Mechanism of the noncatalytic oxidation of soot using in situ transmission electron microscopy.

Soot generation is a major challenge in industries. The elimination of soot is particularly crucial to reduce pollutant emissions and boost carbon conversion. The mechanisms for soot oxidation are complex, with quantified models obtained under in situ conditions still missing. We prepare soot samples via noncatalytic partial oxidation of methane. Various oxidation models are established based on the results of in situ transmission electron microscopy experiments. A quantified maturity parameter is proposed and used to categorize the soot particles according to the nanostructure at various maturity levels, which in turn lead to different oxidation mechanisms. To tackle the challenges in the kinetic analysis of soot aggregates, a simplification model is proposed and soot oxidation rates are quantified. In addition, a special core-shell separation model is revealed through in situ analysis and kinetic studies. In this study, we obtain important quantified models for soot oxidation under in situ conditions.

Probing the Mechanism of Hepatotoxicity of Hexabromocyclododecanes through Toxicological Network Analysis.

The prediction and mechanism analysis of hepatotoxicity of contaminants, because of their various phenotypes and complex mechanisms, is still a key problem in environmental research. We applied a toxicological network analysis method to predict the hepatotoxicity of three hexabromocyclododecane (HBCD) diastereoisomers (α-HBCD, ß-HBCD, and γ-HBCD) and explore their potential mechanisms. First, we collected the hepatotoxicity related genes and found that those genes were significantly localized in the human interactome. Therefore, these genes form a disease module of hepatotoxicity. We also collected targets of α-, ß-, and γ-HBCD and found that their targets overlap with the hepatotoxicity disease module. Then, we trained a model to predict hepatotoxicity of three HBCD diastereoisomers based on the relationship between the hepatotoxicity disease module and targets of compounds. We found that 593 genes were significantly located in the hepatotoxicity disease module (Z = 11.9, p < 0.001) involved in oxidative stress, cellular immunity, and proliferation, and the accuracy of hepatotoxicity prediction of HBCD was 0.7095 ± 0.0193 and the recall score was 0.8355 ± 0.0352. HBCD mainly affects the core disease module genes to mediate the adenosine monophosphate-activated kinase, p38MAPK, PI3K/Akt, and TNFα pathways to regulate the immune reaction and inflammation. HBCD also induces the secretion of IL6 and STAT3 to lead hepatotoxicity by regulating NR3C1. This approach is transferable to other toxicity research studies of environmental pollutants.

Data on propylene/propane separation by the externally heat-integrated distillation column (EHIDiC) using data-driven analysis.

Nine hundred data were collected from rigorously simulated EHIDiC for propylene/propane separation using the Aspen Plus-Matlab communication platform. Statistical analysis was performed to give a further understanding of EHIDiC, a highly coupled system. The input variables, integrated stages, and the corresponding heat of two couples of external exchangers were generated stochastically in a wide range to cover the completely reasonable operation window. The results of blocks and streams in the flowsheet were calculated as the output data, including the flow rate, the temperature, and the pressure, as well as Total Annualized Cost (TAC). The data can be reused to design and optimize both the steady and dynamic schemes of EHIDiC, especially with machine learning methods. This manuscript gave a full description of collecting and analyzing of the data used in the research article "Data-driven analysis and optimization of externally heat-integrated distillation columns (EHIDiC)" [1].

Nitrogen-doped Carbon Nanospheres-Modified Graphitic Carbon Nitride with Outstanding Photocatalytic Activity.

Metals and metal oxides are widely used as photo/electro-catalysts for environmental remediation. However, there are many issues related to these metal-based catalysts for practical applications, such as high cost and detrimental environmental impact due to metal leaching. Carbon-based catalysts have the potential to overcome these limitations. In this study, monodisperse nitrogen-doped carbon nanospheres (NCs) were synthesized and loaded onto graphitic carbon nitride (g-C3N4, GCN) via a facile hydrothermal method for photocatalytic removal of sulfachloropyridazine (SCP). The prepared metal-free GCN-NC exhibited remarkably enhanced efficiency in SCP degradation. The nitrogen content in NC critically influences the physicochemical properties and performances of the resultant hybrids. The optimum nitrogen doping concentration was identified at 6.0 wt%. The SCP removal rates can be improved by a factor of 4.7 and 3.2, under UV and visible lights, by the GCN-NC composite due to the enhanced charge mobility and visible light harvesting. The mechanism of the improved photocatalytic performance and band structure alternation were further investigated by density functional theory (DFT) calculations. The DFT results confirm the high capability of the GCN-NC hybrids to activate the electron-hole pairs by reducing the band gap energy and efficiently separating electron/hole pairs. Superoxide and hydroxyl radicals are subsequently produced, leading to the efficient SCP removal.

The effect of inorganic salt in wastewater on the viscosity of coal water slurry.

The preparation of coal water slurry (CWS) using wastewater, which contains inorganic and organic components, is one method of wastewater utilization. In this study, the effect of inorganic salts on the viscosity of CWS was examined. The results show that monovalent salts (NaCl, KCl) decreased the viscosity of CWS. The viscosity of CWS was not affected by bivalent salts (CaCl2, MgCl2). However, CWS combined with trivalent salt (AlCl3) sharply increased the viscosity. The zeta potential of CWS with inorganic salts increased which can enhance the electric repulsion and beneficial to reduce the viscosity. The content of free water in CWS with trivalent salt decreased, and the freedom of the free water in CWS with trivalent salt decreased which were all bad to the viscosity and the adsorption of the dispersant on the particles. Compared with the surface polarity of the particles without inorganic salts, the surface polarity of the particles with divalent salts was similar to those without inorganic salts. Under the comprehensive influence, divalent salt has little effect on the viscosity of CWS.

Study on CO2 gasification reactivity and physical characteristics of biomass, petroleum coke and coal chars.

Gasification reactivities of six different carbonaceous material chars with CO2 were determined by a Thermogravimetric Analyzer (TGA). Gasification reactivities of biomass chars are higher than those of coke and coal chars. In addition, physical structures and chemical components of these chars were systematically tested. It is found that the crystalline structure is an important factor to evaluate gasification reactivities of different chars and the crystalline structures of biomass chars are less order than those of coke and coal chars. Moreover, initial gasification rates of these chars were measured at high temperatures and with relatively large particle sizes. The method of calculating the effectiveness factor η was used to quantify the effect of pore diffusion on gasification. The results show that differences in pore diffusion effects among gasification with various chars are prominent and can be attributed to different intrinsic gasification reactivities and physical characteristics of different chars.

Rapid co-pyrolysis of rice straw and a bituminous coal in a high-frequency furnace and gasification of the residual char.

Rapid pyrolysis of rice straw (RS) and Shenfu bituminous coal (SB) separately, and rapid co-pyrolysis of RS/SB blends (mass ratio 1:4, 1:4, and 4:1), were carried out in a high-frequency furnace which can ensure both high heating rate and satisfying contact of fuel particles. Synergies between RS and SB during rapid co-pyrolysis were investigated. Intrinsic and morphological structures of residual char from co-pyrolysis, and their effects on gasification characteristics were also studied. Synergies occurred during rapid co-pyrolysis of RS and SB (RS/SB=1:4) resulting in decreasing char yields and increasing volatile yields. Synergies also happened during gasification of the char derived from co-pyrolysis of RS and SB with mass ratio of 1:4. The increased mass ratio of RS to SB did not only weaken synergies during co-pyrolysis, but significantly reduced the gasification rates of the co-pyrolysis char compared to the calculated values. Results can help to optimize co-conversion process of biomass/coal.

Process simulation of single-step dimethyl ether production via biomass gasification.

In this study, we simulated the single-step process of dimethyl ether (DME) synthesis via biomass gasification using ASPEN Plus. The whole process comprised four parts: gasification, water gas shift reaction, gas purification, and single-step DME synthesis. We analyzed the influence of the oxygen/biomass and steam/biomass ratios on biomass gasification and synthesis performance. The syngas H(2)/CO ratio after water gas shift process was modulated to 1, and the syngas was then purified to remove H(2)S and CO(2), using the Rectisol process. Syngas still contained trace amounts of H(2)S and about 3% CO(2) after purification, which satisfied the synthesis demands. However, the high level of cold energy consumption was a problem during the purification process. The DME yield in this study was 0.37, assuming that the DME selectivity was 0.91 and that CO was totally converted. We performed environmental and economic analyses, and propose the development of a poly-generation process based on economic considerations.

The largest Lyapunov exponent of chaotic dynamical system in scale space and its application.

The largest Lyapunov exponent is an important invariant of detecting and characterizing chaos produced from a dynamical system. We have found analytically that the largest Lyapunov exponent of the small-scale wavelet transform modulus of a dynamical system is the same as the system's largest Lyapunov exponent, both discrete map and continuous chaotic attractor with one or two positive Lyapunov exponents. This property has been used to estimate the largest Lyapunov exponent of chaotic time series with several kinds of strong additive noise.