Nitrogen Sorption Research Articles

The effect of porosity and particle size on the kinetics of porous carbon xerogels surface oxidation

Carbon surface oxidation was investigated to assess the effects of porosity and particle size on its course. Carbon xerogels that differed in porosity (micro-, micro-meso-, and micro-meso-macroporous materials) and particle size (from fine powders to monolithic cubes) were prepared. The prepared materials were characterized in detail with nitrogen sorption, SEM, and HRTEM. The oxidation of carbon xerogels was studied by isothermal thermogravimetry (TG) in an oxidizing atmosphere (50% O2 and 50% Ar). Isothermal TG experiments showed that the effects of particle size and porosity are interrelated and should be evaluated together as both significantly influence diffusion and heat transfer during carbon oxidation. On the basis of isothermal TG data, apparent kinetic parameters were determined assuming that carbon burn-off, the creation of oxygen surface groups, and the decomposition of created oxygen surface groups are reactions controlling the carbon surface oxidation. Detailed analysis of the obtained parameters proved that porosity and particle size do not affect the basic chemical reactions that occur on the carbon surface during oxidation.

Studies on the catalytic activities of ZSM-5 zeolites with different aluminum contents in the green oxidation of α-pinene to high value-added products

α-Pinene is the terpene abundant in nature. It is present in the oils of coniferous trees, mainly pine. We demonstrate that from this renewable stock, high value-added products such as verbenone, verbenol, α-pinene oxide, can be obtained as the main products, and smaller quantities of pinanediol carvone myrtenol pinocarveol campholenic aldehyde, myrtenal, and carveol are also produced. All the products have numerous applications in medicine, cosmetics, and foods. Heterogeneous ZSM-5 zeolite catalysts with different aluminum contents – designated as (in wt% of Al) ZSM-5_1 (2.5), ZSM-5_2 (0.59), and ZSM-5_3 (0.38) – were applied in the green α-pinene oxidation with oxygen and without solvent. To date, the use of the ZSM-5 catalyst in the α-pinene oxidation process has not been described. The catalysts were characterized by UV-Vis, FTIR, EDXRF, XRD, SEM, DTA techniques, and by the nitrogen sorption method at 77 K. The effects of catalyst amount and properties, temperature and reaction time, on product selectivity and α-pinene conversion, were determined.

Simultaneous removal of anionic and cationic dyes from wastewater with biosorbents from banana peels

AbstractUntreated banana peel (BP) is able to adsorb efficiently cationic dyes like methylene blue (MB) but weakly anionic dyes like orange G (OG). One way to enhance the sorption capacity for both dyes is to convert BP into activated carbon (BPAC) after thermochemical treatment. Among the various BPACs tested, the highest sorption capacity for both dyes was achieved when BP was modified with NaOH and pyrolyzed at 700°C (BPAC‐NaOH‐700). The pore structure of adsorbents was analyzed with scanning‐electron‐microscopy (SEM), nitrogen sorption isotherms, and mercury intrusion porosimetry (MIP), and the meso‐ and micro‐pore size distribution of BPAC‐NaOH‐700 was the narrowest one with the smallest mean value and the highest specific surface area. Equilibrium tests in batch mode were fitted with the extended Langmuir and Freundlich isotherms and used to estimate thermodynamic properties. The MB and OG sorption dynamics onto BPAC‐NaOH‐700 was approximated with the multi‐compartment model, and the external and internal mass‐transfer coefficients were estimated. The maximum sorption capacity of BPAC‐NaOH‐700 was found to be equal to 323 mg/g for MB and 76 mg/g for OG, both higher than the corresponding values for BP, and fully consistent with the high values of its surface area ( = 530 m2/g) and total pore volume ( = 1.81 cm3/g). The synergistic interaction for the sorption of both dyes onto BPAC‐NaOH‐700 was associated with a push‐pull mechanism, while the selective sorption of MB onto BPAC‐NaOH‐700 was attributed to the very slow rates of OG pore and surface diffusion in meso‐ and micro‐porosity, respectively. The adsorption was exothermic for BP, and endothermic for OG.

Composites of Lignin-Based Biochar with BiOCl for Photocatalytic Water Treatment: RSM Studies for Process Optimization

Textile effluents pose a massive threat to the aquatic environment, so, sustainable approaches for environmentally friendly multifunctional remediation methods degradation are still a challenge. In this study, composites consisting of bismuth oxyhalide nanoparticles, specifically bismuth oxychloride (BiOCl) nanoplatelets, and lignin-based biochar were synthesized following a one-step hydrolysis synthesis. The simultaneous photocatalytic and adsorptive remediation efficiency of the Biochar-BiOCl composites were studied for the removal of a benchmark azo anionic dye, methyl orange dye (MO). The influence of various parameters (such as catalyst dosage, initial dye concentration, and pH) on the photo-assisted removal was carried out and optimized using the Box-Behnken Design of RSM. The physicochemical properties of the nanomaterials were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, nitrogen sorption, and UV-Vis diffuse reflectance spectroscopy (DRS). The maximum dye removal was observed at a catalyst dosage of 1.39 g/L, an initial dye concentration of 41.8 mg/L, and a pH of 3.15. The experiment performed under optimized conditions resulted in 100% degradation of the MO after 60 min of light exposure. The incorporation of activated biochar had a positive impact on the photocatalytic performance of the BiOCl photocatalyst for removing the MO due to favorable changes in the surface morphology, optical absorption, and specific surface area and hence the dispersion of the photo-active nanoparticles leading to more photocatalytic active sites. This study is within the frames of the design and development of green-oriented nanomaterials of low cost for advanced (waste)water treatment applications.

Synthesis and Characterization of Hierarchical Zeolites Modified with Polysaccharides and Its Potential Role as a Platform for Drug Delivery.

Hierarchical zeolites are aluminosilicates with a crystal structure, which next to the micropores possess secondary porosity in the range of mesopores and/or small macropores. Due to their ordered structure and additional secondary porosity, they have aroused great interest among scientists in recent years. Therefore, the present work concerns the synthesis and characterization of hierarchical zeolites with secondary mesoporosity, based on commercial zeolites such as MFI (ZSM-5), BEA (β) and FAU (Y), and modified with polysaccharides such as inulin, hyaluronic acid, and heparin. All materials were characterized by various analytical techniques and applied as a platform for delivery of selected drug molecules. On the basis of X-ray diffraction (presence of reflections in the 2θ angle range of 1.5-2.5°) and low-temperature nitrogen sorption isotherms (mixture of isotherms of I and IV type) additional secondary porosity was found in the mesopore range. Additional tests were also conducted to determine the possibility of loading selected molecules with biological activity into the aforementioned materials and then releasing them in the therapeutic process. Molecules with different therapeutic options were selected for testing, namely ibuprofen, curcumin, and ferulic acid with anti-inflammatory, potentially anticancer, antioxidant, and skin discoloration activities, respectively. Preliminary studies have confirmed the possibility of using hierarchical zeolites as potential carriers for bioactive molecules, as the loading percentage of active substances ranged from 39-79% and cumulative release for ibuprofen reached almost 100% after 8 h of testing.

Collaborative Enhancement of Humidity Sensing Performance by KCl-Doped CuO/SnO2 p-n Heterostructures for Monitoring Human Activities.

In this study, a high-performance humidity sensor based on KCl-doped CuO/SnO2 p-n heterostructures was fabricated by a ball milling-roasting method. The morphology and nanostructure of the fabricated KCl-CuO/SnO2 composite were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen sorption analysis. The results showed that the humidity sensor had a high sensitivity of 194 kΩ/%RH, short response and recovery times of 1.0 and 1.5 s, a low hysteresis value, and good repeatability. The energy band structure and complex impedance spectrum of the KCl-CuO/SnO2 composite indicated that the excellent humidity sensing performance originated from the ionic conductivity of KCl, the formation of heterojunctions, the change in the Schottky barrier height, and the depletion of electronic depletion layers. The KCl-CuO/SnO2 sensor has great potential in respiratory monitoring, noncontact sensing of finger moisture, and environmental monitoring.

Conversion of Recovered Ammonia and Carbon Dioxide into Urea in the Presence of Catalytically Active Copper Species in Nanospaces of Porous Silica Hollow Spheres.

The present study firstly reported porous silica hollow spheres as a host material for recovery of ammonia and carbon dioxide and conversion of the compounds into urea. These compounds were effectively introduced into the hollow spheres from an aqueous solution including ammonium and carbonate ions accompanied with catalytically active copper ions from the analyses of diffuse reflectance infrared Fourier transform (DRIFT) spectra and diffusion reflectance ultraviolet-visible and near-infrared (DR UV-vis-NIR) spectra. The ammonium and carbonate ions were converted into urea in the hollow spheres at 323 K under 0.5 MPa of argon atmosphere from the results of the DRIFT spectra. From the results of nitrogen sorption isotherms and X-ray photoelectron spectra (XPS) spectra, the amount of the generated urea depended on the amount of the introduced ammonium ions and the size distribution of the nanospaces in the hollow spheres. Urea was highly generated in the hollow spheres with a high amount of ammonium ions and well-ordered nanospaces from the reactants at high density.

Anisole Hydrodeoxygenation over Nickel-Based Catalysts: Influences of Solvent and Support Properties

The realization of biofuels and chemicals requires the development of highly active and selective catalysts, which are resistant to deactivation. A conventional ZSM-5 (SiO2/Al2O3 = 30) was modified with 0.2 M NaOH to generate a mesoporous zeolite support. The parent zeolite, mic-ZSM-5, the modified zeolite, hie-ZSM-5, and a mesoporous silica support, SiO2, were impregnated with 5% nickel and characterized using X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis of nitrogen sorption, scanning electron microscopy with energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR), ammonium hydrogen temperature-programmed desorption (NH3-TPD), and thermogravimetric analysis (TGA). The influences of the support properties and solvent during the hydrodeoxygenation of anisole were investigated by measuring concentration profiles and rates in a high-pressure batch reactor. NaOH treatment significantly improved the pore structure, acidity of the support, and metal dispersion as well as the interaction of nonframework Ni species with zeolite and, hence, the catalytic activity and selectivity. The highest anisole conversion of 100% was obtained in 120 min over the hie-Ni/ZSM-5 catalyst with cyclohexane selectivity of 88.1%. In addition, the Ni/SiO2 catalyst was 84.5% selective to toluene at 48.9% anisole conversion in 120 min; as such, it was proposed that the transformation of anisole proceeds via either a direct deoxygenation–hydrogenation or isomerization–direct deoxygenation pathway. However, no substantial differences in anisole conversion or product selectivity were observed when decalin and n-decane were compared as solvents. A catalyst reusability test showed hie-Ni/ZSM-5 as the most stable of the three catalysts in terms of anisole transformation, even though the catalyst recorded the biggest weight loss of 9.2% suggesting high resistance to carbon deactivation. Therefore, with this very good catalytic activity, good selectivity to liquid product, and stability, the mesoporous Ni/ZSM-5 catalyst is a potential candidate for economically beneficial future industrial applications.

The anti SARS-CoV-2 activity of nanofibrous filter materials activated with metal clusters.

Nanofibrous filter materials were prepared by electrospinning a solution of 28wt% poly(vinylidene fluoride) in N,N-dimethylacetamide with and without the addition of 2wt% AgNO3, Cu(NO3)2·2.5H2O or ZnCl2. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectroscopy, thermogravimetric analysis, contact angle measurement, nitrogen sorption, and mercury intrusion porosimetry methods were used for the characterization of physical structure as well as the chemical composition of the electrospun materials. Particle filtration efficiency and antiviral activity against the SARS-CoV-2 alpha variant were tested in order to estimate the suitability of the prepared electrospun filter materials for application as indoor air filtration systems with virucidal properties. All filter materials prepared with salts demonstrated very high particle filtration efficiency (≥98.0%). The best antiviral activity was demonstrated by a material containing Cu(NO3)2·2.5H2O in the spinning solution, which displayed the decrease in the number of infectious virions by three orders of magnitude after a contact time of 12h. Materials with the addition of AgNO3 and ZnCl2 decreased the number of infectious virions after the same contact time by only ∼8 and ∼11 times, respectively.

Физико-химические характеристики нанокомпозитов Fe3O4/TiO2 и Fe3O4/SiO2/TiO2, синтезированных гид-ротермальным пероксидным методом

In the present paper the composite materials based on Fe3O4/TiO2 and Fe3O4/SiO2/TiO2 ox-ides, synthesized by the hydrothermal peroxide method, were studied. At the first stage, magnet-ite nanoparticles were precipitated by ammonium hydroxide from a mixture of aqueous solutions of iron(II) sulfate and iron(III) chloride under continuous exposure to ultrasound, after which they were washed with distilled water. At the second stage, the resulting hydrated magnetite particles were stabilized with polyvinyl alcohol (PVA) by dispersing them under the action of ultrasound in a hot saturated aqueous PVA solution. At the third stage, the photocatalytically active particles based on titanium oxide were introduced into the composite by mixing the stabilized magnetite suspension with an aqueous solution of peroxotitanic acid (optionally introducing a sol of silicic acid), followed by hydrothermal treatment of the mixture at 180°C for 24 hours, washing, and drying under vacuum followed by calcination in a muffle furnace. The effect of the molar content of iron and titanium on the properties of the samples, the introduction of silicon dioxide into them, as well as various calcination temperatures, were studied. The photocatalytic properties of the synthesized samples during photodegradation of methyl orange and methylene blue, as well as their magnetic recovery from suspension, were studied. The physicochemical characterization of the samples was performed using high-resolution scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, low-temperature nitrogen sorption porosimetry, inductively coupled plasma mass spectrometry, thermal analysis (TG–DSC), combined with mass spectrometry of gaseous thermolysis products. The optimal conditions for the synthesis of composites exhibiting the best combination of photocatalytic and magnetic properties were determined. The resulting photocatalysts can be used to purify water from dyes, followed by extraction using a magnet

Физико-химические и структурно-поверхностные свойства диоксида кремния, получаемого из минерального сырья

Samples of amorphous silicon dioxide (SiO2) were obtained by acid decomposition of mineral raw materials (nepheline). Their physico-chemical, acid-base and structural-surface properties have been studied by methods of chemical analysis, Parks, BET, BJH, etc. It was found that in terms of the content of impurities, the pH of the aqueous extract, the pH values of the isoionic point and the zero charge point, the SiO2 samples obtained are almost identical to pyrogenic amorphous silicon dioxide obtained from reactive raw materials (pharmaceutical preparation “Polysorb PM”) and have an increased specific external surface compared to “Polysorb PM” (in 1.1 – 1.9 times) and specific pore volume (1.4 times). Based on the obtained values of the specific capacity of the adsorption monolayer of the surface of SiO2 samples and the change in Gibbs energy (ΔG0) during sorption, it is concluded that the method of their preparation does not significantly affect the physicochemical properties of their surfaces and the mechanism of nitrogen sorption. Based on the results obtained, an assumption is made about the prospects of using silicon dioxide, obtained on the basis of acid processing of mineral raw materials, as an enterosorbent in therapeutic practice.

Cobalt decorated egg-shell-type activated carbon pellets: Catalytic application in hydrogen release from boron based solid fuel

Hydrogen became zero-carbon fuel used in fuel-cell or internal combustion engines, regard- ing energy sector green-hydrogen also has become an energy carrier in commercial appli- cations. For supporting decarbonization strategies based on hydrogen, boron-fuels are good options to safely store for mobile technologies. Ammonia borane (NH3BH3) is the one of the boron based fuels that stored 19.6 wt.% H2 in its structure chemically. Cobalt (Co) decorated egg-shell-type activated carbon pellets were synthesized for catalytic application of hydrogen release from NH3BH3. Two different sized pellet type activated carbon was decorated with co- balt by combined procedure as modified vacuum-impregnation method with heat fixation and reduction. The obtained catalysts were characterized by applying optical microscope (OM), scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS), transmis- sion electron microscopy (TEM), nitrogen sorption based surface analyses (BET). Activated carbon provides porous structure for effectively dispersion Co particles while the outer shell shows the catalytic activity for hydrogen generation. Structural characterization results and preliminary activity tests confirmed that fabricated Co@ACPB exhibited better performance compared with Co@ACPS catalysts thanks to thinner shell thickness and higher BET surface area/pore volume properties. The results of the kinetic study showed the core-shell type Co based catalyst catalyzed the reaction and follows the zero-order reaction kinetic model with 41.78 kJmol-1. Activated carbon pellets provide well dispersion and stability of active Co sites, easy separation of used catalysts after the reaction and enable practical regeneration of cata- lytic materials.

Solvothermal Synthesis of g-C3N4/TiO2 Hybrid Photocatalyst with a Broaden Activation Spectrum

A solvothermal self-made composite of graphitic carbon nitride (g-C3N4) and commercially available titanium dioxide (TiO2) demonstrated the removal of commercial acid green-25 (AG-25) textile dye in a saline water matrix when activated by ultraviolet (UV) and visible light. The g-C3N4-TiO2 composite was characterized by X-ray diffraction (XRD), Nitrogen sorption–desorption recording and modeling by the Brunauer–Emmett–Teller (BET) theory, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electron spin resonance (ESR). The solvothermal process did not modify the crystalline structure of the g-C3N4 and TiO2 but enhanced the surface area by interlayer delamination of g-C3N4. Under a simulated solar spectrum (including UVA/B and vis wavelengths), the degradation rate of AG-25 by the composite was two and four times higher than that of TiO2 and pure g-C3N4, respectively (0.04, 0.02, and 0.01 min−1). Unlike TiO2, the g-C3N4-TiO2 composite was activated with visible light (the UV portion of the solar spectrum was filtered out). This work provides insight into the contribution of various reactive oxidative species (ROS) to the degradation of AG-25 by the composite.

Electrocatalytic Performance of Nickel Hydroxide-Decorated Microporous Nanozeolite Beta-Modified Carbon Paste Electrode for Formaldehyde Oxidation

In this paper, aluminosilicate nanozeolite beta has been prepared and described using X-ray diffraction (XRD), nitrogen sorption isotherm, Fourier transform infrared (FT-IR), transmission electron micrograph (TEM), and field emission scanning electronic microscopy (FESEM) techniques; TEM image demonstrated semispherical particles with dimensions under 50 nm. The BET surface area, total pore volume, and pore diameter of it were attained to be 321 m2 g−1, 0.053 cm3 g−1, and 1.22 nm, respectively. The modified carbon paste electrode by aluminosilicate nanozeolite beta and nickel hydroxide (Ni(OH)2-Beta/CPE) was applied for formaldehyde (HCHO) electrocatalytic oxidation. The obtained results specify that Ni(OH)2-Beta/CPE demonstrates worthy electrocatalytic activity for oxidation of HCHO due to mesoporous construction and the great surface area of nanozeolite. The electron-transfer coefficient, catalytic rate constant, and diffusion coefficient are found to be 0.69, 2.08 × 106 cm3 mol−1 s−1, and 4.4 × 10−7 cm2 s−1, respectively. The Ni(OH)2-Beta/CPE exhibited low background current, simplicity of surface renewal, good reproducibility, and stability and also displayed high stability up to 300 cycles and 3000 s without an important loss in the current density. This modified electrode has better poisoning tolerance capability than bare CPE for HCHO electrocatalytic oxidation and is a higher device for the long term accomplishment.

Selective recovery of Gd(III) by benzimidazole- and benzoxazole-linked 3D porous polymers

Three-dimensional porous benzimidazole- and benzoxazole- linked polymers were successfully prepared through a one-pot method using benzol-1,2,4,5-tetramintetrahydrochlorid (BTD) and 2,5-diamino-1,4-benzediol dihydrochloride (DBD) to react with 4-[tris(4-formyl phenyl)methyl]benzaldehyde (TFPM), respectively. According to nitrogen sorption analysis, TFPM-BTD and TFPM-DBD possessed specific surface areas of 612.60 and 524.90 m2/g, and the total pore volumes (Vtot) of 1.44 and 1.15 cm3/g, respectively. Batch adsorption experiments demonstrated that Gd(III) adsorption processes by TFPM-BTD and TFPM-DBD fit well with the Langmuir isotherm and the pseudo-second-order kinetic model. At 25 °C and pH level of 6, TFPM-BTD showed a much higher adsorption capacity for Gd(III), detected at 173 mg/g, as opposed to TFPM-DBD at 82 mg/g. Associated spectra of N 1s via high-resolution X-ray photoelectron spectroscopy (XPS) revealed the generation of coordination bonds between Gd(III) and (-NH-) of TFPM-BTD polymer during Gd(III) adsorption, while Energy-dispersive X-ray spectroscopy (EDS) analysis proved the uniform adsorption of Gd(III) on TFPM-BTD. TFPM-BTD showed high selectivity toward the adsorption of heavy rare earth ions, in a high-to-low order of Gd3+>Ce3+>Er3+>La3+>Ni2+>Mg2+>Zn2+. Furthermore, TFPM-BTD exhibited excellent cycling stability and regeneration performance. Gd(III) adsorption capacity of TFPM-BTD after five adsorption/elution cycles was retained at 63.9 %. The elution efficiency was extremely high when using 0.1 mol/L hydrochloric acid as the eluent, showing an average five-cycle desorption efficiency over 95 %. The outcomes will provide theoretical and practical guidance to develop high-performance and selective adsorbents for efficient removal of heavy rare earth ions from water.

Mesoporous Silica Nanoparticles for pH-Responsive Delivery of Iridium Metallotherapeutics and Treatment of Glioblastoma Multiforme

Using nanoparticles for controlled drug delivery to cancer, in response to its weakly acidic environment, represents a promising approach toward increasing the effectiveness and reducing the adverse effects of cancer therapy. Hence, the aim of this study is to construct novel mesoporous silica nanoparticle (MSN)-based acidification-responsive drug delivery systems for targeted cancer therapy. Herein, the surface of MSN is covalently functionalized with Ir(III)-based complex through a pH-cleavable hydrazone-based linker and characterized by nitrogen sorption, SEM, FTIR, EDS, TGA, DSC, DLS, and zeta potential measurements. Enhanced release of Ir(III)-complexes is evidenced by UV/VIS spectroscopy at the weakly acidic environments (pH 5 and pH 6) in comparison to the release at physiological conditions. The in vitro toxicity of the prepared materials is tested on healthy MRC-5 cells while their potential for the efficient treatment of glioblastoma multiforme is demonstrated on the U251 cell line.

Can high temperature calcined Mg–Al layered double hydroxides (LDHs) fully rehydrate at room temperature in vapor or liquid condition?

The rehydration behavior of metal oxides (LDOs) derived from calcination of Mg–Al layered double hydroxides (LDHs) at high temperatures of 600–900 °C was studied in the presence of deionized water under vapor or liquid conditions. XRD reflections showed that the LDO metal oxides obtained from thermally treated LDHs can rehydrate into LDHs at room temperature even after calcination as high as 900 °C, both in vapor and liquid conditions, although faster in the latter. Only when the calcination temperature was increased to 900 °C an additional spinel phase appeared, which remained in the particles under both vapor and liquid rehydration conditions. This is proven by 27Al MAS NMR showing the presence of a peak representing tetrahedral Al. Differences between the as-synthesized LDHs and rehydrated LDOs were observed via additional analysis with FTIR, SEM and nitrogen sorption. This illustrated that the process of the rehydration of the LDO into the LDH resulted in a new LDH rather than reconstructing it into the former LDH. Based on the results, it is suggested that even after high temperature calcination (600–900 °C), samples need to be stored carefully to avoid rehydration reactions to altered LDH materials, occurring at room temperature under ambient, moist containing atmosphere.

Molybdenum Incorporated Strontium‐Iron and Strontium‐Cobalt (SrBMoO3−δ; B=Fe & Co) Perovskites: Preparation and Their Application on Oxidation of Iso‐Eugenol into Vanillin

AbstractSrBO3−δ (B=Fe & Co) type perovskite oxides and their 25 % molybdenum doped counterparts, SrFe0.75Mo0.25O3−δ (SFMO) and SrCo0.75Mo0.25O3−δ (SFCO) are synthesized by the conventional solid‐state method and systematically characterized using Fourier transfer infrared spectroscopy, powder X‐ray diffraction, thermo‐gravimetric analysis, nitrogen sorption, and temperature‐programmed reduction. The powder X‐ray diffraction patterns and FTIR spectral analysis evident the formation of the pure cubic phase and the doping of molybdenum into the perovskite crystal lattice. The variable oxidation states of iron and cobalt and the formation of oxygen vacancies are apparent from the TPR‐H2 and TGA curves, respectively. All of the samples have a lower surface area than porous materials, which is typical of the bulk oxide character. The iron‐based perovskite demonstrated superior activity to the cobalt‐based one for the oxidation of iso‐eugenol to 4‐hydroxy‐3‐methoxybenzaldehyde (vanillin) when employing aqueous H2O2 as the oxidant. The maximum conversion of 73 % with 63 % selectivity for vanillin was obtained within 1.5 h at 60 °C over the SFMO catalyst. The catalytic conversion was almost similar upon re‐use of the catalyst.

Removal of Phenanthrene from wastewater with low-cost adsorbents

The potential to remove Phenanthrene (PHE) from water matrices through adsorption onto natural organic substances (NOSs) and natural inorganic compounds (NICs) was studied. Coffee waste (CW) and activated carbon (AC) produced from CW, and chemically pre-treated with NaOH or H3PO4 were chosen as NOS, and diatomaceous earth (DE) and DE pre-treated with NaOH or H3PO4 was chosen as NIC. Comparative analysis showed that the AC produced from CW pre-treated with NaOH and pyrolyzed at 800 °C (CWAC-NaOH-800) was the most efficient adsorbent, and used for parametric analysis with respect to the initial pH of the solution, the contact time, and initial PHE concentration. The pore structure parameters of adsorbents were determined from nitrogen sorption isotherms. The pseudo-second-order kinetic model was fitted better to the experimental data, showing that chemisorption is the rate-controlling step in the adsorption process. Sips isotherm gave the best fit to the experimental isotherm data indicating that adsorption occurs on a heterogenous system, and adsorption capacity was found qmax = 143.85 mg/g. The results show that CWAC-NaOH-800 with the highest specific surface area (SSA=910 m2/g) is very efficient toward the adsorption of PHE which makes it a well-promising material for the removal of PAHs from waters.

Adsorptive Remediation of Hazardous Crystal Violet Dye using Ni1‐xZnxFe2O4 Magnetic Nanocomposites

AbstractCrystal violet (CV) dye is one of the most poisonous colors primarily produced in the textile industry. In the current study, the co‐precipitation assisted ultrasonic radiation method was used to synthesized Ni1‐xZnxFe2O4 magnetic nanoparticles for the CV dye removal from aqueous solutions. The adsorbents were characterized by vibrating specimen magnetometer (VSM), X‐ray diffraction (XRD), High resolution transmission electron microscope (HRTEM), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and nitrogen sorption analysis. XRD confirmed the successful synthesis of Ni1‐xZnxFe2O4 single phase with a characteristic diffraction (311) peak at 2θ=35.5°. XPS analysis proved the successful substitution of Ni2+ by Zn2+ ions in the spinel structure. N2 sorption revealed that, the prepared adsorbent exhibited a mesoporous structure of slit shaped and narrow entrances, especially at high annealing temperatures. Results revealed that the magnetic Ni0.1Zn0.9Fe2O4 nano adsorbent offered a maximum adsorption capacity of 473.9 mg g−1 at pH 10.0, which is significantly greater than that of the other noted for CV removal. In addition, ferromagnetic nature was observed by Ni0.5Zn0.5Fe2O4 with a saturation magnetization value of 60.1 emg/g. Equilibrium and kinetic studies demonstrated that, the adsorption is of chemical nature and controlled with pore and film diffusion. Finally, we concluded that Ni1‐xZnxFe2O4 can be utilized as a potential magnetic composite for the purification of CV contaminated water.