BET Specific Surface Area Research Articles

Adsorption of tetracycline from aqueous solution by ZIF-8: Isotherms, kinetics and thermodynamics

In this study, ZIF-8 nanoparticles were synthesized using a simple method at room temperature. The ZIF-8 nanoparticles were then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (Brunauer-Emmett-Teller) specific surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and zeta potential. Subsequent batch adsorption experiments evaluated the adsorption performance of ZIF-8 on tetracycline, examining key pa-rameters like reaction time, pH, temperature, and adsorbent dosage. The results revealed a removal rate for TC of up to 90.59%. The adsorption data aligned with the Sips model, showcasing a maximum adsorption capacity of 359.61 mg/g at 303K. Further, the adsorption kinetics adhered to the pseudo-second-order kinetic model with an equilibrium adsorption capacity of 90 mg/g at 303K. The considerable specific surface area of ZIF-8, standing at 1674.169 m2/g, likely enhances the adsorption efficacy. Analysis using XRD and FTIR confirmed the adsorption of TC on the ma-terial's surface. Overall, the predominant driving forces behind the adsorption process were identified as electrostatic interactions and π-π stacking interactions.

Enhanced dechlorination of 2,4-dichlorophenol using nanorod palygorskite-loaded Fe/Ni nanoparticles: Performance evaluation, influencing factors and action mechanism of Fe and Ni

The basic structural unit of palygorskite (P) consists of rod-shaped crystals with a diameter ranging from 20 to 70 nm. However, due to strong hydrogen bonding and electrostatic forces, most palygorskite rod crystals tend to aggregate, limiting its nanomaterial properties in practical application. To address this limitation, the study focused on dissociating palygorskite aggregates and incorporating them into nanorod palygorskite-loaded Fe/Ni bimetallic nanoparticles (nP-nFe/Ni) synthesis. This approach facilitated the dissociation of palygorskite aggregates and enabled the dispersion of Fe/Ni nanoparticles by palygorskite nanorods. The results revealed that the BET specific surface area of nP-nFe/Ni was significantly higher at 86.17 m2/g compared to 33.62 m2/g for nFe/Ni. Consequently, the dechlorination efficiency of nP-nFe/Ni for 2,4-dichlorophenol (2,4-DCP) at 120 min was 22.4% higher than that of nFe/Ni, despite nP-nFe/Ni containing only 35.1% of the Fe content found in nFe/Ni at the same dosage. Moreover, it was observed that acidic conditions favor maximum dichlorination, while higher temperatures enhance the dechlorination rate. The action mechanism of Fe was identified as the generation of H2, which is catalyzed by Ni to form active hydrogen (H*) that attack the C-Cl bonds of 2,4-DCP for hydrodechlorination. Ni played a vital role in catalyzing H2 conversion to H* , accelerating H2 production by Fe, and inhibiting Fe passivation. These findings are crucial for the application of nano iron technology and nano-scale palygorskite in water and wastewater treatment.

Composite of titanium dioxide and hydrogen-bonded organic framework − A dye-sensitized photocatalyst

To improve the utilization of TiO2 with low visible light absorption behavior, a 2D hydrogen-bonded organic framework (HOF), HOF-TCPB-373, was employed and integrated with TiO2 to create a composite catalyst (TiO2@HOF). 40 %TiO2@HOF exhibits a larger BET specific surface area (26.68 m2/g) and a more negative Zeta potential (–23.78 mV) compared to HOF-TCPB-373. Compared to TiO2, 40 %TiO2@HOF is more hydrophilic with the water contact angles of 51°. A dye-sensitized catalytic system based on 40 %TiO2@HOF was established. 40 %TiO2@HOF exhibits the highest RhB removal efficiency reaching 99 %, combining photodegradation (69 %) and adsorption (30 %). The 40 %TiO2@HOF composite shows both superior adsorption and photodegradation capacities for RhB compared to pristine TiO2 and HOF-TCPB-373, attributing to the synergistic effect and heterojunction structure formed between the two components. The mechanism of dye sensitization and photocatalytic degradation was explained by energy band analysis and active species capture experiments. The degradation was driven by RhB-excited and charge transfer on 40 %TiO2@HOF.

Recovery of Chlorosilane Residual Liquid to Prepare Nano-Silica via the Reverse Micro-Emulsion Process.

In this paper, nano-silica particles were prepared from chlorosilane residue liquid using an inverse micro-emulsions system formed from octylphenyl polyoxyethylene ether (TX-100)/n-hexanol/cyclohexane/ammonia. The influence of different reaction conditions on the morphology, particle size, and dispersion of nano-silica particles was investigated via single-factor analysis. When the concentration of chlorosilane residue liquid (0.08 mol/L), hydrophile-lipophilic-balance (HLB) values (10.50), and the concentration of ammonia (0.58 mol/L) were under suitable conditions, the nano-silica particles had a more uniform morphology, smaller particle size, and better dispersion, while the size of the nano-silica particles gradually increased with the increase in the molar ratio of water to surfactant (ω). The prepared nano-silica was characterized through XRD, FT-IR, N2 adsorption/desorption experiments, and TG-DSC analysis. The results showed that the prepared nano-silica was amorphous mesoporous silica, and that the BET specific surface area was 850.5 m2/g. It also had good thermal stability. When the temperature exceeded 1140 °C, the nano-silica underwent a phase transition from an amorphous form to crystalline. This method not only promoted the sustainable development of the polysilicon industry, it also provided new ideas for the protection of the ecological environment, the preparation of environmental functional materials, and the recycling of resources and energy.

Facile Preparation of a Novel HfC Aerogel with Low Thermal Conductivity and Excellent Mechanical Properties.

Aerogels emerge as captivating contenders within the realm of high-temperature thermal resistance and thermal insulation. Nevertheless, their practical applications are usually constrained by their inherent brittleness when subjected to rigorous conditions. Herein, employing hafnium dichloride oxide octahydrate (HfOCl2·8H2O) as the hafnium source and resorcinol-formaldehyde (RF) as the carbon precursor, hafnium carbide (HfC) aerogels are fabricated via the sol-gel method complemented with carbothermal reduction reaction. Investigations are conducted into the effects of various molar ratios, duration, and temperatures of calcination on the microstructural features and physico-chemical characteristics of the as-prepared HfC aerogel. The aerogel shows a high BET-specific surface area (601.02 m2/g), which is much larger than those of previously reported aerogels. Furthermore, the HfC aerogel exhibits a low thermal conductivity of 0.053 W/(m·K) and a compressive strength of up to 6.12 MPa after carbothermal reduction at 1500 °C. These excellent thermal insulation and mechanical properties ensure it is ideal for the utilization of high-temperature thermal resistance and thermal insulation in the fields of aerospace.

Pore-fracture and permeability heterogeneity of different marcolithotypes of medium-rank coals in Jixi Basin, China

The pore-fracture system of different marcolithotypes (bright, semi-bright, semi-dull and dull coals) is quite different, which has great influences on coalbed methane (CBM) exploitation. Here the optical microscope (OM), scanning electron microscope (SEM), mercury intrusion porosimetry (MIP), low-temperature nitrogen adsorption (LTND) and X-ray computed tomography (X-CT) are performed on different marcolithotype coals from Jixi Basin. From bright coals to dull coals, “ink bottle” shaped pores account for a gradually increasing proportion of the transition pores, but contribute fewer mesopores. The results of LTND and MIP indicate that bright coals have the poorest mercury removal efficiency and lowest BET specific surface area, while the opposite appears to be the case for dull coals. According to the pore size distribution based on LTND and MIP, from bright coal, semi-bright coal, semi-dull coal to dull coal, the total pore volume gradually decreases, with the proportion of macropore volume occupying 76.2%, 5.1%, 3.7% and 1.7%, respectively. On the basis of the 3D reconstruction of the pore-fracture system obtained from X-CT, the bright coal is characterized by high connected porosity and total porosity, presenting the best pore-fracture system. The pore network of bright coal is three-way interconnected with the largest number of pores and the shortest and densest throats, which facilitates the communication of fluids between the pores. In contrast, dull coals with a unidirectionally connected pore network model, fewer pores and sparse throats, have a poor seepage capacity. In addition, the X-CT seepage simulation results and the gas permeability results confirm the superiority of the pore-fracture system in bright coals.

Structural Modulation of Nitrogen-Rich Covalent Organic Frameworks for Iodine Capture.

Developing efficient adsorbent materials for iodine scavenging is essential to mitigate the threat of radioactive iodine causing adverse effects on human health and the environment. In this context, we explored N-rich two-dimensional covalent organic frameworks (COFs) with diverse functionalities for iodine capture. The pyridyl-hydroxyl-functionalized triazine-based novel 5,5',5″-(1,3,5-triazine-2,4,6-triyl)tris(pyridine-2-amine) (TTPA)-COF possesses high crystallinity (crystalline domain size: 24.4 ± 0.6 nm) and high porosity (specific BET surface area: 1000 ± 90 m2 g-1). TTPA-COF exhibits superior vapor-phase iodine adsorption (4.43 ± 0.01 g g-1) compared to analogous COF devoid of pyridinic moieties, 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT)-COF. The high iodine capture by TTPA-COF is due to the enhanced binding affinity conferred by the extra pyridinic active sites. Furthermore, the crucial role of long-range order in porous adsorbents has been experimentally evidenced by comparing the performance of iodine vapor capture of TTPA-COF with an amorphous network polymer having identical functionalities. We have also demonstrated the high iodine scavenging ability of TTPA-COF from the organic and aqueous phases. The mechanism of iodine adsorption by the heteroatom-rich framework is elucidated through FTIR, XPS, and Raman spectral analyses. The present study highlights the need for structural tweaking of the building blocks toward the rational construction of advanced functional porous materials for a task-specific application.

Investigation on coal floatability and pore characteristics using acidification method

This paper investigated the relationship between coal floatability and pore characteristics from the perspective of froth flotation. Three types of coal samples with different ash contents were pretreated with HCl and acetic acid solutions to alter the pore features. The X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) measurements were conducted to specify the reactions that happened in acidification. The batch flotation and contact angle measurements were conducted to evaluate the floatability of the coal samples. The liquid nitrogen adsorption and mercury intrusion porosimetry (MIP) measurements were applied to measure the pore characteristics of the coal. The acidification treatment partially dissolved mineral components and organic functional groups on the coal surface but did not change the types of the major functional groups. The sedimentation of liberated fine minerals on coal pores caused the decrease in pore volume. The BET specific surface area of the three coal samples after acidification was found to have consistent negative relations with the flotation recovery and combustible recovery rate. This indicated the adverse impact of porosity in coal flotation. The floatability of coal is mainly influenced by the pores at the size fraction of 1–20 μm by pore volume. The nano-scale size pore and fine mineral inside the micron pore increased the water-wettability and resulted in the low floatability of coal.

Graphite-assisted microwave carbon dioxide gasification of wet stalks

In order to realize the low-carbon gasification of the typical wet stalks, the graphite was used as the microwave-absorbing agent and the heat transfer medium in the microwave field, and CO2 was used as the gasification agent to explore the characteristics of microwave CO2 gasification. After mixing the corn stalks, the rice stalks or the wheat stalks with different water contents and the graphite in a mass ratio of 4:1, CO2 was introduced for gasification in a microwave field. Experiments showed that with the increase in the water content, the carbon conversions, the gas yields and the volume fractions of the effective components all increased slowly in the front and rear sections, and increased rapidly in the middle section. When the CO2 flow rate was 0.6 Nm3·kg−1·min−1, the carbon conversions, the gas yields and the volume fractions of the effective components all reached their peaks. It was found that the structure of the three stalks changed from smooth to porous during the intermediate process of the graphite-assisted microwave gasification. The deashed stalks with water content of 60 % was gasified in a microwave field of 700 W for 1.25 min, and the BET specific surface areas of the generated porous carbon reached 2041–2054 m2 g−1, and the volume fractions of the effective components of the gasification gas were more than 95 %. With the prolongation of the gasification time, the carbon conversions increased slowly in the early and late stages, but increased rapidly in the middle stage. The reason was that the large amount of porous carbon generated in the middle stage was the gasifiable strong microwave-absorbing agent, which greatly increased the gasification temperature and accelerated the reaction rates. When the graphite was reused 10 times, the carbon conversions could still reach more than 80 %. The XRD tests were carried out on the graphite used many times to explore its deactivation mechanism. This paper has practical significance for the low-carbon CO2 recycling of stalks biomass, and provides a new way for the preparation of biomass-based porous carbon.

Improving enzyme accessibility in the aqueous enzymatic extraction process by microwave-induced porous cell walls to increase oil body and protein yields

Aqueous enzymatic extraction (AEE) is a green and sustainable extraction method. However, the intact cell wall hinders the accessibility of enzymes, severely limiting the efficiency and application of the AEE method. In this study, microwave-assisted aqueous enzymatic extraction (MAAEE) was used to degrade the peanut cell wall and improve the yield of oil and protein. Transmission electron microscopy, scanning electron microscopy, BET-specific surface area, Fourier transform infrared spectroscopy, X-ray diffraction, and chemical composition analysis were used to characterize the structure and chemical changes of the peanut cell wall. The results showed that microwave treatment could break the structure of the peanut cell wall, increase the porosity of raw materials, accelerate the efficiency of enzymatic hydrolysis, and promote the extraction of oil and protein. Compared with raw peanut powder (MC-0), microwaved peanut powder (MC-4) had a higher oil body yield (>44%) and protein release rate (>76%). At the microscopic level, cell wall rupture, oil accumulation, and cell contents scattered outside the cell were observed. The mean pore size, pore volume, and specific surface area increased by 54.1%, 149.4%, and 63.5%, respectively, while the crystallinity decreased by 4.4%. The content of hemicellulose and CDTA-soluble pectin (CSP) decreased by 18.6% and 32.9%, respectively. The degradation rates of cellulase and pectinase on cell wall components were significantly increased by 8.5%–43.2% (p < 0.05). In summary, microwave-induced porous cell walls could significantly improve enzyme accessibility, accelerate enzymatic hydrolysis efficiency, and promote oil and protein extraction.

Zn-based Metal-Organic Frameworks Using Triptycene Hexacarboxylate Ligands: Synthesis, Structure, and Gas-Sorption Properties.

A series of metal-organic frameworks (MOFs) based on zinc ions and two triptycene ligands of different size were synthesized under solvothermal conditions. The structural analyses revealed that these are isostructural three-dimensional-network MOFs. The high porosity and thermal stability of these MOFs can be attributed to the highly rigid triptycene-based ligands. Their BET specific surface areas depend on the size of the triptycene ligands. In contrast to these surface-area data, the H2 and CO2 adsorption of these MOFs is larger for MOFs with small pores. Consequently, we introduced functional groups to the bridge-head position of the triptycene ligands and investigated their effect on the gas-sorption properties. The corresponding results unveiled the role of the functional groups in the specific CO2 binding via an induced interaction between adsorbates and the functional groups. Excellent H2 and CO-2 properties in these MOFs were achieved in the absence of open metal sites.

Antimicrobial activity of biogenic-synthesized novel bimetallic nanospinel LiCu-ferrite particles: Experimental and computational studies

An aqueous carob leaf extract was employed in the current study as a biogenic agent (reducing and capping agents) for the synthesis of novel bimetallic lithium and copper-based nanospinel ferrites (LiCu-F) with antibacterial activity. LiCu-F has a considerable number of surface -OH groups, a BET-specific surface area of 72.5 m2/g, a mean particle size of 59.8 nm, and a crystallinity index of 78.9%, according to the results of the physicochemical characterisation of the ferrite. Within the first 60 min, LiCu-F showed bacteriostatic and bactericidal effects on S. aureus and E. coli based on the time-kill assay. 0.4 mg of LiCu-F demonstrated 67.9% bacteriostatic effects on E. coli while exhibiting 100% inactivation of S. aureus strains, demonstrating that the gram-positive bacteria are more susceptible to LiCu-F. The computational molecular docking analysis demonstrated that LiCu-F has a higher binding affinity for S. aureus (-38.89 kcal/mol) than E. coli (-29.16 kcal/mol), which is consistent with the experimental findings. With an LD50 of 1000 mg per kg of body weight based on a computational prediction tool, LiCu-F is cytotoxic to bacteria and can cause DNA damage and cell death in bacterial strains.

Synthesis and application of Pt-containing catalysts based on mordenite zeolite and natural halloysite nanotubes in the gas-phase isomerization of C-8 aromatic fraction

The MOR-type zeolite was synthesized by a template-free method using natural aluminosilicate halloysite nanotubes (HNT) as a hard template and a source of aluminum and silicon. Samples were studied using a complex of physicochemical methods of analysis: XRD, TEM, N2 physisorption, NH3-TPD and XRF. Specific BET surface area of MOR prepared using HNT is 306 m2/g, mesopores in the MOR:HNT accounted for 30 % of the total pore volume. Based on the synthesized materials (MOR, MOR:HNT and MOR + HNT), Pt-containing catalysts were prepared. The catalysts were investigated in the gas-phase isomerization of C-8 aromatic fraction in a temperature range of 360–420 °C, varying LHSV from 2 to 6 h−1, at H2 pressure of 1 MPa and hydrogen/feedstock volume ratio of 900 nl/l. The prepared catalysts demonstrated strong activity in ethylbenzene transformation (more than 95 %), while providing a high yield of p-xylene (more than 95 % of thermodynamic value).

High-affinity fluoride ions absorbent from TiO2-based ionic liquid pyridinium propylsulfonate

The development of materials for high efficiency removal of fluoride ions (F-) from sewage water remains a significant challenge. Unfortunately, traditional metal oxide adsorbents remove F-, but suffer from poor adsorption capacity and generate secondary pollution due to byproducts. To solve this problem, a highly-efficient and recyclable F- adsorbent with rich pore structure (BET specific surface area of 172.15 m2·g−1) was developed by multi-element doping strategy. The F- adsorbent was composed of TiO2 as substrate and ionic liquid pyridinium propylsulfonate as doping. This absorbent displayed good F- adsorption capacity (qmax = 224.11 mg∙g−1, 298 K), which operated through single molecule complex adsorption mechanism, outperformed many commercial adsorbents, and it also exhibited satisfactory adsorption kinetics for improving the efficiency of water treatment. Interestingly, the porous adsorbent had excellent regeneration potential (maintaining more than 70 % F- removal efficiency after 5 cycles of adsorption and desorption) and practical ability in complex water environments of tap water, lake and river. More importantly, a fixed-bed for F- adsorption was designed to simulate the equipment of sewage treatment plant. The breakthrough time and saturation time obtained by fixed-bed experiments proved the practical application value of this novel adsorbent. Most strikingly, the cost estimate showed that the economic feasibility and practical promotion potential of the renewable, continuous and efficient F- wastewater purification system using the novel absorbent were remarkable. This innovative approach showcases a viable solution for addressing F- removal and water treatment.

Influence of heat treatment on the microstructure and surface groups of Stöber silica

Heat treatment is routinely utilized in preparing nanoporous materials (including Stöber silica), and can substantially affect their performance in diverse application fields. However, the effects of heat treatment at different temperatures on the structure and surface properties of Stöber silica have not been systematically investigated before. In this work, Stöber silica (washed with water or ethanol) was calcined at different temperatures (from 250 °C to 1000 °C), and the heat-treated samples were characterized through nitrogen adsorption at 77 K, scanning electron microscopy, simultaneous thermal analysis, elemental analysis, and Fourier-transform infrared spectroscopy. The results show that there is no significant difference in the morphology and particle size of the calcined samples. The internal micropores almost collapse after calcination at 500 °C, and the pores with a smaller diameter are the first to shrink during calcination. The variation in the number of the surface hydroxyl groups and ethoxyl groups with the calcination temperature is discussed in detail. The carbon content analysis and differential scanning calorimetry curves reveal that the surface ethoxyl groups (for the samples washed with ethanol) are completely removed after calcination at 500 °C. After calcination at temperatures above 800 °C, the hydroxyl groups almost completely condense into siloxanes. The specific surface area calculated according to the thermogravimetric mass loss and surface hydroxyl density is found to be significantly different from the measured Brunauer–Emmett–Teller specific surface area. Our results may offer practical guidance for the application of Stöber silica subjected to similar heat-treatment processes.

Rice husk-derived sodium hydroxide activated hierarchical porous biochar as an efficient electrode material for supercapacitors

In this study, one-step pyrolysis technique and NaOH chemical activation method were used to synthesize hierarchical porous biochar from rice husk. The existence of carbonaceous structure in biochar samples was confirmed by X-ray diffraction, field-emission scanning electron microscopy, elemental mapping, Raman spectroscopy, Brunauer-Emmett-Teller surface area, and X-ray photoelectron spectroscopy analysis. Activation of NaOH in rice husk biochar (ARB) sample suggested seven-fold enhancement of BET specific surface area (307.42 m2 g−1) as compared to rice husk biochar (RB). The NaOH activation also provides the enhancement of specific capacitance in RB. The boosting of supercapacitors (SCs) performance of ARB was proved by a larger loop in cyclic voltammetry and triangular shape along with a longer discharge time in galvanostatic charge-discharge curves as compared to RB. The electrode revealed excellent cyclic stability up to 4000 cycles with 94% retention. Furthermore, electrochemical impedance spectroscopy and galvanostatic charge-discharge curves showed evidence of electrode stability. The mechanisms related NaOH activation and enhancement of supercapacitor performance were well explained. These results suggest that NaOH treated RB could be promising low-cost electrode material for SCs application.

Performance of a rotating packed bed with blade packings in synthesizing nano-sized Fe3O4 particles

Nano-sized Fe3O4 particles were continuously synthesized in the rotating packed bed with blade packings where the rotational speed was set at 1800 rpm, the liquid flow rate of aqueous FeCl2/FeCl3 was kept at 0.5 L/min, and the liquid flow rate of aqueous NaOH was maintained at 0.5 L/min with the chemical co-precipitation route that the synthesis temperature was fixed at 25 °C, the FeCl2 concentration was fixed at 0.15 mol/L, the FeCl3 concentration was fixed at 0.3 mol/L, and the NaOH concentration was fixed at 1.2 mol/L. The average crystallite size and mean particle size of the as-synthesized nano-sized Fe3O4 particles were 12.7 nm and 10.9 nm, respectively. The rate of continuous synthesis of nano-sized Fe3O4 particles was 23.6 kg/day. The as-synthesized nano-sized Fe3O4 particles exhibited a superparamagnetic characteristic at 25 °C. Furthermore, the saturation magnetization of the as-synthesized nano-sized Fe3O4 particles was 66.4 emu/g. The as-synthesized nano-sized Fe3O4 particles had the Type-IV isotherm for N2 adsorption-desorption with a BET specific surface area of 109.4 m2/g. The maximum Orange G adsorption capacity of the as-synthesized nano-sized Fe3O4 particles at 25 °C and pH 3 was 55.0 mg/g. This maximum Orange G adsorption capacity was much higher than that (5.7 mg/g) of the commercial nano-sized Fe3O4 particles that were purchased from Sigma-Aldrich (SA-Fe3O4) because the as-synthesized nano-sized Fe3O4 particles had a smaller mean particle size than SA-Fe3O4. Accordingly, the as-synthesized nano-sized Fe3O4 particles are a promising magnetic adsorbent in the removal of Orange G from water.

Depth dependence of hardness and reaction in metakaolin‐based geopolymers cured at low humidity

AbstractCompared to metakaolin‐based sodium and potassium geopolymers cured at 20°C/100% relative humidity, geopolymers, which were cured at 20°C/40% relative humidity, were found to have considerable changes in the nanoscale structure and physical properties near the surface due to dehydration that occurred before completely hardening. For low‐humidity samples, the density in a thin near‐surface region was higher than the bulk, while porosity and BET specific surface area were greatly diminished. The microhardness at the exposed surface was low but increased sharply within a small depth before decreasing with depth to a constant value, which depended on the initial water content and charge‐balancing cation. 29Si NMR spectroscopy showed that the extent of reaction also varied with distance from the exposed surface. Both the elevated microhardness and incomplete reaction were detected at distances of up to 1.5 cm from the exposed surface, indicating that premature dehydration can cause microstructural changes over length scales that may be significant in large, ambiently cured 3D‐printed geopolymers. These effects are reduced by the use of sodium rather than potassium as the charge‐balancing cation and by raising the initial water content of the geopolymer, although higher water content caused greater surface deformation during drying.

Preparation of amino-bagasse/metakaolin based geopolymer hybrid microsphere as a low-cost and effective adsorbent for Cu(Ⅱ)

This study focuses on the utilization of an amino-sugarcane bagasse/metakaolin-based geopolymer hybrid microsphere adsorbent (ASB-MGM) for the efficient removal of Cu2+ from aqueous solutions. The influence factors of pH value and adsorbent dosage on the adsorption amount of ASB-MGM were investigated. The BET specific surface area of the microsphere adsorbents enlarged from 18.09 m2/g to 49.16 m2/g with the incorporation of ASB, while reducing the average pore size from 17.59 nm to 7.76 nm. Characterization techniques including FT-IR, XPS, and SEM-EDS confirmed the successful doping of amino groups, enhancing the adsorption efficiency. The adsorption kinetics fitted a pseudo-second-order model with a maximum monolayer adsorption of 248.13 mg/g for Langmuir. Thermodynamic studies revealed that the adsorption process is a spontaneous heat absorption reaction with an increase in system disorder. The ASB-MGM-Cu was effectively regenerated using HCl (with concentration of 0.1 mol/L) and retained good adsorption capacity. The low-cost, eco-friendly synthesis method presented in this study offers a highly efficient approach for industrial-scale removal of Cu2+. Data avail abilityData will be made available on request.

Effect of Solid Electrolyte Interphase on Sodium-Ion Insertion and Deinsertion in Non-Graphitizable Carbon

Non-graphitizable carbon allows reversible sodium-ion intercalation and hence enables stable and high-capacity sodium storage, making it a promising material for achieving long-term cycling stability in sodium-ion batteries (SIBs). This study investigated the interfacial reactions between various electrolytes and a non-graphitizable carbon electrode for their use in SIBs. The morphology and particle diameter of the non-graphitizable carbon, HC-2000, remained unchanged after heat treatment, indicating its stability. The X-ray diffraction pattern and Raman spectrum suggested a disordered structure of HC-2000 carbon. The interlayer spacing, Brunauer–Emmett–Teller specific surface area, and density were determined to be 0.37 nm, 5.8 m2 g−1, and 1.36 g cm−3, respectively. Electrochemical impedance spectroscopy analysis showed that the charge transfer resistances differed between the Na salts and other electrolytes. Therefore, the use of a large amount of NaF in the solid electrolyte interphase (SEI) resulted in high charge transfer resistances at the non-graphitizable electrodes. However, there were no apparent differences in the activation energy or reversible capacity. In summary, NaF obstructs the penetration pathway of sodium ions into non-graphitizable carbon, impacting the charge transfer resistance and rate stability of SIBs. Charge–discharge measurements revealed reversible capacities of 260–290 mAh g−1, and the rate performance varied depending on the electrolyte. Therefore, an SEI containing minimal inorganic species, such as NaF, is desirable for efficient sodium-ion insertion into non-graphitizable carbon.