Pore Diameter Research Articles

Engineering Trifluoromethyl Groups in Porous Coordination Polymers to Enhance Stability and Regulate Pore Window for Hexane Isomers Separation.

Effective separation of hexane (C6) isomers is critical for a variety of industrial applications but conventional distillation methods are energy-intensive. Adsorptive separations based on porous coordination polymers (PCPs) offer a promising alternative due to their exceptional porosity and tunable properties. However, there is still an urgent need to develop PCPs with high stability and separation performance. This study investigates how substituting a methyl (-CH3) group with a trifluoromethyl (-CF3) group can regulate pores and hydrophobicity in PCPs. This precise adjustment aims to enhance stability and improve the kinetic separation performance of hydrophobic C6 isomers by considering the size and hydrophobicity of the trifluoromethyl group. Two isostructural PCPs with pcu topology, PCP-CH3 and PCP-CF3, were synthesized to vary pore diameters and hydrophobicity based on the presence of -CH3 or -CF3 groups. PCP-CF3 showed greater stability in water compared to PCP-CH3. While PCP-CH3 had high adsorption capacities, it lacked selectivity, whereas PCP-CF3 demonstrated improved selectivity, particularly in excluding dibranched isomers. Dynamic column separation experiments revealed that PCP-CF3 could selectively adsorb linear and monobranched isomers over dibranched isomers at room temperature. These findings highlight the potential of fluorine-modified PCPs for efficient isomer separation and underscore the importance of stability improvement strategies.

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.

Modified Biochar Materials From Eucalyptus globulus Wood as Efficient CO2 Adsorbents and Recyclable Catalysts

AbstractHighly porous carbon materials derived from renewable resources constitute a promising and sustainable strategy regarding the enhancement of CO2 capture technologies. In this work, the valorization of Eucalyptus globulus wood, a forest invasive species present in European forests, is performed through its transformation in biochar. The deposition of nitrogen and different metals (aluminum, copper and chromium) onto biochar is performed, using the magnetron sputtering as a pioneering technique, to produce coated biochar nanoparticles with improved properties. The resultant modified biochar particles maintain a highly porous structure and present a remarkable CO2 adsorption capacity (up to 4.80 mmol g−1 for N@BC), which is attributed to the synergy of their large total surface area (527 m2 g−1) and microporosity (pore diameter = 21 Å), with a high content of nitrogen and oxygen heteroatom moieties (40.4% N, 11.4% O). Their application as heterogeneous bifunctional catalysts in CO2 cycloaddition to epichlorohydrin is performed, in the absence of any solvent or co‐catalyst, under moderate conditions (20 bar CO2, 120 °C), leading to good conversions (up to 58% conversion) and excellent selectivity for cyclic carbonates. Cu‐coated biochar is shown to be more stable than non‐modified material, being recycled and reused along 4 consecutive runs without loss of catalytic activity or selectivity.

Fabrication of Spherical Colloidal Supraparticles via Membrane Emulsification.

Colloidal supraparticles are micrometer-scale assemblies of primary particles. These supraparticles have potential application in photonic materials, catalysis, gas adsorption, and drug delivery. Thus, the synthesis of colloidal supraparticles with a narrow size distribution and high yield has become essential. Here, we demonstrate membrane emulsification as a high-throughput approach for fabricating spherical supraparticles with a narrow size distribution and control over particle size and crystallinity. Spherical supraparticles with well-ordered surface structures are synthesized by generating emulsion droplets of an aqueous colloidal dispersion in fluorocarbon oil using a Shirasu porous glass membrane followed by the consolidation of particles through water removal within the emulsion. We systematically investigate process parameters, including the flow rate of the particle dispersion, the particle concentration, and the average pore diameter of the membrane, on the mean size and size distribution of the supraparticles, revealing key factors governing supraparticle properties and production throughput. A comparative evaluation with commonly employed methods highlights the advantage of membrane emulsification, which combines well-defined internal structure and controlled supraparticle sizes with comparably high yields on the order of tens of grams per day. Importantly, in contrast to widely used droplet-based microfluidics, membrane emulsification allows fabrication of supraparticles in nonfluorinated oil. Overall, membrane emulsification offers a simple yet versatile method for fabricating colloidal supraparticles with high quality and yield and may serve as a bridge between existing high-precision techniques, such as droplet-based microfluidics, and high-throughput processes with less control, such as spray-drying.

Pore Structures in Detritusphere of Soils Under Switchgrass and Restored Prairie Vegetation Community

ABSTRACTRoot detritusphere, that is, the soil in the vicinity of decomposing root residues, plays an important role in soil microbial activity and C sequestration. Pore structure (size distributions and connectivity of soil pores) in the detritusphere serves as a major driver for these processes and, in turn, is influenced by the physical characteristics of both soil and roots. This study compared pore structure characteristics in the root detritusphere of soils of contrasting texture and mineralogy subjected to &gt; 6 years of contrasting vegetation: monoculture switchgrass and polyculture prairie systems. Soil samples were collected from five experimental sites in the US Midwest representing three soil types. Soil texture and mineralogy were measured using a hydrometer and x‐ray powder diffraction, respectively. The intact cores were scanned with x‐ray computed micro‐tomography to identify visible soil pores, biopores, and particulate organic matter (POM). We specifically focused on pore structure within the detritusphere around the POM of root origin. Results showed that the detritusphere of coarser textured soils, characterized by high sand and quartz contents, had lower porosity in the vicinity of POM compared with finer textured soils. POM vicinities in finer textured soils had high proportions of large (&gt; 300 μm diameter) pores, and their pores were better connected than in the coarser soils. Lower porosity in the outer (&gt; 1 mm) parts of the detritusphere of switchgrass than of prairie suggested soil compaction by roots, with the effect especially pronounced in the coarser soils. The results demonstrated that soil texture and mineralogy played a major, while vegetation played a more modest, role in defining the pore structure in the root detritusphere.

Electrochemical Determination of 2,4-Dichlorophenol in Industrial Wastewater Using Bimetallic Metal-Organic Framework (MOF) Functionalized Graphene Oxide (GO) and Cetyltrimethylammonium Bromide (CTAB)

This study reports a sensor using a bimetallic metal-organic framework combined with 1,3,5-benzenetricarboxylic acid (BTC) (ZrCuBTC MOFs) functionalized graphene oxide (GO) and cetyltrimethylammonium bromide (CTAB) to determine the concentration of 2,4-dichlorophenol (2,4-DCP) in industrial wastewater. ZrCuBTC/GO was cast on a bare glassy carbon electrode followed by CTAB for analyte adsorption to produce the CTAB/ZrCuBTC/GO@GCE. The ZrCuBTC/GO was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), and N2 adsorption–desorption analysis. The electrochemical properties of these materials and 2,4-DCP on the CTAB/ZrCuBTC/GO were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The ZrCuBTC/GO had particle sizes from 20 to 40 nm, a pore diameter of 2.71 nm, a pore volume of 0.793 cm3 g−1, and a surface area of 1227 m2 g−1. Under the optimized conditions, the sensor had excellent electrocatalytic activity and high selectivity for 2,4-DCP. Linear ranges from 0.01 to 0.1, 0.1 to 1.5, and 1.5 to 30 µM were obtained with a low detection limit of 8 nM and excellent reproducibility of 2.71%. Wastewater before and after spiking was analyzed using the sensor and high-performance liquid chromatography (HPLC). The results were comparable with recoveries from 94.9 to 110.3 and 88.6 to 100.2%, respectively. Therefore the developed approach was suitable for the determination of 2,4-DCP in environmental samples.

A novel approach to assess internal pore structure and quantify tortuosity of clogged pervious concrete through image analysis techniques

ABSTRACT The major objective of this research was to develop an innovative approach to characterise the pore structure of pervious concrete (PC) mixtures and quantify tortuosity in pre- and post-clogged conditions through 2D and 3D image analysis. Four different types of PC mixtures were prepared and subjected to computed tomography (CT) scanning to retrieve morphological information covering over 1900 images, followed by tortuosity quantification of each of 200 interconnected pore paths using vascular modelling toolkit (VMTK). The porosity of PC obtained from laboratory-based tests was 10–25% lower than image analyses. Further, along the depth of PC, a significant decrease in the number of pores in the top 60–80 mm was observed due to clogging, which revealed that maintenance be adopted only in the top 80 mm. Control and clogged PC with smaller sized aggregates and lower w/c ratio were more tortuous compared to higher w/c ratio while opposite for larger sized aggregates, ascribed to the occurrence of shorter interconnected pore paths comprising larger pore diameter, remarking that permeability will depend on both tortuosity and path diameter. CT scanning was used in predicting tortuosity and pore interconnectivity of PC through VMTK approach extensively used in medical science and seldom used in engineering.

Effect of Cr content on the high temperature oxidation behavior of FeCoNiMnCrx porous high-entropy alloys

FeCoNiMnCr porous high-entropy alloys were prepared using the activation reaction sintering method with Fe, Co, Ni, Mn, and Cr as raw materials. The oxidation behaviors of FeCoNiMnCrx porous high-entropy alloys with different Cr contents, such as pore structure, the surface oxide film phase composition, structure, and morphology, were characterized by X-ray diffraction (XRD), electron probe micro analysis (EPMA), energy dispersive X-ray spectroscopy (EDS), and pore tester after high-temperature oxidation at 800–1000 °C. The results indicate that the initial porous high-entropy alloy comprises a single FCC solid solution phase. With the increase in Cr content, the average pore diameter, average porosity, and air permeability of the porous high-entropy alloy also increase. The oxidation kinetics of the porous high-entropy alloy after exposure to temperatures between 800 °C and 1000 °C follows a single-stage parabolic evolution law. At the same oxidation temperature, With the increase of Cr content, the oxidation gains gradually increased, at the same Cr content at different temperatures, the antioxidant performance of 1000 °C was the weakest, followed by 800 °C, and 900 °C showed excellent antioxidant performance. The oxidation products are mainly Mn2O3, Mn3O4, (Mn, Cr)3O4, Cr2O3and Fe2O3.

7793 Bone Mineral Density, Turnover And Bone Microarchitecture Alterations With Dapagliflozin In Post-menopausal Women With Type 2 Diabetes Mellitus: An Open-Label, Parallel-Arm, Randomized, Controlled Study

Abstract Disclosure: S.K. Bhadada: None. L. Das: None. M. Baruah: None. V. Singla: None. V. Dhiman: None. S. Ram: None. S. Sharma: None. N. Sachdeva: None. P. Dutta: None. Introduction: Evidence is limited and there is no consensus about the effects of SGLT2i on bone metabolism. The objective of the current study was to assess changes in bone mineral density (BMD), turnover markers (BTMs), and microarchitecture with the use of dapagliflozin in type 2 diabetes mellitus (T2DM). Methods: Post-menopausal women (&amp;lt;65 years) with T2DM (both menopause and T2DM duration &amp;gt; 5 years and HbA1c 7-11%) were randomly allocated (1:1) to receive either add-on dapagliflozin with standard-of-care or standard-of-care alone for T2DM management. Those with osteoporosis, on anti—osteoporotic medication, chronic glucocorticoids (&amp;gt;3 months), thiazolidinediones, phenytoin, tamoxifen, estrogen, eGFR&amp;lt;30ml/min/1.73m2, contraindication/past usage of SGLT2i, or with known endocrinopathy were excluded. Patients were made Vitamin D sufficient [25(OH)D &amp;gt; 30ng/ml] with oral cholecalciferol (60K daily for 1 week), if deficient. BMD (DXA, Hologic), BTMs (P1NP, CTX) and microarchitecture were assessed at baseline, 6 and 12 months. Results: A total of 131 patients were screened, of which 101 were randomized (50 dapagliflozin, 51 non-dapagliflozin). The mean age (± SD) in the dapagliflozin group was 58.1 ± 5.8 years, diabetes duration was 9.4 ± 5.2 years and HbA1c was 8.5 ± 1.7%. Baseline clinico-biochemical, areal BMD, volumetric BMD, trabecular structural (number, thickness, separation) and cortical structural (thickness and porosity) parameters were comparable between both groups. Only cortical pore diameter (Ct.Po.Dm) (±SD) at radius (0.199 ± 0.04 vs 0.180 ± 0.03, p =0.01) and tibia (0.256 ± 0.04 vs 0.226 ± 0.03, p =0.001) were higher in the dapagliflozin than the non-dapagliflozin group. At 6 months, BMD at lumbar spine (LS), hip, femoral neck (FN), and distal radius and BTMs were comparable between the dapagliflozin (n=38) and the non-dapagliflozin (n=39) groups. However, there was significantly higher trabecular thickness (Tb.Th) (0.230 ± 0.02 vs 0.218 ± 0.01, p=0.003), cortical thickness (Co.Th) (1.104 ± 0.2 vs 0.998 ± 0.2, p=0.04), intra-cortical porosity (Ct.Po) (0.008 ± 0.005 vs 0.005 ± 0.003, p= 0.020) and Ct.Po.Dm (0.192 ± 0.03 vs 0.169 ± 0.02, p=0.003), all at radius in the dapagliflozin group. At 12 months follow-up, BMD (g/cm2) at all 4 sites were again comparable between the dapagliflozin (n=36) and non-dapagliflozin (n=36) groups. Serum CTX (pg/ml) (388.8 ± 191.5 vs 327.4 ± 140.8, p = 0.06), and P1NP (ng/ml) (38.8 ± 16.3 vs 32.5 ± 16.3, p = 0.12) were non-significantly higher with dapagliflozin use. Among microarchitecture parameters, only Ct.Po.Dm at the radius (0.189 ± 0.03 vs 0.169 ± 0.03, p= 0.025) and tibia (0.251 ± 0.05 vs 0.228 ± 0.03, p= 0.030) remained significantly higher in the dapagliflozin group. Conclusion: Dapagliflozin has no long-term detrimental effects on BMD, BTMs or bone microarchitecture after 1 year of treatment in postmenopausal women with T2DM. Presentation: 6/1/2024

AI-based modeling studies for dye removal using mixed biomass composites from algae and plant seeds: Isotherm, kinetics, and mechanistic insights

Biomass based remediation have emerged as a promising solution for the economic and sustainable pollutant removal from environment. In this study, novel mixed biomass derived from algae and manila tamarind seeds was synthesized and extensively characterized for application in dye adsorption. Mesoporous structure with pore diameter of 4.006 nm was observed from Brunauer-Emmett-Teller (BET) characterization. Best fit for isotherm was identified with Langmuir model indicating the monolayer nature of dye removal. Artificial intelligence (AI) based models – artificial neural network (ANN) and adaptive neuro fuzzy interference (ANFIS) system were employed for the prediction of dye removal under different conditions, a unique approach which has not been explored in previous studies based on mixed biomass adsorption. In addition, embedding particle swarm optimization (PSO) had a significant improvement in prediction of dye removal. For both Eriochrome black (EB) dye and Brilliant Orange (BO) dye adsorption employing mixed biomass, the ANN-PSO model yielded the best correlation of 0.9999 and 0.9994. For eriochrome black and brilliant orange dye, the maximum adsorption of 79.95 mg/g and 102.4 mg/g for the mixed biomass composite was noted, highlighting the adsorption efficiency of biomass. The uniqueness of the study lies in the integration of mixed biomass adsorption with AI driven modeling, providing a dual approach to enhance dye removal and adsorption efficiency. In addition, the regenerated mixed biomass can be reused for five consecutive cycles, highlighting its practical application, distinguishing from existing research that focused on single use biomass systems.

Glucose Oxidation Performance of Zinc Nano-Hexagons Decorated on TiO2 Nanotube Arrays

Electrochemically anodized TiO2 nanotube arrays (NTAs) were used as a support material for the electrodeposition of zinc nanoparticles. The morphology, composition, and crystallinity of the materials were examined using scanning electron microscopy (SEM). Electrochemical impedance spectroscopy (EIS) was performed to evaluate the electrochemical properties of TiO2 NTAs. Annealing post-anodization was shown to be effective in lowering the impedance of the TiO2 NTAs (measured at 1 kHz frequency). Zinc nanohexagons (NHexs) with a mean diameter of ~300 nm and thickness of 10–20 nm were decorated on the surface of TiO2 NTAs (with a pore diameter of ~80 nm and tube length of ~5 µm) via an electrodeposition process using a zinc-containing deep eutectic solvent. EIS and CV tests were performed to evaluate the functionality of zinc-decorated TiO2 NTAs (Zn/TiO2 NTAs) for glucose oxidation applications. The Zn/TiO2 NTA electrocatalysts obtained at 40 °C demonstrated enhanced glucose sensitivity (160.8 μA mM−1 cm−2 and 4.38 μA mM−1 cm−2) over zinc-based electrocatalysts reported previously. The Zn/TiO2 NTA electrocatalysts developed in this work could be considered as a promising biocompatible electrocatalyst material for in vivo glucose oxidation applications.

Double-stranded vinyl polymer with transformable side chains synthesized in a metal‒organic framework

AbstractPost-polymerization modification (PPM) via active ester chemistry is a valuable method for modulating side-chain structures without altering their main-chain topology. Herein, we synthesized a double-stranded vinyl polymer with an active ester by crosslinking radical polymerization within the nanochannels of a metal‒organic framework (MOF) with a pore diameter comparable to that of the duplex. The resulting double-stranded poly(1,1,1,3,3,3-hexafluoroisopropyl acrylate) (DPHFIPA) was readily converted into acrylates and acrylamides with side chains derived from the nucleophile used in the PPM. This approach offers a pathway for creating double-stranded vinyl polymers with repeating units that are otherwise difficult to synthesize, even when MOF-templated polymerization is used.

Mesoporous Silica Administration as a New Strategy in the Management of Warfarin Toxicity; In Vitro and In Vivo Study

Purpose: Warfarin is one of the most widely used anticoagulants that function by inhibiting vitamin K epoxide reductase. Warfarin overdose, whether intentional or unintentional, can cause life-threatening bleeding. Here, we present a novel warfarin adsorbent based on mesoporous silica that can act as an antidote to warfarin toxicity. Method: Amino-functionalized mesoporous silica (MS-NH2) was synthesized based on co-condensation method through a soft template technique followed by template removal. The prepared structure and functional group were studied by FT-IR, XRD. The morphology was checked by SEM and TEM. The capacity of MS-NH2 in the adsorption of warfarin was evaluated in vitro, at pH=7.4 and pH=1.2. In vivo evaluation was performed in control and warfarin-overdosed animal models. Overdosed animals were treated with MS-NH2 by oral gavage. Biomarkers of organ injury were assessed in animal serum. Results: The MS-NH2 were relatively uniform, spherical with defined diameters (400 nm) and homogeneous structure. synthesized particles had a large surface area (1015 m2 g-1) and mean pore diameter 2.4 nm which leaded considerable adsorption capacity for warfarin 1666 mg/g. In vivo studies revealed that oral administration of MS-NH2 in mice poisoned with warfarin caused a significant difference (p &lt; 0.05) on International Normalized Ratio (INR) and prothrombin time (PT). Moreover, the warfarin with MS-NH2 group demonstrated a notable decrease in biomarkers associated with tissue damage, such as bilirubin, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Conclusion: The results confirm that MS-NH2 administration can be an effective treatment for warfarin toxicity and could potentially mitigate the adverse effects of warfarin poisoning.

Salt weathering resilience in masonry: An accelerated laboratory study involving wind-induced variations

Salt weathering resistance is a critical parameter governing the durability of coastal masonry units and mortars. Accelerated weathering cycles are employed at the laboratory to investigate the responses of substrates and mortars upon exposure to salt, moisture, temperature fluctuations and humidity. In this paper, the individual and synergistic performances of bricks and mortar formulations when exposed to accelerated salt weathering cycles are investigated, incorporating the influence of wind on their resilience. The study examines the behaviour of brick-mortar sandwich specimens and separate specimens of bricks and mortar mixtures comprising cement, dry hydrated lime, fly ash, and limestone. These specimens are exposed to repeated weathering cycles in a 5 % sodium sulphate solution. Along with the mass variations during each weathering cycle, physicomechanical, microstructural, mineralogical and morphological characterization of the specimens are used to compare their salt weathering resistance. The results highlight that the responses of individual masonry components might not collectively translate to the overall performance of the combined system due to hygric resistance, which is minimal when the components have comparable pore size distribution. Higher microporosity (pores of diameter between 0.1 μm and 10 μm) and mechanical strength enough to resist the crystallization stresses together provide better resistance to salt weathering to the individual mortars. However, pore structure compatibility and pore fraction similarity between the components govern the behaviour of the combined system and, therefore, reflect the better performance of sandwich specimens with brick and lime mortars. The study demonstrated that wind accelerates material degradation during salt weathering through progressive erosion, accelerated evaporation and subsequent formation of isolated thenardite.

Sonication-assisted Activation of Empty Fruit Bunches to Produce Activated Carbon for Supercapacitor’s Electrodes: Surface Chemistry and Morphology Characterization.

Thermochemical treatment of empty fruit bunches (EFBs) had been proven to be the fastest way of converting this agro-industrial waste into value. Two-step carbonization and activation was used to convert the EFB to activated carbon with high specific surface area (SSA) and porosity. Hydrothermal carbonization was done at 225 to 275 ; at retention time of 1 to 3 h. Activation was done at 800 for 1 h, using KOH at two different concentrations. The BET surface area, porosity and surface functional groups of the activated carbon were investigated. The samples experienced change in colourations, with the degree of colouration increases with the time and temperature of the reaction. The increase in these parameters also led to increase in the alkane functional groups and corresponding decreased in the hydroxyl functional groups. The specific surface area was measured using BET and maximum surface of 1375.26 m2/g was obtained when the biomass was carbonized at 275 for 1 h, and activated at 800 using KOH at a concentration of 1:1 to the hydrochar. Ultrasonic post-treatment of the activated carbon enhanced the BET surface area and pore volume to about 1.13 and 1.16 times, respectively. The corresponding pore diameter and volume at this optimum condition were 3.32 nm and 0.73 cm3/g, respectively. The material demonstrated a high specific surface area for electronic and ionic diffusions.

A comparison of wire-feed additive manufacturing and hybrid additive/subtractive manufacturing of high nitrogen steel

High nitrogen austenitic stainless steel, referred to as high nitrogen steel (HNS), has been widely studied and applied because of its excellent properties such as high strength, good plasticity and toughness. However, its high nitrogen content makes the deposition metal face problems such as nitrogen porosity, nitrogen escape and loss when it is processed by additive manufacturing (AM), which has a negative impact on the mechanical properties. Two thin-walled specimens without obvious defects were obtained by wire-feed AM and hybrid additive/subtractive manufacturing (HASM) using the self-made HNS wire with 0.7 wt.% N, respectively. The porosity, microstructures and tensile properties of thin-walled specimens were compared. The porosity of the two specimens was tested by an industrial computed tomography (CT) system. The defect volume ratio and the diameter of the largest pore of HASM specimen were reduced about 54% and by 46.6% than those of wire-feed AM, respectively. The morphology of ferrite at different height of both specimens was different including skeletal, lathy and granular. The tensile strength of HASM specimen was better than that of wire-feed AM, which is mainly attributed to the decrease of porosity and grain size.

Effect of pyrolysis parameters on the biochar reactivity in the N-absorption reaction of chemical looping ammonia generation

Biochar from slow pyrolysis was applied to Chemical Looping Ammonia Generation (CLAG) to avoid the preparation of ammonia from fossil fuels and relatively expensive H2. The effects of pyrolysis atmosphere, temperature, heating rate, and residence time on the biochar reactivity in the N-adsorption reaction were investigated. The relationship between specific surface area, average pore diameter, micropore percentage, and disorder degree of biochar on reactivity was evaluated by simple and multiple linear regression and Analysis of Variance (ANOVA). The results showed that the biochar prepared in a CO2 atmosphere with a pyrolysis temperature of 700 °C, a heating rate of 10 °C/min, and a resident time of 30 min had the highest conversion rate of 57.79 % in the N-absorption reaction. When the pyrolysis temperature was increased from 600 °C to 700 °C, the biochar conversion in the N-adsorption reaction was significantly increased due to the Boudouard reaction during biomass pyrolysis. The linear regression and ANOVA results show that the micropore percentage and disorder degree of biochar significantly positively affected the reactivity, guiding feedstock selection and optimization of the preparation method of the carbon source used for CLAG.

A facile and green synthesis of corn cob-based graphene oxide and its modification with corn cob-K2CO3 for efficient removal of methylene blue dye: Adsorption mechanism, isotherm, and kinetic studies

In recent years, the treatment of synthetic dyes has become an environmental concern. In this study, a single step calcination process was used to develop the inventive, simple, and inexpensive adsorbent CC-GO/CC-K2CO3 composite. The composite was employed for the treatment of methylene blue (MB), a cationic dye. Several characterization methods including powder XRD, FTIR, XPS, BET, FESEM, EDX, Raman, and HRTEM techniques were utilized for the analysis of the composite. The surface area and mean pore diameter of CC-GO/CC-K2CO3 were 32.651 m2 g-1 and 3.71 nm, respectively. The adsorption experiment showed that optimal parameters for the removal of MB dye are at an adsorbent dose of 60 mg, initial dye concentration of 80 mg/L, contact time of 150 min, and pH value of 12 at room temperature. Under optimized conditions, CC-GO evidences a removal efficiency of 70.34 ± 1.36 % while after incorporation with CC-K2CO3 the removal capacity sharply increases up to 98.10 ± 0.4 %. Kinetic and isotherm models were used to analyze the removal rate constant and equilibrium adsorption capacity under various adsorption environments. The adsorption study was found to follow the models of pseudo-second order kinetic and Freundlich isotherm. The CC-GO/CC-K2CO3 composite has the maximum adsorption capacity (MAC) of 160.77 mg/g established by the Langmuir isotherm. The prepared composite has demonstrated the capacity to be recycled up to three times with a gradual decrease in its adsorption behavior, exhibiting removal efficiency of 61.66 ± 2.04 %.A cost estimation study of the composite was also performed to assess its cost effectiveness.

Enhanced tetracycline degradation using UV/Fenton/titanium dioxide (TiO2) hybrid process

TiO2 was synthesized using neem leaf extract as soft bio template and Titanium (IV) isopropoxide (C12H28O4Ti) as a precursor. Morphological properties revealed well crystalline anatase phase of 19.8 nm size for the biotemplated TiO2 (B-TiO2) compared to 24.2 nm of the non-templated TiO2 (N-TiO2). TEM revealed a nano sheet-like structure for the B-TiO2 and it exhibited a larger SBET surface area (35.45 m2/g) and average pore diameter (5.74 nm) compared to the N-TiO2 (19.72 m2/g) and (2.028 nm) respectively. XPS results showed carbon peaks indicating small bio-carbon doping on the lattice of the TiO2, which can promote charge transfer upon light excitation during photocatalyst reactions. The results of the photoluminescence study indicate reduced PL intensity of the B-TiO2 which signifies the suppression of recombination of charge carriers or electron-hole pairs in the B-TiO2. The photocatalytic activity was assessed by the photodegradation of tetracycline (TC: 50 mg/L) under UV irradiation and the B-TiO2 was employed as a photocatalyst. In the absence of UV light, B-TiO2 catalyst slightly removed TC due to limited active species. However, the degradation of TC increases significantly due to the synergetic effect of the UV/Fenton/B-TiO2 hybrid system. Moreover, the biotemplate exposes the surface of the B-TiO2 which permits improved utilization of all surface-active sites. Quenching experiments were also performed via scavengers, results confirmed that hydroxyl radicals, superoxide radicals and electrons are the key reactive species in the TC degradation. The effects of influential parameters such as B-TiO2 dosage, TC concentration, pH, and Fe2+ to H2O2 molar ratio were also investigated, in addition, the catalyst is stable, as it achieved > 80 % TC degradation efficiency after five reuse cycles.

Ionic selectivity of nanopores: Comparison among cases under the hydrostatic pressure, electric field, and concentration gradient

The ionic selectivity of nanopores is crucial for the energy conversion based on nanoporous membranes. It can be significantly affected by various parameters of nanopores and the applied fields driving ions through porous membranes. Here, with finite element simulations, the selective transport of ions through nanopores is systematically investigated under three common fields, i.e. the electric field (V), hydrostatic pressure (p), and concentration gradient (c). For negatively charged nanopores, through the quantitative comparison of the cation selectivity (t+) under the three fields, the cation selectivity of nanopores follows the order of t+V > t+c > t+p. This is due to the transport characteristics of cations and anions through the nanopores. Because of the strong transport of counterions in electric double layers under electric fields and concentration gradients, the nanopore exhibits a relatively higher selectivity to counterions. We also explored the modulation of t+ on the properties of nanopores and solutions. Under all three fields, t+ is directly proportional to the pore length and surface charge density, and inversely correlated to the pore diameter and salt concentration. Under both the electric field and hydrostatic pressure, t+ has almost no dependence on the applied field strength or ion species, which can affect t+ in the case of the concentration gradient. Our results provide detailed insights into the comparison and regulation of ionic selectivity of nanopores under three fields which can be useful for the design of high-performance devices for energy conversion based on nanoporous membranes.