Novel composite from chitosan and a metal-organic framework for removal of tartrazine dye from aqueous solutions; adsorption isotherm, kinetic, and optimization using Box-Benkhen design.

Cosmetics, textiles, foodstuffs, and medicines frequently contain the yellow dye tartrazine. It has carcinogenic properties and can trigger allergies. In this study, a unique NH2-MIL-101(Cr)/chitosan composite (MIL/chitosan composite) was created using a hydrothermal process. The effectiveness of this composite in removing Tartrazine (TZ) from aqueous solutions was investigated. It was characterized via FT-IR, XPS, XRD, and BET analysis. The surface area of the MIL/chitosan nanoadsorbent sample was 1256.64 m2/g, where after five times recycling, it was reduced to 1068.14 m2/g. The study analyzed the impact of dye concentration, pH, temperature, and MIL/chitosan composite dosage. Experimental measurements were taken for the equilibrium isotherms of dye adsorption. The kinetic models and adsorption isotherm were used to analyze the results. The adsorption process was found to match Langmuir and pseudo-second-order kinetic models. Chemisorption was the mechanism of the adsorption process. Based on thermodynamic parameters, it was determined that the adsorption process was endothermic. The MIL/chitosan composite was recycled up to five cycles. Using the MIL/chitosan composite towards the adsorption of the tartrazine from the real sample has been checked. The interaction process between the MIL/chitosan nanoadsorbent and Tartrazine adsorbate has been investigated. The TZ electrical characteristics, reactivity, and shape were ascertained through the application of density functional theory (DFT). The placement of electrophilic and nucleophilic attack sites is in good agreement with the molecular orbitals (HOMO and LUMO) and MEP results, according to DFT. The optimization of adsorption results was accomplished using Box-Behnken design (BBD).

Phosphorus-substitution effect on the phase stabilization, electrical and spectroscopic properties of LAMOX-based electrolyte for solid oxide fuel cells.

A series of P5+ - doped La2Mo2O9 phases with different concentrations of P5+ were prepared using conventional solid-state reactions. The formation of phase-pure P5+-doped La2Mo2O9 has been monitored by powder X-ray diffraction, thermal analysis, conductivity measurements, Raman, and FT-IR absorption techniques. The structure and lattice parameters of La2Mo2-yPyO9-y/2 are obtained from Rietveld refinement. The effect of substituting P for Mo reveals that the phase transition which occurs in La2Mo2O9 around 560 °C disappears when y > 0.02, as demonstrated by thermal analysis. Pure P5+-doped phases with monoclinic structure (α-form, the space group P21) were observed for the concentration of optically active ions up to y = 0.02. When the concentration of P5+ ions is higher, a cubic structure (ß-form, the space group P213) starts to appear. However, up to the concentration of y = 0.03 of the P5+ ion a mixture of the monoclinic and cubic phases has been observed. From infrared and Raman analysis it is confirmed that different vibration modes arise from the vibration of molybdenum-oxygen bands. Mo-O bond lengths are also found to be independent of P-doping.

Crystal Chemistry, Optic and Magnetic Characterizations of a New Copper Based Material Templated by Hexahydrodiazepine.

Crystals of the new organic-inorganic material (DAP-H2)[CuBr4] (1); (DAP = hexahydrodiazepine (C5H14N2)) were successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermal analysis, UV-Vis-NIR diffuse reflectance spectroscopy, and magnetic measurements. X-ray investigation demonstrates that 1 crystallizes in the monoclinic space group C2/c. The supramolecular crystal structure of 1 is guided by several types of hydrogen bonding which connect anions and cations together into a three-dimensional network. The optical band gap was determined by diffuse reflectance spectroscopy to be 1.78 eV for a direct allowed transition, implying that it is suitable for light harvesting in solar cells. The vibrational properties of this compound were studied by infrared spectroscopy, while its thermal stability was established by simultaneous TGA-DTA from ambient temperature to 600 °C. The study of the photoresponse behavior of an optoelectronic device, based on (C5H14N2)[CuBr4], has shown a power conversion efficiency (PCE) of 0.0017%, with J sc = 0.0208 mA/cm2, V oc = 313.7 mV, and FF = 25.46. Temperature dependent magnetic susceptibility measurements in the temperature range 1.8-310 K reveal weak antiferromagnetic interactions via the two-halide superexchange pathway [2J/k B = -8.4(3) K].

Enhanced Adsorption and Evaluation of Tetracycline Removal in an Aquatic System by Modified Silica Nanotubes.

In the present study, a nanocomposite adsorbent based on mesoporous silica nanotubes (MSNTs) loaded with 3-aminopropyltriethoxysilane (3-APTES@MSNTs) was synthesized. The nanocomposite was employed as an effective adsorbent for the adsorption of tetracycline (TC) antibiotics from aqueous media. It has an 848.80 mg/g maximal TC adsorption capability. The structure and properties of 3-APTES@MSNT nanoadsorbent were detected by TEM, XRD, SEM, FTIR, and N2 adsorption-desorption isotherms. The later analysis suggested that the 3-APTES@MSNT nanoadsorbent has abundant surface functional groups, effective pore size distribution, a larger pore volume, and a relatively higher surface area. Furthermore, the influence of key adsorption parameters, including ambient temperature, ionic strength, initial TC concentration, contact time, initial pH, coexisting ions, and adsorbent dosage, had also been investigated. The 3-APTES@MSNT nanoadsorbent's ability to adsorb the TC molecules was found to be more compatible with Langmuir isothermal and pseudo-second-order kinetic models. Moreover, research on temperature profiles pointed to the process' endothermic character. In combination with the characterization findings, it was logically concluded that the 3-APTES@MSNT nanoadsorbent's primary adsorption processes involved interaction, electrostatic interaction, hydrogen bonding interaction, and the pore-fling effect. The synthesized 3-APTES@MSNT nanoadsorbent has an interestingly high recyclability of >84.6 percent up to the fifth cycle. The 3-APTES@MSNT nanoadsorbent, therefore, showed promise for TC removal and environmental cleanup.

Mechanochemical Promoted Heterocycles: A Solvent-free Route to Triazole Carbohydrates as Glycogen Phosphorylase Inhibitors.

AIMS: This study aimed to recommend a novel way for the preparation of carbohydrates containing triazole derivatives. BACKGROUND: Triazoles containing derivatives have numerous biological activities. Ball milling is a fast, modest, green process with massive potential. One of the greatest interesting applications of this technique is in the arena of heterocycles. OBJECTIVE: Solvent-free click reactions are facilitated via the activation of copper powder using a ball milling mechanochemical procedure. An optimization study of parameters affecting the reaction rate, such as reaction time, size, and milling ball number, has been conducted. Different substrates have been tested using this adopted procedure considering in all cases, in high yields and purity, the corresponding chiral optically pure five-membered glycoconjugates containing 1,2,3-triazole. METHODS: Three milling balls of 10 mm in diameter were placed in the milling jar (50 mL; stainless steel). 1 mmol of alkyne, 2 mmol of azide, and 1 mmol of Cu powder (63 mg) were added, respectively, in the presented order. Milling was assured for 25 min at 650 rpm deprived of solvent. RESULTS: The cycloaddition results and the deprotection of the cycloadducts were affected by the selection of the protective groups. Cleavage of the acetyl protecting groups provided water-soluble triazoles. The four 1,4-di-substituted 1,2,3-triazoles synthesized via deacetylation were tested against glycogen phosphorylase. The best inhibitor of rabbit muscle glycogen phosphorylase was 2-Amino-3-{2-[1-(3,4,5,6-tetrahydroxytetrahydro- pyran-2-ylmethyl)-1H-[1,2,3]triazol-4-yl]-ethylsulfanyl}-propionic acid b (Ki = 40.8 ± 3.2 µM). This novel procedure affords an eco-friendly reaction profile (catalyst-free) affording high yields and short reaction times. CONCLUSION: In this work, acetyl protective groups were used to the corresponding deprotected watersoluble triazole analogous to recognizing glycogen phosphorylase inhibitors. Triazole 6a was the most effective inhibitor of RMGP b with a Ki value of 40.8 µM.

Pickering Emulsions of Fluorinated TiO2: A New Route for Intensification of Photocatalytic Degradation of Nitrobenzene.

Fluorination of the TiO2 surface has been often reported as a tool to increase the photocatalytic efficiency due to the beneficial effects in terms of production of oxidizing radicals. Moreover, it is shown that the unique amphiphilic properties of the fluorinated TiO2 (TiO2-F) surface allow one to use this material as a stabilizer for the formulation of Pickering emulsions of poorly soluble pollutants such as nitrobenzene (NB) in water. The emulsions have been characterized in terms of size of the droplets, type of emulsion, possibility of phase inversion, contact angle measurements, and optical microscopy. The emulsified system presents micrometer-sized droplets of pollutant surrounded by the TiO2-F photocatalyst. Consequently, the system can be considered to be composed of microreactors for the degradation of the pollutant, which maximize the contact area between the photocatalyst and substrate. The enhanced photocatalytic activity of TiO2-F was confirmed in the present paper as the apparent rate constants of NB photodegradation were 16 × 10-3 and 12 × 10-3 min-1 for fluorinated and bare TiO2, respectively. At NB concentrations largely exceeding its solubility, the rate constant was 0.04 × 10-3 min-1 in the presence of both TiO2 and TiO2-F. However, unlike TiO2, TiO2-F stabilized NB/water emulsions and, under these conditions, the efficiency of NB photocatalytic degradation in the emulsified system was ca. 18 times higher than in the nonemulsified one. This result is relevant also in terms of practical applications because it opens the route to one-pot treatments of biphasic polluted streams without the need of preliminary physical separation treatments.

Photocatalytic Degradation Enhancement in Pickering Emulsions Stabilized by Solid Particles of Bare TiO2.

Pickering emulsions provide a new way to enhance the efficiency of photocatalytic degradation of water-insoluble pollutants. Indeed, the semiconductor solid particles dually act as the photocatalyst and stabilizer of the emulsion droplets whose size dramatically affects the photocatalytic reaction. The present work aims at the validation of this concept by using bare TiO2 without any surface modification. Nanostructured TiO2 has been prepared by a simple sol-gel process and characterized by X-ray diffraction, specific surface area analysis, scanning electron microscopy, and diffuse reflectance spectroscopy. The emulsions were prepared by using 1-methylnaphthalene (1-MN) as a model organic contaminant scarcely soluble in water and bare TiO2 as the photocatalyst/stabilizer. The emulsions have been characterized by electrical conductivity, optical microscopy, and light-scattering analyses. The photocatalytic degradation of 1-MN was 50 times faster in stable Pickering emulsions with respect to the case of biphasic liquid systems containing TiO2. This finding allows us to propose Pickering emulsions stabilized by TiO2 nanoparticles as an effective and novel way to intensify the photocatalytic degradation of water-insoluble organic pollutants.

TiO2-PANI/Cork composite: A new floating photocatalyst for the treatment of organic pollutants under sunlight irradiation.

A novel photocatalyst based on TiO2-PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline (PANI)-modified TiO2 on cork. The TiO2-PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (UV-vis DRS) and the Brunauer-Emmett-Teller (BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO2-PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency.