Adsorption-desorption Isotherms Research Articles

In Ukrainian

The CMs were obtained in argon in three stages: 1) heating (4 grad/min) to the specified temperature t in the range of 350–825 °С; 2) isothermal exposure 1 h; 3) cooling, washing from alkali and drying. Samples are denoted as CM(t). The CM yield (Y, %) and CMs elemental composition are determined. Based on low-temperature (77 K) nitrogen adsorption-desorption isotherms, integral and differential dependences of the specific surface area SDFT (m2/g) and pore volume V (cm3/g) on the average pore diameter (D, nm) were calculated by 2D-NLDFT-НS method (SAIEUS program). They were used to define volumes of ultramicropores (Vumi), supermicropores (Vsmi) and micropores (Vmi). The total pore volume V was calculated from the nitrogen amount adsorbed at a relative pressure p/p0 ~ 1.0. The S values of ultramicropores (Sumi), supermicropores (Ssmi) and micropores (Smi) were similarly determined. The CM yield was established to decrease linearly (R2 = 0.979) from 70.2 to 45.3 % with an increase in temperature from 350 to 825 °С. The carbon content decreases to a minimum value at 500 °С (72.6 %), and then increases to a maximum value (87.5 %) at 825 °С; the oxygen content changes antibatically. Two temperature regions were identified: region I (≤ 500 °С) of increasing the oxygen content due to reactions in which KOH acts as a donor of O atoms; region II (≥ 500 °C) of dominating the thermal destruction of functional groups (carboxyl, lactone, ester) with the release of CO and CO2, and condensation increasing the size of polyarenes of the CM secondary framework and formsng single Сar-Саr bonds between them. The CM(350) sample was found to contain only mesopores (D ≥ 10 nm) and macropores. An activation temperature increase to 400 °C initiates the additional formation of small-diameter micropores and mesopores. In samples CM(400) - CM(825), the main portion of newly formed pores falls on pores with D ≤ 5 nm. With increasing temperature, the micropores volume increases almost linearly (R2 = 0.992). The Vumi and Vsmi volumes increase up to 600 °C. At higher temperatures the ultramicropores volume decreases due to transforming ultramicropores (D ≤ 0.7 nm) into supermicropores (D = 0.7–2.0 nm). Portion of the ultramicropores volume changes with a maximum (23.9 %) in the CM(600) sample. The SBET specific surface area linearly (R2 = 0.992) increases with temperature up to 1729 m2/g. The SDFT values are close to SBET, but noticeably lower (1514–1530 m2/g) for CM(785)-CM(825). The micropores specific surface area increases to 1415 m2/g, and ultramicropore surface Sumi changes extremely with a maximum (526 m2/g) for the CM(600) sample, which should be expected based on the temperature dependence of the Vumi parameter. The decrease in Sumi values after the maximum is compensated by an increase in the supermicropore surface. Such an effect - the redistribution of pores by size in the microporous range (D ≤ 2 nm) with an increase in the alkaline activation temperature is not described in the literature. The portion of the micropores surface is dominant (92.6–97.0 %) in samples prepared at t ≥ 450 °C. The portion of the ultramicropore surface is maximum (56.3 %) in CM(500). Pores are revealed that do not form at all at 450–750 °C. These are supermicropores (D = 0.96–2.00 nm) and mesopores of small diameters (D = 2.0–2.82 nm). This effect was assumed to be due to the properties of the CM supramolecular framework, which is formed from polyarene fragments of the initial and activated coals having polyarenes with diameters of the same order (1.68–2.54 nm).

Liquid phase oxidation of cyclopentanone over metal-free carbon catalysts

AbstractOxidation of cyclopentanone (CPO) was studied over metal-free carbon catalysts in solvent-free conditions. Norit SX plus (900 m2 g−1) and Vulcan XC72 (240 m2 g−1) were used as pristine materials. Catalysts were prepared by activation in nitrogen and by treatment with urea, calcined in nitrogen at 500 °C and 950 °C. SEM, EDX, XPS, X-ray powder diffraction, nitrogen adsorption–desorption isotherms, acid–base titration, FTIR and Raman techniques were used for characterization. Catalytic tests carried out at 0.45 MPa and 80–110 °C enabled to find the best results: 30% selectivity to glutaric acid (GA) and 3% to succinic acid at 25% conversion of CPO, over Vulcan type catalysts. A low activity, selectivity and strong deactivation of Norit type catalysts can be ascribed to a higher specific surface in a disordered arrangement providing a high concentration of unselective catalytic sites. A higher extent of side reactions can yield in higher molar mass products, which stick on the surface and block catalytic sites. Optimum amount of accessible planar domains, represented by graphene and/or graphitic plates with some disorders present in Vulcan type catalysts classified them superior to Norit catalysts. A redox reaction scheme of oxidation of CPO to GA is also proposed. Graphical abstract

Solid hydrogen storage with palladium-graphene composites: Synthesis, characterization, and mechanistic insights

Efficient and safe hydrogen storage is a pivotal challenge for the advancement of hydrogen energy technologies. To address this, the engineering of high-performance solid-state hydrogen storage materials through the loading of transition metals (TM) on carbon-based solids has gained considerable interest. However, the mechanics for TM such as Palladium that bolster hydrogen storage have not well addressed yet. This work presents hydrogen absorptions with metal Pd nanoparticles loaded on reduced graphene oxide (Pd-rGO), including material preparation, structural characterization, hydrogen storage performance, and quantum chemical mechanistic insights. A simple material synthesis strategy has been explored and Pd-rGO composites are successfully prepared with graphite powder as raw materials by an easy reduction-oxidation process. Then, Pd-rGO composites are characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, Raman, transmission electron microscopy, and nitrogen adsorption-desorption isotherms methods to clarify the detailed structural characteristics of Pd-rGO with different loading amounts. It is found that Pd nanoparticles with an average particle size of 10 nm are uniformly dispersed on the surface of rGO. The materials have high defect severity and increased specific surface areas with Pd loading. The hydrogen adsorption capacity of Pd-rGO can be increased by 64 % compared with that without Pd loading due to the hydrogen spillover effect. In addition, the intensification mechanism of hydrogen storage of Pd-rGO composites is further understood by using density functional theory calculations and surface interaction analysis.

Facile hydrothermal assembly of three-dimensional GO-MTZE composite and its adsorption properties toward Cu2.

Three-dimensional (3D) graphene oxide (GO)-based aerogels, GO and 4-methyl-5-thiazoleethanol (MTZE) composites, were prepared by a facile hydrothermal method. Due to the hydrogen bonding and π-π stacking interactions, the produced 3D GO-MTZE composites possessed large cylindrical structures. The morphologies, composition, and chemical states of 3D GO-MTZE3:1 composite were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and N2 adsorption-desorption isotherms based on the Brunauer-Emmett-Teller (BET) method. The existence of nitrogen (N)-containing heterocyclic system and oxygen (O)-containing branched chain of MTZE contributed to the formation of 3D structures, while the complexation effect of heterocyclic sulfur (S)- and N-containing functional groups of MTZE for metal cations dominated the adsorption performance of 3D GO-MTZE3:1 composite, which could selectively adsorb copper ions (Cu2+). In addition, the better hydrophobic property of 3D GO-MTZE3:1 composite facilitates its facile recycling from aqueous solution after adsorption. The adsorption data of 3D GO-MTZE3:1 composite toward Cu2+ fitted well (R2 = 0.9996) with the linear pseudo-second-order kinetic model, giving an equilibrium rate constant (k2) of 0.0187gmg-1min-1. The linear Langmuir isothermal model could more accurately describe the experimental data, indicating the adsorption process is mainly dominated by the complexation interactions between MTZE and Cu2+. The thermodynamic parameters of ΔG° (< 0), ΔH° (> 0), and ΔS° (> 0) further indicate that the adsorption is a spontaneous and endothermic, confirming that the complexation between Cu2+ and 3D GO-MTZE3:1 composite occurs. Due to its high selectivity for Cu2+, good hydrophobicity, and excellent stability, the developed 3D GO-MTZE3:1 composite possesses might be promisingly used in the aqueous selective enrichment/removal of Cu2+.

Simultaneous synthesis of super-paramagnetic hydrochar in a one-pot using subcritical water medium and evaluation of its photocatalytic activity

The unregulated release of chemical dyes into the environment presents considerable environmental hazards when left untreated. Photocatalytic degradation, acknowledged as an eco-friendly and cost-effective method, has garnered attention for its efficacy in eliminating organic pollutants like dye. Consequently, the development of multifunctional materials with different applications in environmental and catalytic fields emerges as a promising avenue. Recognizing the significance of integrating catalysts and porous materials for enhancing interactions between pollutants and photo-sensitive substances, magnetic hydrochar emerges as a solution offering heightened efficiency, scalability, recyclability, and broad applicability in various environmental processes, notably wastewater treatment, due to its facile separation capability. In this study, Fe3O4-based, super-paramagnetic hydrochar (SMHC) was simultaneously synthesized in a single step using a coconut shell in the subcritical water medium. A thorough analysis was conducted on both raw hydrochar (RHC) and SMHC to unravel the mechanism of interaction between Fe3O4 nanoparticles and the hydrochar matrix. The synthesized hydrochar exhibited super-paramagnetic characteristics, with a saturation magnetization of 23.7 emu/g and a magnetic hysteresis loop. SMHC displayed a BET surface area of 42.6 m2/g and an average pore size of 26.3 nm, indicating a mesoporous structure according to nitrogen adsorption-desorption isotherms. XRD analysis revealed magnetic crystal sizes in the obtained SMHC to be 13.7 nm. The photocatalytic performance of SMHC was evaluated under visible light exposure in the presence of H2O2 for Astrazon yellow (AY) dye degradation, with optimization conducted using response surface methodology (RSM). The most substantial dye removal, reaching 92.83%, was achieved with 0.4% H2O2 at a 20 mg/L dye concentration and an 80-min reaction duration.

Kinetic study of adsorption and photocatalytic degradation of methylene blue dye using TiO2 nanoparticles with activated carbon

Activated carbon (AC) exhibits limited adsorption capacity for pollutants. Conversely, titanium dioxide (TiO2) demonstrates excellent photocatalytic performance, making it a popular choice for pollutant removal. This study investigates the removal of methylene blue (MB) dye from wastewater using AC, TiO2@AC-2, and TiO2@AC-10 samples via adsorption and photocatalysis. The Energy Dispersive analysis of x-rays (EDAX) has confirmed the presence of Ti, C and O in the prepared samples without any impurities. All the diffraction peaks in x-ray diffractograms indicated the presence of pure anatase TiO2 (tetragonal phase) with no evidence of any other phase. Fourier transform infrared spectroscopy (FTIR) analysis identified a peak around 545 cm−1 in the TiO2@AC-2 sample, indicative of O-Ti-O stretching vibrations. This peak shifted to 602 cm−1 in the TiO2@AC-10 sample. Raman spectroscopy confirmed the presence of carbon (D and G bands) at 1310–1347 cm−1 and 1582–1597 cm−1. Additionally, characteristic Raman active bands for anatase TiO2 were observed at 154 cm−1 (Eg), 204 cm−1 (Eg), 398 cm−1 (B1g), 508 cm−1 (A1g), and 628 cm−1 (Eg). N2 adsorption–desorption isotherms revealed a mesoporous structure for all samples (AC, TiO2@AC-2, and TiO2@AC-10) with hysteresis loops, indicating pores ranging from 2 nm to 50 nm in diameter. Reflectance spectra of TiO2@AC-2 and TiO2@AC-10 displayed absorption edges at 368 nm and 385 nm, respectively, corresponding to a direct band gap of approximately 3.22 eV. Subsequently, these prepared samples were effectively employed for the removal of methylene blue (MB) dye from wastewater utilizing both adsorption and photocatalysis method. Under dark conditions, 20 mg L−1 doses of TiO2@AC-2 and TiO2@AC-10 resulted in 60% and 36% dye adsorption within 60 min respectively. In the presence of UV radiation, the degradation of dye was observed to be 74% and 95% by TiO2@AC-2 and TiO2@AC-10 respectively. This observation indicates that TiO2 nanoparticles along with AC leads to enhanced photocatalytic activity. The Langmuir–Hinshelwood model reveals lower rate constants for AC compared to the composite samples. This is likely because AC lacks inherent catalytic activity, requiring UV light to trigger adsorption. Conversely, TiO2@AC-10 exhibits the highest rate constants (K1 = 24.25 × 10−3 min−1 and K2 = 82.71 × 10−3 min−1), aligning with its higher TiO2 content confirmed by EDAX analysis. This suggests a significantly faster photocatalytic rate and superior degradation efficiency, even at a low sample concentration (20 mg L−1).

Novel controllable (Ba0.8Sr0.2)CO3@Mesoporous silicate core/shell nanocomposite grafted fluorescent probes for colorimetric, sensing, and selective detection of heavy metals

Fluorescent nanosensors are one of the most efficient techniques used for detection of toxic metal ions, based on ligand embedded into mesoporous materials. In this study, four different novel nanosensors NS1, NS2, NS3, and NS4 have been synthesized by incorporating fluorescent probes containing dihydropyridine and dihydropyrimidinone fragments into amino‐functionalized controllable (Ba0.8Sr0.2)CO3@Mesoporous silicate core/shell nanocomposite. The designed nanosensors were characterized by FT‐IR (Fourier‐transform infrared spectroscopy), X‐ray diffraction, transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms. Visual naked‐eye observations and emission technique were employed to investigate the recognition and sensing capability of the investigated nanosensors toward various metal ions (Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, and Cu2+). A great quenching in the fluorescence intensity was clearly observed with the majority of studied metal ions for all the nanosensors. The binding constants and limit of detection (LOD) have been calculated. Cu2+ is the strongest binded one with both NS1 and NS2, while Al3+ and Fe3+ are the strongest binded metal ions with NS3 and NS4, respectively. The obtained results confirmed the high ability of the nanosensors to detect heavy metals ions at environmentally relevant concentrations using simple and low‐cost experimental studies with good reversibility and reusability.

Synthesis of Calix[4]arene-Based Porous Organic Cages and Their Gas Adsorption.

Two crystalline large-sized porous organic cages (POCs) based on conical calix[4]arene (C4A) were designed and synthesized. The four-jaw C4A unit tends to follow the face-directed self-assembly law with the planar triangular building blocks such as tris(4-aminophenyl)amine (TAPA) or 1,3,5-tris(4-aminophenyl)benzene (TAPB) to generate a predictable cage with a stoichiometry of [6+8]. The formation of the large cages is confirmed through their relative molecular mass measured using MALDI-TOF/TOF spectra. The protonated molecular ion peaks of C4A-TAPA and C4A-TAPB were observed at m/z 5109.0 (calculated for C336H240O24N32: m/z 5109.7) and m/z 5594.2 (calculated for C384H264O24N24: m/z 5598.4). C4A-POCs exhibit I-type N2 adsorption-desorption isotherms with the BET surface areas of 1444.9 m2 ⋅ g-1 and 1014.6 m2 ⋅ g-1. The CO2 uptakes at 273 K are 62.1 cm3 ⋅ g-1 and 52.4 cm3 ⋅ g-1 at a pressure of 100 KPa. The saturated iodine vapor static uptakes at 348 K are 3.9 g ⋅ g-1 and 3.5 g ⋅ g-1. The adsorption capacity of C4A-TAPA for SO2 reaches to 124.4 cm3 ⋅ g-1 at 298 K and 1.3 bar. Additionally, the adsorption capacities of C4A-TAPA for C2H2, C2H4, and C2H6 were evaluated.

A field study of pore-network systems on the tight shale gas formation through adsorption-desorption technique and mercury intrusion capillary porosimeter: Percolation theory and simulations

Properly identifying microscopic pore structure properties of shale reservoirs is essential for developing efficient extraction techniques of shale hydrocarbons. To understand the unique and complex pore network of the Northern Guizhou shale reservoir, shale samples from the Wufeng-longmaxi Formation were investigated using different analytical techniques, X-Ray Diffractometry, low-pressure nitrogen gas adsorption-desorption isotherms, and Mercury intrusion capillary porosimeter. Results indicate that the Wufeng-longmaxi formation is mainly composed of a high quantity of quartz ranging from 0.6 % to 64.1 % and an average extent of 55.825 %, the lowest amount of potassium feldspar ranging from 0.6 % to 2.2 % and an average extent of 1.45 % with Total organic contents ranging from 3.672 to 5.209 %. Similarly, the BJH adsorption techniques for pore volume and area were investigated. The results indicate the dominance of the mesopore with pore size ranging from 2.03 nm to 40nm, average pore volume of 0.073715 m3/g, and average pore area of 13.0324 m2/g. The pore throat distributions from MICP showed drain pressure and median pore throat radius ranging from 0.47 to 13.79 MPa and 0.05–0.08 μm, respectively. Suggested complementary experimental techniques reveal the connectivity of pore networks of the Wufeng-longmaxi Formation shale reservoir, which shows a high production potential of hydrocarbons. The findings of this study can provide a valuable understanding of fluid transport properties and storage space of shale gas that can help decision-makers as they set exploration initiatives for shale gas reservoirs.

Interaction of composite fume suppression and odor elimination agents with crumb rubber modified asphalt: Inhibition behavior of volatile organic compounds (VOCs) and inorganic fume

The production and construction of crumb rubber modified asphalt (RMA) at high temperatures can produce a large amount of toxic fume, which is detrimental to human health and environment. In this study, a series of composite fume suppression and odor elimination agents (CSEAs) with both physical adsorption and chemical capture functions were adopted to reduce the emissions of volatile organic compounds (VOCs) and hydrogen sulfide (H2S). The material composition, microstructure, and specific surface area of CSEA were analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and N2 adsorption-desorption isotherm (BET). The inhibitory effects of adding CSEA on toxic fume emissions from RMA at high temperatures were investigated through a combination of fume emission tests, H2S gas detection, gel permeation chromatography (GPC), and gas chromatography–mass spectrometry technology (GC–MS). The adsorption behavior of CSEA on H2S was analyzed through adsorption dynamics. Results showed that the physical and chemical properties of CSEA are stable while chemical adsorption dominates the CSEA's effect on H2S. ZnO and Ca(OH)2 exhibit good crystallization effects on the surface of the carrier by forming mesoporous structures mostly above 3.4 nm in size. The incorporation of CSEA significantly reduced the total emissions of RMA fume and the main components of VOCs in which the average inhibition rate of H2S can reach 44 % at an initial 30 mins.

Management of caffeine in wastewater using MOF and perovskite materials: optimization, kinetics, and adsorption isotherm modelling

Pharmaceuticals and personal care products (PPCPs) have been increasingly used all over the world and they have been reported on water cycle and cause contamination. Among these pharmaceuticals is caffeine (CAF). In this work, CAF removal from aqueous samples by metal–organic framework (UIO-66) and perovskite (La0.7Sr0.3FeO3) was achieved. Detailed studies on the preparation of MOFs and perovskite oxides compounds have been presented. Extensive characterizations such as X-Ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared spectra (FT-IR), N2 adsorption–desorption isotherms were also carried out to assure proper formation and to better understand the physico-chemical behavior of the synthesized samples before and after adsorption. Batch experiments of CAF adsorption onto both MOFs and perovskite were performed to compare the effectiveness of both materials on the removal competence of the CAF residue at different conditions including the effect of pH, initial concentration, and contact time. It was observed that the adsorption capacity of CAF by MOF increased with increasing acidity. On the other hand, the adsorption capacity of perovskite is stable in pH 4–10. The maximum adsorption capacities of UiO-66 and perovskite toward CAF are high as 62.5 mg g−1 and 35.25 mg g−1, respectively. Equilibrium isotherms were investigated by numerous models: Langmuir, Freundlich, Temkin, Redlich-Peterson, Sips, Langmuir-Freundlich, Toth, Kahn, Baudu, and Fritz Schlunder. Moreover, the kinetics of the CAF@MOF and CAF@Perovskite systems have been studied by five kinetic models (Pseudo-1st -order (PFO), Pseudo-2nd -order (PSO), Mixed 1st, 2nd-order, Intraparticle diffusion and Avrami). The best model described the adsorption of CAF onto both of MOF and perovskite was the mixed 1st, 2nd-order model. The metal–organic framework and perovskite were applied to quickly extract CAF from water samples successfully. The maximum removal percentage obtained for MOF and perovskite was 0.89% and 0.94% respectively within 30 min contact time which suggests that these materials are considered as promising adsorbents for CAF.

The room temperature ethanol gas sensors based on MoS2-CuGaO2 composite prepared by hydrothermal method

In this paper, MoS2-CuGaO2 composites were successfully synthesized by hydrothermal method. The composites were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), respectively. The specific surface area and pore size distribution were obtained by N2 adsorption-desorption isotherms. The gas sensing property measurements were conducted. The sensitivity of pure CuGaO2 based gas sensor to 100 ppm acetic acid and benzene vapor was 1.4 at 25oC. The sensitivity of MoS2-CuGaO2 composite (M − 5) was 6.0 towards 100 ppm ethanol vapor at 25oC. And the detection limit of MoS2-CuGaO2 (M − 5) based sensor was 0.1 ppm. The results demonstrated that MoS2 had effect on the selectivity and sensitivity of the MoS2-CuGaO2 composites. M − 5 composite is considered to be promising for ethanol sensing application in room temperature.

Coin‐Shaped Carbon Prepared with Cerbera manghas Fibers via Multistage Carbonization and Activation for High‐Performance Symmetrical Supercapacitors

AbstractSupercapacitor energy storage devices and activated carbon (AC) manufacturing materials for producing high‐performance supercapacitors have received extensive attention from researchers. Biomass‐based AC has been extensively studied due to its environmental friendliness, abundant availability, porous structure, and high specific surface area. This work focuses on developing biomass‐based carbon electrodes derived from Cerbera manghas fiber (CMF) with variations in carbonization temperature to obtain optimum supercapacitor cell performance. The prepared CMF AC was characterized using energy dispersive X‐ray, Fourier transform infrared, X‐ray diffraction, scanning electron microscope, and nitrogen isothermal adsorption–desorption. CMF AC with the optimum carbonization temperature (CMF‐600) produced a fibrous structure with a lot of mesoporous so that the specific surface area and specific capacitance were high, namely, 721.495 m2 g−1 and 221 F g−1 at scan rate 1 mV s−1, respectively. The results of this study indicate that selecting the optimum temperature can enhance the performance of supercapacitor cells and make AC based on CMF biomass potential for cheap and efficient energy storage applications.

Mesoporous Pdx-Nix aerogels for electrocatalytic evaluation of urea-assisted electrolysis

AbstractThis work presents the synthesis and evaluation of Pd-Ni aerogels toward the urea oxidation reaction (UOR). The incorporation of Ni led to a 0.13 V reduction in the energy required for the oxidation and reduction of PdO compared to monometallic Pd, both in alkaline medium with and without urea. Varying the Ni ratios in Pd (Pd-Ni 4:1, Pd-Ni 1:1, and Pd-Ni 1:4) led to significant changes in the electrochemical behaviour. In alkaline medium without urea, PdNi 4:1 showed the formation of NiOOH at 1.35 V, which promoted oxygen diffusion on the electrode surface and increased the current density, confirming the increase in the active sites of NiOOH and NiPdOOH and enabling urea-based electrolysis at these sites. While palladium aerogels alone are ineffective for UOR, the presence of nickel plays a key role in enhancing the UOR efficiency. On the other hand, physicochemical characterisation revealed that PdNi 4:1 has a crystal size of 4.37 nm and a larger shift in the 2θ positions of the (111) and (200) planes, which favours electronic changes that were investigated by XPS. These changes affected the electrocatalytic activity, which is primarily related to electronic effects. The results of SEM and TEM studies and nitrogen adsorption-desorption isotherm confirmed that the aerogels are highly porous and have an effective surface area and abundant active sites for reactions that allow efficient mass transfer and low diffusion resistance. TEM observations revealed interconnected nanochains indicating optimal electrocatalytic activity for both ORR and UOR due to high mass transfer. These interconnected networks are crucial for improving electrocatalytic activity in the urea oxidation reaction.

A novel method for synthesis of nonylated diphenylamine by alkylation of diphenylamine with nonene over Fe-promoted SO42-/ZrO2 catalysts

As a green and efficient antioxidant, nonylated diphenylamine (NDPA) is of great significance to fields such as lubricants, synthetic rubber, and plastic. However, traditional catalysts for synthesizing NDPA still exhibit drawbacks of low efficiency, equipment corrosion, non-renewability, and environmental pollution. To overcome these challenges, a series of Fe-promoted SO42-/ZrO2 catalysts were successfully developed and employed for the first time in the alkylation of DPA and NON to synthesize NDPA in our present work. Both synthesis variables of catalysts and reaction conditions were well optimized. The as-synthesized NFe2.50S1.0Z catalyst possessed excellent catalytic performance with a high yield of mono- and di-nonyl-diphenylamine, as well as better reusability and stability than activated clay. After 5 reaction cycles, over 90 % of the catalytic activity could be recovered by the thermal treatment. These observations make the Fe-promoted SO42-/ZrO2 catalyst a promising candidate for industrials. Additionally, to systematically investigate and elucidate the promoting effects of Fe on sulfated zirconia catalysts, a thorough characterization of the physicochemical properties of these catalysts was conducted through various techniques, including XRD, SEM, TEM equipped with EDX, N2 adsorption-desorption isotherms, EA, ICP-OES, FT-IR, XPS, and NH3-TPD. The results indicated that the introduction of a small amount of Fe into the catalyst promoted the stabilization of T-ZrO2, smaller grain sizes, increased specific surface area, and strong acidity, which in turn positively affected the catalytic performance. In addition, a possible reaction mechanism of Fe-promoted SO42-/ZrO2 catalyst for catalyzing the alkylation of DPA with NON was proposed.

One-pot synthesis of quinazolinone heterocyclic compounds using functionalized SBA-15 with natural material ellagic acid as a novel nanocatalyst

The nanoporous compound SBA-15 was functionalized using (3-aminopropyl)trimethoxysilane (APTES). Then the obtained product was modified with ellagic acid (ELA), a bioactive polyphenolic compound. The structure of the prepared nanoporous composition SBA-15@ELA was extensively characterized and confirmed by various techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, Energy dispersive X-ray (EDX) elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption–desorption isotherms (BET). The novel, recoverable, heterogenous SBA-15@ELA nanoporous compound was used to investigate its catalytic effect in the synthesis of 4-oxo-quinazoline derivatives (19 examples) with high yields (78–96%), as an important class of nitrogen-containing heterocyclic compounds. The use of an inexpensive mesoporous catalyst with a high surface area, along with easy recovery by simple filtration are among the advantages of this catalysis research work. The catalyst has been used in at least 6 consecutive runs without a significant loss of its activity.

The Affects of Ce Doping Cr\(_2\)O\(_3\) Based Catalysts Supported on Activated Carbon for 1,2-Dichloroethane Abatement

Hydrothermal method is used to prepare activated carbon (AC) supported chromium-based catalysts for the catalytic combustion of 1,2-dichloroethane (DCE). The physicochemical properties relating catalysts are evaluated by several characterization techniques such as XRD, SEM, XPS, N2 adsorption-desorption isotherms, H2-TPR and NH3-TPR. The outcomes demonstrated that the Cr2O3 is the perfect targeted base catalyst adding to the facts that the hydrothermal approach is an appropriate way to create catalysts with superior properties. The textural characteristics, reducibility, and acidity of the Cr-based catalysts were all enhanced by the addition of cerium (Ce) and AC. Nevertheless, the research shows how crucial the Ce doping amount is for adjusting the physicochemical characteristics and catalytic efficacy of Cr-based catalysts. The catalyst 20Ce-Cr/AC has the maximum catalytic activity when it came to DCE combustion, where its T50 and T90 attaining of 247°C and 269.5°C, correspondingly. This is explained by the ideal Ce doping level, which improves the redox characteristics and revealed more active sites.

Ultrasonic-induced grafted lanthanum sulfide decorated multi-walled carbon nanotube onto bacterial cellulose applied for adsorption of pesticides in environmental waters

A new biosorbent was fabricated by modification of bacterial cellulose biopolymer grafted with lanthanum sulfide decorated carboxylated multiwall carbon nanotube (La2S3@MWCNT@BC). The sorbent was employed in a green alternative dispersive-solid phase extraction of a variety of 14 pesticides in environmental water samples. The analyses were performed using GC-µECD. The properties and structure of La2S3@MWCNT@BC nanocomposite were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and adsorption-desorption isotherms. The composition of the sorbent was also investigated to evaluate the adsorptive properties of its constituents. The impact of various parameters influencing extraction efficacies such as sorbent dose, adsorption time, sample pH, ionic strength, and desorption conditions was investigated. The method was validated by specificity, matrix effect % (-0.4 to -7.4), enrichment factor (4–10), limits of quantification (0.007–0.31 μg L−1), matrix-matched calibration linearity (0.01–200 µg L−1), determination coefficients (r2=0.9921–0.9998), and precision. The optimized method was applied for the analysis of multiclass pesticides in seven environmental and drinking waters and the recoveries were obtained in the 81–108 % range with RSDs of 2.5–4.7 %. This paper is the first report on the synthesis and use of La2S3@MWCNT@BC nanocomposite to extract pesticides from different water samples. The greenness of the procedure was evaluated by the AGREE protocols.

Efficacy of electrospun PAN/g-C3N4 nanofibers as a photocatalyst for the deterioration of hazardous azo dyes

PAN and PAN/g-C3N4 nanofibers were fabricated using the electrospinning technique. Meanwhile, g-C3N4 nanoflakes were synthesized using the thermal decomposition technique. The challenge of reusing powder catalysts was ultimately surmounted due to the use of dispersed g-C3N4. Characterization of the as-fabricated PAN/g-C3N4 NFs was performed employing wide-angle powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry (UV–Vis), thermogravimetry analysis (TGA), N2 adsorption-desorption isotherms (BET) and X-ray photoelectron spectrometer (XPS). According to morphological studies, g-C3N4 nanoflakes get uniformly decorated over PAN fibers with a greater specific surface area and smaller band gap than g-C3N4, exhibiting maximal uniformity in dispersion. Under solar light irradiation, PAN (71%), g-C3N4 (84%), and PAN/g-C3N4 nanofibers (95%) showed excellent photocatalytic performances for the degradation of Methyl orange dye (MO) in 120 min with 95% degradation. Similarly, PAN (61%), g-C3N4 (72%), and PAN/g-C3N4 nanofibers (91%) showed photocatalytic performances for the degradation of Congo red dye (CR) in 160 min with 91% degradation. This effective degradation was due to a shift in band gap with high porosity of PAN/g-C3N4 NFs compared to pure materials such as PAN and g-C3N4.

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.