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The presence of phenol in coal-chemical engineering wastewater is considered a serious environmental issue. The use of enzymes to degrade phenol has received wide attention. G-quadruplex can combine with hemin to form G-quadruplex/hemin, which shows peroxidase-like activity and can be used to degrade phenol. In this work, a novel CNTs-NH2@G-quadruplex/hemin was designed using a single-stranded DNA (ssDNA) that contained G-rich fragments and T-rich fragments. The G-rich fragments assembled with the hemin to form G-quadruplex/hemin; the pyrimidine group of the T-rich fragment could form stable chemical bonds with the amino group, which could be used for immobilization. Characterization analysis of FTIR, XRD and TEM showed that the CNTs-NH2@G-quadruplex/hemin was successfully prepared. Meanwhile, the activity and phenol degradation ability for CNTs-NH2@G-quadruplex/hemin were studied in detail, and the effects of pH, temperature, initial phenol concentration, H2O2 concentration and reusability on the degradation efficiency of phenol were also explored. The results showed that when immobilized, the CNTs-NH2@G-quadruplex/hemin presented good activity, especially under conditions of temperature 30 °C and pH 7.0. Notably, the maximum reaction velocity of CNTs-NH2@G-quadruplex/hemin was increased from 0.016 mM mg−1 min−1 (free enzyme) to 0.056 mM mg−1 min−1. For phenol degradation ability, it was observed that under the conditions of temperature 30 °C, pH 7.0, initial phenol concentration 40 mg L−1, H2O2 concentration 120 mM, enzyme dose 40 mg L−1, more than 90% of phenol could be degraded within 600 min. In addition, the CNTs-NH2@G-quadruplex/hemin still maintained high activity after 10 cycles of phenol removal, demonstrating its appealing potential for practical applications. [ABSTRACT FROM AUTHOR]

To ensure the quality of grain storage, researchers have developed a variety of models for the morphological structure of bulk grain piles. However, traditional characterization methods suffer from issues such as inaccurate models, limited size ranges, and low precision. In this study, x‐ray computed tomography was employed for the first time to capture real three‐dimensional (3D) images, revealing the surface porosity distribution ranging from 30% to 38% along the slice direction and a fractal dimension primarily distributed between 1.45 and 1.47. Moreover, the box counting method was used to determine the representative elementary volume (REV) comprising 600 × 600 × 600 pixels, effectively characterizing pore structure using porosity as an index. Connectivity analysis of the REV was conducted by integrating the refined central axis method and the 3D watershed algorithm. Equivalent diameters of connected pores were mainly distributed between 0.5 and 3.5 mm, with an average pore diameter of 2.22 ± 0.02 mm, an average coordination number of 7.04 ± 0.07, and an average tortuosity of 1.58 ± 0.01. Based on the characteristic parameters of connected pores, an equivalent pore network model (EPNM) was reconstructed for numerical simulation of single‐phase percolation of bulk grain pile. In addition, the constructed experimental platform demonstrates that the constructed EPNM closely corresponds to the real pore structure of the seed body, accurately reflecting pore–throat size, connectivity, and morphological characteristics within the grain pile. Furthermore, this research model can be applied to the study of gas flow, heat transfer, and mass transfer within porous media. [ABSTRACT FROM AUTHOR]

Synergistic fermentation of coal and corn straw is an effective tool to increase biomethane production. However, a large gap exists between the biomethane production conditions of corn straw filling coal mine goafs and laboratory experiments. In order to determine the effect of the field environment on synergistic biomethane production, biomethane production experiments with coal and corn straw were carried out under different conditions to find the key factors restricting the potential of biomethane production. The obtained results showed that various bacterial sources had significant influences on the biomethane production of coal and corn straw, and domesticated bacterial sources provided fermentation systems with more efficient biomethane production capacities than mine water sources. Biomethane production of coal and corn straw was relatively high under mixed conditions, but it was also promoted under unmixed conditions. Different inorganic minerals had different effects on synergistic biomethane production, which varied. For example, calcite, montmorillonite, and kaolin are common minerals in coal‐bearing strata that significantly enhance synergistic biomethane production of coal and corn straw. However, pyrite was found to significantly inhibit the synergistic biomethane production effect of coal and corn straw. Highly metamorphosed anthracite coal also presented biomethane production potential when stimulated by corn straw as a carbon source. The obtained results revealed the influences of different field conditions on the biomethane production of coal and corn straw and provided a reference for the field application of corn straw filling in coal mine goafs. [ABSTRACT FROM AUTHOR]

This study addressed the effect of microbial methane production on the physical properties of a coal reservoir. Two kinds of coal samples before and after anaerobic degradation were tested by a low-temperature liquid nitrogen adsorption test and an isothermal adsorption and diffusion coefficient test. The influence of the characteristics of microbial gas production on the coal physical properties was analyzed. Due to the differences in the physical properties of the coal samples, the effect of microbial production is different. Coal is a macromolecular organic compound, mainly aromatic and lignin derivatives, containing carbon and nitrogen sources that can be used by microorganisms. Microorganisms secrete extracellular enzymes to decompose covalent bonds and functional groups of macromolecules in coal and eventually produce methane, which will change the physical properties of coal. It was found that microbial anaerobic degradation could increase the content of coalbed methane, change the pore structure of coal, reduce the fractal dimension of the coal surface and smooth the coal surface. At the same time, microbial degradation has changed the physical properties of coal reservoirs to some extent, increased the diffusion of coal reservoirs and improved the pore connectivity of coal reservoirs, which provides more of a scientific basis for the development of coalbed methane. [ABSTRACT FROM AUTHOR]