Initial Sorption Research Articles

Effects of Humidity on Mycelium-Based Leather.

Leather is a product that has been used for millennia. While it is a natural material, its production raises serious environmental and ethical concerns. To mitigate those, the engineering of sustainable biobased leather substitutes has become a trend over the past few years. Among the biobased materials, mycelium, the fungal "root" of a mushroom, is one of the promising alternatives to animal leather, as a material with tunable physicomechanical properties. Understanding the effect of humidity on mycelium-based leather material properties is essential to the production of durable, competitive, and sustainable leather products. To this end, we measured the water sorption isotherms on several samples of mycelium-based leather materials and investigated the effects of water sorption on their elastic properties. The ultrasonic pulse transmission method was used to measure the wave speed through the materials while measuring their sorption isotherms at different humidity levels. Additionally, the material's properties were mechanically tested by performing uniaxial tensile tests under ambient and immersed conditions. An overall reduction in elastic moduli was observed during both absorption and immersion. The changes in the measured longitudinal modulus during water sorption reveal changes in the elasticity of the test materials. The observed irreversible variation of the longitudinal modulus during the initial water sorption can be related to the material production process and the presence of various additives that affect the mechanical properties of the leather materials. Our results presented here should be of interest to material science experts developing a new generation of sustainable leather products.

Study of the Ion-Exchange Capacity of Clinoptilolite for Copper Ions under Ideal Displacement Conditions in the Dynamic Mode

The ionic mechanism of copper ion sorption from an aqueous medium has been confirmed. The study has elucidated the regularities of the process within a stirred bed reactor, where kinetics are limited by the internal diffusion region. Initial sorption curves under dynamic conditions have been obtained.

Sorption and desorption behavior and mechanism of oxytetracycline on soil aggregates organic matter separated from soils and sediments in the Yellow River Delta

Soil aggregates organic matter (SAOM) is composed of free particulate organic matter (fPOM), intra-aggregate particulate organic matter (iPOM), and mineral-associated organic matter (mSOM), which are major antibiotic sorbents that play a significant role in the soil organic matter (SOM) turnover process. To date, the oxytetracycline (OTC) sorption and desorption behavior and mechanisms on SAOM have not been contrastively analyzed. SAOM organic components have been used to study scientific problems and to determine their influence on the fate and migration of OTC among the SOM turnover process. Results demonstrated that SAOM had great OTC sorption capacity ranging from approximately 12100–513,000 mg kg−1 and the desorption proportion was no more than 33.60%. The slow organic carbon pool (mSOM) had greater OTC accumulation capacity than the intermediate active pool (iPOM) and the active pool (fPOM), while OTC was more likely to reside in the active pool in wetlands (fPOM-w) and oil waste land (fPOM-o) than the organic carbon pool (mSOM-f) in farmland with human activity interference. The hysteresis was affected by SAOM's physical surface characteristics when the OTC initial equilibrium sorption concentration was higher than 200 mg L−1. When it was lower than that, it was affected by the organic carbon composition. Hydrogen bonds, electrostatic interactions, and π-π interactions dominated the SAOM-OTC interactions. The results of this study will be useful for evaluating the long-term behavior and migration of antibiotics in SOM turnover processes and could refine risk assessments of antibiotics contamination in soil environmental systems.

Adsorption kinetics of organic phosphates on goethite and aluminium oxide: The equation used to describe the reaction

AbstractAdsorption kinetics of three organic phosphate compounds (OPs) with varying molecular sizes and structures and inorganic phosphate (Pi) were investigated on α‐Al2O3 and poorly crystalline goethite. The organic phosphates were inositol hexaphosphate (IHP), glycerol phosphate (GlyP) and glucose‐6‐phosphate (G6P), and the inorganic phosphate was KH2PO4. Batch adsorption experiments were performed at 25°C. We tested the sorption kinetic data using various non‐linear models/equations and on their transformed linear forms by applying appropriate statistics. Besides, we also used a modified non‐linear equation having four parameters to this effect. Data were found to fit best with the modified equation and described the whole sorption process satisfactorily. For sorption of compounds on to the surface of these minerals, the equation with four parameters may be used in contrast with many standard equations applied for kinetic studies in soils. Sorption was described to take place in two processes: a fast one that takes place in less than 45 min and a slow one that takes place in several hours or more. The rate of the slow process did not depend directly on the concentration of phosphate compounds in solution, but depended linearly on the amount of phosphate that was adsorbed during the fast process. These initially adsorbed ions carrying some amount of negative charge likely hindered the movement of subsequent adsorbate ions to the solid surface due to decreased surface potential. This caused the variation in fast and slow sorption rate constants. Sorption densities increased in the order, Pi >Gly P >G6P >IHP, which revealed that the sorption density and initial sorption rate of OPs decreased with increasing molecular weights of OPs.

Comprehensive analysis of water vapor sorption kinetics and mechanisms using biosorbent pellets from canola meal and oat hull

Agricultural residues, specifically canola meal (CM) and oat hull (OH), have been innovatively utilized to develop biosorbents for sorbing water vapor from the air. These biomaterials are comprised of hydrophilic functional groups that effectively perform air dehydration. Air, being non-polar, was used as a model gas in this study to simulate gas dehydration. In the current research, these materials were formed into pellets to produce high-quality biosorbents with controlled size, shape, and enhanced moisture uptake capacity. CM (309.48 mg/g) and OH (233.07 mg/g) pellets had higher or comparable water sorption capacities than commercialized adsorbents used for drying gases. The mixed-order kinetic model described the sorption process well and identified both mass transfer and sorption on active site steps (R 2 > 0.991 and χ 2 < 16.0). Regarding the OH pellet, sorption on active sites was the predominant kinetic mechanism at the beginning, followed by intraparticle diffusion until equilibrium. However, sorption on CM pellets was delayed at 4.2 min at the initial stage, owing to the external mass transfer resistance; then, intraparticle diffusion controlled the process until equilibrium. Adding sodium lignosulfonate (LSNa) lowered the initial sorption rate but enhanced the water uptake and strength of pellets. The addition of LSNa resulted in a 25% and 14% increase in the water uptake capacity of oat hull and canola meal pellets, respectively; conversely, it also caused an increase in the delay time for sorption on CM pellets at the beginning of the process, extending it to 9.50 min.

Sorption of colored vs. noncolored organic matter by tidal marsh soils

Abstract. Tidal marshes are significant sources of colored (or chromophoric) dissolved organic carbon (CDOC) to adjacent waters and, as a result, contribute substantially to their optical complexity and ultimately affect their water quality. Despite this, our mechanistic understanding of the processes that regulate the exchange and transformation of CDOC at the tidal marsh–estuarine interface remains limited. We hypothesized that tidal marsh soils regulate this exchange and transformation subject to soil mineralogy and salinity environment. To test this hypothesis, we generated initial mass sorption isotherms of CDOC and noncolored dissolved organic carbon (NCDOC) using anaerobic batch incubations of Great Dismal Swamp DOC with four tidal wetland soils, representing a range of organic carbon content (1.77 ± 0.12 % to 36.2 ± 2.2 %) and across four salinity treatments (0, 10, 20, and 35). CDOC sorption followed Langmuir isotherms that were similar in shape to those of total DOC, but with greater maximum sorption capacity and lower binding affinity. Like isotherms of total DOC, CDOC maximum sorption capacity increased and binding affinity decreased with greater salinity. Initial natively adsorbed colored organic carbon was low and increased with soil organic content. In contrast, NCDOC desorbed under all conditions with desorption increasing linearly with initial CDOC concentration. This suggests that for our test solutions CDOC displaced NCDOC on tidal marsh soils. Parallel factor analysis of 3-D excitation emission matrices and specific ultraviolet absorbance measurements suggested that CDOC sorption was driven primarily by the exchange of highly aromatic humic-like CDOC. Taken together, these results suggest that tidal marsh soils regulate export and composition of CDOC depending on the complex interplay between soil mineralogy, water salinity, and CDOC vs. NCDOC composition.

Modeling Mn(II) autocatalytic sorption on MnOx-coated filtration media

This study reports a newly developed kinetic model for predicting manganese (Mn) removal in Mn-coated filtration media. Manganese oxides (MnOx) adsorb and catalyze the oxidation of Mn in the liquid phase to regenerate sorption sites. The most common kinetic models (pseudo-first- and second-order models) do not consider the regeneration of reactive sites, thereby inadequately describing the long-term uptake of Mn(II) by MnOx. We propose a new kinetic model that considers both the rapid initial sorption of Mn(II) onto MnOx and its subsequent slow oxidation to Mn(Ox). This model was generalized to account for different pH, temperatures, and initial Mn concentrations. The enhanced model demonstrated a prediction error of +/−1 % on the Mn(II) concentration measured in the column effluent of two different MnOx media recovered from industrial filters. Although the contribution of oxidation was found to be 10 times smaller than that of adsorption, it is important to consider if for the prediction of Mn(II) uptake over a 4-h column experiment.

Synergistic effects of CeO2 and Al2O3 on reactivity of CaO-based sorbents for CO2 capture

The calcium looping (CaL) process, comprising reversible calcination and carbonation reactions with CO2 and CaO-based sorbents, stands out as a highly promising industrial approach for CO2 capture. A significant challenge, however, is the swift degradation of the reactivity of CaO-based sorbents. In this study, CeO2-stabilized and CeO2/Al2O3 co-stabilized CaO-based sorbents were produced via a Pechini technique. Results indicated that incorporating CeO2 enhanced the CO2 sorption performance of CaO-based sorbents. The most effective CeO2-stabilized CaO-based sorbents (a CeO2/CaO mass ratio of 15:85) demonstrated an initial sorption capacity of 0.479 gCO2/gmaterial, undergoing a 41% reduction in its initial reactivity by the 20th cycle. To enhance CO2 sorption stability and reduce the high cost linked with the expensive cerium precursor, Al2O3 was introduced as the second stabilizer into the CeO2-stabilized CaO-based sorbents. When the CeO2/Al2O3/CaO mass ratio was adjusted to 5:10:85, the CO2 sorption capacity of CeO2/Al2O3 co-stabilized CaO-based sorbents reached 0.354 gCO2/gmaterial in the 20th cycle. This represented only a 17.7% reduction in its initial performance, surpassing the CeO2-stabilized counterpart by 26.3%. Comprehensive characterizations, including scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), and electron paramagnetic resonance (EPR), revealed that incorporating Al2O3 into the CeO2-stabilized CaO-based sorbents served a dual purpose: acting as a stable framework to inhibit pore structure deterioration and increasing the concentration of oxygen vacancies. In consequence, the synergistic effect of CeO2 and Al2O3 improved both structural stability and oxygen vacancy concentration of the sorbents, ultimately leading to superior CO2 sorption performance.

Efficient removal of tizanidine and tetracycline from water: A single and competitive sorption approach using carboxymethyl cellulose granulated iron-pillared clay

This study deals with the development of a granulated Fe-pillared clay (Fe-PC) using carboxymethylcellulose (CMC) as a binder to present it as an innovative adsorbent for the individual and competitive adsorption of tetracycline (Tc) and tizanidine (Tz) from water. An optimum pH value of 7 was determined for both individual and multi-component adsorption. The optimal dosage of granulated Fe-PC was determined to be 1.5 g/L for Tz and 3 g/L for Tc, resulting in constant removal rates of 80 % for Tc and 90 % for Tz. Tizanidine showed a higher affinity for powdered or granulated Fe-PC compared to tetracycline, due to its smaller molecular size and increased amine functional groups. Consequently, Tz showed improved kinetic rates (initial pseudo-second order sorption rates of 170.79 and 25.62 mg/g.h for Tz and Tc, respectively) and equilibrium capacities (maximum monolayer adsorption capacity of granulated Fe-PC at room temperature over Tc and Tz, 54.89 mg/g and 66.40 mg/g). Granulation affected the kinetic rate for both adsorbates, albeit with a more pronounced effect for Tc. The adsorption of Tz was less sensitive to temperature changes, indicating a lower enthalpy change of adsorption (14.24 and 77.91 kJ/mol for Tz and Tc, respectively). HCl for Tc and NaCl for Tz were identified as optimal desorption eluents, confirming the involvement of cation exchange in Tz adsorption. Surface functional group analysis confirmed the proposed complexation mechanisms. Tz consistently showed a higher affinity for granular Fe-PC than Tc, especially at lower adsorbent dosages. This article provides a comprehensive insight into the characterization of the prepared adsorbents and their cyclic adsorption-desorption performance for Tc and Tz.

Gd2O3/CdS Nanocomposites were Synthesized for Photocatalytic Elimination of Methyl Blue (MB) Dye Under Visible Light Irradiation

Water contamination with hazardous dyes is a serious environmental issue that concerns humanity. A green technology to resolve this issue is the use of highly efficient photocatalysts under visible light to degrade these organic molecules. Adding composite and modifying shape and size on semiconductor materials are attempts to improve the efficacy of these compositions. The optical, microstructural and photocatalytic features of the compositions were investigated by several characterization procedures such as XRD, XPS, SEM, and TEM. Here, modifies Scherrer equation, Williamson–Hall (W–H), and Halder–Wagner method (H–W) have been used to investigate the crystal size and the micro-strain from the XRD peak broadening analysis. The average crystal size according to Modified Scherrer’s formula was 6.04–10.46 nm for pristine CdS and CdS/Gd2O3@GO, respectively. While the micro-strain (ɛ) corresponds to 3.88, 4.63, 4.03, and 4.15 for CdS, Gd2O3, CdS/Gd2O3, and CdS/Gd2O3@GO. It was also shown that the modest difference in average crystal size acquired by the Modified Scherrer and Halder–Wagner (HW) forms was related to differences in average particle size classification. As a result, the Halder–Wagner method was accurate in estimating crystallite size for the compositions. The average roughness is slightly changed from 4.4 to 4.24 nm for CdS/Gd2O3 and CdS/Gd2O3@GO, respectively. A kinetics investigation further revealed that the photocatalytic degradation of MB dyes was accompanied by a Langmuir isotherm and a pseudo-second-order reaction rate. The highest adsorption capacity (qe) determined for (type 1) CdS, Gd2O3, CdS/Gd2O3, and CdS/Gd2O3@GO adsorption was 5, 0.067, 0.027, and 0.012 mgg−1, respectively. The R2 values originated from the pseudo-second-order (type 2) for CdS, Gd2O3, CdS/Gd2O3, and CdS/ Gd2O3@GO were 0.904, 0,928, 0.825, and 0.977. As a result, the initial sorption rate (h) is altered between types 1 and 2. In type 2, the pseudo-second-order rate constant (k2) ranges from 0.005 for CdS to 0.011 for CdS/Gd2O3@GO. The Langmuir Hinshelwood and pseudo-second-order kinetic models describe the photodegradation process. The results demonstrate that the developed compositions can be used as a long-term substance for dye removal.

Innovative Sol-gel functionalized polyurethane foam for sustainable water purification and analytical advances.

Nanomaterial combined polymeric membranes such as polyurethane foams (PUFs) have garnered enormous attention in the field of water purification due to their ease of management and surface modification, cost-effectiveness, and mechanical, chemical, and thermal properties. Thus, this study reports the use of novel Sol-gel impregnated polyurethane foams (Sol-gel/PUFs) as new dispersive solid phase microextractors (d- µ SPME) for the efficient separation and subsequent spectrophotometric detection of Eosin Y (EY) textile dye in an aqueous solution with a pH of 3-3.8. The Sol gel, PUFs, and Sol gel-impregnated PUFs were characterized using scanning electron microscopy (SEM), goniometry measurements, dynamic light scattering (DLS), energy dispersive spectroscopy (EDS), UV-Visible, and FTIR spectra. Batch experiment results displayed a remarkable removal percentage (96% ± 5.4%) of the EY from the aqueous solution, with the total sorption time not exceeding 60min. These data indicate rate-limited sorption via diffusion and/or surface complex ion associate formations after the rapid initial sorption steps. A pseudo-second order kinetic model thoroughly explained the sorption kinetics, providing a sorption capacity (qe) of 37.64mgg-1, a half-life time (t1/2) of 0.8 ± 0.01min, and intrinsic penetration control dye retention. The thermodynamic results revealed a negative value for ΔG⁰ (-78.07kJmol-1 at 293K), clearly signifying that the dye uptake was spontaneous, as well as a negative value for ΔH⁰ (-69.58kJmol-1) and a positive value for ΔS⁰ (147.65Jmol-1 K-1), making clear the exothermic nature of EY adsorption onto the sorbent, with a growth in randomness at the molecular level. A ternary retention mechanism is proposed, involving the "weak base anion exchanger" of {(-CH2-OH+ -CH2-) (Dye anion)-}Sol-gel/PUF and/or {(-NH2 + -COO-) (Dye anion)-}Sol-gel/PUF via solvent extraction and "surface adsorption" of the dye anion on/in the Sol-gel/PUFs membranes in addition to H-bonding, including surface complexation and electrostatic π-π interaction, between the dye and the silicon/zirconium oxide (Si-O-Zr) and siloxane (Si-O-Si) groups on the sorbent. Complete extraction and recovery (93.65 ± 0.2, -102.28 ± 2.01) of EY dye with NaOH (0.5M) as a proper eluting agent was achieved using a sorbent-packed mini column. In addition, the established extractor displayed excellent reusability and does not require organic solvents for EY enrichment in water samples, making it a talented nominee as a novel sorbent for EY sorption from wastewater. This study is of great consequence for expanding the applicatio1n of Sol-gel/PUFs in developing innovative spectrophotometric sensing strategies for dye determination. In view of this, it would also be remarkable to perform future studies to explore the analytical implications of this extractor regarding safety and environmental and public health issues associated to the pollutant.

Synthesis and Sorption Profiles of Graphene‐Decorated Silane‐Modified Layered Clays for As(V) Removal: A Quantitative Assessment and Mechanistic Insights

AbstractA novel adsorbent material, graphene decorated silane modified layered clays enriched with Fe(III) (TEOS‐g‐LDH−Fe/rGO) was prepared via emulsion polymerization followed by in situ precipitation and its physicochemical characterization carried out by FTIR, XRD, SEM‐EDS, HRTEM, TG‐ DTG, XPS and Raman analysis. The TEOS‐g‐LDH−Fe/rGO composite utilized for the effective removal of As(V) from aqueous system and the process followed via inner‐sphere surface complexation through ligand exchange between hydroxyl groups in TEOS‐g‐LDH−Fe/rGO and As(V) species. The equilibrium data fitted well with Langmuir model and kinetic data with mixed batch model showed remarkable adsorption capacity of 103.91 mg/g at pH 5.5. The synergistic effects associated with precursors in the composite profoundly improved the removal efficiency of As(V). The optimal conditions for As(V) removal was evaluated by RSM coupled with central composite design(CCD) considering pH(3–6), dose(0.5–2.5) and time (1–80 min) at temperature 30 °C. The sorption efficacy of TEOS‐g‐LDH−Fe/rGO was found to be about four times greater than its precursors. In simulated water matrix, the TEOS‐g‐LDH−Fe/rGO exhibit a retention of sorption performance (90 %) from 98.8 % of its initial sorption capacity for As(V) removal during regeneration. This work proves TEOS‐g‐LDHFe/rGO as a promising candidate for addressing grievous environmental threats from arsenic contamination.

Dual synergistic effect of the amine-functionalized MIL-101@cellulose sorbents for enhanced CO2 capture at ambient temperature

The development of high carbon dioxide (CO2) sorption capacity materials is necessary for the deployment of the CO2 capture and storage strategy. Metal-organic frameworks (MOFs) have emerged as promising substitutes for traditional liquid and solid CO2 capture sorbents due to their high surface area, tunable pore size, diverse composition, and various physical and chemical properties. However, MOFs feature the intrinsic limitations of powder agglomeration, weak binding affinity, and sluggish diffusion kinetics, thus hindering their industrial application in CO2 capture. Herein, we design an amine-functionalized MIL-101@cellulose (NH2-MIL-101@BM) composite sorbent by anchoring NH2-MIL-101 nanoparticles onto the BM matrix through hydrogen bonding interaction. The dual synergistic effect, origin from the physical sorption synergistic effect and chemisorption synergistic effect proposed between NH2-MIL-101 and BM, not only facilitates the mass transfer of CO2 by reducing the diffusion resistance through hierarchical-pore structure but also offers stronger sorption sites with CO2 by increasing the adsorption energy of metal-CO2 or amine-CO2, which are confirmed by series of characterizations and theory functional calculations. Benefiting from the above merits, the NH2-MIL-101@20 %BM sorbent delivers a superior initial CO2 sorption capacity of 13.4 mmol/g when the BM doping amount is 20 wt% at 25 °C, and also shows good recycle stability even after 15 runs with maintainable structure. This work displays the in-depth mechanism understanding for enhanced CO2 capture, providing value inspiration for future MOF-based composite sorbent construction for CO2 capture at ambient temperatures.

Impacts of multi-pollutants on sulfonamide antibiotic removal from water matrices using layered double hydroxide sorbents

Remediation of sulfamethoxazole (SMX) present in the aqueous environment requires the development of new advanced wastewater treatment technologies, crucial to reduce the toxicity of such pollutants to the environment, supporting urban water reuse. Continuously synthesised layered double hydroxides (LDH) have been applied as a sorbent material for the removal of SMX from water. No equilibrium uptake of SMX was observed from any water matrix. However, an unusual sorption/release behaviour of SMX was observed in the presence of Mg2Al-NO3-LDH, influenced by the characteristics of the water matrix. A maximum SMX removal percentage of 34.7% was reached within 10 min, from ultrapure water, followed by release of SMX back into solution over the following 24 h. Further, Mg2Al-NO3-LDH is shown to release NO3- into all water matrices. It is proposed that NO3- disrupts the SMX-LDH interactions, resulting in release of SMX from the LDH. No initial SMX sorption was observed onto Mg2Al-NO3-LDH when wastewater effluent was the water matrix, likely due to competition for sorption sites on the LDH with multiple pollutants, including metals and additional anionic nutrients, present in the wastewater. This work illustrates the potential for relationships between the sorbent material and water matrix interactions on pollutant sorption behaviour. In addition, the findings highlight the importance of conducting removal experiments at realistic environmental conditions to ensure development of suitable sorbent materials for pollutant remediation.

Discovery and In Situ Crystallization Studies of Cerium-Based Metal-Organic Frameworks with V-Shaped Linker Molecules.

We report the discovery and characterization of two porous Ce(III)-based metal-organic frameworks (MOFs) with the V-shaped linker molecules 4,4'-sulfonyldibenzoate (SDB2-) and 4,4'-(hexafluoroisopropylidene)bis(benzoate) (hfipbb2-). The compounds of framework composition [Ce2(H2O)(SDB)3] (1) and [Ce2(hfipbb)3] (2) were obtained by using a synthetic approach in acetonitrile that we recently established. Structure determination of 1 was accomplished from 3D electron diffraction (3D ED) data, while 2 could be refined against powder X-ray diffraction (PXRD) data using the crystal structure of an isostructural La-MOF as the starting model. Their framework structures consist of chain-like inorganic building units (IBUs) or hybrid-BUs that are interconnected by the V-shaped linker molecules to form framework structures with channel-type pores. The composition of both compounds was confirmed by PXRD, elemental analysis, as well as NMR and IR spectroscopy. Interestingly, despite the use of (NH4)2[CeIV(NO3)6] in the synthesis, cerium ions in both MOFs occur exclusively in the + III oxidation state as determined by X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). Thermal analyses reveal remarkably high thermal stabilities of ≥400 °C for the MOFs. Initial N2 sorption measurements revealed the peculiar sorption behavior of 2 which prompted a deeper investigation by Ar and CO2 sorption experiments. The combination with nonlocal density functional theory (NL-DFT) calculations adds to the understanding of the nature of the different pore diameters in 2. An extensive quasi-simultaneous in situ XANES/XRD investigation was carried out to unveil the formation of Ce-MOFs during the solvothermal syntheses in acetonitrile. The crystallization of the two Ce(III)-MOFs presented herein as well as two previously reported Ce(IV)-MOFs, all obtained by a similar synthetic approach, were studied. While the XRD patterns show time-dependent MOF crystallization, the XANES data reveal the presence of Ce(III) intermediates and their subsequent conversion to the MOFs. The addition of acetic acid in combination with the V-shaped linker molecule was identified as the crucial factor for the formation of the crystalline Ce(III/IV)-MOFs.

Sorption-enhanced biogas steam reforming over the Pb-modified Ni–CaO bifunctional catalysts

Sorption-enhanced biogas steam reforming (SESRB) can efficiently produce high-purity “green hydrogen” from biogas with the adaptability to high and variable CO2 content of biogas. The key challenge faced by SESRB is the rapid, sintering-induced decline of sorption capacity. Herein, a Pb-modified Ni–CaO bifunctional catalyst is prepared based on the adsorption of Pb2+ by CaCO3, in which the replacement of CaCO3 by PbCO3 is achieved on the surface of CaCO3. After thermal treatment, CaPbO3 was generated on the surface of CaO particles in the bifunctional catalyst, by which CaO particles are separated effectively, and thus the sintering of Ca species is weakened. 5Ni–8PbO–CaO as the optimum catalyst with only 7.9 wt% PbO maintains 57.6 % of the initial sorption capacity after 20 cycles, higher than that of 5Ni–CaO (40.5 %). Due to the excellent stability of the 5Ni–8PbO–CaO catalyst, high-purity hydrogen (94.1 vol%) with 95.0 % CH4 conversion is continuously obtained from biogas for 20 consecutive SESRB-decarbonation cycles.

Influence of Barrier Layers on ZrCoCe Getter Film Performance.

Improving the vacuum degree inside the vacuum device is vital to the performance and lifespan of the vacuum device. The influence of the Ti and ZrCoCe barrier layers on the performance of ZrCoCe getter films, including sorption performance, anti-vibration performance, and binding force between the ZrCoCe getter film and the Ge substrate were investigated. In this study, the Ti and ZrCoCe barrier layers were deposited between the ZrCoCe getter films and Ge substrates. The microtopographies of barrier layers and the ZrCoCe getter film were analyzed using scanning electron microscopes. The sorption performance was evaluated using the constant-pressure method. The surface roughness of the barrier layers and the getter films was analyzed via atomic force microscopy. The binding force was measured using a nanoscratch tester. The anti-vibration performance was examined using a vibration test bench. The characterization results revealed that the Ti barrier layer significantly improved the sorption performance of the ZrCoCe getter film. When the barrier material was changed from ZrCoCe to Ti, the initial sorption speed of the ZrCoCe getter film increased from 141 to 176 cm3·s-1·cm-2, and the sorption quantity increased from 223 to 289 Pa·cm3·cm-2 in 2 h. The binding force between the Ge substrate and the ZrCoCe getter film with the Ti barrier layer was 171 mN, whereas that with the ZrCoCe barrier layer was 154 mN. The results showed that the Ti barrier layer significantly enhanced the sorption performance and binding force between the ZrCoCe getter film and the Ge substrate, which improved the internal vacuum level and the stability of the microelectromechanical system vacuum devices.

Oil Adsorption Kinetics of Calcium Stearate-Coated Kapok Fibers.

This study used a simple and efficient dipping method to prepare oleophilic calcium stearate-coated kapok fibers (CaSt2-KF) with improved hydrophobicity. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) confirmed the deposition of calcium stearate particles on the surface of the kapok fibers. This led to higher surface roughness and improved static water contact angle of 137.4°. The calcium stearate-coated kapok fibers exhibited comparable sorption capacities for kerosene, diesel, and palm oil. However, the highest sorption capacity of 59.69 g/g was observed for motor oil at static conditions. For motor oil in water, the coated fibers exhibited fast initial sorption and a 65% removal efficiency after 30 s. At equilibrium, CaSt2-KF attained a sorption capacity of 33.9 g/g and 92.5% removal efficiency for motor oil in water. The sorption kinetics of pure motor oil and motor oil in water follows the pseudo-second-order kinetic model, and the Elovich model further described chemisorption. Intraparticle diffusion and liquid film diffusion were both present, with the latter being the predominant diffusion mechanism during motor oil sorption.

Hollow polyester/kapok/hollow polyester fiber-based needle punched nonwoven composite materials for rapid and efficient oil sorption.

Nowadays oil pollution poses a serious threat to the environment and people's daily life. As reusable and environmentally friendly materials, fiber-based oil sorption materials can effectively alleviate this phenomenon. However, maintaining a high sorption rate along with improved mechanical properties remains a challenge for oil sorption materials. Herein, we report a novel hollow PET/kapok/hollow PET nonwoven with high porosity and oil retention, outstanding cyclic oil sorption rate and improved mechanical performance using kapok as the oil preserver and hollow PET as the conductor and structure enhancer. Benefiting from the three-layer composite structure fabricated by carding and needle punching reinforcement, the resulting oil sorption materials, with kapok proportion more than or equal to 60%, exhibited high oil sorption rate and oil sorption speed. The materials of 20HP/60K/20HP component content present a high initial oil sorption rate of 28.22 g g-1, a maximum oil sorption rate of 31.17 g g-1 and a sorption rate constant of the Quasi second-order kinetic equation of 0.067 in plant oil. On the other hand, when the proportion of kapok fiber in the material was below 60%, due to the introduction of hollow PET, the mechanical properties were significantly boosted, and its oil retention and reusability were distinguished, with a reuse rate stabilizing at a relatively high level (>93%) in plant oil after undergoing three oil sorption cycles. The successful fabrication of hollow PET/kapok/hollow PET nonwovens could provide a new approach for the design and development of oil sorption materials.

Effect of oxygen addition on phase composition and activation properties of TiFe alloy

TiFe is one of the most promising hydrogen storage materials owing to its high volumetric hydrogen capacity, moderate operating temperature, and low cost. Oxygen is an inevitable impurity that affects the hydrogen storage properties of TiFe alloys. In this paper, the effect of oxygen addition on the phase composition and hydrogen storage properties of TiFe alloys is systematically investigated. We found that a high oxygen addition improves the initial hydrogen sorption of TiFe. The TiFe-O3.78 alloy achieves full activation after two ab/desorption cycles at room temperature. The high oxygen content facilitates the formation of Ti4Fe2O oxide in TiFe alloy, leading to improved activation kinetics. Moreover, due to the oxygen addition, the amount of TiFe primary phase reduces, and the corresponding hydrogen capacity degrades. Increasing oxygen content also leads to a slight increase in the hydrogenation equilibrium pressure, but almost no impact on the thermodynamics of TiFe alloy.