Sumpun Wongnawa

Rubber sheet strewn with TiO2 particles: Photocatalytic activity and recyclability

A new method for the preparation of rubber sheet strewn with titanium dioxide particles (TiO2-strewn sheet) is presented. This simple and low cost method is based on the use of TiO2 powder (Degussa P25) being strewn onto the sheet made from rubber latex (60% HA) through a steel sieve. The characteristic of the TiO2-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) and X-ray diffractometer (XRD) techniques. The photocatalytic activity of TiO2-strewn rubber sheet was evaluated using Indigo Carmine (IC) dye as a model for organic dye pollutant in water. The results showed that the TiO2-strewn sheet could degrade IC dye solution under UV light irradiation. The effects of pH, initial concentration, and the intensity of UV light on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used TiO2-strewn sheet can be recovered and reused. The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO2-strewn sheet.

Studies on complex formation between curcumin and Hg(II) ion by spectrophotometric method: a new approach to overcome peak overlap.

Complex formation between curcumin and Hg(II) ion MeOH/H2O (1: 1 v/v) was investigated and monitored by the spectrophotometric method. The absorption peak of unreacted curcumin which was close and overlapped with that of the complex, was removed by calculation using Microsoft Excel, thereby, allowing determination of the stoichiometry of the complex by the mole-ratio and the Job’s continuous variation methods. Both methods indicated that a 1:1 complex of curcumin and Hg(II) was formed in solution. The formation constant of the 1:1 Hg(II) complex was obtained from two methods, the equilibrium concentration calculation and the linear plot of Benesi-Hildebrand equation, as log K = 4.44 ± 0.16 and 4.83 ± 0.02, respectively. The structure is proposed as a tetrahedral complex of Hg(II) with one curcumin and two chloride ions as ligands.

Copper(II) complex as a precursor for formation of cyano-bridged pentanuclear FeIII-CuII bimetallic assembly: Synthesis, characterization, crystal structure and antibacterial activity

Abstract[CuL(ClO4)2] (1) (L = 3,10-diisobutyl-1,3,5,8,10,12-hexaazacyclotetradecane) was synthesized by condensation reaction of ethylenediamine, formaldehyde and iso-butylamine in absolute ethanol. Characterization of 1 utilized various spectroscopic techniques, viz. elemental analysis, electrospray ionization-mass spectrometry (ESI-MS), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), diffuse reflectance spectroscopy (DRS) and thermogravimetric analysis (TGA). Based on these techniques, the structure of 1 was proposed as Cu(II) ion occupying octahedral geometry with four secondary amine nitrogens of the hexaazamacrocyclic ligand and two perchlorato anions. 1 was used as a precursor in the preparation of cyano-bridged bimetallic compound, [CuL]3[Fe(CN)6]2⋅5H2O (2), by reaction with K3[Fe(CN)6] in aqueous solution. Single-crystal X-ray analysis indicated that 2 crystallized in the monoclinic system with space group P21/n. The structure of 2 consisted of cyano-bridged FeIII-Cu II pentanuclear molecules having two [Fe(CN)6] 3− anions connected to three cis-[CuL] 2+ cations via two cis-cyanide ligands from each ferrate unit. In each of pentanuclear unit, the central [CuL] 2+ cation exhibited a distorted octahedral geometry while the other two units exhibited a distorted square pyramidal geometry. The room temperature magnetic moments of both complexes were measured to be 1.92 B.M. for 1 and 5.61 B.M. for 2. The in vitro antibacterial activity of 1 against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853 strains were studied and compared with standard drugs, which showed moderate antibacterial activity compared with Penicillin and Gentamicin. Graphical AbstractA copper mononuclear complex was synthesized, characterized with various techniques, and used as a precursor to synthesize a pentanuclear (FeIII-CuII) complex. The Xray structure of the new pentanuclear complex is reported. The precursor copper complex exhibited moderate antibacterial activity.

Determination of impurities in ilmenite ore and residues after leaching with HCl-ethylene glycol by energy dispersive X-ray fluorescence (EDXRF) spectrometry

Abstract Samples of ilmenite ore, 3 g each, were leached with 125 ml of a mixture of concentrated HCl-ethylene glycol at the boiling point of the leaching solution. The leaching times were in the range 70–130 h. The residues after leaching were analyzed by Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry. Only Fe and Mn were substantially leached out from the ore while other elements (Y, Zr, Nb, Sn and W) remained unleached.

Triton X-100 induced cuboid-like BiVO 4 microsphere with high photocatalytic performance

A highly active visible light-induced BiVO4 photocatalyst was prepared by a simple co-precipitation method using ammonia solution as a pH adjustor and Triton X-100 (TX100) as a structure directing agent. The physical properties of the prepared BiVO4 photocatalyst were investigated by several techniques such as X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area measurement, scanning electron microscopy (SEM), energy dispersive analysis (EDS), Fourier-transformed infrared spectroscopy (FT-IR), photoluminescence (PL), and UV-Vis diffused reflectance spectroscopy (DRS). XRD results revealed the existence of a monoclinic scheelite structure in both the unmodified and the modified samples. The TX100 played a crucial role to control the cuboid-like shape morphology of BiVO4. The DRS results showed that the as-prepared cuboid BiVO4 possessed enhanced visible light absorption range compared with that of the unmodified BiVO4. The photocatalytic activity was evaluated via indigo carmine (IC) degradation under visible light irradiation. The modified BiVO4 showed higher photocatalytic efficiency than the unmodified BiVO4 and the commercial P25-TiO2 which could be ascribed to the better charge separation efficiency.

X-Ray Crystal Structure of a Novel 2D Mn(II) Coordination Polymer with 4,4′-trimethylenedipyridine and 3-nitrophthalate as Ligands

Abstract[Mn2(μ-4,4′-trimethylenedipyridine)(μ-3-nitrophthalate)2(H2O)4]n is synthesized using MnCl2·4H2O, 4,4′-trimethylenedipyridine, and 3-nitrophthalic acid as starting materials. The complex is investigated by Fourier transform infrared spectroscopy, single crystal X-ray diffraction, elemental analysis, powder X-ray diffraction, diffused reflectance spectroscopy, photoluminescent spectroscop, and thermogravimetric analysis. The complex crystallizes in the orthorhombic system in the space group Aba2 with cell parameters a = 30.1451(10) Å, b = 9.8718(3) Å, c = 11.3258(4) Å, V = 3370.40(19) Å3, and Z = 4. The complex exhibits a 2D structure with each Mn(II) atom octahedrally coordinated to three oxygen atoms from two 3-nitrophthalate units, two oxygen atoms from two water molecules, and one nitrogen atom from 4,4′- trimethylenedipyridine.

Enhanced Photocatalytic Activity by Silver-Modified Bismuth Vanadate

Silver-modified bismuth vanadate (Ag-BiVO4) photocatalysts were easily prepared via the co-precipitation method. The effects of silver contents on the chemical properties of BiVO4 were evaluated. The prepared Ag-BiVO4 samples were characterized by several techniques such as X-ray diffractometry (XRD), scanning electron microscopy (SEM), and diffused reflectance UV-Vis spectroscopy (DRS). The mixed phase of monoclinic scheetlite structure and characteristic peaks of silver particles were found. Silver contents strongly affect the morphology of the prepared Ag-BiVO4 samples. DRS spectra revealed that the synthesized Ag-BiVO4 samples exhibited strong absorption in the visible region. The absorption in the visible zone is responsible for the high photocatalytic activity of Ag-BiVO4 under visible light irradiation. The photocatalytic degradation of methylene blue under visible light irradiation was studied using the BiVO4 as photocatalysts. The photocatalytic results reveal that the prepared Ag-BiVO4 samples could degrade the methylene blue dye.

Crystal structure of bis­[μ-1,2-bis­(di­phenyl­phosphan­yl)ethane-κ2P:P′]bis[(N,N′-di­ethyl­thio­urea-κS)iodidocopper(I)]

The binuclear title complex, [Cu2I2(C26H24P2)2(C5H12N2S)2], lies about an inversion centre. The CuI atom displays a distorted tetrahedral coordination geometry defined by one S atom of an N,N′-diethylthiourea ligand, two P atoms derived from two bridging 1,2-bis(diphenylphosphanyl)ethane (dppe) ligands and one iodide ion. The dppe ligand bridges two symmetry-related CuI ions, forming a 10-membered Cu2P4C4 ring. An intramolecular N—H⋯I hydrogen bond is noted. In the crystal, N—H⋯I hydrogen bonds link complex molecules into layers parallel to (-101).

Di­aqua­bis­(cinnamato-κ2O,O′)cadmium

The title complex, [Cd(C9H7O2)2(H2O)2], was obtained as an unintended product of the reaction of cadmium nitrate with hexamethylenetetramine and cinnamic acid. The CdII ion lies on a twofold rotation axis and is coordinated in a slightly distorted trigonal–prismatic environment. In the crystal, the V-shaped molecules are arranged in an interlocking fashion along [010] and O—H⋯O hydrogen bonds link the molecules, forming a two-dimensional network parallel to (001).

Alexdrandrite Effects and Pseudosymmetry in Aluminum Oxalates

Three chromium doped potassium aluminum oxalates, (K3[Al0.95Cr0.05(C2O4)3]·3H2O) “Blue”, (K2/3Na7/3[Al0.95Cr0.05(C2O4)3]·4H2O) “RedCubic”, and (K18{Na[Al0.964Cr0.036(C2O4)3]6}Cl·18H2O) “Red-Hexagonal” were prepared from aqueous solutions of K3[Cr(C2O4)3]·3H2O, K3[Al(C2O4)3]·3H2O and NaCl, and their solid state and solution properties were rationalized from their crystal structures, analysis data and solid state and solution UV-vis spectra. Crystals of “RedCubic” are characterized by a metrically cubic I-centered unit cell, but do have actual tetragonal symmetry derived by ordering of sodium and potassium ions not compatible with the apparent cubic symmetry. Results of 13C-NMR, EPMA/EDX, SC-XRD, and UV-Vis spectroscopies are discussed in relation to the compound’s structures and color behavior. In aqueous solution RedCubic and Blue show the same greenish purple color and identical electronic absorption peaks. In the solid state, they have different colors and show slightly different absorption peaks. Their color behavior as well as the Alexandrite color-change effect observed in the two Red crystals are rationalized based on the compounds’ absorption peaks.