Good Porous Structure Research Articles

Catalytic pyrolysis of spent bleaching clay for its regeneration and simultaneously producing aromatic hydrocarbons

This study was focused on the value-increment of spent bleaching clay (SBC) to produce aromatic hydrocarbons and regenerated bleaching clay (RBC) via ex-situ catalytic pyrolysis with HZSM-5. The catalytic pyrolysis experiments were conducted to clarify the regulatory functions of pyrolytic temperature and SBC-to-HZSM-5 ratio (S/H) on the product distribution and aromatics generation. The adsorbed oil in SBC could be decomposed almost completely at 450 °C. The optimum aromatics yield of 3.49 wt% was achieved at catalytic temperature of 600 °C and S/H of 15. The solid product obtained under this condition underwent calcination at 500 °C and acid treatment successively to prepare RBC. The treatment did not affect the montmorillonite structure of clay. The RBC possessed good porous structures with newly generated micropores. The specific surface area and pore volume of RBC reached 163.32 m2/g and 0.29 cm3/g, higher than those of 146.17 m2/g and 0.25 cm3/g of fresh activated bleaching clay (ABC), indicating the better adsorption performance of RBC.

Waste liquid-added regeneration activator to enhance the pore structure and compressive strength of geopolymer-foam-fiber: A sustainable strategy of kenaf fiber pretreatment and reuse

Developing good pore structure, high-strength inorganic insulation materials derived from fiber-reinforced foaming geopolymer, is desirable for several applications. In this paper, a low-cost, eco-friendly, and high-efficiency method was proposed for processing alkali-treated kenaf fibers (TKF) and metakaolin geopolymer into lightweight yet strong bulk structure geopolymer-foam-fiber (GFF). The composites were produced using H2O2 as foaming agent. The waste liquid of TKF and activator (NaOH and Na2SiO3) were mixed and considered as the regenerating activator. Disordered TKF and regenerating activator with higher viscosity play a crucial role in the mechanical and pore structure of the composites. The results showed that when the foaming agent content increased, the compressive strength of composites decreased. The record-high compressive strength of geopolymer-foam (GF) increased by 1.1–2.1 times and 1.2–2.7 times for ambient temperature and 50 ℃, respectively. GFF with homogeneous pore distribution and high porosity were successfully fabricated by introducing TKF. Therefore, the thermal conductivity and compressive strength were in the ranges of 0.118–0.248 W/(m·k) (comparable to GF) and 1.6–19.9 MPa (1.1–2.6 times increase compared with GF), respectively. This low-cost and no-waste production of geopolymer foam material can enhance the utilization of agricultural waste and the development of inorganic insulation materials.

A novel pathway based on the comprehensive utilization of oil peony pods into high yield polysaccharides and strong adsorption carbon

The main purpose of the study was to establish a new comprehensive utilization Standard Operating Procedure (SOP) for the oil tree peony pods (OTPP) and realize the green sustainable utilization of agricultural and forestry waste. The OTPP polysaccharide (OTPP-P) was extracted by ultrasonic-assisted extraction (UAE), and the yield was optimized by response surface methodology (RSM). The activated carbon (AC) was prepared by two-step activation using OTPP residue (OTPPR) as raw material, and the structure and adsorption properties of AC were evaluated. The results revealed that the yield of OTPP-P was up to 8.05% by UAE, two polysaccharides were isolated from OTPP-P, and the monosaccharides components were obtained. The PPAC-KOH had a good pore structure (SBET = 1363.39 m2/g and VTotal = 0.81 cm3/g), and had superior adsorption capacity for methyl orange (1113 mg/g), ciprofloxacin (696 mg/g) and norfloxacin (308 mg/g). The adsorption process mainly included electrostatic interaction, π-π interactions, and dominant physical absorption. Adsorption had good applicability and repeatability. This study provided a new way for the comprehensive utilization of OTPP and a reference for the high value-added transformation and sustainable development of waste.

Characteristics and Formation Mechanism of Multiscale Storage Spaces in Ancient Deep Tight Reservoirs: Examples from the Cambrian Yurtus Formation in the Northern Tarim Basin, China

AbstractUnder the background of complicated diagenetic fluids, high-temperature pressure in superimposed basin, the pore-forming and pore-preserving effects of deep tight reservoirs are complex, and the formation mechanism of high-quality reservoirs has always been the core issue. With the discovery of oil and gas in ultradeep drilling in Tarim Basin, the most unconventional tight reservoir of Lower Cambrian Yuertus Formation in Tabei area began to receive attention. Based on the research of typical field outcrops in Tabei area, the lithofacies, reservoir space differences, and reservoir formation mechanism are systematically analyzed. (1) The stratum has undergone complex multistage diagenetic fluid transformation, and the rock types are diverse with great differences; siliceous rock and dolomite are the main rock types, often in thin-medium layered distribution. (2) After long-term deep burial transformation, siliceous rock and dolomite can still retain a large number of effective storage spaces; hydrothermal dissolution pores, organic acid dissolution pores, atmospheric freshwater dissolution pores, and intercrystalline pores are the main pore types, which provide main storage spaces. Multiscale pores are developed in siliceous rock and dolomite, with good connectivity and good pore structure. (3) The large-scale storage spaces mainly come from the effective maintenance of primary pores, organic matter, and hydrothermal dissolution. The siliceous minerals and dolomite have stable properties and strong resistance to compaction and can effectively maintain the early pores. (4) The large-scale reservoir space was formed in the early diagenetic stage; the pressure-solution and cementation are the two most important diagenetic processes for reducing storage spaces; however, under the pore-forming and pore-preserving effects of early silicification and dolomitization, various types of dissolution, and oil charging, the tight lithology can still maintain effective storage spaces. The related research has important theoretical and practical significance for studying the formation mechanism of tight reservoirs in deep ancient strata and predicting high-quality reservoirs.

Experimental study on the physico-mechanical properties and microstructure of foam concrete mixed with coal gangue

Coal seam fires are a significant disaster in coal mine production. In order to prevent spontaneous coal combustion, it is necessary to build airtight walls in areas such as mined-out areas or working face roadways. Coal gangue (CG) is a solid waste produced in coal mine production, causing ecological damage and resource waste. So in this paper, a coal gangue lightweight foam concrete is developed for confined filling in coal mines. The effect of water-binder ratio(w/b), CG content, fly ash(FA) content, and foam content on the compressive strength, dry density, water absorption, and porosity of coal gangue foam concrete was analyzed in the single-factor and orthogonal experiment. It was found that the w/b and foam content were the two factors with a more significant effect on the mechanical properties of the specimens. For the porosity of the specimens, the amount of CG content is the critical factor that affects them. A scanning electron microscope (SEM) analyzed the specimen's microstructure and observed its pore structure. It was found that the amount of CG content would significantly affect the specimen's microstructure. When the CG content was 30%, the specimen had the best performance index of pores and poor connectivity between pores. This study shows that the foam concrete mixed with CG can have good mechanical properties and pore structure, making a valuable reference for the coal gangue foam concrete for the confinement filling treatment in mined-out areas or working face roadways mines.

Gelatin-Oxidized Nanocellulose Hydrogels Suitable for Extrusion-Based 3D Bioprinting

3D bioprinting is an emerging research field developed by the deep cross-fertilization of 3D printing technology with multiple disciplines such as mechanics, materials, and biomedicine. Extrusion 3D bioprinting, the most widely used 3D bioprinting technology, can print biomaterials with different viscosities and has a wide range of material applicability. In this study, we prepared a composite hydrogel with gelatin-oxidized nanocellulose as the matrix and glycerol as a multifunctional co-solvent, and the optimal composition of the hydrogel was determined by material characterization. The microstructure of the hydrogel was visualized by scanning electron microscopy (SEM), and it can be seen that the composite hydrogel material has a three-dimensional porous network structure with microporous pore sizes ranging from 200–300 µm. The infrared spectra also showed that the addition of glycerol did not interact with gelatin-oxidized nanocellulose while improving the hydrogel properties. Meanwhile, the composite hydrogel has obvious shear-thinning properties and good mechanical properties, which are suitable for extrusion-based 3D bioprinting, and the printed area is clear and structurally stable. A series of results indicate that the hydrogel is suitable for extrusion-based 3D bioprinting with good pore structure, mechanical properties, and printable performance. This gelatin-oxidized nanocellulose hydrogel provides a new idea and material for 3D bioprinting and expands the potential uses of the material.

The Frontiers of Functionalized Nanocellulose-Based Composites and Their Application as Chemical Sensors.

Chemical sensors are a rapidly developing technology that has received much attention in diverse industries such as military, medicine, environmental surveillance, automotive power and mobility, food manufacturing, infrastructure construction, product packaging and many more. The mass production of low-cost devices and components for use as chemical sensors is a major driving force for improvements in each of these industries. Recently, studies have found that using renewable and eco-friendly materials would be advantageous for both manufacturers and consumers. Thus, nanotechnology has led to the investigation of nanocellulose, an emerging and desirable bio-material for use as a chemical sensor. The inherent properties of nanocellulose, its high tensile strength, large specific surface area and good porous structure have many advantages in its use as a composite material for chemical sensors, intended to decrease response time by minimizing barriers to mass transport between an analyte and the immobilized indicator in the sensor. Besides which, the piezoelectric effect from aligned fibers in nanocellulose composites is beneficial for application in chemical sensors. Therefore, this review presents a discussion on recent progress and achievements made in the area of nanocellulose composites for chemical sensing applications. Important aspects regarding the preparation of nanocellulose composites using different functionalization with other compounds are also critically discussed in this review.

Design and direct preparation of a novel silicon carbide support for zeolite membrane

The support for the membrane is the basis for the preparation and application of the zeolite membrane. Moreover, its cost and properties directly determine the performance of the zeolite membrane and its industrial applications. A novel porous silicon carbide (SiC) support for zeolite membrane bonded with needle-like mullite (3Al2O3·2SiO2) was prepared using SiC powders as the raw material and kaolin, Al(OH)3, and AlF3 as the needle-like mullite precursor additives via an in situ high-temperature reactions in an air atmosphere. Effects of the support material composition and the sintering temperature on the sintering behavior, pore structure, permeability, and microstructure of the resultant supports were extensively investigated. The needle-like mullite formation consumed silicon oxide (SiO2) and generated a rigid skeleton structure with a good pore structure and bonding phase. Hence, the porous SiC support exhibited high porosity, with relatively large pore size and mechanical strength, which helped improve the support performance. Notably, the porous SiC support sintered at 1480 °C with in situ inter-particle needle-like mullite bonding exhibited excellent filtration and permeability performance. The porous support materials and methods used in this work are suitable for designing and preparing a novel porous SiC support for zeolite membranes.

Genipin modified lyophilized platelet-rich fibrin scaffold for sustained release of growth factors to promote bone regeneration.

Lyophilized platelet-rich fibrin (L-PRF) was shown to further activate resident platelets in platelet-rich fibrin causing a higher amount of growth factors release. However, it still required further experimental studies to resolve the uncontrolled degradation and burst release problem. In this study, the nature crosslinker genipin is introduced to improve the performance of L-PRF scaffold. We used a series of gradient concentration genipin solutions to react with L-PRF. The crosslinking degree, micro morphology, mean pore size, water absorption and mechanical properties of the crosslinked scaffold were evaluated. In order to study the effect of genipin modification on the release kinetics of growth factors from L-PRF, we detected the release of platelet-derived growth factor, vascular endothelial growth factor and transforming growth factor in vitro by ELISA. To investigate the biodegradability of the crosslinked L-PRF in vivo, the scaffolds were transplanted subcutaneously into backs of rats, and the materials were recovered at 1, 2 and 4 weeks after implantation. The biodegradation, inflammatory reaction and biocompatibility of the scaffolds were examined by histological staining. Finally, the genipin crosslinked/uncrosslinked L- Platelet-rich fibrin scaffolds were implanted with freshly prepared SHED cell sheets into rat critical size calvarial defects and the skull samples were recovered to examine the treatment efficacy of genipin crosslinked L-PRF by histologic and radiographic approaches. Results of this study indicated that genipin can be used to modify L-PRF at room temperature at a very low concentration. Genipin-modified L-PRF shows better biomechanical performance, slower biodegradation, good bioavailable and sustained release of growth factors. The 0.01% w/v and 0.1% w/v genipin crosslinked L-PRF have good porous structure and significantly promote cell proliferation and enhance the expression of key genes in osteogenesis in vitro, and work best in promoting bone regeneration in vivo.

The mixed-potential NH3 sensor using BiVO4/Bi4V2O11 heterojunction sensing electrode prepared by self-phase separation

BiVO4/Bi4V2O11 heterojunction sensing materials for the mixed-potential NH3 sensor were prepared by the hydrothermal method and sequent heat treatment, accompanying self-phase separation. The influence of the Bi3+/V5+ mole ratios on phase composition, microstructure of sensing materials and the performances of the sensor was investigated. The samples with different Bi3+/V5+(1:1–2:1) calcined at 500 °C form non-stoichiometric Bi4V2O11 and Bi2VO5.5 and further calcination at 750 °C, all samples change into BiVO4/Bi4V2O11 heterojunction materials. The mixed potential sensors based on above-mentioned heterojunction materials and Ce0.8Gd0.2O1.9 electrolyte show excellent performance. The sensor based on sensing electrode with Bi3+/V5+=1.75:1 can stably work at 450–600 °C due to good porous structure of sensing electrode, which is conducive to gas diffusion and adsorption. At 500 °C, the sensor has the highest sensitivity and the lowest detection limit. The relationship between ΔV and logarithm of NH3 concentrations is piecewise linear in the range of 1–25 ppm and 25–300 ppm, and the sensitivity is −6.9 and −38.2 mV/decade, respectively. The cross-sensitivity test of the sensor shows that co-existent gas CO2, CH4, H2 or H2S makes the response value change −3.7%, −3.0%, 0.9% and −6.8%, showing good anti-interference performance to these gases. While NO or NO2 causes serious interference, making the response value reduce by −9% and −27%. CuO instead of Pt as the reference electrode nearly eliminates the interference of NO and NO2. In addition, sensor following the mixed potential mechanism was confirmed by experiments.

Supported Mn2O3-based catalysts for NO-SCO: an experimental study.

In this paper, the NO-SCO (the selective catalytic oxidation of NO) experiments of single-phase Mn2O3, supported Mn2O3/Al2O3, and the Ce-doped MnxCey/Al catalyst system were carried out. The physical and chemical properties of the catalysts were analyzed by XRD, BET, XPS, SEM, O2-TPD, and H2-TPR. The effects of loading and Ce doping on catalyst activity were studied. The results show that the Mn2O3 catalyst exhibited the best activity at 300 ℃, and the NO conversion rate of Mn2O3 was 78.2%. The relative content of Oα adsorbed on the surface of the Mnx/Al catalyst decreased obviously by loading Mn2O3 on γ-Al2O3, which led to the decrease in catalyst activity. And the temperature window moved to the high-temperature region. After doping Ce, the dispersion of Mn enhanced, and the relative content of oxygen Oα adsorbed on the surface increased. The low-temperature activity and fluidity of oxygen in catalysts were improved. Among them, the Mn0.2Ce0.08/Al catalyst obtained a high specific surface area, good pore structure, large oxygen storage capacity, and excellent surface oxygen species. The corresponding NO conversion rate reached 83.5% at 290 ℃. Then, the effects of operating parameters such as space velocity, NO concentration, and O2 content on the catalytic activity of Mn0.2Ce0.08/Al were discussed. The experimental results show that the NO conversion rate of Mn0.2Ce0.08/Al decreased with increasing NO concentration and space velocity. The O2 content had a positive effect on the catalytic activity of the catalyst. However, the NO conversion rate tended to be stable due to the saturation of oxygen adsorbed on the catalyst. Through cycling experiments, we found that Mn2O3, Mn0.2/Al, and Mn0.2Ce0.08/Al catalysts showed good oxidation stabilities for NO oxidation. The evaluation of the water and sulfur resistance of the catalyst shows that the toxicity of SO2 was reduced by the aqueous atmosphere to a certain extent. Through the structural optimization of the basic model and the calculation of the NO-SCO reaction path, the results show that the NO-SCO reaction on the Mn2O3 (110) face followed the ER mechanism more. For the Mn2O3/Al2O3 (110) surface, the LH-MvK hybrid mechanism can greatly reduce the desorption energy barrier of the reaction intermediates, which is more favorable for the NO-SCO reaction. The catalytic mechanisms of the MnxCey/Al catalysts require further in-depth research.

Optimizing Rice Husk Silica Mass and Sonication Time for a More Efficient and Environmentally Friendly Synthesis of SBA-15

By optimizing rice husk silica mass and sonication time, SBA-15 was successfully synthesized in a more efficient and environmentally friendly way. The solution of Pluronic P-123 was mixed with the solution containing NaOH and various masses of rice husk silica (4–12 g), followed by sonication for a certain time (30–150 min). The mixture was filtered and washed with distilled water and ethanol until neutral, then dried at 110 °C for 2 h and calcined at 500 °C for 6 h. The results showed that the optimal mass of rice husk silica was 8 g, while the optimal sonication time was 30 min. The product has a cylindrical pore shape with good crystallinity and pore structure regularity. The specific surface area (SBET), the pore diameter (DBJH), the specific pore volume (VBJH), and the wall thickness (WT) of the product were 601 m2 g–1, 4.76 nm, 0.88 mL g–1, and 5.02 nm, respectively. These results are not considerably different from the porosity of SBA-15, synthesized previously using conventional hydrothermal techniques from various silica sources. In addition, it is also comparable to the porosity of SBA-15 produced from TEOS by sonochemical methods as well as with commercial SBA-15.

N, P co-doped porous graphene with high electrochemical properties obtained via the laser induction of cellulose nanofibrils

Cellulose and its derivatives are natural materials with high carbon contents, but it is challenging to convert their carbon into high value-added carbonaceous materials (e.g., graphene). Here, an approach to convert the carbon in cellulose into N, P co-doped porous graphene (LIG) materials via laser induction is proposed. Cellulose nanofibrils (CNFs), a cellulose derivative with high dispersion uniformity and abundant surface hydroxyl groups, were easily formed on a bulk substrate (thickness ≥5 mm) containing ammonium polyphosphate (APP). Then, a 10.6 μm CO2 laser was used to scribe for 1–5 passes on the CNFs/APP substrate under an ambient environment to produce N, P co-doped porous LIG. Upon increasing the number of laser scribing passes, the IG/ID of LIG first increased and then decreased, reaching a maximum of 1.68 at 4 passes. The good pore structure and low resistance also showed that 4 laser passes were ideal. Besides, the N, P co-doped LIG also showed excellent electrochemical performance, with a specific capacitance of 221.4 F⋅g−1 and capacitance retention of 89.9%. This method exploits the advantages of nanocellulose and overcomes the difficulties associated with directly compounding cellulosic materials, providing a method for the further development of biomass nanomaterials.

Porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells and calcitriol for the repair of skull defect

There is an increasing demand for biomaterials with skull regeneration for clinical application. However, most of the current skull repair materials still have limitations, such as inadequate sources, poor cell adherence, differentiation, tissue infiltration, and foreign body sensation. Therefore, this study developed porous microsphere-based scaffolds containing mouse embryonic osteoblast precursor cells (MC3T3-E1 cells) and calcitriol (Cal) using gelatin and gelatin/hydroxyapatite through green freeze-crosslinking and freeze-drying. Gelatin was employed to prepare porous microspheres with a particle size of 100-300μm, containing open pores of 2-70μm and interconnected paths. Furthermore, the addition of Cal to porous gelatin microsphere-based scaffolds containing MC3T3-E1 cells (PGMSs-MC) and porous gelatin/hydroxyapatite composite microspheres containing MC3T3-E1 cells (HPGMSs-MC) improved their osteoinductivity and cell proliferation and promoted the formation of mature and well-organized bone. The developed Cal-HPGMSs-MC and Cal-PGMSs-MC displayed a good porous structure and cytocompatibility, histocompatibility, osteoconductivity, and osteoinduction. Thus, the designed scaffolds provide a promising prospect for tissue-engineered constructs with skull growth and integration, laying a foundation for further research on the reconstruction of skull defects.

VEGF-Loaded Heparinised Gelatine-Hydroxyapatite-Tricalcium Phosphate Scaffold Accelerates Bone Regeneration via Enhancing Osteogenesis-Angiogenesis Coupling

Background: Bone tissue defect, one of the common orthopaedicdiseases, is traumatizing and affects patient’s lifestyle. Although autologous and xenograft bone transplantations are performed in bone tissue engineering, clinical development of bone transplantation is limited because ofvarious factors, such as varying degrees of immune rejection, lack of bone sources, and secondary damage to bone harvesting. Methods: We synthesised a heparinised gelatine-hydroxyapatite-tricalcium phosphate (HG-HA-TCP) scaffold loaded with sustained-release vascular endothelial growth factor (VEGF) analysed their structure, mechanical properties, and biocompatibility. Additionally, the effects of HG-HA-TCP (VEGF) scaffolds on osteogenic differentiation and vascularisation of stem cells from human exfoliated deciduous teeth (SHED) in vitro and bone regeneration in vivo were investigated. Results: HG-HA-TCP scaffold possessed good pore structure, mechanical properties, and biocompatibility. HG-HA-TCP scaffold loaded with VEGF could effectively promote SHED proliferation, migration, and adhesion. Moreover, HG-HA-TCP (VEGF) scaffold increased the expression of osteogenesis- and angiogenesis-related genes and promoted osteogenic differentiation and vascularisation in cells. In vivo results demonstrated that VEGF-loaded HG-HA-TCP scaffold improved new bone regeneration and enhanced bone mineral density, revealed byhistological, micro-CT and histochemical straining analyses. Osteogenic and angiogenic abilities of the three biological scaffolds wereranked as follows: HG-HA-TCP (VEGF) > G-HA-TCP (VEGF) > G-HA-TCP. Conclusion: HG-HA-TCP (VEGF) scaffold with good biocompatibility could create an encouraging osteogenic microenvironment that could accelerate vessel formation and osteogenesis, providing an effective scaffold for bone tissue engineering and developing new clinical treatment strategies for bone tissue defects.

Preparation of Magnetic Activated Carbon by Activation and Modification of Char Derived from Co-Pyrolysis of Lignite and Biomass and Its Adsorption of Heavy-Metal-Containing Wastewater

Adsorption with activated carbon (AC) is an important method for the treatment of heavy metal wastewater, but there are still certain challenges in the separation and reuse of activated carbon. The preparation of magnetic activated carbon (MAC) by modifying AC is one of the effective means to realize the separation of AC from solution after the adsorption process. In this work, lignite and poplar leaves were used as raw materials for co-pyrolysis, and the co-pyrolysis char was activated and modified to prepare MAC. The structure and properties were characterized by VSM, N2 adsorption, SEM, XRD, and FT-IR. At the same time, the adsorption performance of MAC on wastewater containing Pb and Cd ions was studied. The results show that the prepared MAC contains Fe3O4, and the saturation magnetization (Ms) of the MAC is 13.83 emu/g; the specific surface area of the MAC is 805.86 m2/g, and the micropore volume is 0.23 cm3/g; the MAC exhibited a good porous structure. When the pH value of the solution was 5, the adsorption time was 120 min, the dosage of MAC was 4 g/L, the initial concentration of Pb ion solution was 50 mg/L, and that of Cd ion solution was 25 mg/L, and the adsorption temperature was 30 °C, the adsorption efficiency of Pb, Cd ions were 84.40 and 78.80%, respectively, and the adsorption capacities were 10.55 and 4.93 mg/g, respectively. The adsorption of Pb and Cd ions by MAC conforms to the Langmuir adsorption model, which is a monolayer adsorption. The adsorption process is mainly chemical adsorption, which can be better described by the pseudo-second-order model. The adsorption thermodynamic analysis showed that the adsorption of Pb and Cd ions by MAC was a spontaneous reaction, and the higher the temperature, the stronger the spontaneity.

Study on the cyclic adsorption performance of biomass composite membrane for Hg(Ⅱ)

ABSTRACT Salix psammophila wood flour /polyvinyl alcohol hydrogel composite membrane (SPPM) with high adsorption capacity and good cycle adsorption performance was prepared by wet spinning technology. The SPPM was characterized by the scanning electron microscope (SEM), specific surface area test (BET), energy dispersive spectrum (EDS) thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectroscopy (XPS). The results showed that the surface of SPPM is rough and porous, with good pore structure and thermal stability, and mercury ions (Hg(II)) have been successfully adsorbed on SPPM. At the same time, the effects of adsorption conditions (Hg(Ⅱ) initial concentration, pH, adsorption time, and temperature) on the adsorption performance of SPPM were studied. Results from the adsorption experiment showed that the adsorption capacity of SPPM for Hg(Ⅱ) can reach 426 mg/g. After four adsorption and desorption experiments, the adsorption capacity can reach 375 mg/g, which indicates that SPPM has good cycle adsorption performance. The adsorption kinetics were better described by the Pseudo-second-order kinetic, and their adsorption isotherms were fitted for the Langmuir model. The obtained results showed that SPPM is an available, economical adsorbent and was found suitable for removing Hg(II) from an aqueous solution.

Selective adsorption of trace gaseous ammonia from air by a sulfonic acid-modified silica xerogel: Preparation, characterization and performance

The toxic and corrosive gaseous ammonia (NH3) poses serious environmental and health risks. However, removal of low concentration NH3 from air remains challenging. In this work, a SO3H-modified silica xerogel (MPTS-X) with good porous structure stability and abundant Bronsted acid sites was fabricated, and its physicochemical properties and adsorption performance for NH3 were systematically investigated. Static adsorption experiments showed the MPTS-1.0 had high NH3 adsorption capacity of 4.02 mmol⋅g−1 at 0.1 bar and 7.00 mmol⋅g−1 at 1.0 bar, which was much higher than that of MPTS-0 (3.19 and 1.95 mmol⋅g−1). Langmuir-Freundlich isotherm model fitted the experimental data of NH3 adsorption well, implying that the MPTS-1.0 surface is not homogeneous and there are different adsorption sites, which was further confirmed by temperature programmed desorption spectrum analysis. According to IAST calculation, the adsorption selectivity of MPTS-1.0 for NH3/N2 (1: 9) and NH3/CO2 (1: 1) was 6175 and 165 at 1.0 bar, respectively, indicating the MPTS-1.0 has excellent adsorption selectivity. Dynamic adsorption experiments and field test demonstrated the MPTS-1.0 could quickly capture trace NH3, even if the initial concentration is as low as 2 ppm. Successive adsorption–desorption experiments demonstrated the MPTS-1.0 had good regenerability. In-situ infrared spectroscopy analyses indicated NH3 adsorption on the MPTS-1.0 was mainly due to hydrogen bonding interaction and proton transfer to form Si-OH…NH3 and -SO3-NH4+, respectively. NH3 molecules bound firmly to acidic sites on the xerogel surface, which reduced re-release risk. This work may provide a feasible way to develop promising adsorbents for the removal of gaseous ammonia from air.

Fabrication of Precursor by Consolidating Aluminum Alloy Powder Using Friction Stir Welding and Its Foaming

In this study, we fabricated a precursor by FSW using ADC12 (Al-Si-Cu alloy) powder and foamed the obtained precursor by optical heating to fabricate the porous aluminum (Al). If ADC12 powder can be used for fabricating the precursor, it is expected that Al waste materials from the manufacturing of industrial products, such as Al cutting scraps, can be used as recycled Al chips, with which the cost of porous Al manufacturing can be reduced. The results demonstrated that ADC12 powder can be consolidated as well as the blowing agent (titanium hydride) and stabilization agent (alumina) powders can be mixed into the consolidated ADC12 by FSW to fabricate precursors at the tool traversing speed v = 10–50 mm/min. In addition, the obtained precursor can be foamed by optical heating. It was also found that the precursor with fewer cracks and defects can be obtained at v = 10, 20, and 30 mm/min versus at v = 40 and 50 mm/min. As a result, porous Al with relatively good pore structures was obtained at v = 10–30 mm/min.

Synthesis of diphenylamine by condensation of aniline catalyzed by microporous-mesoporous composite solid acid nanoreactor

Microporous zeolite has regular pores, good surface properties and strong thermal and hydrothermal stability, but the adsorption and diffusion of macromolecules are limited by small and narrow pores, and the active sites of pores are difficult to use effectively. Mesoporous materials have good pore structure, but poor thermal and hydrothermal stability and weak acidity. In order to overcome the structural defects of single channel catalyst, a series of β zeolite and activated clay composite solid acid catalysts were prepared in this paper. X-ray diffraction and N2 physical adsorption-desorption showed that the composite catalyst has a microporous-mesoporous composite structure. The synthesis of diphenylamine by aniline condensation proved that the composite catalyst can be used as nanoreactor to promote the reaction. Combined with pyridine adsorption infrared spectroscopy, thermogravimetry, scanning electron microscope and kinetic analysis, the catalytic mechanism of microporous-msoporous composite solid acid nanoreactor was explored.