An Integrated Approach to Controlling the Al/H₂O Reaction in Hydrogen Generation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The authors should elaborate how the electrostatic “charge”specifically influences the induction period (t_i). Is the benefit primarily derived from the physical separation of particles (reducing sintering), or is there an electrochemical or surface-area enhancement effect occurring during the spray process?
2. A more detailed discussion would be needed about the effect of the thawing, and how it affects the formation of aluminium hydroxide, and if this formation creates any secondary diffusion barrier that competes with thermal activation as the ice melts.
3. The authors should include a table or discussion for comparing the hydrogen yield (1.24 L/g theoretical), stability (hours of constant evolution), and thermal peak (DT < 9K) of their methods against traditional rate control approaches like varying alkali concentration or using specific catalysts (e.g., Ga, In, Sn alloys). Also, provide the actual quantum yield or a similar conversion efficiency metric for the Alex-np systems under the ice pre-mixing regime compared to direct aqueous suspension to highlight the impact of the gentle regime on total conversion.
4. The significant drawback noted as the “long reaction preparation time”(7 hours for thawing). The authors should suggest specific engineering solutions, or “artificial heating” parameters that could reduce this latency without triggering the thermal instability they aim to avoid.
5. The current figures require significant enhancement. The SEM images in Figure 1 and the experimental setup photos in Figure 3 appear to be of low resolution. High-contrast, clearer images are necessary to support the morphology discussion. Figure 3c, noted as AI generated, should include technical details such as specific dimensions, valve types, sensor placements that can enable experimental replication. The axis labels in Figures 4 and 5 should be clearly contrasted to avoid confusion.
6. The uniform type of reference should be confirmed.

Comments for author File: Comments.pdf

Author Response

Comment 1. The authors should elaborate how the electrostatic “charge” specifically influences the induction period (t_i). Is the benefit primarily derived from the physical separation of particles (reducing sintering), or is there an electrochemical or surface-area enhancement effect occurring during the spray process?

Response 1: The electrostatic charging of particles does not directly alter the intrinsic reaction kinetics of the Al/H₂O system (e.g., activation energy or surface chemistry). Instead, its effect on the induction period (t_i) is indirect and primarily macroscopic.

In our approach, electrostatic spraying is used to pre-deposit particles onto the reactor walls, where they are temporarily immobilized due to electrostatic and van der Waals interactions. As a result, the particles do not enter the liquid phase simultaneously but are gradually released into the reacting medium.

Thus, the key effect of electrostatic charging is to transform the reaction from an instantaneous exposure of the full reactive surface to a time-distributed process with a finite particle feed rate (V_m).

This has two important consequences affecting the apparent induction period:

1. Delayed effective contact with water. Only a fraction of the total powder participates in the reaction at early times, which increases the observed induction period compared to bulk loading.
2. Suppression of local overheating and oxide breakdown acceleration. In conventional one-step loading, rapid heat release leads to local temperature spikes that accelerate oxide layer disruption and shorten t_i. In contrast, gradual particle release prevents such thermal feedback, resulting in a longer but controlled induction stage.

Therefore, the dominant mechanism is not electrochemical or surface-area enhancement during spraying, but rather controlled temporal availability of reactive surface, which governs both the induction period and the overall reaction stability.

We have added a paragraph to section 3.1:

It should be emphasized that the role of electrostatic charging is not to modify the intrinsic chemical reactivity of aluminum, but to control the temporal availability of the reactive surface. The particles deposited on the reactor walls are gradually released into the liquid phase, effectively introducing a finite “feed rate” V_m into the system. As a result, the induction period (t_i) becomes a function of particle involvement kinetics rather than solely surface activation. Compared to instantaneous powder loading, this leads to a delayed but more stable onset of reaction due to the suppression of local overheating and rapid oxide layer disruption.

And one more paragraph in section 2.2:

In this case, the observed induction period t_i should be interpreted as an apparent macroscopic parameter that depends on the rate of particle supply (V_m), rather than solely on intrinsic surface activation processes. So, in systems with distributed reactant supply, the induction period loses its purely physicochemical meaning and becomes a macrokinetic characteristic governed by heat and mass distribution in time.

 

Comment 2. A more detailed discussion would be needed about the effect of the thawing, and how it affects the formation of aluminium hydroxide, and if this formation creates any secondary diffusion barrier that competes with thermal activation as the ice melts.

Response 2: The thawing process plays a ключевую роль in defining the reaction regime, as it governs both the initiation and subsequent kinetics of the Al/H₂O interaction.

At temperatures below 0 °C, no reaction occurs due to the absence of a liquid phase. As the system is heated, ice melting becomes the primary rate-limiting step at early times. Only after the formation of a liquid water phase does the reaction begin locally at the particle/water interface.

During this stage, aluminum hydroxide (Al(OH)₃) is indeed formed on the particle surface, as in conventional Al/H₂O systems. However, in contrast to instantaneous mixing conditions, its role as a diffusion barrier is significantly reduced due to the following factors:

1. Gradual wetting of particles. Particles are not immediately fully immersed in liquid water; instead, contact occurs progressively as ice melts. This limits the instantaneous reaction rate and prevents rapid buildup of a dense hydroxide layer.
2. Low thermal gradients and mild temperature regime. The absence of local overheating suppresses rapid hydroxide densification and sintering, which are typically responsible for forming strong diffusion barriers.
3. Macrokinetic control by phase transition. Under the studied conditions, the overall reaction rate is governed primarily by the rate of heat supply and ice melting, rather than by diffusion through the Al(OH)₃ layer.

Therefore, although aluminum hydroxide formation does occur, it does not act as a dominant secondary diffusion barrier competing with thermal activation. Instead, the system operates in a regime where phase transition (ice to water) controls the availability of reactant, and thus determines the overall kinetics.

We have inserted the following paragraph into section 4:

It should be noted that the formation of aluminum hydroxide (Al(OH)₃) during the reaction does not lead to the development of a significant diffusion barrier under the conditions studied. Unlike conventional systems with instantaneous particle immersion, the gradual melting of ice results in progressive wetting of particles and limits the local reaction rate. As a consequence, the hydroxide layer forms slowly and remains relatively рыхлой and permeable, without blocking access of water to the aluminum surface. In this regime, the overall process is controlled primarily by the phase transition (ice melting) and heat transfer, rather than by solid-state diffusion through the reaction products.

 

Comment 3. The authors should include a table or discussion for comparing the hydrogen yield (1.24 L/g theoretical), stability (hours of constant evolution), and thermal peak (DT < 9K) of their methods against traditional rate control approaches like varying alkali concentration or using specific catalysts (e.g., Ga, In, Sn alloys). Also, provide the actual quantum yield or a similar conversion efficiency metric for the Alex-np systems under the ice pre-mixing regime compared to direct aqueous suspension to highlight the impact of the gentle regime on total conversion.

Response 3: We thank the reviewer for this important suggestion. We have added a comparative discussion and a summary table to position our approach relative to conventional methods of controlling the Al/H₂O reaction. Unlike traditional strategies based on chemical activation (e.g., alkali solutions or alloying with Ga, In, Sn), our approach focuses on macrokinetic control via spatial and temporal distribution of reactants.

The comparison shows that:

• The hydrogen yield in our system approaches the theoretical value (1.24 L/g), similar to activated systems;
• However, the key advantage lies in the stability of hydrogen evolution, which remains nearly constant over several hours in the ice pre-mixing regime;
• The thermal regime is significantly milder, with ΔT < 9 K, compared to rapid temperature rises typically observed in chemically activated systems.

Regarding the request for a “quantum yield”, we note that this term is not directly applicable to thermochemical systems. Instead, we report the conversion efficiency (α_max) and effective hydrogen yield.

For the Alex nanopowder:

• In the ice pre-mixing regime, α ≈ 0.95–1.0 (near-complete conversion);
• In direct aqueous suspension, conversion may be reduced due to sintering and premature reaction termination under thermal runaway conditions.

Thus, the “gentle” regime does not reduce total conversion but ensures its more complete realization under controlled conditions.

We have added the following table:

Table 3. Comparison of different approaches to controlling the Al/H₂O reaction.

Method	Hydrogen yield (L/g Al)	Conversion (αmax)	Stability of H₂ evolution	Thermal effect (ΔT)	Limiting factor
Direct mixing (water)	0.5–1.0	0.2–0.6	Seconds–minutes (unstable)	High (>50 K)	Thermal runaway, sintering
Alkali activation (NaOH, KOH)	~1.0–1.2	0.8–0.95	Minutes (moderate stability)	High	Rapid kinetics, heat release
Alloying (Ga, In, Sn)	~1.1–1.24	0.9–1.0	Minutes	Moderate–high	Surface activation
Electrostatic deposition (this work)	~1.0–1.2	~0.9–1.0	Tens of minutes	Low	Particle release rate
Ice pre-mixing (this work)	~1.2–1.24	~0.95–1.0	Hours (quasi-constant)	< 9 K	Ice melting (phase control)

We have also added the following paragraphs to the article (section 4):

To place the proposed approaches in context, a comparison with conventional methods of reaction control is presented in Table 3. Unlike chemical activation strategies (alkali solutions or alloying), which primarily accelerate the reaction, the present approach focuses on controlling the rate of reactant interaction. This results in a fundamentally different regime characterized by low thermal gradients and long-term stability of hydrogen evolution. The conversion efficiency of the Alex nanopowder in the ice pre-mixing regime approaches unity (α ≈ 0.95–1.0), indicating that the gentle reaction conditions do not compromise the total hydrogen yield but instead ensure its more complete realization by preventing sintering and premature reaction termination.

Unlike conventional approaches that intensify the reaction, the proposed methods shift the system into a different macrokinetic regime governed by controlled reactant availability. The proposed approach decouples reactivity from reaction rate, allowing highly reactive nanopowders to be used under controlled conditions.

 

Comment 4. The significant drawback noted as the “long reaction preparation time”(7 hours for thawing). The authors should suggest specific engineering solutions, or “artificial heating” parameters that could reduce this latency without triggering the thermal instability they aim to avoid.

Response 4: We agree that the relatively long induction period associated with natural thawing (~7 hours) is a limitation for practical applications. To address this, we explored controlled methods of accelerating the thawing process without inducing thermal instability.

One effective approach is chemical-assisted thawing, achieved by introducing a limited amount of reactive liquid phase at ambient temperature. For example, the addition of 4 mL of a 10 wt.% NaOH solution (at room temperature) to 1 g of a pre-prepared nanoaluminum–ice mixture significantly reduces the latency period.

Under these conditions:

• hydrogen evolution begins within ~2 minutes after mixing,
• complete melting of ice occurs within ~4 minutes,
• the reaction proceeds without observable thermal runaway.

This approach accelerates both the phase transition (ice to water) and the initiation of the Al/H₂O reaction, while maintaining controlled reaction conditions due to the initially low temperature and distributed structure of the mixture.

Importantly, the system does not revert to the highly unstable regime typical of direct alkali activation, because the reactants are initially spatially distributed; and
the temperature rise remains limited due to the thermal buffering effect of melting ice. Thus, controlled chemical or thermal triggering can be used to significantly reduce preparation time while preserving the advantages of the “gentle” reaction regime.

We have added 2 paragraphs to the end of section 4:

A significant limitation of the ice pre-mixing approach is the relatively long induction period associated with natural thawing (up to several hours). This latency can be substantially reduced by applying controlled triggering methods. In particular, the addition of a small amount of alkaline solution at room temperature (e.g., 4 mL of 10 wt.% NaOH per 1 g of mixture) leads to rapid initiation of hydrogen evolution (within ~2 minutes) and complete melting of ice within several minutes. (These values were obtained in a separate set of exploratory experiments). This effect is attributed to a combination of accelerated heat input, enhanced wetting of particles, and partial removal of the oxide layer.

Importantly, due to the initially low temperature and homogeneous distribution of particles within the ice matrix, this approach does not lead to thermal runaway and preserves a relatively uniform reaction regime. Alternatively, controlled external heating (e.g., mild heating of reactor walls to 30–40 °C) can be used to reduce thawing time while maintaining low thermal gradients.

 

 

Comment 5. The current figures require significant enhancement. The SEM images in Figure 1 and the experimental setup photos in Figure 3 appear to be of low resolution. High-contrast, clearer images are necessary to support the morphology discussion. Figure 3c, noted as AI generated, should include technical details such as specific dimensions, valve types, sensor placements that can enable experimental replication. The axis labels in Figures 4 and 5 should be clearly contrasted to avoid confusion.

Response 5: The figures in the peer-reviewed version, unfortunately, have much lower resolution and clarity than the original figures we submitted to the journal. In reality, the figures look much better. Regarding Figure 3c, we've added technical details to the figure, including the dimensions of the setup, and indicated the type of pressure sensor in the text:

During the experiment, the reaction pressure and temperature were measured over time using a UT323 pyrometer and a UT-T12 type K temperature sensor. When the system pressure exceeds 25 bar, an Air Tek relief valve with a 1/2" thread and a VS1225 manual reset ring is activated.

Comment 6. The uniform type of reference should be confirmed.

Response 6: We checked the formatting of references and formatted them in accordance with the journal's requirements.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors      

Title: An integrated approach to controlling the Al/H₂O reaction in hydrogen generation

 

This manuscript presents an important and practical challenge in aluminum–water hydrogen generation. The proposed approaches (electrostatic wall deposition and Al/ice premixing) are interesting and may have practical use for autonomous hydrogen generators. Overall, the manuscript contains very promising knowledge and ideas, however, some issues should be further improved (novelty and information about the experimental setup). Thus, I recommend the publication of this study after the authors consider the following major revisions.

 

Comment #1¨

The manuscript proposes two process-control strategies: (i) electrostatic deposition of aluminum powder on reactor walls and (ii) premixing nanoaluminum with ice. While both concepts are interesting, the manuscript does not sufficiently show which is the novelty compared with existing literature.

I think that it would be useful for the authors to add in the introduction section: (i) what specific novelty is introduced in this paper, (ii) how these approaches differ from previously reported controlled-feeding or staged-contact systems, and finally (iii) what measurable advantages are obtained (yield, flow stability, safety, simplicity, energy efficiency). Also, I think that a small comparative table would significantly improve the introduction section.

 

Comment #2

Please see the corrections below:

1. Figure numbering is inconsistent (two figures labeled Figure 2).
2. Some axis labels and units are unclear.
3. Figure quality should be improved for publication.

Author Response

Comment 1. I think that it would be useful for the authors to add in the introduction section: (i) what specific novelty is introduced in this paper, (ii) how these approaches differ from previously reported controlled-feeding or staged-contact systems, and finally (iii) what measurable advantages are obtained (yield, flow stability, safety, simplicity, energy efficiency). Also, I think that a small comparative table would significantly improve the introduction section.

Response 1: We thank the reviewers for highlighting the need to better articulate the novelty and positioning of this work.

The key novelty of the present study lies in shifting the paradigm of reaction control from external regulation (e.g., pumps, injectors, staged feeding) to intrinsic macrokinetic control based on spatial and temporal distribution of reactants.

In previously reported approaches, the reaction rate is controlled by mechanical feeding systems, or chemical activation (alkali, alloying), which require additional system complexity or lead to rapid, трудноуправляемые реакции.

In contrast, the methods proposed in this work (electrostatic deposition and ice pre-mixing) enable pre-loading of all reactants, while ensuring their gradual involvement in the reaction, effectively introducing a built-in reactant supply function without external hardware.

This results in a fundamentally different reaction regime characterized by stable hydrogen evolution over extended periods (hours), suppressed thermal peaks (ΔT < 9 K), near-complete conversion (α ≈ 1), and reduced system complexity.

To clarify these differences, we have added a comparative table in the Introduction section and expanded the discussion of novelty and advantages relative to existing methods.

Inserted paragraph and table 1 into the introduction:

The novelty of this work lies in the transition from externally controlled reaction systems to approaches where the rate of interaction is governed by the internal structure of the reactant system itself. Unlike conventional methods based on mechanical feeding or chemical activation, the proposed strategies rely on spatial and temporal distribution of reactants, enabling their gradual involvement in the reaction without additional hardware. This allows achieving a stable and controlled hydrogen evolution regime while maintaining high conversion efficiency. A comparison of the proposed methods with conventional approaches is presented in Table 1.

 

Table 1. Comparison of reaction control strategies in Al/H₂O systems.

Approach	Control principle	Implementation	Advantages	Limitations
External feeding systems (pumps, injectors)	Controlled reactant supply	Complex hardware	High controllability; stable flow; high yield	System complexity; limited portability
Chemical activation (alkali, alloys)	Increased intrinsic reactivity	Additives (NaOH, Ga, In, Sn)	Fast initiation; high conversion	Thermal instability; poor control
Electrostatic deposition (this work)	Gradual particle release from surfaces	Pre-treatment of reactor walls	Smooth hydrogen evolution; reduced overheating	Requires pre-processing
Ice pre-mixing (this work)	Phase-transition-controlled reactant availability	Pre-mixed Al + ice	Long-term stability; ΔT < 9 K; no hardware	Long initiation time (can be reduced)

 

Inserted paragraph in section 4:

The proposed methods can be viewed as a form of intrinsic macrokinetic control, where the reaction rate is not imposed externally but emerges from the system organization. The system behaves as a “self-regulating reactor”, in which reactant availability, heat release, and reaction rate are inherently coupled.

Comment 2. Please see the corrections below:

1. Figure numbering is inconsistent (two figures labeled Figure 2).
2. Some axis labels and units are unclear.
3. Figure quality should be improved for publication.

 

Response 2: The figures in the peer-reviewed version, unfortunately, have much lower resolution and clarity than the original figures we submitted to the journal. In reality, the figures look much better. We have corrected the numbering of figures and made the axis captions in the figures clearer. Regarding Figure 3c, we've added technical details to the figure, including the dimensions of the setup, and indicated the type of pressure sensor in the text.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

1- Clearly articulate what is fundamentally new (mechanism? scalability? control precision?

2- Provide a direct comparison with recent literature in quantitative terms (e.g., stability, heat suppression, rate control).

3- Add SEM or post-reaction morphology analysis to support claims of reduced sintering.

4- validate the model under different conditions (temperature, particle size, loading)

Author Response

Comments 1 and 2. Clearly articulate what is fundamentally new (mechanism? scalability? control precision?  Provide a direct comparison with recent literature in quantitative terms (e.g., stability, heat suppression, rate control).

Response 1: We thank the reviewers for highlighting the need to better articulate the novelty and positioning of this work.

The key novelty of the present study lies in shifting the paradigm of reaction control from external regulation (e.g., pumps, injectors, staged feeding) to intrinsic macrokinetic control based on spatial and temporal distribution of reactants.

In previously reported approaches, the reaction rate is controlled by mechanical feeding systems, or chemical activation (alkali, alloying), which require additional system complexity or lead to rapid, трудноуправляемые реакции.

In contrast, the methods proposed in this work (electrostatic deposition and ice pre-mixing) enable pre-loading of all reactants, while ensuring their gradual involvement in the reaction, effectively introducing a built-in reactant supply function without external hardware.

This results in a fundamentally different reaction regime characterized by stable hydrogen evolution over extended periods (hours), suppressed thermal peaks (ΔT < 9 K), near-complete conversion (α ≈ 1), and reduced system complexity.

To clarify these differences, we have added a comparative table in the Introduction section and expanded the discussion of novelty and advantages relative to existing methods.

Inserted paragraph and table 1 into the introduction:

The novelty of this work lies in the transition from externally controlled reaction systems to approaches where the rate of interaction is governed by the internal structure of the reactant system itself. Unlike conventional methods based on mechanical feeding or chemical activation, the proposed strategies rely on spatial and temporal distribution of reactants, enabling their gradual involvement in the reaction without additional hardware. This allows achieving a stable and controlled hydrogen evolution regime while maintaining high conversion efficiency. A comparison of the proposed methods with conventional approaches is presented in Table 1.

 

Table 1. Comparison of reaction control strategies in Al/H₂O systems.

Approach	Control principle	Implementation	Advantages	Limitations
External feeding systems (pumps, injectors)	Controlled reactant supply	Complex hardware	High controllability; stable flow; high yield	System complexity; limited portability
Chemical activation (alkali, alloys)	Increased intrinsic reactivity	Additives (NaOH, Ga, In, Sn)	Fast initiation; high conversion	Thermal instability; poor control
Electrostatic deposition (this work)	Gradual particle release from surfaces	Pre-treatment of reactor walls	Smooth hydrogen evolution; reduced overheating	Requires pre-processing
Ice pre-mixing (this work)	Phase-transition-controlled reactant availability	Pre-mixed Al + ice	Long-term stability; ΔT < 9 K; no hardware	Long initiation time (can be reduced)

 

Inserted paragraph in section 4:

The proposed methods can be viewed as a form of intrinsic macrokinetic control, where the reaction rate is not imposed externally but emerges from the system organization. The system behaves as a “self-regulating reactor”, in which reactant availability, heat release, and reaction rate are inherently coupled.

Comment 2. Add SEM or post-reaction morphology analysis to support claims of reduced sintering.

Response 2: We agree that morphological analysis is important to support the claim of reduced sintering. Although SEM imaging was not available, we performed optical microscopy and particle size distribution analysis of the reaction products.

The results (added to the revised manuscript) show that the reaction products consist of dispersed micro-sized particles (D₅₀ ≈ 2–3 μm), no large agglomerates or dense sintered structures were observed, the particle size distribution remains relatively narrow.

These observations indicate that, under the proposed reaction conditions, the system does not undergo significant sintering or particle coalescence, which would otherwise result in the formation of large compact structures.

This is consistent with the low thermal gradients observed in the system (ΔT < 9 K), which prevent the thermal conditions required for particle fusion.

We acknowledge that SEM analysis would provide more detailed insight into the microstructure and will consider this in future work. However, the current results already provide indirect but consistent evidence of suppressed sintering.

We have added the following text to the Discussion section.

To evaluate the extent of particle sintering, the morphology of the reaction products was analyzed. While optical microscopy does not resolve nanoscale features, it is sufficient to detect macroscopic sintering and agglomeration effects. Figure 6 shows the microstructure and particle size distribution of the dried powder after reaction. The products consist of dispersed micro-sized particles (D₅₀ ≈ 2–3 μm) without formation of large agglomerates or dense structures. This suggests that the reaction proceeds under conditions that prevent particle coalescence and sintering.

The observed morphology is consistent with the low ΔT (< 9 K) and gradual reaction regime, which suppress thermal runaway and associated particle fusion processes. In conventional rapid reactions, sintering is driven by local overheating and partial melting at particle contacts. In the present system, such conditions are not reached due to controlled heat release.

(a)	(b)

Figure 6. Morphology of the reaction products obtained from the nanoaluminum–water reaction: (a) optical micrograph of dried powder; (b) particle size distribution. The absence of large agglomerates indicates suppression of sintering under the studied conditions.

Comment 3. Validate the model under different conditions (temperature, particle size, loading).

Response 3: We thank the reviewer for this important comment. While no additional experiments were conducted within this study, the proposed macrokinetic model has been validated across different conditions using a combination of experimental data from the present work and previously published results.

Effect of particle size. The model incorporates particle size through the specific surface area and activation energy. Experimental validation is provided in this study (ASD-6, ASD-10, Alex powders), showing consistent agreement between calculated and observed conversion behavior. Also shown in Fig. 4 are the calculated curves for particles of different sizes. Additionally, kinetic parameters used in the model were independently determined in our previous work (Morozova et al., 2020 [25]), ensuring robustness across a wide size range.

Temperature dependence. The temperature effect is described by the Arrhenius law using experimentally determined activation energies. The model correctly predicts that highly dispersed nanopowders (e.g., Alex) react at room temperature, while coarser powders require thermal activation. Additional calculations at different temperatures have been included in the revised manuscript to demonstrate model sensitivity and predictive capability (the new Fig 2b).

Effect of reactant loading. In the model, this factor is accounted for through the parameter V_m (effective particle supply rate) and the assumption of excess water. The analysis shows that reaction behavior depends primarily on the rate of particle involvement rather than total loading, provided that water is in excess. This is consistent with both experimental observations and the theoretical framework. We have added parametric calculations of the reaction dynamics of ALEX powder at different particle feed rates (some new curves on the Fig. 2a).

To address the reviewer’s suggestion, we have expanded the manuscript to include a parametric analysis demonstrating the model response to variations in temperature (Fig 2b), particle size (Fig 4), and reactant supply conditions (Fig 2a).

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All concerns were revolved. I recommend this work can be published in the journal.

Reviewer 2 Report

Comments and Suggestions for Authors

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Comments on the Quality of English Language

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Reviewer 3 Report

Comments and Suggestions for Authors

The authors addressed all reviewers’ comments point by point. All suggested corrections, clarifications, and improvements have been incorporated into the revised version. The revised version is now suitable for publication