title: Highly efficient liquid-phase photooxidation of an azo dye methyl orange over novel nanostructured porous titanate-based fiber of self-supported radially aligned H2Ti8O17 x 1.5H2O nanorods.
abstract: Novel nanostructured porous fibers of self-supported, radially aligned H2Ti8O17 x 1.5H2O nanorods were prepared from layered H2Ti4O9 x 1.2H2O tetratitanate fibers by novel solvothermal reaction in glycerine at 150-250 degrees C. The H2Ti8O17 x 1.5H2O fibers with diameters of 0.5-1.5 microm and lengths of 10-20 microm consist of multi-scale nanopores and nanostructures. They also are of high crystallinity, large surface area of 127 m2 g(-1), and stable phase up to 350 degrees C. Photocatalytic activity of the H2Ti8O17 x 1.5H2O fibers was evaluated in aqueous photooxidation of an azo dye methyl orange in the presence of UV irradiation and 02, using P-25 as the standard sample. Both the photocatalytic activity and the dispersity-agglomeration property of H2Ti8O17 x 1.5H2O fibers are pH-controllable. Highly photooxidative activity, superior to that of P-25, occurs at pH 6.0-11.0 due to certain distinguishable material characteristics and to large amounts of adsorbed reactants of surface active OH* free radicals, surface hydroxyl OH, O2*-, O*OH, and methyl orange. The agglomeration of H2Ti8O17 x 1.5H2O fibers becomes more serious from pH 2.0 to pH 5.0 and from pH 6.0 to pH 11.0. Well-dispersed H2Ti8O17 x 1.5H2O fibers occur at pH 6.0. Both the total photodegradation of waste chemicals and the entire sedimentation of H2Ti8O17 x 1.5H2O fibers can be timed to end simultaneously at suitable pH value. The photocatalyst-free reaction solution is then easily removed, and the fresh wastewater is added again. Standard unit operation processes of chemical engineering are used to design a continuous, low-cost, large-scale, liquid-phase photocatalysis technique based on the H2Ti8O17 x 1.5H2O fibers.
authors.affiliation: College of Chemical Engineering and College of Material Science and Engineering, Nanjing University of Technology, Nanjing, 210009, Peoples' Republic of China. nzh_bao@yahoo.com
authors.forename: Ningzhong
authors.initials: N
authors.lastname: Bao
authors.forename: Xin
authors.initials: X
authors.lastname: Feng
authors.forename: Zhuhong
authors.initials: Z
authors.lastname: Yang
authors.forename: Liming
authors.initials: L
authors.lastname: Shen
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Lu
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry*; D036103:Nanotechnology; D010084:Oxidation-Reduction; D010777:Photochemistry; D016062:Porosity; D014025:Titanium / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D007202:Indicators and Reagents; C009495:titanium dioxide; C100258:methyl orange; D014025:Titanium