Distribution Of Functional Groups Research Articles

An updated functional-group-based approach to modeling the vacuum residue oil gasification kinetics

Gasification of heavy petroleum residues can convert low-value feedstock to hydrogen-rich syngas, which can further be used for power generation and/or chemical production. The present work proposed an updated functional-group-based approach (FGMech) to modeling the gasification of a vacuum residue oil (VRO), which is helpful for better understanding the detailed kinetics of the gasification and improving gasifier performance. Elemental, average molecular weight (AMW) and nuclear magnetic resonance (NMR) analyses were conducted experimentally to characterize VRO, including elemental composition, average molecular formula and the functional group distribution, which were further used for model construction. A lumped mechanism for VRO devolatilization was constructed based on the updated FGMech approach: stoichiometric parameters of stable gases, tars and char were obtained from experiments, while those of radicals were based on the multiple linear regression (MLR) correlations; thermodynamic and kinetic parameters were derived from Benson group additivity method and rate rules, respectively. A merged detailed model was adopted for describing the conversion of gases and tars, and a global model was used for char. To test the reliability of the present model approach, Orimulsion gasification experiments from literature were simulated using an integrated perfectly stirred reactor (PSR) and plug flow reactor (PFR) model. It shows that the present model can reasonably predict measured results under various equivalence ratios, and has better performance on the prediction of CH4 compared with most literature models. Based on model analyses, syngas comes from the conversion of C2H4, H2S, CH4 and char in different gasification stages. Benzene, toluene, naphthalene and 1-methylnaphthalene are initial tar species considered in the devolatilization of the VRO. They can undergo hydrogen abstraction acetylene addition (HACA) and C3H3/C5H5 addition reaction pathways to produce large PAHs.

Surface Functionalization of Sugarcane-Bagasse-Derived Cellulose Nanocrystal for Pickering Emulsion Gel: Microstructural Properties and Stability Efficiency.

An environmentally friendly Pickering stabilizer was developed by upcycling sugarcane bagasse (SCB) into a cellulose nanocrystal (CNC), which was subjected to surface modification by using quaternary ammonium compound to enhance its amphiphilic characteristics. The changes in microstructural properties of modified cellulose nanocrystal (m-CNC), such as surface functional group, thermal stability, surface morphology, elemental composition, and particle size distribution were investigated. Results indicated the success of quaternary ammonium compound grafting with the presence of a trimethyl-alkyl chain on the cellulose structure, while the m-CNC preserves the needle-like nanoparticles in length of ~534 nm and width of ~20 nm. The colloidal profile of m-CNC-stabilized oil-water emulsion gels with different concentrations of m-CNC (1-5 wt%), and oil:water (O:W) ratios (3:7, 5:5, 7:3) were examined. The emulsion gel stability study indicated that the optimal concentration of m-CNC (3 wt%) was able to stabilize all the emulsion gels at different O:W ratios with an emulsion index of >80% for 3 months. It is the minimum concentration of m-CNC to form a robust colloidal network around the small oil droplets, leading to the formation of stable emulsion gels. The emulsion gel with O:W ratio (3:7) with 3 wt% of m-CNC rendered the best m-CNC-oil-droplets dispersion. The m-CNC effectively retained the size of oil droplets (<10 μm for 3 months storage) against coalescence and creaming by creating a steric barrier between the two immiscible phases. Furthermore, the emulsion gel exhibited the highest viscosity and storage modulus which was able to prevent creaming or sedimentation of the emulsion gels.

Green degradation of Caragana korshinskii to valuable bio-oils in supercritical CO2-ethanol: Evaluation of CH and O moieties

An eco-friendly supercritical CO2 (scCO2)-ethanolysis system was designed to convert Caragana korshinskii (Ck) into valuable bio-oils. Hydrocarbons and O-containing moieties (CH and O classes) in derived soluble portions (SPs) were evaluated in detail. The results show that scCO2-ethanol has synergistic degradation ability and strong permeability to complex structures. Optimal conditions were determined to be 10 mL g−1 ethanol/Ck ratio, 1 MPa initial CO2 pressure, 300 °C, and 60 min holding time based on the SP yield and the maximum yield is 38.2 wt% with high heating value of 24.06 kJ g−1. The difference of SPs between conventional ethanolysis (SPE) and scCO2-ethanolysis (SPSE) was compared. According to FTIR and GC/MS analyses, the distribution of functional groups and detectable group components is similar, and O-containing species are dominant. Tetrahydrofurans & furans, alkoxy-substituted benzenes & alkoxy-substituted phenols, and ketones & esters are main group components. The characteristic differences of >C-O- and >CO classes are related to the following three aspects: (1) the ring-opening, >C-O- bond cleavage, cyclization, and condensation of cellulose/hemicellulose, (2) the destruction of abundant >Car-O- in lignin, especially guaiacyl and syringyl units, and (3) the formation of ethyl esters promoted by the nucleophilic attack of ethoxy group. Orbitrap MS analysis further confirmed that O-containing species of SPE and SPSE are mainly concentrated in O1-O4 classes, and scCO2-ethanolysis promotes the acquisition of sugars and bioactive fragments from Ck. In addition, the characteristic distribution of On classes in SPSE is related to the release of natural oxygenates, cleavage of weak/intermediate-strength covalent bonds, and dissociation of O-containing macromolecules. This study provides a reference perspective and a potential implementation approach for the clean and efficient utilization of Ck to produce valuable bio-oils.

(Invited) Precise Evaluation of Functional Group Distribution and Reaction Yield for Chemically Treated Carbon Nanohorns by Highly Sensitive SEM-EDS

Single-walled carbon nanohorns (CNHs) have great potential in diverse applications such as catalyst support, energy conversion, and drug carriers. Although chemical functionalization of CNHs is critical for these applications, they inherently form robust spherical “dahlia-like” aggregates, which may inhibit chemical reactivity. Herein, highly sensitive energy-dispersive X-ray spectrometry (EDS) analysis in scanning electron microscopy (SEM) is employed to elucidate the functional group distribution and the reaction yield of CNH dahlia aggregates. First, the technique clearly visualizes the elemental distribution associated with the functional groups on dahlia structures with a sufficient spatial resolution of <10 nm.1 The result exposes that the outer surface of an individual aggregate is functionalized while the inner core remains almost unreacted. Second, the SEM-EDS precisely assesses the reaction yield for functionalized CNHs.2 The sensitive elemental analysis enables the evaluation of functionalization efficiency for sequentially grown polyamidoamine dendrimers on CNH surface, which consistently explains the change of chemical structure according to the reaction process. The details about the functionalization mechanism on CNH surface will be discussed in the conference.[1] H. Nakajima, T. Morimoto, K. Kobashi, M. Zhang, I. K. Sideri, N. Tagmatarchis, and T. Okazaki, Outer-Surface Covalent Functionalization of Carbon Nanohorn Spherical Aggregates Assessed by Highly Spatial-Resolved Energy-Dispersive X-ray Spectrometry in Scanning Electron Microscopy, J. Phys. Chem. C 2020, 124, 25142-25147.[2] H. Nakajima, K. Kobashi, C. Stangel, T. Morimoto, M. Zhang, N. Tagmatarchis, and T. Okazaki, Step-by-step Characterization of a Series of Polyamidoamine Dendrimers on Carbon Nanohorn Surface, submitted.

(Digital Presentation) Polydopamine-Functionalized Bacterial Cellulose As Biopolymer Separator for Lithium-Sulfur Batteries

Li-S chemistry is regarded as promising next-generation battery technology, but the development of Li-S battery technology is severely impeded by the challenges of polysulfide shuttling and lithium dendrite formation. To address these issues, we coated polydopamine on bacterial cellulose (BC) to create a biopolymer separator. BC provides its dense network, while the presence of polydopamine offers dense polar functional groups to curb polysulfide shuttling by confining them in the sulfur cathode side. Such a separator, with the uniform distribution of nanoscale pores and functional chemical groups, also ensures a consistent Li+ flux at the anode surface, thus addressing the problem of lithium dendrite formation. Our results suggest that this polydopamine/BC-based biopolymer separator has superior performance over the commercial polyolefin-based separator. In particular, the Li-S batteries assembled with this biopolymer separator exhibited a specific discharge capacity of 1449 mAh/g at 0.1C and 909 mAh/g at 1C, while showing a small capacity fade of 0.023% per cycle.

Important properties of anion exchange resins for efficient removal of PFOS and PFOA from groundwater

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) present in various water sources have raised a serious concern on their health risk worldwide. Anion exchange is known to be one of the effective treatment methods but the resin properties suitable for theses contaminants have not been fully understood. We examined four commercially available anion exchange resins with different properties (DIAION™ PA312, HPA25M, UBA120, and WA30) and one polymer-based adsorbent (HP20), for their PFOA and PFOS removal in the batch experiment. All or a part of the selected resins were further characterized for their functional group, surface morphology and pore size distribution. The 72 h batch experiment with the 100 mg/L PFOA or PFOS in the laboratory pure water matrix showed a superior capacity of the strong base anion exchange resins, the porous-type HPA25M and PA312, and the gel-type UBA120, for PFOA removal (92.6–97.9%). Among those resins, the high porous HPA25M was suggested most effective due to its remarkably high reaction rate and effectiveness to PFOS (99.9%). In the groundwater matrix, however, the performance of the those anion exchange resins was generally suppressed, causing up to 71% decrease in their removal rates. The least matrix impact was observed for PFOS removal by HPA25M, which indicated the resin's high selectivity to the contaminant. The physiochemical analysis indicated that the presence of relatively large pores (1 nm–10 nm) over HPA25M played an important role in the PFAS removal.

Rational design phosphorylation Mg-Fe layered dioxides nanosheets for efficient capture of uranium from wastewater

As the nuclear industry boomed, lots of uranium has entered the water environment and caused great damage to ecological environment. Designing and preparing efficient uranium adsorption materials is essential to solve the problem. Phosphorylated Mg-Fe layered dioxides (P-MF LDOs) nanosheets with a favorable memory effect were prepared by calcination and in-situ phosphorylation for uranium extraction from wastewater (UEW). The unique phosphating method resulted in a uniform distribution of phosphate functional groups in the surface of LDOs, which gave it great ability for capture of uranium. The adsorption capacity of P-MF LDOs was 2.31 times that of pure MF LDOs. According to the Langmuir model, the theoretical extraction capacity of P-MF LDOs was as high as 909.09 mg g−1, which was significantly higher than that of similar sorbents. Additionally, it exhibited excellent anti-interference ability. The results of the adsorption mechanism study revealed that the binding modes included surface complexation, mineralization reaction, dissolution-precipitation, and memory effect. In conclusion, P-MF LDOs represent a type of highly efficient uranium adsorbent with simple preparation and high adsorption capacity for UEW. This study provides new insights into the development of inorganic clay-based uranium adsorbents.

Tailoring flake size and chemistry to improve impact resistance of graphene oxide thin films

Multilayered graphene oxide (MLGO) possesses high elastic modulus and strength, as well as enhanced resistance to inter-layer sliding from functional groups. This makes it a promising candidate for impact-resistant thin films and nanocomposites. However, the effects functionalization and flake size on the physics of MLGO failure under high-strain rate impact remains to be fully understood. While laser induced projectile impact tests (LIPIT) have enabled microballistic characterization of MLGO, the dynamics of interlayer sliding processes cannot be accurately studied in physical experiments due to resolution challenges of existing techniques. Here we utilize systematically coarse-grained molecular dynamics to simulate MLGO under high-rate microballistic impact, explicitly accounting for functional group distributions while approaching micron-size specimen dimensions. In doing so, we evaluate the effects of oxidation level on the thin films’ ability to dissipate ballistic energy. We additionally explore effects of varying flake size on these systems, improving on studies that only consider infinite flake dimensions. The primary failure mechanism of these thin films (consisting of relatively small flakes) is found to be sliding of the GO flakes as no bonds were broken. We discover that elevated levels of oxidation increase the amount of energy required to penetrate the film, as do larger GO flake sizes as they increase energy dissipation via friction between sliding flakes. These findings illustrate the potential for MLGO films to be tailored for maximum ballistic energy dissipation, providing a starting point to design impact-resistant GO materials for diverse applications.

Comparing physicochemical characteristics and depolymerization behaviors of lignins derived from different pretreatment processes

Lignin valorization is an important part of increasing the economic viability of sustainable biorefineries. Various methods have been proposed for lignin depolymerization. However, the relationship between lignin structure and its depolymerization behavior hasn't been extensively investigated. This research aims to clarify how the structure and composition of lignins derived from different pretreatment processes affect the downstream catalytic conversion. Herein, optimal organosolv lignin yield above 50% in three different solvent systems were obtained. Meanwhile, three types of hydrolyzed lignin were used as reference lignins. Various lignins were comprehensively characterized by elemental analysis, FT-IR, TGA-DSC and Py-GC/MS techniques. Compared with hydrolyzed lignin, organosolv lignin has higher purity, wider functional group distribution, more uniform structure, as well as a lower G/S ratio. Moreover, lignin depolymerization was carried out with a non-noble metal catalyst Ni/Al2O3 and without the addition of H2. The results showed that transetherification and alkylation reaction were enhanced significantly for organosolv lignin. Total depolymerized aromatics yield from organosolv lignin was 4 to 11 times higher than that of hydrolyzed lignin-rich residues. Notably, Methanol-extracted lignin obtained an optimal yield of 29.7 wt% of monomeric aromatics. Methanol can effectively protect benzylic carbocations formed during organosolv pretreatment, thus minimizing the formation of CC bonds.

Advances in Insight of Radial Heterogeneous Microstructure and Its Relevance to Mechanical Properties of Polyacrylonitrile‐Based Carbon Fibers

Polyacrylonitrile‐based carbon fibers (CFs) have demonstrated unparalleled physical and mechanical properties and are considered a promising material for aerospace, transportation, medical devices, and other applications. However, the current understanding of the heterogeneous structure of carbon fiber is still vague, and the relationship between the heterogeneous structure and the mechanical properties of carbon fiber is also unclear. In this review, the literature on the radial heterogeneous structure of CFs is summarized from four points of view: morphological structure, physical properties and chemical structures, mechanical properties, and structural models by combining different characterization tools such as nanoindentation, nanoscale infrared spectroscopy, and synchrotron wide‐angle X‐ray diffraction. First, the size and orientation of graphite microcrystalline, the degree of graphitization, density distribution, modulus distribution, chemical functional group distribution, and other physical and chemical properties of carbon fiber cross‐sectional structures are discussed. Afterward, the relationship between the mechanical properties of carbon fiber and the heterogeneous structure is analyzed. Finally, the currently accepted models of the heterogeneous structure of carbon fibers are summarized and made some suggestions for research on the heterogeneous structure of carbon fibers.

An optimized miniaturized annular rotating flow reactor for controllable continuous preparation of functionalized polysilsesquioxane microspheres

A novel microreaction system based on a miniaturized annular rotating flow reactor (m-ARFR) was developed for the continuous preparation of functionalized polysilsesquioxanes (FPSQs). Compared to conventional batch processes, this new method enables accurate control and flexible adjustment of particle size and morphology of the prepared microspheres. The geometric structure and rotating speed were optimized through CFD simulations and energy analysis. In the optimized m-ARFRs, uniform shear stress and low back-mixing enable the controllable distribution of functional groups and stable slurry flow. By utilizing the flexibility of geometric design, we prepared uniformly functionalized PSQs (FPSQs-NH2) and surface-functionalized PSQs (PAPSQ@PMSQs). During hourly-level operation of m-ARFRs, the yield of microspheres remained at approximately 90% while maintaining a low internal pressure drop of less than 3 kPa, demonstrating the long-term operating stability of the system.

Infrared spectroscopic evaluation for catalytic hydrogenation of biomass and coal using unsupervised and supervised algorithms

Three biomass (rice straw, rice husk and wheat straw) and three coal samples (lignite, subbituminous coal and bituminous coal) were extracted via a thermal dissolution (TD) process, and the TD extracts were treated by catalytic hydrogenation to obtain reaction products. To reveal the similarity in molecular information among the samples and elucidate their chemical reactivity, four machine learning algorithms were applied to analyze the Fourier transform infrared spectra of both TD extracts and catalytic hydrogenation products. Functional groups were used as variables and the difference in peak area can be treated as the basis for sample classification. Aromatic CH, COC, aliphatic CH2 or CH3 and aromatic CO or CC bonds were the main characteristic variables in principal component analysis algorithm to classify biomass- and coal-derivated samples. These samples were also grouped into four clusters by hierarchical clustering analysis algorithm according to the similarity and difference in the distribution of functional groups. For artificial neural network algorithm, aliphatic CH and OH bonds are the most important variables to classify these samples into four groups, and aromatic CH, OH, and COC groups are the main variables contributed to the classification trees in random forest algorithm. Machine learning algorithms will provide methodological guidance for the data mining of the spectra of complex organic systems.

Characterization of Different Metal Oxide Promoted Alumina Catalyst

In this study, different metal oxide alumina promoted catalysts were prepared and characterized. All the catalysts (CaO/Al2O3, CuO/Al2O3, FeO/Al2O3, MnO/Al2O3, NiO/Al2O3 and ZnO/Al2O3) were prepared using the incipient wetness impregnation method followed by drying and calcination. The characterization of all six samples of catalysts was done to determine the surface morphology, porosity, functional group, thermal stability, metal content and particle size distribution. Scanning electron microscope (SEM) analysis of samples showed that there were pores on the surface of the alumina. Mercury intrusion porosimetry (MIP) showed that copper oxide alumina promoted (CuO/Al2O3) had the high porosity which is 36.77 m2/g followed by zinc oxide (ZnO/Al2O3), calcium oxide (CaO/Al2O3) nickel oxide (NiO/Al2O3) manganese oxide (MnO/Al2O3) and ferric oxide alumina promoted (FeO/Al2O3) catalysts. Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of by-product existed in all catalysts. Atomic absorption spectroscopy (AAS) analysis showed the presence of Cu, Fe and Zn in the CuO/Al2O3, FeO/Al2O3 and ZnO/Al2O3, while Ca was absent in CaO/Al2O3. Besides, through thermo-gravimetric analyzer (TGA) and differential thermal analysis (DTA), all the catalysts showed a slight decrease in weight which can be considered as a stable catalyst. The particle size distribution analysis using the Zetasizer showed the particle size mean based on the intensity of CaO/Al2O3, CuO/Al2O3, FeO/Al2O3, MnO/Al2O3, NiO/Al2O3 and ZnO/Al2O3 were 2305 nm, 5560 nm, 5560 nm, 1281 nm, 1281 nm and 3580 nm, respectively.

Composition and morphology of biomass-based soot from updraft gasifier system

Soot is an aerosol formed by incomplete combustion of carbonaceous materials, and its formation in biomass gasification is inevitable. It is crucial to know the properties of the soot produced in the exhaust of gasification reactors in order to appreciate both its advantages and disadvantages. In this study, a variety of analytical techniques were used to examine the content and morphology of biomass soot produced by a top-lit updraft gasifier. The results of the experiment revealed that carbon and oxygen make up the majority of the soot, with minor amounts of other components. Both aromatic and aliphatic groups with significant oxygen concentrations can be seen in the soot based on the distribution of functional groups. The morphology revealed an uneven, stratified, amorphous sample. Meanwhile, the sample had a surface area of 193.8 m2/g and a pore diameter of 2.68 nm. These porous qualities point to a potential use of the soot sample as an adsorbent in water filtration after activation.

Carbon-based solid acids catalyze the synthesis of ethylene glycol monoacetate from ethylene glycol and acetic acid

Activation is essential for improving the structure and surface functional groups of carbon-based solid acids (CSA) during the preparation of carbon materials. This paper compared the catalytic activity of CSA treated non-, KOH-, H3PO4-, and ZnCl2-activation in esterification of ethylene glycol (EG) and acetic acid (HAc) to synthesize ethylene glycol monoacetate (EGMA). The catalysts were characterized using N2 isothermal adsorption–desorption, acid-base titration, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), Raman spectrometer, X-ray photoelectron spectroscopy (XPS), and X-ray diffractometer analysis (XRD). The results showed that activation treatment clearly enhanced the CSA’s specific surface area and significantly influenced the distribution of surface functional groups. Notably, the CSA activated with H3PO4 had a markedly higher density of –SO3H groups than the non- activated, KOH- activated, and ZnCl2-activated CSA. The high density of –SO3H on the catalyst surface is advantageous for the synthesis of EGMA from EG and HAc, making the H3PO4-activated CSA the best performer. The reaction conditions were optimized on H3PO4-activated CSA, resulting in a 74.1% conversion of EG and an 81.8% selectivity of EGMA at 100 °C for 30 min, and the EG/HAc molar ratio of 1:2. H3PO4-activated CSA was not obviously deactivated even after five cycles, and the decrease of its catalytic performance was related to the leaching of –SO3H on the catalyst surface. Overall, these findings suggest that H3PO4-activated CSA offers the benefits of less cost, a simpler preparation method, and greater catalytic activity compared to other catalysts, making it a desirable option for the synthesis of EGMA.

Revealing the Chemical Nature of Functional Groups on Graphene Oxide by Integrating Potentiometric Titration and Ab Initio Calculations.

A new graphene oxide (GO) model with reasonable functional group types and distribution modes was proposed by integrating potentiometric titrations and ab initio calculations. Due to the complex synthesis mechanism, the atomic structure of GO has been controversial for a long time. Here, we use density functional theory calculations to mimic the oxidation process, and a series of GO fragments (GOFs) were deduced. A new pKa calculation method (RCDPKA) developed specifically in this work was further used to predict pKa values of the fragments. Then, we performed potentiometric titrations on four different GO samples to confirm the existence of these GOFs and determine the content of functional groups. Interestingly, different GO samples present the same pKa values in titration, and the results are consistent with the predicted ones. Based on the evidence from titration and calculation, prominent correlations between functional groups could be found. Groups at the edges are mainly double-interactive carboxyls (pKa1 ≈ 3.4, pKa2 ≈ 5.7) and double-adjacent phenolic hydroxyls (pKa1 ≈ 8.8, pKa2 ≈ 12.1), while groups on the plane are mainly collocated epoxies and hydroxyls (pKa1 ≈ 11.1, pKa2 ≈ 13.8) on both sides of the plane with a meta-positional hydrogen bond interaction. These findings were further validated by multiple characterizations and GO modifications. These results not only stimulate a fundamental understanding of the GO structure but also provide a quantitative analysis method for functional groups on GO.

Patterns in soil microbial diversity across Europe

Factors driving microbial community composition and diversity are well established but the relationship with microbial functioning is poorly understood, especially at large scales. We analysed microbial biodiversity metrics and distribution of potential functional groups along a gradient of increasing land-use perturbation, detecting over 79,000 bacterial and 25,000 fungal OTUs in 715 sites across 24 European countries. We found the lowest bacterial and fungal diversity in less-disturbed environments (woodlands) compared to grasslands and highly-disturbed environments (croplands). Highly-disturbed environments contain significantly more bacterial chemoheterotrophs, harbour a higher proportion of fungal plant pathogens and saprotrophs, and have less beneficial fungal plant symbionts compared to woodlands and extensively-managed grasslands. Spatial patterns of microbial communities and predicted functions are best explained when interactions among the major determinants (vegetation cover, climate, soil properties) are considered. We propose guidelines for environmental policy actions and argue that taxonomical and functional diversity should be considered simultaneously for monitoring purposes.

Environmental heterogeneity affecting spatial distribution of phytoplankton community structure and functional groups in a large eutrophic lake, Lake Chaohu, China

The growth and development of phytoplankton are influenced by physico-chemical parameters, which can also affect the spatial distribution of phytoplankton community structure. However, it is unclear whether environmental heterogeneity caused by multiple physico-chemical factors can affect the spatial distribution of phytoplankton and its functional groups. In this study, we investigated the seasonal variation and spatial distribution of phytoplankton community structure and its relationships with environmental factors in Lake Chaohu from August 2020 to July 2021. We recorded a total of 190 species from 8 phyla, which were divided into 30 functional groups, including 13 dominating functional groups. The average annual phytoplankton density and biomass were (5.46 ± 7.17) × 107 cells/L and 4.80 ± 4.61 mg/L, respectively. The density and biomass of phytoplankton were higher in summer ((14.64 ± 20.34) × 107 cells/L, 10.61 ± 13.16 mg/L) and autumn ((6.79 ± 3.97) × 107 cells/L, 5.57 ± 2.40 mg/L), with the M and H2 of dominant functional groups. The dominant functional groups were N, C, D, J, MP, H2, and M in spring, whereas functional groups C, N, T, and Y dominated in winter. The distribution of phytoplankton community structure and dominant functional groups exhibited significant spatial heterogeneity in the lake, which was consistent with the environmental heterogeneity of the lake and could be classified into four locations. Location I had higher phytoplankton density and biomass than the other three locations. Additionally, dominant functional groups M, C, and H2 were present throughout the lake, and all 13 dominant functional groups were observed in Location II. Our findings suggest that environmental heterogeneity is a key factor influencing the spatial distribution of phytoplankton functional groups in Lake Chaohu.

Chain End-Functionalized Dense Polymer Brushes from an Inimer Coating by SI-RAFT.

Polymer brushes with controllable grafting density are grown on an inimer coating bearing Reversible Addition-Fragmentation Chain Transfer polymerization (RAFT) chain transfer agents (CTAs). The inimer coating is cross-linked on the substrate to provide an initiator layer that is stable during exposure to organic solvents at high temperatures. Surface-initiated RAFT is conducted to grow poly(2-vinylpyridine) (P2VP) brushes on the coating at grafting densities approaching the theoretical limits. This methodology allows facile end-group functionalization using an efficient thiol-ene click chemistry. Chain ends were functionalized with low surface energy groups to modulate the location of the untethered chain ends by thermal annealing. At lower grafting densities, the low surface energy groups segregate to the surface upon annealing. This effect is less pronounced at higher grafting densities. Detailed characterization of the brushes at varying grafting densities using X-ray photoelectron spectroscopy (XPS) is presented. In tandem with experiments, Monte Carlo simulations examine the effect of the chain-end group size and selectivity on the conformation of the polymer brush, providing numerical evidence of laterally non-uniform distributions of functional groups at different locations in the brush. Simulations further predict the existence of morphologies with an interlayer formed by spherical micelles rich in functional end groups, demonstrating the possibility of end-group functionalization for synthetic modulation of both brush conformation and chain-end location.

In-situ infrared and kinetic characteristics analysis on pyrolysis of tar-rich coal and macerals

Tar-rich coal is a high-quality coal-based oil and gas resource, pyrolysis of tar-rich coal is crucial to alleviate the world energy crisis and pressure on oil and gas resources. This paper analyzed pyrolysis characteristics of tar-rich coal and macerals and evolution mechanism of main functional groups by thermogravimetric analyzer and Fourier in-situ infrared spectrometer. The thermogravimetry results showed that when the heating rate was 10 ∼ 40 °C·min−1, inertinite's volatile yield was 25.21 %∼27.27 %, significantly lower than that of tar-rich coal and vitrinite, the average activation energy required for tar-rich coal pyrolysis was 185.63 kJ·mol−1, lower than 360.56 kJ·mol−1 of vitrinite, indicating that inertinite had more macromolecular structure and was not easy to be pyrolyzed and volatilized, volatile was more likely to be generated and liberated in tar-rich coal. The results of in-situ infrared analysis showed that coal mainly contained out-of-plane aromatic CH, C-O-C, aliphatic-CH3, –CH2, –CH, C = O, –OH and other major functional group structures. Vitrinite contained more aliphatic-CH2, –CH3, –CH and other aliphatic hydrocarbon structures. Tar-rich coal and vitrinite contained more hydrogen-rich structures such as aliphatic CH and active groups such as free-OH, inertinite contained more ether bonds, C = O and hydrogen bonds, almost no aliphatic hydrocarbons and oxygen-containing active groups, and had stronger structural stability. The results of structural parameter analysis showed that under the same conditions, for vitrinite, the aliphatic chain length and hydrocarbon potential were 1.14 and 2.37, greater than those of tar-rich coal and inertinite. The aromatic degree and aromatic condensation degree were 0.39 and 0.48, lower than those of tar-rich coal and inertinite. The pyrolysis characteristic indexes of tar-rich coal and vitrinite were 90.04 (10-8 %·min−1·°C−3) and 93.64 (10-8%·min−1·°C−3), significantly higher than 30.90 (10-8 %·min−1·°C−3) of inertinite. The above results showed that vitrinite had more aliphatic long chains and alkyl side chain, tar-rich coal and vitrinite had better pyrolysis reaction performance and strong volatilization ability, inertinite had less hydrogen-rich structure, poor pyrolysis reaction performance and stronger stability. Based on the discussion of the relationship between functional groups distribution and reaction performance of tar-rich coal and macerals, variation range of structural parameters with functional groups distribution was obtained.