Specific Pore Research Articles

Exploring the Relationship Between Biochar Pore Structure and Microbial Community Composition in Promoting Tobacco Growth.

The potential benefits of biochar, a carbon-rich substance derived from biomass, for enhancing agricultural yield and soil health have drawn increasing interest. Nevertheless, owing to the lack of specialized studies, the role of its poly-spatial structure in the success of fostering plant growth remains unclear. This study aimed to assess the effects of various biochar pore shapes on tobacco growth and the underlying microbiological processes. Three pyrolysis temperatures (250 °C, 400 °C, and 550 °C) were used to produce biochar from tobacco stems, resulting in different pore structures (T3 > T2 > T1). We then used BET-specific surface area (BET), t.Plot micropore specific surface area (t.Plot), mesopore specific surface area (MSSA), specific pore volume (SPV), average pore size (AP), and mesopore pore volume (MPV) measurements to evaluate the effects of these biochars on tobacco growth and biomass accumulation, and microbial analyses were performed to investigate the underlying mechanisms. When applied to plants, biochar increased their growth compared to untreated controls. The most notable improvement in tobacco growth was observed in the biochar produced at 400 °C (T3), which possessed the largest and most advantageous pore structure among all treatments. Further studies demonstrated that biochars with greater specific surface areas (BET, t.Plot, and MSSA) positively altered the abundance of key microbial taxa (e.g., Stenotrophobacter, Ensifer, Claroideoglomus) and community composition, thereby encouraging plant development and biomass accumulation. Conversely, greater pore volumes (SPV, AP, and MPV) inhibited microbial activity and significantly affected growth and biomass accumulation. Structural equation modeling further demonstrated that the pore structure of biochar greatly affected plant growth by changing the relative abundance and community composition of soil microbes. Maximizing the benefits of biochar in stimulating plant growth and improving soil microbial communities depends on optimizing the material's pore structure, particularly by increasing the specific surface area. These findings will help expand the use of biochar in sustainable agriculture.

Synthesis of heterogeneous nanocomposite catalyst ZrO2@SBA-15 for formic acid production from hemicelluloses

Heterogeneous nanocomposite ZrO2@SBA-15 catalysts containing 10 wt. % of zirconium oxide were synthesized by two methods: co-condensation and incipient wetness impregnation. The silica support and catalysts were characterized by X-ray diffraction, gas adsorption, FTIR-spectroscopy and other physicochemical methods. As a result of zirconia introduction into the silica wall, the mesostructured of SBA-15 is preserved, but the specific surface area and pore Volume are reduced. It was established that during one-stage co-condensation synthesis, the particle fibers shorten and stick together. The catalysts were tested in the process of catalytic hydrolysis-oxidation of hemicelluloses of aspen wood. The optimal formic acid synthesis conditions were determined: 150°С, 3 h. The highest formic acid yield obtained over the catalyst obtained by co-condensation under best reaction conditions was 28.4 wt. %.

Investigation on preparation and properties of gel type 188W/188Re generator

As one of the most important integrated nuclides for diagnosis and treatment in recent years, rhenium-188 (188Re) has a broad scope in the clinical application. Due to the specific properties of such radionuclide, it was mainly provided by the chromatographic 188W-188Re generators. There is no doubt that the application of 188Re in the treatment of various diseases depended on the development of 188W-188Re generator. Considering the high standards of such technology on radioactive activity of 188W and impurity content, a 188W-188Re generator filled with the zirconium tungstate gel has been prepared in this work. The effects of molar ratio of chemical agents, pH, reaction temperature, drying methods, rinsing methods and other conditions on the synthesis of gel particles have been studied. Furthermore, a variety of characterization techniques were used to observe the macro-/micro-morphology and chemical structure of gel particles. It can be concluded that vacuum freeze-dried method could significantly increase the specific surface area, pore size and tungsten content of gel particle. In order to decrease the content of 188W in the elute, a handful of acidic alumina was filled in the bottom of our 188W-188Re generator, an elution and purification integrated-generator was formed. During the first five processes, the nuclear purity of 188Re solution was above 99.99%, the radiochemical purity was approximately 99.5%, the pH value was 5.0–7.0 and the average elution efficiency reached up to 82.7%. In addition, the leakage rate of 188W was low as 1.60 × 10−6, and the peak of elute curve was located at 2 mL without the trailing phenomenon. This work lays a solid foundation for the domestic demand of daughter nuclide 188Re, further makes an outstanding contribution to the application of the radiation therapy technology and the protection of people's health.

PROSPECTS FOR USING A COBALT CATALYST FOR FISHER-TROPSCH SYNTHESIS BASED ON SYNTHETIC SILICA ALUMINA

The possibility of the use of commercially available silica-alumina hydrate Siral-40, containing 40 wt.% of SiO2, in the composition of a composite cobalt Fischer–Tropsch synthesis (FTS) catalyst was studied. The use of silica aluminas may become a new promising direction in the development of catalysts for a shortened technological chain based on the use of bifunctional catalysts that make it possible to eliminate the hydroprocessing stage. In addition, such catalysts can be useful for expanding the range of products obtained, including those unconventional for single-reactor Fischer–Tropsch synthesis. The initial silica alumina powder was pretreated in air flow at different temperatures to adjust the concentration of acid cites on its surface. The initial and calcined powders were studied using X-ray diffraction analysis, IR spectroscopy and sorption methods. The catalysts were investigated by diffraction and sorption methods. It has been shown that an increase in the calcination temperature of the initial Siral-40 powder leads to a decrease in the specific surface area and pore volume of catalysts based on it, with temperatures above 900 °C having the greatest effect. The synthesized catalysts were active in FTS, and the composition of the obtained C5+ hydrocarbons depended more on the properties of the Siral-40 powder than the catalytic performance. The composition of C5+ hydrocarbons, obtained in the presence of all investigated catalysts contained at least 60% of diesel fraction and more than 30% of wide base oil fraction. Thus, synthetic amorphous silica aluminas are a promising component for new Fischer–Tropsch synthesis catalysts, which make it possible to obtain a wide range of products without the use of a deep hydroprocessing stage in the technological chain. For citation: Sineva L.V., Asalieva E.Yu., Gryaznov K.O., Mordkovich V.Z. Prospects for using a cobalt catalyst for Fisher-Tropsch synthesis based on synthetic silica alumina. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 10. P. 88-98. DOI: 10.6060/ivkkt.20246710.7y.

Oxidation of Geraniol on Vermiculite—The Influence of Selected Parameters on the Oxidation Process

Geraniol is a compound belonging to the group of monoterpenes that finds many applications in organic syntheses, medicine and cosmetics. The following properties of geraniol and its derivatives are of particular interest in medicine: its anti-inflammatory, antioxidant, antimicrobial and anticancer effects. The geraniol oxidation process was carried out using a mineral of natural origin—vermiculite. Vermiculite is a catalyst that perfectly fits into modern trends in the organic industry, where the aim is to use cheap, renewable and relatively easily available catalytic materials (vermiculite is found on continents including Africa, North America, South America, Australia and Asia). Preliminary studies on the oxidation process of geraniol on vermiculite was carried out in a glass apparatus using molecular oxygen supplied by means of a bubbler and magnetic stirrer with a heating function. During the oxidation process of geraniol on vermiculite, the influence of the following parameters was examined: the temperature, amount of catalyst and reaction time. The main parameters of the process, on the basis of which the most favorable process conditions were selected, were the selectivity of the transformation to 2,3-epoxygeraniol, citral and 2,3-epoxycitral, and the conversion of geraniol. The composition of the post-reaction mixtures was determined qualitatively and quantitatively using the gas chromatography method. In addition, vermiculite was subjected to instrumental tests, such as XRD, SEM, EDX, FTIR and UV-VIS. Moreover, the specific surface area, pore volume and pore volume distribution were estimated on the basis of N2 sorption at −196 °C and also the acid-site concentration in vermiculite was established.

Chemical Safety Assessment of Pitch-Based Activated Carbon Pellets via Highly Toxic Gas Adsorption Properties

This study focuses on the preparation of activated carbon using a petroleum-residue-based pitch, as well as the HCl gas adsorption properties of the resulting activated carbon pellets relative to their specific surface area and pore structure. Activated carbon was prepared under various oxidation and chemical activation conditions using pitch with a softening point of 220 °C. The activated carbon was mixed with distilled water, an acrylic binder, and carboxymethyl cellulose in a specific ratio to form pellets. These pellets were then dried in an oven at 80 °C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analyses were performed to evaluate the surface structure and specific surface area of the finalized pellets. HCl gas was adsorbed at a concentration of 50 ppm while examining the adsorption characteristics relative to the pore structure and specific surface area.

Effect of carbonaceous materials on phosphorus removal in flow-through packed column systems.

Phosphorus (P) overloading in aquatic environments has long-been recognized as the leading cause of water quality deterioration, harmful algal bloom, and eutrophication. This study investigated P removal performance by five cost-effective carbonaceous materials (CMs) in flow-through packed column systems. These CMs include biochars pyrolyzed from feedstocks of Eucalyptus (E-biochar) and Douglas fir (D-biochar), commercial biochar (C-biochar), iron oxide-coated biochar (Fe-biochar), and commercial activated carbon (AC). The physicochemical properties of CMs, such as specific surface area (SSA), pore volume, pore diameter, elemental composition, and surface charge, were characterized. The packed column experimental results showed that P removal performance followed the order: E-biochar < D-biochar < C-biochar < Fe-biochar < AC. Specifically, the sorption capacity of 1mg/L of P in packed columns was 0.0036mg P/g E-biochar, 0.0111mg P/g D-biochar, 0.0369mg P/g D-biochar, 0.077mg P/g Fe-biochar, and 0.088mg P/g AC, respectively. The largest SSA (1012 m2/g) and pore volume (0.57 cm3/g) of AC accounted for the most outstanding P removal efficiency mainly by physical sorption, while electrostatic interaction explained the high P removal by Fe-biochar (SSA as low as 32.4 m2/g). Our findings provide direct practical implications for effectively removing P in water by cost-effective CMs.

Clays-based geopolymers: a sustainable application as adsorbent of cytostatic drugs for water purification

The administration of cytostatic drugs in chemotherapy is steadily increasing, triggering thus a risk to the environment. Identifying powerful ways to effectively remove these hazardous pollutants from hospital and effluent wastewater before they discharge into the aquatic environment remains a critical and challenging task. Adsorption is among the most effective ways to treat contaminated water due to the wide availability and selectivity of the adsorbents besides the simplicity and the low start-up costs of the technique. In this work, a geopolymer, elaborated from an illito-kaolinitic clay (Douiret region of Tunisia) and industrial waste (silica fume and phosphogypsum), has been tested as promising decontamination of the cytostatic drugs paclitaxel (PCX) and irinotecan (IRI) from water samples. The foamed geopolymer was characterized using X-ray diffraction, Fourier transform infrared, scanning electron microscopy and thermogravimetric analysis before and after adsorption. Adsorption batch assays were performed using different concentrations of PCX and IRI, contact times and environmental conditions. The geopolymer had an excellent removal efficiency (almost 100% for PCX and 89% for IRI) using 20 mg of adsorbent and 2.5 mg/L of each drug concentration. The characterization results showed that cytostatic drugs were adsorbed to the geopolymer through physical interactions, pore filling, electrostatic attraction and hydrogen bonding. The specific surface area and pore volume of the geopolymer were 82.23 m2/g and 0.19 cm3/g, respectively. In addition to its cost-effective properties, the geopolymer demonstrated excellent efficiency in contaminated natural samples (including influent, effluent wastewater and surface water) denoting a great application for water purification.

Structural design and performance correlation of porous Poly(ionic liquid)S for 2-bromophenol adsorption

The demand for bromophenol is on the rise, driven by its extensive applications in industries, including human medicine. This surge in demand has spurred the development of eco-friendly methods for bromophenol recovery and the synthesis of new, low-toxicity compounds. In our study, we prepared a novel poly(ionic liquid) (PIL) featuring a benzene ring. The synthesis of this PIL involved using benzyl alcohol as the primary crosslinking agent, dimethoxymethane as an auxiliary crosslinking agent, and an imidazolium-based ionic liquid monomer, [Dimbb]Cl₂, for the adsorption of 2-bromophenol from aqueous solutions. We designed the PIL to be a high-performance and sustainable adsorbent by optimizing its specific surface area and pore structure. Structural analysis revealed that the PILs have a highly rich micro-mesoporous structure. The adsorption kinetics conformed to pseudo-second-order kinetics, reaching equilibrium in just 6 min. According to the Langmuir model, PIL-1 demonstrated a remarkable maximum adsorption capacity of 434.71 mg/g for 2-bromophenol. Quantum chemical calculations suggested that the adsorption mechanism involves processes such as pore filling, hydrogen bonding, electrostatic interactions, and π-π interactions. Furthermore, the adsorbent can be effectively recovered at least five times using anhydrous ethanol as the desorption agent, while maintaining an adsorption efficiency exceeding 90 %.

Hydrothermally synthesized nitrogen-doped hydrochar from sawdust biomass for supercapacitor electrodes

Porous carbon generated from biomass is among the most promising electrode materials for supercapacitor applications. In this research work, sawdust was used as a carbon source to synthesize N-doped hydrochars via the hydrothermal method in the presence of nitrogen-containing compounds including ammonium chloride, urea agar, ammonium molybdate tetrahydrate, and mammalian urine, followed by chemical activation by potassium hydroxide. Using the hydrothermal technique, it was possible to dope 7.06 wt% of nitrogen into the hydrochar. The as synthesized materials were characterized by TGA/DTA, FTIR, BET, XRD, SEM/EDS, XPS, and proximate analysis. Furthermore, EIS, CV, and GCD were used to assess electrochemical performance. All the N-doped hydrochars synthesized samples possess crystalline and mesoporous structures with hydroxyl and amide functional groups. The KOH activation improved the specific surface area and pore volume by 8.5 % and 21 %, respectively. The maximum specific surface area and pore volume were found to be 560.72 m2/g and 0.2246 cc/g, respectively. The CV findings demonstrate the battery-like characteristics of the electrocatalysts made with molybdenum (VI) oxide (MoO3) embedded in these N-doped hydrochars, yielding 35.16 F/g specific capacitance at 10 mV/s. In contrast, the GCD's specific capacitance displays 80 F/g at 0.5 Ag−1.

Biochar-based fertilizers from co-pyrolysis of algae and hazelnut shell with triple superphosphate: Physicochemical properties and slow release performance.

Phosphorus (P) is a vital nutrient for plant growth and food production. Excessive amounts of P fertilizers to a greater extent of crop P offtake are inevitably applied due to low utilization efficiency, causing environmental pollution. This study aimed to evaluate biochar-based fertilizers (BBFs) produced by co-pyrolyzing algae (A) and hazelnut shell (H) biomasses with triple superphosphate (TSP) at a ratio of 4:1 (w/w). The potential of the slow-release performance of BBFs was studied during kinetics experiments. The co-pyrolysis of biomasses with TSP yielded BBFs with significantly different properties, including electrical conductivity, pH, elemental ratios, functional groups, specific surface area and pore size characteristics. Phosphorus release from all biochars and BBFs followed the Elovich model, except for TSP and H+TSP. Kinetic studies revealed prolonged P-release times and slower release rates for BBFs compared to conventional TSP. So that, TSP released 100% of the total P, whereas H+TSP and A+TSP biochars released only 3.14% and 5.14% of the total P, respectively, during a 240-hour experiment. The slow-release performance of BBFs suggests their potential as promising alternatives to conventional phosphate fertilizers. BBFs have the potential to enhance P utilization efficiency, increase crop yield and mitigate the environmental impact of P fertilizer runoff.

Nano-Metal-Organic Frameworks and Nano-Covalent-Organic Frameworks: Controllable Synthesis and Applications.

Nanoscale framework materials have received much attention due to their diverse morphologies as well as good properties, and synthetic methods to construct different dimensions have been reported. Therefore, the study of the relationship between different sizes, dimensions and properties has become a hot research topic. This article provides a comprehensive examination of the controllable synthesis strategies of nano-metal-organic frameworks (nano-MOFs) and nano-covalent-organic frameworks (nano-COFs) and their applications in energy storage and catalysis. Commences with an overview of the synthetic evolution of nanoscale framework materials, which have garnered attention due to their exceptional specific surface area, regular pores, and tunable structural functionality. Various preparation methods for 0D, 1D, 2D and 3D nanostructures are then highlighted. These synthesis strategies not only improve the stability and activity of the materials, but also provide a basis for the design of novel energy storage and catalytic materials. Furthermore, the article presents an overview of the recent advancements in the field of energy storage and catalysis, with a particular focus on the applications of nano-MOFs/COFs in zinc-, lithium-, and sodium-based batteries as well as supercapacitors. ​.

Polyoxometalates@Metal-Organic Frameworks: Synthesis Strategies, Nanostructure Modulation and Application in Biomass Conversion.

Polyoxometalates@metal-organic frameworks (POMs@MOFs) have attracted much attention as multifunctional materials in biomass catalysis. Individual POMs and MOFs are hindered by their respective defects, such as poor stability and single catalytic active site, which make it difficult to realize large-scale applications. However, the combination of POMs and MOFs can be used to maximize the catalytic advantages of each. MOFs with high specific surface area and rich pore structure can effectively stabilize and uniformly disperse POMs, while the introduction of POMs also provides more catalytic possibilities for POMs@MOFs. Therefore, POMs@MOFs with ultra-high porosity, large specific surface area and excellent acid catalytic activity have unique catalytic advantages in the field of biomass catalytic conversion. In this work, we provide an overview of the current development of POMs@MOFs in the field of biomass catalysis. The synthesis strategies of POMs@MOFs are summarized and discussed, highlighting the in-situ synthesis methods. We focus on the nanostructure engineering of POMs@MOFs, and explore the "structure-property" relationship in depth. In addition, the representative work of POMs@MOFs in the catalysis of biomass derivatives is summarized. Filially, the prospects, and challenges for the future development of POMs@MOFs in the field of biomass catalysis are also presented.

S-Cu Doubly Doped NiFe LDH@Diatomite with Adjustable Surface Characteristics for the Efficient Removal of Tetracycline.

Overuse of antibiotics can lead to increased bacterial resistance; therefore, there is a need to develop efficient nanomaterials for removing antibiotics from water. NiFe bimetallic hydroxide nanosheets doped with S-Cu were prepared on diatomite (S-CuNiFe LDH@diatomite) by using a two-step hydrothermal method. The surface of CuNiFe LDH@DE has a layered structure with an increased specific surface area and pore volume. The average pore size of S-CuNiFe LDH@De increases from 13.3 to 24.7 nm, and a more stereoscopic channel structure is obtained. Tetracycline removal experiments were performed on CuNiFe LDH@De and S-CuNiFe LDH@De. It was found that CuNiFe LDH@De had excellent photocatalytic performance and S-CuNiFe LDH@De had excellent adsorption performance. After CuNiFe LDH@De had been in contact with tetracycline (TC) for 2 h, the TC removal rate reached 95.6%. After S-CuNiFe LDH@De had been in contact with TC for 1 h, the adsorption capacity of TC was 145.5 mg/g. The pseudo-first-order kinetics and Sips isotherm model can be used to describe the adsorption process more accurately. The response surface method was used to optimize the adsorption conditions. According to the optimized conditions, a better adsorption performance of 166.9 mg/g was obtained. The two prepared materials showed good performance in the removal of tetracycline. This study provides a way to synthesize low-cost adsorbents and photocatalysts, which has value in the treatment of TC wastewater.

Structural characteristics and biological evaluation of copper coating cotton material obtained by chemical reduction method

The article describes the preparation of new cotton materials obtained by chemical deposition of copper sulfide. This two-stage process consists of chelation of copper sulfate on cellulose chains of cotton (COT → COT-CuSO4) with subsequent precipitation of copper in the form of copper sulfide (COT-CuSO4 → COT-CuS) using sodium sulfide. The obtained COT-CuS composites were characterized physicobiologically. Thus, the structural characteristic of the Cotton-CuS material was determined by microscopy analysis (SEM), Atomic Absorption Spectrometry with Flame Excitation (FAAS), specific surface area and total pore volume analysis (BET). The copper functionalized cotton fabric was subjected to microbial activity tests against colonies of Gram-negative (Escherichia coli) and Gram-positive ( Staphylococcus aureus) bacteria and Chaetomium globosum, Aspergillus niger fungal molds species. Biochemical evaluation includes hematological tests of activated partial thromboplastin time (aPTT) and prothrombin time (PT). The substantial antimicrobial properties of the newly synthesized COT-CuS material with the lack of influence on blood coagulation processes offer prospects of a potential use as applications as an antibacterial/antifungal material.

Decoupling study of municipal solid waste gasification: Effect of pelletization on pyrolysis and gasification of pyrolytic char

To explore the influence of pelletization on the thermal conversion of municipal solid waste (MSW), pyrolysis characteristics and gasification reactivity of MSW pellet and powder were investigated in this study. Besides, the physicochemical properties of internal char and external char within the char pellet were separately characterized. Moreover, the relationship between the physicochemical properties of char pellet and its gasification reactivity was clarified. Results showed that the pyrolytic gas yields of MSW pellets were increased by 15.47 % and 11.55 % at 700 °C and 800 °C, respectively, compared to powder MSW. It was mainly attributed that the conversion of monocyclic aromatic hydrocarbons to polycyclic aromatic hydrocarbons was promoted by the longer residence time within the pellets. Meanwhile, the physicochemical properties of pyrolytic char pellets exhibited a significant heterogeneity. Specifically, the number of ordered aromatic rings of char pellet was reduced, while the order degree of carbon structure was enhanced, particularly the internal char. However, the difference magnitude between internal and external char was diminished with temperature. This was due to the higher temperature resulting in a larger surface specific area and pore volume of the char pellet, especially the internal char, thereby enhancing the pyrolysis process. Furthermore, an increase in pore volume within the char pellet improved gasification reactivity when the conversion rate > 0.4. These findings provide a reference for the pyrolysis and gasification process of MSW pellets.

Optimized pyrolytic synthesis and physicochemical characterization of date palm seed biochar: unveiling a sustainable adsorbent for environmental remediation applications.

This study focuses on the optimization and comprehensive characterization of biochar synthesized from date palm seeds (DPS), a prevalent agricultural waste in arid regions. Using response surface methodology (RSM) with a central composite design (CCD), we optimized the pyrolysis process by investigating the effects of time (1-3 h) and temperature (600-900 °C) on critical properties such as specific surface area, pore volume, and yield. The optimized biochar, produced at 828 °C for 1.7 h, demonstrated a high specific surface area of 654.8 m2/g and well-developed microporosity. Characterization techniques, including XRD, FTIR, SEM-EDS, and BET analyses, revealed an amorphous carbon structure with graphitic domains, diverse surface functionalities, and a heterogeneous porous microstructure. The biochar's point of zero charge at pH 7.58 indicates its potential for selective adsorption of charged contaminants. The close agreement between RSM-predicted and experimental values for specific surface area (652.1 m2/g vs. 654.8 m2/g) and micropore volume (0.191 cm3/g vs. 0.190 cm3/g) validates the effectiveness of the model in optimizing biochar properties. This research highlights the potential of DPS-derived biochar as a sustainable adsorbent for environmental remediation, opening avenues for valorizing agricultural wastes and contributing to circular economy principles.

Enhancing chemical heat storage performance of nanocarbon porous particle based MgO/Mg(OH)2 composite by calcination method

The application of MgO/Mg(OH)2 in heat storage technology has been limited due to slow hydration rate and easy agglomeration. In this paper, nanoporous carbon particle (NCP) as a carrier was used to prepare NCP/MgO chemical heat storage composite materials by impregnation and calcination methods, respectively. The microstructure characterization, hydration reaction, and simultaneous thermogravimetric analysis experiments were carried out on the prepared composite materials. The results showed that the internal distribution of MgO in the composite material prepared by calcination method was more uniform, and the particle size of MgO was smaller. Under the conditions of 110 ℃ hydration temperature and 57.8 kPa water vapor partial pressure, the hydration conversion ratio of the composite material prepared by calcination method after 120 min of hydration conversion ratio reached 93 %, which was 17.7 % higher than that of the impregnated composite material and 50 % higher than that of pure MgO. Under the comprehensive influence of specific surface area, pore structure, and active component particle size, compared with pure materials and impregnated composite materials, the dehydration rate of the composite material prepared by calcination method at 300 ℃ was twice that of impregnated method and 6 times that of pure MgO, and the heat storage density reached 1039kJ/kg. After 10 cycles, the heat storage density still maintained an initial state of 95.8 %. Compared with pure materials and impregnated composite materials, NCP/MgO composite materials prepared by calcination method had better heat storage performance and higher cyclic stability.

Layered double hydroxides/biochar composites for adsorptive removal of tetracycline and ciprofloxacin

Modification of biochar (BC) using layered double hydroxides (LDHs) is an anticipated strategy to strengthen the adsorption performance of BC. In this work, sawdust was used to prepare pristine BC to act as a matrix, and the MgFe-LDHs were selected as typical LDHs to prepare BC-LDHs composites via a coprecipitation technique, and the adsorption mechanisms toward tetracycline (TC) and ciprofloxacin (CIP) were evaluated. The effect of LDHs amount on the characteristics of BC-LDHs composites and the adsorption behavior and mechanisms of TC and CIP were also studied. Results showed that the loading of LDHs reduced the specific surface area and total pore volume of BC but developed more mesoporous structure in composites, created metal oxygen-containing functional groups (Mg–OH, Mg–O, Fe–O), and introduced a typical mineral (Mg6Fe2(OH)16CO3·4H2O) on the surface of the BC. The BC-1/3LDHs obtained by loading LDHs on 3 g BC exhibited the maximum adsorption capacity toward TC and CIP, and reached 77.04 mg∙g−1 and 66.74 mg∙g−1, respectively. The introduction of MgFe-LDHs greatly intensified the complexation interaction and hydrogen bonding of the composites. The Freundlich and pseudo-second-order models well-described the adsorption process of TC and CIP on BC-1/3LDHs. In addition, BC-1/3LDHs could adsorb TC and CIP in a wide range of pH values despite the interference of coexisting ions and also presented a good recycle utilization potential. Furthermore, the introduction of LDHs, especially BC-1/3LDHs, shifted the adsorption thermodynamic properties of BC. Overall, the prepared BC-1/3LDHs could be used as a promising adsorbent for the removal of TC and CIP from water environments.

Supercapacitor electrodes derived from ultra-high surface area activated carbon spheres synthesized by fluidized activation

This study thoroughly investigated the effects of activation conditions on pore structure development using response surface methodology with a central composite design. The activated carbon sphere (ACS) derived from phenolic formaldehyde resins by carbonization and fluidized activation was examined and characterized. The pore size distribution of ACS samples was all in the microporous and mesoporous scales. ACS with an ultra-high specific surface area of 3142 m2 g−1 and total pore volume of 1.513 cm3 g−1 was successfully obtained at 900 °C for 4 h. Electric double-layer capacitor (EDLC) electrodes derived from ACS with different activation conditions were examined by using cyclic voltammetry and galvanostatic charge/discharge to comprehend the influence of surface area, pore volumes, and the amount of binder on the electrochemical performance. The optimal EDLC electrode was obtained using ACS with the largest specific surface area and pore volume with 5 wt% of binder addition. The specific capacitance was 143.7 F g−1 in a 1 M H2SO4 solution. The cyclical stability of the carbon electrode was also examined under 5000 cycles, and the charge/discharge efficiency remained nearly 100 % without deterioration. This study provides insights into fabricating ultra-high surface area ACS and their potential application as supercapacitors.