Benzene Adsorption Capacity Research Articles

Mechanistic effects of graphitization and oxygen functional groups on benzene competitive adsorption of porous carbon under high humidity conditions

Porous carbon is an ideal adsorbent for the elimination of volatile organic compounds (VOCs) attributed to their price, availability and excellent adsorption capacity. However, there are significant variation in the adsorption capacity and adsorption selectivity of different precursors for VOCs under humid conditions after modification because of the differences in their own structural properties. In this study, graphitized hydrophobic porous carbon with excellent specific surface area was successfully synthesized by selecting bamboo fiber, maize, coconut husk and coal as precursors and potassium hydroxide as an activator. Among them, the dynamic adsorption capacity of benzene in the sample with bamboo fiber as precursor was maintained at 74.7% under the high humidity condition (RH90%) compared with the dry state (RH0%). Grand Canonical Monte Carlo (GCMC) simulations and weak interaction force analyses showed that enhanced dispersion attraction between graphitized carbon surfaces and benzene molecules in comparison to disordered carbon surfaces. The existence of oxygen functional groups enhanced the interaction between porous carbon and water through hydrogen bonding leading to preferential adsorption of water molecules, which resulting in the decrease of their adsorption performance in wet condition. This research provided theoretical and experimental views of the effects of graphitization and oxygen functional groups on the competitive adsorption capture of benzene and water by porous carbon, which further provided a reliable approach to synthesizing porous carbon with high adsorption capture for benzene removal in high humidity environments.

Nitrogen-Doped High-Surface-Area activated carbon: Innovative adsorbent for enhanced SO2 and benzene removal

In this paper, we investigated the properties of nitrogen-doped activated carbon produced via the co-activation of KSCN and KOH, using hydrothermal lignin as a precursor. The resulting activated carbon exhibited a high specific surface area of 3504 m2/g and contained 3.37 % nitrogen from KSCN, which enhanced its adsorption efficiency. The adsorption capacities for SO2 and benzene at 273 K were measured at 2260.68 mg/g and 1668.90 mg/g, respectively. Competitive adsorption experiments at 298 K showed that in the presence of SO2, the activated carbon maintained a high adsorption capacity for benzene at 1008.81 mg/g, while the adsorption capacity for SO2 decreased to only 12.31 mg/g, indicating a higher affinity for benzene. The selectivity coefficient, calculated using the Ideal Adsorbed Solution Theory (IAST), reached 44.76 at a benzene-to-SO2 ratio of 2:1. To gain deeper insights into the selective adsorption mechanism, Density Functional Theory (DFT) simulations were conducted. These simulations confirmed the experimental findings, indicating that benzene can be selectively adsorbed and effectively separated from SO2 flue gas.

Synergistic SiC/Co3O4 composites for enhanced microwave-assisted benzene catalytic removal performance

Microwave-assisted catalysis is a promising technique for enhancing catalytic reactions through selective heating, potentially leading to improved reaction rates and energy efficiency. However, understanding the complex interactions between microwave absorption and catalytic performance in composite catalysts remains a challenge. In this study, Cobalt oxide(Co3O4)/silicon carbide(SiC) composite catalysts with varying SiC content were synthesized and characterized to investigate the relationship between their microwave absorption properties and catalytic performance. Quantitative analysis revealed that SiC and Co3O4 absorb microwave energy through relaxation polarization and magnetic loss mechanisms, respectively. Increasing SiC content enhanced the dielectric and magnetic loss capabilities of the composites, with the Co3O4/SiC composite containing 10 wt% SiC (Co3O4/SiC-10) exhibiting a dielectric loss tangent of 3.87 and a minimum reflection loss of −35dB. However, higher SiC content decreased the surface chemically adsorbed oxygen, surface oxygen mobility, and benzene adsorption capacity, weakening the catalytic activity under conventional heating. The Co3O4/SiC-10 sample achieved a significantly better balance between microwave absorption and catalytic performance, significantly outperforming the original Co3O4 sample under microwave irradiation. These founding establishes a quantitative research methodology that correlates dielectric loss tangent, reflection loss, and other crucial parameters with microwave absorption performance and further catalytic properties, providing insights for the rational design of catalysts that optimize both microwave absorption and catalytic activity.

Molecular simulation of different VOCs adsorption on nitrogen-doped biochar

Nitrogen-doped biochar has potential application in the removal of volatile organic compounds (VOCs) from coal-fired flue gas. To explore the adsorption characteristics of different VOCs on nitrogen-doped biochar by molecular simulation, in this study, six typical aromatic VOCs (benzene, toluene, phenol, naphthalene, p-xylene, and chlorobenzene), and an amorphous carbon model with nitrogen/oxygen groups were selected and constructed. Grand Canonical Monte Carlo (GCMC) simulations were performed to evaluate the adsorption capacities of VOCs on nitrogen-doped biochar. The results showed that the optimized carbon model was in good agreement with the pore structure parameters of nitrogen-doped biochar, and the agreement of toluene adsorption capacities was more than 80 % at room temperature. The adsorption capacity of nitrogen-doped biochar for different VOCs was 184 − 317 mg/g with the order of phenol > naphthalene > p-xylene > toluene ≈ benzene ≈ chlorobenzene (single-component adsorption). Among them, the phenol molecule is more easily adsorbed due to its strong polarity, resulting in stronger electrostatic interaction with the adsorbent. The decrease rate of benzene adsorption capacity is the lowest with increasing adsorption temperature because of its low molecular weight. As gas concentration increases, van der Waals interactions between molecules and between molecules and porous carbon also increase, leading to an increase in VOCs adsorption capacity. Nitrogen-doped biochar not only has the highest VOCs/N2 selective adsorption coefficient for phenol (up to 36) but also has the highest adsorption capacity of 63 mg/g when 6 kinds of VOCs are multi-component adsorption at 25 °C. This study can provide references for the practical application of adsorption method in the removal of VOCs from coal-fired flue gas.

Insights into the removal of volatile organic compounds by three-dimensional ordered microporous zeolite-templated carbon: A combined experimental study and density functional theory calculation

Volatile organic compounds (VOCs) threaten human health and the ecological environment, requiring to be removed timely. Zeolite-templated carbon with and without sulfur (ZTC and S-doped ZTC) was prepared by the chemical vapor deposition (CVD) method in a rotating bed reactor and used to remove VOCs. ZTC samples showed narrow and ordered microporous structure (0–2 nm), high specific surface area (2049.05–1732.06 m2/g), abundant pore volume (1.28 – 1.16 cm3/g), and uniform sulfur distribution (S-doped ZTC). Afterwards, the VOCs adsorption capacity was tested at 30, 60, and 90 °C. The results showed that S-doped ZTC exhibited higher benzene (138.2 mg/g) and toluene (171.8 mg/g) adsorption capacities at 30 °C than those performed at 60 and 90 °C owing to the exothermic process. Moreover, S-doped ZTC showed better VOCs adsorption capacity than ZTC-RC due to the combination of physical and weak chemical adsorption. Subsequently, S-doped ZTC captured more toluene (171.8 mg/g) than benzene (138.2 mg/g) because of the dipole–dipole interaction. Furthermore, Fourier transform infrared spectrum (FTIR) and density functional theory (DFT) calculation revealed that inorganic components (NH3, NO, and SO2) imposed a negative effect on VOCs adsorption due to the comparative adsorption. This study offered insights into how ZTC structure and sulfur modification affected the adsorption of VOCs, providing a reliable guideline for the preparation and utilization of adsorbents used to remove VOCs.

Evaluation of Benzene Adsorption onto Grass-Derived Biochar and Comparison of Adsorption Capacity via RSM (Response Surface Methodology)

The present study reports the effective removal of benzene in aqueous phase onto biochar. The adsorption capacity of benzene onto biochars made at different pyrolytic temperatures (e.g., 350, 550, and 750 °C) and from various feedstocks (e.g., grape pomace, rice husk, and Kentucky bluegrass) were investigated. The adsorption capacity of Kentucky bluegrass-derived biochar (KB-BC) prepared at 550 °C for benzene was better than other biochars, owing to the higher surface area and functional groups. The adsorption isotherms and kinetics model for benzene by KB-BC550 fitted the Freundlich and pseudo-first order, respectively. In addition, the results of response surface methodology (RSM) designed with biochar dose, reaction time, and benzene concentration showed the maximum adsorption capacity (ca. 136 mg BZ/g BC) similar to that from kinetic study. KB-BCs obtained as waste grass biomass may be a valuable adsorbent, and RSM may be a useful tool for the investigation of optimal conditions and results.

Heat-acid treatment of georgian and kazakhstani natural heulandite-chabazites

The article considers the processes leading to a change in the structure and properties as a result of thermal treatment followed by acid treatment of natural zeolites from the Rkoni plot of the Tedzami deposit, Georgia, containing up to 80% of heulandite and 10% of chabazite, and from the Chankanay deposit, Kazakhstan, containing up to 70% of heulandite-chabazite mixture, selected for the creation of new bactericidal zeolite filter materials for purification and desinfection of water from various sources. The influence of preliminary heat treatment of the studied natural zeolites on weight loss, the processes of dealumination and decationization during subsequent acid treatment, and the adsorption properties of the final products is described. It has been shown that mass loss is minimal for amorphized samples, dealumination and the participation of sodium ions in the decationization process slow down significantly, and the adsorption capacity for water and benzene sharply decreases with increasing calcination temperature; all these effects are clearly pronounced for heulandite-containing Rkoni tuff, and for the more acid-resistant Chankanay zeolite they are manifested to a lesser extent.

Effect of pore size distribution of biomass activated carbon adsorbents on the adsorption capacity

AbstractBACKGROUNDIn order to investigate the correlation between the pore size distribution of biomass activated carbon adsorbents (BACAs) and VOCs (volatile organic compounds) adsorption/desorption performance. Four BACAs with same specific surface area but different pore size distribution were prepared under different experimental conditions and processes.RESULTSThe impact of the pore size distribution of BACAs on the adsorption/desorption performance of benzene, toluene and xylene was investigated. The results indicated that the adsorption ability of the prepared BACAs for benzene, toluene and xylene was mostly affected by the pore sizes distributed in the 2.60 ~ 3.25, 2.68 ~ 3.35and 4.20 ~ 4.90 nm ranges, respectively, when the studied BACAs had similar specific surface area (SBET ≈ 1080 m2 g−1). However, the desorption amount of adsorbed benzene molecules mainly relied on the pore structures of BACAs having pore sizes in the 3.95 ~ 4.60 nm range.CONCLUSIONThe pore structures of BACAs distributed in different pore size ranges have various effects on the phenyl VOCs adsorption capacity. Benzene adsorption on the BACAs was mainly affected by the microporous structures. The pore structure with larger pore size was more favorable for the desorption of the adsorbed toluene and xylene molecules compared to the adsorbed benzene molecules. Benzene, toluene and xylene had low residual rates in the studied activated carbon adsorbents attesting to their superior regenerative properties. This work could provide an important reference for the design, preparation, and selection of activated carbon adsorbents for the adsorption capacity of benzene, toluene and xylene. © 2024 Society of Chemical Industry (SCI).

Interior and Exterior Surface Modification of Zr-Based Metal-Organic Frameworks for Trace Benzene Removal.

The emission of volatile organic compounds (VOCs) significantly contributes to air pollution and poses a serious threat to human health. Benzene, one of the most toxic VOCs, is difficult for the human body to metabolize and is classified as a Group 1 carcinogen. The development of efficient adsorbents for removing trace amounts of benzene from ambient air is thus of great importance. In this work, we studied the benzene adsorption properties of four Zr-based metal-organic frameworks (Zr-MOFs) through static volumetric and dynamic breakthrough experiments. Two previously reported Zr-MOFs, BUT-12 and STA-26, were prepared with a tritopic carboxylic acid ligand (H3L1) functionalized with three methyl groups, and STA-26 is a 2-fold interpenetrated network of BUT-12. Two new isoreticular Zr-MOFs, BUT-12-Et and STA-26-Et, were synthesized using a similar ligand, H3L2, where the methyl groups are replaced with ethyl groups. There are mesopores in BUT-12 and BUT-12-Et and micropores in STA-26 and STA-26-Et. The four Zr-MOFs all showed high stability in liquid water and acidic aqueous solutions. The microporous STA-26 and STA-26-Et showed much higher benzene uptakes than mesoporous BUT-12 and BUT-12-Et at room temperature under low pressures. Particularly, the benzene adsorption capacity of STA-26-Et was high up to 2.21 mmol/g at P/P0 = 0.001 (P0 = 12.78 kPa), higher than those of the other three Zr-MOFs and most reported solid adsorbents. Breakthrough experiments confirmed that STA-26-Et could effectively capture trace benzene (10 ppm) from dry air; however, its benzene capture capacity was reduced by 90% under humid conditions (RH = 50%). Coating of the crystals of STA-26-Et with polydimethylsiloxane (PDMS) increased the hydrophobicity of the exterior MOF surfaces, leading to a more than 2-fold improvement in its benzene capture capacity in the breakthrough experiment under humid condition. PDMS coating of STA-26-Et likely slowed down the water adsorption process, and thus, the adsorbent afforded more efficient capture of benzene. This work demonstrates that modifying both the interior and exterior surfaces of MOFs can effectively enhance their performance in capturing trace benzene from ambient air, even under humid conditions. This finding is meaningful for the development of new adsorbents for effective air purification applications.

Unveiling platinum's electronic and dispersion impacts for enhanced benzene combustion: From nanoparticles to nanoclusters and single atoms

Catalytic combustion using platinum (Pt) supported on metal oxides emerges as an eco-friendly approach for benzene removal. However, relationships between Pt dispersion, adsorptive properties, and reactivity across overall Pt size regimes remain unclear, as many previous studies have focused on only one or two Pt size ranges. This study systematically examines the oxidation state, electron density, and resulting adsorptive properties of Pt across a range of sizes, including isolated atoms, sub-nanometer clusters, and nanoparticles. The as-synthesized Pt/Fe2O3 catalysts with defined Pt dispersion and electronic states on faceted Fe2O3 supports. Benzene combustion kinetics are measured over Pt entities from single atoms to sub-nanometer clusters and 2 nm particles, elucidating mechanisms and structure–reactivity links. Findings reveal surprising non-monotonic activity trends that deviate from dispersion features, with an order of: Pt sub-nanometer clusters < Pt single atoms < Pt nanoparticles. Despite high dispersion, single Pt atoms and nanoclusters exhibit lower benzene combustion activity than 2 nm Pt particles on Fe2O3. This reduced activity stems from diminished adsorptive affinity of single atoms and nanoclusters for benzene and O2, tracing back to their oxidized Pt valence states. In contrast, 2 nm Pt particles show excellent benzene and oxygen adsorption capacities enabled by metallic Pt ensembles, thus maximizing reactivity. Additional insights indicate single Pt atoms supported on Fe2O3 avoid competitive benzene/O2 adsorption through a non-competitive mechanism, moderately enhancing performance versus nanoclusters with competitive adsorption. However, Pt valence state has a greater impact than adsorption mechanisms, as Pt nanoparticles are considerably more active than single atoms and nanoclusters. In situ analysis proposes plausible benzene decomposition routes over active Pt sites. The novel findings that fine-tuning Pt dispersion and electronic structure—along with kinetic mechanisms—lead to significant variations in benzene combustion reactivity will assist rational design of efficient Pt catalysts for benzene elimination.

Interfacial quantum chemical characterization of aromatic organic matter adsorption on oxidized microplastic surfaces

Examining the adsorption efficiency of individual contaminants on microplastics (MPs) is resource-intensive and time-consuming. To address this challenge, combined laboratory adsorption experiments with model simulations were performed to investigate the adsorption capacities and mechanisms of MPs before and after aging. Our adsorption experiments revealed that aged polyethylene (PE) and polyvinyl chloride (PVC) MPs exhibited increased adsorption capacity for benzene, phenol, and naphthalene. Additionally, density functional theory (DFT) simulations provided insights into changes in adsorption sites, adsorption energy, and charge density on MPs. The π bond of the benzene ring emerged as a pivotal factor in the adsorption process, with van der Waals forces exerting dominant influence. For instance, the adsorption energy of benzene on pristine PE was −0.01879 eV. When oxidized groups, such as hydroxyl, carbonyl, and carboxyl, on the surface of aged PE became the adsorption sites, the adsorption energy increased to −0.06976, −0.04781, and −0.04903 eV, respectively. Regions with unoxidized functional groups also exhibited higher adsorption energies than pristine PE. These results indicated that aged PE had a stronger affinity for benzene compared to pristine PE, enhancing its adsorption. Charge density difference and energy density of states corroborated this observation, revealing larger π-bond charge accumulation areas for benzene on aged PE, suggesting stronger dipole interactions and enhanced adsorption. Similar trends were observed for phenol and naphthalene. In summary, the DFT calculations aligned with the adsorption experiment findings, confirming the effectiveness of simulation methods in predicting changes in the adsorption performance of aged MPs.

Linker Engineering in Mixed-Ligand Metal-Organic Frameworks for Simultaneously Enhanced Benzene Adsorption and Benzene/ Cyclohexane Separation

The development of metal-organic frameworks (MOFs) that simultaneously possess high adsorption capacity and selectivity for benzene (Bz)/cyclohexane (Cy) separation is a formidable challenge. In this study, we employ the mixed-ligand...

Upcycling of aureomycin hydrochloride residue into highly meso-microporous carbon with remarkable adsorption capacity for benzene capture

The exploration of high-value utilization of antibiotic bacteria residues is of great importance at the environmental and resource levels. In this study, we report an aureomycin hydrochloride residue-derived activated carbon and its application in the adsorption of hazardous benzene. Self-N-doped activated carbon with excellent benzene adsorption properties was prepared by K2CO3-assisted activation pyrolysis using aureomycin hydrochloride residue as carbon and nitrogen sources. It is found that the pore structure and the benzene adsorption behavior could be optimized through regulating the mass ratio of K2CO3 to carbon (mK2CO3/mC) and the activation temperature. Under the pyrolysis conditions of mK2CO3/mC = 3:1 and 800 ºC, the specific surface area and total pore volume of the as-prepared carbon reached 1564 m2 g−1 and 0.70 cm3 g−1, respectively, whereas those of the micropores were 1440 m2 g−1 and 0.48 cm3 g−1, respectively, implying that the proportion of micropores reached 68.6%. The adsorption capacity of benzene based on the optimal adsorbent (AHRC-3PC-800) was as high as 1303 mg g−1 at 25 ºC and relative pressure (P/P0) of 0.9–1. Therefore, the aureomycin hydrochloride residue-based activated carbon adsorbent has a broad application prospect in the removal of volatile organic compounds.

Enhanced adsorption of aromatic VOCs on hydrophobic porous biochar produced via microwave rapid pyrolysis

To customize biochar suitable for efficient adsorption of benzene derivatives, this study presents programmed microwave pyrolysis to produce hydrophobic porous biochar with low-dose ferric chloride. Designated control of the ramping rates in the carbonization stage and the temperatures in the activation stage were conducive to enlarging the specific surface area. Iron species, including amorphous iron minerals, could create small-scale hotspots during microwave pyrolysis to promote microporous structure development. Compared with conventional pyrolysis, programmed microwave pyrolysis could increase the specific surface area from 288.6 m2 g−1 to 455.9 m2 g−1 with a short heating time (15 min vs. 2 h) under 650 °C. Engineered biochar exhibited higher adsorption capacity for benzene and toluene (136.6 and 94.6 mg g−1), and lower adsorption capacity for water vapour (6.2 mg g−1). These findings provide an innovative design of engineered biochar for the adsorption of volatile organic compounds in the environment.

A novel MOF-based hollow carbon nanofiber mat with hierarchical apertures for efficient adsorption of low concentration benzene under high humidity

An ultraporous metal-organic framework (MOF)-based carbon nanofiber mat (CNFM4) with two types of hollow structure was prepared by electrospinning the mixed solution with polyacrylonitrile, polymethyl methacrylate and ZIF-8, followed by carbonization. The self-supporting CNFM4 has a higher Brunauer-Emmett-Teller (BET) specific surface area (SBET) (935.5 m2/g) and total pore volume (Vtotal) (0.69 cm3 g−1) than the PAN, PAN/PMMA, PAN/ZIF-8-derived carbon nanofiber mats (CNFMs). Static adsorption experiment showed CNFM4 had a high benzene adsorption capacity of about 12 mmol g−1 at saturated vapor pressure at 298 K, due to its high Vtotal. And even at low pressure of 0.1 kPa, its adsorption capacity still reached 2.75 mmol g−1, owing to its high SBET and rich micropore. The dynamic adsorption study showed CNFM4 has a breakthrough and saturation adsorption amount of 0.4902 and 0.5714 mmol g−1 at dry gas, respectively, and even at 60 RH%, they still can keep 0.2620 and 0.3642 mmol g−1, respectively, suggesting its application potential under the actual environment. The dynamic adsorption study also proves the important role of hollow structure at improving adsorption rate. This work provides a new idea for preparing the ultraporous MOF-based hollow CNFMs, and broadens the application of MOF-based CNFMs for VOCs removal.

The Influence of Activation Technique on the Adsorption of Coconut Coir-Activated Carbon in Four Potentially Dangerous Liquids

Coconut coir is one of the agricultural waste. According to the research it was utilized as an activated carbon. Activated carbon is produced by high temperatures and chemical. Activation process will be carried out by two types of chemical activators i.e. phosphoric acid and potassium hydroxide in 10%. The temperature at 750°C and using three time activation is about 60, 90 and 120 minutes. The result showed that phosphoric acid give the highest yield (42%) with a greater fixed carbon content (69%) than potassium hydroxide activation. As a result of activation with phosphoric acid and potassium hydroxide, the iod absorption value of activated carbon from coconut coir was 770 mg/g and 736 mg/g, respectively. Four potentially hazardous liquids, which revealed that activated carbon derived from phosphoric acid activation had the greatest adsorption capacity for chloroform. In contrast, activated carbon produced from potassium hydroxide activation has greater formaldehyde, ammonia, and benzene adsorption capacities. The findings of the study revealed that the iodine adsorption capacity of activated carbon obtained from the activation of phosphoric acid and potassium hydroxide was comparable (770 and 736 mg/g), indicating a different adsorption preference. Although the adsorption capacity of activated carbon iodine produced by phosphoric acid activation was greater, it was only superior to chloroform compared to the adsorption capacity of activated carbon produced by potassium hydroxide activation at the same concentration, temperature, and activation period. The results of the investigation indicate that the activator has a considerable effect on the adsorption preference of the activated carbon that is produced.

Improving the adsorption performance of non-polar benzene vapor by using lignin-based activated carbon.

Both indoor and outdoor contamination continually contain benzene vapor. It has primary concerns about long-term health risks to the living environment. Benzene is a crucial airborne pollutant in the environment due to its apparent acute toxicity, high volatility, and poor degradability. It is especially urgent to restrain benzene emissions due to the persistent concentration increase and stringent processes. Benzene adsorption is a highly efficient mechanism with low cost, low energy consumption, and a simple process. In this study, biomass-derived porous carbon materials (TCACs) were synthesized by pyrolysis activation combined with H3PO4, HNO3, and HCl. TCAC44 has the best activation conclusion, showing that surface area and pore volume were 1107 m2/g and 0.58 cm3/g treated with H3PO4 and so was chosen for subsequent benzene adsorption/desorption tests. The adsorption capacities of benzene for TCAC44 were increased from 58 mg/g for 35 °C + 95% RH to 121 mg/g for 25 °C + 15% RH and presented a higher adsorption capacity of benzene than TCAC101 and TCAC133. Otherwise, well recyclability of TCAC44 was revealed as the benzene adsorption capacity reductions were 22.49% after five adsorption-desorption cycles. Furthermore, the present study established the property-application relationships to promote and encourage future research on the newly synthesized innovative TCAC44 for benzene removal.

Development of a novel hierarchical porous and hydrophobic silica from montmorillonite for benzene adsorption

A hierarchical porous and hydrophobic adsorbent is the key to removing the volatile organic compounds through adsorption technology, especially under humidity conditions. In this work, we synthesized a hierarchical porous and hydrophobic montmorillonite-derived adsorbent by a facile strategy, i.e., a combination of ball milling, acid activation, and thermal treatment. Our results showed that ball milling could efficiently grind the montmorillonite sheets into small fragments, which caused the rapid dissolution of octahedral cations from the edges of these fragments during the subsequent acid activation process. The resulting porous silica showed more porosity (including micropores and mesopores) and a larger specific surface area (664 m2 g−1), compared with the product (345 m2 g−1) obtained by only acid washing without ball milling. The next thermal treatment readily removed the surface hydroxyl of porous silica, leading to the formation of the target product (HP-SiO2) with enhanced hydrophobicity and well-preserved pore structures. As an adsorbent for benzene molecules, HP-SiO2 exhibited a high dynamic benzene adsorption capacity (257.1 mg g−1) due to the large specific surface area and abundant micropores. Furthermore, HP-SiO2 maintained outstanding benzene adsorption performance under different humidity conditions (with a high adsorption capacity of 185.0 mg g−1 even under 40% relative humidity). Our work provided a low-cost and facile strategy for the synthesis of hierarchical porous and hydrophobic silica materials, and this adsorbent would serve as a promising adsorbent for the elimination of practical volatile organic compounds.

Hierarchical porous carbon with tunable apertures and nitrogen/oxygen heteroatoms for efficient adsorption and separation of VOCs

Porous carbon materials are good adsorbent candidates for removing volatile organic compounds (VOCs) due to their reliability and cost-effectiveness. Especially, the pore size distribution (PSD) of porous carbon materials plays a critical role in VOCs adsorption and separation. In this study, we present benzimidazole-derived porous carbons (BICs) with controllable pore size and oxygen/nitrogen heteroatoms. The pore size is controlled by adjusting the reaction degree of inorganic salt (K2CO3) and nitrogen-containing groups in the system. The tunable pore size distribution makes BICs highly efficient for the adsorption and separation of VOCs. BIC-3-900 exhibits a dominant pore size distribution of 3.0–4.0 nm and an exceptionally high total pore volume of 2.42 cm3/g, leading to ultra-high adsorption capacities for benzene and methanol (22.19 and 52.65 mmol/g, respectively) at 293 K. In addition, BIC-1-700 dominated by the micropore size is more favorable for adsorbing low-concentration small molecule VOCs (with a dynamic adsorption capacity of 4.21 mmol/g for methanol at 3800 ppm). In terms of the adsorptive separation performance, BIC-1-900 has an efficient benzene/methanol selectivity (∼30.13) due to its PSD (1.2–2.0 nm) which was more favorable for capturing low-concentration benzene. Moreover, both experimental and simulation (GCMC and DFT) results demonstrate that the abundant N/O heteroatoms doping in BIC-1-700 results in charge heterogeneity and stronger electrostatic affinity for polar VOCs molecules. Herein, our findings suggest that BICs with controllable pore size and oxygen/nitrogen heteroatoms have significant potential in practical VOCs capture and separation.

Comparison of the gaseous benzene adsorption capacity by activated carbons from Fraxinus excelsior L. as a lignocellulosic residual

Comparison of the gaseous benzene adsorption capacity by activated carbons from Fraxinus excelsior L. as a lignocellulosic residual