Next Article in Journal
Study on the Risk Zone of Hydrogen Leak Diffusion in High-Pressure Hydrogen Transmission Pipeline Station Fields
Previous Article in Journal
NRBO-XGBoost-Optimized High-Fidelity Temperature Correction for UAV-Based TIR Imagery and Its Application for Monitoring Coal Fire
Previous Article in Special Issue
Impact of Thermo-Oxidative Aging on Flame Retardancy of Melamine Formaldehyde Particle Boards: Processes and Performance Degradation Analysis
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Fire
Volume 8
Issue 12
10.3390/fire8120463
fire-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Optimizing Xanthan Gum for Enhanced Fire Extinguishing Performance of Eco-Friendly Short-Chain Fluorocarbon Surfactant Foam

by
Wenjun Zhao
1,
Zhisheng Xu
1 and
Long Yan
1,2,*
1
Institute of Disaster Prevention Science and Safety Technology, School of Civil Engineering, Central South University, Changsha 410075, China
2
State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China
*
Author to whom correspondence should be addressed.
Fire 2025, 8(12), 463; https://doi.org/10.3390/fire8120463 (registering DOI)
Submission received: 10 November 2025 / Revised: 20 November 2025 / Accepted: 24 November 2025 / Published: 28 November 2025
(This article belongs to the Special Issue Fire Prevention and Flame Retardant Materials—2nd Edition)
Browse Figures
Versions Notes

Abstract

Addressing the environmental challenges posed by traditional foam extinguishing agents containing persistent pollutants, the development of eco-friendly alternatives has become imperative. This study investigates the effect of xanthan gum (XG) on the fire extinguishing performance of PFH-BZ foam formulated with short-chain fluorocarbon surfactant. By analyzing foam formation, drainage characteristics, and suppression process, the underlying mechanism by which XG influences foam extinguishing performance was elucidated. The results indicate that XG exerts dual effects on foam properties. While its viscosity-increasing effect improves foam stability, excessive XG addition impairs foaming and spreading capabilities, reducing fuel surface coverage and smothering efficiency. Moreover, a high concentration of XG hinders drainage behavior, which in turn inhibits the formation of spreadable aqueous films, thereby reducing cooling and extinguishing efficiency. The PFH-BZ foam with 0.02 wt.% XG exhibits excellent foaming and spreading capabilities, enabling rapid coverage of fuel surfaces. Additionally, its moderate drainage characteristics facilitate spreadable aqueous film formation, achieving efficient cooling and smothering effects. The optimized PFH-BZ foam exhibits the shortest extinction time of 35.4 s, the lowest transient temperature rise of 60.8 °C, and the highest cooling rate of 16.8 °C/s. Environmental assessments reveal that the optimized PFH-BZ foam exhibits higher biodegradability than conventional foam.

Graphical Abstract

1. Introduction

Petrochemical fires, typical hydrocarbon liquid fires, pose distinct hazards including large-scale combustion areas, high explosion potential, rapid flame propagation, generation of highly toxic combustion byproducts, significant firefighting complexities, and great secondary disaster risks [1,2,3,4]. Traditional extinguishing agents, such as water and dry powder, offer limited efficacy against such complex fires, potentially exacerbating fire development due to inadequate cooling capacity or potential fueling effects [5,6]. Foam fire extinguishing agents, particularly aqueous film-forming foam (AFFF), have emerged as highly effective for liquid fuel fires [7,8,9]. This excellent extinguishing efficacy is attributed to the superior cooling, smothering, and isolating effects of foam blankets and aqueous films [10,11]. However, traditional AFFF contains long-chain perfluoroalkyl and polyfluoroalkyl substances (PFAS), such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) [12,13,14]. These substances pose significant ecological and health risks due to their environmental persistence, mobility, bioaccumulation, and potential toxicity [15,16,17,18]. Consequently, there is an urgent need to develop advanced foam fire extinguishing agents that combine high fire extinguishing performance with environmental friendliness [19,20,21,22].
Short-chain fluorocarbon surfactants exhibit reduced ecological impact and considerable recyclability, along with excellent amphiphobicity [23,24]. These properties position them as promising alternatives to long-chain fluorocarbon surfactants in AFFFs [25,26]. In our previous work, a betaine-type zwitterionic short-chain fluorocarbon surfactant (PFH-BZ) was synthesized and exhibited excellent surface activity and foam performance. The results indicated that PFH-BZ exhibited a critical micelle concentration (cmc) of 1.05 mmol/L, with corresponding surface tension, foaming height, and foam stability values of 18.5 mN/m, 30.8 cm, and 70.8%, respectively [27]. Notably, when compounded with N,N-dimethyldodecan-N-amine oxide (OB-2) at an optimal 1:2 molar ratio, the surfactant system achieved a significantly reduced cmc of 0.14 mmol/L, greatly reducing the required fluorocarbon surfactant concentration while maintaining considerable surface activity, foaming capacity, and foam stability. These findings establish a key foundation for developing eco-friendly fluorocarbon foam extinguishing agents that exhibit excellent spreading performance and the ability to generate sufficient and stable foams [22].
Foam stabilizers, as another key functional component in firefighting foams, play a vital role in maintaining foam stability, enhancing fire extinguishing efficacy, and preventing reignition [28,29]. Previous studies investigated the influence of three types of foam stabilizers (inorganic salts, long-chain alcohols, and polymers) on the physicochemical properties of PFH-BZ/OB-2 foam solution, including interfacial activity, rheological behavior, foam performance, and drainage characteristics, and proposed corresponding mechanisms [27,30,31]. Among these stabilizers, xanthan gum (XG) exhibited outstanding stabilizing effects, attributable to its double-helical macromolecular structure and abundant hydrophilic groups [31,32]. These structural features allow XG to greatly increase solution viscosity while minimally impacting surface activity [33,34,35]. Consequently, XG effectively inhibits foam destabilization behaviors, including gravitational drainage, coarsening, and coalescence [36,37,38]. By constructing three-dimensional hydrogen-bonded network structure, XG effectively enhanced foam stability and water retention, contributing to fire control and suppression through oxygen isolation, thermal cooling, and chemical inhibition [39]. Similar stabilizing effects were validated in aerogel foams and silicone-based foams [40,41]. Moreover, XG can form a protective film at the foam-ethanol interface due to its pronounced thixotropy characteristics [42,43]. This film significantly enhanced foam spreadability on polar fuel surfaces, thereby improving alcohol resistance and extinguishing efficacy against polar fuel fires. Despite these advancements, existing studies primarily focus on macroscopic assessments of fire extinguishing performance through extinction and burnback times. However, the specific mechanism by which XG enhances foam suppression remains poorly understood, especially within short-chain fluorocarbon foam systems.
In this study, the influence of XG on the foaming capability, drainage characteristics, and fire extinguishing performance of short-chain fluorocarbon surfactant-based foam was investigated. The study aims to elucidate the underlying mechanism of XG and determine its optimal concentration for firefighting applications. Moreover, biodegradability assessments were conducted to evaluate the environmental compatibility of the short-chain fluorocarbon surfactant-based foam. The findings provide critical theoretical insights and experimental evidence for the development and performance enhancement of eco-friendly foam fire extinguishing agents.

2. Materials and Methods

2.1. Materials

The synthetic route of zwitterionic short-chain fluorocarbon surfactant (PFH-BZ) was proposed in our previous work [27]. N,N-dimethyldodecan-N-amine oxide (OB-2, 30%) was purchased from Lvsen Chemical Co., Ltd. (Linyi, China). Sodium hydroxide (NaOH, ≥96.0%) was obtained from Xilong Scientific Co., Ltd. (Shantou, China). Xanthan gum (XG, USP grade), urea (≥99.0%), ethylene glycol (≥98.0%), and 2-(2-butoxyethoxy)ethanol (CP grade) were obtained from Macklin Biochemical Technology Co., Ltd. (Shanghai, China). 0# diesel fuel was provided by China Petroleum & Chemical Co., Ltd. (Beijing, China).

2.2. Preparation of Foam Extinguishing Agent

The foam extinguishing agent was prepared by combining an additive concentrate and a surfactant concentrate. The additive concentrate comprised XG, urea, ethylene glycol, and 2-(2-butoxyethoxy)ethanol. The surfactant concentrate consisted of a PFH-BZ/OB-2 compounding system at a 1:2 molar ratio. A NaOH aqueous solution was used as a pH adjuster. In final foam fire extinguishing agent, the concentrations of the primary components were 2 mmol/L for PFH-BZ, 4 mmol/L for OB-2, and 0.02–0.10 wt.% for XG. A detailed preparation procedure is described in our previous work [31].

2.3. Experimental System and Procedures

2.3.1. Foam Fire Extinguishing Experiment

The fire extinguishing performance was investigated using a small-scale positive-pressure foam fire extinguishing system in accordance with GB 15308-2025 [28]. As shown in Figure 1, this experimental system comprises three primary components, including a foam generation system, a 500 × 500 × 100 mm3 oil pan, and a data acquisition system. According to ISO 7203-2019 [29], the system pressure and foam mass flow rate were controlled at 0.7 MPa and 750 g/min, respectively. Consequently, the liquid flow rate was adjusted to 45 L/h using a liquid rotameter, while the gas flow rate was maintained at a moderate value of 720 L/h via a gas rotameter. This configuration established a consistent gas–liquid ratio (GLR) of 16 throughout all tests, ensuring result comparability. During fire extinguishing, the flame morphology, temperature evolution, and post-suppression foam coverage were monitored and recorded. Specifically, the temperature measured 1 m above the center of the oil pan served as the primary thermal indicator, reflecting temperature variations throughout the fire extinguishing process.
Before the foam extinguishing experiment, the foaming capability and drainage characteristics were evaluated through expansion ratio and the 25% drainage time (t25%) according to ISO 7203-2019 [27,44]. For expansion ratio measurement, after stable foam generation for 30 s, foam was collected using a 250 mL foam collector. The mass of collected foam was determined by the mass difference of the collector before and after foam collection, as shown in Equation (1). Foam expansion ratio was calculated using Equation (2), which serves as a crucial indicator of foaming capability.
m f o a m = m a f t e r − m b e f o r e
E = ρ × V / m f o a m
where, mfoam is the mass of collected foam; mbefore and mafter are the mass values of the foam collector before and after foam collection, respectively; E is foam expansion ratio. ρ is the density of foam fire extinguishing agent, ρ = 1 g/mL; V is the volume of foam collector, V = 250 mL.
For drainage property evaluation, the collected foam was immediately transferred to the drainage property tester. As shown in Figure 2, the drainage property tester was pre-equilibrated at 50 °C via a thermostatic circulating water bath. A stopwatch was initiated when the first drained liquid was observed. The time required to drain 25% of mfoam was recorded as the t25%. This t25% parameter serves as a crucial indicator of foam stability and drainage characteristics under high-temperature conditions [45].
In the fire extinguishing experiment, 1 L 0# diesel fuel was added to the oil pan. After igniting, a 60 s pre-burn period was implemented to establish stable combustion conditions before foam application. The extinction time was defined as the interval from initial foam application to complete flame extinction. This parameter serves as a crucial quantitative indicator of foam fire extinguishing performance. In this study, effective extinguishment of foam fire extinguishing agents is defined as an extinction time of less than 3 min without reignition according to ISO 7203-2019 [29].

2.3.2. Biodegradation Test

The biodegradation of PFH-BZ surfactant solution at its cmc, optimal PFH-BZ foam fire extinguishing agent, and conventional 6% foam extinguishing agent (Quanzhou CA Fire Co., Ltd., Quanzhou, China) was assessed by determining the biochemical oxygen demand after 5 days (BOD5) and chemical oxygen demand (CODCr) [46,47]. The BOD5 was determined in accordance with HJ 505-2009 using river water as the microbial inoculum [48]. The seeded dilution water was prepared by mixing 50 mL river water with 5 L dilution water, where the latter contained pre-added nutrient solutions (1 mL 0.85 g/L KH2PO4 solution, 1 mL 11.00 g/L Mg2SO4 solution, and 1 mL 27.60 g/L CaCl2 solution). The sample solution was prepared at a 1:3 volume ratio of seeded dilution water to tested foam extinguishing agent. Then, the sample solutions were incubated for 5 days at 20 ± 1 °C using an L100-BOD biochemical incubator (Beijing Time Power Measure and Control Equipment Co., Ltd., Beijing, China), and gentle shaken twice daily. The 5-day incubation period is a standard requirement for BOD measurements, providing a consistent benchmark for assessing short-term biodegradability and ensuring comparability with other studies. Dissolved oxygen concentrations were measured before and after incubation using a JPSJ-605F dissolved oxygen meter (Inesa Scientific Instrument Co., Ltd., Shanghai, China). The BOD5 value was calculated using Equation (3).
B O D 5 = ∆ ρ 1 − ∆ ρ 0 × 1 − f 1 / f 1
where, Δρ1 and Δρ0 are the dissolved oxygen concentration differences before and after 5-day incubation for the sample solution and control solution, respectively; f1 is the fraction of the sample solution in the test mixture, f1 = 0.75.
The CODCr was determined in accordance with HJ 828-2017 [49]. The sample solution was formulated with 10 mL foam extinguishing agent, 5 mL 100.00 g/L HgSO4 solution, and 5 mL 0.025 mol/L K2Cr2O7 solution. Then the sample solution was subjected to gentle boiling reflux for 2 h using an LB-901A COD constant temperature heater (Loobo Environmental Protection Technology Co., Ltd., Qingdao, China). After cooling, the solution was titrated with 0.005 mol/L (NH4)2Fe(SO4)2 standard solution using ferroin (three drops) as the indicator. The titration endpoint was determined by the characteristic color transition from yellow through blue-green to reddish brown. The CODCr value was calculated according to Equation (4).
C O D C r = C × V 0 − V 1 × 8000 × f / V 2
where, C is the concentration of (NH4)2Fe(SO4)2 standard solution, C = 0.005 mol/L; V0 and V1 are the titrant volumes consumed by the blank and sample solutions, respectively; V2 is the volume of foam extinguishing agent, V2 = 10 mL; f is the dilution factor, f = 500.

3. Results and Discussions

3.1. Foaming Capability and Drainage Characteristics Analysis

The expansion ratio and t25% values of PFH-BZ foams at different XG concentrations are depicted in Figure 3. As shown in Figure 3a, the 0.02 wt.% XG foam exhibits excellent foaming performance with an expansion ratio of 27.8 ± 0.9. This value exceeds the theoretical value predicted by GLR (GLR + 1 = 17) by 63.5%, indicating a high gas–liquid mixing efficiency. This superior foaming capability stems from the generation of numerous microbubbles that fill the foam collector with higher packing density. Such enhanced foaming performance significantly improves fire control and suppression efficacy by accelerating foam spreading and accumulation on fuel surfaces. However, the expansion ratio gradually decreases with increasing XG concentration. When XG concentration exceeds 0.06 wt.%, the expansion ratio falls below the theoretical value predicted by GLR, exhibiting a 41.0–50.4% reduction compared to the PFH-BZ foam with 0.02 wt.% XG. This substantial decrease indicates that high XG concentrations disrupt the homogeneous mixing of foam solution and gas, thereby weakening foaming efficiency. Such deteriorated foaming performance will inevitably hinder the rapid spreading and coverage capabilities of PFH-BZ foam.
Regarding drainage performance, the PFH-BZ foam with 0.02 wt.% XG exhibits excellent foam stability under thermal and gravitational effects, achieving a t25% value of 191.0 ± 28.5 s. As XG concentration increases, the t25% value further extends by 41.1–273.5%, primarily attributed to its outstanding viscosity-increasing effect. As a double-helical polysaccharide rich in hydrophilic groups (–OH and –COOH), XG forms extensive three-dimensional network structures through intermolecular hydrogen bonding. These structures effectively constrain water mobility and increase solution viscosity, thereby inhibiting foam destabilization behaviors, including gravitational drainage, coarsening, and coalescence. This enhanced foam stability plays a crucial role in maintaining foam layer integrity during high-temperature fire suppression, directly enhancing isolating and smothering effects. However, it should be noted that excessive viscosity elevation may impede foam drainage, hindering the formation of spreadable aqueous films.
These findings collectively reveal that XG exerts dual effect on the foaming and drainage characteristics of PFH-BZ-based foam fire extinguishing agents. While higher XG concentrations markedly improve foam stability through viscosity enhancement, they simultaneously diminish foaming capacity and drainage performance, potentially hindering the formation of spreadable aqueous films. Therefore, a systematic evaluation of the optimal XG concentration is required to strike the best balance between these counteracting effects, thereby maximizing fire extinguishing efficacy.

3.2. Foam Suppression Process Analysis

The suppression process and post-suppression coverage of PFH-BZ foams with different XG concentrations are depicted in Figure 4. Upon foam application, all experimental conditions exhibit a transient increase in flame height, attributed to the instantaneous rupture and vaporization of foam under high temperatures. This process generates substantial steam expansion while enhancing oxygen entrainment and promoting diesel vapor diffusion, collectively intensifying combustion. As PFH-BZ foam is continuously discharged, it progressively accumulates on the high-temperature fuel surface, forming a central foam-covered zone and a peripheral combustion zone. Within the central zone, PFH-BZ foams exert multiple extinguishing effects, including cooling, thermal insulation, and oxygen smothering effects. These combined effects effectively interrupt heat transfer from surrounding flames, significantly suppressing diesel evaporation and combustion. As the foam layer progressively spreads, the central foam-covered zone expands while the peripheral combustion zone contracts. A concurrent decrease in flame height and color transition indicates a diminished combustion intensity. Sustained foam application continuously lowers diesel temperature until combustible vapor concentration becomes insufficient to sustain combustion, ultimately achieving complete extinguishment.
As shown in Figure 4, all PFH-BZ foams effectively extinguish diesel fires within 3 min, forming continuous foam layers without reignition. Notably, the 0.02 wt.% XG foam exhibits outstanding extinguishing performance with an extinction time of 35.4 s, despite demonstrating inferior foam coverage compared to higher XG concentration foams. This outstanding extinguishing efficacy stems from the excellent properties of 0.02 wt.% XG foam, including the generation of abundant stable foam and moderate drainage characteristics. These properties facilitate rapid foam spreading and aqueous film formation, synergistically enhancing cooling and smothering effects. However, increasing XG concentration diminishes fire extinguishing performance, as evidenced by longer extinction times. Higher XG concentrations negatively impact foam generation, spreading, and aqueous film formation. At 0.10 wt.% XG concentration, while the PFH-BZ foam achieves fire control within 30.0 s, its compromised spreading capability extends the extinction time by 21.1 s compared to the 0.02 wt.% XG foam. The longer extinction time not only increases foam consumption but also amplifies environmental contamination risks and potential economic losses.

3.3. Temperature Evolution Analysis

The temperature evolution at a height of 1 m during combustion and suppression processes of PFH-BZ foams with different XG concentrations is shown in Figure 5, with corresponding thermal parameters listed in Table 1. The results reveal that diesel achieves fully developed combustion within 20–30 s after ignition, leading to a sharp rise in temperature. For control condition without foam application, the temperature stabilizes at 750 °C with fluctuations after the pre-burn period due to restricted ventilation. The burning duration of the control condition is approximately 240 s.
For experimental conditions with foam application, the temperature evolution can be systematically divided into ignition, pre-burn, suppression, and cooling periods. During ignition and pre-burn periods, the foam-applied conditions exhibit temperature curves similar to that of the control condition. Upon foam application, the suppression period begins. During this stage, the temperature initially decreases due to foam vaporization and heat absorption, followed by a transient increase caused by intensified combustion. This transient temperature elevation serves as a critical performance indicator, reflecting the initial fire control capability, cooling, and insulating effects of foam. As detailed in Table 1, foam application induces an immediate temperature rise of 60.8–120.4 °C, representing a 9.7–23.6% increase relative to the temperature before foam application. Notably, the PFH-BZ foam with 0.02 wt.% XG exhibits minimal fire intensification, with a maximum temperature rise of 60.8 °C and a magnitude of 9.7%, indicating excellent cooling and insulating potential. This superior performance stems from optimal drainage, spreading, and coverage characteristics, which collectively facilitate rapid surface isolation and cooling. However, increasing XG concentration progressively compromises the foaming capacity, considerable drainage for aqueous film formation, and spreading performance of PFH-BZ foam, resulting in higher temperature increase. This increased temperature directly reflects a diminished initial cooling and suppression efficacy. Such performance limitations not only hinder rapid fire control but also exacerbate fuel evaporation, potentially triggering uncontrolled fire propagation and other hazards.
Following the establishment of effective foam coverage, the flame height and combustion area gradually decrease, resulting in a significant temperature reduction. Comparative analysis demonstrates that PFH-BZ foam with 0.02 wt.% XG exhibits the highest cooling rate, robustly confirming its exceptional cooling efficacy [50]. However, the cooling rate decreases with increasing XG concentration. The PFH-BZ foam containing 0.10 wt.% XG demonstrates a 28.0% reduction in average cooling rate compared to the 0.02 wt.% XG formulation. After complete flame extinction, all conditions enter the cooling stage without observed reignition, with temperatures gradually returning to ambient levels. In conclusion, the PFH-BZ foam containing 0.02 wt.% XG exhibits optimal comprehensive fire extinguishing performance, achieving an outstanding balance among foaming capacity, spreading performance, and moderate drainage characteristics.

3.4. Biodegradation Analysis

The BOD5 and CODCr values of PFH-BZ surfactant solution at its cmc, PFH-BZ foam fire extinguishing agent with 0.02 wt.% XG, and conventional 6% foam extinguishing agent are summarized in Table 2. The results reveal that the PFH-BZ solution exhibits a BOD5 value of 7.3 mg/L and a CODCr value of 220.0 mg/L, achieving a five-day biodegradation efficiency of 3.3%. However, when formulated into the PFH-BZ foam fire extinguishing agent, the CODCr substantially increases to 39,650.0 mg/L. This dramatic rise indicates that other components in the foam formulation, such as XG and other additives, also contribute to the total organic pollutant load. This finding further highlights the importance of not only developing PFAS alternatives but also optimizing the composition of eco-friendly foam extinguishing agents to minimize environmental impact and enhance biocompatibility.
Compared to conventional foam, the optimal PFH-BZ foam fire extinguishing agent exhibits a 53.1% reduction in CODCr and a 461.5% increase in BOD5. These pronounced differences indicate that the PFH-BZ agent contains a higher proportion of biodegradable organic compounds, thereby reducing the total organic pollution burden. This enhanced biodegradability potentially decreases the complexity and cost of post-disaster wastewater treatment processes. These promising results suggest that through formulation optimization, this novel PFH-BZ foam extinguishing agent possesses significant potential to achieve further reductions in environmental impact while maintaining effective fire suppression performance.

3.5. Mechanism of XG Influence on PFH-BZ Foam Fire Extinguishing Performance

Considering the combined effects of XG on the physicochemical properties and fire extinguishing performance of PFH-BZ foam, a comprehensive mechanism of its influence is further proposed. As shown in Figure 6, under the radiative (Qrad) and convective (Qconv) heat transfer, the surface temperature (Ts) and vapor pressure (Pv) of diesel rapidly increase [51]. During this stage, diesel fuel continuously evaporates at a mass rate of m f u e l ˙ , with subsequent vapor ignition under high temperatures, establishing a self-sustaining combustion feedback cycle. During foam application, ambient-temperature (Ti) foam is discharged onto the diesel surface at a mass flow rate of m a d d ˙ and rapidly spreads at a velocity of Vs to form a foam layer of a thickness h. Progressive foam accumulation and spreading reduce the combustion area. Complete surface coverage effectively isolates the fuel from atmospheric oxygen, thereby exerting the smothering extinguishing effect. Simultaneously, the liquid phase of the foam continuously evaporates at a mass flow rate of m e v a p ˙ under thermal exposure and drains at a mass flow rate of m d r a i n ˙ . These endothermic processes of liquid evaporation and drainage continuously extract thermal energy from the flames and fuel, thereby exerting the cooling extinguishing effect. After complete flame extinguishment, continuous foam application is necessary to maintain sufficient layer thickness to prevent fuel reignition, ensuring the persistence of isolating extinguishing effect.
Increasing XG concentration significantly enhances foam stability, prolonging foam layer integrity on the high-temperature fuel surface and thus extending the effective duration of smothering and isolating effects. However, higher XG addition introduces several detrimental effects. Firstly, the increased solution viscosity compromises gas dispersion efficiency and weakens foaming capacity, directly reducing foam coverage and smothering efficacy. Secondly, the high viscosity significantly impedes foam spreading across the fuel surfaces, reducing Vs and delaying rapid coverage of burning areas [52]. More critically, while the formation of hydrogen-bond networks enhances foam film stability, it concurrently retards foam drainage. This inhibition delays the formation of spreadable aqueous film, which is essential for rapid surface cooling, thereby diminishing the cooling efficacy of PFH-BZ foam. These combined effects collectively prevent PFH-BZ foams from achieving rapid and efficient coverage of the combustion zone during the suppression period. The consequent delay in aqueous film formation further compromises smothering and cooling effects. These factors ultimately prolong extinction times and reduce overall fire extinguishing efficiency.

4. Conclusions

This study systematically investigates the influence of XG on the fire extinguishing performance of foam extinguishing agents formulated with short-chain fluorocarbon surfactant (PFH-BZ). The results reveal that introduction of XG significantly enhances foam stability while concomitantly reducing foaming capacity, evidenced by increased t25% and decreased expansion ratio with rising XG concentrations. The PFH-BZ foam containing 0.02 wt.% XG exhibits optimal performance, achieving an expansion ratio of 27.8 and a t25% of 191.0 s. This formulation demonstrates superior fire extinguishing characteristics, including a minimal transient temperature rise of 60.8 °C upon foam application, the highest cooling rate of 16.80 °C/s, and rapid fuel surface coverage, leading to complete flame extinguishment in only 35.4 s. This outstanding performance is primarily attributed to the synergistic balance among foaming, drainage, and spreading properties at this optimal XG concentration, which facilitates rapid fuel surface coverage and the formation of a critical cooling aqueous film. However, an excessive concentration of XG adversely affects the fire extinguishing performance of PFH-BZ foam. At an XG concentration of 0.10 wt.%, while foam stability improves dramatically, with a t25% of 713.3 s, the expansion ratio significantly decreases by 50.4% compared to the optimal formulation. This phenomenon results in compromised fire extinguishing efficiency, characterized by an increased transient temperature rise of 83.2 °C, a reduced cooling rate of 12.1 °C/s, a delayed fuel coverage time of over 20 s, and a prolonged extinction time of 56.5 s. Biodegradability assessments reveal that the optimal PFH-BZ foam exhibits a 461.5% increase in BOD5 and a 53.1% decrease in CODCr compared to conventional synthetic foam, indicating reduced organic pollution potential and considerable environmental compatibility. This study confirms the feasibility of developing eco-friendly PFH-BZ foam fire extinguishing agents by optimizing XG concentration, achieving an optimal balance among foam stability, drainage characteristics, and spreading dynamics, leading to efficient fire suppression through combining cooling, smothering, and isolating effects. Future studies should focus on further formulation optimization to enhance environmental friendliness while maintaining superior fire extinguishing performance.

Author Contributions

Conceptualization, Z.X.; methodology, W.Z.; software, L.Y.; validation, W.Z.; formal analysis, W.Z.; investigation, W.Z.; resources, L.Y.; data curation, W.Z.; writing—original draft preparation, W.Z.; writing—review and editing, L.Y.; visualization, W.Z.; supervision, L.Y.; project administration, Z.X.; funding acquisition, L.Y. and Z.X. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China under Nos. 52176146 and 52474279, the Opening Fund of State Key Laboratory of Fire Science (SKLFS) under Grant No. HZ2025-KF04, the Science and Technology Innovation Program of Hunan Province under Grant No. 2025RC3039, and the Fundamental Research Funds for the Central Universities of Central South University under No. 2023ZZTS0367.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Fadeyibi, I.O.; Jewo, P.I.; Opoola, P.; Babalola, O.S.; Ugburo, A.; Ademiluyi, S.A. Burns and Fire Disasters from Leaking Petroleum Pipes in Lagos, Nigeria: An 8-Year Experience. Burns 2011, 37, 145–152. [Google Scholar] [CrossRef]
  2. Zanganeh, J.; Moghtaderi, B.; Ishida, H. Combustion and flame spread on fuel-soaked porous solids. Prog. Energy Combust. Sci. 2013, 39, 320–339. [Google Scholar] [CrossRef]
  3. Chen, J.; Lei, S.; Wang, T.; Huang, Y.; Kong, D.; Luo, Z. Experimental and Numerical Investigation into Burning Rate and Fire Plume Characteristic of Pool Fire with Plate Obstacle. Process Saf. Environ. Prot. 2024, 184, 1459–1467. [Google Scholar] [CrossRef]
  4. Okamoto, K.; Yamasaki, H.; Matsuoka, I.; Ichikawa, T.; Matsuoka, H.; Saeki, Y.; Honma, M. Burning behavior and fire hazards of petroleum liquid combustible spills. J. Loss Prev. Process Ind. 2024, 90, 105346. [Google Scholar] [CrossRef]
  5. Dlugogorski, B.Z.; Schaefer, T.H. Compatibility of aqueous film-forming foams (AFFF) with sea water. Fire Saf. J. 2021, 120, 103288. [Google Scholar] [CrossRef]
  6. Zabelin, I.V.; Shkola, M.V.; Shlegel, N.E.; Strizhak, P.A. Using Hydrate Foam to Extinguish Petroleum Product Tank Fires. J. Loss Prev. Process Ind. 2025, 98, 105730. [Google Scholar] [CrossRef]
  7. Shevchenko, R.I.; Strelets, V.M.; Loboichenko, V.M.; Pruskyi, A.V.; Myroshnyk, O.N.; Kamyshentsev, G.V. REVIEW OF UP-TO-DATE APPROACHES FOR EXTINGUISHING OIL AND PETROLEUM PRODUCTS. SOCAR Proc. 2021, 1, 169–174. [Google Scholar] [CrossRef]
  8. Lou, M.; Jia, H.; Lin, Z.; Zeng, D.; Huo, J. Study on Fire Extinguishing Performance of Different Foam Extinguishing Agents in Diesel Pool Fire. Results Eng. 2023, 17, 100874. [Google Scholar] [CrossRef]
  9. Kim, T.S.; Park, T.H.; Park, J.H.; Yang, J.H.; Han, D.H.; Lee, B.C.; Kwon, J.S. Thermal Characteristics of Fire Extinguishing Agents in Compartment Fire Suppression. Sci. Prog. 2024, 107, 1–16. [Google Scholar] [CrossRef]
  10. Rie, D.H.; Lee, J.W.; Kim, S. Class B Fire-Extinguishing Performance Evaluation of a Compressed Air Foam System at Different Air-to-Aqueous Foam Solution Mixing Ratios. Appl. Sci. 2016, 6, 191. [Google Scholar] [CrossRef]
  11. Xu, Z.; Guo, X.; Yan, L.; Kang, W. Fire-Extinguishing Performance and Mechanism of Aqueous Film-Forming Foam in Diesel Pool Fire. Case Stud. Therm. Eng. 2020, 17, 100578. [Google Scholar] [CrossRef]
  12. Brunn, H.; Arnold, G.; Körner, W.; Rippen, G.; Steinhäuser, K.G.; Valentin, I. PFAS: Forever Chemicals—Persistent, Bioaccumulative and Mobile. Reviewing the Status and the Need for Their Phase out and Remediation of Contaminated Sites. Environ. Sci. Eur. 2023, 35, 20. [Google Scholar] [CrossRef]
  13. Douglas, G.B.; Vanderzalm, J.L.; Williams, M.; Kirby, J.K.; Kookana, R.S.; Bastow, T.P.; Bauer, M.; Bowles, K.C.; Skuse, D.; Davis, G.B. PFAS Contaminated Asphalt and Concrete—Knowledge Gaps for Future Research and Management. Sci. Total Environ. 2023, 887, 164025. [Google Scholar] [CrossRef]
  14. Alsadik, A.; Akintunde, O.O.; Habibi, H.R.; Achari, G. PFAS in Water Environments: Recent Progress and Challenges in Monitoring, Toxicity, Treatment Technologies, and Post-Treatment Toxicity. Environ. Syst. Res. 2025, 14, 18. [Google Scholar] [CrossRef]
  15. Steenland, K.; Kugathasan, S.; Barr, D.B. PFOA and ulcerative colitis. Environ. Res. 2018, 165, 317–321. [Google Scholar] [CrossRef]
  16. Ehsan, M.N.; Riza, M.; Pervez, M.N.; Khyum, M.M.O.; Liang, Y.; Naddeo, V. Environmental and Health Impacts of PFAS: Sources, Distribution and Sustainable Management in North Carolina (USA). Sci. Total Environ. 2023, 878, 163123. [Google Scholar] [CrossRef]
  17. Elgarahy, A.M.; Eloffy, M.G.; Saber, A.N.; Abouzid, M.; Rashad, E.; Ghorad, M.A.; El-Sherif, D.; Elwakeel, K.Z. Exploring the sources, occurrence, transformation, toxicity, monitoring, and remediation strategies of per- and polyfluoroalkyl substances: A review. Environ. Monit. Assess. 2024, 196, 1209. [Google Scholar] [CrossRef] [PubMed]
  18. Mojiri, A.; Zhou, J.L.; Ozaki, N.; KarimiDermani, B.; Razmi, E.; Kasmuri, N. Occurrence of per- and polyfluoroalkyl substances in aquatic environments and their removal by advanced oxidation processes. Chemosphere 2023, 330, 138666. [Google Scholar] [CrossRef] [PubMed]
  19. Brennan, N.M.; Evans, A.T.; Fritz, M.K.; Peak, S.A.; von Holst, H.E. Trends in the Regulation of Per-and Polyfluoroalkyl Substances (PFAS): A Scoping Review. Int. J. Environ. Res. Public Health 2021, 18, 10900. [Google Scholar] [CrossRef] [PubMed]
  20. Back, G.G. Aqueous Film Forming Foam (AFFF) Status and Alternatives: The Big Picture (2024 Status Update). Fire Technol. 2024, 60, 2019–2040. [Google Scholar] [CrossRef]
  21. Jahura, F.T.; Mazumder, N.U.S.; Hossain, M.T.; Kasebi, A.; Girase, A.; Ormond, R.B. Exploring the Prospects and Challenges of Fluorine-Free Firefighting Foams (F3) as Alternatives to Aqueous Film-Forming Foams (AFFF): A Review. ACS Omega 2024, 9, 37430–37444. [Google Scholar] [CrossRef] [PubMed]
  22. Malik, P.; Nandini, D.; Tripathi, B.P. Firefighting Aqueous Film Forming Foam Composition, Properties and Toxicity: A Review. Environ. Chem. Lett. 2024, 22, 2013–2033. [Google Scholar] [CrossRef]
  23. Olsen, G.W.; Chang, S.C.; Noker, P.E.; Gorman, G.S.; Ehresman, D.J.; Lieder, P.H.; Butenhoff, J.L. A Comparison of the Pharmacokinetics of Perfluorobutanesulfonate (PFBS) in Rats, Monkeys, and Humans. Toxicology 2009, 256, 65–74. [Google Scholar] [CrossRef]
  24. Darmanin, T.; Guittard, F. Superoleophobic surfaces with short fluorinated chains? Soft Matter 2013, 9, 5982–5990. [Google Scholar] [CrossRef]
  25. Hagenaars, A.; Meyer, I.J.; Herzke, D.; Pardo, B.G.; Martinez, P.; Pabon, M.; De Coen, W.; Knapen, D. The Search for Alternative Aqueous Film Forming Foams (AFFF) with a Low Environmental Impact: Physiological and Transcriptomic Effects of Two Forafac® Fluorosurfactants in Turbot. Aquat. Toxicol. 2011, 104, 168–176. [Google Scholar] [CrossRef]
  26. Peshoria, S.; Nandini, D.; Tanwar, R.K.; Narang, R. Short-chain and long-chain fluorosurfactants in firefighting foam: A review. Environ. Chem. Lett. 2020, 18, 1277–1300. [Google Scholar] [CrossRef]
  27. Zhao, W.; Xu, Z.; Yan, L. Zwitterionic Short-Chain Fluorocarbon Surfactant: Synthesis, Synergy with Hydrocarbon Surfactants, and Effects of Inorganic Salts on Surface Activity and Foam Performance. Surf. Interfaces 2025, 72, 107125. [Google Scholar] [CrossRef]
  28. GB 15308-2025; Foam Extinguishing Agent. Standardization Administration of the People’s Republic of China: Beijing, China, 2025.
  29. ISO 7203-2019; Fire Extinguishing Media-Foam Concentrates. International Organization for Standardization: Geneva, Switzerland, 2019.
  30. Zhao, W.; Xu, Z.; Yan, L. Competitive Adsorption and Gas Diffusion Inhibition Effect between Long-Chain Alcohol and Short-Chain Fluorocarbon Surfactant in Foam Solution. Colloids Surf. A Physicochem. Eng. Asp. 2025, 726, 137777. [Google Scholar] [CrossRef]
  31. Zhao, W.; Zhu, Z.; Xu, Z.; Yan, L. Polysaccharides and Polyacrylamide as Linear Polymeric Stabilizers for Zwitterionic Short-Chain Fluorocarbon Surfactant: Interfacial Properties, Apparent Viscosity, and Foam Performance. Polymers 2025, 17, 3112. [Google Scholar] [CrossRef]
  32. Bhat, I.M.; Wani, S.M.; Mir, S.A.; Masoodi, F.A. Advances in Xanthan Gum Production, Modifications and Its Applications. Biocatal. Agric. Biotechnol. 2022, 42, 102328. [Google Scholar] [CrossRef]
  33. Raj, S.; Krishnan, J.M.; Ramamurthy, K. Influence of admixtures on the characteristics of aqueous foam produced using a synthetic surfactant. Colloids Surf. A Physicochem. Eng. Asp. 2022, 643, 128770. [Google Scholar] [CrossRef]
  34. Baigadilov, A.; Colombano, S.; Omirbekov, S.; Cochennec, M.; Davarzani, D.; Lion, F.; Bodiguel, H.; Oxarango, L. Stability and flow behavior of polymer-enhanced foams for improved in-situ remediation of hydrocarbons: Effect of polymer-surfactant interactions. J. Loss Prev. Process Ind. 2025, 486, 137004. [Google Scholar] [CrossRef]
  35. Li, H.; Yu, X.; Fu, Z.; Lu, S. Stabilization Mechanisms of Foams Enhanced by Xanthan Gum and Sodium Carboxymethyl Cellulose: Rheology–Bubble Structure Interplay and Predictive Criteria for Drainage Delays. Carbohydr. Polym. 2025, 366, 123901. [Google Scholar] [CrossRef] [PubMed]
  36. Carrier, V.; Colin, A. Coalescence in Draining Foams. Langmuir 2003, 19, 4535–4538. [Google Scholar] [CrossRef]
  37. Shankaran, P.I.; Chinnaswamy, A. Instant Coffee Foam: An Investigation on Factors Controlling Foamability, Foam Drainage, Coalescence, and Disproportionation. J. Food Process Eng. 2019, 42, e13173. [Google Scholar] [CrossRef]
  38. Saha, S.; Bhaumik, S.; Roy, A. Coupling between Drainage and Coarsening in Wet Foam. Pramana—J. Phys. 2009, 72, 1037–1044. [Google Scholar] [CrossRef]
  39. Fan, X.; Ma, L.; Sheng, Y.; Liu, X.; Wei, G.; Liu, S. Experimental Investigation on the Characteristics of XG/GG/HPAM Gel Foam and Prevention of Coal Spontaneous Combustion. Energy 2023, 284, 128710. [Google Scholar] [CrossRef]
  40. Yan, B.; Zhu, G.; Liu, C.; Hu, X.; Zhong, F.; He, L.; Liu, T.; Peng, M. Preparation and Properties of a Fluorine-Free Aerogel Foam Extinguishing Agent. Colloids Surf. A Physicochem. Eng. Asp. 2025, 707, 135826. [Google Scholar] [CrossRef]
  41. Kang, W.; Zhang, Z.; Zhou, Q.; Xing, Y.; Lu, Y. Preparation of Environmental-Friendly Foam Extinguishing Agent Based on Inorganic Salt and Polysaccharide Mixtures for Firefighting Diesel Pool Fire. J. Build. Eng. 2025, 102, 111992. [Google Scholar] [CrossRef]
  42. Naji, S.; Razavi, S.M.A. Functional and textural characteristics of cress seed (Lepidium sativum) gum and xanthan gum: Effect of refrigeration condition. Food Biosci. 2014, 5, 1–8. [Google Scholar] [CrossRef]
  43. Yu, X.; Li, F.; Miao, X.; Jiang, N.; Zong, R.; Lu, S.; Li, C. Experimental Investigation on the Spread of Aqueous Foam over Ethanol Surface. Chin. J. Chem. Eng. 2020, 28, 2946–2954. [Google Scholar] [CrossRef]
  44. Ates, A.; Madsen, M.D.; Long, T.E.; Qiao, R.; Lattimer, B.Y. Designing surfactants for fuel resistance: Linking foam stability, micelle behavior, and molecular architecture. Colloids Surf. A Physicochem. Eng. Asp. 2025, 727, 138413. [Google Scholar] [CrossRef]
  45. Schofield, H.K.; Megson, D.P.; Da Costa, J.; Richardson, L.A.; Shelbourne, K.; Payne, J. Fluorosurfactant Retention in the Foam Blanket during Gravitational Drainage of an Aqueous Film-Forming Foam. Colloid Interface Sci. Commun. 2021, 42, 100404. [Google Scholar] [CrossRef]
  46. Bourgeois, A.; Bergendahl, J.; Rangwala, A. Biodegradability of Fluorinated Fire-Fighting Foams in Water. Chemosphere 2015, 131, 104–109. [Google Scholar] [CrossRef]
  47. Maza-Márquez, P.; Vílchez-Vargas, R.; González-Martínez, A.; González-López, J.; Rodelas, B. Assessing the Abundance of Fungal Populations in a Full-Scale Membrane Bioreactor (MBR) Treating Urban Wastewater by Using Quantitative PCR (QPCR). J. Environ. Manag. 2018, 223, 1–8. [Google Scholar] [CrossRef]
  48. HJ 505-2009; Water Quality—Determination of Biochemical Oxygen Demand After 5 Days (BOD5) for Dilution and Seeding Method. Ministry of Ecology and Environment of the People’s Republic of China: Beijing, China, 2009.
  49. HJ 828-2018; Water quality—Determination of the Chemical Oxygen Demand—Dichromate Method. Ministry of Ecology and Environment of the People’s Republic of China: Beijing, China, 2017.
  50. Gałaj, J.; Tuśnio, N.; Wolny, P.; Drzymała, T. Analysis of the Impact of Water Flow Rate on the Temperature Variability in a Closed Room during the Extinguishing of A-Group Fire Using a Hybrid Water Mist Suppression System. Sustainability 2020, 12, 8700. [Google Scholar] [CrossRef]
  51. Scheffey, J.L. Foam Agents and AFFF System Design Considerations. In SFPE Handbook of Fire Protection Engineering, 5th ed.; Hurley, M.J., Gottuk, D., Eds.; Springer: New York, NY, USA, 2016; pp. 1646–1706. [Google Scholar]
  52. Dahlbom, S.; Mallin, T.; Bobert, M. Fire Test Performance of Eleven PFAS-Free Class B Firefighting Foams Varying Fuels, Admixture, Water Types and Foam Generation Techniques. Fire Technol. 2022, 58, 1639–1665. [Google Scholar] [CrossRef]
Fire 08 00463 g001
Figure 1. Schematic of small-scale positive-pressure foam fire extinguishing system.
Figure 1. Schematic of small-scale positive-pressure foam fire extinguishing system.
Fire 08 00463 g001
Fire 08 00463 g002
Figure 2. Schematic of foam drainage property tester.
Figure 2. Schematic of foam drainage property tester.
Fire 08 00463 g002
Fire 08 00463 g003
Figure 3. Expansion ratio and t25% values of PFH-BZ foam with different XG concentrations: (a) expansion ratio and (b) t25%.
Figure 3. Expansion ratio and t25% values of PFH-BZ foam with different XG concentrations: (a) expansion ratio and (b) t25%.
Fire 08 00463 g003
Fire 08 00463 g004
Figure 4. Suppression process and post-suppression coverage of PFH-BZ foams with different XG concentrations.
Figure 4. Suppression process and post-suppression coverage of PFH-BZ foams with different XG concentrations.
Fire 08 00463 g004
Fire 08 00463 g005
Figure 5. Temperature evolution at a height of 1 m during (a) combustion and (b) suppression processes of PFH-BZ foams with different XG concentrations (The star corresponds to the moment when the flame is completely extinguished).
Figure 5. Temperature evolution at a height of 1 m during (a) combustion and (b) suppression processes of PFH-BZ foams with different XG concentrations (The star corresponds to the moment when the flame is completely extinguished).
Fire 08 00463 g005
Fire 08 00463 g006
Figure 6. Schematic of foam suppression mechanism.
Figure 6. Schematic of foam suppression mechanism.
Fire 08 00463 g006
Table 1. Characteristic thermal parameters of PFH-BZ foams with different XG concentrations.
Table 1. Characteristic thermal parameters of PFH-BZ foams with different XG concentrations.
XG Concentration
/(wt.%)		Maximum Temperature
Rise/(°C)		Maximum Temperature
Rise Magnitude/(%)		Average Cooling
Rate/(°C/s)
0.0260.89.716.8
0.04120.423.614.2
0.0680.514.114.4
0.0889.114.313.9
0.1083.214.412.1
Table 2. BOD5 and CODCr of PFH-BZ and conventional foam extinguishing agents.
Table 2. BOD5 and CODCr of PFH-BZ and conventional foam extinguishing agents.
SampleBOD5/(mg/L)CODCr/(mg/L)
PFH-BZ surfactant at cmc7.3220.0
PFH-BZ foam extinguishing agent with 0.02 wt.% XG7.339,650.0
Conventional 6% foam extinguishing agent1.384,500.0
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Zhao, W.; Xu, Z.; Yan, L. Optimizing Xanthan Gum for Enhanced Fire Extinguishing Performance of Eco-Friendly Short-Chain Fluorocarbon Surfactant Foam. Fire 2025, 8, 463. https://doi.org/10.3390/fire8120463

AMA Style

Zhao W, Xu Z, Yan L. Optimizing Xanthan Gum for Enhanced Fire Extinguishing Performance of Eco-Friendly Short-Chain Fluorocarbon Surfactant Foam. Fire. 2025; 8(12):463. https://doi.org/10.3390/fire8120463

Chicago/Turabian Style

Zhao, Wenjun, Zhisheng Xu, and Long Yan. 2025. "Optimizing Xanthan Gum for Enhanced Fire Extinguishing Performance of Eco-Friendly Short-Chain Fluorocarbon Surfactant Foam" Fire 8, no. 12: 463. https://doi.org/10.3390/fire8120463

APA Style

Zhao, W., Xu, Z., & Yan, L. (2025). Optimizing Xanthan Gum for Enhanced Fire Extinguishing Performance of Eco-Friendly Short-Chain Fluorocarbon Surfactant Foam. Fire, 8(12), 463. https://doi.org/10.3390/fire8120463

Article Metrics

Back to TopTop