Adsorption Of Organic Compounds Research Articles

Enhanced VOCs adsorption with UIO-66–porous carbon nanohybrid from mesquite grain: A combined experimental and computational study

In this study, adsorption of volatile organic compounds (VOCs) (here just gasoline vapor) by activated carbon- modified UIO-66 was investigated. First, activated carbon prepared from mesquite grain (ACPMG) and then UIO/ACPMG nanohybrid was synthesized by the solvothermal method. In following, the effect of main key parameters which effect on the surface and adsorption capacity such as the ratio of ACPMG to UIO-66 was studied. Physiochemical changes of as- synthesized samples were investigated by TGA, HR-TEM, PSD, SEM, EDX/MAP, BET, FT-IR, XRD, and XPS. It was found the UIO/ACPMG20% nanohybrid had the highest adsorption capacity (391.304 mg/g) for VOCs compared with the other samples, while the adsorption capacity of UIO-66, UIO/ACPMG10% nanohybrid, and UIO/ACPMG30% nanohybrid was 298.871, 309.523, and 320 mg/g respectively. UIO/ACPMG20% nanohybrid desorbed 285.71 mg/g of the adsorbed gasoline, which is an excellent result in desorption. So, the sample of UIO/ACPMG20% nanohybrid was selected as the optimum nano-adsorbent. In other hand, all the nano-adsorbent showed a rapid kinetic behavior for gasoline vapor adsorption and the maximum time for reaching a high adsorption capacity approximately was obtained in 20 min. Density functional theory calculations also performed to understand the adsorption characteristics of gasoline vapor on activated carbon-modified UIO-66.

A theoretical insight into the adsorption behavior of organic molecules on MoS2 monolayer

AbstractThe adsorption stage is crucial in sensing performance and photoreaction on material surfaces. This study investigates volatile organic compounds (VOC) adsorption on MoS2 monolayer using first‐principle calculations. The adsorption configurations are stabilized by H···S hydrogen bonds and C/O···S intermolecular interactions. The process of molecules attached to MoS2 is evaluated as weak physical adsorption and decreases in ordering 1‐propanol > isopentane > acetone > propenal ≈ ethylamine. Besides, AIM analysis indicates that the H···S and C/O···S contacts are weak interactions and are non‐covalent in nature. The intermolecular hyper‐conjugation energy values resulting from the NBO approach determine the stronger hydrogen bonds of H···S in comparison to C/O···S interactions. Remarkably, the gas sensing response of the MoS2 monolayer for VOC molecules is observed theoretically. The sensing responses of gas molecules on the MoS2 monolayer are achieved considerably, up to 99.80% for ethylamine, 97.96% for acetone, and 18–32% for the remaining gases. The MoS2 monolayer is expected to be a suitable sensing material for VOC.

Construction of hydrophobic HKUST-1 in wood with selective adsorption performance for toluene and moisture blends

The effect of moisture on the volatile organic compound (VOC) adsorption on biomass-derived metal–organic framework composites is significant in practical applications. In this study, wood-based metal organic frameworks (MOF199-W) and hydrophobic MOF199-W (HMOF199-W) were developed using HKUST-1 (MOF199) and long alkyl chains to investigate the adsorption performance of toluene and enhance the selectivity of adsorption under high humidity conditions. The results demonstrated that HKUST-1 could be anchored onto the surface of wood vessels and fibers through coordination with Cu2+, resulting in an improved surface area in comparison to natural wood. The toluene adsorption capacity of MOF199-W with a 20 % loading was comparable to that of an equivalent amount of MOF199, with adsorption capacities of 323.5 mg/g and 369.9 mg/g, respectively. Further, the Yoon-Nelson model was found to adequately describe the dynamic adsorption process. Following the introduction of long alkyl chains, MOF199 and MOF199-W were endowed with strong hydrophobic character (water contact angle of 107.0◦, 104.0◦, and water uptake of 30.5 mL/g, 55.3 mL/g). With the increase in humidity, the adsorption performance of MOF199 and MOF199-W for toluene sharply decreased, but HMOF199 and HMOF199-W still maintained the adsorption capacities at 304.7 mg/g and 226.7 mg/g, even under 80 % RH conditions. Therefore, HMOF199-W has shown great potential in wooden building materials with the ability for toluene capture under humid conditions.

Exploration of the adsorption and desorption performance of volatile organic compounds by activated carbon with different shapes based on fixed-bed experiments

Activated carbon (AC) has been widely used in volatile organic compounds (VOCs) treatment of industrial exhaust gases. Rather than modifying specific pore size distributions and surface properties, altering the shape of AC offers a more feasible approach to enhance its adsorption performance. This study investigates the adsorption-desorption performance of two different shaped ACs with highly similar properties for the removal of VOCs. The clover-shaped AC (CSAC) has a 27.46% lower internal void fraction and a 39.10% higher external void fraction compared to cylindrical AC (CAC), resulting in denser packing and longer contact time with VOCs. Adsorption experiments showed the CSAC has 40% longer adsorption breakthrough (BT) times for ethanol, ethyl acetate, and n-hexane on average, and 20% higher saturation adsorption capacity per unit volume. CSAC also has higher partition coefficients, with the highest values for ethanol, ethyl acetate, and n-hexane being 0.0187, 0.0382, and 0.0527 mol kg−1·Pa−1, respectively. The desorption process for selected VOCs is non-spontaneous and endothermic. Optimal desorption conditions were identified as an inlet space velocity of 3535 h−1, a desorption temperature of 150 °C, and a pulsed inlet method. To investigate the possibility of the application of CSAC in real-world scenarios, xylene was chosen as a representative industrial VOC. Results showed CSAC has 20% higher BT time and saturation adsorption capacity for xylene compared to CAC under different bed heights. The desorption efficiency for xylene on both ACs is below 40%. With increasing xylene inlet concentration, the mass transfer zone (MTZ) height initially increases but stabilizes beyond 1704 mg m−3. At identical bed heights, the MTZ height of CSAC is 29% shorter than CAC, indicating a higher bed utilization efficiency.

3D hydrophobic wood membrane with micro-nano baffle structure for multifunctional air purification filters: “Kill three eagles with one arrow”

Air pollution has presented an imminent threat to the world. Multifunctional filters with high filtration efficiency, low pressure drop, moisture resistance, antibacterial properties, and renewability are urgently needed to be developed. In this study, multifunctional wood filters are innovatively designed with a baffle structure combining macroscopic structural design and microscopic in-situ synthesis of silver nanoparticles (Ag NPs). The filter has excellent particle removal efficiency (PM0.3, 98.5 %), exceptional volatile organic compounds (VOCs) adsorption efficiency (98.4 % for formaldehyde and 91.7 % for xylene), high sterilization efficiency (99.99 %) and excellent regeneration ability (performance recovery to 98 % of the initial). Furthermore, personal protective masks were assembled by the prepared filters, whose process of replacing element is as simple as replacement of electric mosquito incense tablets. This innovative filter holds promise for applications such as daily protection, sudden accidents and prevention and control of respiratory infectious diseases. We envision that the functionally modified Ag NPs wood filters with a multilayer structure offer a comprehensive solution for more effective air purification in polluted environment.

Influence of super activated renewable carbon (SARC) on the adsorption of volatile organic compounds (VOCs) in low-carbon composites (LCCs)

This is the first study of the adsorption of volatile organic compounds (VOCs) onto super activated renewable carbon (SARC), so as to maximize the odor removal during the low-carbon composites (LCCs) compounding. Three different sized SARC samples were prepared by alkali (NaOH) modification of coconut-shell derived renewable carbon: small (S-SARC), medium (M-SARC) and large (L-SARC). Their structural properties were investigated to explore their performance on VOCs removal. The migration behavior of SARC particles was simulated to homogenize the particles’ distribution for better contact with VOCs molecules. The adsorption was evaluated by gas chromatography-mass spectroscopy (GC/MS) to quantify the emitted VOCs. Both Langmuir and Freundlich isotherms were applied, and the influence of chemical and physical properties of SARC on the adsorption capacity were compared. The results confirmed the dominant chemical adsorption, and Freundlich adsorption isotherm was suggested under the circumstances of high temperature compounding. Thus, using SARC, especially S-SARC can significantly enhance the removal of odorous VOCs and promote the LCCs in substituting the fossil-based plastics.

Humid-Air Regeneration of Microporous Adsorbents at Ambient Temperature for Cyclic Dynamic Adsorption of Volatile Organic Compounds: A Comparison with Thermal Regeneration

Humid-Air Regeneration of Microporous Adsorbents at Ambient Temperature for Cyclic Dynamic Adsorption of Volatile Organic Compounds: A Comparison with Thermal Regeneration

Unveiling the Role of Hydrophobicity on Multilayer Carbon Nanosheets Enriched in sp2-Carbon for Toluene Adsorption under Humid Conditions.

Carbon materials are regarded as a promising adsorbent for the adsorption of volatile organic compounds (VOCs). However, their adsorption behaviors are usually compromised at ambient conditions, attributed to the competitive VOCs adsorption with water vapor. In this study, we demonstrated that the selectivity for toluene than water of carbon can be effectively enhanced by introducing more sp2-carbon with two-dimensional nanosheets stacked. The multilayer carbon nanosheets enriched with sp2-carbon (CNS-MCA) exhibit a 151° H2O-contact angle, indicating hydrophobicity. Dynamic adsorption behaviors revealed that CNS-MCA retain 71% of their toluene adsorption capacity (91 mg/g) even at 60% relative humidity. Density functional theory (DFT) calculations, static adsorption studies, in situ Raman spectroscopy, and time-resolved in situ nuclear magnetic resonance (NMR) spectroscopy collectively indicate that toluene exhibits enhanced adsorption and selectivity due to π-π* interactions between its aromatic rings and the sp2-carbon. Conversely, water adsorption is attenuated, attributed to the reduced availability of surface-exposed hydrogen bonds associated with sp2-carbon and the inherent hydrophobic nature of multilayer graphene. This study extends a novel solution for the enhancement of VOCs adsorption under humid conditions.

Application prospects of graphene in environmental science

Nanomaterials and graphene, as cutting-edge materials, have play a crucial role in environmental governance. The introduction of nanomaterials brings new hope to environmental governance. Graphene not only improves the efficiency and cost-effectiveness of water treatment but also drives innovation and development in environmental technologies. This article provides a summary and analysis review starting from the characteristics of nanomaterials and Graphene, comprehensively reviewing Graphenes advantage in environmental technologies and discovered its application in this area. The research summarized the conclusion that Graphenes characteristics make it suitable for addressing environmental issues such as water pollution, its composites can play an important role in water treatment process including water purification, heavy metal adsorption, organic compound adsorption and removal through different preparation and reaction mechanisms. By introducing Nanopore structures and artificially designed stacking structures on graphene membranes, the permeation performance could be modulated and improved. By the way of physical and chemical adsorption, ion exchange, electrochemical and photocatalysis, Graphene and its oxide could be applied to remove heavy metal ion and organic substances from polluted water. The article also introduced the main preparation methods of Graphene and its potential secondary pollution problem. This article provides valuable insights for scientific research and engineering practices in environmental protection and sustainable development.

Laser ablation and chemical vapor deposition to prepare a nanostructured PPy layer on the Ti surface

Abstract The deposition of polypyrrole (PPy) on a Ti surface is commonly employed to enhance the material’s properties for different applications such as supercapacitors, biomedicine, and corrosion resistance. Instead of complex or costly polymerization procedures for the PPy synthesis on the Ti metal surface, we utilized the effect of a simple and inexpensive laser ablation of the Ti surface in the open-air environment to prepare a hydrophilic TiO2 surface. In this condition, a thin PPy layer with remarkable nanostructures such as nanorings (∼80 nm) and nanotubes (∼245 nm) was deposited on a selective and desired pattern of ablated Ti areas through the chemical vapor deposition process using ferric chloride (FeCl3) solution as a pyrrole oxidizer. Raman and X-ray photoelectron spectroscopy (XPS) analyses confirmed the PPy formation on the Ti surface. The creation of these nanostructures was due to the micro/nanomorphology of the ablated Ti substrate. Water contact angle (WCA) measurements indicated the hydrophobic behavior of the PPy/Ti surface by the aging effect after 24 weeks with the change of WCA from 20° to 116°. The change in the surface chemical composition upon adsorption of airborne organic compounds with the long-term storage of PPy/Ti surface in air was studied by the XPS test.

Magnetic adsorbents from co‐pyrolysis of non‐woody biomass and red mud for water decontamination

AbstractRed mud (RM) and non‐woody biomass are both underutilized resources for renewable composite materials, which could be used in environmental decontamination processes. This study aims to investigate the efficacy of co‐pyrolyzing non‐woody biomass with RM to produce a magnetic biochar composite. When pyrolyzed, RM is reduced to magnetic iron while the non‐woody biochar is responsible for the adsorption of organic compounds. Ibuprofen, acetaminophen, methyl orange, and methylene blue were used as test compounds to investigate the overall adsorptive capacity of the composite and to determine the possible adsorption mechanisms of biochar produced from RM pyrolyzed with switch grass, phragmites, rice husk, and miscanthus. The composite produced from a 1 to 1 mixture of RM and miscanthus showed the highest adsorption capacity with 13.8 and 8.34 mg/g of ibuprofen and acetaminophen adsorbed, respectively, which is attributed to its greater ‐interactions as a result of lower surface oxygen sites. Different ratios of RM to biomass were also tested for the production of the miscanthus composite, where it was found that the 1:2 ratio showed the best overall adsorption with 25.9 mg/g removal of acetaminophen, surpassing the miscanthus biochar's at 17.9 mg/g.

Gas-Solid flow and mass transfer characteristics in activated carbon adsorption equipment: The impact of structural outline

The efficacy of adsorption of volatile organic compounds (VOCs) in industrial emissions by activated carbon (AC) is influenced by adsorption kinetics and hydrodynamics. To simulate the performance of continuous flow AC adsorption process, a computational fluid dynamics (CFD) model that includes both multiphase flow and adsorption kinetics was developed. Because of its well-understood adsorption mechanism, N-butane was chosen as the target contaminant in this investigation. Simulation results revealed that velocity distribution uniformity is deeply affected by structural outline. According to simulations of the heat and mass transfer process, the adsorption reaction stoichiometric constraints between n-butane and AC were achieved; however, full utilization of AC was difficult to reach because of the hindered heat accumulation and mass transfer diffusion. Different structural outline leads to a 2.15 % improvement of adsorption efficiency due to an enhancement in the velocity distribution uniformity. The CFD model adequately describes the breakage curve occurring in the gas-solid multiphase flow system and confirms that heat and mass transfer is the rate limiting step in contaminant adsorption. This article investigates the effects of velocity distribution, heat and mass transfer on adsorption efficiency in equipment with different structural outline, and provide valuable insights into the design and application of equipment for eliminating VOCs.

A review on the adsorption of volatile organic compounds by biomass-based porous carbon (BPC) and its mechanism

A review on the adsorption of volatile organic compounds by biomass-based porous carbon (BPC) and its mechanism

Adsorption of Gaseous Organic Compounds onto PM2.5 During Air Sampling

Adsorption of Gaseous Organic Compounds onto PM2.5 During Air Sampling

Influence of group VIB metals introduced into zeolite on the adsorption performance of VOCs in cooking oil fumes

Series samples of the MEL topology zeolite containing VIB group metals (VIB-S2) were synthesized via direct hydrothermal method for adsorption of volatile organic compounds (VOCs) from cooking oil fumes. Compared with silicalite-2 (S2, 66.24 mg/g) and ZSM-11 (Al-S2, 25.98 mg/g), VIB-S2 samples showed significantly enhanced adsorption capacity of non-methane hydrocarbons (NMHC) from cooking oil fumes (103.96 mg/g for Cr-S2, 95.88 mg/g for Mo-S2, 88.68 mg/g for W-S2). VIB group metals changed the framework structure and texture characteristics of zeolite, reduced the number of defects and hydroxyl group, and increased the proportion of non-microporous structures and increased the number of adsorption sites in VIB-S2. Consequently, VIB-S2 showed excellent organophilicity, hydrophobicity and distinct VOCs adsorption behavior to S2 and Al-S2. Systematic and quantitative correlation analysis of these factors showed that the adsorption capacity of NMHC was significantly positively correlated with hydrophobicity (correlation coefficient was 0.91, significance coefficient < 0.05), which is closely related to the non-microporous structure of samples.

Interplay of adsorptive properties and dielectric reactivity of graphenes upon edge functionalization

Graphenes have unique physicochemical properties that can be engineered for pollutant adsorption and their dielectric properties can facilitate subsequent microwave regeneration. First, graphenes have the potential for high-level control of oxygen content at the edges of the material without compromising the conjugated electronic structure of the basal plane. Because the basal plane contains lightly functionalized sp2-hybridized carbon atoms while sp3-hybridized ones are on the periphery of the sheets. Edges of graphenes can be oxidized while the basal plane can still be electronically stable with conjugated π-electrons perpendicular to the graphene lattice. For this, graphenes can be oxidized to attain controlled dispersion in water without disrupting the conjugated electron network on the basal plane, which is critical for pollutant adsorption. Graphenes have sheet-like surfaces that form dynamic, porous aggregates in water and can facilitate synthetic organic compound adsorption by the complex interplay of ‘pore’ accessibility and favorable intermolecular interactions. Thus, studying the role of oxidation of graphenes can help unravel the interplay between inter-sheet distance and the adsorption of synthetic organic compounds. Second, the sp2 hybridized basal planes of graphenes have mobile π-electrons that are expedient for rapid dielectric heating, which can be harvested for rapid and efficient microwave regeneration. Fundamental research on graphene chemistry can lead to a paradigm shift in the water treatment industry towards the safe and sustainable deployment of regenerable nano-scale adsorbents. This article presents a perspective on how to approach edge functionalization of graphene with an aspiration to advance their safe and sustainable use in water treatment.

Influence of gas adsorption on surface potential of porphyrin functionalized boron doped diamond thin films

Porphyrins functionalized diamond surfaces are interesting candidates for wide variety of applications due to their remarkable physical and chemical properties. In this work, the properties of 5-(4-carboxyphenyl) triphenyl porphyrins functionalized boron-doped diamond (BDD) surface followed by gas adsorption were studied at room temperature. After structural and morphological characterizations of the bare BDD surface and porphyrins functionalized BDD surface, a scanning Kelvin probe system was used to investigate the surface potential distribution due to the adsorption of volatile organic compounds (VOCs) under visible light illumination conditions. Gas adsorption studies showed poor response in bare BDD surfaces under different gas atmospheres. On the other hand, a significant response with discriminable gas interactions was achieved in porphyrins functionalized BDD surface under visible light illumination. The obtained results suggest that visible light has influenced gas interactions because of porphyrins. The increased response (∼ 2.5 times) of metal-free porphyrin functionalized BDD thin film towards triethylamine (TEA) is accounted to the donor nature of TEA. This study helps in developing a new generation of novel conductive type diamond-based photo enhanced gas sensors at room temperature that can be utilized for fish freshness monitoring.

Melamine Network as a Solution for Significant Enhancement of the Mechanical, Adsorptive, and Surface Properties in a Novel Carbon Nanomaterial-Silica Aerogel Composite.

Silica aerogels exhibit exceptional characteristics such as mesoporosity, light weight, high surface area, and pore volume. Nevertheless, their utilization in industrial settings remains constrained due to their brittleness, moisture sensitivity, and costly synthesis procedure. Several studies have proved that adding nanofillers, such as carbon nanotubes (CNT) or graphene nanoplatelets (GNP), can improve the mechanical strength of the aerogels. The incorporation of nanofillers is often accompanied by agglomeration and pore blockage, which, in turn, deteriorates the surface area, pore volume, and low density. Including flexible melamine foam (MF) as a scaffold for the silica aerogel and nanofiller composite can prevent the restacking of the nanofillers through π-π interaction, hence maintaining the incredible properties of aerogels and improving their mechanical properties. CNT, GNP, and the polymeric silica precursor, polyvinyltrimethoxysilane (PVTMS), were added to a MF, at varying concentrations, to fabricate the MF-aerogel nanocomposites. Surfactant and sonication were utilized to ensure a homogeneous dispersion of the nanofillers in the system. The presence of MF prevented the agglomeration of nanofillers, resulting in lower density and relatively higher surface properties (SBET up to 929 m2·g-1 and pore volume up to 4.34 cc·g-1). Moreover, the MF-supported samples could endure 80% strain without breakage and showed an outstanding compressive strength of up to ∼20 MPa. These aerogel nanocomposites also demonstrated an excellent volatile organic compound (∼2680 mg·g-1) and cationic dye adsorption (∼10 mg·g-1).

Shaped binderless high SiO2/Al2O3 ratio Beta/ZSM-5 composites for volatile organic compounds adsorption

Shaped binderless high SiO2/Al2O3 ratio Beta/ZSM-5 composites for volatile organic compounds adsorption

Fluorination modification enhanced the water resistance of Universitetet i Oslo-67 for multiple volatile organic compounds adsorption under high humidity conditions: Mechanism study

The construction of metal–organic frameworks (MOFs) with highly efficient capture for volatile organic compounds (VOCs) adsorption under humid conditions is a significant yet formidable task. Herein, series of fluorinated UiO-67 modified with trifluoroacetic acid (TFA) and 4-fluorobenzoic acid were successfully synthesized for VOCs adsorption under high humidity conditions. Experiments results showed that UiO-67 modified with 4-fluorobenzoic acid (67-F) presented excellent adsorption capacity of 345 mg/g for toluene adsorption and exhibited great water resistance (10.0 vol% H2O, 374 mg/g toluene adsorption capacity). Characterization results indicated that the introduction of 4-fluorobenzoic acid induced the competitive coordination between 4-fluorobenzoic acid and 4,4-biphenyl dicarboxylic acid (BPDC) with Zr4+, causing the formation of abundant defects to provide extra adsorption sites. Meanwhile, the benzene ring in 4-fluorobenzoic acid enhanced the π-π conjugation, causing the further promotion of VOCs adsorption capacity. More importantly, the water resistance mechanism was investigated and elucidated that the introduction of F decreased the surface energy of 67-F and its affinity with water. Meanwhile, the metal complex induced by the fluorinated modification produced an electron-dense pore environment, which greatly improved its chemical and water stability. This work provided a strategy for preparing an adsorbent with high water resistance for real-world VOCs adsorption at high humidity conditions.