Distribution Of Functional Groups Research Articles

New insight into the mechanism of isomerization of C5–C7 alkanes over MoO3/FST

Molybdenum trioxide doped on fibrous silica-titania (MoO3/FST) has been synthesized and evaluated in the catalytic isomerization of C5–C7 for the first time. The structure characterization, functional group, and acid distribution of MoO3/FST were assessed via XRD, N2-physisorption, FTIR, and Py-IR analysis. The IR spectra revealed that MoO3/FST was occupied by a moderate-to-strong Brønsted and Lewis acid sites distribution. By adding MoO3, intense metal-support interactions were formed, lessening Brønsted acid sites' intensity in contrast to the increasing Lewis acid sites' intensity. The isomerization test demonstrated that maximum conversions of 50.0, 80.0, and 84.0% were acquired at 300 °C corresponding to n-C5, n-C6, and n-C7, respectively. As the isomerization temperature rose from 150 to 350 °C, the yield of n-C5 to n-C7 isomers increased to ∼70.0%. The high activity of MoO3/FST was ascribed to the effective interaction between MoO3 with perturbed silanol groups, which led to enrichment in protonic acid site formation via H2 spillover. This finding proves that the isomerization catalysts should possess great Lewis acid and Bronsted acid sites to enrich the protonic acid side, resulting in high performance in isomerization.

Application of dual-solvent extraction for separating a low-temperature coal tar: A detailed experimental and quantum chemical study

A low-temperature coal tar (LTCT) was separated by dual-solvent systems to realize its value-added utilization. Cumulative extract yield (CEY) versus time, extraction kinetics at different stages, extracted composition, and functional group distribution were intensively studied using nonlinear fitting, linear fitting, gas chromatograph/mass spectrometer (GC/MS), and Fourier transform infrared (FTIR) spectrometer, respectively. The relationship between CEY and time conformed to logistic model, and the determination coefficient is 0.97. Among the 3 extraction stages, the slope of the kinetic fitting curves in their extraction stage using petroleum ether (the first 3 runs) in the highest extract yield is 7.5 and 5 times that using methanol and carbon disulfide extraction stage, respectively. Alkanes, arenols, and arenes can be enriched into petroleum ether, methanol, and carbon disulfide, respectively. A total of 314 compounds detected in the LTCT and extracts with GC/MS were subdivided into 85 group components. The result of FTIR analysis is consistent with that of GC/MS. Separation mechanism was expounded by theory analysis and quantum chemistry from hydrogen bonds (O-H···O) and van der Waals force. Quantum chemical calculations show that the attraction of alkane, alkene, anthracene, and naphthalene with n-hexane or carbon disulfide is mainly dispersive interaction, while the attraction of methanol with phenols is mainly electrostatic interaction. Although the bond length of O-H···O formed between methanol and phenols is 2/3 of that of C-H···O, and the bond angle is ca. 45° larger, the binding energy is 9 times that of the latter, indicating that the main hydrogen bonds are O-H···O. In summary, dual-solvent extraction has considerable potential to separate alkanes, arenols, and arenes from the LTCT.

Temporal-spatial distribution and ecological evaluation of macroinvertebrate functional feeding groups in Yongding River Basin

We investigated community structure of macroinvertebrate, water environment factors, hydrological factors at 23 sampling sites of the Yongding River basin from spring 2017 (April) to autumn 2017 (November). We analyzed the composition, spatial and temporal distribution of the macroinvertebrate functional feeding groups, as well as their responses to changes in riverine habitat. A total of 78 macroinvertebrate species were identified, with 52, 50 and 53 macroinvertebrate species in spring, summer and autumn respectively. The dominant functional feeding groups were gather-collectors, followed by predators, while the proportion of scrapers, filter-collectors and shredders were extremely low. Dominant species in the three seasons were all gather-collectors, including Orthocladius, Rheotanytarsus, Cricotopus in spring, Glyptotendipes in summer, and Polypedilum, Chironomus, Orthocladius in autumn. Results of redundancy analysis showed that the functional feeding groups of macroinvertebrate community structure were mainly influenced by water temperature, flow velocity, salinity, and total phosphorus in spring, by total phosphorus, dissolved oxygen, conductivity and flow capacity in summer, and by total phosphorus and dissolved oxygen in autumn. Total phosphorus had positive correlation with gather-collectors in all three seasons, indicating that the functional feeding groups of macroinvertebrates were affected by water pollution. The evaluation based on the metrics of functional feeding groups showed that: 1) in terms of material cycle, primary productivity of Guishui River were significantly higher than other regions, and that in autumn were significantly higher than other seasons. The secondary productivity and decomposition capacity of Yanghe River were significantly higher than other regions, and those in spring were significantly higher than other seasons. The autotrophy/heterotrophy of Yanghe River was significantly lower than other regions, and that in spring were significantly higher than other seasons. 2) The longitudinal transport capacity of Sanggan River was significantly higher than other regions, and that in autumn was significantly higher than other seasons. 3) The lateral input capacity of Guishui River was significantly higher than other regions, and that in summer was significantly higher than other seasons.

Macroinvertebrate Community Composition in Wetlands of the Desert Southwest is Driven by wastewater-associated Nutrient Loading Despite Differences in Salinity.

The online version contains supplementary material available at 10.1007/s13157-022-01647-2.

Karst Dolines Support Highly Diversified Soil Collembola Communities—Possible Refugia in a Warming Climate?

Karst dolines, as geomorphologically diverse natural landforms, usually exhibit more or less steep microclimatic gradients that provide a mosaic of diverse microhabitat conditions, resulting in a high diversity of soil biota with numerous rare endemic and/or relict species occupying these habitats. In this study, we investigated the spatial patterns of Collembola abundance, species richness, community structure and distribution of functional groups at topographically and microclimatically different sites across three open (unforested) karst dolines in a north-south direction in the Slovak Karst, Slovakia. We also assessed the refugial capacity of dolines for collembolan communities. The Friedman ANOVA test confirmed the significant differences in soil mean temperatures between the sites of all the dolines selected. The diverse soil microclimatic conditions within the dolines supported higher Collembola diversity (species numbers, diversity indices) compared with sites on the karst plateau and showed a potential to facilitate the persistence of some species that are absent or very rare in the surrounding landscape. In dolines with circular morphology and comparable size, the topography and soil microclimate had a stronger effect on community composition and structure than soil organic carbon. Shallow solution dolines provided microhabitats for various functional groups of soil Collembola in relation to the microclimatic character of the individual sites. It was observed that such landforms can also function as microclimatic refugia for cold-adapted species through the accumulation of colder air and the buffering of the local microclimate against the ambient mesoclimate, thus underlying the necessity of adequate attention in terms of the conservation of the karst natural phenomena.

Probing the electronic properties of chemically synthesised doped and undoped graphene derivative

Controlled oxidation and reduction are both responsible in determining the distribution of functional groups in graphene derivatives. These functional groups are accountable for showing different types of electrical conductivity in reduced graphene oxide (rGO) and nitrogen-doped rGO (N-rGO). The study reports a new approach to obtain different electronic grades of N-rGO by simply treating rGO with ammonia solution at different temperatures. Using Hall measurements, the electrical properties of rGO and N-rGO are examined, and their conductivity type, sheet carrier density, and resistivity are calculated. The presence of oxygen-containing functional groups causes p-type conductivity in rGO but N-rGO possesses a completely different set of electronic properties due to differently aligned nitrogen-atoms in the exfoliated layers. The amount of ammonia used and the temperature at which it is synthesised are both important in the synthesis of N-rGO. Complete n-type conductivity or compensated n-type conductivity is observed in different types of N-rGOs.

Elucidating NO coupling effects on ignition of toluene reference fuels by chemical functional group analysis

Derived cetane number (DCN), Research and Motor Octane Numbers (RON and MON) have been fundamentally analyzed using Quantitative Structure-Property Relationship (QSPR) regression models with key chemical functional groups. Both RON and MON exhibit strong sensitivities to the abundances of (CH2)n and benzyl-type groups but lack sensitivity to the CH3 group, most dominant in real gasolines. Residual and EGR gases contain NOx known to synergize with fuel autoignition chemistry. Two TRF mixtures having high and low aromatic content but sharing the same RON and MON values were used to evaluate NOx coupling effects. DCN measurements with NO addition were found to be strongly correlated with the abundance of the (CH2)n group. Similar experiments of 200 ppm NO in a Rapid Compression Machine show promotion (inhibition) of ignition for the high (low) aromatic TRF fuel. Kinetic modeling attributes the promotion to the NONO2 interconversion reactions, NO + HO2 = NO2 + OH, CH3 + NO2 = CH3O + NO and NO2 + H = NO + OH. The inhibitive effect relates specifically to low temperature kinetics and high NO loading conditions, leading to the formation of meta-stable species (e.g. CH3 + NO2 (+M) = CH3NO2 (+M)) that decelerate the rate of conversion of HO2 to more reactive OH radicals. The coupling of NO with real gasolines depends on chemical composition and temperature conditions not only encompassed by RON and MON criteria, but by the chemical functional group characteristics. The relevance of this finding to the significance of preferential vaporization of multi-component gasolines on low-speed pre-ignition (LSPI) is discussed. Within the context of chemical functional group distributions of five distillation cuts of a marketed ethanol-free gasoline determined by NMR spectroscopy, the analyses identify considerable variations of key functionalities with fuel distillation properties, indicating chemical kinetic autoignition behaviors that are dependent on preferential vaporization.

Designing mechanically tough graphene oxide materials using deep reinforcement learning

Graphene oxide (GO) is playing an increasing role in many technologies. However, it remains unanswered how to strategically distribute the functional groups to further enhance performance. We utilize deep reinforcement learning (RL) to design mechanically tough GOs. The design task is formulated as a sequential decision process, and policy-gradient RL models are employed to maximize the toughness of GO. Results show that our approach can stably generate functional group distributions with a toughness value over two standard deviations above the mean of random GOs. In addition, our RL approach reaches optimized functional group distributions within only 5000 rollouts, while the simplest design task has 2 × 1011 possibilities. Finally, we show that our approach is scalable in terms of the functional group density and the GO size. The present research showcases the impact of functional group distribution on GO properties, and illustrates the effectiveness and data efficiency of the deep RL approach.

Methanogen Levels Are Significantly Associated with Fecal Microbiota Composition and Alpha Diversity in Healthy Adults and Irritable Bowel Syndrome Patients.

Hydrogenotrophic microbes, primarily including the three functional groups methanogens, sulfate-reducing bacteria, and reductive acetogens, use hydrogen as an energy source and play an important role in maintaining the hydrogen balance in gut ecosystems. A distorted hydrogen balance has been associated with irritable bowel syndrome (IBS). However, the role of hydrogenotrophic microbes in overall microbiota composition and function remains largely unknown. This study aims to assess the distribution and stability of hydrogenotrophic functional groups in healthy adults (HAs) and IBS patients and their association with overall microbiota composition and IBS symptoms. A two-time-point study with 4 weeks in between was performed with 27 HAs and 55 IBS patients included. Our observations revealed that methanogens showed a bimodal distribution across samples. A high-level methanogen microbiota was consistently associated with higher alpha diversity, and its composition was significantly different from that of individuals with a low-level methanogen microbiota. In general, these associations were more pronounced in IBS patients than in HAs. The differences in the copy numbers of genes indicative of total bacteria and acetogens between HAs and IBS patients and their correlations with IBS symptom severity, anxiety, depression, and quality of life (QoL) were sampling time dependent. Hydrogenotrophic functional groups did not show negative abundance correlations with each other in HAs and IBS patients. These findings suggest that methanogen levels in the gut have a pronounced association with microbiota alpha diversity and composition, and the interactions between hydrogenotrophic functional groups are complex in gut ecosystems. IMPORTANCE Hydrogenotrophic microbes play an essential role in the disposal of hydrogen and the maintenance of the hydrogen balance in gut ecosystems. Their abundances vary between individuals and have been reported to be associated with human gut disorders such as irritable bowel disease. This study confirms that methanogen levels show a bimodal distribution. Moreover, a high-level methanogen microbiota was associated with higher alpha diversity, and its composition was different from that of individuals with a low-level methanogen microbiota. These associations are more pronounced in IBS patients than in healthy subjects. In addition, associations between hydrogenotrophic microbes and IBS symptom scores vary over time, which argues for the use of longitudinal study designs. Last but not least, this study suggests that the different hydrogenotrophic microbes coexist with each other and do not necessarily compete for hydrogen in the gut. The findings in this study highlight the impact of methanogens on overall microbiota composition and function.

High-velocity transverse impact of monolayer graphene oxide by a molecular dynamics study

2D materials have attracted tremendous attention recently due to their unique characteristic under extreme loading conditions such as impact. Owing to its exceptional mechanical properties and low cost of processing, graphene oxide (GO), which is a 2D amorphous material, has been widely utilized as a nanocomposite building block under such loading conditions. To date, extensive researches have been conducted to unravel the chemistry-dependent mechanical properties of GO. Nonetheless, high-velocity impact characterization of single-layer GO received less attention. Therefore, the aforementioned problem is investigated using ReaxFF molecular dynamics simulations in this work. Accordingly, the penetration-resistance of single-layer GO with different oxidation levels under nano-projectile impact is assessed. It is found that (a) as oxidation level increases the onset of complete perforation velocity decreases, (b) penetration-resistance is influenced by hydroxyl-to-epoxide ratio for a fixed oxidation level, and (c) spatial distribution of oxygen functional groups alters the perforation-resistance of a monolayer for the same oxidation level. The findings of this study may provide some insights into the design of surface coatings and novel protective barriers in which GO is used as reinforcement nanofillers.

Global distribution of soil fauna functional groups and their estimated litter consumption across biomes

Soil invertebrates (i.e., soil fauna) are important drivers of many key processes in soils including soil aggregate formation, water retention, and soil organic matter transformation. Many soil fauna groups directly or indirectly participate in litter consumption. However, the quantity of litter consumed by major faunal groups across biomes remains unknown. To estimate this quantity, we reviewed > 1000 observations from 70 studies that determined the biomass of soil fauna across various biomes and 200 observations from 44 studies on litter consumption by soil fauna. To compare litter consumption with annual litterfall, we analyzed 692 observations from 24 litterfall studies and 183 observations from 28 litter stock studies. The biomass of faunal groups was highest in temperate grasslands and then decreased in the following order: boreal forest > temperate forest > tropical grassland > tundra > tropical forest > Mediterranean ecosystems > desert and semidesert. Tropical grasslands, desert biomes, and Mediterranean ecosystems were dominated by termites. Temperate grasslands were dominated by omnivores, while temperate forests were dominated by earthworms. On average, estimated litter consumption (relative to total litter input) ranged from a low of 14.9% in deserts to a high of 100.4% in temperate grassland. Litter consumption by soil fauna was greater in grasslands than in forests. This is the first study to estimate the effect of different soil fauna groups on litter consumption and related processes at global scale.

Source apportionment and evolution of N-containing aerosols at a rural cloud forest in Taiwan by isotope analysis

Abstract. Ammonium and nitrate are major N-containing aerosol components. The deposition of N-containing aerosols has impacts on regional ecology and the biogeochemical cycle. In this study, aerosols in a rural cloud forest (Xitou in Taiwan) were studied using 15N and 18O isotope analysis to assess the sources and formation pathways of the local N-containing aerosols linking to a metropolitan. Aerosol samples of different size ranges were collected using a micro-orifice uniform deposit impactor (MOUDI) on a half-day basis in December 2018. The chemical functional groups were analyzed using a Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) technique, while the isotope analysis was performed using a gas chromatography–isotope ratio mass spectrometer (GC–IRMS). The average measured aerosol concentration (PM10) was 0.98 (ranging from 0.15 to 3.31) and 0.25 (ranging from 0.00 to 1.51) µg m−3 for NH4+ and NO3-, respectively. In general, a higher concentration than nighttime was observed during the daytime by a factor of 1.5–6, likely due to the transportation of pollutants from upper-stream urban and industrial regions through the local sea breeze combined with valley wind. The presence of fog can further elevate the concentration by a factor of 2–3, resulting from the stronger inversion and lower boundary layer height. The higher NH4+ concentration in fine particles under foggy conditions corresponds to submicron-sized NO3- formation via aqueous-phase dissolution with NH4+ neutralization. Furthermore, the higher RH during fog events shifted the mass distribution of aerosol functional groups to a larger mode size. By comparing the δ15N value directly or through the analysis using a statistical isotope mixing model, MixSIAR, NH4+ probably originated from the industries, coal-fired power plants (CFPPs), or fertilizer plants, while NO3- might be contributed from the CFPP, industrial or urban sources. The overall δ18O of NO3- is +72.66 ‰ ± 3.42 ‰, similar to that in other winter Asian studies, suggesting the major formation pathway via O3 oxidation (δ18O=+72.5 ‰ to 101.67 ‰). However, a lower δ18O (<+67 ‰) for particles less than 0.56 µm during foggy daytime suggests the local contribution via the peroxyl radical oxidation before partitioning into aerosol phase under foggy conditions. Overall, the δ15N and δ18O distribution profiles as a function of particle size in the studied rural forest site reveal the evolution of aerosol composition from remote coastal regions with chemical processes along the transport process, which can be further affected by weather conditions such as fog events.

Moist-electric films based on asymmetric distribution of sodium alginate oxygen-containing functional groups

Moist-electric generation as a green process of power generation can effectively solve energy and environmental problems. In order to improve the moist-electric properties of moist-electric generator (MEG), this study designed and prepared a sodium alginate (SA)/multi-walled carbon nanotube (MWCNT) bilayer film hygroscopic generator with an asymmetric distribution of oxygen-containing functional groups (asym-SCM) by simple freeze-drying and pressing. The relative ratios of carbon and oxygen in the system were adjusted by changing the ratios of SA/MWCNT, and the advantages of constructing an asymmetric distribution of oxygen-containing functional groups on the moist-electrical properties of the material were verified. The asym-SCM MEG is able to draw moisture from the environment, generating an open circuit voltage up to ca. 0.65 V at low humidity (ca. 40%) and generating power continuously for up to 650 min. At 90% humidity, the asym-SCM MEG can achieve an output voltage of ca. 0.78 V, well above the power generation performance of most biomass materials moist-electric studies in the current phase. This MEG is green, biocompatible, biodegradable, promising to be used as a self-powered device for flexible wearable, biomedical and other applications.

The Spontaneous Combustion Potency of Lignite Coal Based on FTIR

To understand the role of functional groups in the spontaneous combustion of lignite coal, the distribution of functional groups in the lignite coal of the Sajau Formation in the Berau Basin, Indonesia, was studied. The functional group characterization was carried out using the Fourier Transform Infra Red (FTIR) method. The results revealed the presence of four functional groups, namely hydroxyl structures, aliphatic structures, oxygen-containing structures, and aromatic structures. The lignite contained more hydroxyl and oxygen-bearing functional groups, from which aliphatic and aromatic; therefore, spontaneous combustion becomes easy in lignite coal.

Functional traits above and below ground allow species with distinct ecological strategies to coexist in the largest seasonally dry tropical forest in the Americas

Plant functional strategies are well-established for low- and high-stress environments, such as rainforests and deserts. However, in environments with low- and high-stress level fluctuation within years, the relationship between plant functional strategies and their spatial distribution is still poorly understood. We aimed to answer: what are the relationships between above- and below-ground traits in the largest seasonally dry tropical forest in the Americas? Do the studied species form detectable groups from the functional perspective? If detectable, do functional groups present distinct spatial distributions across the domain, mediated by spatial heterogeneity of aridity? We sampled a range of 16 above- and below-ground traits from the 20 most common native tree species. We performed a PCA to understand the species' main coordinated trade-offs, a k-mean analysis to test for functional groups, and a Ripley's-K analysis followed by a GLS model to test spatial functional groups distribution through the aridity gradient. We found five coordinated trade-offs representing different aspects of the conservative-acquisitive strategy continuum. Drought-tolerance and avoidance mechanisms seem linked to the conservative-acquisitive gradient, where water storage is positively correlated with acquisitive strategies. Different from other seasonally dry regions, acquisitive strategies are not limited by aridity. The presence of short-term water storage traits might buffer rainfall fluctuations, allowing acquisitive species to occupy more arid regions. This study sheds new light on the functional complexity of species from Americas seasonally dry tropical forests, for the first time including the relationship of its below- and above-ground traits.

Renewable nitrogen-containing products by Maillard reaction of sewage sludge and glucose. Part I. Analysis of nitrogen composition and protein model based on AlphaFold2

• Composition, content, and structure of protein-N in sludge were investigated. • Distribution and relative content of Maillard reaction-related functional groups. • Trace the origin of protein by microbial community and protein function analysis. • Sludge protein model is predicted by Alphafold2. • Crucial factors of sludge protein model for Maillard reaction are proposed. In order to better understand the nitrogen transformation in Maillard reaction during the co-pyrolysis of sewage sludge (SS) and glucose, analysis of Maillard reaction-related nitrogen-containing compounds (NCCs) and the protein model of SS is proposed. The composition, content, and structure of NCCs, especially protein in SS, are critical for the investigation of nitrogen transformation in Maillard reaction. The distribution and relative content of Maillard reaction-related functional groups, NCCs, and amino acids in SS were studied. Genomes by DNA sequencing are further applied in building a database search for metaproteomic studies, which provide valuable information and insight into the origin of SS protein, such as the taxonomic composition of the underlying microbial community, inferred protein functions, and their relationship with the transformation of NCCs. SS protein model was constructed by Alphafold2, and key factors determining the selection of SS protein model were revealed.

Insight into the separation mechanism of coal macerals by micro characterization and density functional theory calculation

It is of great significance to reveal the specific separation behavior of macerals for realizing the classification and utilization of coal resources. In this article, the separation mechanism of macerals during coal upgrading was investigated experimentally and computationally based on an improved hydrothermal float-sink method combined with various characterization approaches. The apparent morphology, endogenous mineral and aromatic structural differences of macerals were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM). Materials Studio was applied to calculate the adsorption conformation, energy, charge density difference and bonding tendency of heavy media with functional groups in coal to elucidate the interaction between macerals and heavy liquids. The results show that the float-sink procedure with water bath heating instead of the previous strong acid inhibitor can achieve a purity of more than 75% and 60% for vitrinite and inertinite, respectively. Further refinement of coal particle size can enhance the yield of vitrinite with lightweight, which is less dense due to its lower aromatization than inertinite. In addition, the partial distribution of characteristic functional groups in coal on the surface of inertinite enhances the adsorption between it and heavy liquid, thereby affecting the separation behavior. Therefore, the mechanism of separation and enrichment of macerals by the float-sink method lies in the density difference of individual components and the interaction between the functional groups of each maceral and ZnCl2 solution.

Meta‐ecosystem dynamics drive the spatial distribution of functional groups in river networks

The meta‐ecosystem concept provides a theoretical framework to study the effect of local and regional flows of resources on ecosystem dynamics. Meta‐ecosystem theory has hitherto been applied to highly abstract landscapes, and meta‐ecosystem dynamics in real‐world landscapes remain largely unexplored. River networks constitute a prime example of meta‐ecosystems, being characterized by directional resource flows from upstream to downstream communities and between the terrestrial and the aquatic realm. These flows have been thoroughly described by the River continuum concept (RCC), a seminal concept in freshwater ecology, stating that observed spatial variations in the relative abundances of invertebrate functional groups reflect systematic shifts in types and locations of food resources, which are in turn determined by the physical attributes of river reaches. Hence, the RCC represents a solid conceptual basis for determining how changes in landscape structure and resource flows will translate into local and regional changes in community composition. Here, we develop and analyse a riverine meta‐ecosystem model inspired by the RCC, which builds upon a physically‐based landscape model of dendritic river networks. We show that the spatial distributions and regional biomass of invertebrate functional groups observed in stream communities are determined by the spatial structure and scaling attributes of dendritic river networks, as well as by specific rates of resource flows. Neglecting any of these aspects in modelling river meta‐ecosystems would result in different community patterns. Moreover, we observed that high rates of resource flow, for example due to river anthropization, have a negative effect on the regional biomass of all functional groups studied, and can lead to cascading extinctions at the meta‐ecosystem scale. Our work paves the way for the development of physically‐based meta‐ecosystem models to understand the structure and functioning of real‐world ecosystems.

Mechanical behavior and failure mechanism of multilayer graphene oxides with various oxygen contents and functional types: A ReaxFF molecular dynamics simulation

An in-depth understanding about the failure mechanism of graphene oxide and its relationship with structure and temperature is essentially important to improve the mechanical properties of graphene oxides. In this work, a series of comparison groups have been established to investigate the effects of oxygen-containing functional group density, the number of layers, temperature, and hydroxyl to epoxy group ratio on the mechanical properties of monolayer and multilayer graphene oxides through ReaxFF molecular dynamics simulations. It is demonstrated that the position of functional group distribution plays a decisive role in the mechanical properties of graphene oxide. Meanwhile, the active thermal motion of atoms at high temperatures leads to a more fracture-prone structure, but the multilayer graphene oxide is less sensitive to temperature compared to monolayer graphene oxide. In addition, the structure with more hydroxyl groups has better mechanical properties because the distortion energy of the carbon skeleton caused by hydrogen groups is much smaller than that of epoxy groups. This study provides directions and possibilities for the optimization of the mechanical properties of graphene oxide.

Insights into olation reaction-driven coagulation and adsorption: A pathway for exploiting the surface properties of biochar

In this study, characterization of biochar for the efficient removal of cadmium was investigated. Biochar has a specific distribution of functional groups on its surface and has a natural electronegativity. Using carbonate as an olation reagent, the biochar coagulates with the olation reaction products. The maximum removal capacity reached 430.4 mg/g at pH = 4 (Langmuir Fit). Carbonate hydrolyzed on the surface of biochar, Cd2+ in solution undergoes olation with OH− and forms specially structured nanochains that are positively charged on the surface. The biochar with electronegativity on the surface coagulates with the cadmium hydroxide nanochains, and the cadmium-containing colloid formed by electrostatic attraction settles rapidly and removed. The biochar's re-flocculation performance was consistent, and the loadings could be changed to effectively remove cadmium while keeping the pH neutral at equilibrium.