Industrial Volatile Organic Compounds Research Articles

Performance and microbial community evolution of toluene degradation in the presence of acetone vapors using hybrid membrane-aerated biofilm reactors (HMABRs)

Biological treatment methodologies offer cost-effective and eco-friendly solutions for volatile organic compounds (VOCs) removal, but they face limitations in effectively treating hydrophobic VOCs. Herein, this study introduces the Hybrid Membrane Aerated Biofilm Reactor (HMABR) for VOC treatment. The HMABR integrates a bio-trickling filter-like spraying function with MABR technology to construct a non-submerge system. What’s more, introducing hydrophilic gases enhances the degradation of hydrophobic VOCs in pollutant biotreatment. While hydrophilic VOCs are readily degraded by microorganisms, the mechanisms of their co-degradation remain understudied. Toluene and acetone, common industrial VOCs, were examined in the HMABR system. HMABR exhibits outstanding toluene removal, reaching a maximum capacity of 142.04 gm−3h−1. The addition of acetone boosts this capacity by 70.1 gm−3h−1, altering EPS composition, and notably increasing the PN/PS ratio from 0.35 to 2.76. It can be inferred that acetone’s presence enhances biofilm EPS hydrophobicity, aiding toluene breakdown. Besides, when adding acetone, the biofilm EPS sample exhibited a more compact secondary protein structure. Analysis of the microbial community in the HMABR system identified a dominance of Pseudomonadota, with an increased abundance of Rhodanobacter, which correlated strongly with toluene degradation in the presence of acetone. Gene analysis revealed an increase in toluene degradation genes in Rhodanobacter when acetone was added. Furthermore, acetone activation was found to enhance metabolic pathways related to xylene degradation and the tricarboxylic acid (TCA) cycle, thereby improving toluene removal efficiency. These findings provide insights into co-metabolism in treating hydrophobic pollutants in HMABR and contribute to designing more effective treatment systems for VOCs.

Performance on adsorption of toluene by ionic liquid-modified AC in high-humidity exhaust gas.

Volatile organic compounds (VOCs) frequently pose a threat to the biosphere, impacting ecosystems, flora, fauna, and the surrounding environment. Industrial emissions of VOCs often include the presence of water vapor, which, in turn, diminishes the adsorption capacity and efficacy of adsorbents. This occurs due to the competitive adsorption of water vapor, which competes with target pollutants for adsorption sites on the adsorbent material. In this study, hydrophobic activated carbons (BMIMPF6-AC (L), BMIMPF6-AC (g), and BMIMPF6-AC-H) were successfully prepared using 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) to adsorb toluene under humidity environment. The adsorption performance and mechanism of the resulting ionic liquid-modified activated carbon for toluene in a high-humidity environment were evaluated to explore the potential application of ionic liquids as hydrophobic modifiers. The results indicated that BMIMPF6-AC-H exhibited superior hydrophobicity. The toluene adsorption capacity of BMIMPF6-AC-H was 1.53 times higher than that of original activated carbon, while the adsorption capacity for water vapor was only 37.30% of it at 27 °C and 77% RH. The Y-N model well-fitted the dynamic adsorption experiments. To elucidate the microscopic mechanism of hydrophobic modification, the Independent Gradient Model (IGM) method was employed to characterize the intermolecular interactions between BMIMPF6 and toluene. Overall, this study introduces a new modifier for hydrophobic modification of activated carbon, which could enhance the efficiency of activated carbon in treating industrial VOCs.

Dynamic simulation and analysis of dichloromethane-acetone, dichloromethane-trichloromethane and dichloromethane-toluene VOC mixture abatement systems under transient feed conditions

Minimisation of environmental footprint in line with sustainability goals rests at the top of the agenda of the pharmaceutical industry. Volatile Organic Compounds (VOCs), while essential to primary pharmaceutical manufacturing, are solvents whose emissions pose a risk to human health and ecosystems. Adsorption on activated carbon beds is an established technology for end of pipe emissions control, which, however, faces efficiency limitations by quick and irregular bed saturation due to complex, transient feeds. This study employs a validated nonisothermal, multicomponent adsorption model to quantitatively assess the exact effect and potential value of waste stream feed sequencing towards activated carbon bed utilisation optimisation. Our results indicate that gradual increase of dichloromethane feed concentration in combination with a low, constant inlet concentration of the strongly adsorbing component leads to the latest breakthrough onset for the dichloromethane-acetone, dichloromethane-chloroform and dichloromethane-toluene mixtures. Transient vs. constant feeds usage and their interplay clearly affects bed behaviour, paving the way to industrial VOC emission abatement scheduling and process optimisation.

Efficacious destruction of typical aromatic hydrocarbons over CoMn/Ni foam monolithic catalysts with boosted activity and water resistance

Developing cost-effective monolith catalyst with superior low-temperature activity is critical for oxidative efficacious removal of industrial volatile organic compounds (VOCs). However, the complexity of the industrial flue gas conditions demands the need for high moisture tolerance, which is challenging. Herein, CoMn–Metal Organic Framework (CoMn–MOF) was in situ grown on Ni foam (NiF) at room temperature to synthesize the cost-effective monolith catalyst. The optimized catalyst, Co1Mn1/NiF, exhibited excellent performance in toluene oxidation (T90 = 239 °C) due to the substitution of manganese into the cobalt lattice. This substitution weakened the Co–O bond strength, creating more oxygen vacancies and increasing the active oxygen species content. Additionally, experimentally and computationally evidence revealed that the mutual inhibiting effect of three typical aromatic hydrocarbons (benzene, toluene and m–xylene) over the Co1Mn1/NiF catalyst was attributed to the competitive adsorption occurring on the active site. Furthermore, the Co1Mn1/NiF catalyst also presents outstanding water resistance, particularly at a concentration of 3 vol%, where the activity is even enhanced. This was attributed to the lower water adsorption and dissociation energy derived from the interaction between the bimetals. Results demonstrate that the dissociation of water vapor enables more reactive oxygen species to participate in the reaction which reduces the formation of intermediates and facilitates the reaction. This investigation provides new insights into the preparation of oxygen vacancy–rich monolith catalysts with high water resistance for practical applications.

Novel technology for industrial VOCs exhaust treatment under dual-carbon target based on multivariate statistical analysis

Abstract Against the background of the dual-carbon target, the treatment of volatile organic compounds (VOCs) emissions in the industrial sector, especially in the chemical industry, has become an urgent environmental issue. To provide scientific and objective guidance for technology selection, this study constructs a comprehensive evaluation model based on the combination of entropy weighting method and hierarchical analysis method for the complete progress of VOCs treatment technologies, taking into account the four main factors of environment, economy, management and technology and the thirteen secondary factors under them. The model provides in-depth quantitative analysis and evaluation of ten common VOCs end-of-pipe treatment technologies. The evaluation results show that thermal combustion, catalytic combustion, adsorption-concentration-combustion, and photocatalysis exhibit high comprehensive efficacy in VOCs emission treatment, with relative weight values of 0.1273, 0.1252, 0.1214, and 0.1184, respectively. These findings provide essential references and guidance for chemical companies in selecting suitable VOCs treatment technologies, which help to realize the win-win situation of environmental protection and economic development. This study fills the gap in evaluating VOCs emission management technologies and provides a practical decision-making tool for relevant decision makers.

Spatiotemporal distribution, source apportionment and health risk assessment of atmospheric volatile organic compounds using passive air samplers in a typical coastal area, China

To fully understand source characteristics and human health effects of atmospheric volatile organic compounds (VOCs), it is of great importance to implement long-term measurements, precise source apportionment and simulation. In this study, a 12-month measurement of VOCs was conducted in a coastal area in East China by a novel passive air sampler (PAS). A total of 28 VOC species, mainly in groups of aromatics and halohydrocarbons were observed. The monthly average concentrations of TVOC were as follows: industrial sites (154.10–727.19 μg m−3) > business sites (65.83–86.96 μg m−3) > residential sites (59.63–60.05 μg m−3) > background site (57.62 μg m−3). Their seasonal variation characteristics were: winter > spring > autumn > summer, which was more apparent at industrial sites due to human activities. Six VOC sources including industrial processes, organic solvents, dyeing, plastic synthesis, traffic emissions, and pesticides identified by the positive matrix factorization model compared favorably with the local emissions at industrial sites. Bromoform, hexachloro-1,3-butadiene, C1–C3 halogenated alkanes and benzene homologs could be the important indicators of industrial VOC emissions. The halohydrocarbons and aromatics were the major contributors to the ozone formation potential (OFP) and secondary organic aerosol potential (SOAP) in industrial areas, respectively. Both of OFP and SOAP have their maximum values in winter due to high VOC concentrations. Health risk assessment indicated that a high probability of non-carcinogenic risk (HI > 1) was in the region at 10 m height and 50m radius, and minor carcinogenic risk (CR > 10−6) was in the region at 70 m height and 1000 m radius. Among all the compounds, 1,2-Dibromo-3-chloropropane was the largest contributor with the individual HI value (17.99) and carcinogenic risk (5.34 × 10−3) at the peak. In this study, the PAS as a sampling tool was proven to be reliable and efficient for long-term measurements in coastal areas. It is worth to have further studies to promote passive sampling as an alternative to VOCs monitoring methods.

Impact of plasma polymerized Iodine-Doped thiophene films for enhanced sensing response towards industrial VOCs

Volatile organic compounds (VOCs) are majorly used in the manufacturing industry and are hazardous to the sustainability of the environment. Polymeric sensors, rather than more traditional metal oxide sensors, are currently taking the lead attention in the greater part of VOC sensing investigations. In polymeric sensors, plasma polymerized thiophene (PPTh) films are being investigated because of their unique properties, wasteless fabrication, and feasibility for commercial mass manufacturing. In the present study, we fabricated PPTh films powered by a 13.6 MHz RF generator with a vacuum level of 10-3 Torr in a home-built plasma system. The gas sensor investigation of PPTh and iodine-doped PPTh samples with various VOCs, such as ethanol, methanol, acetone, benzene, toluene, and dichloromethane, was carried out systematically. The iodine-doped PPTh 10–20 films (48 hr) showed the highest sensitivity for ethanol (∼180) and methanol (∼120) as compared to PPTh for ethanol (∼110) at 1000 ppm gas concentration. A sensitivity degradation study over 60 days revealed the long-term stability of the films in the air. The polar hopping mechanism and decreased charge transport centers after reaction with the hydroxyl group are responsible for resulted sensitivity of iodine-doped PPTh films towards alcohols.

Characterizing VOCs emissions of five packaging and printing enterprises in China and the emission reduction potential of this industry

The packaging and printing industry has become an important source of industrial volatile organic compounds (VOCs) emissions in China, due to the abundant consumption of organic materials. Effective control measures must be developed which rely on a comprehensive understanding of both current emission characteristics and future emission projections. However, representative VOCs source profiles and updated EFs of packaging and printing industry in China are still lacking. In order to fully explore the VOCs emissions characteristics of packaging and printing industry, field measurements including 17 processes in five packaging and printing factories were conducted in this study. The emission factors (EFs), VOCs source profiles, ozone formation potential (OFP) and secondary organic aerosols potential (SOAP) of 110 VOCs species were acquired. Speciated VOCs emission inventory of packaging and printing industry was compiled based on the activity data in 2020. The future reduction perspectives of packaging and printing industry in China were projected. The VOCs EFs of different materials were estimated, including solvent-based ink (287 g/kg), water-based ink (117 g/kg), soybean oil ink (44 g/kg), UV curing ink (22 g/kg), solvent-based adhesive (420 g/kg), and water-based adhesive (139 g/kg). The VOCs EFs of products were 35.58 kg/t for plastic wrapper, 7.28 g/m2 for soft package plastic, 0.083 g/piece for carton, 0.54 g/piece for tin case, and 0.14 g/piece for aluminum can. The total VOCs emissions in Chinese packaging and printing industry was estimated to 634.32 Gg in 2020. Guangdong, Zhejiang, Jiangsu, Fujian, Shandong, and Sichuan contributed 73% to total VOCs emissions. Printing workshop was the main contributor to both primary emission and secondary pollutant generation. OVOCs was the most abundant specie in three sub-industries. The key VOCs species in PF were ethylacetate, ethanol, 2-pentanone, methyl ethyl ketone, and i-propanol. I-propanol, ethanol, m-tolualdehyde, and dichloromethane were dominated in PP. Ethanol, m/p-xylene, i-propanol, o-xylene, and acetaldehyde were the key species in MC. The key VOCs species to OFP and SOAP were ethanol, methyl ethyl ketone, 2-pentanone, ethyl methacrylate, acetaldehyde, toluene, and xylene, which should be prioritized. The VOCs emissions would be reduced by 46.5% in 2025 and 66.4% in 2030 with stringent control measures. Increasing the usage proportion of low-VOCs-contained raw material and improving treatment efficiency are the key technologies to reduce the VOCs emissions in the packaging and printing industry.

Influence of water vapor on the separation of volatile organic compound/nitrogen mixture by polydimethylsiloxane membrane

In the industrial treatment of waste volatile organic compound (VOC) streams by membrane technology, a third impurity, generally, water vapor, coexists in the mixture of VOC and nitrogen or air, and can affect membrane performance and the design of the industrial process. This study focused on the investigation of the effect of water vapor on the separation performance of the separation of VOC/water/nitrogen mixtures by a polydimethylsiloxane (PDMS) membrane. Three types of VOCs: water-miscible ethanol, water-semi-miscible butanol, and water-immiscible cyclohexane, were selected for the study. Different operating parameters including, concentration of the feed VOC, feed temperature, and concentration of the feed water were compared for the separation of binary and ternary VOC/nitrogen mixtures. The interaction between the VOC and water was analyzed to explain the transportation mechanism after analyzing the difference in the membrane performance for the separation of binary and ternary mixtures. The results indicated that the interaction between the VOC (or nitrogen) and water is the key factor affecting membrane performance. Water can promote the permeation of hydrophilic VOC but prevent hydrophobic VOC through the membrane for the separation of ternary VOC/water/nitrogen mixtures. These results will provide fundamental insights for the design of the recovery application process for industrial membrane-based VOCs, and also guidance for the investigation of the separation mechanism in vapor permeation.

Enhanced hydrophobic ZSM–5 with high capacity for toluene capture under high-humidity conditions

Industrial volatile organic compounds (VOCs) have the characteristics of large displacement and high humidity. The problem of water resistance of the adsorbent in treating VOCs by adsorption method under high humidity conditions needs to be solved urgently. Herein, methyl triethoxysilane (CH3Si(C2H5O)3) and methyl trimethoxysilane (CH3Si(CH3O)3) are used for hydrophobic modification of ZSM-5, and its adsorption properties for toluene are studied under high-humidity conditions. Fourier infrared spectroscopy and X-ray photoelectron spectroscopy indicate that the hydrophobic groups –CH3 and –CH2– are successfully grafted onto the surface of the ZSM-5. The adsorption–desorption results of toluene show that the hydrophobicity of the modified ZSM-5 is remarkably improved, and the adsorption capacity for toluene is almost 6.5 times higher than that of original ZSM-5 at 80 % relative humidity. The mechanism of surface hydrophobicity modification of ZSM-5 was further investigated and found that the silicone hydroxyl group on the surface of the material reacted with the modifier to graft the hydrophobic group onto the surface of the material, which improved the hydrophobic property of the material. Moreover, the universality of the hydrophobic modification method has been proved feasible in commercial ZSM-5. Therefore, this work provides an important theory and reference for improving the hydrophobic properties of ZSM–5 molecular sieve.

Effective technology for processing industrial volatile organic compounds by the atmospheric pressure microwave plasma torch

In this study, we investigated the abatement of volatile organic compounds (VOCs) by the atmospheric pressure microwave plasma torch (AMPT). To study the treatment efficiency of AMPT, we used the toluene and water-based varnish to simulate VOCs, respectively. By measuring the compounds and contents of the mixture gas before/after the microwave plasma process, we have calculated the treatment efficiency of AMPT. The experiment results show that the treatment efficiency of AMPT for toluene with a concentration of 17.32×104 ​ppm is up to 60 ​g/kWh with the removal rate of 86%. For the volatile compounds of water-based varnish, the removal efficiency is up to 97.99%. We have demonstrated the higher potential for VOCs removal of the AMPT process.

Socioeconomic drivers and mitigating strategies of volatile organic compounds emissions in China's industrial sector

Volatile organic compounds (VOCs) emissions are becoming an increasingly serious problem in China, but little is known about the industry-specific mitigating strategies of VOCs. Using the generalized Divisia index method (GDIM) and a panel data set of China's 30 provincial-level regions from 2008 to 2017, this study is the first to explore the socioeconomic drivers of industrial VOCs emission changes in China and its 30 provincial-level regions. The contributions of provincial factors to national VOCs emission changes are compared, and each effect from 30 provincial-level regions is analyzed in detail. The results show that China's industrial VOCs emission increase over 2008–2017 was largely driven by investment scale and output scale, which was offset by the emission intensity of output, the emission intensity of investment, investment efficiency, and energy intensity. Moreover, each effect greatly varies among China's 30 provincial-level regions. The investment scale in Shandong has the largest contribution to the increase of national industrial VOCs emissions while the emission intensity of energy in Ningxia has the least contribution. Accordingly, regional disparity should be considered for formulating the strategies in aspects of investment, energy, and technology for China's industrial sector to mitigate VOCs emissions.

Improved emission factors and speciation to characterize VOC emissions in the printing industry in China

Printing industry is one of the most important sources of industrial volatile organic compound (VOC) emissions in China, and is thus a key industrial sector in terms of VOC control. However, process-based VOC emission and speciation from the printing industry have not been well identified, mainly owing to the poor emission factors (EFs) and diversity of source profiles. In this study, we systematically characterized process-based VOC emissions from the printing industry for the period of 2010–2019, through the establishment of improved emission factors and composite source profiles. VOC emissions from the printing industry were found to continuously increase from 2010 to 2018, reaching their maximum in 2018 at 939.8 Gg, but started to decrease afterwards. The substantial growth is driven by the large demand for ink and adhesive and the absence of effective control measures in the printing industry. The total VOC emissions and ozone formation potential (OFP) in China in 2019 were 916.1 Gg and 1834.5 Gg, respectively. Gravure printing and the compound process were the processes that contributed the most to both emissions and OFP. Rapidly developing provinces such as Guangdong, Jiangsu, and Zhejiang were the largest contributors to emissions. Oxygenated VOCs (OVOCs) accounted for most of the VOC emissions, followed by alkanes and aromatics, while aromatics were the dominant groups for total OFP, followed by alkenes/alkynes and OVOCs. Ethyl acetate, toluene, isopropanol, isopentane, and n-pentane were the top five VOC species in terms of emissions, while toluene, ethyl acetate, 1,3-butadiene, isopentane, and 1-butene were the top five species in terms of OFP. Scientific and precise control policy were proposed, involving four aspects: environmental access, emission standards, classification and management, and research on source substitution. We believe our study will provide an important reference for the systematic characterization and control policy of VOC emissions from other industries.

Volatile organic compound emissions from typical industries: Implications for the importance of oxygenated volatile organic compounds

Industrial productions emit large reactive volatile organic compounds (VOCs) into atmosphere, affecting tropospheric atmospheric chemistry and human health. In this study, VOC samples of industrial process and solvent use were collected from typical industries. The mass concentrations of total VOC (TVOCs) were 34.10 ± 35.46 mg m−3 (mean ± 95% C.I.) measured in industrial process and 25.39 ± 16.88 mg m−3 in solvent use. Difference of VOC profiles between industrial process and solvent use was revealed. Much higher concentrations or percentages of halocarbons were emitted from industrial process, while more abundant alkanes were measured in solvent use. The relative proportions of B:T:E (benzene, toluene and ethylbenzene) were similar for these two industrial sources, but quite different from that of combustion sources. Different ratios of F/A (formaldehyde/acetaldehyde) and A/P (acetaldehyde/propionaldehyde) were found between industrial process and solvent use, suggesting that the ratios might be used as the references to distinguish these two industrial sources. The oxygenated VOCs (OVOCs) were the largest VOC group and ranked No.1 contributor of ozone formation potentials (OFPs) in these two sources. Our results provide the source profiles of industrial VOCs and emphasize the contribution of industrial OVOCs in ozone formations.

Experimental study on toluene removal by a two-stage plasma-biofilter system

Volatile organic compounds (VOCs) are typical pollutants that affect air quality. Discharge plasma is thought to be a potential method that can remove VOCs from flue gas. In this experiment, pulsed corona discharge plasma combined with a biological tower was carried out to remove the benzene series, and toluene was selected as the typical VOC. The results indicated that the removal efficiency of toluene by pulsed corona plasma was slightly higher than that of direct current (DC) corona plasma, while its energy efficiency was much higher than DC corona plasma. Under the optimal experimental conditions of pulse voltage 8.5 kV, initial toluene concentration 1400 mg m−3, and toluene flow rate of 12 l h−1, the toluene removal efficiency reached 77.11% by the single method of pulsed corona discharge plasma, and the energy efficiency was up to 1.515 g/(kW·h) under the pulse voltage of 4.0 kV. The trickling biofilter was constructed by using the screened and domesticated Acinetobacter baumannii, and the highest toluene removal efficiency by the pulsed corona discharge plasma combined with the trickling biofilter rose up to 97.84%. Part of the toluene was degraded into CO2, H2O, and some intermediate products such as o-diphenol under the influence of Acinetobacter baumannii. When the remaining waste gas passed through the discharge plasma reactor, the benzene ring structure could be directly destroyed by the collision between toluene and plasma. Meanwhile, O·, OH·, and some other oxidizing radicals generated by the discharge also join into the oxidative decomposition of toluene and its intermediate products, thereby further improving the removal efficiency of toluene. Therefore, the two-stage plasma-biofilter system not only showed a high toluene removal efficiency, but also had a good energy efficiency. The results of this study will provide theoretical support and technical reference for industrial VOC treatment.

Synergistic Catalytic Performance of Toluene Degradation Based on Non-Thermal Plasma and Mn/Ce-Based Bimetal-Organic Frameworks.

A series of Mn/Ce-based bimetal-organic frameworks, recorded as MCDx (x = 1, 2, 4, 6), were prepared by a solvothermal synthesis method to explore their effects and performance in the synergistic catalysis of toluene under the irradiation of non-thermal plasma. The catalytic properties of different manganese loadings in MCDx for degradation of toluene were investigated. The microphysical structures of the material were analyzed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed that a MCDx coupling with non-thermal plasma can greatly improve the degradation efficiency, the energy efficiency and the CO2 selectivity, and could also significantly reduce the generation of O3 in the by-products. Among the test samples, MCD6 with Mn:Ce = 6:1 (molar ratio) showed the best catalytic performance and stability, exhibited toluene catalytic efficiency 95.2%, CO2 selectivity 84.2% and energy efficiency 5.99 g/kWh, and reduced O3 emission concentration 81.6%. This research provides a reference for the development and application of synergistic catalysis based on bimetal-organic frameworks and non-thermal plasma in the reduction of industrial volatile organic compounds.

Surface Modification by Amino Group Inducing for Highly Efficient Catalytic Oxidation of Toluene over a Pd/KIT-6 Catalyst.

Toluene is one of the typical volatile organic compounds in industry, particularly in energy and fuels production processes, which is required to be eliminated effectively to protect the environment. Catalytic oxidation of toluene is widely studied for its high efficiency, and rational design and synthesis of metal catalysts are keys for toluene oxidation. In this study, an efficient catalyst was designed and synthesized by introducing -NH2 groups on the ordered mesoporous silica (KIT-6) surface to anchor and disperse Pd species, leading to Pd nanoparticles being highly dispersed with uniform particle size distribution. Meanwhile, it was found that the introduction of -NH2 made Pd centers present an electron-rich state, and the active Pd centers could activate O2 molecules to generate more reactive oxygen species and promote the conversion of toluene, which was verified by in situ XPS and O2-TPD characterization. Compared with the catalysts prepared by an impregnation method, the catalytic performance of the Pd/NH2-KIT-6 (0.5 wt %) catalyst was significantly improved. A conversion of 90% for toluene (2400 ppm, 24,000 mL·g-1·h-1) was achieved at 171 °C, and the toluene conversion was maintained above 90% for 900 min, displaying the excellent activity and stability of the Pd/NH2-KIT-6 catalyst.

Spatially Resolved Source Apportionment of Industrial VOCs Using a Mobile Monitoring Platform

Industrial emissions of volatile organic compounds (VOCs) directly impact air quality downwind of facilities and contribute to regional ozone and secondary organic aerosol production. Positive matrix factorization (PMF) is often used to apportion VOCs to their respective sources using measurement data collected at fixed sites, for example air quality monitoring stations. Here, we apply PMF analysis to high time-resolution VOC measurement data collected both while stationary and while moving using a mobile monitoring platform. The stationary monitoring periods facilitated the extraction of representative industrial VOC source profiles while the mobile monitoring periods were critical for the spatial identification of VOC hotspots. Data were collected over five days in a heavily industrialized region of southwestern Ontario containing several refineries, petrochemical production facilities and a chemical waste disposal facility. Factors associated with petroleum, chemical waste and rubber production were identified and ambient mixing ratios of selected aromatic, unsaturated and oxygenated VOCs were apportioned to local and background sources. Fugitive emissions of benzene, highly localized and predominantly associated with storage, were found to be the dominant local contributor to ambient benzene mixing ratios measured while mobile. Toluene and substituted aromatics were predominantly associated with refining and traffic, while methyl ethyl ketone was linked to chemical waste handling. The approach described here facilitates the apportionment of VOCs to their respective local industrial sources at high spatial and temporal resolution. This information can be used to identify problematic source locations and to inform VOC emission abatement strategies.

An efficient process for aromatic VOCs degradation: Combination of VUV photolysis and photocatalytic oxidation in a wet scrubber

The elimination of volatile organic compounds (VOCs) via vacuum ultraviolet (VUV) photolysis is greatly limited by low removal efficiency and gaseous byproducts generation, while photocatalytic oxidation of VOCs suffers from catalytic deactivation. Herein, a coupled process of gaseous VUV photolysis with aqueous photocatalytic oxidation with P25 as the catalyst was firstly proposed for efficient aromatic VOCs removal (VUV/P25). The removal efficiency of toluene reached 86.2% in VUV/P25 process, but was only 33.6% and 58.1% in alone gaseous VUV photolysis and aqueous ultraviolet photocatalytic oxidation (UV/P25) process, respectively. Correspondingly, the outlet CO2 concentration in VUV/P25 process reached 132 ppmv. Toluene was firstly destructed by high-energy photons generated from gaseous VUV photolysis, resulting in its incomplete oxidation to form soluble intermediates including acids, aldehydes, esters. These soluble intermediates would be further degraded and mineralized into CO2 in subsequent aqueous UV/P25 process. Notably, the concentrations of intermediates in VUV/P25 were much lower than those in VUV photolysis, indicating the synergy effect of VUV photolysis and UV/P25 process. The stability tests proved that VUV/P25 process maintained an excellent toluene degradation performance and P25 did not suffer from catalytic deactivation. In addition to toluene, the VUV/P25 system also achieved the efficient and sustainable degradation of styrene and chlorobenzene, suggesting its good application prospect in industrial VOCs treatment. This study proposes an efficient and promising strategy for deep oxidation of multiple aromatic VOCs in industries.

Performance evaluation and prediction of activated carbon for VOCs via experiments and LFER methods

Due to the diversity and fluidity of volatile organic compounds (VOCs), it is difficult to conduct experimental studies on activated carbon (AC) used to capture VOCs in industry. Therefore, predicting the adsorption capacity of AC for VOCs is of great significance for evaluating the adsorption performance of AC and developing its promising applications. Herein, based on the experimental data of dynamic adsorption, the poly parameter linear free energy relationship (pp-LFER) model was developed to quantify the interactions between VOCs and AC. Through the dynamic adsorption curves of 25 VOCs on a fixed bed packed with the AC, the partition coefficient (PC) and adsorption capacity (q) of AC for VOCs were calculated, and the pp-LFER equations used to predict them were established. For the PC values, the pp-LFER model consists of the excess molar refractive index (E), molar polarizability (S), hydrogen-bond acidity (A), and logarithmic hexadecane-air partition coefficient (L), and the R2 of it was 0.86. For the ln q values, the developed model can predict it in R2 of 0.83, and the increased adsorption capacity was predominantly attributed to the dispersive interaction (lL). Finally, the internal and external validation results confirmed that the developed models have reliability, robustness, and predictability.