The surface area and pore volume of carbonaceous materials, which are commonly determined by N2 and/or CO2 gas-physisorption, are important parameters when describing environmental processes such as ...adsorption. Their measurement requires prior degassing of samples, which can change the nature of the material. Current guidelines for biochar characterization recommend different degassing temperatures. To investigate how degassing temperatures affect gas-physisorption we systematically degassed a range of materials (four biochars, carbon nanotubes, and Al2O3 reference material) at different temperatures (105, 150, 200, 250 and 300°C; for ≥14h each). Degassing temperatures had no effect on Al2O3 or carbon nanotubes but the measured surface areas and pore volumes of biochars increased by up to 300% with degassing temperature. An equation is presented for predicting surface area obtained at different degassing temperatures. Elemental analysis and results from sorption batch experiments suggest that surface area and pore volume may increase as biochar components volatilize during degassing. Our results showed that degassing temperatures change material properties and influence gas-physisorption measurements, and therefore need to be standardized. These results may also apply to the characterization of other complex materials, including carbon nanotubes coated with natural organic matter and fouled activated carbon.
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•Specific surface area and pore volume increase with degassing temperature.•Upon degassing, non-carbonized organic fractions in the biochar volatilize.•Standardization of degassing protocols is urgently needed in the biochar community.•A simple equation is presented to make results from different studies more comparable.
Porous carbon spheres (PCS) with different specific surface areas and porous structures were prepared by templated self-assembly method. The as-prepared PCS had uniform radically distributed ...channels, single cavity and dispersed dendritic pore structures respectively. The whole blood clotting time tests showed the good hemostatic properties of PCS, even better than Celox. It's probably the specific surface area made the difference over the hemostatic performance of PCS. The possible reason is that the higher specific surface area can increase the contact area between PCS and blood, promote blood coagulation rapidly. And the oxygen polar functional groups on the surface of PCS can rapidly stimulate platelets and red blood cells when in contact with blood. Both of the hemolysis rate and cell viability experiments proved that PCS had good biocompatibility. The hemostatic effect of PCS in vivo were preliminary validated on the mouse tail-cutting model and the rabbit liver injury model, and all PCS could efficiently control the caudal and hepatic hemorrhage. Especially, PCSF127 with a pore size of 3 nm and specific surface area of 335 m2 g−1 showed the best hemostatic efficiency, and it was expected to be an ideal candidate for rapid hemostasis in the battlefield or pre-hospital.
Porous carbon spheres with different pore structures and specific surface areas were prepared by templated self-assembly synthesis method. The negative charges carried by the porous carbon spheres activate coagulation factor FXII to trigger a coagulation cascade reaction to complete rapid hemostasis, and the hydroxyl groups on the surfaces, as oxygen polar groups, can rapidly stimulate erythrocytes and platelets when contacting with blood, thereby having a good application prospect in the fields of rapid hemostasis and wound care. Display omitted
•Porous carbon spheres (PCS) were prepared with templated self-assembly.•The microstructure made the difference over the hemostatic performance of PCS.•PCS could efficiently control the caudal and hepatic hemorrhage.
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•Conventional surface area calculations of biochars based on N2 can be unreliable.•N2 induced adsorption stress artificially enlarges the surface area of certain biochars.•The ...Brunauer-Emmett-Teller method enhances errors from N2 adsorption measurement.•Pore specific methods enable a reliable adjustment of the surface area calculation.•A modified calculation method is proposed to ensure comparability between biochars.
A large specific surface area is one of the structural characteristics which makes biochar a promising material for novel applications in agriculture and environmental management. However, the high complexity and heterogeneity of biochar’s physical and chemical structure can render routine surface area measurements unreliable. In this study, N2 and CO2 characterization of twelve biochars from three feedstocks with production temperatures ranging from 400 °C to 900 °C were used to evaluate materials with varying structural properties. The results indicate that the frequently reported peak in the surface area of biochars around 650 °C is an artefact of N2 measurements and not confirmed by CO2 analysis. Contradicting results indicate an influence of the structural rigidity of biochar on N2 measurements due to pore deformation in certain biochars. Pore non-specific calculation models like the Brunauer-Emmett-Teller method do not allow for adjustments to these changes. Instead, the use of a pore specific model and the exclusion of pores smaller than 1.47 nm was found to achieve more representative results. The proposed calculation was validated on an external dataset to highlight the applicability of the method. Our results provide novel insights for understanding the structural evolution of biochar related to production temperature.
In this article, we have synthesized carbon-coated cobalt oxide nanoparticles (NPs) and their nanocomposite with reduced graphene oxide (C@Co3O4/r-GO) via chemical and ultrasonication techniques. The ...observed higher electrical conductivity (1.4 × 10−3 S/m) of the nanocomposite than the pristine NPs (1.9 × 10−8 S/m) was due to the combined effect of the carbon-coating and r-GO nanosheets. The higher specific surface area (118 m2/g) of the nanocomposite was due to the relived agglomeration of the NPs via the carbon-coating and r-GO matrix. The nanocomposite based electrode shows exceptional gravimetric capacitance of 674 F/g at 1 A/g and loses just 18% of its initial capacitance after 103 charges/discharge cycles. The superior electrochemical performance of the nanocomposite was due to its higher surface area and synergistic improvements between carbon-coated NPs and highly conductive r-GO nanosheets. In the nanocomposite, the r-GO nanosheets play a double role to increase the energy storage properties. For example, the r-GO sheets acted as a capacitive supplement as well as a conductive matrix for a speedy redox reaction. Highly conductive nanocomposite also showed lower charge transfer resistance (Rct ~ 12.78 Ω) during the electrochemical impedance spectroscopic (EIS) tests that further facilitated the redox reaction to achieve higher pseudocapacitance. The observed electrical and electrochemical results demonstrate the potential of the C@Co3O4/r-GO nanocomposite for hybrid supercapacitors.
Water is considered ubiquitous within the shale reservoirs and mainly stored in the hydrophilic clay minerals. The water distribution characteristics and its effect on pore structure are important ...for the gas-in-place of shale systems. In this work, water vapor adsorption on montmorillonite (Mt), kaolinite (Kaol) and illite (Il) were performed to investigate the behaviors of water adsorption on shale clay. Subsequently, the moisture-equilibrated samples were conducted with N2 gas-adsorption techniques to investigate the effect of adsorbed water on pore structure characteristics, such as apparent pore size distribution (APSD), N2 BET specific surface area (N2-BET SSA) and pore volume (PV). The results show that the water uptake isotherms of our samples have the sigmoidal-shaped profiles and GAB model provides a good fit for the adsorption behavior. In addition, The APSD curves under different relative humidity (RH) conditions have validated the condensation effect and indicated that the small pores (approximately smaller than 5nm) are blocked by the capillary water and will disappear on the APSD curves at RH of 98% while the large nanopores (>5nm) are covered with water film, these effects will lead dramatically decrease of N2-BET SSA. Taking Mt and Il samples as the examples, the N2-BET SSA has declined to 33.51% and 33.66% compared with the dry conditions when Sw approaches to 50%. Meanwhile, these effects also indicate that the gas storage for clay minerals is massively overestimating under dry condition, the contribution to methane adsorption might be negligible in the actual shale reservoir.
•Water adsorption isotherms were applied to investigate the adsorption behaviors of water vapor on clay minerals.•APSD curves were measured with N2 gas-adsorption techniques to validate capillary condensation in small pores.•The water distribution is visually presented by comparing the APSD curves between dry and moist condition.•The impact of water on pore structure characteristics and methane adsorption capacity are analyzed.
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•The dissolution of lurasidone hydrochloride (LH) tablets containing different grades mannitol with similar particle size varied unexpectedly.•The key property of mannitol affecting ...tablet dissolving is specific surface area (SSA).•By affecting drug-drug bonding, SSA, rather than particle size, of mannitol affects the percolation threshold state of the tablet.•Increasing SSA of excipient: a promising strategy for development novel excipient grade aiming at improving drug dissolution functionality.
The dissolution behavior of tablets, particularly those containing poorly water-soluble drugs, is a critical factor in determining their absorption and therapeutic efficacy. Traditionally, the particle size of excipients has been considered a key property affecting tablet dissolution. However, lurasidone hydrochloride (LH) tablets prepared by similar particle size mannitol, namely M200 (D90 = 209.68 ± 1.42 μm) and 160C (D90 = 195.38 ± 6.87 μm), exhibiting significant differences in their dissolution behavior. In order to find the fundamental influential factors of mannitol influencing the dissolution of LH tablets, the properties (particle size, water content, true density, bulk density, tapped density, specific surface area, circularity, surface free energy, mechanical properties and flowability) of five grades mannitol including M200 and 160C were investigated. Principal component analysis (PCA) was used to establish a relationship between mannitol properties and the dissolution behavior of LH. The results demonstrated that specific surface area (SSA) emerged as the key property influencing the dissolution of LH tablets. Moreover, our investigation based on the percolation theory provided further insights that the SSA of mannitol influences the probability of LH-LH bonding and LH infinite cluster formation, resulting in the different percolation threshold states, then led to different dissolution behaviors. Importantly, it is worth noting that these findings do not invalidate previous conclusions, as reducing particle size generally increases SSA, thereby affecting the percolation threshold and dissolution behavior of LH. Instead, this study provides a deeper understanding of the underlying role played by excipient SSA in the dissolution of drug tablets. This study provides valuable guidance for the development of novel excipients aimed at improving drug dissolution functionality.
Coal gangue is a kind of solid waste produced in the process of coal mining and washing. Its silicon aluminum silicon aluminum oxide content is high, respectively, which are suitable for resource ...utilization as raw materials for Si–Al molecular sieving. In this paper, a novel, simple, low-cost, and environmentally friendly process was carried out to prepare ZSM-5 zeolite by solvent free method after calcination, acid leaching, and alkali melting. The obtained samples were characterized by Energy Dispersive Spectrometer (EDS), Inductively Coupled Plasma (ICP), Thermo-gravimetry Analysis (TG), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectrometer (FTIR) X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and N2 adsorption isotherm. The characteristics of the raw materials and the adsorption mechanism of the prepared samples were characterized. Through a series of pretreatment such as calcined acid leaching and alkali melting of the raw materials, the silicon-aluminum ratio of the sample reaches 1.749, and the maximum specific surface area of the sample can reach 252.59 m2/g. The obtained samples were used to adsorb heavy metal ions and methylene blue solution, and the removal rate of lead ions and methylene blue solution was more than 95%. The theoretical maximum adsorption capacity of Pb ion, methylene blue solution and copper ion can reach 232.56 mg/g and 118.34 mg/g. The adsorption process is mainly chemical adsorption. The product could be suitable for removing both heavy metal ions and cationic dyes from the wastewater and had broad application prospects.
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•The raw coal gangue was pretreated by calcination, acid leaching and alkali melting to concentrate silicon to improve the silicon-aluminum ratio.•ZSM-5 molecular sieve was prepared by solventless grinding method, which is an energy saving and environmental protection method.•The adsorption of heavy metal ions and methylene blue molecules in samples is mainly chemisorption, and the adsorption process is stable, and the cyclic adsorption effect is good.
Understanding the relationship between pores and the chemical structures of char can help analyze the interaction between chemical reactions and mass transfer during coal gasification. In this paper, ...chars prepared from Naomaohu coal by a drop tube furnace and a fixed bed reactor at 700 ℃, respectively, were gasified in CO2 by the drop tube furnace at 900 ∼ 1000 ℃ to obtain gasified char samples with different pores and chemical structures. The structure characterization results of this gasified char samples indicate that the mesopore-specific surface area increases exponentially from 146.8 to 409.3 m2/g with the decrease of AG/AOther (the ratio of the peak G area to the sum of other peaks except for peak G and peak D in the Raman spectrum) from 0.68 to 0.45, and thus an exponential correlation was proposed to predict this trend. The specific surface area of the pores 0.44–0.60 nm increases with increasing aliphatic carbon content and the specific surface area is 110.5 and 260.2 m2/g when the aliphatic carbon content is 0.07 and 0.17, respectively, while the specific surface area of the pores of 0.72–0.98 nm increases with increasing substituent content (including aliphatic carbon and carbon bonded with oxygen atoms), and the specific surface area is 28.3 and 51.6 m2/g when the substituent content is 0.17 and 0.43, respectively.
•A series of CoS2@MOF-derived hollow carbon spheres were prepared by solvothermal method.•The overpotential of 232 mV at a current density of 10 mA cm−2 was achieved by CoS2–600.•The synergistic ...effect between CoS2 and hollow carbon spheres was discussed.
Electrocatalytic water splitting is a promising method for producing high-purity hydrogen. Metal-organic frameworks (MOFs) have recently emerged as unique electrocatalysts for overall water splitting. With their large specific surface area, high porosity, adjustable composition, and diversified structure, MOFs are widely used as precursors for preparing non-noble metal-based electrocatalysts. This paper presents the preparation of CoS2 particles loaded on carbon spheres derived from Co-MOF microspheres by calcination and sulfide reaction with sulfur. The optimized CoS2–600 particles demonstrate excellent OER and HER electrocatalytic performance in 1 M KOH solution. The MOF does not act as a catalyst, but rather adjusts the phase of the catalytic active material, changes the intermediate adsorbent, and increases the number of catalytic sites. The morphology and physical phases of the CoS2–600 particles were analyzed after cycling to identify the real active components during hydrogen and oxygen evolution.
In this paper, the pore structure and fractal characteristics of coal under liquid nitrogen cold soaking are tested for different coal qualities of anthracite, bituminous coal and lignite, and the ...variation patterns of BET specific surface area, BJH total hole and adsorption pore specific surface area with liquid nitrogen cold soaking times are studied. Among these coal samples, it is found that the raw bituminous coal has the most internal micropore content and the largest adsorption space for gas, followed by anthracite, and lignite is the last. After one time liquid nitrogen cold soaking, the increase of adsorption and percolation pore contents of each coal sample in the order of: anthracite > lignite > bituminous coal; and with the increase of liquid nitrogen cold soaking times, the internal pore size and number of pores of the three coal samples gradually increases, but the specific surface area of adsorption pores decreases. The reduction amplitude of the specific surface area of coal adsorption pores by one time liquid nitrogen cold soaking gradually increases with the increase of metamorphism. With the increase of liquid nitrogen cold soaking times, the average pore size, total BJH hole and percolation hole of each coal sample increases, while the BET specific surface area and adsorption pore specific surface area decreases gradually. The fractal dimension D1 of each coal sample increases linearly with the increase of liquid nitrogen cold soaking times, and the variation of D2 has an opposite trend. The results of this study can provide theoretical and experimental support for further application of liquid nitrogen to increase the permeability of coal seams.
•Pore structure and fractal characteristics of coal under the liquid nitrogen cold soaking are tested.•Liquid nitrogen cold soaking could improve the coal pore connectivity.•Fractal dimension D1 of coal increases linearly with the liquid nitrogen cold soaking number.
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