discussed clearly.
- I suggest providing relevant microscopy images corresponding to mapping images/spectra to show the proof of the material composition.
- The recyclability of powder-based materials is extremely difficult. The amount of recovered materials following each cycle should be given and discussed.
- I suggest seeing this literature. Journal of Environmental Chemical Engineering
Volume 9, Issue 4, August 2021, 105688
Author Response
Reviewer# 1 Comments and our response
The manuscript is well written. The paper can be considered for publication in this journal provided that the authors can further address the following issues.
Comment 1: I think the metals are expensive and they exhibit toxicity at low concentration, in this case how it would be feasible to use metal-based materials for the adsorption of excess P ?
Response: We thank to the reviewer for the excellent comments and recommended for the publication of our manuscript. We have incorporated all suggestions recommended by the reviewer and revised the manuscript accordingly. We believe that the reviewer’s comments have significantly enhanced this manuscript.
Contamination of trace elements may threaten the environment as well as human health. The remediation process of contaminated water is expensive. Hence, innovative, cost effective, multifunctional and stable materials (adsorbents) needs to be developed for the removal of pollutants in wastewater. Biochar is promising and due to its binding capacity, this has strong affinity to bind trace elements. Modified biochars are more effective in removing pollutants than pristine biochar due to its surface functional properties and higher adsorption capacity. Generally, Fe, Mn, Ni, Cu, Zr, Cs and Zn metals are used for the modification of biochars. A study compared the costs of modified biochars (Cs-biochar, Zn-biochar, Zr-biochar and biochars) for the treatment of vanadium in contaminated water and reported that Zr-biochar ($104/t) is somewhat expensive compared to Cs-biochar ($57/t) and Zn-biochar ($87/t) whereas biochar itself is quite expensive ($274/t) as the efficiency is much lower than modified biochars. We agree with the reviewer that metals are expensive, however, comparing with different metals cost along with removal efficacy of contaminants we think, metals modified biochar’s are cost effective considering the actual remediation cost (Meng et al., 2018).
Literature showed that metals/metals oxides modified materials are very promising to clean up pollutants from wastewater/aqueous solution. Many studies have investigated the modified materials including activated carbon, modified clay, modified biochars, nanomaterials etc used for remediation of pollutants such as As, Cr, Sb, P, V, Cd, Ni, Pb etc in wastewater and found that the leaching of metals from modified materials is minimal and biocompatibility tests showed no toxicity (Deb et al., 2021; Rahman et al., 2021a; Deb et al., 2022).
We have included these in the revised manuscript (lines 77-81 and lines 443-448).
Comment 2: Surprisingly, the surface area of biochar is lesser than the metal incorporated biochar? The reason behind this should be discussed clearly.
Response: We have included the explanation in the revised manuscript why the surface area of biochar is less. For reviewer convince, please see below:
BET analysis demonstrated that both the specific sure face area (SSA) and pore volume of metal incorporated biochar are much higher than pristine biochar (Table 1). The reason is due to the loading with the Zr or Fe particles; and combination with Zr and Fe particles on the biochar surface. Thus, loading with metal (single or dual) on biochar surface greatly affected the structure of the pore size to be opened on the surface of the Zr, Fe or Zr-Fe modified biochar (Kizito et al., 2015). Therefore, the SSA of BC, Zr-BC, Zr-FeBC and Fe-BC was 4.64, 75.85, 25.51 and 24.02 m2 g-1, which increases with smaller particle size (Kizito et al., 2015) and the average particle size was determined to 1292, 79, 235 and 249 nm, for BC, Zr-BC, Zr-FeBC and Fe-BC, respectively (Table 1). Additionally, SSA positively correlated with an increased pore volume of biochar (Xu et al., 2021).
Comment 3: I suggest providing relevant microscopy images corresponding to mapping images/spectra to show the proof of the material composition.
Response: The materials composition was determined using SEM-EDS and TEM-EDS analysis, which is included in our previous publications (Rahman et al., 2021b). However, we have included SEM images, SEM-EDS and TEM elemental mapping in the SI section. Please see Figure S1-S3 in the SI section.
Comment 4: The recyclability of powder-based materials is extremely difficult. The amount of recovered materials following each cycle should be given and discussed.
Response: We acknowledge the reviewer comment. Thus, we have added the amount of recovered materials following each cycle in the revised manuscript (please see lines 436-438).
Comment 5: I suggest seeing this literature. Journal of Environmental Chemical Engineering
Volume 9, Issue 4, August 2021, 105688
Response: We have cited the article as suggested by the reviewer in the revised manuscript.
Reviewer 2 Report
This manuscript by Rahman et al. aims to assess the sorption of phosphorus onto modified biochars. This work is very classical in its shape, using batch conditions, far from field conditions, and testing some variables as pH, temperature, competition, etc. This work is not at all as it looks like hundreds of manuscript already published on the same topic, and what's more disturbing is the fact that the authors already published exactly the same papers (extensively cited in their manuscript even unpublished as Rahman et al. 2021b) with the same setup using other ions. It's true that there is still several ions to test in the periodic table.
I cannot concur with the publication of a copy/past (even large section of text) of other manuscripts, just changing an ion by another. Therefore, i recommend to reject this manuscript.
Author Response
Reviewer# 2 Comments and our response
Comment: This manuscript by Rahman et al. aims to assess the sorption of phosphorus onto modified biochars. This work is very classical in its shape, using batch conditions, far from field conditions, and testing some variables as pH, temperature, competition, etc. This work is not at all as it looks like hundreds of manuscript already published on the same topic, and what's more disturbing is the fact that the authors already published exactly the same papers (extensively cited in their manuscript even unpublished as Rahman et al. 2021b) with the same setup using other ions. It's true that there is still several ions to test in the periodic table. I cannot concur with the publication of a copy/past (even large section of text) of other manuscripts, just changing an ion by another. Therefore, i recommend to reject this manuscript.
Response: We sincerely thank the reviewer for the valuable comment. At present, there is a considerable demand for a multifunctional, innovative, cost-effective, stable, and ecofriendly material for the remediation of various pollutants from the environment including wastewater as untreated water can be toxic for the aquatic environment and biota when disposed to the surface water. By achieving these and to prove the effectiveness of our newly developed modified biochar materials, we utilised them for the adsorption of multiple pollutants such as As, Sb, and P. This clearly indicates that establishment of metals modified biochar materials and there is a great value to communicate research underpinned by excellence with new means of applications. Finally, we have checked the text by plagiarism software to avoid any duplication with our previous publication. We agree that the experimental set up including adsorption parameters, characterizations and research designs are similar with our previous publications. However, these similar experimental designs are well expected in the specific literature, which is evident in many publications already published. Please see an example in literature:
Zhang et al. (2013) and Zhang et al. (2014) synthesized zirconium-chitosan composite which was applied to remove multi contaminant such as Cr(VI) and Vanadium (V). Similarly, Zhang and Gao (2013) synthesized biochar based AlOOH composite material which was also utilized for simultaneous removal of arsenic, methylene blue and phosphate.
We have also updated the cited article Rahman et al. 2021b in the revised manuscript.
Reviewer 3 Report
Manuscript Number: water-1458781
Title: Kinetics, isotherms and adsorption-desorption behavior of phosphorus from aqueous solution using zirconium-iron and iron modified biosolid biochars
Article Type: Article
In the manuscript an experimental research concerning adsorption of phosphorus using different types of biochars is presented. A detailed analysis of physicochemical properties of biochars were performed. Four different mathematical models of adsorption kinetics were evaluated. Next, the impact of process conditions like biochar concentration and presence of other substances onto the adsorption efficiency were examined. According to the Web of Science database Authors have experience in this field of science. This work is a continuation of their previous research. They refer to appropriate papers in the text.
The manuscript is well written although some sentences should be corrected/enhanced. The data presentation and discussion of the results is escellent. Below I am presenting my remarks:
- The English of the manuscript and overall text editing should be enhanced. For example:
Line 37: “waste water” but in line 44: “wastewater”
Line 41: “Cheese factors”
Line 219: “when pH values decreased from 5 to 11”
Line 236: “Thus, the point of zero charge (pHPZC) was found to be 5.7” this is isoelectric point
line 289: “the calculated regression coefficients (R2 )” it is coefficient of determination
line 317: “3.1.4. Effect of biochar density and ionic strength” I think that it should be biochar concentration?
line 326: “A decreasing trend of P removal efficiency may be associated with the unsaturated of active sites” - Table 1: Could Authors give the standard deviations of values given in the table? What kind of average size is used for particle characterization. How was the size of particles determined?
- Impact of biochar concentration. Could authors discuss this issue more precisely? Why does there exist an optimum biochar concentration? The mechanism of this phenomenon should be explained.
- Figure 5A: since the data points represents different processes one should not introduce the trend line to graph. I suggest to use a bar graph in this case.
- Figure 5B: The temperature unit is capital “K”.
- The quality of the figures should be enhanced (the markings “A” “B” “C” etc.)
Author Response
Reviewer# 3 Comments and our response
Comment: In the manuscript an experimental research concerning adsorption of phosphorus using different types of biochars is presented. A detailed analysis of physicochemical properties of biochars were performed. Four different mathematical models of adsorption kinetics were evaluated. Next, the impact of process conditions like biochar concentration and presence of other substances onto the adsorption efficiency were examined. According to the Web of Science database Authors have experience in this field of science. This work is a continuation of their previous research. They refer to appropriate papers in the text. The manuscript is well written although some sentences should be corrected/enhanced. The data presentation and discussion of the results is excellent. Below I am presenting my remarks:
Response: We thank reviewer for the positive comments on our manuscript. We have considered the reviewer’s queries and suggestions and revised the manuscript accordingly.
Comment 1: The English of the manuscript and overall text editing should be enhanced. For example:
Line 37: “waste water” but in line 44: “wastewater”
Line 41: “Cheese factors”
Line 219: “when pH values decreased from 5 to 11”
Line 236: “Thus, the point of zero charge (pHPZC) was found to be 5.7” this is isoelectric point
line 289: “the calculated regression coefficients (R2 )” it is coefficient of determination
line 317: “3.1.4. Effect of biochar density and ionic strength” I think that it should be biochar concentration?
line 326: “A decreasing trend of P removal efficiency may be associated with the unsaturated of active sites”
Response: We have edited the English of the manuscript thoroughly by a native speaker and revised the text as per reviewer queries above.
Comment 2: Table 1: Could Authors give the standard deviations of values given in the table? What kind of average size is used for particle characterization. How was the size of particles determined?
Response: We have included the standard deviation in the Table 1. The average particle size was used of the average of three measurement of each sample. The details determination of particle size is included in supporting information (SI). Please see section S2 in SI section.
Comment 3: Impact of biochar concentration. Could authors discuss this issue more precisely? Why does there exist an optimum biochar concentration? The mechanism of this phenomenon should be explained.
Response: We have included the more discussion and the mechanisms is explained in the revised manuscript (please see lines 352 to 363).
Comment 4: Figure 5A: since the data points represents different processes one should not introduce the trend line to graph. I suggest to use a bar graph in this case.
Response: We have provided the bar graph in Figure 5A in the revised manuscript as suggested by reviewer.
Comment 5: Figure 5B: The temperature unit is capital “K”.
Response: Corrected.
Comment 6: The quality of the figures should be enhanced (the markings “A” “B” “C” etc.)
Response: The quality of the figures is improved in the revised manuscript as per reviewer’s suggestion.
Reviewer 4 Report
In my opinion, this paper is "average" but I do not have any critical comments. I recommend publishing it in present form.
Author Response
We appreciate reviewers' positive feedback on our manuscript.
