Adsorption Of Cyclohexane Research Articles

Investigating the Dynamics of a Soft Crystalline Covalent Organic Framework during Benzene and Cyclohexane Adsorption by in situ Powder X‐ray Diffraction

Due to their similar boiling points, separation of benzene and cyclohexane mixtures is among the current challenging processes faced by the petrochemical industry. As recently assessed, the soft imine‐based covalent organic framework [(TAM)(BDA)2] (COF‐300; TAM = tetrakis(4‐aminophenyl)methane, BDA = terephthaldehyde) possesses higher affinity for benzene than cyclohexane in both static conditions at 298 K and dynamic conditions in the range of 298–348 K. As shown in this contribution, in situ powder X‐ray diffraction while dosing benzene and cyclohexane vapors in the range of 0.01–4.74 bar on the narrow‐pore form of COF‐300 confirmed the coherent switchability of its framework, unveiling the progressive formation of different intermediate‐ and large‐pore forms. In addition, a basket of otherwise inaccessible key crystallochemical details—“on/off” structural‐feature changes cooperating to adsorption, primary adsorption sites, and host–guest and guest–guest interactions—was successfully retrieved. Overall, these findings allowed to shed light on the framework dynamics underneath the previously observed selectivity toward benzene over cyclohexane, completing this case of study and providing relevant information for the design of new‐generation adsorbents for this applicative context.

Effective Adsorption of Cyclohexene and Analytically Perfect Separation of Cyclohexene/Cyclohexanol Azeotropes by Nonporous Adaptive Crystals of a Hybrid[3]arene

Effective Adsorption of Cyclohexene and Analytically Perfect Separation of Cyclohexene/Cyclohexanol Azeotropes by Nonporous Adaptive Crystals of a Hybrid[3]arene

Molecular Simulation of Cyclohexane in Nanoporous Materials: Adsorption of Conformers and Coadsorption with Water and Carbon Dioxide.

Molecular simulation is used to investigate the adsorption of an organic molecule and its different conformers into various nanoporous adsorbents. In more detail, we perform grand canonical Monte Carlo simulations to determine the adsorption isotherms for cyclohexane with its three conformers (chair, boat, and twisted boat) at three different temperatures into a molecular model of active carbons and two metal-organic frameworks (MOFs) (Cu-BTC and Al-Fum). By considering the adsorption of each conformer separately, we show that the adsorption isotherms are weakly dependent on the molecular conformation. When considering the concomitant adsorption of the three conformers under realistic conditions (to verify the population of each conformer in bulk mixtures), we show that the chair conformer is predominantly adsorbed in each material. However, such favorable adsorption mostly reflects the fact that this conformer has the largest population in the bulk mixture under the same thermodynamic conditions. On the contrary, with an increase in the cyclohexane gas pressure, the adsorption of boat and twisted boat conformers increases, while that of the chair conformer decreases as packing (entropy) effects become predominant during confinement. The adsorption of cyclohexane in the active carbon and MOF materials is also considered in the presence of water and CO2 atmospheres. In the case of the Al-fumarate material, the material is found to be strongly organophilic so that water and CO2 adsorption are negligible, and cyclohexane adsorption is not affected by competitive adsorption under any considered thermodynamic condition. On the contrary, for the active carbon and Cu-BTC material, competitive adsorption between cyclohexane and water or CO2 is observed even if cyclohexane adsorption remains preferred. While the different molecules coexist in the adsorbed phase at low pressures, increasing the cyclohexane pressure beyond 103 Pa promotes cyclohexane adsorption concomitantly with water and/or CO2 desorption.

Insights into the Synergistic Catalytic Effect of TiO2 Supported V-W Oxides for Selective C-H Bond Oxidation of Cyclohexane to KA Oil.

It is urgent to develop an efficient and stable non-noble metal catalyst for selective C-H bond oxidation of cyclohexane. Herein, a series of V-W oxides supported on TiO2catalysts (V-W/TiO2) were fabricated. The V-W/TiO2catalysts exhibited much higher catalytic activity for the selective oxidation of cyclohexane to KA oil, compared to that of V/TiO2and W/TiO2catalysts. The good distribution of active metals and the synergistic effect were responsible for the enhanced catalytic activity. H2-TPR results disclosed that the presence of V inV-W/TiO2 affected the reducibility of W6+species, and XPS verified that an electronic interaction was formed between them. Such results led to good catalytic reusability of V-W/TiO2catalyst during the reactions, and no obvious activity loss was found after six runs. The reaction mechanism was investigated, and the results verified that hydroxyl radicals generated from H2O2homolysis were the main active oxidative species. Theoretical study revealed that V dopant could regulate electronic structure of adjacent O atom, facilitating the adsorption of cyclohexane, and lower energy was needed for the rate-limiting step over V-W/TiO2during the whole oxidation reaction. This work developed an efficient V-W/TiO2catalyst for the selective oxidation of cyclohexane via a synergistic effect.

Highly selective aerobic oxidation of cyclohexane by flower-like MoO3-x microspheres-nitrogen-doped carbon dots heterojunction

Due to the higher susceptibility of alcohols and ketones to oxidation compared to alkanes, converting inert C-H bonds in alkanes into high value-added product KA oil with high selectivity is still a significant obstacle. In this study, flower-like microspheres of MoO3-x, featuring aligned nanosheets and oxygen vacancies, were combined with nitrogen doped carbon dots (NCDs) to fabricate S-scheme heterojunctions of MoO3-x-NCDs for boosting the photocatalytic efficiency in oxidizing cyclohexane. Because of the oxygen vacancies-triggered localized surface plasmon resonance (LSPR) and the S-scheme charge transfer mechanism, there was a significant improvement in the absorption of visible light and an enhancement in the efficiency of charge separation. The MoO3-x-NCDs composites exhibited a notably improved catalytic performance in cyclohexane oxidation. The MoO3-x-NCDs composite exhibited remarkable selectivity of KA oil in catalyzing cyclohexane oxidation under light exposure, attributed to the substantial increase in cyclohexane adsorption capacity. The highest cyclohexane transformation rate of 9.98 % was achieved by MoO3-x-NCDs-2 composites with a MoO3-x/NCDs ratio of 50:1, outperforming bare MoO3-x by 1.81 times, while exhibiting a KA oil selectivity reaching 93.75 %. The mechanism of selective photocatalytic oxidation was explored using photoelectric examination, analysis of energy bands, and evaluation of active radicals. In this research, green photocatalysts were fabricated through the utilization of NCDs, enabling efficient conversion and selective oxidation of cyclohexane in gentle environments. This innovative approach holds great potential for advancing the field of photocatalysis.

Low-Temperature Selective Oxidative Dehydrogenation of Cyclohexene by Titania-Supported Nanostructured Pd, Pt, and Pt-Pd Catalytic Films.

Films of titania-supported monometallic Pd, Pt, and bimetallic Pt-Pd catalysts made of metallic nanoparticles were prepared by magnetron sputtering and studied in the oxidative dehydrogenation (ODH) of cyclohexene. Pd/TiOx and Pt-Pd/TiOx were found active at as low temperature as 150 °C and showed high catalytic activity with high conversion (up to 81%) and benzene selectivity exceeding 97% above 200 °C. In turn, the Pt/TiOx catalyst performed poorly with the onset of benzene production at 200 °C only and conversions not exceeding 5%. The activity of bimetallic Pt-Pd catalysts far exceeded all of the other investigated catalysts at temperatures below 250 °C. However, the production of benzene significantly dropped with a further temperature increase due to the enhanced combustion of CO2 at the expense of benzene formation. As in situ NAP-XPS measurement of the Pt-Pd/TiOx catalyst in the reaction conditions of the ODH of cyclohexene revealed Pd surface enrichment during the first temperature ramp, we assume that Pd surface enrichment is responsible for enhanced activity at low temperatures in the bimetallic catalyst. At the same time, the Pt constituent contributes to stronger cyclohexene adsorption and oxygen activation at elevated temperatures, leading to changes in conversion and selectivity with a drop in benzene formation and increased combustion to CO2. Both the monometallic Pd and the Pt-Pd-based catalysts produced a small amount of the second valuable product, cyclohexadiene, and below 250 °C produced only a negligible amount of CO2 (<0.2%). To summarize, Pd- and Pt-Pd-based catalysts were found to be promising candidates for highly selective low-temperature dehydrogenation of cyclic hydrocarbons that showcased reproducibility and stability after the temperature activation. Importantly, these catalysts were fabricated by utilizing proven methods suitable for large-scale production on extended surfaces.

Ru-Loaded Biphasic TiO2 Nanosheet-Tubes Enriched with Ti3+ Defects and Directionally Deficient Electrons as Highly Efficient Catalysts in Benzene Selective Hydrogenation

Crystalline phase engineering is a prominent strategy for synergistically optimizing the surface–body phases of a catalyst. In this work, TiO2 nanosheets assembled into nanotubes (TNSTs) with two phases, anatase and rutile, were firstly synthesized via crystal engineering by simple thermal annealing. These were subsequently loaded with Ru nanoparticles, with a mean size of 5.0 nm, to create the efficient benzene hydrogenation catalyst Ru/TNSTs. The well-designed nanosheet-tube structure boasts a large specific surface area and excellent transmission channels, which effectively prevents the agglomeration and deactivation of loaded Ru nanoparticles, as well as promoting the internal diffusion in the reaction process of benzene hydrogenation to cyclohexene. Furthermore, titanium dioxide nanosheet-tubes contain numerous Ti3+ defects, which not only improves the overall conversion rate of cyclohexene but also enhances the suppression of cyclohexene adsorption. Most importantly, the titanium dioxide with its two-phase composition of 75 wt% anatase and 25 wt% rutile increases the ratio of electron deficiencies of Ru and promotes cyclohexene desorption. These synergistic properties enhance the selectivity and efficiency of the Ru/TNSTs catalysts, resulting in excellent performance in the hydrogenation of benzene to cyclohexene. In particular, the Ru/TNSTs-4 catalyst (annealed for 4 h), under the specific conditions of 140 °C temperature and 5 MPa hydrogen pressure for the hydrogenation process, achieves a 95% initial selectivity and 51% yield of cyclohexene in the reaction, outperforming most supported Ru-based catalysts. This work may provide new perspectives for designing efficient benzene hydrogenation catalysts via crystalline phase engineering.

Effect of Ligand Aromaticity on Cyclohexane and Benzene Sorption in IRMOFs: A Computational Study.

A series of four isoreticular MOFs (IRMOF-1, -10, -14, and -16) were selected for a computational investigation of the effect of ligand aromaticity on the adsorption capacity of an aromatic VOC (benzene) compared to its nonaromatic analog (cyclohexane). The affinity of the adsorbates was evaluated by calculating Henry's constants and adsorption enthalpies. It has been evidenced that while KH values decrease with ligand elongation (IRMOF-10 and -16), inserting a pyrene core into the MOF structure (IRMOF-14) increases both the cyclohexane and benzene adsorption efficiency by ∼290 and 54%, respectively. To elucidate host-guest interactions, we sought to locate preferential adsorption sites in MOF structures for the two VOCs studied by using the GCMC method. It appears that benzene interacts with the metal center (Zn4O clusters) and most of the ligand while cyclohexane tends to localize preferentially only near the Zn4O clusters. Coadsorption isotherms (equimolar mixture of benzene and cyclohexane) demonstrated the preferential adsorption of cyclohexane due to the stronger affinity for the MOF structure. On the other hand, for other isoreticular structures, the ligand elongation leads to a shift of the adsorption curve of cyclohexane caused by pore size increase and therefore less interactions with the walls. This phenomenon is counterbalanced in the case of IRMOF-14 due to stronger interactions between the cyclohexane and pyrene groups. The present results thus open perspectives in the design of promising MOF candidates for high-performing separation and sorption/detection of hydrocarbon VOCs.

Fabrication of single Co sites in graphitic carbon nitride via the ion exchange to boost aerobic cyclohexane oxidation

Cyclohexane oxidation is an industrial process for manufacturing cyclohexanol, cyclohexanone and adipic acid, while it remains a huge challenge to develop highly efficient catalysts for intensifying this process. Herein, a bottom-up synthesis approach, coupling the one-pot and ion exchange strategy, is developed to fabricate atomically dispersed Co on graphitic carbon nitride (g-C3N4) for the aerobic cyclohexane oxidation. The loading of the single-atom Co on Co/g-C3N4 can be facilely tuned by adjusting the ion exchange extent of Na + on Na/g-C3N4 precursor. Comprehensive characterizations demonstrate the atomical location of Co in sixfold cavities of g-C3N4, accompanied by the electron interaction between Co atoms and g-C3N4. The resulting Co/g–C3N4–1 catalyst possesses the superior oxidation performance with the 28.8 % cyclohexane conversion and 93.0 % overall selectivity toward desired products, and it also exhibits an acceptable universality to the catalytic oxidation of various hydrocarbons. The mechanism study revealed that besides the dissociation of O2 molecules on single-atom Co sites, the electron-rich g-C3N4 surface stemming from atomic Co doping facilitated the cyclohexane adsorption, which synergically boosted the subsequent oxidation reaction following the surface catalytic mechanism. We anticipate that such a concept of fabricating atomically dispersed metals via the ion exchange strategy provides a novel insight and feasible approach for the design of highly efficient single-atom catalysts for the cyclohexane oxidation and beyond.

Adsorption properties of hollow carbon spheres to gaseous cyclohexane using DFT simulation and experiments.

The cyclohexane is the common toxic volatiles emitted from the various industry in worldwide leading to environmental degradation and human illnesses. Hence, there is a requirement for an efficient and stable adsorbent for adsorbing these toxic molecules to safeguard human health and the air atmosphere. Hollow carbon spheres (HCS) are a new type of carbon nanomaterial with large specific surface area, low density, and good chemical and thermal stability. In this study, DFT simulations and static-dynamic adsorption studies of cyclohexane were carried out using HCS as the adsorbent material. Among them, static adsorption focuses on adsorption/desorption isotherm, adsorption isotherm model fitting and isosteric heat of adsorption. Dynamic adsorption was mainly studied the effect of initial concentrations, gas flow rate, and ambient temperature on adsorption performance. The results showed that HCS exhibited very good performance in cyclohexane adsorption.

Highly enhanced direct catalytic oxidation of cyclohexane to adipic acid with molecular oxygen: Dynamic collaboration between zeolite channel micro-environment and Au clusters

Adipic acid is a valuable chemical used to product Nylon-66, and one of the greenest ways to synthesize it is catalyzing the oxidation of cyclohexane by molecular oxygen in the absence of any other chemicals. However, it is challenging to convert cyclohexane effectively with high selectivity to adipic acid using the available catalysts. In response to the dilemma of achieving satisfactory conversion and selectivity at the same time, a remarkable Au@NaX catalyst is proposed using an improved in-situ crystallization method that exhibits Au clusters surrounded by X-zeolite channels. A 29.5% conversion of cyclohexane and an 85.6% selectivity to adipic acid can be obtained in a one-pot oxidation of cyclohexane at 140 °C, 20 bar O2, far exceeding most published results. Since determined by detailed characterizations and DFT calculations, the effective dynamic collaboration between Au clusters and zeolite inner micro-environment is the decisive role for superior catalytic performance. Specifically, the surrounding zeolite channel encourages the adsorption and activation of cyclohexane over the confined Au clusters, resulting in an unprecedented activity. The continuous oxidation of cyclohexanol and cyclohexanone to adipic acid is also vulnerable on the enclosed Au clusters, and the subsequent adipic acid can be further stabilized as a result of the strong interaction of –COOH with Na± in zeolite channels surrounding enclosed Au clusters. It prevents AA from poisoning active sites and generates a higher selectivity for the desired adipic acid. Our study highlighted the critical significance of the dynamic interaction between metal clusters and the zeolite channel microenvironment. It would shed light on the further high-performance catalysts designs for selective oxidation.

Electronic metal − support interaction directed electron-deficient nanoparticulate Ru on Ti3C2 MXene-derived TiO2 nanoflowers for robust benzene semi-hydrogenation

Regulating the geometric and electronic configurations of interfacial active sites is an attractive approach to design high-efficiency catalysts. Here, guiding by the electronic metal–support interaction (EMSI), we constructed the chemical state-tunable nanoparticulate Ru on three-dimensional (3D) porous TiO2 nanoflowers derived from 2D Ti3C2 MXene nanosheets (Ru/TMTFs-x). Benefitting by the unique geometric architecture and EMSI-directed electron-deficient configuration of Ru, the catalysts are efficient in benzene semi-hydrogenation, achieving a high turnover frequency (TOF, 7.2 s−1) and an excellent initial cyclohexene selectivity (78%) on the most electron-deficient Ru/TMTFs-773 catalyst. Despite that the TOFs are nearly identical along with the enhancement in electron-deficient degree of Ru on Ru/TMTFs-x by tuning the Ti4+: Ti3+ molar ratios, which was originated from the resemblances in Ru size and acidity, a positive correlation between cyclohexene selectivity and electron-deficient degree of Ru was recognized. By virtue of kinetics analyses and density functional theory (DFT) calculations, the promotion in net generation rate of cyclohexene and the weakening in cyclohexene adsorption on Ru/TMTFs-x when lowering the electron density of Ru are responsible for the selectivity enhancement. A linearity between selectivity and the percentage of Ti4+ sites was identified, further corroborating the EMSI-mediated selectivity enhancement on Ru/TMTFs-x.

Valorization and characterization of bio-oil from Salvadora persica seed for air pollutant adsorption.

Salvadora persica (SP) is an important medicinal plant. Numerous articles have been conducted on the leaf, the roots, and the stem of the plant, but there is little information about the seed. Thus, the present work tries to identify the chemical composition of SP seed bio-oil and investigates its use as an adsorbent for cyclohexane removal. This study extracted bio-oil from seeds using different polar and non-polar organic solvents. Two techniques have been used to determine the chemical composition of the bio-oil extracted: FTIR and GC-MS. Results show that the extracted bio-oil presented 13 new major organic bio-compounds in n-hexane and ethanol SP seed extracts. Moreover, the analytical results showed that the two extracts are complex and contained thiocyanic acid, benzene, 3-pyridine carboxaldehyde, benzyl nitrile, ethyl tridecanoate, ethyl oleate, and dodecanoic acid ethyl ester. Additionally, each technique of analysis showed that the extracted bio-oils from SP seeds are rich in non-polar compounds. Indeed, the major fatty acids obtained are pentadecylic acid, myristic acid, lauric acid, oleic acid, margaric acid, and tricosanoic acid. This work provides guidelines for identifying these compounds, among others, and offers a platform for using SP seeds as a herbal alternative for various chemical, industrial, and medical applications. Furthermore, the capacity of SP extracts for air pollution treatment, namely, the removal of cyclohexane in batch mode, was investigated. Results showed that cyclohexane adsorption could be a chemical process involving both monolayer and multilayer adsorption mechanisms. The pores and the grooves on the surface of the SP bio-oil extract helped in adsorbing the cyclohexane with an outstanding maximum removal capacity of about 674.23mg/g and 735.75mg/g, respectively, for the ethanol and hexane SP extracts, which is superior to many other recent adsorbents.

Control of the pore chemistry in metal-organic frameworks for efficient adsorption of benzene and separation of benzene/cyclohexane

Control of the pore chemistry in metal-organic frameworks for efficient adsorption of benzene and separation of benzene/cyclohexane

Surface chemistry and photochemistry of cyclohexane on rutile TiO2(110)

Cyclohexane is a high-valued chemical rece1vmg significant interest in liquid hydrogen storage technology. TiO2-based catalysts show high performance in the photocatalytic dehydrogenation of cyclohexane under mild conditions, but the detailed reaction mechanism is not well understood. With the surface science approaches, we have studied the adsorption and surface chemistry of cyclohexane on rutile TiO2(110). The thermal desorption spectroscopy and X-ray photoelectron spectroscopy results both demonstrate the molecular adsorption of cyclohexane on rutile TiO2(110). Upon the UV Hg light irradiation, photodesorption of cyclohexane occurs from both the chemisorbed monolayer and the multilayer. No decomposition nor dehydrogenation of cyclohexane occurs on rutile TiO2(110). These results deepen the fundamental understanding of the surface chemistry of cyclohexane on the TiO2 surface.

Efficient Catalytic Combustion of Cyclohexane over PdAg/Fe2O3 Catalysts under Low-Temperature Conditions: Establishing the Degradation Mechanism Using PTR-TOF-MS and in Situ DRIFTS.

Cyclohexane, a typical volatile organic compound (VOC), poses high risks to the environment and humans. Herein, synthesized PdAg/Fe2O3 catalysts exhibited exceptional catalytic performance for cyclohexane combustion at lower temperatures (50% mineralization temperature (T50) of 199 °C, 90% mineralization temperature (T90) of 315 °C) than Pd/Fe2O3 (T50 of 262 °C, T90 of 335 °C) and Fe2O3 (T50 of 305 °C, T90 of 360 °C). In addition, PdAg/Fe2O3 displayed enhanced stability by alloying Ag with Pd. The redox and acidity of the PdAg/Fe2O3 were studied by XPS, H2-TPR, and NH3-TPD. In situ diffuse reflectance infrared Fourier transform spectroscopy and proton-transfer-reaction time-of-flight mass spectrometry were applied to identify the intermediates formed on the catalyst surface and in the tail gas during oxidation, respectively. Results suggested that loading PdAg onto Fe2O3 significantly enhanced the adsorption and activation of oxygen and cyclohexane, oxidative dehydrogenation of cyclohexane to benzene, and catalytic cracking of cyclohexane to olefins at low temperatures. This in-depth study will benefit the design and application of efficient catalysts for the effective combustion of VOCs at low temperatures.

Atomically dispersed Co/C3N4 for boosting aerobic cyclohexane oxidation

The atomically-dispersed and high-loading Co on graphitic carbon nitrogen (Co/C3N4-w, w representing the molar ratio of Co to melamine in the synthesis recipe) was synthesized by coupling the one-pot strategy with the electrostatic adsorption method and used for the solvent-free aerobic oxidation of cyclohexane. The characterization results of Co/C3N4-w revealed that the single-atom Co with the positive charge existed in the sixfold cavities of C3N4 and was stabilized by the CoN interaction along with the electron transfer from Co atoms to C3N4. The catalytic activity of Co/C3N4-w presented the positive correlation with the loading of the single-atom Co, and the superior catalytic performance with 21 % conversion and 95 % overall selectivity was obtained over Co/C3N4-0.02, which also exhibited the excellent universality to the aerobic oxidation of other cycloalkanes and alkyl aromatics. Experiments combined with density functional theory calculations demonstrated that the favored O2 dissociation and intermediate cyclohexylhydroperoxide decomposition on the low-coordinated single-atom Co, and the promoted adsorption of cyclohexane on the electron-rich C3N4 surface, synergically boosted the cyclohexane oxidation. Distinctively, the high stability of Co/C3N4-0.02 in the cyclohexane oxidation originated from the robust single-atom Co structures and hydrophobic C3N4 surface.

Cyclohexane and n-hexane adsorption studies on novel hex-star antimonene nanosheets – A first-principles outlook

• The geometrically stable hex-star antimonene nanosheets possesses an energy band gap of 0.862 eV. • Cyclohexane and n-hexane molecules are adsorbed on hex-star antimonene nanosheet. • Both cyclohexane and n-hexane are physisorbed on hex-star antimonene. • Hex-star antimonene nanosheets exhibits chemi-resistive nature upon adsorption of cyclohexane and n-hexane. The presence of acetic acid, nitrates, vat dyes, and heavy metals all collectively produce highly toxic effluent from the textile industry. The aliphatic hydrocarbons, namely cyclohexane, and n-hexane are the common toxic volatiles emitted from the various textile industry in worldwide leading to environmental degradation and human illnesses. Hence, there is a requirement for high sensitivity and a stable chemical sensor for detecting these toxic molecules to safeguard human health and the air atmosphere. In this research, we used hex-star antimonene as a leading sensing material to detect cyclohexane and n-hexane molecules at ambient temperature. Originally, the structural firmness of hex-star antimonene is validated with the influence of cohesive formation energy. Furthermore, the band structure and projected density of states spectrum provides the fingerprint for electronic properties of hex-star antimonene. The band gap of hex-star antimonene is calculated to be 0.862 eV. Significantly, the adsorption properties of cyclohexane and n-hexane on the base substrate are investigated by the deciding factors, such as Bader charge transfer, adsorption energy, and relative band gap variations. The scope of adsorption energy (−0.115 eV to −0.502 eV) confirms that both cyclohexane and n-hexane are physisorbed on hex-star antimonene. The outcome recommended that hex-star antimonene can be utilised as a chemical sensor to monitor the cyclohexane and n-hexane emitted from textile industries.

Mesoporous SiO2 decorated superhydrophobic fabric evaporator with selective oil removal and Rh B photodegradation performance

Solar steam generation devices assembled based on interfacial heating technology show the ability to produce clean water, while it faces challenges in the sewage environments. The superhydrophobic fabric was used to selectively adsorb surface oily pollutants based on its non-wettability. Soluble pollutants remaining in water after evaporator treatment can be further removed through photodegradation. Herein, the device composed of superhydrophobic C3N4/Bi2MoO6 heterojunction, water supply layer and CuO photothermal layer was assembled to remove oily and water-soluble pollutants and produce clean water. The contact angle of water on the superhydrophobic C3N4/Bi2MoO6 surface reaches 154° and shows the selective adsorption of cyclohexane. The prepared bulk catalyst C3N4/Bi2MoO6 not only indicate the stability of reuse, but also maintained the degradation efficiency of 98.7% under outdoor light conditions. Through the active species capture experiments, •O2− was verified as the main active material in the photodegradation process. The formation of Type II heterojunctions between C3N4 and Bi2MoO6 facilitated the separation of e−/h+ at the C3N4/Bi2MoO6 interface.

Impact of Pore Flexibility in Imine-Linked Covalent Organic Frameworks on Benzene and Cyclohexane Adsorption.

This work focuses on the impact of covalent organic frameworks' (COFs) pore flexibility in the adsorption and separation of benzene and cyclohexane. With this aim, we have selected the imine-linked 3D COFs COF-300 and LZU-111 as examples of flexible and rigid frameworks, respectively. Optimized syntheses at room temperature or in solvothermal conditions enabled us to selectively isolate the narrow-pore form of COF-300 (COF-300-rt) or a mixture of the narrow-pore and a larger-pore form (COF-300-st), respectively, with different textural properties (BET specific surface area = 39 or 1270 m2/g, respectively, from N2 adsorption at 77 K). In the case of LZU-111, only the room temperature route was successful, leading to the known microporous framework. COF-300-rt, COF-300-st, and LZU-111 were studied for benzene and cyclohexane adsorption and separation in static and dynamic conditions. At 298 K and 1 bar, these COFs adsorb more benzene (251, 221, and 214 cm3/g STP, respectively) than cyclohexane (175, 133, and 164 cm3/g STP, respectively). Moreover, the benzene and cyclohexane isotherms of COF-300-rt and COF-300-st are characterized by steps, as expected with a flexible material. Indeed, in situ powder X-ray diffraction experiments on benzene- and cyclohexane-impregnated batches enabled us to trap, for the first time, a sequence of forms of COF-300 with different pore aperture, rationalizing the stepped hysteretic isotherms. Finally, benzene/cyclohexane separation was evaluated using a benzene/cyclohexane 50:50 v/v flow at different temperatures (T = 298, 323, and 348 K): LZU-111 does not selectively retain any of the two components, while COF-300 exhibits stronger benzene-COF interactions also in dynamic conditions.