High Brunauer Emmett Teller Surface Area Research Articles

Oxygen‐Rich Porous Organic Polymer for Thermal Energy Storage

Oxygen atoms have been widely used in porous organic polymers, which has attracted much attention from researchers. Herein, porous organic polymer with high oxygen content is synthesized with oxygen‐rich monomer as construction unit and anhydrous aluminum chloride as catalyst; then phase‐change materials (PCMs) composites are prepared by self‐adsorption method. The pore properties of the oxygen‐rich porous organic polymer are characterized by nitrogen absorption and desorption method. The properties of the PCM composites are characterized by scanning electron microscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The results show that the oxygen‐rich porous organic polymer has high Brunauer–Emmett–Teller surface area (465 m2 g−1) and excellent thermal stability. The PCM composites possess high encapsulation rate (50.6 wt%) and latent heat (124.7 kJ g−1). After several thermal cycles, the thermal properties of all PCM composites are almost unchanged, and no leakage phenomenon is found. It can be seen that oxygen‐rich porous polymers have potential applications in PCM adsorption and thermal energy storage.

Acetaminophen removal using porous activated carbon derived from corn cob: optimization and mass transfer modelling

AbstractBACKGROUNDAcetaminophen, also known as paracetamol, has been notably detected in aquatic environments, including wastewater, surface water and drinking water, causing significant concern within the scientific and environmental research communities. This study focuses on two main objectives: (i) optimizing corn cob‐based activated carbon (CCAC) through response surface methodology for the adsorption of acetaminophen and (ii) simulating the acetaminophen adsorption process using the polymath mass transfer (PMT) model.RESULTSThe optimized CCAC was prepared via physiochemical activation under microwave radiation (265 W power) for 6 min, with a KOH impregnation ratio of 0.50 g g−1. This process resulted in a high Brunauer–Emmett–Teller surface area of 976.29 m2 g−1, accompanied by a corresponding pore volume of 0.39 cm3 g−1 and a pore diameter of 2.38 nm. The adsorption study, employing differential initial concentrations (ranging from 5 to 30 mg L−1) of acetaminophen, revealed a substantial adsorption capacity of 22.43 mg g−1 (74.77%) at 30 °C and 20.74 mg g−1 (69.13%) at pH 6. The PMT model indicated an adsorption capacity (Qm) of 21.14 mg g−1, with an error of 5.75%, demonstrating high precision compared to the experimental result. Additionally, the calculated R2 values equal to or above 0.90 indicated strong agreement between the PMT model and experimental data.CONCLUSIONThus, applying the PMT model proved to be economical and cost‐effective, providing accurate predictions on surface area during adsorption performance compared to the time‐consuming and costly process of conducting characterizations. © 2024 Society of Chemical Industry (SCI).

Preparation of self-standing ultra-thin three-dimensional covalent organic frameworks by interfacial polymerization for dye separation

Three-dimensional covalent organic frameworks (3D COFs) have garnered considerable attention in the adsorption of small molecules owing to their unique 3D pore structure and easily modifiable functional group sites. However, most 3D COFs exhibit lattice interpenetration, making the membrane fabrication process difficult. Most 3D COFs are prepared as powders using solvothermal methods, which severely limits their application in material separation. Therefore, self-supporting 3D COFs membranes were fabricated using room-temperature interfacial polymerization, a low-energy method. Traditional alkane/water interfacial polymerization methods have disadvantages such as poor water solubility of the monomer, volatile solvents, and low crystallinity. Herein, an imine-linked, self-standing, 3D COFs membrane with an ultrathin layer was engineered at the alkane/ionic liquid interface. Owing to the improved crystalline structure, which exposed a large number of imine-linked sites within a 3D pore channel, the constructed 3D COFs membrane exhibited a high Brunauer–Emmett–Teller surface area of 1061.4 m2·g−1 and high water flux of approximately 76 L·m−2 h−1 bar−1 and demonstrated excellent rejection rates of 97.76% and 95.36% for two cationic dyes, rhodamine B and methylene blue, respectively. The membrane exhibited high rejection rates after seven testing cycles. This study reveals the great potential of self-standing 3D COFs membranes as dye separation.

Creating high-affinity binding sites for efficient CO2 and iodine vapor uptake through direct synthesis of novel triazine-based covalent organic polymers

Two types of triazine-based covalent organic polymers were successfully constructed through a one-pot and catalyst-free polycondensation approach. More specifically, two kinds of aromatic aldehyde containing different hydroxyl content named terephthalaldehyde and 2, 4, 6-trihydroxyisophthalaldehyde were selected and the derived polymers (denoted as POPs-1 and POPs-2) with large Brunauer-Emmett-Teller (BET) surface areas (> 360 m2/g), high total pore volume (> 0.47 m3/g), good stability and different heteroatoms (such as N and O) contents were prepared. Interestingly, POPs-1 featuring high BET surface area and N content (up to 34.83 %) exhibited excellent iodine vapor uptake of 441 wt% at 348 K/1.0 bar, POPs-2 with high O content (up to 25.83 %) showed better CO2 adsorption capacity (91.8 mg/g) at 273 K/1.0 bar and higher isosteric heat of adsorption (up to 85.0 kJ/mol) than that of POPs-1. This value of the isosteric heat is the highest value reported to date for porous organic polymers. This excellent adsorption performance was resulted either from the large BET surface area or high heteroatoms (N and O) contents of the porous adsorbents. The study offer an alternative route to develop high-performance porous adsorbents to capture carbon dioxide and iodine.

Synthesizing Interpenetrated Triazine‐based Covalent Organic Frameworks from CO2

AbstractCrystalline triazine‐based covalent organic frameworks (COFs) are aromatic nitrogen‐rich porous materials. COFs typically show high thermal/chemical stability, and are promising for energy applications, but often require harsh synthesis conditions and suffer from low crystallinity. In this work, we propose an environmentally friendly route for the synthesis of crystalline COFs from CO2 molecules as a precursor. The mass ratio of CO2 conversion into COFs formula unit reaches 46.3 %. The synthesis consists of two steps; preparation of 1,4‐piperazinedicarboxaldehyde from CO2 and piperazine, and condensation of the dicarboxaldehyde and melamine to construct the framework. The CO2‐derived COF has a 3‐fold interpenetrated structure of 2D layers determined by powder X‐ray diffraction, high‐resolution transmission electron microscopy, and select‐area electron diffraction. The structure shows a high Brunauer–Emmett–Teller surface area of 945 m2 g−1 and high stability against strong acid (6 M HCl), base (6 M NaOH), and boiling water over 24 hours. Post‐modification of the framework with oxone has been demonstrated to modulate hydrophilicity, and it exhibits proton conductivity of 2.5×10−2 S cm−1 at 85 °C, 95 % of relative humidity.

Triphenylamine–Anthracene-Based Conjugated Microporous Polymers for the Detection and Photocatalytic Degradation of Organic Micropollutants

Triphenylamine (TPA)–anthracene (AN)-based conjugated microporous polymers (CMPs), namely PTPA-AN-9,10 and PTPA-AN-2,6, were synthesized by the Suzuki–Miyaura cross-coupling reaction of tris(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-amine with 9,10-dibromoanthracene and 2,6-dibromoanthracene, respectively. The as-synthesized polymers exhibited cauliflower-like nanoscale morphology , high Brunauer–Emmett–Teller surface area of 362 m2/g, and thermal stability up to 458 °C in the case of PTPA-AN-2,6. Interestingly, PTPA-AN-9,10 showed bright cyan fluorescence in tetrahydrofuran dispersion and exhibited fluorescence-based sensing of various nitroaromatics, where 2,4,6-trinitrophenol exhibited the lowest limit of detection of 34 μM and the highest Stern–Volmer constant (KSV) of 5.8 × 103 L mol–1. On the other hand, PTPA-AN-2,6 showed efficient photocatalytic reduction of various nitroaromatic micropollutants such as p-nitrophenol (p-NP) (k = 0.164 min–1 and turnover frequency (TOF) = 0.769 h–1) and degradation of Congo red from water with ultrafast kinetics (k = 0.047 min–1 and TOF = 0.024 h–1) which are much better than most of the previously reported CMPs. These polymers were recovered using simple filtration and were recycled four to five times without losing their catalytic efficiency significantly for p-NP reduction as well as dye degradation. In general, TPA-based CMPs have been used as efficient multitasking materials for the sensing of nitroaromatic micropollutants and photocatalytic degradation of Congo red dye as well as p-NP to its value-added product p-aminophenol.

Non‐Interpenetrated 3D Covalent Organic Framework with Dia Topology for Au Ions Capture

AbstractThe 3D covalent organic frameworks (COFs) have attracted considerable attention owing to their unique structural characteristics. However, most of 3D COFs have interpenetration phenomena, which will result in decreased surface area and porosities, and thus limited their applications in molecular/gas capture. Developing 3D COFs with non‐fold interpenetration is challenging but significant because of the existence of non‐covalent interactions between the adjacent nets. Herein, a new 3D COF (BMTA‐TFPM‐COF) with dia topology and non‐fold interpenetration for Au ion capture is first demonstrated. The constructed COF exhibits a high Brunauer–Emmett–Teller surface area of 1924 m2 g−1, with the pore volume of 1.85 cm3 g−1. The high surface area and abundant cavities as well as the abundant exposed CN linkages due to the non‐interpenetration enable to absorb Au3+ with high capacity (570.18 mg g−1), selectivity (99.5%), and efficiency (68.3% adsorption of maximum capacity in 5 min). This work provides a new strategy to design 3D COFs for ion capture.

New Porous Carbon Material Derived from Carbon Microspheres Assembled in Hollow Carbon Spheres and Its Application to Toluene Adsorption.

In this paper, a new porous carbon material adsorbent was prepared using carbon microspheres assembled in hollow carbon spheres (HCS) with a hydrothermal method. Transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy were used to characterize the adsorbents. It was found that the diameter of carbon microspheres derived from 0.1 mol/L glucose was about 130 nm, which could be inserted inside HCS (pore size was 370-450 nm). The increase in glucose concentration would promote the diameter of carbon microspheres (CSs), and coarse CSs could not be loaded in the mesopores or macropores of HCS. Thus, the C0.1@HCS adsorbent had the highest Brunauer-Emmett-Teller surface area (1945 m2/g) and total pore volume (1.627 cm3/g). At the same time, C0.1@HCS posed a suitable ratio of micropores and mesopores, which could provide adsorption sites and volatile organic compound diffusion channels. Moreover, oxygen-containing functional groups -OH and C═O in CSs were also introduced into HCS, and the adsorption capacity and regenerability performance of the adsorbents were improved. The dynamic adsorption capacity of C0.1@HCS for toluene reached 813 mg/g, and the Bangham model was more suitable for describing the toluene adsorption process. The adsorption capacity was stably kept above 770 mg/g after eight adsorption-desorption cycles.

One-pot facile synthesis of hexagonal Bi2Te3 nanosheets and its novel nanocomposites: Characterization, anticancer, antibacterial, and antioxidant activities

Bismuth Telluride (Bi2Te3) layered structure results in extraordinary features in diagnostic and therapeutic applications. However, Bi2Te3 synthesis with reliable stability and biocompatibility in biological systems was the major challenge that limited its biological application. Herein, reduced graphene oxide (RGO) or graphitic carbon nitride (CN) nanosheets were incorporated into Bi2Te3 matrix to improve exfoliation. Bi2Te3 nanoparticles (NPs) and its novel nanocomposites (NCs): CN@Bi2Te3 and CN-RGO@Bi2Te3 were solvothermally synthesized, physiochemically characterized and assessed for their anticancer, antioxidant, and antibacterial activities. X-ray diffraction depicted Bi2Te3 rhombohedral lattice structure. Fourier-transform infrared and Raman spectra confirmed NC formation. Scanning and transmission electron microscopy revealed 13 nm thickness and 400–600 nm diameter of hexagonal, binary, and ternary nanosheets of Bi2Te3-NPs/NCs. Energy dispersive X-ray Spectroscopy revealed the presence of Bi, Te, and carbon atoms in the tested NPs with negatively charged surfaces as depicted by zeta sizer. CN-RGO@Bi2Te3-NC displayed the smallest nanodiameter (359.7 nm) with the highest Brunauer–Emmett–Teller surface area and antiproliferative activity against MCF-7, HepG2 and Caco-2. Bi2Te3-NPs had the greatest scavenging activity (96.13 ± 0.4%) compared to the NCs. The NPs inhibitory activity was greater against Gram-negative bacteria than that of Gram-positive bacteria. Integration of RGO and CN with Bi2Te3-NPs enhanced their physicochemical properties and therapeutic activities giving rise to their promising capacity for future biomedical applications.

Confinement effect and efficient adsorption of furfural onto ZIF‐8‐derived microporous carbon

AbstractBACKGROUNDThe separation of furfural from a low‐concentration multicomponent and acid‐containing aqueous solution is a highly demanding process; traditional distillation requires an excessive amount of energy. Herein, we demonstrated ZIF‐8‐derived microporous carbon (C) as a promising adsorbent for the separation of furfural using adsorption isotherms, dynamic column adsorption, adsorption kinetics and desorption studies.RESULTSIn the competitive adsorption kinetics experiments with a furfural/acetic acid concentration of 50/20 g L−1, the acetic acid adsorbed in the micropores of NCZIF‐81000C‐800A gradually was replaced by furfural, whereas the amount of acetic acid in the mesopores of NCZIF‐8800C‐800A slowly increased. In addition, the micropores of NCZIF‐81000C‐800A exhibited highly efficient and fast adsorption characteristics toward furfural over a wide furfural/acetic acid concentration range (0–50/0–20 g L−1) with the furfural adsorption capacity reaching an adsorption equilibrium within 10 min. The results show that the high Brunauer–Emmett–Teller surface area of NCZIF‐81000C‐800A is responsible for the high furfural adsorption capacity (1205.3 mg g−1) and the confined microporous structure can strengthen the π–π interactions between porous C and furfural, thereby enhancing the selectivity of furfural/acetic acid (61.4) in the furfural/acetic acid (50/20 g L−1) dynamic column adsorption system. Meanwhile, the desorption ratio of furfural in the dynamic desorption system reached as high as 98.6%.CONCLUSIONThe unique micropore‐confinement effect and excellent adsorption behavior make NCZIF‐81000C‐800A an efficient adsorbent for furfural in the furfural–acetic acid system. © 2023 Society of Chemical Industry (SCI).

Regulating the Pt-MnO2 Interaction and Interface for Room Temperature Formaldehyde Oxidation.

Formaldehyde (HCHO) is a hazardous pollutant in indoor space for humans because of its carcinogenicity. Removing the pollutant by MnO2-based catalysts is of great interest because of their high oxidation performance at room temperature. In this work, we regulate the Pt-MnO2 (MnO2 = manganese oxide) interaction and interface by embedding Pt in MnO2 (Pt-in-MnO2) and by dispersing Pt on MnO2 (Pt-on-MnO2) for HCHO oxidation over Pt-MnO2 catalysts with trace Pt loading of 0.01 wt %. In comparison to the Pt-in-MnO2 catalyst, the Pt-on-MnO2 catalyst has a higher Brunauer-Emmett-Teller surface area, a more active lattice oxygen, more oxygen vacancy activating more dioxygen molecules, more exposed Pt atoms, and noninternal diffusion of mass transfer, which contribute to the higher HCHO oxidation performance. The HCHO oxidation performance is stable over the Pt-MnO2 catalysts under high space velocity and high moisture humidity conditions, showing great potential for practical applications. This work demonstrates a more effective Pt-dispersed MnO2 catalyst than Pt-embedded MnO2 catalyst for HCHO oxidation, providing universally important guidance for metal-support interaction and interface regulation for oxidation reactions.

MoS2-NiO nanocomposite for H2S sensing at room temperature.

The layered 2-D materials, such as molybdenum disulfide (MoS2), are among the most promising candidates for detecting H2S gas at very low concentrations. Herein, we have designed a series of novel nanocomposites consisting of MoS2 and NiO. These materials were synthesized via a simple hydrothermal method. The microstructure and morphology of nanocomposites were studied using different characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). These nanocomposites were used as gas sensors, and the highest response (6.3) towards 10 ppm H2S was detected by the MNO-10 gas sensor among all the tested sensors. The response value (Rg/Ra) was almost three times that of pure NiO (Rg/Ra = 2). Besides, the MNO-10 sensor exposed good selectivity, short response/recovery time (50/20 s), long-term stability (28 days), reproducibility (6 cycles), and a low detection limit (2 ppm) towards H2S gas at RT. The excellent performance of MNO-10 may be attributed to some features of MoS2, such as a layered structure, higher BET surface area, higher active sites, and a synergistic effect between MoS2 and NiO. This simple fabrication sensor throws a novel idea for detecting H2S gas.

Co-Based Catalysts Supported on Ceria with Different Shape Structures for Hydrodeoxygenation of Guaiacol

CeO2 with three different morphologies of nanorods (CeO2-r), particles (CeO2-p), and cubes (CeO2-c) was prepared, and the guaiacol hydrodeoxygenation over their corresponding Co-based catalysts was performed at 160–220 °C, 2 MPa, a H2 flow rate of 80 mL/min, and a weight hourly space velocity of 0.7 h–1. Compared with Co/CeO2-p and Co/CeO2-c, Co/CeO2-r has smaller Co particle sizes, a higher Brunauer–Emmett–Teller surface area, and larger amount of Co active centers, oxygen vacancies, and weak acid sites. These better physicochemical properties for Co/CeO2-r provide more Co active sites for guaiacol hydrodeoxygenation, favor the adsorption and activation of guaiacol, and contribute to the cleavage of C–O. Therefore, Co/CeO2-r presents a maximum guaiacol conversion of 97.1% and the highest yield of cyclohexanol of 91.7% among these catalysts. The result shows that the shape structure of CeO2 has an important influence on the guaiacol hydrodeoxygenation performance over its corresponding catalysts.

Comparative Study of the Structural, Mechanical and Electrochemical Properties of Polyacrylonitrile (PAN)-Based Polypyrrole (PPy) and Polyvinylidene Fluoride (PVDF) Electrospun Nanofibers

In this study, polyacrylonitrile (PAN)-based polypyrrole (PPy) and polyvinylidene fluoride (PVDF) nanofibers (PAN/PPy, PAN/PVDF and PAN/PPy/PVDF) were produced by an electrospinning method and their mechanical and electrochemical properties were compared, resulting in obtaining a composite material that had high mechanical strength and electrical conductivity at the same time. The morphological, structural, mechanical and electrochemical performance of the nanofibers were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that beadless and smooth nanofiber formation was achieved for all of the PAN/PPy, PAN/PPy/PVDF and PAN/PVDF combinations. PAN/PPy/PVDF, containing 80 wt% PAN 10 wt% PPy and 10 wt% PVDF, had the highest BET surface area and the smallest pore size. In terms of mechanical properties, PAN/PPy/PVDF nanofibers (80 wt% PAN, 10 wt% PPy, 10 wt% PVDF) also showed the highest Young Modulus, 36.82 MPa, while that of the PAN/PPy nanofibers was the lowest. Therefore, in terms of physical and mechanical properties, the PAN/PPy/PVDF combination was favored. However, in terms of the electrochemical properties, CV and EIS data showed that the PAN/PPy nanofibers had the highest electrical conductivity among the PAN-based nanofibers.

Superior Iodine Uptake Capacity Enabled by an Open Metal-Sulfide Framework Composed of Three Types of Active Sites

Superior Iodine Uptake Capacity Enabled by an Open Metal-Sulfide Framework Composed of Three Types of Active Sites

Studies on high performance rubber composites by incorporating titanium dioxide particles with different surface area and particle size

In this work, we incorporate titanium dioxide (TiO2) particles as fillers into room temperature vulcanized silicone rubber (RTV-SR) and fabricated the RTV-SR/TiO2 composites. Herein, the effect of various surface areas of TiO2 particles on the mechanical properties of RTV-SR/TiO2 composites was investigated. The particle size of different types of TiO2 particles (147 nm, 34 nm, and 29 nm) was measured by using scanning electron microscopy (SEM), whereas the Brunauer–Emmett–Teller (BET) surface area was measured through adsorption-desorption isotherms as 3, 50, and 145 m2/g, respectively. TiO2 particles reinforced RTV-SR composites were prepared by solution mixing method. TiO2 particles with smaller particle sizes and high BET surface area exhibited higher mechanical properties. The compressive moduli were obtained as 2.2 MPa for a virgin sample and increased to 2.6 MPa, 2.8 MPa and 3.24 MPa for 3, 50, and 145 m2/g samples respectively at 6 phr filler loading. Similarly, the fracture strain of the composite was 117% for a virgin sample and changed to 94%, 130%, and 205% for 3, 50, and 145 m2/g samples, respectively, at 8 phr filler loading. The surface area and particle size of the fillers showed significant effect on mechanical properties of the composites, but no significant effect was observed on the energy harvesting values of RTV-SR/TiO2 composites.

Development of Co–Nb–CeO2 Catalyst for Hydrogen Production from Waste-Derived Synthesis Gas Using Techno-Economic and Environmental Assessment

A comparative study to obtain a cost-competitive catalyst was performed to produce hydrogen via the high temperature water gas shift (WGS) reaction using synthesis gas (syngas) derived from waste. First, several selected active metals on Nb–CeO2 support and preparation methods were applied to prepare highly active and stable catalysts under severe reaction conditions. Various characterization methods were employed to understand the correlation between catalytic activity and physicochemical properties of the prepared catalysts. Among the Me–Nb–CeO2 (Me = Co, Cu, Fe, and Zn) catalysts, Co–Nb–CeO2 showed the highest activity at a high gas hourly space velocity of 315,282 mL·g–1·h–1 (temperature = 500 °C, XCO ≈ 84%). This was attributed to the high Brunauer–Emmett–Teller surface area and oxygen storage capacity of the Co–Nb–CeO2 catalyst. In addition, to investigate the effect of preparation method, various methods, including coprecipitation, incipient wetness impregnation, sol–gel, and hydrothermal methods, were applied for the synthesis of the Co–Nb–CeO2 catalyst. The Co–Nb–CeO2 catalyst prepared using the coprecipitation method exhibited high activity without significant deactivation for 60 h. This was attributed to the high oxygen storage capacity and intimate interaction between Co and the Nb–CeO2 support. Finally, techno-economic analysis and environmental impact assessment were performed for the Co–Nb–CeO2 catalysts, prepared by different preparation methods to identify the most promising catalyst for the production of hydrogen using the syngas derived from waste. By comparison with a commercial catalyst, it was shown that Co–Nb–CeO2 synthesized using coprecipitation is a promising, cost-effective, and eco-friendly catalyst with high activity.

Synthesis and Characterization of a Crystalline Imine-Based Covalent Organic Framework with Triazine Node and Biphenyl Linker and Its Fluorinated Derivate for CO2/CH4 Separation.

A catalyst-free Schiff base reaction was applied to synthesize two imine-linked covalent organic frameworks (COFs). The condensation reaction of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) with 4,4′-biphenyldicarboxaldehyde led to the structure of HHU-COF-1 (HHU = Heinrich-Heine University). The fluorinated analog HHU-COF-2 was obtained with 2,2′,3,3′,5,5′,6,6′-octafluoro-4,4′-biphenyldicarboxaldehyde. Solid-state NMR, infrared spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis confirmed the successful formation of the two network structures. The crystalline materials are characterized by high Brunauer–Emmett–Teller surface areas of 2352 m2/g for HHU-COF-1 and 1356 m2/g for HHU-COF-2. The products of a larger-scale synthesis were applied to prepare mixed-matrix membranes (MMMs) with the polymer Matrimid. CO2/CH4 permeation tests revealed a moderate increase in CO2 permeability at constant selectivity for HHU-COF-1 as a dispersed phase, whereas application of the fluorinated COF led to a CO2/CH4 selectivity increase from 42 for the pure Matrimid membrane to 51 for 8 wt% of HHU-COF-2 and a permeability increase from 6.8 to 13.0 Barrer for the 24 wt% MMM.

Effect of ilmenite properties on synthetic rutile quality

Ilmenite (TiO2 > 52%) can be upgraded to synthetic rutile (TiO2 > 88%) using a reduction and leaching process. Australian ilmenites (FeTiO3) contain variable amounts of titanium dioxide, iron oxide and other impurities. Ilmenites from different deposits can have different physical and chemical properties that affect ilmenite reduction and the final TiO2 content in synthetic rutile (SR). The main aim of this study was to characterise feed ilmenites using a wide range of traditional and advanced analytical techniques and to determine the effects of feed properties on the quality of the SR. Three different ilmenite samples were upgraded to SR using a comparable ilmenite to coal ratio, heating rate, reduction temperature, holding time, cooling temperature and acid leaching parameters. Differential scanning calorimetry, thermogravimetric analysis, Brunauer–Emmett–Teller (BET) surface analysis and sizing analysis data indicated a difference in physical and surface properties among the samples. Head samples had a TiO2 content between 60% and 65% and Fe2O3 content between 25% and 34%. XRF assay by size data confirmed a variation in the content of TiO2, Fe2O3 and impurities among different size fractions. XRD phase analysis indicated the samples were composed of ilmenite, pseudorutile and rutile. SEM morphology studies revealed that ilmenite particle shapes were sub-angular, sub-rounded or rounded. The study found a linear relationship between the metallisation as a result of processing and feed BET surface area. Feed ilmenites with higher BET surface area and fewer impurities resulted in higher SR quality.

Adsorption Characteristics of Chitosan-Modified Bamboo Biochar in Cd(II) Contaminated Water

The purpose of this study was to fabricate a low-cost and eco-friendly adsorbent using bamboo biochar (BB), a kind of charcoal composed of high Brunauer–Emmett–Teller surface area and variety of functional groups, and chitosan as substrates for remediation of Cd(II) in Cd(II) contaminated water and characterized the functional group characteristics, surface morphology, and Cd(II) adsorption effect using the Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS). Results showed that chitosan-modified bamboo biochar (CBB) provided more active adsorption sites (such as –NH2, –COOH, –OH, and C=O) on the surface to enhance the Cd(II) removal efficiency in Cd(II) contaminated wastewater. Meanwhile, the optimal pH, contact time, and dose of CBB on the Cd(II) removal efficiency are 7, 120 min, and 600 mg, respectively. In addition, the adsorption isotherm results revealed that the possible adsorption mechanisms might include surface adsorption, electrostatic adsorption, and ion exchanges. Furthermore, the maximum adsorption capacity (Qm) values predicted from the Langmuir model were 37.74 and 93.46 mg/g for BB and CBB, respectively, also indicating a potential application of CBB in practical wastewater. Desorption and regeneration of CBB were attained simultaneously and the results showed that even after five cycles of adsorption-elution, the adsorption and desorption of CBB exhibited a slight decline and still reached at 71.70% and 65.92%. Results from this study would provide a reference to functionalized CBB for Cd(II) adsorption in contaminated water.