Well-developed Porous Structure Research Articles

Elimination of hydrogen bonds in cellulose enables high-performance disordered carbon anode in sodium-ion batteries

Pre-oxidation remains an advantageous method to regulate the cross-linking structure of cellulose to prepare an increasingly disordered hard carbon applied in sodium-ion batteries. However, it is ambiguous how the introduction of oxygen affects the changes in the molecular structure of cellulose as well as the micro-structure of hard carbon. We herein systematically investigate the effect of air pre-oxidation on the crystallinity and cross-linking structure of cellulose macro-molecules by controlling the degree of oxidation. The findings indicate that the introduction of air can break the hydrogen bonding network of cellulose in advance and release a large number of reactive hydroxyl groups on the surface to be oxidized to form ether and ester cross-linking bonds. Ether bonds can transversely cross-link and extend the carbon layer and the bent carbon layers enclose a well-developed connective pore structure. Additionally, the breakage of oxygen-containing functional groups leads to the escape of large amounts of oxygen-containing gases to etch out more open pore structures with large pore sizes. Benefiting from these advantages, the prepared hard carbon possesses a specific capacity of 335 mAh·g‒1 and 89% of initial coulombic efficiency at 30 mA·g‒1 by pre-oxidating at 300°C for 12 h.

Graphenic materials prepared from magnesium ions doping cellulose and its application in electrochemical detection of adenine and guanine

Graphenic materials of high quality are in high-demand. In this study, a method is proposed for the synthesis of graphenic materials by the pyrolysis of cellulose materials. Cellulose materials were oxidized and doped with magnesium prior to pyrolysis, which improved the graphitization efficiency significantly. The obtained graphenic materials, exhibiting a well-developed porous structure, high specific surface area, were employed for the fabrication of a composite electrode. The composite electrode was employed for the simultaneously detection of adenine (AE) and guanine (GA) with excellent performance in the electrocatalytic oxidation response. Various electrochemical tests were carried out to optimized the detection of AE and GA. Under the optimized conditions, the simultaneous quantification of GA and AE is achieved from 1 – 100 μM with detection limits from 0.4 – 0.6 μM. This study offers a promising alternative for the synthesis of graphenic materials of high quality.

Tuning of Particle Size of Zeolitic Imidazolate Framework-7 via Rapid Synthesis Duration for CH4 Adsorption

In this work, zeolite imidazolate framework-7 (ZIF-7) nanoparticles are synthesized via a solvothermal method and rapid synthesis durations of 1 h and 3 h. The effect of the synthesis duration on the structural properties of ZIF-7 was characterized by XRD and FESEM analyses. Subsequently, CH4 single gas adsorption over ZIF-7 nanoparticles was examined using the volumetric method at room temperature and pressure ranging from 2 to 9 bar. The results showed that the synthesized ZIF-7 adsorbents were highly crystalline with a well-defined and homogeneous particle size distribution of 50–60 nm. It was found that increasing the synthesis duration from 1 h to 3 h did not amend the structure and morphology of the resultant samples significantly, mainly due to the short synthesis duration. Meanwhile, the CH4 adsorbed by ZIF-7 nanoparticles increased with rising pressure for both samples, and the ZIF-7 nanoparticles synthesized at 3 h showed a greater adsorption capacity than that of 1 h, mainly due to its higher crystallinity and well-developed pore structure. The ZIF-7 synthesized at 3 h demonstrated an adsorption capacity up to 2.2 mol/kg, which was higher than those values reported in the literature for micron-sized ZIF-7 samples. The CH4 gas adsorption behavior of ZIF-7 nanoparticles synthesized at 1 h and 3 h were well predicted by the Langmuir isotherm model, with coefficients of determination, R2, of 0.9994 and 0.9982, respectively.

Amine-impregnated elastic carbon nanofiber aerogel templated by bacterial cellulose for CO2 adsorption and separation

Carbon aerogel has become a promising electrode material for CO2 capture and capacitor due to its large specific surface area, well-developed pore structure, adjustable porosity and ultra-high specific power. However, most of the carbon-based materials suffer from poor mechanical properties, low recycling efficiency, and low adsorption capacity, making it difficult to be put into industrial applications on a large scale. Bacterial cellulose (BC) has an ultra-fine reticular structure, a modulus of elasticity that is several to more than ten times that of typical plant fibers, and high tensile strength. In this paper, BC was treated by unidirectional freeze-drying method, and the aerogels with ordered honeycomb pore structure were constructed by unidirectional growth of ice crystals, and the pyrolytic chemical properties of BC were adjusted by using (NH4)2SO4, which effectively prevented the shrinkage and deformation of materials during carbonization, and successfully prepared elastic nanocarbon fiber aerogels. At the same time, the introduction of (NH4)2SO4 made the material realize N doping in the carbonization process, providing more adsorption sites, which was conducive to the adsorption of CO2. Finally, the carbon fiber nanoaerogel was modified by TEPA to further improve its adsorption selectivity for CO2. The prepared elastic carbon nanofiber aerogel (CBCNT) has high CO2 adsorption performance and high selectivity, and its CO2 capture capacity is up to 4.88 mmol/g. At the same time, its capacitance also reached 246F/g.

Adsorption of dibenzofuran by modified biochar derived from microwave gasification: Impact factors and adsorption mechanism

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to the human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating or microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques, including BET, X-ray CT, SEM-EDS, FTIR, and XPS, are performed to identify the DBF adsorption mechanism on the biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. The higher porosity (16.94 %) and lower mineral content (1.75 %) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by the HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11 %) > KOH-modified CSC (77.14 %) > unmodified CSC (49.11 %) > unmodified OC (39.70 %) > HNO3-modified CSC (36.09 %). The adsorption mechanisms of DBF on the gasified biochar encompass the pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously.

Co-adsorption performance and mechanism of ammonium and phosphate by iron-modified biochar in water

To recover nitrogen and phosphorus from water bodies and reduce their potential risk of causing eutrophication, high-temperature pyrolysis-produced biochar (HBC) modified by ferric chloride (Fe-HBC) was adopted to investigate its surface modification on the co-adsorption performance of nitrogen and phosphate. In comparison to HBC, Fe-HBC exhibited superior specific surface area, well-developed pore structure, and enriched surface functional groups while successfully loading Fe2+ and Fe3+. It has been determined that the co-adsorption mechanism of ammonium and phosphate by Fe-HBC involves a combination of pore filling, ion exchange, functional group coordination, electrostatic attraction, and coprecipitation. The results from the batch adsorption experiments indicate that the ammonium adsorption capacities for Fe-HBC1, Fe-HBC2, and Fe-HBC3 were 10.59 mg/g, 10.38 mg/g, and 7.59 mg/g, respectively, while the phosphate adsorption capacities were 13.46 mg/g, 10.46 mg/g, and 15.22 mg/g, respectively. The results of the column adsorption experiments showed that too high or too low biochar percentage and flow rate were not conducive to improving the adsorption capacity of the adsorption column, and the maximum adsorption capacity of the adsorption column was achieved at a biochar percentage of 1 % and a flow rate of 1 mL/min. This study demonstrates the potential of this iron-modified biochar derived from agricultural wastes for practical application in the removal of ammonium and phosphate from wastewater.

Combining SiO2 NPs with biochar: a novel composite for enhanced cadmium removal from wastewater and alleviation of soil cadmium stress.

Cadmium (Cd) pollution in water and soil seriously threatens human health. Biochar and nanomaterials have high potential for solving the cadmium pollution problem due to their abundant pores and high specific surface area. Here, the preparation of the composite material SiO2NPs@BC (SBC) using SiO2 NPs (SN) and silkworm excrement biochar (BC) is described, along with its application in the remediation of cadmium-contaminated water and soil. Characterization experiments (SEM&EDS, BET, FTIR, XRD, and XPS) demonstrated that SiO2NPs@BC has a high specific surface area (46.5767m2/g), a well-developed pore structure (0.608375cm3/g), and abundant surface functional groups (Si-C, Si-O, Si-O-Si), providing active sites for the adsorption of Cd. Batch adsorption experiments in water showed that the adsorption capacity of SBC is higher than that of biochar (BC) and SN, with a maximum Langmuir adsorption capacity of 141.99mg/g. After five adsorption cycles, the removal rate of SBC was 73.04%, significantly higher than the 64.97% obtained for BC. The application of SBC not only improved the soil physicochemical properties by increasing the soil pH, the cation exchange capacity, and the soil organic matter content but also by reducing the amount of DTPA-Cd (24.6%) and the plant bioconcentration factor (28.28%) in the soil, converting Cd into more stable fractions (Red-Cd, Ox-Cd). Based on the results, SBC can effectively reduce Cd pollution.

Targeted construction of porous biochar with well-developed pore structure for high-performance CO2 adsorption

Targeted construction of porous biochar is vital for the development of carbon capture. In this paper, we use the KOH chemical activation with walnut shell as raw material, to investigate the effects of the preparation process on the targeted construction of CO2 adsorbents. We have revealed the vital factors influencing CO2 adsorption and developed the design strategy for porous biochar under different application conditions. The specific surface area can up to 2115 m2 g−1, and the microporosity can up to 95.5 %. The CO2 adsorption capacities are 6.75 mmol g−1 and 17.59 mmol g−1 at 0°C, 1 bar and 10 bar. Meanwhile, the heat of adsorption ranges from 18 to 30 kJ mol−1. In addition, the sample exhibits outstanding adsorption kinetics, good adsorption selectivity, and its CO2 adsorption capacity fluctuates within 5 % after 10 adsorption-desorption cycles. Therefore, the strategy developed in this paper can be applied to the high-performance adsorption of CO2 under different conditions.

Investigation of high internal phase water-in-oil emulsion on coal gasification fine slag flotation decarburization and its oil saving mechanism

Froth flotation stands as the preferred technique for the separation of charcoal and ash from coal gasification fine slag (CGFS). However, the presence of a well-developed pore structure and an abundance of oxygen-containing functional groups on the surface of residual charcoal necessitates the use of substantial dosage of collectors during the flotation of CGFS. To address this, a high internal phase water-in-oil (HIP W/O) emulsion, with an internal phase water volume fraction of 85 %, was formulated for the flotation decarburization of CGFS, with the objective of reducing the collector dosage. The outcomes of flotation tests demonstrated that at dosages of 50 kg/t for kerosene and 15.04 kg/t for the organic liquid of the HIP W/O emulsion, both were capable of yielding tailings with an ash content exceeding 95 %. The results from Cryo-SEM and viscosity tests suggest that the high viscosity characteristics of the HIP W/O emulsion are primarily attributed to the compact arrangement of emulsion droplets and the active influence of emulsifiers at the oil–water interface. High-speed camera observations revealed that the HIP W/O emulsion droplets exhibited a tendency to disperse into bar-shaped flocs with larger particle sizes in water. This particular dispersion morphology is advantageous for enhancing the oil agglomeration flotation mechanism within the flotation decarburization process of CGFS. LF-NMR tests have further substantiated that the emulsion droplets are not readily absorbed by the microporous structure of the residual charcoal within the CGFS. Wettability tests and FTIR analyses have demonstrated that the hydrophobic modification of the residual charcoal surface, achieved through the HIP W/O emulsion, markedly surpasses that of conventional kerosene. The combination of these results indicates that the use of HIP W/O emulsion in the flotation decarbonization process of CGFS offers multiple benefits. It not only significantly reduces the dosage of organic collectors required, but also enhances the economic efficiency and effectiveness of the flotation process, presenting a novel reagent option for the decarbonization of CGFS.

Synthesis of mixed-base active material from drilling fluid solid waste and biomass for oil wastewater adsorption and its mechanism

To address the issues of high energy consumption, high cost and the risk of secondary pollution in drilling fluid solid waste treatment methods, this study prepared a mixed-based active material using drilling fluid solid waste and biomass materials as raw materials. The mixed-based active material is characterized by its abundant pore structure and high pore volume, demonstrating excellent adsorption performance for heavy metal ions and residual oil in industrial wastewater. Thermogravimetric and basic physical property analyses indicated a synergistic effect between drilling fluid solid waste and biomass materials, showing that joint pyrolysis of the two can enhance the yield of active materials. The adsorption performance of mixed-base active materials for heavy metal ions and residual oil were was tested. It was found that the removal rate of four heavy metal ions (Cr6+, Mn2+, Cu2+, and Zn2+) from the solution could reached 57.1 %, 96.3 %, 99.0 % and 94.1 %, respectively, at a concentration of 0.5 g/L of mixed-base active materials. Characterization revealed that the mixed-base activated carbon has a well-developed pore structure and numerous types of functional groups. The isothermal adsorption process of heavy metal ions by the active material is consistent with the Langmuir model and belongs to the monomolecular layer adsorption. The adsorption rate model of residual oil in wastewater by active materials conforms to the pseudo-second-order equation. The adsorption performance of mixed-base active materials primarily stems from physical adsorption enabled by their well-developed internal pore structure, along with chemical adsorption facilitated by oxygen- and nitrogen-containing functional groups on the surface.

Vapor-phase reduction synthesis of N, S co-doped graphene/MWCNT hybrid membrane for all-solid-state supercapacitors and adsorption of organic pollutants

Owing to the limited reserves of fossil fuels, many researchers are focused on seeking advanced materials to relieve the drawbacks caused by the imbalance between the supply and demand of fossil fuels. In this study, a N, S co-doped graphene/multi-walled carbon nanotubes hybrid membrane (GMHE) was synthesized by flow-directed assembly followed by vapor-phase reduction. The resulting hybrid membrane not only exhibited excellent capacitance performance, but also good adsorption capacity for organic pollutants owing to its high electrochemical activity, well-developed pore structure, and rich surface state. The assembled GMHE all-solid-state symmetric supercapacitor delivered a high power density of 6000 W·kg−1 at an energy density of 16.0 W·h·kg−1 and superior capacitance stability (retaining 97.2 % of its initial capacitance value at 3 A·g−1). The adsorption capacity of the GMHE for organic pollutants was 50 times (chlorobenzene) its own mass. In addition, the hybrid membrane exhibited remarkable reusability over in adsorption–combustion cycles. The judiciously designed bifunctional membrane material developed herein can be directly applied in energy storage and oil pollution cleanup, supporting sustainable economic development.

Sustainable protein/polysaccharide aerogel for the simultaneous and efficient removal of multiple organic contaminants: Insights from DFT calculations and phenomenological mass–transfer modeling

Wastewater contains various organic contaminants that pose great hazards to human health and the environment. A protein/polysaccharide-derived aerogel, namely, ICMA, was developed as a high-performance adsorbent for the simultaneous and efficient removal of diverse contaminants from wastewater, including melanoidin (MLE), Congo red (CR), and diclofenac (DIC). Metal organic framework (UiO-66-NH2), as a regulatory factor, significantly improved the porosity and pore volume of the ICMA to enhance the capture performance of contaminants. The ICMA exhibited outstanding adsorption efficiency owing to the incorporation of ample polyamine functional groups and its well-developed pore structure, large porosity and pore volume, and remarkable heat resistance. The equilibrium capture capacities of the ICMA were 1364, 2031, and 539 mg/g for MLE, CR, and DIC, respectively, with corresponding removal efficiencies all exceeding 90%. Furthermore, the ICMA can capture cationic dyes through MLE/CR/DIC-bridging interactions. After five cycles, the used ICMA can still maintain a high contaminant removal rate/amount, demonstrating good reusability. The classic adsorption model showed that the capture of contaminants by the ICMA is a double-layered and heterogeneous adsorption orientation. A brand new LWAMTM model demonstrated that the adsorption mass–transfer process is jointly determined by the external mass conveyance, pore diffusion, and adsorption on the active site. Multiple characterizations indicated that the contaminant adsorption onto the ICMA was mainly facilitated by charge interactions, with H-bonds playing a secondary role. Quantum chemical theory simulations further provide insights into the atomic-level mechanisms involved in the capture of contaminants. Hirshfeld surface analysis revealed that the ICMA functions as both an H-bond acceptor and a donor during contaminant adsorption. Scale-up and upgrade adsorption were performed to treat actual/simulated wastewater, establishing the groundwork for the industrial implementation of the ICMA.

Physicochemical Characteristics of Residual Carbon and Inorganic Minerals in Coal Gasification Fine Slag.

Investigating the physicochemical properties and embedding forms of residual carbon (RC) and slag particles (SPs) in coal gasification fine slag (FS) is the basis for achieving its separation and utilization. An in-depth understanding of their compositional characteristics allows for targeted treatment and utilization programs for different components. In this work, the physicochemical properties and embedding forms of RC and SPs in FS were systematically investigated. An innovative calculation method is proposed to determine the mass fraction of dispersed carbon particles, dispersed mineral-rich particles, and carbon-ash combined particles by using a high-temperature heating stage coupled with an optical microscope. The unburned RC with a rough, loose surface and a well-developed pore structure acted as a framework in which the smaller spherical SPs with a smooth surface were embedded. In addition, the sieving pretreatment process facilitated the enrichment of the RC. Moreover, the RC content showed significant dependencies according to the FS particle size. For FS with a particle size of 0.075-0.150 mm, the mass proportions of dispersed carbon, ash particles, and the carbon-ash combination were 15.19%, 38.72%, and 46.09%, respectively. These findings provide basic data and reliable technical support for the subsequent carbon and ash separation process and the comprehensive utilization of coal gasification slag.

Efficient selective adsorption of Cr(VI) by S-doped porous carbon prepared from industrial lignin: Waste increment and wastewater treatment

Industrial lignin is a waste product of the paper industry, which contains a large amount of oxygen group structure, and can be used to treat industrial wastewater containing Cr(VI). However, lignin has very low reactivity, so how to enhance its adsorption performance is a major challenge at present. In this study, a two-stage hydrothermal and activation strategy was used to activate the lignin activity and doping S element to prepare high-performance S-doped lignin-based polyporous carbon (S-LPC). The results show that the surface of S-LPC is rich in S and O groups and has a well-developed pore structure, which is very beneficial to Cr(VI) uptake -reduction and mass transfer on the material. In the wastewater, the utmost adsorption potential of Cr(VI) by S-LPC achieved 882.83 mg/g. After 7 cycles of regeneration, the adsorption of S-LPC decreased by only approximately 18 %. Ion competition experiments showed that S-LPC has excellent specificity for Cr(VI) adsorption. In factory wastewater, the adsorption performance of S-LPC for Cr(VI) remained above 95 %, which shows the excellent performance of S-LPC in practical applications. The results are of great significance for green chemical utilization of waste lignin, treatment of industrial wastewater and sustainable development.

Facile synthesis of inherently nitrogen-doped PAN-derived microporous carbons activated with NaNH2 for selective CO2 adsorption and separation

N-doped porous carbons (PCs) are extensively researched for CO2 capture and separation under flue gas conditions, but their complex and expensive preparation methods hinder widespread industrial use. Herein, we present a direct approach for synthesizing N-doped PCs by utilizing polyacrylonitrile (PAN) and NaNH2 as precursors, without the need for any solvents. The utilization of NaNH2 as both a porogen and nitrogen supply during carbonization is primarily responsible for the formation of the well-developed pore structure and high specific surface area of N-doped PCs. The optimized sample “PN-3” demonstrated excellent textural features with an excellent specific surface area (SSA) of 2490 m2/g, a pore volume of 2.0559 cm3/g, a well-defined pore size distribution (PSD), and abundant micropores (<1 nm). In addition, PN-3 has the highest pyrrolic nitrogen content (∼40.1 at.%), resulting in a significant capacity for CO2 adsorption (7.15 mmol/g at 273 K/1bar, 4.56 mmol/g at 298 K/1 bar, 26.2 mmol/g at 298 K/ 40 bar). Furthermore, it exhibits an outstanding CO2/N2 selectivity (∼102) based on the ideal adsorbed solution theory (IAST) at 273 K, surpassing the performance of most of previously reported biomass and polymer-derived N-doped carbons in terms of CO2 adsorption and separation. In addition, the adsorption process is characterized by a modest heat of adsorption (39.10 kJ/mol) and a steady cyclic pattern of CO2 adsorption–desorption under flue gas settings (15 % CO2 and 85 % N2). This indicates that the adsorption is mostly governed by physisorption, which allows for an energy-efficient regeneration process. In summary, this study showcases the successful production of highly PCs that can effectively adsorb CO2, enlightening the way toward establishment of a cost-effective and facile synthetic protocol for achieving CO2 capture/separation at the commercial scale.

Cerium-based sorbent with 100% Ce(III) and high dispersion for enhanced phosphate removal from wastewater

Under the double pressure of eutrophication and phosphorus deficiency, there is an urgent need to remove excess phosphate from wastewater efficiently. Preparing cerium-based materials with excellent application potential inevitably leads to Ce(III) oxidation to Ce(IV), which reduces the phosphate adsorption effect and restricts its development. To solve this problem, we introduced a protective agent and successfully synthesised cerium-modified activated carbon sorbent containing 100 % Ce(III) during the synthesis process. Compared with CeAC without a protecting agent, CeAC-A contained more Ce(III) (100 %) and exchange groups (–OH accounted for 82.76 %), achieving an adsorption capacity of up to 448.57 mg-P/g Ce, improving of 4.3 times. At the same time, the size of the cerium active component was reduced from the micron level to the nanometer level, and the mass transfer rate was significantly improved. In addition, with the enormous specific surface area and well-developed pore structure of activated carbon, it showed high dispersibility, with P/Ce molar ratio as high as 2.03, which is 1.1–4.8 times higher than other cerium-based adsorbents. Phosphate was removed primarily through electrostatic attraction and ligand exchange. In treating municipal wastewater with complex water quality, CeAC-A showed strong selectivity, a wide range of adaptability and easy repeat regeneration, making it a promising adsorbent for phosphate uptake from wastewater.

The synthesis of multi-level porous MOF composite materials with different MOF contents

To address the inherent limitations of current MOF synthesis, where pore size is restricted to micropores or small mesopores, we successfully synthesized MOF composite materials with well-developed porous structures using a self-template approach. These pores encompass not only the intrinsic micropores or small mesopores of MOFs but also the template-induced large pores. During the experimental process, we achieved the synthesis of composite materials with varying MOF contents by modifying experimental conditions. Through this design, we not only achieved selective adsorption of guest molecules but also significantly increased the porosity, thereby enhancing the mass transfer efficiency of guest molecules and the utilization rate of materials. This research breakthrough offers new insights and solutions for addressing critical issues in fields such as gas separation, energy storage, and catalysis.

Oxygen-vacancies-rich TinO2n-1 quantum dots embedded Ti3CNTx/CNTs foam by HCl induced self-assembly and spontaneous oxidation towards strong and multiband microwave absorption

Ti3CNTx/TinO2n-1 foam and Ti3CNTx/CNTs/TinO2n-1 foam were prepared by hydrochloric acid (HCl) induced self-assembly and freeze-drying, during which oxygen-vacancies-rich TinO2n-1 quantum dots in situ grown on Ti3CNTx nanoflakes as a result of their slight and spontaneous oxidation. The well-developed pore structure, abundant interfaces, unique dangling bonds, defects and terminated groups on highly conductive Ti3CNTx nanoflakes, as well as the oxygen vacancies in TinO2n-1 quantum dots render the foams with superior impedance matching, intensive multiple reflection and dielectric loss. By immersing the foams into molten paraffin (absorber content: 4.2 wt%), excellent microwave absorption (MA) properties were achieved: an effective absorption bandwidth (EAB) of 5.2 GHz (1.55 mm) and a reflection loss (RL) of −81.3 dB (1.85 mm) for Ti3CNTx/TinO2n-1foam, and an EAB of 6.4 GHz and a RL of −54.3 dB (1.85 mm) for Ti3CNTx/CNTs/TinO2n-1 foam (15 wt% CNTs). Moderate addition of CNTs enhanced the conduction loss and polarization loss, leading to a larger EAB. When adjusting the thickness (1.2–5 mm), the EAB of Ti3CNTx/TinO2n-1 foam (14.7 GHz) and Ti3CNTx/CNTs/TinO2n-1 foam (15.3 GHz) both covered the C, X and Ku band. This work offers a simple and facile method for constructing Ti3CNTx-based foams as excellent MA materials.

Effect of Surface Area, Particle Size and Acid Washing on the Quality of Activated Carbon Derived from Lower Rank Coal by KOH Activation

The use of coal-derived activated carbon (AC) for water treatment applications demands more sustainable production methods, with chemical activation emerging as a promising alternative to thermal activation due to its higher AC quality, lower carbon burn-off, and higher yield. The study explored the effect of surface area, particle size and acid washing on the quality of AC derived from three seams of lower-rank Collie coal under the same activation conditions with potassium hydroxide (KOH). The quality of AC was determined by surface area and iodine number. The study demonstrates that Collie coal, suitable for AC production via KOH activation, yielded iodine numbers of 640 and 900 mg/g, with yields of 53 and 57 wt.%. Particle size influenced AC yield, with finer particle sizes yielding AC at 57–59 wt.%, whereas coarser ones yielded around 58–65 wt.%. SEM analysis shows the well-developed porous structure in Collie coal-derived activated carbons, with cleaner particles after acid washing. A positive correlation exists between coal surface area and AC iodine numbers, with higher values in coal samples correlating to increased iodine numbers in resulting AC. The regression model’s predicted values yield a coefficient of determination (R²) of 0.99.

Removal of malachite green by in-situ N-doped biochar derived from wheat bran: kinetics, isotherms, and adsorption mechanism study

The biomass-based adsorbents offer a promising solution for wastewater decolorization owing to their superior specific surface area, low-budget, high adsorption capacities, and environmental sustainability. In this work, wheat bran (WB) was used as raw material for the production of in situ N-doped biochar through a molten salt template method, and the adsorption characteristics of Malachite Green (MG) onto biochars prepared from WB by immersing and non-immersing (BC–NaK and BC–NaK-n) in the mixed salt solution (NaCl and KCl) were investigated. The experimental results indicated that the adsorption capacity of MG onto the BC–NaK was significantly better than BC–NaK-n, which was attributed to the rich functional groups and well-developed pore structure of BC–NaK. The adsorption equilibrium data of MG onto the BC–NaK was fitted well to Sips and Koble-Corrigan isotherm models and adsorption process of MG was spontaneous and endothermic. Meanwhile, the pseudo-second-order model was successfully applied to depict the adsorption process of MG. Furthermore, the adsorption of MG onto BC–NaK was primarily regulated by H-bonding, π–π interaction, hydrophobic interaction, electrostatic interaction. The maximum saturated adsorption capacity of the BC–NaK was 880.14 ± 9.35 mg g−1 at 298 K, further demonstrating that biochar prepared from wheat bran provided a long-term development strategy for dye wastewater treatment.