BET Surface Research Articles

Unveiling the Activity-Electrochemically Active Surface Area Relationship in PGM-Free Oxyphosphide OER Electrocatalysts for Alkaline Water Electrolysis

The oxygen evolution reaction (OER) plays a pivotal role in various electrochemical processes, from water splitting to CO2 electroreduction and metal-air batteries. However, the sluggish kinetics of OER, involving multi-electron transfer, necessitate the development of catalysts with high activity and stability. While platinum group metal (PGM) catalysts like IrO2 and RuO2 exhibit high OER activity in proton exchange membrane (PEM) water electrolysis, their cost hinders widespread adoption. Anion Exchange Membrane Water Electrolysis (AEMWE) emerges as a promising technology with the potential to be both cost-effective and sustainable for hydrogen production. It relies on PGM-free OER catalysts, bridging the gap and merging the strengths of PEM and traditional alkaline electrolysis systems Transition metal (TM) oxides, layered double hydroxides, and oxyphosphides, particularly those incorporating Ni, Fe, and Co, emerge as promising OER catalysts for alkaline water electrolysis. Yet, comparing different catalysts remains challenging due to varied testing protocols that influence reported performances, often referenced to geometric surface area. Herein, we address this challenge by evaluating the intrinsic activity and electrochemically active surface area (ECSA) of PGM-free OER catalysts. Employing a colloidal synthesis approach, TM catalysts were synthesized and tested for OER activity and durability in 1 M KOH. Transmission electron microscopy (TEM) imaging revealed a unique porous structure surrounding a metallic core.To estimate the ECSA, cyclic voltammograms were recorded at various scan rates in a non-Faradaic region. The double layer capacitance (Cdl) was evaluated from the slope of current versus scan rate, and a specific capacitance of 40 μF cm-2 was used to calculate the ECSA. [1-4]Preliminary results demonstrate a direct correlation between OER activity and ECSA. The correlation between the BET surface and OER activity was also studied.AcknowledgmentsThis work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). Argonne is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, under Contract DE-AC-02-06CH11357. 1. McCrory, CCL; Jung, S; Peters, JC; Jaramillo, TF. Benchmarking Heterogeneous Electrocatalysts for the Oxygen Evolution Reaction. J. Am. Chem. Soc. 2013, 135, 16977–16987.2. Sarkar R, Farghaly AA, Arachchige IU. Oxidative Self-Assembly of Au/Ag/Pt Alloy Nanoparticles into High-Surface Area, Mesoporous, and Conductive Aerogels for Methanol Electro-oxidation. Chemistry of Materials. 2022, 34(13), 5874-87.3. Khalafallah D, Farghaly AA, Ouyang C, Huang W, Hong Z. Atomically dispersed Pt single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis. Journal of Power Sources. 2023, 558, 232563.4. Onajah S, Sarkar R, Islam MS, Lalley M, Khan K, Demir M, Abdelhamid HN, Farghaly AA. Silica‐Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review. The Chemical Record. 2024, e202300234.

High-performance novel ZIF-67 and ZIF-67@MWNTs composite adsorbents for efficient removal of pharmaceutical contaminant from water: Exceptional capacity and excellent reusability

The removal of pharmaceutical waste products like ibuprofen (IBP) from water is very important for the environment and the health of human and aquatic organisms. In the present work, the adsorption of IBP from aqueous solution was investigated by synthesizing novel ZIF-67 and ZIF-67@MWNTs hybrid composite material by incorporating ZIF-67 particles with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWNT). The synthesized ZIF-67 and ZIF-67@MWNTs adsorbents were characterized by the XPS, XRD, SEM, TEM, BET, FTIR, and TGA analysis to examine their physio-chemical properties. The synthesized novel ZIF-67 has a 1743 m2/g BET surface and 0.692 cm3/g total pore volume. The IBP adsorption process including isotherm and kinetic studies as well as the effect of different parameters i.e. pH, initial concentration, time, adsorbents, and their dosage were examined. Among all the synthesized composite materials, the ZIF-67@MWNT-50 mg material showed the highest IBP adsorption capacity of 841 ± 5 mg/g, about 467 ± 5 mg/g more than the ZIF-67 following the Langmuir and pseudo-second-order model. The enhancement in the IBP adsorption is because of the incorporation of COOH-MWNT and the presence of a large number of active binding sites which showed the van der Waal interactions, host–guest interactions, π- π interactions, and H-bonding between the adsorbate and adsorbent. For the detailed study of the IBP adsorption mechanism of ZIF-67, molecular dynamic (MD) simulations were performed. Additionally, the reusability of ZIF-67@MWNT-50 mg material via a simple regeneration method up to five cycles while maintaining about 96 % adsorption capacity of the pristine non-used ZIF-67@MWNT-50 mg material revealed its importance as an effective adsorbent for the adsorptive elimination of different pharmaceutical hazardous materials from water.

Enhanced fluoride removal using montmorillonite clay modified with CoFe2O4 and metal-organic frameworks

The use of modified clays can play an effective role as an effective adsorbent in removing fluoride (Flu) ions from water and aqueous solutions. In the present research, montmorillonite clay (MMt) was modified using CoFe2O4 magnetic particles and Al–Fe fumarate metal-organic framework (Al–Fe Fum) and was utilized as an efficient adsorbent for removing Flu from aqueous solution. The properties of MMt and MMt/CoFe2O4/Al–Fe Fum samples were investigated using different techniques. The results showed that with the modification of MMt using CoFe2O4 magnetic particles and the metal-organic framework of Al–Fe Fum, the BET surface has increased notably from 13.217 to 365.80 m2/g. To investigate the effect of independent variables and their interaction on the efficiency of the Flu adsorption, response surface method-central compound design (RSM-CCD) was served. Based on the results of ANOVA, the F-value and p-value parameters for the desired model were determined to be 783.09 and < 0.0001, respectively, which confirms the success and high ability of the model. The number of R2, adjusted R2, and Predicted R2 for adsorption of Flu ion was determined to be 0.998, 0.997, and 0.995, respectively, which shows that the proposed regression model can describe the process of adsorption and interaction between variables well. Compared to other kinetic models, the pseudo 2nd order kinetic model has a greater ability to describe the Flu adsorption behavior. The R2 parameter value determined that the Freundlich isotherm model has a suitable ability to investigate the isotherm behavior and confirms the effect of heterogeneous surfaces in the process. Generally, the outcomes signified that the MMt and MMt/CoFe2O4/Al–Fe Fum samples can be reused several times in the process of Flu adsorption, while the efficiency is more than 90%.

Characterization and adsorption properties of rectorite/sludge-derived biochar composites for Pb(II) removal

Clay-based adsorbent materials are widely used to remove heavy metal ions from water. In this study, we have fabricated a novel composite material, consisting of rectorite and sludge-derived biochar (REC/SDBC), and characterized its effectiveness in removing lead from water. Our SEM images show that the REC is evenly dispersed on the surface of the SDBC. The composites have a mesoporous structure, and its BET surface is (16.5 m2/g) comparable with that of SDBC but larger than that of REC. We found that the maximum adsorption capacity for Pb(II) was 26.89 mg g−1 for REC/SDBC composites with a REC:SDBC ratio of 3:1, which was achieved within 120 min. This is higher than the adsorption capacities of REC (19.81 mg g−1) and SDBC (23.15 mg g−1) alone. Furthermore, we observed that the adsorption capacity was greater at pH 5.0 compared to other pH values. Our results also indicate that the pseudo-second-order model and the Langmuir isotherm model provide good fits for the rates and isotherms of Pb(II) adsorption onto REC/SDBC composites. The adsorption kinetic constant and the Langmuir adsorption constant were calculated to be 0.0065 g mg−1 min−1 and 0.319 L mg−1, respectively. X-ray photoelectron spectroscopy analysis confirmed that the reaction mechanism is mainly dominated by chemisorption, involving cationic exchange, surface complexation, and surface precipitation. The high adsorption capacity, combined with the cost-effectiveness and environmental-friendly nature of REC/SDBC composites, make them promising candidates for removing heavy metallic elements from wastewater.

Experimental Study and Thermodynamic Analysis of Carbon Dioxide Adsorption onto Activated Carbons Prepared from Biowaste Raw Materials

Nutshells are regarded as cost-effective and abundant raw materials for producing activated carbons (ACs) for CO2 capture, storage, and utilization. The effects of carbonization temperature and thermochemical KOH activation conditions on the porous structure as a BET surface, micropore volume, micropore width, and pore size distribution of ACs prepared from walnut (WNS) and hazelnut (HNS) shells were investigated. As a result, one-step carbonization at 900/800 °C and thermochemical KOH activation with a char/KOH mass ratio of 1:2/1:3 were found to be optimal for preparing ACs from WNS/HNS: WNS-AC-3 and HNS-AC-2, respectively. The textural properties of the WNS/HNS chars and ACs were characterized by low-temperature nitrogen vapor adsorption, XRD, and SEM methods. Dubinin’s theory of volume filling of micropores was used to evaluate the microporosity parameters and to calculate the CO2 adsorption equilibrium over the sub- and supercritical temperatures from 216.4 to 393 K at a pressure up to 10 MPa. The CO2 capture capacities of WNS- and HNS-derived adsorbents reached 5.9/4.1 and 5.4/3.9 mmol/g at 273/293 K under 0.1 MPa pressure, respectively. A discrepancy between the total and delivery volumetric adsorption capacities of the adsorbents was attributed to the strong binding of CO2 molecules with the adsorption sites, which were mainly narrow micropores with a high adsorption potential. The high initial differential heats of CO2 adsorption onto ACs of ~32 kJ/mol confirmed this proposal. The behaviors of thermodynamic functions (enthalpy and entropy) of the adsorption systems were attributed to changes in the state of adsorbed CO2 molecules determined by a balance between attractive and repulsive CO2–CO2 and CO2–AC interactions during the adsorption process. Thus, the chosen route for preparing ACs from the nutshells made it possible to prepare efficient carbon adsorbents with a relatively high CO2 adsorption performance due to a substantial volume of micropores with a size in the range of 0.6–0.7 nm.

Controlled growth of graphene on γ-Al2O3 as highly efficient nanocomposite support of NiMoW catalysts by engineering approaches of chemical vapor deposition technique for hydrotreating of vacuum gas oil

In this study, a novel γ-Al2O3@Graphene-Cu nanocomposite support has been successfully prepared by the CVD method with a mixed gas of methane/hydrogen to improve hydrotreating (HDT) activities further and explore the metals-support interaction. Furthermore, the impacts of physicochemical properties (specific surface areas, pore volumes, average pore diameter, and acidity) in increasing the efficiency of γ-Al2O3@Gr-Cu nanocomposite catalysts in the HDT reactions of DBT/Quinoline model fuel and vacuum gas oil (VGO) have been thoroughly investigated. It has been found that growing graphene on γ-Al2O3 could reduce particle size and expand the specific surface area of γ-Al2O3@Gr nanocomposite catalysts, resulting in higher HDT activity. Raman spectroscopy, XRD, HR-TEM, SEM, BET surface, ICP, TPD, and TPR techniques with a view to linking catalytic activities with the synthesis method and Mo/W ratio were used to fully characterization of the prepared nanocomposite catalysts. Catalytic activities of γ-Al2O3@Gr-Cu nanocomposite are studied by varying operating conditions in the hydrotreating of VGO feedstock. It transpires that NiMo3W10/γ-Al2O3@Gr-Cu nanocomposite catalyst with the highest turnover frequency (3.8×104 s−1), high surface area (330 m2. g−1), large pore size (95.8 Å), and acidity (1.92 mmol NH3 g−1) have the best adsorption properties compared with a commercial catalyst which lead to an increase in the synergistic effect in trimetallic NiMoW catalysts related to the tighter interaction between W and Mo, which enhanced the solidification degree of metal and was also ascribed to the organization of significantly active mixed NiMoWS sites.

Impact on the Photocatalytic Dye Degradation of Morphology and Annealing-Induced Defects in Zinc Oxide Nanostructures.

In this study, three different morphologies, nanoflower (NF), nano sponge (NS), and nano urchin (NU), of zinc oxide (ZnO) nanostructures were synthesized successfully via a mild hydrothermal method. After synthesis, the samples were annealed in the atmosphere at 300, 600, and 800 °C. Although annealing provides different degradation kinetics for different morphologies, ZnO NS performed significantly better than other morphologies for all annealing temperatures we used in the study. When the photoluminescence, electron paramagnetic resonance spectroscopy, BET surface, and X-ray diffraction analysis results are examined, it is revealed that the defect structure, pore diameter, and crystallinity cumulatively affect the photocatalytic activity of ZnO nanocatalysts. As a result, to obtain high photocatalytic activity in rhodamine B (RhB) degradation, it is necessary to develop a ZnO catalyst with fewer core defects, more oxygen vacancies, near band emission, large crystallite size, and large pore diameter. The ZnO NS-800 °C nanocatalyst studied here had a 35.6 × 10-3 min-1 rate constant and excellent stability after a 5-cycle photocatalytic degradation of RhB.

The role of phase transition by inception and surface reactions for the synthesis of silicon nanoparticles in a hot-wall reactor – Simulation and experiment

A novel Eulerian particle model tailored for the application in computational fluid dynamics (CFD) is presented. The model is based on a bivariate moment method and features a full coupling with the gas-phase by kinetic formulations for inception, and activated and non-activated surface reactions. A new formulation for the particle composition accounts for the volatile content and its emission. The model is applied in the context of silicon nanopowder synthesis from monosilane, where a validation is performed with a well-established hot-wall reactor experiment from the literature. It is characterized by high precursor concentrations at moderate heating temperature of 853 K. Further, a new experiment was conducted for the comparison with the new model approach in a three-dimensional, transient simulation. The semi-industrial hot wall reactor features an unsteady complex flow field with buoyancy driven recirculation. The simulations enable new insights into the unsteady flow, mixing and nanoparticle formation process and contribute to their understanding. For the validation, residence-time dependent data for the precursor concentration, the primary particle size, and the particle number concentration are compared with results of the simulation at different stages. A comparison with the results of stochastic methods serves as further benchmark for the presented model. An excellent agreement with the experimental data is obtained, if essential growth mechanisms are considered. For the semi-industrial hot-wall reactor experiment, the BET surface and particle diameter, as well and the precursor consumption, are compared to the results of the new model and to a description with inception, coagulation, and sintering only. Due to the absence of crucial activated and non-activated surface reactions, the latter model predicts values that deviate more than one order of magnitude from the experimental data, while the new model shows an overall good agreement.

Effects of ion-exchange on the pervaporation performance and microstructure of NaY zeolite membrane

Pervaporation performance of NaY zeolite membranes is improved by ion-exchange with di-valent nitrate salt. Different nitrate salts, including Co(NO3)2, Mg(NO3)2, Zn(NO3)2, Ca(NO3)2, Cu(NO3)2, KNO3, and AgNO3, have great effects on the channel structure and water affinity of the NaY zeolite membrane. When the concentration of nitrate salt, ion-exchange temperature and time are 0.1 mol·L−1, 50 °C and 2 h, the ion-exchange degree order of NaY zeolites is Ag+ > K+ > Ca2+> Zn2+ ≫ Co2+ > Mg2+. Especially, Ag+ and K+ cation exchange degree of NaY zeolites are achieved to 96.54% and 82.77% in this work. BET surface, total pore capacity, pore size distribution and water contact angle of the ion-exchanged NaY zeolites are all disordered by mono- and di-valent cations. Di-valent nitrate salt is favor for increasing the dehydration performance of NaY zeolite membranes by ion-exchange. When the ion-exchange solution is Zn(NO3)2, the total flux variation and separation factor variation of the NaY membrane (M-5) are −45% and 230% for separation of 10% (mass) H2O/EtOH mixture by pervaporation, and the ion-exchanged membranes showed good reproducibility.

Production, Activation and CO2 Uptake Capacity of a Carbonaceous Microporous Material from Palm Oil Residues

While Malaysia produces about half of the world’s palm oil and is the largest producer and exporter worldwide, oil palm industries generate large amounts of lignocellulosic biomass waste as a sub-product with no economic market value other than feedstock for energy valorisation. With the aim to increase the sustainability of the sector, in this work we prepare new materials for CO2 capture from palm oil residues (empty fruit bunches and kernels). The biochar is obtained through the carbonisation of the residues and is physically and chemically activated to produce porous materials. The resulting microporous samples have similar properties to other commercial activated carbons, with BET surfaces in the 320–880 m2/g range and pore volumes of 0.1–0.3 cm3·g−1. The CO2 uptake at room temperature for physically activated biochar (AC) was 2.4–3.6 mmolCO2/gAC, whereas the average CO2 uptake for chemically activated biochar was 3.36–3.80 mmolCO2/gAC. The amount of CO2 adsorbed decreased at the highest temperature, as expected due to the exothermic nature of adsorption. These findings confirm the high potential of palm oil tree residues as sustainable materials for CO2 capture.

Preparation and Microwave Absorbing Properties of Yolk Shell C@C Microspheres

As a typical dielectric loss medium, carbon material has always been the most attractive candidate material for microwave absorption because of its characteristic advantages. However, much less attention has been paid to the reasonable design of micro-structure to improve its performance. According to the transmission behavior and loss mechanism of electromagnetic wave, uniform yolk shell C@C microspheres as a new type of microwave absorbers were creatively prepared by "coating-coating-etching". Compared with solid carbon microspheres, the unique micro-structure endows better BET surface and pore volume to the yolk shell C@C microspheres. The microwave absorption performance was tested in the frequency range of 2GHz to 18GHz. As expected, the yolk shell C@C microspheres exhibit excellent reflection loss characteristics, with strong reflection loss (-41.84dB at 9.2GHz) and wide effective absorption bandwidth(7.9~10.2GHz). This good performance is so for indeed better than most pure carbon absorbers reported. The electromagnetic parameters show that the yolk shell structure is conducive to the matching of characteristic impedance and can obtain ideal microwave absorption ability.

Pollution Removal Performance of Chemically Functionalized Textile Waste Biochar Anchored Poly(vinylidene fluoride) Adsorbent

Preparation of adsorbent materials in powder and polymeric composite form was achieved by controlled carbonization of ZnCl2 pretreated textile waste at low temperatures. Structural and surface properties of carbonized textile waste samples (CTW) and polymeric composites were prepared by the addition of CTW to PVDF-DMF solution at 0, 5, 10, 15, 20, and 30 mass% ratios analyzed by FT-IR, XRD, SEM, and BET analysis. Adsorption performances of powder and composite adsorbents were investigated for MO dye removal from an aqueous solution. Zn-CTW obtained with carbonization of ZnCl2 treated textile waste at 350 °C presented 117.5 mg/g MO removal. Those were higher than CTW-350 and CTW-400. The presence of 1545 cm-1 band at the IR spectrum of Zn-CTW proved the formation of functional groups that increase dye adsorption performance with honeycomb-like pores on the surface. Zn-CTW reflected its properties onto the PVDF matrix. Improved porosity percentage, BET surface, and dye adsorption of Pz20 were recorded as 105.3, 15.22 m2/g, and 41 mg/g, respectively, compared with bare PVDF. Disposal of textile waste and preparation of functional activated carbon were achieved in a low-cost and easy way. Zn-CTW loaded PVDF composites are promising materials to use as a dye removal adsorbent from water or filtration membranes.

5-Fluorouracil-containing inorganic iron oxide/platinum nanozymes with dual drug delivery and enzyme-like activity for the treatment of breast cancer

Intrinsic enzyme-mimic activity of inorganic nanoparticles has been widely used for nanozymatic anticancer and antibacterial treatment. However, the relatively low peroxidase-mimic activity (PMA) and catalse-mimic activity (CMA) of nanozymes in tumor microenvironment has hampered their potential application in the cancer therapy. Therefore, in this study, we aimed to fabricate platinum (Pt) nanozymes dispersed on the surface of iron oxide (Fe 3 O 4 ) nanosphere that, in addition to boosting the PMA and CMA, resulted in the formation of a pH-sensitive nano-platform for drug delivery in breast cancer therapy. After development of Fe 3 O 4 nanospheres containing Pt nanozymes and loading 5-fluorouracil (abbreviated as: Fe 3 O 4 /Pt-FLU@PEG nanospheres), the physicochemical properties of the nanospheres were examined by electron microscopy, dynamic light scattering, zeta potential, X-ray diffraction, thermogravimetric, BET surface, and PMA/CMA analyses. Then, the cytotoxicity of the Fe 3 O 4 /Pt-FLU@PEG nanospheres against 4T1 cells was investigated by the cell counting kit-8 assay and flow cytometry. Also, the anticancer effect of fabricated nanoplatform was assessed in mouse bearing 4T1 cancer tumors, in vivo . The results showed that the Fe 3 O 4 /Pt-FLU@PEG nanospheres provide a platform for optimal FLU loading, continuous pH-sensitive drug release, and potential PMA and CMA to increase the level of ROS and O 2 , respectively. Cytotoxicity outputs showed that the Fe 3 O 4 /Pt-FLU@PEG nanospheres mitigate the proliferation of 4T1 cancer cells mediated by apoptosis and intracellular generation of reactive oxygen species (ROS). Furthermore, in vivo assays indicated a significant reduction in tumor size and overcoming tumor hypoxia. Overall, we believe that the developed nanospheres with dual enzyme-mimic activity and pH-sensitive drug delivery can be used for ROS/chemotherapy double-modality antitumor therapy.

Synthesis of metal-organic framework HKUST-1 via tunable continuous flow supercritical carbon dioxide reactor

Scaling-up synthesis of metal–organic framework (MOF) materials is critical for their practical applications. Due to its unique properties, supercritical carbon dioxide (scCO2) is an attractive media single-step synthesis of MOFs. This paper, for the first time, presents a rapid synthesis of the high-quality copper-based MOF HKUST-1 in a continuous flow scCO2 flow reactor, evaluating the effects of pressure, scCO2 injection temperature, scCO2 mass fraction, and the reactor residence time on HKUST-1 properties over 23 experiments. The morphology, crystallinity, and porosity of MOF are characterized by scanning electron microscopy, X-ray diffraction, and physisorption analysis. Four sets of experiments showed excellent repeatability in particle size and specific surface area yielding high-quality HKUST-1 MOFs. The particle sizes ranged from 55 to 300 nm with an average of 135 nm, and the BET surface -- from 1,374 to 2,389 m2·g−1 with an average of 1,712 m2·g−1. Longer residence time increased particle size and led to MOF shape change from spherical to octahedral; however, these did not significantly correlate with MOF surface area. Pressure variation in the 8–10 MPa range did not impact HKUST-1 properties. Reactant temperature variations between 80 and 120 °C showed a weak correlation with particle size. Increasing reactor section temperature independently of the reactant temperature had a statistically significant negative correlation to particle size, r-value = -0.86, and p-value = 0.04. The scCO2-assisted synthesis yielded high-quality MOFs under all studied conditions with residence time in the range of 70–170 s, demonstrating the robustness and high throughput of the method.

Natural Volcanic Material as a Sustainable Photocatalytic Material for Pollutant Degradation under Solar Irradiation.

Recently, photocatalysis has been demonstrated as a solid approach for efficient wastewater cleaning. Using natural materials as photocatalysts means a promising solution to develop green catalysts for environmental purposes. This work aimed to study the suitability of a natural volcanic material (La Gomera, Canary Islands, Spain) as a photocatalytic material for the degradation of pollutants in wastewater with solar energy. After analysing the properties of the natural material (BET surface 0.188 m2/g and band-gap of 3 eV), the photocatalytic activity was evaluated at laboratory and pilot plant scale for the degradation of methylene blue (MB) in water (50 mg L−1), at 20 °C, during a period of 4 h, under UV/Vis light and solar irradiation. Photolytic and adsorption studies were developed to distinguish the photocatalytic contribution to the wastewater decontamination process by photocatalysis. Our results enable us to determine the viability of black sand as a photocatalytic material activated by solar irradiation (photodegradation of MB up to 100% by using solar energy), developing a natural and green photocatalytic system with significantly high potential for application in a sustainable wastewater cleaning process.

The Effect of Chemical Activation Method in the Preparation of Activated Carbon from Local Phoenix Dactylifera Waste Stems

Local date palm (Phoenix dactylifera) waste stems were used to prepare activated carbon (AC) using KOH, NaCl and ZnCl2 as activation agents. Carbonization was conducted at 600 °C for 2hr under nitrogen flow, followed by activation at 750 °C for 2 hr under carbon dioxide flow. AC was characterized using a scanning electron microscope (SEM), Attenuated total reflectance Fourier transform infrared (ATR FT-IR), Thermogravimetric analysis (TGA), Iodine adsorption, BET, micropores, and mesopores surface areas at different carbon-to-activation-agent-ratios (1:1, 1:2, 1:3). FT-IR spectra results showed a reduction in AC-NaCl bands compared to other AC, which indicates less functional surface groups. At 750 °C, the TGA analysis showed the carbon yield as AC-ZnCl2 &gt; AC-NaCl &gt; AC-KOH, however, among all samples, AC-NaCl at 1:2 ratio was the best in terms of iodine removal. This treated AC sample exhibited about 18.3 % maximum iodine removal, which indicates the high surface area and porosity with 550.4380 m2/g, 348.7432 m2/g, and 201.6947 m2/g BET, micropores and mesopores surface areas, respectively. In conclusion, the local Omani date palm waste stems can be used for AC production with a well porous structure using cheap and environmentally friendly salts as activation agents. In addition, the produced AC attained better adsorption characteristics among other alternatives.

Synthesis of CuFe2O4‐Ti and CuFe2O4‐Ti‐GO nanocomposite photocatalysts using green‐synthesized CuFe2O4: determination of photocatalytic activity, bacteria inactivation and antibiotic degradation potentials under visible light

AbstractBACKGROUNDAdvanced oxidation processes (AOPs), specifically photocatalysis have gained an essential attraction in the field of micro pollutants degradation. Synthesis and use of proper photocatalysts for target pollutant and water matrix scenarios constitute the primary field of research.In this study, hydrothermal and sol‐gel synthesis methods were applied for the synthesis of nanocomposites in the form of spinel ferrite CuFe2O4 (CF) nanocomposites and CuFe2O4‐Ti (CFT) and CuFe2O4‐Ti‐GO (CFT‐GO) heterojunction nanocomposites with magnetic properties. And prior to photocatalytic activity based screening, bacteria inactivation and antibiotic degradation potentials of optimum NCs were determined under visible light conditions.PEG and Cydonia oblonga seed extract were used as chemical and bio‐chemical reducing‐stabilizing agents throughout the hydrothermal synthesis step. The as produced NCs were characterized by XRD, SEM, EDX, BET Surface, FTIR, RAMAN, Photoluminescence and Diffuse Reflectance Spectroscopy analysis.RESULTSAccording to the pre‐screening findings based on the methylene blue removal efficiencies of NCs under UV‐vis, CFT %1(w/w) have provided &gt;70% removal at the end of 120 min. While CFT‐GO NCs yielded 30% removal rates (Pseudo first order kinetic constants of 0.012 and 0.0036 min−1 respectively). The reactive oxygen species formation by CFT‐GO NC photocatalysts was hindered as a result of conjugation mechanism between MB and aromatic regions of GO and due to high adsorption capacity of the NC.Based on photocatalytic bacteria inactivation findings of the pre‐screened NCs; &gt;99% of bacteria were inactivated following 90 min of photocatalytic oxidation by CFT‐GO 3%. According to the Modified HOM model, k2 values were estimated to be 1.36 and 1.93 for CFT 1% and CFT‐GO 3% NCs, while no initial and post delay of bacteria inactivation was observed for the latter.Optimum photocatalyst dose was examined (to be 0.6 g L−1) based on photocatalytic degradation of sulfamethoxazole antibiotic at varying initial concentration ([C]0 SMX = 10 and 2.5 mg L−1). The CFT 1% photocatalysts have provided &gt;89 % SMX degradation level (for [C]0 SMX = 2.5 g L−1). For the case of mixture of antibiotics [C]0 total = 2.5 g L−1, CFT 1% have provided &gt;99.5%, &gt;90%, &gt;90% and 28% photocatalytic degradation levels at the end of 180 min for SMX AMP, TET and CLRT antibiotics respectively, while the total rate of degradation was 77%.CONCLUSIONBy using the green synthesis procedure, copper ferrite nanocomposites (CF) was successfully fabricated with comparable physical and chemical properties. This study not only reports on the green synthesis of common p‐type spinel CuFe2O4 but also offer new design of photocatalysts capable of providing efficient removal of antibiotics and bacteria inactivation under visible‐light irradiation. © 2022 Society of Chemical Industry (SCI).

Pyrolysis behaviors of corn stover in new two-stage rotary kiln with baffle

An instantly moving, two-stage rotary kiln reactor with baffle was proposed for the conversion of biomass to fuels and biochar. This newly configured apparatus enhanced the material particle mobility in the dead zone, but also enable ideally matched the material heating process in pilot-scale biomass pyrolysis. The thermogravimetric (TG) analysis and the distributed activation energy model (DAEM) was utilized to determine the pyrolysis kinetic of corn stover in this study. Meanwhile, the pyrolysis behaviors of corn stover were investigated in this newly designed rotary kiln, as well as the bio-oil, char and gas products. The pyrolysis experiment results indicated that this newly configured apparatus presented higher bio-oil yield and pyrolysis liquid products yield than a conventional rotary kiln. The bio-oil yield increased initially and subsequently declined with rising temperature, as did the yields of pyrolysis liquids and water, but not biochar in this newly configured apparatus. Raising the temperature from 400 °C to 700 °C increased the bio-oil yield from 14.02 wt% to 23.02 wt%, whereas increasing the temperature further to 800 °C decreased the bio-oil yield to 22.16 wt%. Bio-oil was mostly composed of ketones, phenols, furfurans, benzenes, and esters, with a large proportion of oxygen-containing compounds. The phenols compounds increase with increasing temperature, aldehydes, ketones and furans decreased in relative contents. The increased temperature raised the H2, CH4, and C2+C3 contents, but decreased the CO content. The BET surface and total volume of biochar rose first and subsequently declined with rising temperature. The proximate analysis of biochar revealed metal volatilization process, and although the pH of biochar increased with rising temperature but HHV (high heat value) of the biochar decreased.

Mesityl Oxide Reduction by Using Acid-Modified Phonolite Supported NiW, NiMo, and CoMo Catalysts

Mesityl oxide is standardly used to produce methyl iso butyl ketone but it can be also used to produce other useful compounds. Three catalysts were used for the reaction of the mesityl oxide reduction. They were NiW, NiMo, and CoMo supported on phonolite modified by HCl (metals/Ph-HCl). The fresh catalysts were characterized by XRD, XRF, BET surface, Hg porosimetry, SEM, H2-TPR, NH3-TPD, CO2-TPD. The materials were directly used, previously reduced in H2 or sulfided for the mesityl oxide reduction under H2 atmosphere. The reaction was performed in an autoclave at T = 375 °C, p = 50 bar (H2), and TOS = 1.5 h. The products were analyzed by GC/MS, GC/FID-TCD, ATR. The main products were methyl isobutyl ketone, 2-methyl pentane, and 2-methyl-2-pentene. Sulfided metal catalysts were the most active in the methyl isobutyl ketone, where the NiWSx/Ph-HCl catalyst showed the highest activity. For the non-previously-activated and hydrogen activated catalysts the most active catalyst was the NiMo/Ph-HCl for the production of methyl isobutyl ketone. The catalyst CoMo/Ph-HCl activated in hydrogen was the most active for the production of 2-methyl pentane compared to the other two hydrogen-activated materials.

Synthesis of Hierarchical MOR-Type Zeolites with Improved Catalytic Properties.

Hierarchical MOR-type zeolites were synthesized in the presence of hexadecyltrimethylammonium bromide (CTAB) as a porogen agent. XRD proved that the concentration of CTAB in the synthesis medium plays an essential role in forming pure hierarchical MOR-type material. Above a CTAB concentration of 0.04 mol·L−1, amorphous materials are observed. These hierarchical mordenite possess a higher porous volume compared to its counterpart conventional micrometer crystals. Nitrogen sorption showed the presence of mesoporosity for all mordenite samples synthesized in the presence of CTAB. The creation of mesopores due to the presence of CTAB in the synthesis medium does not occur at the expense of zeolite micropores. In addition, mesoporous volume and BET surface seem to increase upon the increase of CTAB concentration in the synthesis medium. The Si/Al ratio of the zeolite framework can be increased from 5.5 to 9.1 by halving the aluminum content present in the synthesis gel. These synthesized hierarchical MOR-type zeolites possess an improved catalytic activity for n-hexane cracking compared to large zeolite crystals obtained in the absence of CTAB.