Nitrogen Adsorption-desorption Analysis Research Articles

Mesoporous titania as sorbent for 99Mo/99mTc generators column with low specific activity molybdenum-99 for nuclear medicine application

Abstract The 99Mo/99mTc generator is a chromatography column system that can be eluted to obtain technetium-99m (99mTc) for nuclear medicine applications in the hospital. Mesoporous titania is developed for the Mo adsorbent of a 99Mo/99mTc generator column employing low specific activity 99Mo produced by nuclear reactor irradiation of natural molybdenum. A symmetric triblock copolymer of P123 was used as a template to create mesoporous titania using the sol-gel process.. The molar ratio of the reactant (titanium tetraisopropoxide (TTIP) and titanium chloride (TiCl4)) was applied with ratios 1:1 and 3:2. Then, the different temperature calcination also was implied at 450 °C and 550 °C. The resulting mesoporous titania was studied utilizing thermal gravimetry analysis (TGA), nitrogen adsorption-desorption, and characterization analysis of X-ray diffraction. Furthermore, the Mo adsorption test was conducted by batch method. The highest molybdenum adsorption capacity of mesoporous titania samples is 34.62 mg Mo g−1 adsorbent. Mesoporous titania has the potential as a novel adsorbent for the 99Mo/99mTc generator column.

Enhanced super-ultra-deep photocatalytic oxidative desulfurization by titanium-activated metal-organic frameworks nanophotocataltyst

Addressing the escalating global demand for fossil fuels and the urgent environmental concerns associated with their use necessitates the development and implementation of efficient and cost-effective techniques for the removal of sulfur compounds. In this study, titanium-activated MIL-101(Fe) was utilized for the removal of organosulfur compounds through the photocatalytic oxidation desulfurization (PODS) process. The coexistence of active sites with titanium and iron resulted in an ultra-deep desulfurization. The impact of titanium loading was assessed, with TxML representing the ratio of Ti to Fe (x = 1, 1.5, and 2, respectively). Nanophotocatalysts were fabricated by solvothermal method. The physicochemical properties of the new materials were investigated by performing XRD, TEM, FT-IR, FESEM, EDX, UV–Vis DRS, PL, GC–MS, ESR, TGA, transient photocurrent, and nitrogen adsorption–desorption analyses. The effect of titanium loading on the structure, and performance of photocatalysts in the PODS reaction was investigated. The reaction parameters were optimized for maximum efficiency. Under optimal conditions of T2ML loading at 1.5 g/L, a volumetric solvent to fuel ratio (S/F) of 1, and a temperature of 50 ℃, T2ML shows the best performance by removing 100 % of dibenzothiophene.Kinetic experiments revealed that the PODS reaction obeys a pseudo-first order equation, and activation energy is 47.08 kJ.mol−1.

Investigation of the Effects of Waste Olive Pomace on Vermicompost

The effects of olive pomace on the degradation of organic matter were investigated via vermicomposting. Biomass consisting of eggshell, cabbage, banana peel, napkin, nutshell, cattle manure, and soil was amended with varying amounts of olive pomace (0, 15, 30, 37.5%). These four mixtures, with a total of 2000g, were fed to 170 Eisenia fetida earthworms per mixture. Nitrogen adsorption-desorption, FT-IR, and elemental analyses analyzed samples collected from biomass at the end of 45 days. Results were evaluated to determine the effect of olive pomace on organic matter degradation and earthworm vitality. Nitrogen adsorption-desorption isotherms of feedstock revealed a decrease in void volumes, implying the formation of a compact structure with olive pomace addition. Vermicomposting of biomass enhanced biomass’s compactness, further validated by decreases in BET surface areas, pore sizes, and pore volumes. The 31% increase of earthworm biomass in the presence of 37.5% olive pomace implied an affinity of Eisenia fetida towards olive pomace. This finding was further validated by FT-IR peaks obtained at 2850 and 2923 cm-1, showing increased biomass aromaticity due to the degradation of readily biodegradable aliphatic structure introduced by olive pomace. Ongoing organic matter degradation could be observed with the decrease of C/N ratios in the presence of olive pomace as high as 15%. However, a further increase in olive pomace increased the C/N ratio, which was explained by the increase in total nitrogen values during vermicomposting. Elemental analyses evaluated regarding C/N, O/C, and H/C ratios also indicated increased earthworm mobility with increasing olive pomace in the feedstock. The results obtained in the study were interpreted to introduce olive pomace as a preferable nutrition source for earthworms, which was the highlight of the present study

Fabrication of magnetic functionalized layered double hydroxide nanomaterials for detecting trace fluoroquinolones residues in meat integrated with HPLC-MS/MS

Fluoroquinolones (FQs) are widely used to treat various animal diseases. The high residue of veterinary drugs in animal-origin food are new pollutants that seriously threaten human health. In this work, Fe3O4@LDH/ZIF was prepared by the in situ growth of zeolitic imidazolium skeletons (ZIFs) on Fe3O4@Zn/Al-layered double hydroxides (Fe3O4@Zn/Al-LDH), which was used as the adsorbent of FQs for magnetic solid phase extraction (MSPE). The prepared materials were characterized by using FT-IR, XRD, TEM, SEM, VSM, zeta, and nitrogen adsorption-desorption analyses. Under the optimized conditions, the limit of detections (LODs) of proposed methods for FQs is determined as low as 0.1–0.6 μg·kg−1 with good linearity (R2≥0.9972). Furthermore, the MSPE approach has been effectively utilized to extract of FQs from a range of meat varieties including fish, pork, chicken, bullfrog, and beef. The recoveries from the spiked samples ranged from 86.5 % to 107 %, with relative standard deviations (RSD) below 8.8 %. These results demonstrated that the prepared nanoparticles hold unique advantages for trace FQs analysis in foodstuffs. This study provides a magnetic adsorbent for food sample pretreatment, which can rapidly enrich compounds similar in structure to fluoroquinolones.

Impact of Weak Organic Acids as Coagulants on Tailoring the Properties of Cellulose Aerogel Beads.

Tailoring the properties of cellulose aerogel beads was investigated in the present study by using weak organic acids as coagulants. Three different weak acids were specifically chosen, acetic acid, lactic acid and citric acid. For comparative studies, a strong acid, hydrochloric acid was examined. The production of aerogel beads by conventional dropping technique was controlled and optimized for weak acids. Aerogels were characterized by density analyses, scanning electron microscopy, nitrogen adsorption-desorption analysis, X-ray powder diffractometry and IR spectroscopy. In common, all the aerogel beads showed interconnected nanofibrillar network, high specific surface area, high pore volume, high porosity and meso- and macroporous structure. In particular, when the weakest acid (acetic acid) was used as coagulant in the regeneration bath, the lowest shrinkage was observed. As a result, the cellulose aerogel beads produced from acetic acid showed the highest values of specific surface area (423 m2 g-1) and pore volume (3.6 cm3 g-1). The porous structure can be tuned by the choice of regeneration bath, which has either strong acid or a high concentration of weak acid. The aerogel beads were pure and showed cellulose II crystallinity. Hence this study paves an alternative path way to tailor the properties of cellulose aerogel beads.

Physico-chemical characteristics of Ca/P ratio on the composition and structure of oxygenated apatite

Phosphocalcic apatites have osteoconductive and bioactive properties that make them suitable for bone reconstruction. But, they are inactive against pathogenic microorganisms that can infect bone tissue. To overcome this limitation, we synthesized oxygen-doped phosphocalcic apatites that can release molecular oxygen as a bioactive molecule. We investigated how the calcium-to-phosphorus ratio (Ca/P) gave impacts on the chemical and structural composition of the oxygen-doped phosphocalcic apatites. We here used the double decomposition method, which involved mixing calcium nitrate and diammonium phosphate solutions in an ammonia buffer. We then characterized the products using several analysis, including infrared absorption spectroscopy, X-ray diffraction, thermal analysis, nitrogen adsorption-desorption, and elemental chemical analysis. It was found that the oxygen-doped phosphocalcic apatites were calcium-deficient and had a well-defined crystallinity at room temperature. After calcination at 900°C, the crystallinity improved further. The thermal analysis showed two mass losses: one at 50°C due to water adsorption and another at 450°C due to CO2 release. The specific surface area was about 100 ± 2 m2/g without any change with the Ca/P ratio. The quantity of molecular oxygen increased with the Ca/P ratio and reached an optimal value of the order of 3.6 ×10-4 mol for Ca/P=1/65 with the chemical formula of Ca9.9(PO4)6(OH)1.25(O2)0.74(CO3)0.01. It is important to make further analysis to know more about the properties of oxygenated apatite, and to combine this apatite with polymers purposely to have biomedical composites. It then can be concluded that the oxygen-doped phosphocalcic apatites could be a promising biomaterial for bone infection prevention and treatment. This research highlights an oxygenation treatment of phosphocalcic apatite and brings new ideas and possibilities for future research and development to get better understanding of the behavior of these biomaterials to be more effective, especially in the biological field. As a perspective, improving the biological properties in these biomaterials needs to be further explored, including experimental parameters for the obtainment of more conclusive results.

Identification of suitable catalyst among HZSM-5, HY and γ-Al2O3 to obtain upgraded pyrolysis oil with augmented liquid oil yield

This study examines catalytic ability of various zeolite materials in converting discarded tire pyrolyzed oil by employing a moderate sized pyrolysis plant of a 10 L working volume. The study revealed that the yield of liquid fractions using γ-Al2O3 was greater than that of HZSM-5 and HY, while the yield of condensates were limited in the absence of catalyst. The tire waste pyrolysis oil catalytcially enhanced by alumina catalyst analyzed using Fourier transform infrared spectroscopy exhibited the stretching bands corresponding to aromatic and non-aromatic compounds. The GC MS analysis revealed that the cyclic unsaturated fragment percentages in liquids were decreased by the catalysts to 53.9% with HY, 59.0% with γ-Al2O3, and 62.2% with HZSM-5, which in turn was converted into aromatic chemicals. Nitrogen adsorption desorption analysis revealed that γ-Al2O3 has an enhanced surface area of 635 m2/g which improved its catalytic performance. The cracked liquid oil had viscosity (10.36 cSt), values of pour and flash temperatures of −2.2 °C and 41 °C respectively, analogous to petroleum diesel. The upgraded pyrolysis oil (10%) is blended with gasoline (90%), and emission analysis was performed. Moreover, liquid oil needs post treatment (refining) for its use as energy source in transportation application. The novelty of this research is in its comparative analysis of multiple catalysts under controlled conditions using a small pilot-scale pyrolysis reactor, which provides insights into optimizing the pyrolysis process for industrial applications.

Versatile Activated Carbon Fibers Derived from the Cotton Fibers Used as CO2 Solid-State Adsorbents and Electrode Materials.

Activated carbon has an excellent porous structure and is considered a promising adsorbent and electrode material. In this study, activated carbon fibers (ACFs) with abundant microporous structures, derived from natural cotton fibers, were successfully synthesized at a certain temperature in an Ar atmosphere and then activated with KOH. The obtained ACFs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analysis, nitrogen and carbon dioxide adsorption-desorption analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N2 adsorption-desorption measurement. The obtained ACFs showed high porous qualities and had a surface area from 673 to 1597 m2/g and a pore volume from 0.33 to 0.79 cm3/g. The CO2 capture capacities of prepared ACFs were measured and the maximum capture capacity for CO2 up to 6.9 mmol/g or 4.6 mmol/g could be achieved at 0 °C or 25 °C and 1 standard atmospheric pressure (1 atm). Furthermore, the electrochemical capacitive properties of as-prepared ACFs in KOH aqueous electrolyte were also studied. It is important to note that the pore volume of the pores below 0.90 nm plays key roles to determine both the CO2 capture ability and the electrochemical capacitance. This study provides guidance for designing porous carbon materials with high CO2 capture capacity or excellent capacitance performance.

CuO/NiO nanocomposite prepared with Saussurea costus extract for super-capacitor energy storage application

This work reports a green synthesis of CuO/NiO nanocomposite with different CuO/NiO ratios. The X-ray diffraction (XRD) confirmed the existence of both CuO and NiO. This was also confirmed by energy dispersive X-ray (EDX). Scanning electron microscopy (SEM) reveals that changing the compositions of the nanocomposites resulted in different surface morphologies with different particle shapes, sizes, and levels of aggregation. Nitrogen adsorption-desorption analysis showed microporous structures with pore size in the range of 1.66-1.75 nm and surface area in the range of 82-513 m2g−1. The supercapacitive activity was examined by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The results display that the 1C3N exhibited the highest capacitive performance of 1072 Fg−1 compared to 760, 716, and 260 Fg−1 for 3C1N, 4 N, and 4 C, respectively. Furthermore, the 1C3N electrode shows a cyclic stability of 72% after 4000 cycles, which makes it a promising candidate for supercapacitive applications.

Engineered biochar-based catalytic pyrolysis of Spirulina plantensis microalgae for the production of high value compounds in microwave reactor

Energy demands are continually increasing as a result of population growth and industrialization, prompting the completion of new research to examine biochar-based catalytic pyrolysis of Spirulina plantensis (SP) microalgae for the generation of high-value chemicals in a microwave reactor. Biochar-based catalysts have excellent microwave absorption, a porous structure, and high catalytic activity, making them ideal for microwave-induced biomass pyrolysis. Initially, raw biomass, biochar, and Zn-BC were characterized based on XRD, FTIR, nitrogen adsorption-desorption and SEM-EDS analysis to determine the phases, functional groups, BET surface area and morphology, respectively. The thermogravimetric analysis results demonstrated the favourable impact of Zn-BC by displaying a drop in the reaction's temperature requirements. The kinetic study revealed that catalytic pyrolysis has a lower activation energy (27.62 kJ/mol) than non-catalytic pyrolysis (32.99 kJ/mol). FTIR measurement of the bio-oil indicated that at particular peak positions, intensity has changed or disappeared. The GCMS results revealed a significant reduction in the nitrogen-containing (19 %) chemicals at the same time increase in acidic chemicals for the catalytic bio-oil.

Novel granular bentonite-carbon sorbents: textural characterization, adsorption-desorption isotherm, kinetics, and cost estimation.

This research focuses on the synthesis of novel low-cost granular sorbents based on bentonite clay of the Navbahor deposit, dust fraction of Angren brown coal, and agricultural wastes such as straw and sawdust to meet the internal needs of the Republic of Uzbekistan. The impact of the initial mixture ingredients on the structural and textural properties of bentonite-coal sorbents (BCSs) has been studied using X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, optical microscopy, and nitrogen adsorption-desorption analysis. For determining the sorption capacity of BCSs, a standard model substance methylene blue (MB), was applied. It was revealed that the maximum adsorption amount of MB was 5.3 mg∙g-1 during 2 h of contact. Prolonging the contact time to 24 h allowed for more extensive diffusion of dye molecules into the sorbent's pores, increasing the adsorption capacity to 13 mg∙g-1. It was demonstrated that BCSs could be regenerated by strong oxidizing agents such as sulfuric acid and hydrogen peroxide, with sulfuric acid proving more effective. Regeneration fully restores sorption properties, particularly at low dye concentrations (up to 0.2 mg∙ml-1). Despite slight reductions in adsorption capacity over multiple regeneration cycles, the sorbents maintain their structural integrity and durability. It is shown that compared to imported expensive activated carbon, the gross profitability of the in-house production of such granular BCSs within the territory of Uzbekistan increases from 48 to 78%, while the net income increases almost three times.

Magnetic dispersive solid-phase extraction of clarithromycin and azithromycin by Fe3O4@ionic salt g-C3N4 adsorbent and HPLC-UV

In this study, Fe3O4@ionic salt g-C3N4 was synthesized as a new adsorbent for magnetic dispersive solid phase extraction (MDSPE) of two antibiotics (clarithromycin and azithromycin) in biological samples followed by HPLC-UV. The new nanocomposite was characterized by Fourier-transform infrared (FT-IR), field emission-scanning electronic microscope (FE-SEM), transmission electron microscope (TEM), nitrogen adsorption–desorption analysis, X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Box-Behnken design (BBD) and response surface methodology (RSM) were used for the optimization and design of experiments. The method had a suitable linear range (1–300 µg/L), a high coefficient of determination (R2; 0.9988 and 0.9993), and a low detection limit (0.33 and 0.42 µg/L) for clarithromycin and azithromycin, respectively. The applicability of the method was evaluated by estimating the recovery of analytes from urine and blood serum samples. Recovery of more than 90.0 % and RSDs of less than 5.2 % show the acceptable accuracy and precision of the proposed method.

Sustainable synthesis of spongy-like porous carbon for supercapacitive energy storage systems towards pollution control.

In this study, the fruit of Terminalia chebula, commonly known as chebulic myrobalan, is used as the precursor for carbon for its application in supercapacitors. The Terminalia chebula biomass-derived sponge-like porous carbon (TC-SPC) is synthesized using a facile and economical method of pyrolysis. TC-SPC thus obtained is subjected to XRD, FESEM, TEM, HRTEM, XPS, Raman spectroscopy, ATR-FTIR, and nitrogen adsorption-desorption analyses for their structural and chemical composition. The examination revealed that TC-SPC has a crystalline nature and a mesoporous and microporous structure accompanied by a disordered carbon framework that is doped with heteroatoms such as nitrogen and sulfur. Electrochemical studies are performed on TC-SPC using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. TC-SPC contributed a maximum specific capacitance of 145 F g-1 obtained at 1 A g-1. The cyclic stability of TC-SPC is significant with 10,000 cycles, maintaining the capacitance retention value of 96%. The results demonstrated that by turning the fruit of Terminalia chebula into an opulent product, a supercapacitor, TC-SPC generated from biomass has proven to be a potential candidate for energy storage application.

Facile encapsulation of a cobalt complex inside the micropores of ZIF-8 through the bottle around the ship method: A novel heterogeneous catalyst for epoxidation of alkenes

A novel and stable heterogeneous catalyst for alkene epoxidation reaction, named as CoDMG@ZIF-8, has been synthesized by facile encapsulation of Co(III) complex i.e. [Co(DMGH)(DMGH2)Cl2] (abbreviated as CoDMG, DMGH2 denotes for dimethylglyoxime and DMGH denotes for dimethylglyoxime mono anion) inside the ZIF-8 micropores via a solvothermal process. Based on the results of fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) technique and field emission scanning electron microscopy (FE-SEM), it was observed that the catalyst has maintained the structure, crystallinity and morphology of the parent ZIF-8 as well. Furthermore, CHN, DRS (diffuse reflectance spectra), energy dispersive X-ray (EDX), induced coupled plasma (ICP-OES), thermal gravimetric (TGA) and nitrogen adsorption-desorption (BET method) analyses have confirmed the encapsulation of the CoDMG complex. The epoxidation reaction was performed using tert‑butyl hydroperoxide (TBHP) in CH3CN solvent in the presence of catalyst. By optimizing the reaction parameters, a total conversion of 96 % with 82 % selectivity towards the epoxide product, was achieved. It was found that both CoDMG complex and ZIF-8 exhibited lower efficiency individually, while the encapsulation of this complex inside the ZIF-8 micropores has resulted to superior activity. Finally, the epoxidation of various alkenes such as cyclohexene, 2-norbornene, α-pinene, styrene and 1-hexene under the optimized reaction condition, have been studied and the catalytic mechanism was also proposed.

Engineering acidic and Pt sites on WO3- doped H-mordenite supported Pt catalyst for hydrogenation of γ -valerolactone to methyl tetra hydrofuran

The selective hydrogenation of gamma valerolactone (herein after GVL) into 2-methyl tetra hydrofuran (herein after MTHF) was studied over the different tungsten oxide-loaded Pt-doped H-Mordenite catalysts in a vapour phase continuous flow reactor. These catalysts were characterized by XRD, N2 adsorption-desorption analysis, SEM, TEM, FT-IR, Raman, XPS, TPR, NH3-TPD and pyridine adsorbed FT-IR analysis. XRD analysis result suggests that the tungsten oxide was well dispersed at low tungsten oxide loadings and, the tungsten oxide crystallites were formed at higher tungsten oxide loadings and the crystalline structure related to H-mordenite was retained for all the synthesised samples. The nitrogen adsorption-desorption analysis supported this result well. The TEM analysis confirms nano-sized platinum and tungsten oxide formation at 2Pt/10W-HM samples. The ammonia TPD analysis results suggested that all the samples possess weak and strong acidic sites and the amount and strength of acidic sites varies among the samples. The Pyridine adsorbed FT-IR results suggested that all the sample possesses mainly lewis acidic sites. These catalysts were evaluated for synthesising MTHF from GVL under different reaction conditions. Among the various synthesised catalysts studied, the 2 wt% Pt/10W-HM catalyst was identified as an effective catalyst with the 97 % conversion of GVL and the 98 % selectivity of MTHF. The higher catalytic performance depended on the distribution of surface tungsten oxide species along with the suitable acidic properties of the supported system.

A Magnetic Reduced Graphene Oxide Nanocomposite: Synthesis, Characterization, and Application for High-Efficiency Detoxification of Aflatoxin B1.

(1) Background: Safety problems associated with aflatoxin B1 (AFB1) contamination have always been a major threat to human health. Removing AFB1 through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB1 adsorption efficiency, a magnetic reduced graphene oxide composite (Fe3O4@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption-desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe3O4@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe3O4 nanoparticles. The results of various characterizations illustrated that the surface of Fe3O4@rGO had a two-dimensional layered nanostructure with many folds and that Fe3O4 nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB1 by Fe3O4@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g-1; the rapid and efficient adsorption of AFB1 occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe3O4@rGO, with favorable properties for AFB1 adsorption and potential for food safety applications.

Effect of calcination temperature of titanium dioxide (TiO2) on adsorption performance of doxycycline hydrochloride

In this work, titanium dioxide (TiO2) was synthesized at different calcination temperatures by sol-gel method using butyl titanate as raw material. The effect of calcination temperature on the crystallinity and adsorption properties of TiO2 were investigated at 300 °C, 450 °C and 600 °C, respectively. The characteristics of TiO2 were analysed by X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption-desorption analyzer and zeta potential tester. The results showed that the crystal type, specific surface area and zeta potential of TiO2 nanoparticles changed with the increase of calcination temperature and the best performance of anatase crystals happened at the calcination temperature of 300 °C (TiO2@300) for doxycycline hydrochloride (DCH) adsorption. The equilibrium adsorption capacities of DCH was 28.97 mg/g with DCH removal rate of 86.92% at 0.03 g TiO2@300 addition in 100 ml 10 mg/L DCH solution. TiO2@300 could be a promising adsorbent.

Dual-functional porphyrinic zirconium-based metal-organic framework for the fluorescent sensing of histidine enantiomers and Hg2.

A novel fluorescence sensor based on a porphyrinic zirconium-based metal-organic framework, L-cysteine-modified PCN-222 (L-Cys/PCN-222), was developed to selectively recognize histidine enantiomers and sensitively detect Hg2+. The dual-functional sensor was successfully prepared via the solvent-assisted ligand incorporation method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption analyses. L-Cys/PCN-222 not only showed a higher quenching response for L-histidine than that for D-histidine with a fast fluorescent response rate of <40 s but also exhibited low detection limits for L- and D-histidine (2.48 μmol L-1 and 3.85 μmol L-1, respectively). Moreover, L-Cys/PCN-222 was employed as a fluorescent and visual sensor for the highly sensitive detection of Hg2+ in the linear range of 10-500 μmol L-1, and the detection limit was calculated to be 2.79 μmol L-1 in surface water. The specific and selective recognition of chiral compounds and metal ions by our probe make it suitable for real field applications.

Facile synthesis of a 3D magnetic graphene oxide/Fe3O4/banana peel-derived cellulose composite aerogel for the efficient removal of tetracycline.

Many initiatives have incorporated graphene oxide (GO) and biomass into aerogels for wastewater treatment. We report on the facile fabrication of a magnetic GO/Fe3O4/banana peel-derived cellulose (bio-cellulose) aerogel using an ultrasound-assisted mechanical mixing method and freeze-drying technique for the removal of tetracycline (TC). The component materials and composite aerogel were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), nitrogen adsorption-desorption analysis, and vibrating sample magnetometry (VSM). The effects of solution pH and adsorbent dose on the adsorption performance of the synthesized adsorbents were investigated. The adsorption behavior at the equilibrium of the GO/Fe3O4/bio-cellulose aerogel was studied and analyzed using four well-known non-linear models: Langmuir, Freundlich, Sips, and Temkin. The results showed that the experimental data fitted well with the Freundlich and Sips isotherm models. The maximum adsorption capacity achieved from the Sips model was 238.7 mg g-1. The adsorption kinetics were studied and proved to follow the Elovich kinetic model with an initial rate of 0.89 g g-1 min-1. These results confirm the favorable adsorption of TC on the heterogeneous surface that exhibits a wide range distribution of adsorption energies of the desired GO/Fe3O4/bio-cellulose aerogel. The experimental findings demonstrate that the aerogel possesses the notable features of environmental friendliness, cost-effectiveness, and comparatively high TC adsorption capacity. Therefore, utilizing biomass to develop the structure of the magnetic GO-based composite aerogel is significantly promising for antibiotic-containing wastewater treatments.

Accelerated synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives using dendritic mesoporous nanosilica functionalized by hexamethylenetetramine: a novel nanocatalyst.

Xanthene and acridine derivatives are interesting organic compounds that are used in different research fields like biomedicine and pharmaceutical science. However, applied catalysts for their synthesis have some limitations such as long reaction times, the need for harsh conditions and low yield. So, discovery of novel catalysts for the synthesis of xanthene and acridine derivatives is highly demanded. To overcome the limitation of previous methods on the efficient synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives, a green heterogeneous organic nano-catalyst (Cu@KCC-1-nPr-HMTA) was synthesized by covalent attachment of hexamethylenetetramine to the cavities and channels of dendritic mesoporous nanosilica (KCC-1). The prepared nano-catalyst was identified using various spectroscopic and microscopic methods including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray energy diffraction (EDX), EDX mapping and nitrogen adsorption-desorption analysis (BET-BJH). The prepared green nano-catalyst showed a spherical and dendritic structure with a surface area of 65.699 m2 g-1, average pore size of 40.78 nm and pore volume of 0.66 cm3 g-1. Also, Cu@KCC-1-nPr-HMTA has many chemo-active sites for the condensation reaction and was used as an efficient nano-catalyst towards one-step synthesis of 1,8-dioxo-decahydroacridine and 1,8-dioxo-octahydroxanthene derivatives from the reaction of aromatic aldehydes, dimedone, and ammonium acetate under solvent-free conditions. Short reaction times of 1 to 5 minutes for 1,8-dioxo-decahydroacridine and 30 to 55 minutes for 1,8-dioxo-octahydroxanthene derivatives, high yields and mild reaction conditions are advantages of the proposed synthetic method. It is hoped that the engineered nano-catalyst will be used for the synthesis of other organic compounds in the future.