Strategies developed on the modification of titania for visible light response with enhanced interfacial charge transfer process: An overview

The modification of titania by metal / non metal ion doping, coupling with narrow band gap sensitizer, surface flourination, metal deposition, and together with recent ventures on application of 001 facets of anatase titania for visible light response with enhanced charge carrier separation are briefly overviewed. © Versita Sp. z o.o

Influence of physicochemical-​electronic properties of transition metal ion doped polycrystalline titania on the photocatalytic degradation of Indigo Carmine and 4-​nitrophenol under UV​/solar light

To understand the role of dopant inside TiO2 matrix, anatase TiO2 was doped with transition metal ions like Mn2+, Fe3+, Ru3+ and Os3+ having unique half filled electronic configuration and their photocatalytic activity was probed in the degrdn. of Indigo Carmine (IC) and 4-​nitrophenol (NP) under UV​/solar light. For comparison, TiO2 was also doped with V5+, Ni2+ and Zn2+ metal ions having d0, d8 and d10 electronic configuration resp. Irresp. of excitation source UV​/solar light and nature of the org. pollutant, photocatalytic activities of doped photocatalysts followed the order: Mn2+-​TiO2 > Fe3+-​TiO2 > Ru3+-​TiO2 ≥ Os3+-​TiO2 > Zn2+-​TiO2 > V5+-​TiO2 > Ni2+-​TiO2 at an optimum concn. of dopant. Based on the exptl. results obtained, it is proposed that the existence of dopant with half filled electronic configuration in TiO2 matrix which is known to enhance the photocatalytic activity is not universal! Rather it is a complex function of several physicochem.-​electronic properties of doped titania. Enhanced photocatalytic activity of Mn2+ (0.06 at.​%)​-​TiO2 was attributed to the combined factors of high pos. redn. potential of Mn2+/Mn3+ pairs, synergistic effects in the mixed polymorphs of anatase and rutile, smaller crystallite size with high intimate contact between two phases and favorable surface structure of the photocatalyst. Despite the intense research devoted to transition metal ion doped TiO2, it is rather difficult to make unifying conclusion which is highlighted in this study

Supersensitive measurement of angular displacements using entangled photons

We show that the use of entangled photons having non-zero orbital angular momentum (OAM) increases the resolution and sensitivity of angular-displacement measurements performed using an interferometer. By employing a 4$\times$4 matrix formulation to study the propagation of entangled OAM modes, we analyze measurement schemes for two and four entangled photons and obtain explicit expressions for the resolution and sensitivity in these schemes. We find that the resolution of angular-displacement measurements scales as $Nl$ while the angular sensitivity increases as $1/(2Nl)$, where $N$ is the number of entangled photons and $l$ the magnitude of the orbital-angular-momentum mode index. These results are an improvement over what could be obtained with $N$ non-entangled photons carrying an orbital angular momentum of $l\hbar$ per photonComment: 6 pages, 3 figure

Photocatalytic degradation of imidachloprid under solar light using metal ion doped TiO2 nanoparticles: influence of oxidation state and electronic configuration of dopants

Anatase TiO2 was doped with metal ions like Th4+, V5+ and Mo6+ and tested for the degrdn. of imidachloprid under solar light. X-​ray diffraction results inferred that all the dopants stabilized the anatase phase irresp. of their nature, oxidn. state and ionic size. The undoped and transition metal ion doped TiO2 were completely transformed to rutile phase at 700° while rare earth Th4+ doped sample completely transformed to rutile phase at 1000°. The rare earth dopant stabilized the anatase phase by hindering the growth of crystallite size. Among the photocatalysts used, Th4+ (0.06​%)​-​TiO2 showed highest activity and its efficiency was 2.8 times higher than that of Degussa P-​25. The Th4+ ion lowered the band gap of TiO2 to 2.6 and 2.5 eV facilitating solar light absorption. Detrapping of the trapped charge carriers depends on electronic configuration and the oxidn. state of the dopants

ANTIBACTERIAL AND ANTIOXIDANT ACTIVITIES OF STEM BARK ESSENTIAL OIL CONSTITUENTS OF LITSEA GLUTINOSA C. B. ROB.

Objective: To evaluate the chemical composition, antibacterial and antioxidant properties of stem bark essential oil of Litsea glutinosa C. B. Rob.Methods: The essential oil isolated from stem bark of L. glutinosa and their chemical composition was analyzed by gas chromatography coupled with mass spectrometry detector. The in vitro antibacterial activity of the stem bark essential oil was investigated against eight human pathogenic bacterial clinical isolates using agar disc diffusion method and MIC value was determined by modified resazurin microtitre-plate assay. The antioxidant activity of essential oil was measured by 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH), 2, 2-azinobis-3-ethylbenzothiazoline-6-sulphonate radical cation (ABTS) and β-carotene bleaching assay.Results: GC-MS analysis of stem bark essential oil resulted in the identification of 37 compounds, off which 9,12-octadecadienoic acid (62.57%), hexadecanoic acid (12.68%), stigmast-5-en-3-ol (6.87%) and vitamin E (2.51%) were the main constituents representing 84.63% of the oil. The determination of in vitro antibacterial activity of stem bark essential oil resulted in significant inhibition zone (15.00±0.57 mm) and MIC value (0.15±0.15×10-2 mg/ml) against the pathogenic bacteria Vibrio cholera followed by Pseudomonas aeruginosa and Salmonella typhi. The results of DPPH radical scavenging (IC50:4.540±0.06 µg/ml), ABTS (IC50:256.02±0.06 µg/ml) and β-carotene bleaching assay (%I: 78.51±0.42 %) showed significant in vitro antioxidant property.Conclusion: L. glutinosa stem bark essential oil showed potential antibacterial activity against the Vibrio cholera. The results of this investigation supported the ethnomedical claim of essential oil as a demulcent, antidiarrheal and antioxidant drug

Full factorial design for optimization, development and validation of HPLC method to determine valsartan in nanoparticles

AbstractHigh performance liquid chromatographic method was optimized, developed and validated as per the ICH guidelines. In this study the 20mM ammonium formate and acetonitrile in the 57:43 ratio were used as mobile phase for the analysis of valsartan. Full factorial design was used to optimize the effect of variable factors. The responses were peak area, tailing factor and number of theoretical plates. The quadratic effect of flow rate and wavelength individually as well as in interaction were most significant (p<0.0001 and p<0.0086, respectively) on peak area; the quadratic effect of pH of buffer was also most significant effect (p<0.0001) on tailing factor (5%) whereas the quadratic effect of flow rate and wavelength individually was significant (p=0.0006 and p=0.0265, respectively) on the number of theoretical plates. The high-performance liquid chromatographic separation was performed at the flow rate 1.0min/mL, UV detector wavelength 250nm and pH of the buffer 3.0 as optimized parameters using design of experiments. The retention time values of valsartan were found to be 10.177min. Percent recovery in terms of accuracy for the prepared valsartan nanoparticles was found in the range of 98.57–100.27%

Photo-degradation of Di Azo Dye Bismarck Brown by Advanced photo-Fenton Process: Influence of Inorganic Anions and Evaluation of Recycling Efficiency of Iron Powder

The present research work has demonstrated the usage of zero valent metallic iron (ZVMI) in the photo-Fenton process under UV light as a promising and novel technique for the complete degradation of di azo dye Bismarck Brown (BB) in aqueous medium. The influence of various reaction parameters like concentration of oxidants/dye/iron powder and pH of the solution was investigated and optimum conditions are reported. Ammonium persulfate (APS) proved to be better oxidant in comparison with hydrogen peroxide for enhancing the degradation rate and effectively inhibited the precipitation of iron hydroxides at higher dosages of iron powder which is attributed to the acidity provided by APS which is crucial for Fenton process. The rate constant for the kinetics of degradation using various oxidation processes follows the order: Fe0/APS/UV > Fe0/H2O2/UV > Fe0/APS/dark > Fe0/UV > Fe0/H2O2/dark > Fe0/dark > H2O2/UV > APS/UV. The effects of inorganic anions that are commonly found in the industrial effluents like NaCl, KNO3, Na2SO4, Na2CO3 and NaHCO3 at different concentrations on the degradation rate were studied in detail. The degradation was followed by UV-vis and GC-MS techniques

Influence of various aromatic derivatives on the advanced photo Fenton degradation of Amaranth dye

The photo degrdn. of Amaranth (AR) dye by advanced photo Fenton process in the presence of sym. peroxides like hydrogen peroxide (H2O2) and ammonium persulfate (APS) are investigated. The influence of various reaction parameters like the effect of iron dosage, concn. of H2O2/APS, initial dye concn., effect of pH and the influence of various arom. derivs. were studied and optimum conditions are reported. The efficiency of the oxidant was strongly influenced by the nature of arom. photoproducts formed during the course of the degrdn. reaction. To study their effect on the rate of degrdn. these arom. derivs. were added in known concn. (10 ppm)​. The influence of various arom. derivs. on the degrdn. kinetics shows the following order: hydroquinones > chlorophenol > dichlorobenzene > arom. carboxylic acids > anilidine > nitrophenol. The addn. of these derivs. did not influence the degrdn. pathway although it altered the reaction rate. The percentage COD and TOC removal were detd. in presence of arom. derivs. to evaluate the complete removal of the pollutant. Based on the intermediates obtained in the UV-​vis and GC-​MS spectroscopic techniques probable degrdn. mechanism has been proposed