Effect Of Specific Surface Area Research Articles

Direct Affinity Ligand Immobilization onto Bare Iron Oxide Nanoparticles Enables Efficient Magnetic Separation of Antibodies.

Magnetic separation is a promising alternative to chromatography for enhancing the downstream processing (DSP) of monoclonal antibodies (mAbs). However, there is a lack of efficient magnetic particles for successful application. Aiming to fill this gap, we demonstrate the suitability of bare iron oxide nanoparticles (BION) with physical site-directed immobilization of an engineered Protein A affinity ligand (rSpA) as an innovative magnetic material. The rSpA ligand contains a short peptide tag that enables the direct and stable immobilization onto the uncoated BION surface without commonly required laborious particle activation. The resulting BION@rSpA have beneficial characteristics outperforming conventional Protein A-functionalized magnetic particles: a simple, fast, low-cost synthesis, a particle size in the nanometer range with a large effective specific surface area enabling large immunoglobulin G (IgG) binding capacity, and a high magnetophoretic velocity advantageous for fast processing. We further show rapid interactions of IgG with the easily accessible rSpA ligands. The binding of IgG to BION@rSpA is thereby highly selective and not impeded by impurity molecules in perfusion cell culture supernatant. Regarding the subsequent acidic IgG elution from BION@rSpA@IgG, we observed a hampering pH increase caused by the protonation of large iron oxide surfaces after concentrating the particles in 100 mM sodium acetate buffer. However, the pH can be stabilized by adding 50 mM glycine to the elution buffer, resulting in recoveries above 85% even at high particle concentrations. Our work shows that BION@rSpA enable efficient magnetic mAb separation and could help to overcome emerging bottlenecks in DSP.

In Situ Growth 3D GDY-NCNTs Nanocomposites for High-Performance Supercapacitors.

New binary carbon composites (GDY-NCNTs and GDY-CNTs) with a three-dimensional porous structure, which are synthesized by an in situ growth method, are adopted in this article. The GDY-NCNTs composites exhibit excellent specific capacitance performance (679 F g-1, 2 mV s-1, 139% increase compared to GDY-CNTs) and good cycling stability (with a capacity retention rate of up to 116% after 10000 cycles). The three-dimensional porous structure not only promotes ion transfer and increases the effective specific surface area to improve its specific capacitance performance but also adapts to the volume expansion and contraction during the charging and discharging process to improve its cycling stability. The presence of nitrogen doping in the carbon nanotubes of GDY-NCNTs increases the surface defects of the composites, provides more electrochemical points, and improves the surface wettability of the composites, further improving the electrochemical performance of the composites.

Effect of Heat Treatment on Hygroscopicity of Chinese Fir (Cunninghamia lanceolata [Lamb.] Hook.) Wood

Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) is a widely planted species of plantation forest in China, and heat treatment can improve its dimensional stability defects and improve its performance. The wood samples were heat-treated at various temperatures (160, 180, 200, and 220 °C) for 2 h. To clarify the effect of heat treatment on wood hygroscopicity, the equilibrium moisture content (EMC) was measured, the moisture adsorption and desorption rates were determined, the hygroscopic hysteresis was examined, and the Guggenheim, Anderson, and de Boer (GAB) model was fitted to the experimental data. The moisture absorption isotherms of all samples belonged to the Type II adsorption isotherm, but the shape of the desorption isotherm was more linear for heat-treated wood samples, especially when the heat treatment temperature was higher. According to the results analyzed with ANOVA, there were significant differences in equilibrium moisture content between the control samples and the heat-treated samples under the conditions of 30%, 60%, and 95% relative humidity (RH, p < 0.05), and the results of multiple comparisons were similar. The decrease in hygroscopicity was more pronounced in wood treated at higher temperatures. The EMC of the 160–220 °C heat-treated samples of the control samples was 14.00%, 22.37%, 28.95%, and 39.63% lower than that of the control sample at 95% RH. Under low RH conditions (30%), water is taken up mainly via monolayer sorption, and multilayer sorption gradually predominates over monolayer sorption with the increase in RH. The dynamic vapor sorption (DVS) analysis indicated that the heat-treated wood revealed an increase in isotherm hysteresis, which was due to the change in cell wall chemical components and microstructure caused by heat treatment. In addition, the effective specific surface area of wood samples decreased significantly after heat treatment, and the change trend was similar to that of equilibrium moisture content.

Water distribution in pore systems and its influences on gas-bearing property of deep shale: A case study of the Longmaxi Formation in the Luzhou area, southern Sichuan Basin

The deeply-buried (>3500 m) Longmaxi Formation (LMX) shale in the southern Sichuan Basin, China, has become an attractive target for shale gas exploration owing to its huge resource potential. Exploration shows that the deep shale has a wide range of gas-in-place (GIP) contents, with variable gas yields, but the reason remains unclear, especially the impact of pore water on gas-bearing property lacks systematic research. In the present study, a suite of deep LMX shale samples was collected from the well FB1 in the Luzhou area of the southern Sichuan Basin, and techniques such as the pore water content measurements, low-pressure gas (CO2 and N2) adsorption and high-pressure methane adsorption experiments of the moist and dry samples were employed to investigate the distribution of water in the nanopores and its effects on the gas-bearing property. The results show that the deep shale is characterized by a high water content, with a high water saturation (average up to 69.80%), and the water occurs in both the inorganic and organic pores. The water reduces the effective specific surface area and pore volume of the shale averagely by 79.01% and 22.56%. Consequently, the water results in the decrease of methane adsorption capacity averagely by 45.13%. The GIP content models of two typical shale samples indicate that their total gas content is < 3 m3/t under the actual conditions, without development potential, and it will increase significantly to >3 m3/t with decreasing water saturation to <40–50%, especially under overpressure conditions. The gas-bearing property of deep LMX shale reservoirs in the complex faulted zones or structural-complex zones would mainly depend on the pore water content except for the properties of shale itself (e.g., maturity, TOC content, mineral composition, porosity and pore structure).

Confining the Growth of AgNPs onto Epigallocatechin Gallate-Decorated Zein Nanoparticles for Constructing Potent Protein-Based Antibacterial Nanocomposites.

Sliver nanoparticles (AgNPs) have attracted tremendous interest as an alternative to commercially available antibiotics due to their low microbial resistance and broad-spectrum antimicrobial activity. However, AgNPs are highly reactive and unstable and are susceptible to fast oxidation. Synthesizing stable and efficient AgNPs using green chemistry principles remains a major challenge. To address this issue, we establish a facile route to form AgNP-doped zein nanoparticle core-satellite superstructures with ultralow minimum bactericidal concentration (MBC). In brief, polyphenol surface-functionalization of zein nanoparticles was performed, and the epigallocatechin gallate (EGCG) layer on zein nanoparticles served as a reducing-cum-stabilizing agent. We used EGCG-decorated zein nanoparticles (ZE) as a template to direct the nucleation and growth of AgNPs to develop metallized hybrid nanoparticles (ZE-Ag). The highly monodispersed core-satellite nanoparticles (∼150 nm) decorated with ∼4.9 nm AgNPs were synthesized successfully. The spatial restriction of EGCG by zein nanoparticles confined the nucleation and growth of AgNPs only on the surface of the particles, which prevented the formation of entangled clusters of polyphenols and AgNPs and concomitantly inhibited the coalescence and oxidation of AgNPs. Thus, this strategy improved the effective specific surface area of AgNPs, and as a result, ZE-Ag efficiently killed the indicator bacteria, Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus(MRSA) after 20 min of incubation, with MBCs of 2 and 4 μg/mL, respectively. This situation indicated that as-prepared core-satellite nanoparticles possessed potent short-term sterilization capability. Moreover, the simulated wound infection model also confirmed the promising application of ZE-Ag as an efficient antimicrobial composite. This work provides new insights into the synthesis and emerging application of AgNPs in food preservation, packaging, biomedicine, and catalysis.

Toward record high Zn2+ storage in carbon electrodes via pore confinement engineering

The effective specific surface area is proposed and well correlated with Zn2+ storage, guiding maximum Zn2+ storage within carbon. Multiple in situ spectroscopy techniques clarify the co-adsorption mechanism of hydrated Zn2+, SO42−, and H+.

Nano structured diatom frustules incorporated into TiO2 photoelectrodes to enhance performance of quasi-solid-state dye-sensitized solar cells

Diatom frustules are incorporated into multilayer photoelectrodes intending to enhance efficiency in dye-sensitized solar cells utilizing their light interaction properties. A specific, but ubiquitous in all oceans, pennate-type diatom frustules were used to form the composite layers. Single, double, and triple-layer photoelectrodes were constructed with pure TiO2 (control measurements) as well as with a TiO2/diatom frustule composite. The electrodes were prepared using TiO2 nanoparticles of two sizes (13 and 21 nm) and were analyzed using UV visible absorption and XRD spectra. The morphology of frustules and electrodes were analyzed using scanning electron microscopy. The performance for each photoanode configuration was measured by assembling photoelectrochemical solar cells fabricated with a Pt counter electrode and a gel polymer electrolyte that excludes volatile solvents. The efficiency of the control cell is 3.37%. After replacing the topmost TiO2 layer with a TiO2/diatom frustule composite layer, efficiency increases to 6.78%. This is an impressive efficiency enhancement of 101%. The short circuit current density of frustule-incorporated three-layer cells is 18.1 mA cm−1 while for the control cell it is 8.98 mA cm−1. The enhanced efficiency of cells made with TiO2/diatom frustule composite electrodes and a polyethylene oxide-based gel polymer electrolyte can be attributed to the improved light absorption by the photoanode due to optical scattering and light-trapping effects caused by the presence of diatom frustules. Frustules also can assist in enhancing dye adsorption by increasing the effective specific surface area of the composite photoelectrode due to their nanoporous structure.

Inhibiting the Leidenfrost Effect by Superhydrophilic Nickel Foams with Ultrafast Droplet Permeation.

Inhibiting the Leidenfrost effect has drawn extensive attention due to its detrimental impact on heat dissipation in high-temperature industrial applications. Although hierarchical structures have improved the Leidenfrost point to over 1000 °C, the current performance of single-scale structures remains inadequate. Herein, we present a facile high-temperature treatment method to fabricate superhydrophilic nickel foams that demonstrate ultrafast droplet permeation within tens of milliseconds, elevating the Leidenfrost point above 500 °C. Theoretical analysis based on the pressure balance suggests that these remarkable features arise from the superhydrophilic property, high porosity, and large pore diameter of nickel foams that promote capillary wicking and vapor evacuation. Compared to solid nickel surfaces with a Leidenfrost temperature of approximately 235 °C, nickel foams nucleate boiling at high superheat, triggering an order of magnitude higher heat flux. The effects of the pore diameter and surface temperature on droplet permeation behaviors and heat transfer characteristics are also elucidated. The results indicate that droplet permeation is dominated by inertial and capillary forces at low and high superheat, respectively, and moderate pore diameters are more conducive to facilitating droplet permeation. Furthermore, our heat transfer model reveals that pore diameter plays a negligible role in the heat flux at high surface temperatures due to the trade-off between effective thermal conductivity and specific surface area. This work provides a new strategy to address the Leidenfrost effect by metal foams, which may promise great potential in steel forging and nuclear reactor safety.

A magnetic recyclable MCM-48/ZnFe2O4/BiOBr heterojunction with improved RhB visible light degradation efficiency

The MCM-48/ZnFe2O4/BiOBr (MZBB) heterojunction photocatalyst was constructed and applied to decompose rhodamine B (RhB) under the influence of visible light to investigate its photocatalytic effect. The outcomes revealed that 0.75 MZBB compound semiconductor degraded RhB dye at a concentration of 40 mg/L, pH 6.0, by 99.03% after 60 min, and the total organic carbon (TOC) mineralization rate was 0.0631. The combination of n-type ZnFe2O4 and BiOBr is responsible for the increased photocatalytic performance of the MCM-48/ZnFe2O4/BiOBr composite, and the presence of n-n junctions promotes the separation of photogenerated carriers and prolonged reorganization time. In addition, MCM-48 has good absorption properties and effective specific surface area. The present work accomplished the dual challenges of constructing MCM-48 and ZnFe2O4 on flower-like BiOBr and reusing fly ash. The material shows an excellent ability to decompose organic pollutants and magnetically recoverable.

An easy CTAB-assisted path towards bayberry-like Ni–Co–Mn ternary hydroxide with enhancing supercapacitor performance

In this study, we synthesized a bayberry-like Ni–Co–Mn ternary hydroxide with a secondary nanoneedle structure using a modified and cost-effective hydrothermal process assisted by the surfactant cetyltrimethylammonium bromide (CTAB). The incorporation of CTAB and graphene in the preparation process significantly enhances the electrochemical performance of NiCoMn–OH. The achieved results are truly impressive, with a high specific capacity of 1450 ​F ​g−1 and an outstanding capacity retention of 52.57% over 5000 cycles. The superior performance could be attributed to the specific bayberry-like microstructure with high effective specific surface area, which allowed for facile and rapid transport of ions and electrons. Moreover, the synergistic effect of CTAB and graphene proved to be crucial in stabilizing the Co2+ and Mn2+ ions within the ternary hydroxide structure. We developed a hybrid capacitor using a NiCoMn–OH-CTAB/Graphene composite electrode and an active electrode, which delivered a superior energy density of 50.79 ​Wh kg−1 at a power density of 400 ​W ​kg−1 and a cycling stability of 60.37% after 10000 cycles. These results indicate that the NiCoMn–OH-CTAB/Graphene composite electrode has great potential as an electrode material for energy storage devices.

Enhanced capacitive performance by synergistic effect of interfacial functional groups and doping defects in honeycomb-like multi-chamber carbon

As a typical double-layer capacitive electrode material, carbon nanomaterials show desirable application potential in the field of capacitive deionization (CDI) and supercapacitors (SCs). In this work, interfacial functional groups and B\\O co-doping defects are simultaneously introduced into multi-chamber carbon with confinement effect, and their practical applications in CDI and flexible capacitors are also studied. Specifically, the oxygen-rich carbon source and boron source, dissolved and mixed completely via co-crystallization method, released amount of gas during the pyrolysis process to produce multi-chamber honeycomb-like carbon with ultrathin walls, which were further introduced into abundant interfacial functional groups by dopamine to optimize the carbon surface. At the same time, part of boron atoms entered the carbon lattice to form boron doping at high temperature, followed by the integration with the oxygen heteroatoms in carbon source to generate abundant boron and oxygen codoping defects. The as-prepared diatomic defects by the synergistic effect promote the wettability and pseudocapacitance of the material. In addition, the derived carbon materials are endowed with good hydrophilic ability and surface activity under the modification of dopamine functional groups. The ideal hydrophilic ability ensures that the porous structure of material can be infiltrated by electrolyte to provide large effective specific surface area, which enhances the electrical double-layered capacity. The interfacial functional groups also offer additional pseudocapacitance, so as to improve the ion adsorption capacity of PDA-BOC.

The Impact of Mesoporous Silica Nanoparticles on Electrochemical Performance

Mesoporous silica nanoparticles were synthesized via sol–gel method to produce uniform size nanoparticles using n-Octadecyl-trimethoxy silane which gives a good dispersion of silica nanoparticles in hydrophobic mediums. Scanning electron microscopy (SEM), infrared spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis, and nitrogen adsorption-desorption tests were used to thoroughly investigate the nanocomposites' morphology and structure. BET results show a high surface are of 760 m2/g and specific high pore size (30Ȧ) and pore volume (0.336 cm3/g). The SEM results present that the mesoporous silica nanoparticles possess a well dispersed and uniform particle morphology and FTIR interpenetrating the well-prepared silica nanoparticles which possess Si-O-Si and Si-O bond. The XRD analysis confirmed the amorphous nature silica nanoparticles. The electrochemical properties of silica nanoparticles were evaluated in a potassium chloride solution. With the advantages of a large specific surface area and a suitable pore size distribution, a pair of broad and symmetric redox peaks centred at -0.15 V and 0.6 V appears. Mesoporous silica with a large effective specific surface area demonstrated excellent electrochemical performance, making them excellent candidates for supercapacitors and fuel cells.

Excellent electrochemical performance of porous carbon by in situ nitrogen-doped derived from polyurethane

In this work, the application of high specific surface area nitrogen-doped porous carbon prepared from polyurethane (TPUC) as a supercapacitor electrode is reported. Five samples are prepared with KOH as activator at different activation temperatures and applied to research the electrochemical properties of supercapacitor. The problems of uneven distribution and loss of nitrogen atoms are solved by in situ doping. The conductivity and wettability of activated carbon are improved by nitrogen-doped. The maximum specific capacitance (up to 527 F g−1 at 0.5 A g−1) and outstanding cycling stability (up to 342 F g−1 after 10,000 cycles) are obtained by the TPUC-800 sample (specific surface area of 3575 m2 g−1). These features are explained for the improvement of the effective specific surface area and the shortened ion diffusion distance in carbon electrode due to nitrogen-doped and the enhancement of hydrophilicity of carbon surface. The results reveal that such a simple strategy of nitrogen-doped polyurethane is an efficient way to prepare promising nitrogen-doped porous carbons for supercapacitor with good performance.

Flower-like WSe2 used as bio-matrix in ultrasensitive label-free electrochemical immunosensor for human immunoglobulin G determination.

The abnormal concentrations of human immunoglobulin G (hIgG) refers to many kinds of diseases. Analytical methods with the characteristics of rapid response, easy operation and high sensitivity should be designed to accurately determinate the hIgG levels in human serum. In this work, a label-free electrochemical immunosensor based on WSe2/rGO was developed to sensitively detect human immunoglobulin G. First, the flower-like transition metal dichalcogenides (TMDCs) Tungsten Diselenide (WSe2) with large effective specific surface area and porous structure was synthesized by hydrothermal synthesis. As a bio-matrix, the flower-like WSe2 efficiently increased the active sites for loading antibodies. Meanwhile, reduced graphene oxide (rGO) obtained by tannic acid reduction was used to improve the current response of the sensing interface. WSe2 was combined with rGO and the electrochemical active surface area (ECSA) of the sensing interface was enlarged to 2.1 times that of GCE. Finally, the combination of flower-like WSe2 and rGO broadened the detection range and reduced the detection limit of the sensing platform. The immunosensor exhibited a high sensitivity with a wide linear range of 0.01-1000ng/mL and low detection limit of 4.72pg/mL. The real sample analysis of hIgG were conducted under optimal conditions, and the spiked recovery rates were between 95.5 and 104.1%. Moreover, satisfactory results were obtained by testing the stability, specificity and reproducibility of the immunosensor. Therefore, it can be concluded that the as-proposed immunosensor has the application potential of clinical analyze of hIgG in human serum.

Potassium Hydroxide Activation as an Adsorbent for Equilibrium Isotherms of Hexavalent Chromium Adsorptions onto &lt;i&gt;Garcinia mangosteen&lt;/i&gt; Shell

The equilibrium isotherms of hexavalent chromium adsorption from water on potassium hydroxide (KOH) activated for mangosteen shell as an adsorbent by carbonization at 400 °C for 2 hours has been researched. The effective specific surface area of a biochar adsorbent is 164 m2/g, and its hexavalent chromium adsorption capacity can be encountered to be replied to on the pH 2.0 with initial feed concentration and temperature. The equilibrium adsorption isotherm models based on the Freundlich, Langmuir, Temkin, Hurkins-Jura, Halsay, Dubinin-Radushkevich, and Jovanovic models have been accompanied to compare the sorbate-sorbent system. The Freundlich isotherm model indicated a good fit with the experimental data for the system studied.

Polymetallic Clusters in Capacitive Deionization

Research and development of water purification technology can effectively alleviate the impact of water shortage. Capacitive deionization technology (CDI) is a novel water treatment technology, by applying low voltage, ions in solution are absorbed by electrodes to form double electric layers to remove pollutants in water. Electrode material is the main factor affecting the effect of CDI treatment. At present, the traditional CDI electrodes mainly focus on the research of carbon materials and carbon-based composites materials. However, their low effective specific surface area, complex preparation process and high resistance limit their application in practical wastewater treatment. Mixed metal oxides have become a new hotspot in the research and application of CDI electrode materials due to their excellent electrochemical properties, such as high reactivity, large specific capacitance and strong conductivity. However, there are few articles on its research and application in CDI. Therefore, this paper reviews the latest research progress, existing problems and application development of mixed metal oxide electrodes and their composite electrodes in the context of the types of polymetallic oxides.

Advanced treatment of industrial wastewater by ozonation with iron-based monolithic catalyst packing: From mechanism to application

An Fe-based catalyst was prepared by oxidising waste Fe shavings directly in a solution. In engineering applications, Fe shavings were compressed and modified to form Fe-based monolithic catalyst packing. Both of which exhibited excellent catalytic activity in catalytic ozonation industrial wastewater after biochemical treatment. Fe-based monolithic catalyst packing has irregular channels, large porosity, small pore diameter, and the effective specific surface area (SSA) up to 3500 m2/m3, these characteristics are conducive to mass transfer, and promote the effective utilisation of •OH in the catalyst “action zone”. A tower reactor (<3000 m3/d) and reinforced concrete construction reactor (>5000 m3/d) were designed according to the wastewater flow. Regression analysis showed that hydraulic residence time (HRT) and O3/CODin are important parameters in engineering design and operation. In addition, strategies for the application of Fe-based monolithic catalyst packing to wastewater with high salinity and high inorganic carbon concentration have been proposed. Fe-based monolithic catalyst packing catalytic ozonation is a relatively cost-effective and eco-friendly process with extremely broad application prospects in the advanced treatment of industrial wastewater.

Graphene Oxide-Wrapped Porous Hollow Co3O4 Microspheres with Enhanced Lithium Storage Performance

Porous hollow Co3O4 microspheres wrapped with graphene oxide were synthesized by a step solvothermal method and subsequent heat treatment. Benefiting from the design of special porous hollow microspheres, the effective specific surface area was greatly increased, the sufficient contact between the porous hollow Co3O4 microspheres and electrolyte was achieved, and then a charge specific capacity of 888.59 mA h g-1 was gained. Meanwhile, partial stress from the charging/discharging process was greatly relieved due to the abundant pores and hollow structure, excellent cycling stability was realized, and the charge specific capacity of the 1000th cycle was 465.75 mA h g-1 at 5 C (1 C = 890 mA g-1). In addition, the conductivity of Co3O4 microspheres was effectively improved due to the tight package of graphene oxide to Co3O4 microspheres, and superior rate performance was attained (280.99 mA h g-1 at 10 C).

Theoretical study of a novel porous penta-TaB with two-dimensional furrow surface as an anode for lithium-ion batteries

The transition metal boride five TaB anode material has small mass density, large effective specific surface area and high specific capacity. The two-dimensional wrinkled surface is favorable for the rapid diffusion of lithium ions.

In-situ growth microcircuits on bacterial membranes to enhance ion capture capability for capacitive deionization

The combination of biotechnology and artificial nanotechnology provide new breakthroughs in the design and manufacture of energy materials. In this work, the porous hollow hyphae carbon membrane with different thicknesses were acquired by biological cultivation approach, along with adsorbed Ni2+ as the in-situ growth points. Then, ultrafine hollow carbon tubes generated on the hyphae surface, forming multi-stage composite membrane (CNTs@MC) with tubules covering large tubes. Subsequently, rich amino functional groups were grafted onto MC (hyphae carbon membrane) surface to further improve its hydrophilicity and capacitance. In addition to the hollow structure, the hyphae carbon surface presents many small holes around 50 nm, which not only provides space for Ni2+ adsorption, but also favors the generation of double-layer capacitance. As secondary structure, ultrafine carbon nanotubes as microcircuits capture more charged ions on hyphae surface, thus offering better capacitance performance. The multistage hollow structure enhances the stability of material during ion adsorption. The grafted amino functional groups and intrinsic heteroatomic defects synergically enhance the wettability and pseudocapacitance of material. In general, large effective specific surface area, abundant surface amino functional groups and intrinsic heteroatomic defects guarantee the high capacitance of material, and also exhibits desirable performance in both solid-state supercapacitors and capacitive deionization applications.