Activation Energy Of Adsorption Research Articles

A novel model of kinetics and thermodynamics for shale gas adsorption–diffusion

The study of adsorption–diffusion kinetics in shale gas reservoirs is crucial for predicting reserves and assessing production. Although some scholars have proposed adsorption–diffusion kinetics models, there are few models and interpretation methods that systematically consider Arrhenius’s thermodynamics parameters and actual adsorption gas concentration. In this study, we propose a novel model for analyzing the kinetics processes of adsorbed gas and free gas in shale. The analysis of adsorbed gas kinetics experimental data indicates a negative correlation between temperature and the adsorption–diffusion equilibrium time. Sensitivity analysis of the parameters reveals that three parameters (the diffusion activation energy, adsorption activation energy, and desorption pre-exponential factor) are positively correlated with adsorption–diffusion equilibrium time, whereas the other three parameters (the diffusion pre-exponential factor, adsorption pre-exponential factor, and desorption activation energy) are negatively correlated. Furthermore, we find that higher temperatures lead to lower concentrations of free gas at equilibrium state. Larger radius positions in spherical particles tend to reach adsorption–diffusion equilibrium earlier. Compared to the traditional diffusion kinetics model, the proposed novel model exhibits a significant lag effect in the calculated equilibrium time and more accurately describes the gas adsorption-diffusion kinetics equilibrium process.

A Hollow Hemispherical Mixed Matrix Lithium Adsorbent with High Interfacial Interaction for Lithium Recovery from Brine

Mixed matrix lithium adsorbents have attracted much interest for lithium recovery from brine. However, the absence of an interfacial interaction between the inorganic lithium-ion sieves (LISs) and the organic polymer matrix resulted in the poor structural stability and attenuated lithium adsorption efficiency. Here, a novel hollow hemispherical mixed matrix lithium adsorbent (H-LIS) with high interfacial compatibility was constructed based on mussel-bioinspired surface chemistry using a solvent evaporation induced phase transition method. The effects of types of functional modifiers, LIS loading amount, adsorption temperature and pH on their structural stability and lithium adsorption performance were systematically investigated. The optimized H-LIS adsorbent with the LIS loading amount of 50 wt.% possessed the structural merit that the LIS functionally modified by dopamine exposed on both the inner and outer surfaces of the hollow hemispheres. At the best adsorption pH of 12.0, it showed a comparable lithium adsorption capacity of 25.68 mg·g−1 to the powdery LIS within 4 h, favorable adsorption selectivity of Mg/Li and good reusability that could maintain over 90% of lithium adsorption capacity after the LiCl adsorption—0.25 M HCl pickling-DI water cleaning cycling processes for three times. The interfacial interaction mechanism of H-LIS for lithium adsorption was innovatively explored via advanced microcalorimetry technology. It suggested the nature of the Li+ adsorption process was exothermic and dopamine modification could reduce the activation energy for lithium adsorption from 15.68 kJ·mol−1 to 13.83 kJ·mol−1 and trigger a faster response to Li+ by strengthening the Li+-H+ exchange rate, which established the thermodynamic relationship between the structure and Li+ adsorption performance of H-LIS. This work will provide a technical support for the structural regulation of functional materials for lithium extraction from brine.

Unveiling the water sorption kinetics, thermodynamics, and air dehumidification performance of sustainably synthesized metal–organic frameworks

This study focuses on the feasibility of sustainably synthesized MIL-100(Fe) as an alternative to conventional desiccants, such as silica gel and zeolites, which have low adsorption capacity and poor thermal characteristics for air dehumidification. MIL-100(Fe), a metal–organic framework, shows promise due to its excellent adsorption and customizable thermal properties. However, its synthesis typically involves toxic materials and high temperature/pressure conditions, which restrict its bulk production for large-scale applications. This study aims to explore sustainable synthesis methods for MIL-100(Fe) using non-toxic materials and milder reaction conditions and investigate its material characteristics and dehumidification performance. Experimental analyses are carried out to measure adsorption isotherms, kinetics, sorption heat, activation energy, and cyclic stability, and numerical simulations are conducted in COMSOL Multiphysics platform to estimate dehumidification performance. The test results demonstrate that MIL-100(Fe) has a higher water adsorption capacity compared to silica gel, with a unique stepwise adsorption into its two types of mesoporous cages. Increased temperatures cause the adsorption and desorption isotherms to shift towards higher relative humidity levels. The heat of water adsorption and desorption ranges between 2630–2906 kJ/kg and 2763–2848 kJ/kg, respectively. MIL-100(Fe) demonstrates high stability and no significant loss in water uptake capacity. The simulated performance indicate that MIL–100(Fe) has superior reaction rates and is 82 % more effective than the silica gel rotary wheel dehumidifiers.

Gold recovery from chloride leach solution of TCCA using D301 anion exchange resin and elution with thiourea

Trichloroisocyanuric acid (TCCA), which is used for gold leaching, is an alternative to cyanidation due to its lower toxicity and higher efficiency. This study investigated the gold recovery procedures from highly effective chloride leaching solution using the D301 resin. This approach prevented the inhibition of gold adsorption when using activated carbon. Herein, the optimal conditions for gold adsorption were discussed, including establishing adsorption kinetics and isotherms, and calculating adsorption activation energy. Additionally, SEM (Scanning Electron Microscope), FTIR (Fourier Transform Infrared Spectroscopy), and XPS (X-ray Photoelectron Spectroscopy) techniques were used to reveal the mechanism of gold adsorption using D301 resin. Under optimal conditions (pH 4.0, temperature 25 °C, time 120 min), an average adsorption percentage of 99.2% was achieved. Analysis of the adsorption data confirmed that gold adsorption followed the pseudo-second-order kinetic model and Freundlich adsorption isotherm. The calculated activation energy was 9.69 kJ mol−1, indicating a predominance of physical adsorption involving ion exchange reactions with protonated tertiary amine groups in the D301 resin beads. Furthermore, among various eluents tested in desorption experiments, a solution containing a mixture of thiourea and hydrochloric acid with 0.4 mol L−1 and 0.8 mol L−1, respectively, demonstrated superior efficiency, achieving a successful desorption percentage reaching 95.7 ± 0.3% within 80 min. After three cycles of resin regeneration, the regeneration efficiency reached 91.2% while maintaining an average adsorption percentage of 95.3%.

Anticorrosive activity of Melothria perpusilla: A renewable and sustainable inhibitor

Anticorrosive activity of Melothria perpusilla extract on mild steel in H2SO4 was examined by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy methods. The results revealed that mild steel corrosion was effectively controlled by the extract with 99.4 % efficiency at 3000mg/L concentration. The efficiency was improved with higher extract concentration but decreased as the temperature increased. The Tafel plots and its corrosion potential value (<85 mV) inferred that Melothria perpusilla acts as a mixed type inhibitor. Adsorption of phytochemicals onto the surface of mild steel is the primary factor in reducing corrosion. The increase in activation energy for adsorption from 22.73 kJ mol−1 in acid to 133.74 kJ mol−1 in extract's presence confirms the active role of phytochemicals in adsorption process. The increase in charge transfer resistance from 3.21 Ω cm2 in acid to 369.2 Ω cm2 in extract's presence, coupled with a decrease in double layer capacitance in the EIS investigation, suggests that a charge transfer mechanism is active at the mild steel-solution interface. Gas chromatography-Mass spectroscopy revealed the presence of five major phytochemicals along with other organic compounds in the extract. Fourier transform infrared and UV–visible spectroscopies indicated the active functional moieties (-COOH, –CONH2, -C-O-C-, –C=C- and long chain alkyl groups) are involved in the inhibition. Scanning electron microscopy confirmed the existence of shielding film of phytochemicals on mild steel. Density functional theory validated the inhibitory properties of the constituents. Therefore, it is concluded that Melothria perpusilla is an efficient green inhibitor in acidic condition.

Synthesis of CoFe2O4/TiO2/PANI Nanocomposite Photocatalyst, and Examination of Its Decolorization Efficiency on Rhodamine B

AbstractThis study aims to reduce the band gap by doping wide band‐gap TiO2 with CoFe2O4 and PANI to improve the photocatalytic efficiency and examine the decolorization kinetic of Rhodamine B (RhB). The characteristics of the nanocomposites were thoroughly assessed through the utilization of SEM‐EDS, TEM, XRD, FTIR, VSM, UV‐Vis, PL, and XPS analyses. The SEM and TEM analyses revealed that CoFe2O4/TiO2/PANI has a homogeneously porous structure. XRD analysis results were found to show good agreement with the standard diffraction data cards. The band structures obtained by FTIR analyses were compatible with literature studies. The band gap energies determined by UV‐Vis analyses were determined as 2.86 eV for CoFe2O4/TiO2/PANI. The decrease of CoFe2O4/TiO2/PANI recombination rate was proven with PL results. The different initial dye concentrations, temperature, and light intensity parameters were used to determine the decolorization kinetics of RhB over CoFe2O4/TiO2/PANI. The photodegradation rates of RhB in reactions catalyzed by PANI, CoFe2O4, commercial‐TiO2, CoFe2O4/TiO2, and CoFe2O4/TiO2/PANI were determined as 7.6 %, 20.7 %, 26.6 %, 32.4 %, and 48.8 %, respectively. According to data obtained from the decolorization of RhB on CoFe2O4/TiO2/PANI nanocomposite, the appropriate kinetic model was determined Network kinetic. The adsorption equilibrium constant (KB) and activation energy (Ea) were calculated as 0.007 and 7.9 kJ/mol, respectively.

Amine-functionalized high-surface-area Al2O3 adsorbent for CO2 capture: Effect of the support calcination conditions

Porous alumina has garnered interest as a substrate in the development of solid amine adsorbents for CO2 capture. However, the calcination conditions of alumina can significantly alter its properties, which in turn affects the adsorption performance of the resulting adsorbents. In this study, high-surface-area alumina was synthesized using a reverse microemulsion method. The impact of the calcination conditions on the pore structure and surface properties of the alumina precursor was examined. Additionally, the porous alumina produced under various calcination conditions served as the support for tetraethylenepentamine (TEPA) loading, and the CO2 capture performance of the resultant adsorbents was assessed. The adsorption kinetics and activation energy were analyzed, emphasizing the cyclic stability when regenerated in a realistic CO2 atmosphere. Our findings indicate that alumina calcined under an air atmosphere with a lid exhibited the highest capture capacity (reaching 89.97 mg/g after a 40 wt% TEPA loading), compared to other alumina samples. The adsorption kinetics corresponded closely with the Avrami model, yielding an activation energy (Ea) of 4.75 kJ/mol. Both alumina samples calcined in air, with and without a lid, demonstrated robust cycling stability and resistance to urea formation. The underlying anti-urea mechanisms were also elucidated in the study.

Lignin-impregnated biochar assisted with microwave irradiation for CO2 capture: adsorption performance and mechanism

Bamboo biochar was modified by lignin impregnation and microwave irradiation to enhance its performance for CO2 capture. The pore structure of lignin-impregnated biochar was significantly affected by the impregnation ratio. The maximum specific surface area of 377.32 m2 g−1 and micropore volume of 0.163 cm3 g−1 were observed on the biochar with an impregnation ratio of 1:20 (mass ratio of lignin to biochar). Lignin impregnation increased the CO2 adsorption capacity of biochar up to 134.46 mg g−1. Correlation analysis confirmed the crucial role of biochar’s pore structure in adsorption. The Avrami model fitted the CO2 capture curves well. The calculation of adsorption activation energy suggested that the adsorption process was dominated by physical mechanism assisted with partial chemical mechanism. Meanwhile, Langmuir isotherm analysis indicated that lignin impregnation transformed the larger pores of biochar into more uniform micropores, thereby making the adsorption process closer to monolayer adsorption. Both the high reusability (89.79–99.06%) after 10 successive cycles and the excellent CO2 selectivity in competitive adsorption confirmed that lignin-impregnated biochar is an outstanding adsorbent for CO2 capture.Graphical

Stationary sources exhaust gases sensors application by MoTeSe monolayer doped with ZrO2(1,2) cluster: A DFT study

Based on density functional theory (DFT), the adsorption properties of MoTeSe monolayers doped with ZrO2(1,2) are studied. Firstly, the stability of ZrO2(1,2)-MoTeSe monolayer is proved by the analysis of the optimized structure after doping and the calculation of adsorption energy and activation energy. Then, in order to investigate the adsorption effect of stationary sources exhaust gases (NO, H2S, HCHO) on the doped monolides, the adsorption parameters of the adsorption system such as adsorption energy (Ead), differential charge density (DCD), charge transfer amount (QT), density of states (DOS) and recovery time (τ) were analyzed and calculated. Finally, the energy gap was studied based on the molecular orbital theory to describe the change of material conductivity during the adsorption process. The research showed that the conductivity of H2S adsorbed on the ZrO2-modified MoTeSe monolayer decreased, while the conductivity of other adsorption systems increased. The results show that ZrO2-MoTeSe/NO, ZrO2-MoTeSe/H2S and (ZrO2)2-MoTeSe/H2S have good adsorption effects, and ZrO2(1,2)-MoTeSe provides reliable theoretical support for the application of removing waste gas from fixed pollution sources, which can effectively prevent and control air pollution. It will make positive contributions to protecting the ecological environment and promoting sustainable development.

Thermal atomic layer deposition of aluminum oxide, nitride, and oxynitride: A mechanistic investigation

Atomic layer deposition (ALD) has been proven to be a versatile method for the deposition of thin films of various materials. It yields films with exceptional conformality and allows tunable film compositions with control of film thickness at the atomic level. Thin films of Al oxide, nitride, and oxynitride are deposited via ALD using Al(CH3)3 (TMA)/AlCl3 with H2O/NH3. Herein, surface chemical reactions are examined using density functional theory calculations to elucidate the adsorption, oxidation, and nitridation of precursors [TMA and AlCl3] as well as the mechanism controlling the composition of Al oxynitride thin films obtained through ALD. The hydrogen-terminated substrate surface is transformed into a CH3/Cl-terminated surface after the reaction with the TMA/AlCl3 precursors. The molecular adsorption of TMA occurs through a spontaneous reaction, whereas that of AlCl3 requires a slight energy input. Although the adsorption energy of AlCl3 is higher than that of TMA, the activation energy and energy change of AlCl3 adsorption are higher and lower than those of TMA, respectively; furthermore, the use of AlCl3 results in the generation of a corrosive by-product (HCl). A similar tendency is observed in the second ALD half reaction, which is oxidation. Nitride formation is endothermic for molecularly adsorbed AlCl3 but exothermic for TMA. Furthermore, the investigation of the exchange reactions between surface moieties and excess gaseous reactants reveals a preference for the substitution of N by O, which is attributed to differences in bond energies between the surface moieties and the surface metal atom, as well as between H2O and NH3.

Tetraethylenepentamine-modified Cu2(OH)PO4 for efficient CO2 capture

This study focused on creating tetraethylenepentamine (TEPA) modified copper hydroxyl phosphate (Cu2(OH)PO4) adsorbents via physical impregnation. The TEPA-modified Cu2(OH)PO4 adsorbents were analyzed for structure and characteristics through SEM, XPS, TGA, N2 adsorption–desorption studies. The effects of different parameters (TEPA contents, temperatures, flow rates and CO2 concentrations) and cyclic stability were evaluated. Kinetics, thermodynamics and density functional theory (DFT) calculations were employed to understand the impact of TEPA modification on Cu2(OH)PO4 for CO2 adsorption. Experimental results showed that a 50 wt% loading yielded optimal results, with a maximum surface area of 65.12 m2/g, a pore volume of 0.29 cm3/g, and a maximum adsorption capacity of 6.54 mmol/g. The amine efficiency is extraordinary which reached 67 %. The best performance occurred at 60 °C, 30 ml/min gas flow, and 15 vol% CO2 concentration. The pseudo-second-order kinetic model better described the CO2 adsorption process. The adsorption process was found to be exothermic at 20–60 °C and endothermic at 60–80 °C, suggesting physical–chemical co-adsorption and chemical adsorption, respectively. The adsorption activation energy is 34.322 kJ/mol. The DFT shows the adsorption energy ranged from −0.565 eV to −5.584 eV, indicating coexistence of physical and chemical adsorption. The d-band theoretical calculation shows that TEPA doping is beneficial to the adsorption of CO2 by Cu2(OH)PO4. Minimal structural modification of the adsorbate was observed, with bond lengths changing by less than 1 %. The density of states (DOS) curve shifted toward lower-energy states after adsorption, suggesting a more stable structural configuration post-adsorption. We have proved that TEPA-Cu2(OH)PO4 has good adsorption for CO2 and is an efficient green adsorption material.

Recycling of waste toner derived from exhausted printer cartridges as adsorbent for defluoridation of water

Due to the broad adoption of electronic and electrical equipment and the quick advancement of contemporary innovations in this domain, significant amounts of electronic waste have been produced. This category of waste includes the toner powder used by printers, copiers, and fax machines to print text and images. This paper describes a sustainable and environmentally friendly method of recycling waste toner powder. The chemical composition of this printer cartridge toner (PCt) powder is carbon, Fe3O4, polypropylene (polymeric resin), and SiO2 composite. Toner powder from exhausted printer cartridges was utilized as an adsorbent to remove fluoride from water. It has a fluoride adsorption capacity of 60 mg/g and a specific surface area of 20 m2/g. X-ray diffraction and electron microscopic investigations were used to investigate the chemical composition, structure, and surface morphology of the material. To analyze the collected experimental data, the Freundlich and Langmuir adsorption isotherm models were used. Time-dependent kinetic experiments were conducted to determine the mechanism of the adsorption process using pseudo-first-order kinetics, pseudo-second-order kinetics, and intraparticle diffusion kinetic models. The fluoride adsorption process was shown to be feasible and spontaneous (ΔG < 0) based on calculated thermodynamic characteristics, which included enthalpy, Gibbs free energy, entropy (ΔS > 0), and adsorption activation energy. The study also discussed its reusability as an adsorbent and examined its functioning capability in actual water.

Thermodynamic and Kinetic Equilibrium for Adsorption of Cellulosic Xylose of Commercial Cation-Exchange Resins.

The development of low-cost purification technology is an indispensable need for industrial biorefinery. Xylose is easily obtained from hydrothermal pretreatment of lignocellulosic biomass. This current study emphasizes the chromatographic monosaccharide separation process using commercial cation-exchange resins (CER) including Amberlite 120 and Indion 225 to separate xylose from a mixture of hydrolysates. To understand the performance of the two CER, the studies of equilibrium, thermodynamics, and kinetics were evaluated. In this study, with different xylose concentrations, the adsorption equilibrium was found to follow the Freundlich isotherm model well (R2 > 0.90 for both CER). The results indicated that a pseudo-second-order model represented the xylose adsorption kinetics. In addition, the activation energy of xylose adsorption onto both CER, i.e., Amberlite 120 and Indion 225 was 34.9 and 87.1 kJ/mol, respectively. The present adsorption studies revealed the potential of these commercial CER to be employed as effective adsorbents for monosaccharide separation technology.

Evaluation of the Efficiency of a Chitosan Membrane in Removing Gallic Acid from Wastewater Using Adsorption in Batch Mode and Separation by Dead-End Filtration

Abstract: This study assesses the efficacy of adsorption and separation techniques for removing gallic acid (GA) from wastewater using a chitosan membrane (Chi-1.5%). The effect of GA concentration, mass of adsorbent, contact time and pH were investigated. GA adsorption was best fitted by the Freundlich and Langmuir isotherm models, with a correlation coefficient of 0.9972 and 0.9929, respectively. The maximum adsorption capacity of GA (301.70 mg/g) was calculated at pH 8.4 and 303 K. Gibbs free energy was also calculated. The negative value showed that the GA adsorption is spontaneous. On the other hand, the value of activation energy of adsorption (&lt; 7 kJ/mol) indicates that the adsorption is physical in nature. The adsorption kinetics was best fitted by the pseudo-second-order model, and the effect of pH (8.4 and 7.1) on the adsorption is explained by theoretical calculation of the fraction of ions present in solution and their affinity for the membrane. The maximum percentage of GA removal based on a dead-end filtration system was 18.58% at a GA concentration of 300 ppm, pH 8.4 and a pressure of 1 bar. Volume exclusion was found to have a very slight effect on removing GA from the aqueous phase, while adsorption played the main role in removing GA.

Investigation of CO2 adsorption on nitrogen-doped activated carbon based on porous structure and surface acid-base sites

The purpose of this paper is to reveal the effects of porous structure and surface acid-base sites on CO2 adsorption for those nitrogen-doped activated carbons, which were prepared in a tube furnace with anaerobic conditions (TF) and muffle furnace with oxygen-poor conditions (MF), respectively. Subsequently, the porous structure and surface group distribution of the prepared activated carbons TF and MF were characterized in detail through those methods such as scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), Barret-Joyner-Halenda method (BJH), Horvath-Kawazoe method (HK), Dubinin-Radushkevich method (DR), mercury intrusion porosimetry (MIP), non-local density functional theory method (NLDFT), (in-situ) Fourier transform infrared spectroscopy (FTIR), Raman spectra (RS), X-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD). Then the thermodynamic and kinetic characteristics of CO2 adsorption such as adsorption capacity, selectivity, and activation energy were systematically investigated based on the static volumetric method and dynamic adsorption method. The results showed that the anaerobic or oxygen-poor preparation atmosphere affected the micropore volume and surface functional group distribution of activated carbons. Thus the activated carbon TF exhibited a higher adsorption capacity of CO2 (7.9 mmol g−1, 100 kPa and 273 K) and longer dynamic breakthrough time due to the higher microporosity (Vmic/Vt = 90 %), while the activated carbon MF exhibited the higher selectivity (14.7, CO2/N2 molar ratio of 1:1) and adsorption rate due to the higher nitrogen and oxygen contents (11.23 %, 13.53 %) in the main forms such as pyrrole nitrogen (N-5), carbony, and carboxyl. Overall, CO2 adsorption on the activated carbons was verified to be a dominant physical adsorption and exothermic process, which was suitable to be described by a quasi-first-order dynamic model. Meanwhile, compared with TF, the activated carbon MF exhibited the higher activation energy of CO2 adsorption (12.98 kJ mol−1 for TF and 17.23 kJ mol−1 for MF), accompanied by the larger rate constants (k1) and diffusion coefficients (D). The higher activation energy for MF meant that the adsorption temperature had a stronger effect on the rate constant during CO2 adsorption.

Metal-decorated 3D tin oxide nanotubes in a monolithic sensor array chip for room-temperature gas identification

Inadequate limit of detection at room temperature and unsatisfactory selectivity remain challenge for wide applications of the chemiresistive gas sensors. Nanostructured gas sensors ensure the desirable activation energy for the gas adsorption and chemical reactions, favorable for room-temperature parts-per-billion (ppb) level gas detection. In this work, we demonstrated a single-chip integrated gas sensor array (4 ×4 pixels) based on kinds of metal (Pt, Pd, Au, Ag) decorated 3D SnO2 nanotubes for ultrasensitive room-temperature gas-sensing. The nanostructured sensor array has a high surface area-to-volume ratio, enabling room temperature sensing with high detection response toward H2 (minimum 5 ppm), formaldehyde (minimum 50 ppb), toluene (minimum 50 ppb) and NO2 (minimum 100 ppb) with the detection accuracy within 5% range, respectively. In addition, the effect of metals decoration on the gas identification features were systematically conducted, and these specific response features can be mainly attributed to metal activation capability toward the gases, which enables demonstrating differentiable response patterns for the target gases identification employing a pattern recognition algorithm. These results demonstrate that the proposed strategy helps to provide an excellent route for the future low-power-consumption smart sensing devices design and fabrication.

Atomic ruthenium doping in collaboration with oxygen vacancy engineering boosts the hydrogen evolution reaction by optimizing H absorption

Development of cost effective and performance efficient catalyst for hydrogen evolution reaction (HER) holds great importance to advance a green future. In this work, atomic Ru doped NiMoO4 nanorod arrays with rich oxygen vacancy were tailor-synthesized on nickel foam. Both theoretical calculations and experiments elucidated the synergistic effects of Ru doping and oxygen vacancy engineering for the facilitating of H adsorption and water activation energy barrier reduction for water dissociation, which significantly enhanced the hydrogen evolution kinetics and thereby accelerated the water splitting process. The sample obtained exhibits a remarkably low overpotential of 49 mV at 10 mA cm−2 and a super robust stability, which is comparable to the performance of commercially available Pt/C and among one of the most efficient catalysts towards water splitting. Moreover, an integrated green energy-to-hydrogen device using sunlight, wind and thermal as the power sources was successfully built to prove the promising potential of the developed catalyst for the practical applications. This work provides a feasible strategy to prepare low-cost metal oxide electrocatalysts by noble element doping and oxygen vacancy engineering for efficient hydrogen evolution reaction.

Ultrasound and defect engineering-enhanced nanozyme with high laccase-like activity for oxidation and detection of phenolic compounds and adrenaline

Perusing metal-based redox nanozyme offers new opportunity for pollutant removal and biosensor, but ultrasound (US)-driven laccase-like nanozyme remains a significant challenge, especially in combination with defect engineering strategy. Herein, the Cu2Ov@Ce-TCPP was synthesized by doping Ce3+ on the surface of Cu2O nanocube and then coating with the porphyrin sonosensitizer. The Ce-doped porphyrin metal-structure in nanozyme was demonstrated to generate oxygen vacancy defects, which could obviously promote the laccase-like activity of Cu2Ov@Ce-TCPP nanozyme under US. XPS characterization and density functional theory (DFT) theoretical calculation revealed that the ultrasonic stimulation is beneficial to accelerate the electron transfer rate and O2 adsorption to improve catalytic activity, and Cu2Ov@Ce-TCPP nanozyme exhibits low adsorption energy and activation energy due to the presence of oxygen defect site, resulting in high laccase-like activity. The interaction between Ce atom and porphyrin structure also improved the sonocatalytic ability of the nanozyme. Meanwhile, Cu2Ov@Ce-TCPP nanozyme has been used for detecting and degrading a series of phenolic compounds. The detection adrenaline method has a linear range of 3.3–1000 μM and a detection limit as low as 0.96 μM with good reproducibility. The developed US-enhancing and recyclable laccase-like nanozyme system provides a promising strategy for the oxidation and detection of phenolic compounds.

Preparation and characterization of γ-AlOOH/Fe3O4 for the highly effective removal of Congo red from wastewater

Due to the highly toxic and non-degradable nature of Congo red (CR) in wastewater, how to effectively separate CR from an aqueous solution remains a major challenge in the field of wastewater treatment. Consequently, an γ-AlOOH/Fe3O4 composite was prepared using the sol-gel method under ultrasonic stirring conditions. The structural and surface properties of the magnetic γ-AlOOH/Fe3O4 composite were analyzed in detail using a range of physical and chemical characterization methods. It was shown that the γ-AlOOH/Fe3O4 composite possessed the advantages of its layered structure, high porosity, and positively charged surface, all of which were conducive to improving the adsorption capacity of CR. During our CR adsorption experiments, the maximum adsorption amount reached 1350.11 mg g−1. Simultaneously, the whole adsorption process was more consistent with the pseudo-second order kinetic and Langmuir isotherm model. The adsorption activation energy and thermodynamic data prove that the adsorption process was chemisorption, spontaneous, and endothermic. In addition, the γ-AlOOH/Fe3O4 composite can be easily separated from treated-wastewater upon the application of an external magnetic field and its excellent reproducibility increases its practical application value. Therefore, the γ-AlOOH/Fe3O4 composite synthesized in this study has a wide range of practical applications.

Amine-functionalized disordered hierarchical porous silica derived from blast furnace slag with high adsorption capability and cyclic stability for CO2 adsorption

This study proposes a novel solution to the challenge of achieving high cycle stability in CO2 adsorbents prepared through impregnation with organic amines. Specifically, industrial waste blast furnace slag was used to prepare a support material called BHF, which possesses three pore structures: micropores, mesopores, and macropores. This unique structure facilitates high loading of organic amines and improves CO2 adsorption effectiveness. To counteract agglomeration effects caused by loading large amounts of organic amines, the morphology and skeleton of the carrier material were analyzed in detail. The results showed that the rough “hive” morphology, disordered cell-like skeleton structure and abundant pores of BHF allows for uniform dispersion of polyethyleneimine (PEHA), an organic amine, and provides advantageous transportation of CO2 molecules within the adsorbent. Based on the study of kinetics, activation energy, and isosteric heat of adsorption, the adsorption mechanism of 70PEHA-BHF was determined to be a chemical-physical binding adsorption. The adsorption-diffusion mechanism suggests that the rate-limiting step is film diffusion. Furthermore, the 70PEHA-BHF adsorbent achieves a balance between CO2 adsorption capacity and cycle stability. At 80 °C and 15 vol.% CO2, the CO2 adsorption capacity of 70PEHA-BHF is 6.27 mmol/g, with only a 1.43 % CO2 loss after 10 cycles of testing. It anticipates that this newly developed 70PEHA-BHF adsorbent will provide additional possibilities for the application of hierarchical porous materials in CO2 adsorption research.