Nitrogen Adsorption Experiments Research Articles

Using Fractal Theory to Study the Influence of Movable Oil on the Pore Structure of Different Types of Shale: A Case Study of the Fengcheng Formation Shale in Well X of Mahu Sag, Junggar Basin, China

This study investigated the influence of movable oil on the pore structure of various shale types, analyzing 19 shale samples from Well X in the Mahu Sag of the Junggar Basin. Initially, X-ray diffraction (XRD) analysis classified the shale samples. Subsequently, the geochemical properties and pore structures of the samples, both pre and post oil Soxhlet extraction, were comparatively analyzed through Total Organic Carbon (TOC) content measurement, Rock-Eval pyrolysis, and nitrogen adsorption experiments. Additionally, fractal theory quantitatively described the impact of movable oil on the pore structure of different shale types. Results indicated higher movable oil content in siliceous shale compared to calcareous shale. Oil extraction led to a significant increase in specific surface area and pore volume in all samples, particularly in siliceous shale. Calcareous shale predominantly displays H2–H3 type hysteresis loops, indicating a uniform pore structure with ink-bottle-shaped pores. Conversely, siliceous shale exhibited diverse hysteresis loops, reflecting its complex pore structure. The fractal dimension in calcareous shale correlated primarily with pore structure, exhibiting no significant correlation with TOC content before or after oil extraction. Conversely, the fractal dimension changes in siliceous shale samples do not have a clear correlation with either TOC content or pore structure, suggesting variations may result from both TOC and pore structure.

Promising CO2 Capture and Effective Iodine Adsorption of Hyper-Cross-Linked Conjugated Porous Organic Polymers Prepared from a Cyclopentannulation Reaction.

Three novel conjugated porous organic polymers, denoted as C-POP1-3 and which consist of alternating pyrene cores with various contorted fluorene surrogates, were successfully synthesized from a versatile one-pot palladium-catalyzed [3+2] cyclocondensation reaction. The resulting polymers were obtained in excellent yields and displayed weight-average molecular weights (Mw) ranging from 12.2 to 20.2 kg/mol with polydispersity indices (Mw/Mn) ranging between 1.8 and 2.4, suggesting that the molecular masses are narrowly distributed and thus implying homogeneous polymer chains. Thermal stability exploration of C-POP1-3 by thermogravimetric analysis (TGA) revealed an impressive robustness with a 10% weight reduction temperature attaining 485 °C. Investigation of the inherent microporosity properties of C-POP1-3 via nitrogen adsorption experiments using Brunauer-Emmett-Teller (BET) theory discloses their surface areas which reach up to 560 m2 g-1 and pore volumes averaging 0.47 cm3 g-1. The target conjugated polymers were explored as adsorbents disclosing a maximum carbon dioxide adsorption of 83.0 mg g-1 at 273 K and low pressure for C-POP1, whereas iodine sorption tests portrayed prominent outcomes, notably for C-POP3 which proved to owe a strong affinity toward the hitherto mentioned halogen by achieving a maximum adsorption of 2220 mg g-1. Additionally, recyclability experiments confirmed the possibility to regenerate the polymers' adsorption capabilities even after seven consecutive cycles of adsorption-desorption cycles, which qualify them as auspicious iodine adsorbents.

Reservoir Characteristics of the Main Coal Seams in the Longtan Formation, Guxu Coal Mining Area, Sichuan

To facilitate the efficient exploration and development of coalbed methane of the Longtan Formation in the Guxu coal mining area, Sichuan, it is essential to evaluate the reservoir characteristics of the main production layers. In this study, scanning electron microscopy, low-temperature liquid nitrogen adsorption experiments, high-pressure mercury pressure experiments, and isothermal adsorption experiments were conducted to investigate the reservoir characteristics of favorable coalbed methane reservoirs. The results indicate that the main coal seams in the Longtan Formation are medium-to-high ash content anthracite with a well-developed pore–fracture system. The pore size distribution exhibits both unimodal and bimodal types, while the pore morphology includes impermeable pores closed at one end, open permeable pores, and ink bottle-shaped pores. It shows that the middle part of Longtan Formation acts as an enrichment zone for coalbed methane, which is characterized by a stronger adsorption capacity, high Langmuir volume, high gas content, and high gas saturation distribution. The pH value, mineralization degree, and hydrogen–oxygen isotope of the produced water in the main coal seams indicate that the enrichment zone is typically located in a stagnant flow zone with a reducing environment and favorable storage conditions.

Reservoir characteristics and formation model of Upper Carboniferous bauxite series in eastern Ordos Basin, NW China

Through core observation, thin section identification, X-ray diffraction analysis, scanning electron microscopy, and low-temperature nitrogen adsorption and isothermal adsorption experiments, the lithology and pore characteristics of the Upper Carboniferous bauxite series in eastern Ordos Basin were analyzed to reveal the formation and evolution process of the bauxite reservoirs. A petrological nomenclature and classification scheme for bauxitic rocks based on three units (aluminum hydroxides, iron minerals and clay minerals) is proposed. It is found that bauxitic mudstone is in the form of dense massive and clastic structures, while the (clayey) bauxite is of dense massive, pisolite, oolite, porous soil and clastic structures. Both bauxitic mudstone and bauxite reservoirs develop dissolution pores, intercrystalline pores, and microfractures as the dominant gas storage space, with the porosity less than 10% and mesopores in dominance. The bauxite series in the North China Craton can be divided into five sections, i.e., ferrilite (Shanxi-style iron ore, section A), bauxitic mudstone (section B), bauxite (section C), bauxite mudstone (debris-containing, section D) and dark mudstone-coal section (section E). The burrow/funnel filling, lenticular, layered/massive bauxite deposits occur separately in the karst platforms, gentle slopes and low-lying areas. The karst platforms and gentle slopes are conducive to surface water leaching, with strong karstification, well-developed pores, large reservoir thickness and good physical properties, but poor strata continuity. The low-lying areas have poor physical properties but relatively continuous and stable reservoirs. The gas enrichment in bauxites is jointly controlled by source rock, reservoir rock and fractures. This recognition provides geological basis for the exploration and development of natural gas in the Upper Carboniferous in the study area and similar bauxite systems.

Silica Scaling Inhibition in Water Treatment Process Using Fibrous Al2O3-Nylon 6 Adsorbents

This study describes a novel approach using fibrous Al2O3-Nylon 6 composites to induce inhibition behavior in silica scaling systems. The composite fibers were fabricated with a wet-spinning process using the coagulation of a methanolic Nylon-CaCl2 solution with Al2O3 powder after immersing the thread-like solution in water. The mesoporous nylon fibers composed of Al2O3 powders ranging from 10 to 30 wt% loading demonstrated superior adsorption capabilities to silica in water, behaving with the Freundlich model and exhibiting effective multilayer adsorption onto the Al2O3 sites embedded in the fiber. Furthermore, the composite fibers inhibited silica scaling, even at high concentrations, due to a substantially efficient reduction in soluble silica when the composite fiber was present in the system. The utilization of 15 g of composite fibers resulted in a rapid drop to approximately 30 mg/L within the initial 10 h, which is a considerable improvement compared to the 300 mg/L observed in the fiber-free control sample. Notably, the presence of an elevated fiber content exceeding 7.5 g demonstrated the complete inhibition of silica precipitation. An analysis of the pore volume using nitrogen adsorption experiments before and after silica adsorption showed that silica adsorption resulted in a significant decrease in mesoporous properties at the alumina sites. This indicated an efficient adsorption of silica onto the alumina site, effectively removing silica from the system.

Microscopic mechanism of carbon oxides formation during long-flame coal oxidation at molecular scale

Precursors of carbon oxides in coals are considered to be related to aldehyde group(–CHO) and carboxyl group (–COOH), but the way of decomposition of precursors to produce carbon oxides is not clear. Through theoretical analysis, experimental research and quantum chemical calculation at molecular scale, this paper explores the decomposition mode and products of carbon oxide precursors during coal spontaneous combustion (CSC). A programmed heating device was used to investigate the change rule of gas product concentration during the constant temperature oxidation of coals, and the microstructure of the coals was characterized by low-temperature nitrogen adsorption experiments (BET), X-ray Diffraction (XRD) and X-ray photoelectron spectrometer (XPS). The results of the study show that during coal oxidation, the inhomogeneous energy exchange between the coals and the external heat source results in the change of gas product concentration with time following two rules. BET experiments reveal that oxidation leads to the evolution of fine mesopores to macropores and an increase in the number of pores with diameters larger than 20 nm in the coals, which facilitates the transport of oxygen molecules through the pore structure. Within 200 °C, the microcrystalline structure of coals is basically unchanged, and the active structure C–C/C–H on the side chain is converted to –CHO and –COOH and then decomposed to produce carbon oxides. Quantum chemical calculation shows that the reaction energy barrier of carbonyl group and carboxyl group decomposed step by step to form carbon oxides is much smaller than that of direct decomposition, and carbon oxides and alkyl radicals can be produced even at room temperature by step decomposition. The research results provide theoretical guidance for the formation mechanism of carbon oxides during low temperature oxidation of coals.

Diagenetic characteristics and microscopic pore evolution of deep shale gas reservoirs in Longmaxi Formation, Southeastern Sichuan basin, China

The Lower Silurian Longmaxi Formation is the favorable target area for deep shale gas exploration and development in southeastern Sichuan Basin. Based on whole-rock X-ray diffraction analysis, scanning electron microscope, reservoir evolution thermal simulation experiment and nitrogen adsorption experiment, the diagenetic characteristics of deep shale reservoir in Longmaxi Formation were analyzed, and the reservoir pore evolution law was clarified. The results show that: ①The diagenetic minerals of the deep shale in the Longmaxi Formation are mainly quartz and clay minerals, with a small amount of carbonate minerals and feldspar. The primary inorganic pores are mainly controlled by mechanical compaction and cementation (quartz, carbonate, clay, pyrite). The organic pores are mainly controlled by the thermal maturity of organic matter, dissolution and later compaction. ②In the process of thermal simulation experiment, the organic pores of shale show a process of change from scratch, from small to large and then from large to small. Later, the organic matter is affected by compaction and graphitization, and the volume of micropores and mesopores begins to decrease. ③The shale pores of Longmaxi Formation have undergone several evolutionary stages. In the early stage of diagenesis, compaction caused a large number of inorganic pores to disappear. In the middle stage of diagenesis, kerogen hydrocarbon generation occupied pores, dissolution and cementation transformed pores. In the late diagenetic period, liquid hydrocarbon cracking gas and pressurization promote the development of organic pores.

Ultrahigh-Resolution Reconstruction of Shale Digital Rocks from FIB-SEM Images Using Deep Learning

Summary Accurate characterization of shale pore structures is of paramount importance in elucidating the distribution and migration mechanisms of fluids within shale rocks. However, the acquisition of high-resolution (HR) images of shale rocks is limited by the precision of the scanning equipment. Even with higher-precision devices, compromising the image field of view becomes inevitable, making it challenging to faithfully represent the actual conditions of shale. We propose a stepwise 3D super-resolution (SR) reconstruction method for shale digital rocks based on the widely used focused-ion-beam scanning electron microscope (FIB-SEM) technique. This method effectively addresses the issues of inconsistent horizontal and vertical resolutions as well as low 3D image resolution in FIB-SEM images. By adopting this approach, we significantly enhance image details and clarity, enabling successful observations of pores smaller than 10 nm within shale and laying a foundation for further pore-scale flow simulations. Furthermore, we extract the pore network model (PNM) from the SR reconstructed digital rock to analyze the pore size distribution, coordination number, and pore-throat ratio of shale samples from the Jiyang Depression. The results demonstrate a pore radius distribution in the range of 0 nm to 40 nm, which aligns with the results from nitrogen adsorption experiments. Notably, pores with radii smaller than 10 nm account for 50% of the total connected pores. The proportion of isolated pores in the SR reconstructed shale PNM is significantly reduced, with the coordination number mainly distributed between 1 and 4. The pore-throat ratio of shale ranges from 1 to 3, indicating a relatively uniform development of pores and throats. This study introduces a novel method for accurately characterizing the shale pore structure, which aids researchers in evaluating the pore size distribution and connectivity of shales.

Study on the pore evolution of Xinjiang oil shale under pyrolysis based on joint characterization of LNTA and MIP

During the in-situ exploitation of oil shale, the evolution of pore structure will affect the heat transfer medium and the transport capacity of products. In this study, using the oil shale from Jimsar region of Xinjiang, in combination with the low-temperature nitrogen adsorption experiment (LNTA) and high-pressure mercury injection experiment (MIP), the effect of temperature on evolution law of its pores during pyrolysis were analyzed according to the LNTA and MIP joint characterization results. The results show as follows: the change curve of oil shale porosity with pyrolysis final temperature in Xinjiang shows an “S” shape. The pore volume increases slightly before 300 °C, and it shows an increasing trend in the subsequent temperature range, with the mesopore volume change being the most noticeable. However, the increase slows down after 600 °C. The evolution of full-scale pores in the pyrolysis process of oil shale is reflected by the joint characterization of LNTA and MIP, which indicates that the temperature has a controlling effect on the evolution of pore, and provides basic theoretical support for how to improve the oil recovery rate of exploitation of oil shale.

Evolution characteristics of pore structure of coal under freeze-thaw cycles combined with scanning electron microscope instrument and nitrogen adsorption experiment

ABSTRACT In this paper, anthracite in Shanxi region is taken as a research object, and the pore structure of coal under different freeze-thaw times is characterized and analyzed by scanning electron microscope and nitrogen adsorption experiment. The SEM experimental results show that the micron-scale cracks on the surface of anthracite gradually connect after freeze-thaw, and the secondary crack channels are formed around the pores and air holes, so that the pores also begin to connect. Further, the quantitative information of the picture was extracted, and it was found that the surface porosity and fractal dimension of the coal sample changed significantly after three freeze-thaw cycles, which increased by 163.3% and 15.9% respectively, and increased with the increase of freeze-thaw cycles. The results of low-temperature nitrogen adsorption experiments show that the coal samples after freeze-thaw are mainly crack, and the pore structure changes from simple to complex. In addition, the maximum nitrogen adsorption capacity, specific surface area and pore volume increased by 125.7%, 69.3% and 72.6%, respectively. With the increase of freeze-thaw times, the growth rates of maximum nitrogen adsorption capacity, specific surface area and pore volume are significantly different. The results of joint characterization show that the number of pores and cracks increases to different degrees after freezing and thawing. Comparing the increase in the degree of fracturing (163.3%) with the increase in the total pore volume (30.68%), we find that the degree of change of the crack after thawing is higher than that of the pore. In this paper, the damage effect of coal samples after freezing and thawing with liquid nitrogen is investigated from an experimental point of view, which accelerates the great leap of cyclic cryogenic fracturing technology from basic theory to technical practice.

Effect of different water and organic matter content on the resistivity of loess

The pore structure and strength of loess itself will change significantly in the process of mixing organic matter, which, as the main component of solid waste at present, is of great significance for ecological vegetation restoration in loess areas. At present, the research on the internal structure and strength performance of loess through the content of organic matter is still less, this paper takes the loess mixed with different content of organic matter (0 %–6 %) and distilled water (12 %–24 %) as the object of research, and tests the electrical resistivity and pore structure of the doped organic matter loess through the LCR digital bridge test equipment and liquid nitrogen adsorption experiments. The results show that the organic matter content and water content are important factors affecting the change of resistivity of organic soil. The electrical resistivity of organic soil is correlated with its own water content and organic matter content, which is closely related to the pore type and specific surface area within the organic soil. The results of the study provide valuable references for vegetation restoration and land use and conservation strategies in ecosystems.

Facile preparation of sulfonated covalent triazine frameworks for effectively detection of six carcinogenic aromatic amines in cigarette smoke

FDA reported a HPHCs (Harmful and Potentially Harmful Constituents) list for tobacco products and tobacco smoke in 2012, which contained six carcinogenic aromatic amines (AAs). In this work, a sulfonated covalent triazine frameworks (CTF-SO3H) material was synthesized and used as a solid phase extraction (SPE) absorbent for highly effective enrichment and determination of six carcinogenic AAs in cigarette mainstream smoke (MSS), coupled with HPLC-MS/MS technique. The CTF-SO3H material was prepared with a rapid and facile method, which was superior to the general methods. The characterization with Nitrogen adsorption and desorption isotherm experiment, High resolution transmission electron microscopy (HTEM), etc, indicated that the CTF-SO3H material possessed sulfonic acid groups and abundant microporous structure. And the CTF-SO3H material showed good enrichment effect for AAs due to the synergistic effect of π-π stacking and electrostatic interactions. Limits of detection (LODs) of 6 AAs with the developed method were in the range of 0.01–0.11 ng cig−1. Recoveries of 6 AAs were between 80.40% and 106.00%, while the intra-day and inter-day precisions were good (i.e. RSDintra ≤ 6.40%, RSDinter ≤ 9.90%). Commercial cigarette MSS samples were analyzed with the developed method, and a commercial cation exchange SPE column was chosen for comparison. Results obtained by two methods showed a good consistency. However, the CTF-SO3H material needed less dosage, even could be reused for 4 times. Thus, the developed method not only showed high enrichment efficiency, but also was economical.

Temperature dependence of aggregation behavior and dye adsorption of poly(N-isopropylacrylamide) hydrogel/mesoporous silica composites

This study aimed to synthesize mesoporous silica (MS) with various amounts of poly(N-isopropylacrylamide) (PNIPAM) hydrogel using two procedures and investigate the influence of the PNIPAM hydrogel on the aggregation performance of the synthesized PNIPAM hydrogel/MS composite at temperatures above the lower critical solution temperature (LCST) of PNIPAM (i.e., 32 °C) and adsorption behavior of the composite below the LCST. To rapidly recover an MS adsorbent from water, we synthesized the MS coated with hydrogel composed of PNIPAM as a temperature-responsive polymer and N, N′-methylenebisacrylamide (BIS) as a cross-linker. We characterized our samples using ultraviolet-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and desorption experiment, and thermogravimetric analysis (TG). Using TG, we found that the amount of immobilized PNIPAM hydrogel could vary from 6.6 to 57.5 wt% by changing the amount of BIS and the immobilization procedure. The XRD patterns revealed that the PNIPAM hydrogel coating had slight influence on the MS structure. The higher the amount of PNIPAM hydrogel in the composite, the faster the turbidity rate decreased based on the turbidity measurement of the supernatant solution during the PNIPAM hydrogel/MS composite sedimentation test in water at 50 °C. The coating by PNIPAM hydrogel of the MS surface only slightly affected the amount of methyl orange adsorbed at 30 °C.

A molecularly imprinted polymer monolithic column with dual template and bifunctional monomers for selective extraction and simultaneous determination of eight phenolics from polycarbonate cups

A molecularly imprinted polymer (MIP) monolithic column was prepared in situ in a pipette tip using phenol and bisphenol A as dual templates, 4-vinyl pyridine and β-cyclodextrin as bifunctional monomers. It was used for the selective and simultaneous solid phase extraction of eight phenolics, including phenol, m-cresol, p-tert-butylphenol, bisphenol A, bisphenol B, bisphenol E, bisphenol Z, and bisphenol AP. The MIP monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and nitrogen adsorption experiment. The results of selective adsorption experiments showed that the MIP monolithic column can selective recognize the phenolics and have excellent adsorption property. The imprinting factor for bisphenol A can be as high as 4.31, and the maximum adsorption capacity for bisphenol Z can reach 201.66 mg g−1. Under the optimal extraction conditions, a selective and simultaneous extraction and determination method for eight phenolics was established based on the MIP monolithic column and high-performance liquid chromatography with ultraviolet detection. The linear ranges (LRs) of the eight phenolics were 0.5–200 μg L−1, the limits of quantification (LOQs) and detection (LODs) were 0.5–2.0 μg L−1 and 0.15–0.67 μg L−1. The method was applied to detect the migration quantity of the eight phenolics from polycarbonate cups and had satisfactory recovery. The method has the advantages of simple synthesis, short extraction time, as well as good repeatability and reproducibility, which provides a sensitive and reliable strategy for extracting and detecting phenolics from food contact material.

Effects of Supercritical CO2 on the Pore Structure Complexity of High-Rank Coal with Water Participation and the Implications for CO2 ECBM.

To reveal how mineral changes affect a coal pore structure in the presence of water, an autoclave was used to carry out the supercritical CO2 (ScCO2)-H2O-coal interaction process. To reveal the changes in pore complexity, mercury intrusion capillary pressure (MICP), low-pressure nitrogen adsorption, CO2 adsorption, and field emission scanning electron microscopy (FESEM) experiments were combined with fractal theory. The experimental data of MICP show that the MICP data are meaningful only for the pore fractal dimension with pore sizes >150 nm. Therefore, the pores were classified into the classes >150, 2-150, and <2 nm. The results show that the pore volume and specific surface area of the coal increased significantly after the reaction. ScCO2-H2O can cause the formation of many new pores and fractures in the coal. The presence of H2O may increase the potential for the injection of CO2 into the coal seam. The complete dissolution of calcite surfaces caused a significant increase in the pore volume and specific surface area of the pores >150 nm. The morphologies of these pores are controlled by the morphologies of the complete dissolution carbonate particles. The pore morphologies were relatively uniform, and the fractal dimensions decreased. However, the incomplete dissolution of calcite leads to irregular variations in the morphologies for the pores in the 2-150 nm pore size range. The pore morphologies that are produced by incompletely dissolved calcite particles are more complex, which increases the fractal dimensions after the reaction. The fractal dimensions of the pores <2 nm decreased after the reaction, indicating that the newly generated micropores were more uniform and had regular pore morphologies.

Insight into the application of magnetic molecularly imprinted polymers in soil-washing effluent: Selective removal of 4,4′-dibromodiphenyl ether, high adaptivity of material and efficient recovery of eluent

Soil washing techniques can effectively remove soil polybrominated diphenyl ethers (PBDEs), but further removal of PBDEs from washing effluent is disrupted by environmental factors and coexisting organic matter. Hence, this work prepared novel magnetic molecularly imprinted polymers (MMIPs) to selectively remove PBDEs in soil washing effluent and recycling surfactants, with Fe3O4 nanoparticles as the magnetic core, methacrylic acid (MAA) as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Later, the prepared MMIPs were applied to adsorb 4,4′-dibromodiphenyl ether (BDE-15) in Triton X-100 soil-washing effluent and characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), nitrogen adsorption and desorption experiments. According to our observations, BDE-15 equilibrium adsorptions on dummy-template magnetic molecularly imprinted adsorbent (D-MMIP, 4-bromo-4′-hydroxyl biphenyl as template) and part-template magnetic molecularly imprinted adsorbent (P-MMIP, toluene as template) were reached within 40 min, and their equilibrium adsorption capacities were 164.54 μmol/g and 145.55 μmol/g, respectively, with imprinted factor α > 2.03, selectivity factor β > 2.14, and selectivity S > 18.05. MMIPs exhibited good adaptability to pH, temperature, and cosolvent. Our Triton X-100 recovery rate reached as high as 99.9%, and MMIPs maintained a more than 95% adsorption capacity after being recycled five times. Our results offer a novel approach to selectively remove PBDEs in soil-washing effluent, with efficient recovery of surfactants and adsorbents in soil-washing effluent.

Microstructure Study of High-Rank Coal in an Alkaline Solution at the Chengzhuang Mine.

To study the adsorption performance of coal bodies after alkaline solution erosion and the microscopic mechanism of alkali erosion on coal bodies, isothermal adsorption experiments at different pH values and with different numbers of soaking days were conducted on high-order coal bodies from the Chengzhuang mine. The results showed that the adsorption capacity of the coal bodies after alkali leaching was improved compared to that of the original coal, all of which was in accordance with the Langmuir equation. The unit adsorption capacity of coal samples increased gradually with an increase in the number of soaking days and solution pH, reaching the maximum at pH 13 and eight soaking days. The adsorption constant a of the coal sample was positively correlated with the pH, and the number of soaking days was a power exponential function; the adsorption constant b increased gradually with an increase in the pH of the solution and increased first and then decreased with an increase in the number of soaking days. The change in the adsorption of coal samples occurs because the alkaline solution reacts with the minerals in the coal as well as the mineral ions, and the resulting complex gels and precipitates block the pore channels of the coal body, which in turn inhibits the adsorption of gases. The presence of Na, Mg, Al, Si, Ca, Fe, and other elemental compounds detected in the generated sediments verified the mechanism of alkaline solution erosion. The changes in the microscopic pore structure of the coal body were quantified by low-temperature liquid nitrogen adsorption experiments. The small and medium pore volumes of the coal samples reached the maximum values at pH 13 and with eight soaking days, which is in agreement with the conclusion of optimal alkali modification.

Effect of water immersion on pore structure of bituminous coal with different metamorphic degrees

It is important to understand the disaster-causing mechanism of dried water-immersed coal by investigating the influence of water immersion on the coal pore structure. In this study, low-temperature nitrogen adsorption experiments of eight bituminous coals with different metamorphic degrees and their dried water-immersed coals were carried out to analyze the adsorption/desorption mechanism and investigate the effects of water immersion on the pore shape, pore-structure parameters, and fractal dimension of coal. The results showed that adsorption of nitrogen on coal mainly includes micropore filling, monolayer adsorption, multilayer adsorption, and capillary condensation. The pores of coal were a continuous system from nanometer pores to relatively unlimited size pores. Water immersion did not significantly affect the pore shape of the coal, decreased the specific surface area and adsorption capacity, and increased the total pore volume and average pore diameter. It had the greatest effect on the average pore size of moderately metamorphosed coals, which may accelerate the oxidation process of coal and aggravate gas emission. The fractal results showed that water immersion reduced the surface fractal dimension of higher and lower metamorphic coal, while it increased that of moderately metamorphic coal, and it had the opposite effect on the structural fractal dimension.

Effect of bamboo powder surface treatment on performance of asphalt binder

For expanding the application field of bamboo and improving the utilization rate of bamboo, the effect of bamboo powder (BP) treated by NaOH on the asphalt binder’s properties was discussed on the basis of previous study on the rheological property of bamboo powder modified asphalt at high temperature. The specific surface area, pore size distribution and pore structure of NaOH treated BP were analyzed by nitrogen adsorption experiment, and its micro morphology was explained by SEM. The high temperature stability, low temperature ductility, shear deformation resistance and rut resistance of BP asphalt binder were analyzed by the softening point, the ductility, the viscosity and dynamic shear rheological test. The results showed that under the treated by NaOH, the BP epidermis produced lamellar peeling, increased the specific surface area, the surface morphology was rougher, effectively improve the surface infiltration and physical adsorption capacity of BP and the asphalt binder. Both NaOH concentration and BP content increased would play positive roles on the asphalt binder’s properties, including the high temperature stability and shear deformation resistance. But the concentration and proportion should be moderate. It is suggested that 10% of BP treated with 2.5 mol/L NaOH concentration can obtain better performance of asphalt binder. By turning waste into treasure, the effective utilization of bamboo leftovers, which is a green environmental protection material, is realized, and the asphalt binder’s properties is significantly improved under the condition of simple process and low production cost.

Thermo-electro dually activated carbon cloth as cathode material for aqueous hybrid zinc ion supercapacitor with ultrahigh stability and dramatically enhanced areal capacitance

The facile and low-cost technology for the fabrication of high-performance electrode material for supercapacitors is very important for green energy storage. Herein, the commercial carbon cloth (CC) with poor capacitance is subjected to thermal treatment at 430°C, followed by a potentiostatic oxidation at a constant potential of 2 V. Through the thermal activation process, the capacitance is increased to 1310 mF cm−2, and further enhanced to 2421 mF cm−2 after the additional potentiostatic activation. Nitrogen adsorption experiment and X-ray photoelectron spectroscopy analysis show that the prominent increase in specific surface area upon thermal-activation and the formation of oxygen-containing groups after electrochemical-activation are responsible for the greatly improved capacitive properties. The aqueous hybrid zinc ion supercapacitor (HZSC) constructed using the thermal-electro dually activated CCs cathode and Zn plate anode shows a high energy density of 1.21 mWh cm−2 at a power density of 4.75 mW cm−2. The HZSC displays superior long period stability with 94.65% capacitance retention after 8000 galvanostatic charge-discharge cycles. This work proposes a facile route to transform commercial carbon cloths into high performance self-standing cathode for the aqueous HZSCs, which will have noticeable effect on energy storage technology due to its stability, low-cost, environmental friendliness and safety.