Photocatalytic Activities of Boron Doped Titanium Dioxide Nanoparticles and its Composite with Polyaniline

Abstract

Titanium dioxide (TiO₂) was doped with a nonmetalic element, boron (B), and the boron doped TiO₂ (B-TiO₂) was combined with polyaniline (Pani) through an in-situ polymerization technique. The photocatalytic activity of the prepared samples was monitored by the degradation of methylene blue under UV light irradiation. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to reveal the effect of boron doping on the crystalline and chemical structure of the photocatalyst, respectively. The morphological and elemental compositional characteristics of the samples were evaluated using field emission scaning electron microscopy (FE-SEM) and energy dispersive x-ray analysis. The optical band gap energy of the prepared samples was obtained by UV-Visible (UV-Vis) spectroscopy. B-TiO₂ exhibited enhanced photocatalytic performance compared to the undoped photocatalyst. Furthermore, compared with TiO₂ and B-TiO₂, Pani/B-TiO₂ displayed superior photocatalytic activity. The composite achieved almost 26% methylene blue degradation within 150?minutes. Although the boron doping enhanced the crystallinity of TiO₂ slightly, it did not affect the morphology. FTIR confirmed the presence of tri-coordinated interstitial boron in the Ti–O–B bonds. The UV-Vis spectra displayed a red shift with the incorporation of the boron atoms. The incorporation of the boron atoms in the TiO₂ crystal structure are suggested to promote the separation of the photoinduced electron-hole pairs, a possible reason for the enhanced photocatalytic activity. B-TiO₂ and its composite with polyaniline could be considered as a promising photocatalyst to remove organic dyes from the wastewater.     

Trends in labor efficiency among American hospital markets

The health care sector is one of the most labor intensive sectors of the economy. As a major player in health service delivery, hospitals must closely examine their largest cost — labor expenses. This study evaluates trends in the efficiency of health care labor among urban hospital markets. More specifically, it assesses the hypothesis that technological changes and market and regulatory pressures have increased aggregate labor efficiency. Using data envelopment analysis (DEA), this study evaluates labor efficiency in 1989 and 1993 in 298 metropolitan statistical areas (MSAs) with two or more hospitals. Results of this study suggest that between 1989 and 1993, hospital markets generally demonstrated higher labor inefficiencies. The U.S. health care system could save approximately $16.6 billion in 1993 by eliminating hospitals' excessive use of health care provider labor.