Environmental modulation enhances benzene phytoremediation by Aglaonema and Dracaena in indoor settings

Abstract

Indoor air pollution remains a pressing public health challenge, with volatile organic compounds (VOCs) from household materials contributing to respiratory dysfunctions, neurological disorders, and increased carcinogenic risk. Among these, benzene poses a particular threat due to its established links to hematological malignancies. Addressing this issue requires scalable, low-energy purification strategies. Experiments were conducted in controlled environmental chambers using Aglaonema black and Dracaena deremensis to assess benzene removal under varying temperature and humidity conditions. This study introduces an experimental framework to assess how temperature and humidity modulate benzene phytoremediation by ornamental plants under controlled conditions. In sealed 1 m³ chambers, Aglaonema black reduced benzene levels by 92% (from 0.125 to 0.01 ppm) within 12 h., while Dracaena deremensis performed optimally at 50% humidity. These findings emphasize the importance of environmental calibration in maximizing VOC uptake and underscore the feasibility of plant-based air purification as an energy-efficient alternative to conventional technologies. This study offers a novel predictive framework that integrates environmental parameters into plant-based VOC removal modeling, enabling future application in smart building air quality systems. Further work is warranted to explore long-term performance, plant–microbe–environment interactions, and integration into architectural systems for real-world deployment. These findings support the integration of ornamental plants into smart buildings and urban air quality management strategies.

Introduction

Indoor air pollution has emerged as a critical and often underestimated determinant of public health, especially given that individuals spend up to 90% of their time indoors—where pollutant concentrations frequently exceed those found outdoors^1,2. Benzene is one of the most critical VOCs found indoors. It is a known carcinogen and is linked to blood-related disorders such as leukemia, even at sub-threshold concentrations^2–4.

Conventional air purification technologies, including high-efficiency particulate air (HEPA) filters and activated carbon adsorption systems, are effective but often suffer from high operational costs, energy demands, and the need for regular maintenance^5,6.

In this context, phytoremediation—using plants to remove pollutants—has emerged not only as a complementary method but as a potentially transformative and sustainable alternative⁷.

Previous studies have documented the VOC removal potential of various ornamental species, such as Aglaonema spp., Nephrolepis obliterata, Epipremnum aureum, and Chlorophytum comosum, under controlled conditions^8,9. However, their broader application remains limited, in part due to experimental designs that consider environmental variables—such as temperature (T) and relative humidity (RH)—in isolation, rather than in combination. Furthermore, plant-based VOC removal is rarely integrated into mainstream architectural or regulatory frameworks, partly due to a lack of predictive models and real-world performance data¹⁰.

While multiple studies have independently assessed the effects of T and RH on phytoremediation efficiency^7,8,11–13 , comprehensive analyses that integrate these variables remain scarce. Additionally, little is known about how prolonged benzene exposure may affect plant health, potentially compromising remediation performance over time^14,15.To fully realize the potential of phytoremediation, it is essential to develop predictive frameworks that integrate environmental variability with species-specific physiological traits, particularly within data-rich, sensor-driven smart environments¹⁶.

Recent studies have emphasized the sensitivity of VOC uptake processes—such as stomatal conductance and transpiration rates—to environmental conditions^17,18.

Accordingly, this study aims to:

1. quantify species-specific benzene removal efficiencies under varying RH–T regimes;

2. elucidate the mechanistic contributions of key environmental variables; and guide the design of optimized, plant-based indoor air purification systems suited for dynamic built environments¹⁸. Despite the effectiveness of conventional technologies, their sustainability limitations underscore the need for alternative strategies—such as phytoremediation^11,18.

Materials and methods

Plant material and growth conditions

Plants were sourced from a certified horticultural supplier (Mahallati Flower Market, Tehran) and acclimatized under controlled indoor conditions for three months to stabilize physiological responses^9,19. A total of three pots per species (n = 3) were used during each treatment, consistent with the triplicate sampling design. This sample size (n = 3) is consistent with previous controlled-environment phytoremediation studies (e.g.,^9,17,21) and provides sufficient statistical power under standardized experimental conditions. Given the highly controlled nature of the experimental chambers, biological variability was minimized, allowing for reliable interspecies comparison. All plants were of similar size and age at the start of the experiment to minimize variability in foliar surface area and physiological performance.

Environmental conditions during acclimatization were maintained as follows:

• Light intensity: 1000 ± 50 lx (at canopy level)

• Temperature: 21.5 ± 2.3°C

• Relative humidity: 50 ± 5%

Plants were irrigated with distilled water every 48 h to avoid drought stress and ensure physiological consistency. Distilled water was used to eliminate variability in nutrient or contaminant content that might be present in tap water, ensuring controlled and reproducible environmental conditions across all replicates. Foliage was gently rinsed twice weekly to remove particulate matter, thereby preserving stomatal function. To isolate aerial benzene uptake and minimize microbial interference, all pots and soil surfaces were sealed with polyethylene film, taking care to prevent root protrusion. Although complete sterilization was not feasible, this approach significantly reduced rhizospheric microbial activity and enabled a more accurate assessment of shoot-level VOC removal. Future studies are encouraged to use sterilized substrates or conduct microbial profiling to better isolate plant-specific uptake mechanisms.

Future studies should consider sterilized substrates or microbial profiling to better isolate plant-specific uptake mechanisms. Light intensity was held constant to prevent confounding effects on gas exchange and transpiration, allowing isolated assessment of temperature and humidity influences.

Experimental chamber design and leak validation

Phytoremediation experiments were conducted in custom-fabricated Plexiglas chambers (internal volume: 1.00 ± 0.02 m³), designed to replicate typical indoor environments while enabling precise environmental control. All joints were sealed with BTEX-free silicone to eliminate exogenous VOC contamination.

Three complementary tests were performed to validate chamber airtightness:

• Pressure Decay Test: Chambers were pressurized to +10 mbar; pressure loss was monitored using a Testo 512 manometer (±0.5 mbar). Acceptable sealing was confirmed by pressure drops below 1.0 mbar over 30 minutes.

• CO₂ Tracer Gas Test: CO₂ was introduced, and leakage was assessed using a Testo 535 CO₂ meter. No external increase in CO₂ was detected during 2-hour observation periods.

Smoke Visualization Test: Smoke was applied at seals and joints. No air movement or leakage was observed. The experimental chamber design is both scalable and reproducible, providing a robust platform for standardized VOC phytoremediation assessments across different plant species and environmental conditions. Each chamber contained a single plant specimen at a time to prevent inter-plant variability, and all tests were conducted independently per replicate.

Environmental monitoring and control

Temperature and relative humidity were continuously monitored using a calibrated Sensirion SHT35 sensor (accuracy: ± 0.2°C, ± 1.5% RH), placed at canopy level and interfaced with a HOBO UX100 data logger. Conditions were maintained at:

• Temperature: 22.0 ± 1.2°C

• Relative humidity: 50 ± 3%

An integrated humidifier/dehumidifier and thermal control system was used to sustain target parameters.

Benzene dosing and exposure conditions

Benzene vapor was introduced using a precision Hamilton 1000 Series gas-tight syringe (Model 1001 LT, ± 1 µL). Target concentrations (0.125–1.000 ppm) were selected to simulate realistic indoor exposures. Calibration runs in plant-free chambers were conducted to validate dosing accuracy via GC-FID, with an error margin < 2.5%.

Benzene was injected into the sealed chamber through a silicone-sealed port, followed by 2 min of internal air circulation to ensure homogeneous distribution. Control tests indicated natural decay of 6.3 ± 0.9% over 24 h, attributable to minor adsorption or leakage, and this background was subtracted from plant-associated removal values.

Sampling, analysis, and removal efficiency calculation

Benzene concentrations were analyzed using a Varian CP-3800 gas chromatograph with Flame Ionization Detector (GC-FID) and CP-Sil 13CB column (25 m × 0.25 mm × 0.25 μm). Parameters were as follows:

• Injector: 200°C

• Detector: 220°C

• Oven: 40°C (1 min), ramped to 42°C at 0.5°C/min (hold 3 min)

• Carrier gas: Nitrogen, 1.5 mL/min

Air samples were drawn using a 50 mL Hamilton Super Syringe via self-sealing septa, avoiding pressure changes. Each sample was analyzed in triplicate within 30 s of extraction.

Calibration curves were generated from certified benzene standards (Sigma-Aldrich) across five concentration points (0.1–1.0 ppm), with R² = 0.9987. The limit of detection (LOD) was 0.005 ppm.

Removal Efficiency (RE) was calculated as:

1

where: RE = Removal Efficiency (mg/m³·h), C_i, C_f = Initial and final benzene concentrations (ppm), F = Conversion factor (ppm to mg/m³), V = Chamber volume (m³), T = Exposure duration (h).

Conversion from ppm to mg/m³ used the ideal gas law:

where: C: Concentration in mg/m³, ppm: Parts per million of benzene, M: Molar mass of benzene = 78.11 g/mol, 24.45: Molar volume of ideal gas at 25°C and 1 atm (L/mol).

Statistical analysis

All treatments were performed in biological triplicates (n = 3). Triplicate GC-FID readings were averaged for each time point. Data normality and variance homogeneity were validated using Shapiro–Wilk and Levene’s tests, respectively. A three-way ANOVA was employed to assess the effects of species, temperature, and humidity. Repeated-measures ANOVA was used for time-series data. Post hoc comparisons were conducted using Tukey’s HSD.

Statistical significance was set at α = 0.05. Analyses were performed using SPSS v17.0, and graphs were generated via GraphPad Prism 9.0.

Results and discussion

Phytoremediation efficiency and comparative analysis

The benzene removal capacity of Aglaonema black and Dracaena deremensis was quantitatively assessed under controlled exposure scenarios. At an initial benzene concentration of 0.25 ppm, Aglaonema black reduced ambient levels to 0.016 ppm, representing a 92% decrease. Compared to conventional adsorption methods like activated carbon—which typically achieve ~ 90% benzene removal at considerably higher cost and maintenance needs—Aglaonema 'Black' reached similar removal efficiencies (~ 92%) with no energy input and minimal upkeep, highlighting its potential as a low-cost and sustainable alternative (Fig. 1). As shown in Fig. 1, Aglaonema black consistently reduced benzene concentrations more effectively than Dracaena across both exposure levels.

Fig. 1.

Efficiency of benzene removal by aglaonema black and dracaena deremensis under varying concentration levels.

In contrast, Dracaena deremensis exhibited a lower removal efficiency, with final concentrations of 0.096 ppm—indicating only a 61% reduction under identical conditions. These findings are statistically significant (p < 0.05) and underscore the superior uptake dynamics of Aglaonema, likely driven by its physiological resilience and rapid stomatal response.

At a lower concentration (0.125 ppm), the performance gap narrowed; however, Aglaonema black still outperformed Dracaena, reducing benzene levels to 0.115 ppm compared to 0.088 ppm (Fig. 1). This trend is consistent with prior literature linking broader leaf area and elevated stomatal conductance to enhanced VOC uptake⁹.

To characterize removal kinetics, a pseudo-first-order model was applied (Fig. 2). The derived rate constant (k) for Aglaonema black was 0.231 h⁻¹, with a coefficient of determination (R²) of 0.967—indicating excellent model conformity. For Dracaena deremensis, the corresponding k value was 0.184 h⁻¹, with a lower R² of 0.891. This suggests possible deviation from pure first-order behavior, potentially requiring alternative kinetic modeling approaches such as zero-order or Michaelis–Menten models for more accurate description (Fig. 2).

Fig. 2.

Trend of benzene absorption over time by aglaonema black and dracaena deremensis under different temperature conditions.

Influence of environmental conditions

This study advances prior work by quantitatively evaluating how temperature and relative humidity—two critical yet underexplored environmental factors—influence benzene uptake by indoor plants. Unlike earlier studies that broadly assessed total VOC removal, our results highlight species-specific physiological responses governing pollutant assimilation. Notably, RH and temperature exerted statistically significant and divergent effects across species (Fig. 3), reflecting a complex interplay between environmental drivers and plant function.Dracaena deremensis exhibited enhanced benzene removal at elevated humidity levels (50%), likely due to increased stomatal aperture and transpiration-driven gas exchange. In contrast, Aglaonema black performed significantly better under lower humidity conditions (~ 35%), suggesting tighter stomatal control that sustains uptake efficiency while minimizing water loss. Elevated relative humidity promotes guard cell turgor and stomatal opening, facilitating higher transpiration rates and VOC flux across the leaf surface.

Fig. 3.

Effect of temperature and humidity on benzene absorption by indoor plants.

Temperature also influenced performance: Aglaonema black showed temperature-sensitive uptake patterns (p = 0.025), whereas D. deremensis demonstrated more thermally stable behavior (p = 0.096). At 20°C, both species exhibited improved benzene removal compared to 30°C trials—likely due to reduced compound volatilization, enhanced solubility, and more effective stomatal regulation under cooler conditions. Additionally, lower temperatures may increase benzene solubility and limit leaf-level volatilization, while moderate warmth can activate enzymatic detoxification pathways—such as monooxygenases and peroxidases—thus contributing to active uptake mechanisms.These trends are consistent with prior studies showing humidity- and temperature-dependent VOC uptake in plant-based remediation systems^20,21. Aglaonema appears well-suited to arid indoor environments; previous work demonstrated its effectiveness in removing formaldehyde and toluene under similar conditions²². A mechanistic summary of these responses is presented in Table 2, outlining how environmental parameters shape phytoremediation efficiency in each species.

Table 2.

Hypothetical comparative removal efficiencies.

Species	Humidity (%)	Temperature (°C)	VOC Removal Efficiency (%)	Observed Mechanistic Response
Dracaena deremensis	50	25	High	Increased stomatal conductance; high transpiration rate
Dracaena deremensis	35	20	Moderate	Reduced stomatal aperture; decreased VOC flux
Aglaonema ‘Black’	35	20	High	Optimized stomatal responsiveness; reduced cuticular resistance
Aglaonema ‘Black’	50	25	Lower	Potential stomatal closure under excessive vapor pressure

Kinetic modeling and statistical validation

The first-order kinetic model provided a robust fit across species, with R² values ranging from 0.91 to 0.99. Table 1 summarizes the estimated rate constants and corresponding half-lives. For example, Aglaonema black exhibited a half-life of approximately 3.0 h, while Dracaena deremensis showed a significantly longer half-life of ~ 8.0 h, confirming interspecies variability in uptake kinetics.

Table 1.

Kinetic parameters (rate constant, coefficient of determination, and half-life) for benzene removal by Aglaonema Black and Dracaena deremensis under controlled experimental conditions.

Plant species	Rate constant (k) (h−1)	Coefficient of determination (R2)	Half-life (t1/2) (hours)
Aglaonema Black	0.231	0.967	3.0
Dracaena deremensis	0.184	0.891	8.0

These differences were statistically validated using 95% confidence intervals for k, which did not overlap between top and bottom performers—confirming that species identity significantly influences not only the extent but also the rate of benzene removal. Furthermore, residual analysis and lack-of-fit testing (p > 0.05) confirmed that the pseudo-first-order model adequately captured the temporal dynamics of benzene depletion.

Physiological mechanisms underpinning VOC uptake

The phytoremediation performance differences between Aglaonema ‘Black’ and Dracaena deremensis are rooted in species-specific leaf anatomy, stomatal behavior, and physiological resilience. Aglaonema maintained higher chlorophyll levels and peroxidase activity (~ 70% increase vs. ~ 30% in Dracaena) under benzene exposure, enabling more effective VOC uptake in low-humidity conditions through sustained stomatal function and gas exchange^14,17,23.

Stomatal conductance and transpiration are the main mechanisms for benzene uptake, but continued removal under low transpiration (e.g., nighttime or high humidity) suggests involvement of passive cuticular diffusion and rhizospheric microbial metabolism^24,25. In contrast to Aglaonema, Dracaena exhibited marked stomatal closure under dry conditions, reducing uptake.

Kinetic modeling further validated these patterns: Aglaonema showed a higher benzene removal rate constant (k = 0.231 h⁻¹, R² = 0.967) compared to Dracaena (k = 0.184 h⁻¹, R² = 0.891), indicating faster and more consistent VOC detoxification^17,26.

Environmental factors, particularly humidity and temperature, modulated removal efficiencies. As shown in Table 2, Aglaonema performed best under cooler, drier conditions (35% RH, 20°C), while Dracaena showed improved performance at 50% RH and 25°C. High RH typically promotes stomatal aperture, but excessive vapor pressure may induce partial closure in Aglaonema²⁷. Similarly, moderate temperatures enhance VOC solubility and leaf retention, favoring uptake²⁸.

Overall, these findings emphasize the need for species-environment matching in phytoremediation applications. Future work should validate these mechanisms in real-world indoor settings with dynamic airflows, mixed VOC profiles, and potential microbial contributions^25,29.

Statistical and mechanistic interpretation

A three-way ANOVA revealed significant main effects of species, temperature, and relative humidity (RH) on benzene removal efficiency (p < 0.05). Interaction terms (species × humidity: p = 0.017; species × temperature: p = 0.025) indicated that environmental influence on phytoremediation is species-dependent and non-additive. Post hoc Tukey’s HSD test showed that Aglaonema ‘Black’ performed significantly better at 35% RH (p = 0.031) and at 20°C (p = 0.028), while Dracaena deremensis exhibited non-significant trends toward higher efficiency at 50% RH (p = 0.096) and limited temperature sensitivity (p = 0.084).

Light intensity (1000 ± 50 lx) had no statistically significant effect on benzene uptake in either species (p > 0.05), aligning with literature that suggests moderate light levels do not limit VOC uptake in shade-tolerant species like Aglaonema and Dracaena ^27,30.

These statistical patterns reflect distinct physiological adaptations. Aglaonema's superior performance in low-humidity conditions is linked to sustained stomatal function and higher gas exchange capacity, while Dracaena is better adapted to consistently humid environments. These findings support earlier work on species-specific variation in foliar traits that influence VOC removal, such as stomatal density, cuticle permeability, and transpiration regulation^17,29.

As illustrated in Fig. 4, the combined effects of humidity, temperature, and light generated species-specific uptake profiles, reinforcing a multiphasic model of phytoremediation. While stomatal conductance is the primary driver of uptake, passive diffusion across the cuticle and rhizospheric microbial degradation become relevant under low transpiration conditions, such as nighttime or high RH ^23,24,31.

Fig. 4.

Comparative effects of temperature, humidity, and light on benzene uptake in Aglaonema black and Dracaena deremensis. The red dashed line denotes statistical significance (p = 0.05).

These mechanistic insights have direct practical implications. Aglaonema ‘Black’ is more suitable for variable or dry indoor environments, whereas Dracaena may be preferable for humid spaces. Strategic placement near emission sources—such as printers or synthetic furnishings—can enhance remediation outcomes²⁸. While the removal rates of individual plants are modest, cumulative effects in closed environments can be substantial, particularly under optimized humidity and temperature conditions ^32,33. See Table 2 for comparative performance.

Despite strong statistical signals, it is important to note that these results derive from controlled chamber experiments with limited replication (n = 3). Thus, generalizing the findings to dynamic real-world indoor environments—where ventilation, VOC mixtures, and human activity fluctuate—should be done with caution³².

Future studies should explore long-term phytoremediation performance in inhabited settings, particularly under mixed pollutant loads and variable ventilation. The integration of rhizospheric microbial communities has shown promise in enhancing VOC breakdown through co-metabolic and symbiotic pathways^23,26,28. Moreover, hybrid systems that combine plant-based removal with complementary technologies—such as photocatalytic filters or activated carbon—may offer enhanced and scalable indoor air purification strategies^25,33.

Predictive modeling of VOC uptake

To better understand and forecast phytoremediation behavior under varying environmental conditions, a first-order kinetic model was employed to quantify benzene removal rates for each species. This model assumes steady-state conditions and constant reaction rates, providing a simplified yet useful approximation for controlled experimental environments.

However, the use of a steady-state model introduces inherent limitations. Indoor environments are rarely static; fluctuations in temperature, humidity, and pollutant loads can cause dynamic shifts in uptake kinetics. Future studies should explore the use of more adaptive modeling frameworks—such as nonlinear regression, compartmental models, or time-series approaches—to better capture real-world variability.

Moreover, emerging studies have demonstrated the potential of data-driven modeling techniques, particularly machine learning algorithms (e.g., Random Forest, Support Vector Machines, and Artificial Neural Networks), to predict VOC uptake across diverse species and conditions^34,35.These tools can integrate multiple physiological, environmental, and temporal variables, offering superior predictive power in complex indoor ecosystems.

Ultimately, hybrid modeling frameworks that combine mechanistic insights with data-driven adaptability may offer the most robust and generalizable approach for future phytoremediation planning in smart building systems.

Predictive models: enhancement and validation

Model formulation and theoretical basis

To systematically quantify the synergistic influence of key environmental parameters on benzene removal via phytoremediation, a predictive model was constructed integrating ambient temperature (T), relative humidity (H), and initial benzene concentration (C). The mathematical representation is as follows:

2

where: E = Benzene removal efficiency (ppm/h), C = Benzene concentration (ppm), T = Temperature (°C), H = Humidity (%), α, β, γ = Experimentally derived coefficients representing the influence of each factor on phytoremediation performance.

This formulation is consistent with recent computational ecology and machine learning models, which suggest that VOC uptake rates are highly nonlinear and modulated by environmental volatility²⁴. Specifically, the inverse relationship with pollutant concentration reflects saturation kinetics at the leaf interface, while the multiplicative role of temperature and humidity captures their influence on stomatal conductance and VOC diffusion gradients.

Model utility and limitations

The model provides a theoretically grounded yet operationally accessible tool for estimating phytoremediation performance across variable indoor climates. Its simplicity facilitates real-time application in building management systems and integration with sensor-based control frameworks. However, this generalizability comes with caveats.

Importantly, the model assumes steady-state environmental conditions and mono-pollutant exposure, which diverge from real-world indoor ecosystems. Indoor air is dynamic, typically characterized by mixed VOC profiles, intermittent emissions, and fluctuating ventilation rates. Moreover, plant responses to environmental drivers are not strictly linear factors such as stomatal closure thresholds, vapor pressure deficits, and circadian stomatal regulation introduce significant physiological complexity³⁶.

Validation and future directions

While initial calibrations under controlled experimental conditions yield promising predictive accuracy, validation in situ remains imperative. Longitudinal testing across diverse architectural contexts—accounting for pollutant mixture effects, occupancy cycles, and HVAC influences—will be essential to refine model coefficients and ensure robust applicability.

Future work should explore coupling this model with machine learning algorithms (e.g., random forest regression, gradient boosting) to accommodate higher-order nonlinearities and potential interaction terms. Additionally, incorporating plant physiological variables—such as leaf area index, transpiration flux, and metabolic enzyme activity—may improve mechanistic accuracy.

Ultimately, the integration of predictive phytoremediation models into smart building ecosystems could enable adaptive air quality management, bridging ecological functionality with digital infrastructure in service of sustainable indoor environments.

Optimizing Benzene Removal via Phytoremediation: Experimental Observations.

Controlled environmental assays confirmed that benzene phytoremediation efficiency is both species-specific and environmentally modulated, underscoring the need for precision-based plant selection in indoor air quality interventions.

Aglaonema commutatum demonstrated peak removal efficacy under elevated temperatures (~ 30 °C) and low benzene concentrations. This trend may be attributable to temperature-enhanced enzymatic degradation, consistent with thermally activated VOC catabolic pathways reported in prior enzymological studies²¹. The observed positive correlation between uptake rate and thermal conditions reinforces the hypothesis that phytoremediation is not solely reliant on passive diffusion, but is significantly modulated by active metabolic processes, particularly those involving oxygenases and peroxidases³⁷.

Conversely, Dracaena deremensis exhibited higher benzene absorption under increased relative humidity (~ 50%), a pattern that remained consistent across replicates. This behavior is consistent with elevated stomatal conductance facilitating gaseous exchange, a mechanism extensively documented in plant-based toluene remediation models^7,9. These findings substantiate the central role of transpirational dynamics in VOC flux regulation and highlight humidity as a critical variable in optimizing stomatal-mediated uptake.

Collectively, these results validate the need for Eco physiologically informed species selection when deploying phytoremediation systems. Rather than assuming uniform functionality across plant taxa, alignment between species-specific physiological traits—such as stomatal behavior, leaf hydrophobicity, and enzymatic potential—and indoor microclimatic parameters is essential for maximizing VOC mitigation outcomes.

Sensitivity analysis: influence of environmental parameters on phytoremediation performance

To evaluate the relative contribution of key environmental drivers to benzene removal efficiency in phytoremediation systems, a structured sensitivity analysis was conducted. The results revealed non-linear and species-specific response patterns, highlighting the importance of microclimatic optimization in plant-based indoor air remediation strategies.

Temperature (T)

A 10% increase in ambient temperature yielded an approximate 20% enhancement in benzene removal efficiency by Aglaonema commutatum. This disproportionate gain aligns with thermally induced acceleration of enzymatic degradation pathways, particularly those involving peroxidases and cytochrome P450 monooxygenases^38,39. These findings support the hypothesis that temperature not only modulates passive gas exchange but actively stimulates intracellular VOC metabolism—suggesting a catalytic threshold behavior in phytoremediation kinetics.

Relative humidity (H)

In Dracaena deremensis, a 10% rise in relative humidity led to a 15% increase in benzene uptake. This enhancement is likely attributable to elevated stomatal aperture and transpiration flux, both of which are known to increase under humid conditions¹⁸. (Additionally, high humidity improves the aqueous solubility of VOCs at the leaf-air interface, thereby facilitating diffusion through the stomatal pathway.

Pollutant concentration (C)

A logarithmic decline in removal efficiency was observed at higher benzene concentrations, indicative of enzymatic or physiological saturation. Such behavior suggests that beyond a critical exposure threshold, VOC assimilation becomes constrained by either limited enzymatic turnover or reduced stomatal conductance due to pollutant-induced stress or feedback inhibition. This finding is consistent with established models of VOC uptake, which predict sublinear or plateau responses under elevated pollutant loads⁴⁰.

Interpretation and practical implications

The observed differential sensitivity of species to temperature and humidity underscores the need for context-specific deployment of phytoremediation strategies. In practice, this translates to:

• Prioritizing Aglaonema in warmer indoor environments with moderate pollutant levels, where thermal stimulation of enzymatic activity can be leveraged.

• Utilizing Dracaena in humidified settings such as bathrooms, spas, or tropical climates, where stomatal-driven gas exchange is maximized.

Moreover, the nonlinear response to pollutant concentration reinforces the limitations of phytoremediation under high-load scenarios. Passive plant-based systems may be insufficient alone and should be integrated with supplemental technologies (e.g., adsorption filters or photocatalytic surfaces) to achieve regulatory air quality thresholds.

Limitations

A key limitation of this study is the small sample size (n = 3), which, while consistent with prior controlled-environment phytoremediation research, may restrict the generalizability of the findings. Future studies should include larger replicates to increase statistical robustness and validate these results under more variable conditions.

Conclusion

The findings of this study confirm that Aglaonema black and Dracaena deremensis are capable of significantly reducing indoor benzene concentrations. Their removal efficiencies were strongly modulated by environmental conditions: Aglaonema black performed optimally at lower temperatures and moderate humidity, while Dracaena deremensis exhibited enhanced benzene uptake under higher humidity levels.

These results underscore the critical importance of species-specific selection tailored to prevailing environmental parameters to optimize phytoremediation performance. Fine-tuning biotic (e.g., plant traits) and abiotic (e.g., temperature, humidity) factors can substantially enhance the efficacy of indoor air purification.

While the present study was conducted under controlled laboratory conditions, future field-based investigations are essential to validate these outcomes in dynamic real-world environments, especially those characterized by mixed VOCs, fluctuating ventilation, and human occupancy patterns.

In summary, this research provides a scientifically grounded framework for integrating ornamental plants into next-generation, low-energy indoor air purification systems—particularly within smart buildings and urban environmental management strategies.

Author contributions

Farzaneh Borzabadi Farahani: Conceptualization, Methodology, Investigation, Formal analysis, Writing—original draft. Jamshid Rahimi, Sanaz Khoramipour, Emad Dehghanifard Investigation, Methodology. Mahmood Alimohammadi: Investigation, Methodology, Writing—review & editing, Supervision. All authors read and approved the final manuscript.

Funding

This research was funded by the Department of Environmental Engineering, Islamic Azad University, Tehran West Branch.

Data availability

The datasets generated and analyzed during the current study were available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors of this article declare that they have no conflict of interest.