Trimethylbenzene Research Articles

Seasonal variability of volatile organic compounds (VOCs) at a high-altitude station in the Western Ghats, India: Influence of biogenic, anthropogenic emissions and long-range transport

Seasonal variability of volatile organic compounds (VOCs) was studied using year-long observations (June 2019–May 2020) over a high-altitude (1380m AMSL) forested site in the Western Ghats of India. Isoprene, a well-known biogenic VOC, peaked during pre-monsoon. Temperature stress and higher photo synthetically active radiation (PAR) were the drivers behind isoprene emissions from the surrounding forested regions. The daytime average isoprene mixing ratio was 1.92 ± 1.51 ppb during summer and the night time average was 0.02 ± 0.01 ppb. A strong relationship between isoprene mixing ratio and ambient temperature was derived. Most of the anthropogenic VOCs like acetonitrile, benzene, toluene and xylene were found to be higher during winter. These anthropogenic VOCs mostly exhibited afternoon to evening peaks, which suggests the contribution by traffic emissions along with other combustion sources (biofuels) and vertical updraft of pollutants from the surrounding valley region. The toluene to benzene ratio (T/B) was >1 during the afternoon and evening hours in monsoon, whereas, aged air masses with lower T/B ratios (<0.7) prevailed during other seasons. Polar bi-variate plots reveal that toluene, xylene and tri-methyl benzene (TMB) were mostly emitted at the south-west of the measurement site, irrespective of the season, indicating a dominant local traffic related source throughout the year. The contribution of local emissions and regional background on two selected aromatic VOCs, toluene and xylene was estimated, revealing the dominance of local anthropogenic sources during monsoon and post monsoon. Positive matrix factorization revealed three source factors in all the seasons with one additional factor during winter and pre-monsoon. The first factor was constituted of toluene, benzene, xylene and TMB, and the T/B ratio was ∼1.2, indicating traffic/fossil fuel contribution. A second ‘biomass burning’ factor was dominated by acetonitrile, ethanal, acetone, and benzene in which the T/B ratio was 0.45. Factors one & two were further validated by comparison with chamber experiments conducted using different combustion sources and solvents. The third factor was dominated by isoprene and monoterpenes which were attributed to biogenic emissions. The fourth factor comprised mainly of acetonitrile, ethanal, and acetone indicating aged air masses due to long-range transport with contributions from photochemical production and biomass burning.

Understanding the Impact of Fuel on Surfactant Microstructure of Firefighting Foam

Aqueous film-forming foam is being phased out due to the environmental impacts of fluorinated surfactants contained in the firefighting foams. To develop an environmentally friendly firefighting foam, it is important to understand the factors controlling the firefighting performance of surfactants. Fuel transport through foam has been considered as a dominant mechanism for foam collapse. Therefore, the impact of fuels (heptane, octane and trimethylbenzene (TMB)) on surfactant microstructure was studied for three different types of surfactants (Capstone, Glucopon, and siloxane) that have applications in firefighting foam. Multiple techniques were used to identify the microstructure and interfacial properties of surfactants with and without exposure to liquid fuel. The ignition time of fuel vapor through foam and solubility of fuel through liquid surfactant solution were measured as well. This work shows fuel solubility has an impact on the surfactant microstructure and interfacial properties. In addition, fuel solubility and vapor pressure affect the ignition time of fuel vapors.

Enhanced properties of a positive-charged nanofiltration membrane containing quaternarized chitosan through second interfacial polymerization for the removal of salts and pharmaceuticals.

Nanofiltration (NF) membrane technology has been widely used in the removal of salts and trace organic pollutants, such as pharmaceuticals and personal care products (PPCPs), due to its superiority. A positive-charged composite NF membrane with an active skin layer was prepared by polyethyleneimine (PEI), trimethyl benzene chloride, and quaternate chitosan (HTCC) through second interfacial polymerization on the polyethersulfone ultrafiltration membrane. The physicochemical properties of the nanocomposite membrane were investigated using surface morphology, hydrophilicity, surface charge, and molecular weight cut-off (MWCO). The influence of the concentration and reaction time of PEI and HTCC was documented. The optimized membrane had a MWCO of about 481 Da and possessed a pure water permeability of 25.37 L·m-2·h-1·MPa-1. The results also exhibited salt rejection ability as MgCl2 > CaCl2 > MgSO4 > Na2SO4 > NaCl > KCl, showing a positive charge on the fabricated membrane. In addition, the membrane had higher rejection to atenolol, carbamazepine, amlodipine, and ibuprofen at 89.46, 86.02, 90.12, and 77.21%, respectively. Moreover, the anti-fouling performance and stability of the NF membrane were also improved.

Efficient green Cr(VI) adsorbent from sorghum waste: Eco-designed functionalized mesoporous silica FDU-12

This paper presents an eco-design approach to the synthesis of a highly efficient Cr(VI) adsorbent, utilizing a positively charged surface mesoporous FDU-12 material (designated as MI-Cl-FDU-12) for the first time. The MI-Cl-FDU-12 anion-exchange adsorbent was synthesized via a facile one-pot synthesis approach using sodium silicate extracted from sorghum waste as a green silica source, 1-methyl-3-(triethoxysilylpropyl) imidazolium chloride as a functionalization agent, triblock copolymer F127 as a templating or pore-directing agent, trimethyl benzene as a swelling agent, KCl as an additive, and water as a solvent. The synthesis method offers a sustainable and environmentally friendly approach to the production of a so-called “green” adsorbent with a bimodal micro-/mesoporous structure and a high surface area comparable with the previous reports regarding FDU-12 synthesis. MI-Cl-FDU-12 was applied as an anion exchanger for the adsorption of toxic Cr(VI) oxyanions from aqueous media and various kinetic and isotherm models were fitted to experimental data to propose the adsorption behavior of Cr(VI) on the adsorbent. Langmuir model revealed the best fit to the experimental data at four different temperatures, indicating a homogeneous surface site affinity. The theoretical maximum adsorption capacities of the adsorbent were found to be 363.5, 385.5, 409.0, and 416.9 mg g−1 at 298, 303, 308, and 313 K, respectively; at optimal conditions (pH=2, adsorbent dose=3.0 mg, and contact time of 30 min), surpassing that of most previously reported Cr(VI) adsorbents in the literature. A regeneration study revealed that this adsorbent possesses outstanding performance even after six consecutive recycling.

Study of secondary organic aerosol formation and aging using ambient air in an oxidation flow reactor during high pollution events over Delhi

Secondary aerosols constitute a significant fraction of atmospheric aerosols, yet our understanding of their formation mechanism and fate is very limited. In this work, the secondary organic aerosol (SOA) formation and aging of ambient air of Delhi are studied using a potential aerosol mass (PAM) reactor, an oxidation flow reactor (OFR), coupled with aerosol chemical speciation monitor (ACSM), proton transfer reaction time of flight mass spectrometer (PTR-ToF-MS), and scanning mobility particle sizer with counter (SMPS + C). The setup mimics atmospheric aging of up to several days with the generation of OH radicals. Variations in primary volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs) as a function of photochemical age were investigated. Primary VOCs such as benzene, toluene, xylene, trimethyl benzene, etc. decrease and OVOCs like formic acid, formaldehyde, acetone, ethanol, etc. increase substantially upon oxidation in OFR. The highest organic aerosol (OA) enhancement was observed for the 4.2 equivalent photochemical days of aging i.e., 1.84 times the ambient concentration, and net OA loss was observed at very high OH exposure, typically after 8.4 days of photochemical aging due to heterogeneous oxidation followed by fragmentation/evaporation. In ambient air, OA enhancement is highest during nighttime due to the high concentrations of precursor VOCs in the atmosphere. SMPS + C results demonstrated substantial new particle formation upon aging and decrement in preexisting aerosol mass. This is the first experimental study conducting an in-situ evaluation of potential SOA mass generated from the ambient aerosols in India.

Elimination of Drying‐Dependent Component Deviation Using a Composite Solvent Strategy Enables High‐Performance Inkjet‐Printed Organic Solar Cells with Efficiency Approaching 16%

AbstractInkjet printing (IJP) is a roll‐to‐roll (R2R) compatible fabrication method for large‐area organic solar cells (OSCs). Unlike the coating process, the films are formed through droplet leveling and merging during IJP, and the pre‐deposited droplets are partly dissolved by the subsequent droplets. Such a process yields undesired printing pattern lines, especially in large‐area printed films. This study reveals that such a temperature‐dependent “drying lines‐related” phase separation morphology has caused component variation in the organic blend films, which leads to an obvious inhomogeneity of photocurrent in the printed OSCs. Such a phenomenon is attributed to the solubility difference between organic donor and acceptor molecules in the main printing solvent. A composite solvent strategy of ortho‐dichlorobenzene (oDCB)/trimethylbenzene (TMB) and tetralin (THN) is developed to solve this problem. The introduction of THN suppresses the formation of printing drying lines during high‐temperature printing due to the preferential miscibility of acceptor in THN, leading to the efficiency improvement to 13.96% and 15.78% for the binary and ternary devices. In addition, the 1 cm2 device with a disruptive pattern gives an efficiency of 12.80% and a certificated efficiency of 12.18%.

Kinetics of Heavy Reformate Conversion to Xylenes over MCM-41 on Zeolite Beta Composite Catalyst

Commercial heavy reformate is converted over MCM-41 on zeolite beta composite catalyst to produce mixed xylenes in a fluidized-bed batch reactor. The heavy reformate feedstock contains 67.4 wt.% trimethyl benzenes (TMBs) and 31.1 wt.% methyl ethyl benzenes (MEBs). The experiments were carried out at 300, 350 and 400 °C, while the reaction times were varied between 5 and 20 s. The conversion of MEBs was more than two times the conversion of TMBs. The selectivity to xylenes was quite high (60–65 wt.%) but changed very little with reaction time or temperature. A kinetic model was developed using a five-reaction network. The product composition obtained from the estimated kinetic parameters closely matches the experimental results, which confirms the validity of the assumptions made for kinetic modeling. The trend in the apparent activation energies of the reactions was in accordance with the relative size of the reactant molecules, and the lowest activation energy was for the transalkylation of TMBs with toluene to produce xylenes.

Structure and near-infrared spectral properties of mesoporous silica for hyperspectral camouflage materials

Mesoporous silica materials were prepared via a hydrothermal method by adjusting the content of trimethylbenzene (TMB) and PEO-PPO-PEO block copolymer (F127) in mesoporous silica. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy(TEM), nitrogen adsorption–desorption analysis(BET),Fourier transform-infrared spectroscopy (FTIR) and Visible near infrared spectrophotometry (VIS-NIR). The effects of mesoporous structure on the water load capacity and near-infrared spectra were systematically then studied. The results showed that the pore size and volume of the mesoporous silica could be tuned by varying the dosage of TMB and F127. In addition, the hygroscopicity of the mesoporous silica was linearly dependent on the pore size and volume, and the as-prepared mesoporous silica had NIR spectral features similar to those of vegetation leaves. More interestingly, as the water content increased, the water absorption peak of the mesoporous silica in the NIR wavebands was closer to that of natural leaves, showing greater similarity. Finally, camouflage coatings were prepared by using the as-prepared mesoporous silica powder as a functional filler and water-borne polyurethane as an adhesive. The cosine similarity between the camouflage coating and natural leaves reached 98.49%, suggesting that the camouflage coating achieved strong similarity in simulating the reflection spectra of plant leaves, potentially providing a new approach to the design of functional fillers of camouflage materials.

Aqueous green synthesis of organic/inorganic nanohybrids with an unprecedented synergistic mechanism for enhanced near-infrared photothermal performance.

Silver sulfide (Ag2S) nanoparticles (NPs) represent one of the most popular inorganic reagents for near-infrared (NIR) photothermal therapy (PTT). However, the extensive biomedical applications of Ag2S NPs are greatly compromised by the hydrophobicity of the NPs prepared in organic solvents, their low photothermal conversion efficiency, certain surface modification-induced damage to their intrinsic properties and short circulation time. To develop a facile yet efficient green approach to overcome these shortcomings for improved properties and performance of Ag2S NPs, we report herein the construction of Ag2S@polydopamine (PDA) nanohybrids via a "one-pot" organic-inorganic hybridization strategy, which produces uniform Ag2S@PDA nanohybrids with well-modulated sizes in the range of 100-300 nm via the self-polymerization of dopamine (DA) and subsequent synergistic assembly of PDA with Ag2S NPs in a three-phase mixed medium containing water, ethanol and trimethylbenzene (TMB). Integration of dual photothermal moieties, i.e., Ag2S and PDA at a molecular level, endows Ag2S@PDA nanohybrids with synergistically enhanced NIR photothermal properties that are much better than those of either PDA or Ag2S NPs due to calculated combination indexes (CIs) of 0.3-0.7 between Ag2S NPs and PDA based on a modified Chou-Talalay method. Therefore, this study not only developed a facile "one-pot" green approach toward producing uniform Ag2S@PDA nanohybrids with well-modulated dimensions, but also revealed an unprecedented synergistic mechanism for organic/inorganic nanohybrids that is based on dual photothermal moieties providing enhanced near-infrared photothermal performance.

Case study on the impact of the source of metabolism parameters in next generation physiologically based pharmacokinetic models: Implications for occupational exposures to trimethylbenzenes

Physiologically based pharmacokinetic (PBPK) models are a means of making important linkages between exposure assessment and in vitro toxicity. A key constraint on rapid application of PBPK models in risk assessment is traditional reliance on substance-specific in vivo toxicokinetic data to evaluate model quality. Bounding conditions, in silico, in vitro, and chemical read-across approaches have been proposed as alternative sources for metabolic clearance estimates. A case study to test consistency of predictive ability across these approaches was conducted using trimethylbenzenes (TMB) as prototype chemicals. Substantial concordance was found among TMB isomers with respect to accuracy (or inaccuracy) of approaches to estimating metabolism; for example, the bounding conditions never reproduced the human in vivo toxicokinetic data within two-fold. Using only approaches that gave acceptable prediction of in vivo toxicokinetics for the source compound (1,2,4-TMB) substantially narrowed the range of plausible internal doses for a given external dose for occupational, emergency response, and environmental/community health risk assessment scenarios for TMB isomers. Thus, risk assessments developed using the target compound models with a constrained subset of metabolism estimates (determined for source chemical models) can be used with greater confidence that internal dosimetry will be estimated with accuracy sufficient for the purpose at hand.

Molecular dynamics simulation of thermophysical properties of binary RP-3 surrogate fuel mixtures containing trimethylbenzene, n-decane, and n-dodecane

• Binary RP-3 surrogate fuel mixtures containing trimethylbenzene (TMB), n-decane, and n-dodecane are investigated via EMD simulations. • TraPPE-UA force field can appropriately describe the densities and thermal conductivities of TMB and the mixtures. • Variation ranges of the bond angles become broader and n-decanes shrink with the increasing of the temperature. • Analysis of RDFs and the ADFs are carried out. Trimethylbenzene (TMB), n-decane, n-dodecane and their mixtures are commonly used in surrogate fuel of aviation kerosene. To date, molecular dynamic studies on the thermophysical properties of TMB and their mixtures are very few. In this study, equilibrium molecular dynamics (EMD) simulations with the TraPPE-UA force field are carried out to simulate the densities and thermal conductivities of Rocket Propellant-3 (RP-3) aviation kerosene surrogate mixtures, C 10 + 1,2,4-TMB and C 10 + C 12 , under sub/supercritical pressure. Results show that the simulated densities and thermal conductivities of TMB and the mixtures are in good agreement with the NIST data, and the two surrogate models can provide reasonable surrogate accuracy in predicting the thermophysical properties of aviation kerosene RP-3. The analysis of radial distribution functions, angular distribution functions, end-end length and dihedral angle distributions is carried out to better understand the temperature effect on the structure and thermophysical properties of the surrogates. It is found that the n-decane chains become shrinking and more twisted with the increasing of the temperature which reduce the thermal conductivity of the surrogates. This research offers a good reference for the analysis thermophysical properties of n-alkanes and TMB-based fuels.

Atmospheric pressure photoionization – High-field asymmetric ion mobility spectrometry (APPI-FAIMS) studies for on-site monitoring of aromatic volatile organic compounds (VOCs) in groundwater

A continuously operating system for monitoring groundwater contamination by aromatic VOCs has been developed. For this purpose, a novel gas-water separation unit was to be used in combination with APPI-FAIMS. The gas-water separation unit successfully reduced the humidity in the sample flow to ≤1.6 ppmv prior to analyte ionization. Initially, toluene was selected as a model aromatic VOC. The quantitative response of toluene, as a single VOC in water (LOD <1 mg L−1), was used to investigate the feasibility of the monitoring system and the effect of humidity on the signal produced by the APPI-FAIMS. With humidity increase (up to 400 ppmv) an increase of the toluene signal for about 30% was observed, including the possible formation and detection of water clusters and toluene-water clusters. Similar effects were noted in the case of benzene. However, for the detection of single contaminants such as indane and trimethylbenzenes (TMBs) this was not observed even at relative high humidity (500 ppmv). Additionally, on-site, continuous, groundwater monitoring of the aromatic VOCs contamination was carried out successfully with the gas-water separation APPI-FAIMS at low humidity (0.3–1.6 ppmv) allowing simplified monitoring of a specific, total aromatic VOCs signal in groundwater.

Progress of Methylation of C6-8~Arene with Methanol: Mechanism, Catalysts, Kinetic/Thermodynamics and Perspectives

High-efficiency production of xylene/trimethylbenzene from benzene/toluene with methanol is a potential way to promote the implementation on the coupled cycle development strategy of petrochemical and coal chemical industry and optimize the resource structure. At the same time, relying on the innovation of catalytic new materials, physical chemistry, intelligent capture technology, process engineering, and other principles and methods, p-xylene (PX) and trimethylbenzene (TMB) with higher added value were prepared by C6-8~arene methylation, which could elevate the level of methylation field and improve the competitiveness of the industry. This paper focuses on the one-step methylation reaction of benzene with methanol or toluene with methanol to obtain high-purity p-xylene (BM-PX/TM-PX), and the one-step methylation reaction of xylene with methanol to obtain mesitylene (XM-TMB). The methylation reaction mechanism and the preparation strategy of a high-performance catalyst were reviewed. The high selectivity of PX obtained by precisely controlling the pore size and acid site distribution of zeolites was emphasized. Meanwhile, the current research progress of TMB, the kinetic/thermodynamics of the BM-PX/TM-PX, and XM-TMB methylation reaction were described. Based on a literature research and the conclusion of our research group, the mechanism of methylation reaction process was expounded. Finally, the new research direction of catalysts used and reaction process in methylation reaction were prospected in order to guide the rapid development of this field.

Thermodynamics of translational and rotational dynamics of C9 hydrocarbons in the pores of zeolite-beta

There has been a growing interest in the separation of aromatic hydrocarbon molecules from the petroleum stream using zeolite-based technologies. This led to numerous experimental and molecular simulation studies of the structural and dynamical properties of aromatic hydrocarbons under the confinement of microporous materials like zeolites. The understanding of the behavior of the isomers of the trimethylbenzene under confinement is crucial for their separation and purification from industrial streams. Here, we investigate the translational and rotational dynamics and associated thermodynamics of three isomers of trimethyl benzene, namely, 1,2,3-trimethyl benzene (1,2,3-TMB), 1,2,4-trimethyl benzene (1,2,4-TMB), and 1,3,5-trimethylbenzene (1,3,5-TMB) under the confinement of zeolite-beta (BEA) using molecular dynamics (MD) simulations. The trends in the diffusion coefficients of the TMB isomers calculated from our MD simulation data are in good agreement with the data already available in the literature. Analysis of dynamics and associated thermodynamic properties indicate that 1,2,4-TMB is translationally more facile than the other two isomers. The rotational motion of TMB isomers is largely anisotropic and it is relatively more significant for both 1,2,4-TMB and 1,3,5-TMB. The thermodynamic properties reveal that the distinguishability in the dynamic properties among these three isomers is essentially caused by entropy. These results are not only critical to engineer the separation process of TMB isomers across the zeolite beds but also to understand the different catalytic processes such as trans-alkylation, conversion, cracking etc.

Strengthening the Intermolecular Interaction of Prototypical Semicrystalline Conjugated Polymer Enables Improved Photocurrent Generation at the Heterojunction.

The intra and intermolecular interactions (J- and H-type aggregation) in the conjugated polymer films are found to readily facilitate the electron and hole transport, respectively. However, how those different aggregation types influence the photocurrent generation at the heterojunction is still mysterious, especially for the newly developed semicrystalline conjugated polymers. Here, the prototypical copolymer PM6 is used to tune the relative content of aggregation types with various halogen-free processing solvents. Various measurements reveal that the toluene-processed PM6 film exhibits the increased H-aggregates and crystallinity in the π-π stacking direction compared to its o-xylene- and trimethylbenzene (TMB)-processed counterparts. This is partly resulted from the weak steric effect and good solubility in the PM6 solution prepared with toluene, which strengthens the intermolecular interaction of adjacent polymer segments. After analyzing the photovoltaic properties of PM6/Y6 bilayer devices, the faster charge carrier transport, smaller charge recombination, lower energy losses, and interfacial energetic disorder can be observed in the toluene-processed device, leading to the synergistically improved short-circuit current density (JSC ) and open-circuit voltage (VOC ). These findings indicate the control of the molecular packing structure in terms of aggregation types is a powerful strategy to promote the photocurrent generation process at the conjugated polymer-based heterojunction.

Hollow mesoporous silica nanoparticles: Effective silica etching using tri-di- and mono-valent cations

Among different hollow nanostructures, the preparation of hollow mesoporous silica nanoparticles (HMSNs) is still a hotspot research field due to their unique properties e.g., large pore sizes and volumes, high drug loading capacity, ease of surface modification, large surface area, and biodegradability. Herein, novel uniform HMSNs are prepared for the first time by a combination of heterogeneous oil-water biphase stratification and simple mono-, di-, and tri-valent etching reactions. The biphase stratification reaction allows self-assembly of reactants at the oil−water interface, while the subsequent step is designed for the efficient selective silica etching under mild conditions. We have studied the effect of cation's valence (NH4+, Ca2+, and Al3+) on the silica etching reaction coupled with the biphase stratification reaction both in the absence and presence of the auxiliary pore expanded agent 1, 3, 5 trimethylbenzene (TMB). In the absence of TMB, the Brunauer–Emmett–Teller (BET) analysis confirms that Al3+ creates materials with the largest pore size (18.0 nm), whereas the use of NH4+ results in the largest pore volume (2.30 cm3/g). The pores generated using Ca2+ and Al3+ as silica etching agents have a volume 2.01 cm3/g and 2.05 cm3/g, respectively. Similar experiments in the presence of TMB leads to the formation of HMSN with larger pore sizes (24 nm and 21.5 nm) and volumes (2.70 cm3/g and 2.12 cm3/g) when using Al3+ and Ca2+, respectively, as etching agents. Drug loading capacity using Langmuir adsorption model indicate our hollow MSN material exhibit the high adsorbing DOX up to 558.23 mg per gram of nanoparticles in pH of 7.2. Furthermore, synthetized NPs exhibited high loading capacity for large protein and biomolecules such as BSA. Our findings confirmed that the charge density of cation has a critical role on selective silica etching in the preparation of HMSNs.

Novel polymer donors based on simple A1-π-A2 structure for non-halogen solvent-processed organic solar cells

Two low band gap conjugated polymers based on acceptor1-π-acceptor2 (A1-π-A2) and donor-π-acceptor (D-π-A) type architecture were synthesized for organic solar cells. The novel A1-π-A2 type polymer contains a fluorine substituted benzotriazole (FTAZ) as acceptor1 block unit (A1), tetrazine (TTz) as acceptor2 unit (A2), and thiophene as the π-bridge, namely PBTZ-TTz. The compared D-π-A type polymer contains a benzodithiophene (BDT) as rich electronic unit, TTz as electron-deficient unit and thiophene as the π-bridge, namely PBDT-TTz. Although mounting more thiophene π bridge units for better solubility and backbone geometry, the novel “A1-π-A2” type copolymer PBTZ-TTz achieved a deep HOMO energy level of −5.55 eV, just slightly higher than that of D-π-A type polymer PBDT-TTz. Moreover, the polymer PBTZ-TTz obtained a wider and stronger UV–vis absorption, better coplanarity and π-π stacking than PBDT-TTz. After processed by non-halogen solvent 1,2,4- trimethylbenzene (TMB), the PBTZ-TTz:IT-4F based device achieved a decent open circuit voltage (Voc) of 0.88 V, a lower power conversion efficiency (PCE) of 5.9%, while PBDT-TTz based device reached the PCE of 7.4% with Voc of 0.95 V. The unexpected lower PCE of PBTZ-TTz:IT-4F device is mainly due to the holes cannot transfer efficiently from acceptor to donor, the lower external quantum efficiency (EQE) spectra responding, as well as the poor phase separation morphology of the blend film. It is worth noting that both the Voc achieved are in outstanding high levels among IT-4F based devices. These results reveal that the A1-π-A2 type copolymers can enrich non-halogen solvent-processed donor materials through simple synthesis, which is beneficial for future environmentally friendly processing.

Synthesis and characterization of immobilized glucoamylase on mesocellular foams through spectroscopic techniques and catalytic activity of immobilized enzyme

Siliceous mesocellular foam (MCF) is versatile support material for enzyme immobilization. This material is attractive for its robust, well-defined pore structure with interconnected, ultra large pores that facilitate diffusion. Excellent activity and extremely low level of leaching (metal or enzyme) were attained with these robust supports. MCF was synthesized by hydrothermal procedure using tetraethylorthosilicate (TEOS), amphiphilic block co-polymers Pluronic P123 and Trimethyl benzene as auxilary chemical under acidic conditions. The amino groups have been grafted to as-synthesized mesoporous silica by 3-aminopropyl trimethoxysilane (3-APTS) and glutaraldehyde was then coupled with amino functionalized silica. The physicochemical properties of the prepared materials were characterized by Nitrogen adsorption – desorption, FTIR, XPS, CPMAS NMR techniques. Meso cellular foams having ultra large pore diameter of 241 Å. Results showed that glutaraldehyde bound silica showed highest stability for enzyme binding.

Fabrication of silica/PVA-co-PE nanofiber membrane for oil/water separation

High efficiency and anti-pollution oil/water separation membrane has been widely explored and researched. There are a large number of hydroxyl groups on the surface of silica, which has good wettability and can be used for oil-water separation membranes. Hydrophilic silica nanostructures with different morphologies were synthesized by changing templates and contents of trimethylbenzene (TMB). Here, silica nanospheres with radical pores, hollow silica nanospheres and worm-like silica nanotubes were separately sprayed on the PVA-co-PE nanofiber membrane (PM). The abundance of hydroxyl groups and porous structures on PM surfaces enabled the absorption of silica nanospheres through hydrogen bonds. Compared with different silica nanostructures, it was found that the silica/PM exhibited excellent super-hydrophilicity in air and underwater “oil-hating” properties. The PM was mass-produced in our lab through melt-extrusion-phase-separation technique. Therefore, the obtained membranes not only have excellent underwater superoleophobicity but also have a low-cost production. The prepared silica/PM composites were used to separate n-hexane/water, silicone oil/water and peanut oil water mixtures via filtration. As a result, they all exhibited efficient separation of oil/water mixture through gravity-driven filtration.

Source profiles and emission factors of VOCs from solvent-based architectural coatings and their contributions to ozone and secondary organic aerosol formation in China

Volatile organic compounds (VOCs) from solvent-based architectural coatings (SBACs) play an important role in photochemical air pollution with increasing consumption of architectural coatings in China. In this study, we collected 148 typical SBACs of 3 types in China. The TVOC emission factors and source profiles were established, the contributions of SBACs to ozone and secondary organic aerosol (SOA) formation were investigated. The VOC emissions and O3 and SOA amounts formed in chemical reactions from SBACs in 2017 were estimated. Key organic groups and VOC species with high reactivity were identified. According to the results, the TVOC emission factors were 507.17 g L−1 for solvent-based anticorrosive coatings, 381.34 g L−1 for solvent-based floor coatings and 459.68 g L−1 for solvent-based fire-retardant coatings. The VOC emissions were 186,902.11 t, 88,225.41 t and 71,352.32 t; the O3 amounts formed were 742,001.39 t, 397,896.60 t and 244,738.46 t; the SOA amounts formed were 3934.29 t, 2488.04 t and 1104.61 t, respectively, from 3 types of SBACs in 2017. The O3 production factors were 1781.82 g O3 (kg paint)−1, 1457.50 g O3 (kg paint)−1 and 1176.63 g O3 (kg paint)−1, the SOA production factors were 9.45 g SOA (kg paint)−1, 9.11 g SOA (kg paint)−1 and 5.31 g SOA (kg paint)−1, for 3 types of SBACs. Priority should be given to organic group of aromatics and top 17 VOC species with high reactivity for O3 and SOA eliminating strategies, especially three xylenes (o-xylene, m-xylene and p-xylene), ethylbenzene, trimethyl benzenes (1,3,5-trimethyl benzene, 1,2,3-Trimethyl benzene) and toluene.