Search Results (45)

A VOC-contaminated shallow aquifer in an industrial site was investigated to evaluate its potential for natural attenuation. The shallow groundwater aquifer beneath the industrial site has been contaminated by dissolved volatile organic compounds (VOCs) such as trichloroethylene (TCE), cis-1,2-dichloroethylene (cis-DCE), and vinyl chloride (VC) for more than three decades. Monitoring and investigation were implemented during 2011–2024, aiming to propose future groundwater aquifer management strategies. This study included groundwater borehole investigation, well installation monitoring, hydraulic head measurements, slug tests, groundwater samplings, and microbial analyses. Microbial investigations identified the predominant group of microorganisms of Proteobacteria, indicating biodegradation potential, as demonstrated by the presence of cis-DCE and VC. BIOSCREEN was used to evaluate the process of natural attenuation, incorporating site-specific parameters. A two-layer groundwater flow model was developed using MODFLOW with hydraulic conductivities obtained from slug tests. The site has an average hydraulic head of 259.6 m amsl with a hydraulic gradient of 0.026, resulting in an average groundwater flow velocity of 11 m/y. Hydraulic conductivities were estimated during model calibration using the PEST pilot point technique. A reactive transport model, RT3D, was used to simulate dissolved TCE transport over 30 years, which can undergo sorption as well as biodegradation. Model calibration demonstrated a satisfactory fit between observed and simulated groundwater heads with a root mean square error of 0.08 m and a correlation coefficient (r) between measured and simulated heads of 0.81, confirming the validity of the hydraulic conductivity distribution. The TCE plume continuously degraded and gradually migrated southward, generating a cis-DCE plume. The concentrations in both plumes decreased toward the end of the simulation period at Source 1 (located upstream), while BIOSCREEN results confirmed ongoing natural attenuation primarily by biodegradation. The integrated MODFLOW-RT3D-BIOSCREEN approach effectively evaluated VOC attenuation and plume migration. However, future remediation strategies should consider enhanced bioremediation to accelerate contaminant degradation at Source 2 and ensure long-term groundwater quality. Full article

Groundwater remains a critical water source for urban communities, particularly in rapidly urbanizing countries such as the Philippines. However, intensifying anthropogenic pressures have contributed to widespread contamination from heavy metals, nutrients, pathogens, volatile organic compounds (VOCs), and emerging pollutants, including pharmaceuticals and personal care products (PPCPs). This review synthesizes findings from 130 peer-reviewed studies on groundwater monitoring and remediation, emphasizing technological advancements and their application in urban environments. The literature is categorized into five thematic areas: monitoring technologies, contaminant profiles, remediation strategies, Philippine-specific case studies, and alignment with global frameworks. Recent innovations—such as Internet of Things (IoT)-enabled systems, remote sensing, biosensors, and artificial intelligence/machine-learning (AI/ML) models—show strong potential for real-time and predictive monitoring. Despite these advancements, technology adoption in the Philippines remains limited due to regulatory, technical, and infrastructural constraints. This review identifies key research and implementation gaps, particularly in the monitoring of emerging contaminants and the integration of data into policy-making and urban planning. To address these challenges, a conceptual framework is proposed to support more sustainable, technology-driven, and context-sensitive groundwater management in heavily urbanized areas. Full article

Aromatic volatile organic compounds (VOCs) pose significant environmental and public health risks due to their toxicity, carcinogenicity, and role as precursors of hazardous secondary pollutants. Zeolite-based metal catalysts, with their well-defined microporous structures, tunable acidity, and high thermal stability, have shown promise in the catalytic oxidation of aromatic VOCs. However, the influence of the zeolite microenvironment on supported metal active sites remains insufficiently understood, limiting the rational design of advanced catalysts. This review highlights how microenvironmental parameters—including pore architecture, acid site distribution, framework composition, and surface/interface engineering—can be modulated to enhance adsorption, oxygen activation, and metal–support interactions. Advances in hierarchical porosity, heteroatom substitution, and surface hydrophobicity are discussed. This review provides a framework for the development of next-generation zeolite-based catalysts and offers strategic guidance for advancing microenvironment-controlled catalysis in sustainable environmental remediation. Full article

This study explored how pore size engineering in Nb-Mn/MCM-41 catalysts affects plasma-catalytic toluene oxidation. Adjusting the pore diameter (2.49–3.98 nm) modulated metal-support interactions and oxygen dynamics, with pore expansion to 3.73 nm (M3) optimizing the Mn⁴⁺/(Mn²⁺ + Mn³⁺) ratio (XPS: 36.8%), the amount of lattice oxygen species (O₂-TPD: 0.222 mmol/g), and crystallite size control (1.5 ± 0.2 nm, TEM). Smaller pores (M1: 2.49 nm) enhanced toluene adsorption but limited active site accessibility, while oversized pores (M4: 3.98 nm) reduced oxygen storage capacity (0.600→0.412 mmol/g). The Nb-Mn/M3 catalyst achieved superior performance with 96.8% toluene conversion, 55.0% CO₂ selectivity, and 85.4% carbon balance, while minimizing organic byproducts (GC-MS). Mechanistic studies revealed pore-mediated oxygen storage-transport cycles as critical for decoupling adsorption and oxidation steps. This study reveals fundamental mechanisms linking pore architecture to plasma-catalytic synergy in toluene oxidation, offering critical insights for the systematic design of energy-efficient, plasma-catalytic systems targeting industrial VOCs remediation. Full article

Soil organic pollution poses a significant threat to agricultural safety in China, underscoring the critical importance of developing efficient remediation technologies for soil environmental protection. Steam injection, a promising method for removing organic pollutants from soil, has yet to be thoroughly investigated in terms of its energy efficiency. A novel steam injection system with horizontal wells is proposed to remediate soil xylene pollution, and a corresponding numerical model is established and solved through TOUGH2-T2VOC codes. The energy efficiency characteristics and main influencing factors of the system are analyzed. The results demonstrate that steam injection is an effective method to remediate xylene pollution. It is evaluated that during the first 1.5 years of the 5-year operation period, production xylene saturation gradually decreases from 0.3 to 0.05, and the production xylene mass flow rate gradually decreases from 0.179 kg/s to 2.448 × 10⁻⁴ kg/s. Pump power consumption gradually increases from 17.23 kW to 30.67 kW, while energy efficiency gradually decreases from 7.73 × 10⁻⁴ kg/kJ to 1.00 × 10⁻⁶ kg/kJ. Sensitivity analyses indicate that the main factors affecting the xylene mass flow rate are formation permeability, production pressure and the initial xylene saturation, and the main factors affecting energy efficiency are the steam injection flow rate, formation permeability, production pressure and initial xylene saturation. This has significant practical significance for the optimal design of the steam injection remediation scheme for soil organic pollution. Full article

With industrialization and widespread chemical use, soil organic pollutants have become a major environmental issue. Forest ecosystems, among the most important on Earth, have unique potential for controlling and remediating soil pollution. This article explores the mechanisms of microbial community degradation of organic pollutants, their adaptability across forest ecological conditions, and the effects of environmental factors on degradation efficiency. For example, acidic pH (pH < 5.5) favors PAH degradation, near-neutral pH (6.0–7.5) enhances pharmaceutical and PPCP degradation, and alkaline conditions (pH > 7.5) facilitate petroleum hydrocarbon, VOC, and PPCP breakdown. Optimal microbial degradation occurs with humidity levels between 60% and 80%, and SOM content of 2–5%. This review analyzes advancements in microbial degradation technologies for forest ecosystem soil pollution treatment, including genetic engineering, composting, bioaugmentation, and bio-stimulation techniques, and their integration with phytoremediation. The review also addresses the challenges of real-world implementation, such as maintaining microbial diversity, managing pollutant complexity, adapting to environmental changes, and highlighting future research opportunities. The next decade will focus on synthetic biology, omics technologies, microbial-electrochemical systems, community dynamics, eco-engineering, and plant-microbe synergy to develop efficient, sustainable bioremediation strategies. Full article

Since people spend most of their time in indoor environments, they are continuously exposed to various contaminants that threaten human health. The air quality in these settings is therefore a crucial factor in maintaining health safety. In order to reduce the concentration of indoor air pollutants and improve air quality, photocatalytic oxidation has drawn the attention of researchers. This study aims to provide a comprehensive view of the nanomaterials used in the photocatalytic oxidation of the most common pollutants in indoor environments. The effects of various parameters like humidity, airflow, deposition time, and light intensity were also evaluated, as they can significantly influence photocatalytic reactions. The most common nanomaterials used in photocatalysis are TiO₂-based and, in this study, they were classified and examined based on their morphology. TiO₂ doping with metals and non-metals has demonstrated an enhancement of its adsorption properties and photocatalytic efficiency for the removal of several pollutants. The role of carbon-based nanomaterials in photocatalysis was also evaluated due to their adsorption capabilities towards various pollutants. In addition, other less common photocatalysts such as ZnO, MnO₂, WO₃, CeO₂, and CdS also exhibited high photocatalytic activity for pollutant degradation. Applications of these photocatalysts in air purifiers, paints, and building materials e.g., concrete, glass, and wallpapers, lead to efficient reduction of pollutants in indoor settings. Full article

This study explores the synergistic interactions between photocatalysis, ozone treatment, and metal catalysts in the decomposition of acetaldehyde, a representative volatile organic compound (VOC). The study addresses the growing need for efficient air purification technologies by integrating advanced oxidation processes. Metal catalysts, particularly manganese oxide-based materials, were combined with photocatalysis and ozonation to investigate their impact on acetaldehyde removal efficiency. Experimental results revealed that the treatment integrating these methods significantly outperformed conventional single-process treatments. Metal catalysts facilitated the initial oxidation of acetaldehyde, while photocatalysis accelerated subsequent stages, including the mineralisation of intermediates. Ozone contributed additional reactive oxidative species, further enhancing decomposition rates. These findings provide valuable insights into the design of efficient VOC removal systems, demonstrating that integrating metal catalysts with photocatalytic and ozonation processes offers a promising strategy for improving air purification technologies. This approach has potential applications in environmental remediation and indoor air quality management. Full article

Biomass waste, generated globally in vast quantities, represents an underutilized yet highly valuable resource for advanced material production. This study highlights a novel valorization pathway for waste tangerine peels, sourced from Jeju Island, South Korea, by converting them into high-performance activated carbon (T-AC) with exceptional pore characteristics, specifically designed for volatile organic compound (VOC) removal. Utilizing a unique combination of hydrothermal carbonization (HTC) and dry carbonization (DC) processes, the structural properties of the biomass were optimized, significantly enhancing the fixed carbon content. Subsequent chemical activation with an alkaline agent yielded T-AC with an outstanding specific surface area (1530–3375 m²/g) and total pore volume (0.73–2.00 cm³/g), with a tailored pore distribution favoring the sub-mesopore range (2.0–4.0 nm). The T-AC demonstrated remarkable performance in removing methylene chloride (MC), a hazardous VOC, with methylene chloride activity (MA) increasing from 44.7% to 76.3% as the activation agent ratio increased, while methylene chloride working capacity (MWC) improved significantly from 17.1% to 55.9%. These results underscore the transformative potential of tangerine peel-derived AC as a sustainable solution for VOC remediation, combining environmental waste management with advanced adsorption technology. The findings not only advance the field of biomass utilization but also offer a scalable approach for tackling pressing environmental and industrial challenges. Full article

Air pollution has become one of the biggest problems throughout the world. Smog has a severe effect on the pulmonary and circulatory systems, which causes a significant number of deaths globally. Therefore, the remediation of air pollutants to maintain ecosystem processes and functions and to improve human health is a crucial problem confronting mankind today. This review aims to discuss the health effects of smog on humans. This review will also focus on the bioremediation of air pollution (smog) using bacteria, fungi, phytoremediation, nanotechnology, and phylloremediation (using plants and microbes). Phylloremediation is the most effective technology for removing air pollution naturally. The future perspective presents a great need to produce an ecosystem where microbes, plants, and nanoparticles synergistically control smog. In addition, further advancements would be needed to modify the genetic makeup of microbes and plants. Biotechnological approaches like CRISPR-Cas9 can be applied to the editing and cutting of specific genes responsible for the bioremediation of VOCs, NOx, SOx, and harmful hydrocarbons. The extracted genes can then be expressed in biologically modified microorganisms and plants for the enhanced bioremediation of smog. Full article

Volatile organic compounds (VOCs), particularly aromatic hydrocarbons, pose significant environmental risks due to their toxicity and role in the formation of secondary pollutants. This study explores the potential of catalytic pyrolysis as an innovative strategy for the effective remediation and conversion of aromatic hydrocarbon pollutants. The research investigates the high-efficiency removal and resource recovery of the VOC toluene using a Ni/Al₂O₃ catalyst. The Ni/Al₂O₃ catalyst was synthesized using the impregnation method and thoroughly characterized. Various analytical techniques, including scanning electron microscopy, X-ray diffraction, and N₂ adsorption–desorption isotherms, were employed to characterize the Al₂O₃ support, NiO/Al₂O₃ precursor, Ni/Al₂O₃ catalyst, and the resulting solid carbon. Results indicate that Ni predominantly occupies the pores of γ-Al₂O₃, forming nano/microparticles and creating interstitial pores through aggregation. The catalyst demonstrated high activity in the thermochemical decomposition of toluene into solid carbon materials and CO_x-Free hydrogen, effectively addressing toluene pollution while recovering valuable resources. Optimal conditions were identified, revealing that a moderate temperature of 700 °C is most favorable for the catalytic process. Under optimized conditions, the Ni/Al₂O₃ catalyst removed 1328 mg/g of toluene, generated 915 mg/g of carbon material, and produced 1234 mL/g of hydrogen. The prepared carbon material, characterized by its mesoporous structure and high specific surface area graphite nanofibers, holds potential application value in adsorption, catalysis, and energy storage. This study offers a promising approach for the purification and resource recovery of aromatic volatile organic compounds, contributing to the goals of a circular economy and green chemistry. Full article

In this study, a novel perovskite solar cell (PSC) architecture is presented that utilizes an HTL-free configuration with formamide tin iodide (FASnI₃) as the active layer and fullerene (C60) as the electron transport layer (ETL), which represents a pioneering approach within the field. The elimination of hole transport layers (HTLs) reduces complexity and cost in PSC heterojunction structures, resulting in a simplified and more cost-effective PSC structure. In this context, an HTL-free tin HC(NH₂)₂SnI₃-based PSC was simulated using the solar cell capacitance simulator (SCAPS) within a one-dimensional framework. Through this approach, the device performance of this novel HTL-free FASnI₃-based PSC structure was engineered and evaluated. Key performance parameters, including the open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF), power conversion efficiency (PCE), I-V characteristics, and quantum efficiency (QE), were systematically assessed through the modulation of physical parameters across various layers of the device. A preliminary analysis indicated that the HTL-free configuration exhibited improved I-V characteristics, with a PCE increase of 1.93% over the HTL configuration due to improved electron and hole extraction characteristics, reduced current leakage at the back contact, and reduced trap-induced interfacial recombination. An additional boost to the device’s key performance parameters has been achieved through the further optimization of several physical parameters, such as active layer thickness, bulk and interface defects, ETL thickness, carrier concentration, and back-contact materials. For instance, increasing the thickness of the active layer PSC up to 1500 nm revealed enhanced PV performance parameters; however, further increases in thickness have resulted in performance saturation due to an increased rate of hole–electron recombination. Moreover, a comprehensive correlation study has been conducted to determine the optimum thickness and donor doping level for the C60-ETL layer in the range of 10–200 nm and 10¹²–10¹⁹ cm⁻³, respectively. Optimum device performance was observed at an ETL-C60 ultra-thin thickness of 10 nm and a carrier concentration of 10¹⁹ cm⁻³. To maintain improved PCEs, bulk and interface defects must be less than 10¹⁶ cm⁻³ and 10¹⁵ cm⁻³, respectively. Additional device performance improvement was achieved with a back-contact work function of 5 eV. The optimized HTL-free FASnI₃ structure demonstrated exceptional photovoltaic performance with a PCE of 19.63%, V_oc of 0.87 V, J_sc of 27.86 mA/cm², and FF of 81%. These findings highlight the potential for highly efficient photovoltaic (PV) technology solutions based on lead-free perovskite solar cell (PSC) structures that contribute to environmental remediation and cost-effectiveness. Full article

Volatile organic compounds (VOCs) are common organic pollutants that can cause adverse effects on human health. Treatment techniques, including photocatalytic oxidation, have been studied to remediate VOCs. Acetone was used as a model pollutant to investigate the photocatalytic degradation performance of electrospun photocatalytic nanofibers with synthesized flower-like titanium dioxide (F-TiO₂) and cellulose acetate (CA). The synthesized F-TiO₂ and photocatalytic nanofibers were characterized using FE-SEM, XRD, FTIR, UVVis, XPS, and a pore size and porosity analyzer. The addition of F-TiO₂ decreases the diameter of the nanofibers. The photocatalytic degradation performance test showed an enhanced acetone degradation efficiency on F-TiO₂/CA photocatalytic nanofibers (FT-CFs), with an up to 95.0% acetone degradation efficiency under optimum conditions, over P25 TiO₂/CA photocatalytic nanofibers (T-CFs). The filtration efficiency of 3.0%FT-CF reached 99.9% with a filter basis weight of 0.660 g m⁻² and face velocity of 5.0 cm⁻¹ s. The filtration and photocatalytic degradation cycle tests revealed excellent reusability, with 97% particle filtration and no sign of material deterioration. Moreover, the biodegradability tests showed that the material can biodegrade in water and in soil for 30 and 40 days, respectively. This study demonstrates that electrospun FT-CFs exhibit exceptional photocatalytic degradation of acetone, a high filtration efficiency, excellent reusability, and biodegradability, making them a promising solution for VOC remediation. Full article

Less attention was paid to the remediation of volatile organic compounds (VOCs) contaminated soil treated by thermal conduction heating (TCH) coupled with chemical oxidization. In this study, the lab-scale remediation experiments of trichloroethylene (TCE)-contaminated soil by TCH and TCH coupled with persulfate (TCH + PS) were performed to explore the influences of PS usage, temperature, reaction time, and the variation of soil properties. TCE was removed from contaminated soils using TCH with a temperature lower than boiling point, and the removal ratio of TCE reached 78.21% with a reaction time of 6h at 60 °C. In the TCH + PS treatments, the removal ratio increased to 87.60~99.50% when the PS dosage was increased from 7.0 mmol/kg to 17.5 mmol/kg at 60 °C. However, the usage efficiency of PS had no positive relationship with oxidant usage and temperature. The treatment with 14 mmol/kg PS after 3h at 50 °C had the highest PS usage ratio of 3.05. In addition, soil pH and soil organic matter (SOM) did not decrease significantly in the TCH-only treatment, while the content of SOM declined by almost 50% after the TCH + PS treatment. Overall, it was concluded that TCH + PS achieved higher removal efficiency, whereas TCH had less disturbance on soil pH and SOM. As such, the applicability of TCH-only or TCH + PS treatments is site-specific. Full article

Volatile organic compounds (VOCs) are prevalent soil contaminants. During the ex situ soil remediation process, VOCs may overflow from the soil and cause gas to diffuse into the atmosphere. Moreover, some VOCs, such as trichloromethane, are categorized by the EPA as emerging contaminants, imparting toxicity to organs, and the endocrine and immune systems, and posing a huge threat to human health and the environment. To reduce VOCs’ emissions from contaminated soil, aqueous foam suppression is a prospective method that provides a durable mass transfer barrier for VOCs, and it has been widely used in odor control. Based on an aqueous foam substrate, in order to enhance the foam’s stability and efficiency of suppression, SiO₂–TiO₂-modified nanoparticles have been used as stabilizing agents to improve the mechanical strength of liquid film. The nanoparticles are endowed with the ability to photocatalyze after the introduction of titanium dioxide. From SEM imaging, IR, and a series of morphological characterization experiments, the dispersibility of the SiO₂–TiO₂-modified nanoparticles was significantly improved under the polar solvent, which, in turn, increased the foam duration. The foam dynamic analysis experiments showed that the foam liquid half-life was increased by 4.08 h, and the volume half-life was increased by 4.44 h after adding the novel synthesized nanoparticles to the bulk foam substrate. From the foam VOC suppression test, foam with modified nanoparticles was more efficient in terms of VOCs’ suppression, in contrast with its nanoparticle-free counterparts, due to the longer retention time. Moreover, in a bench-scale experiment, the SiO₂–TiO₂ nanoparticles foam worked against dichloroethane, n–hexane, and toluene for almost 12 h, with a 90% suppression rate, under UV irradiation, which was 2~6 h longer than that of UV-free SiO₂–TiO₂ nanoparticles, the KH–570-modified nanosilica foam, and the nanoparticle-free bulk foam. XPS and XRD results indicate that in SiO₂–TiO₂ nanoparticles, the proportion of titanium valence was changed, providing more oxygen vacancies compared to raw titanium dioxides. Full article