Dual-Enhanced Photocatalytic Activity of Fe-Deposited Titanate Nanotubes Used for Simultaneous Removal of As(III) and As(V)

Abstract

Fe-deposited titanate nanotubes (Fe-TNTs) with high photocatalytic activity and adsorptive performance were synthesized through a one-step hydrothermal method.Initial As(III) oxidation followed by As(V) adsorption by Fe-TNTs could simultaneously remove these two toxic pollutants from aqueous solutions. The apparent rate constant value for photo-oxidation of As(III) under UV irradiation by Fe-TNTs was almost 250 times that by unmoidified TNTs. Under visible light, the Fe-TNTs also exhibited enhanced photocatalytic activity after Fe was deposited. Fe 3+ located in the interlayers of TNTs acted as temporary electron-or hole-trapping sites, and attached α-Fe 2 O 3 played the role of a charge carrier for electrons transferred from TNTs. These two effects inhibited electron-hole pair recombination thus promoting photocatalysis. Moreover, the As(V) adsorptive performance of Fe-TNTs also improved, owing to the presence of additional adsorption sites, α-Fe 2 O 3 , as well as increased pH PZC . Furthermore, Fe-TNTs exhibited good photocatalytic and adsorptive performace even after 5 reuse cycles. The present tests, concerning an initial As(III) photocatalysis and subsequent As(V) adsorption process, highlight the feasibility and importance of Fe used to modify TNTs. This study proposes a feasible method to simultaneously remove As(III) and As(V) from contaminated water using a novel Ti-based nanomaterial.

The Use of Ultra-Small Fe3O4 Magnetic Nanoparticles for Hydrothermal Synthesis of Fe3+-Doped Titanate Nanotubes

“…In particular, the diffraction peak near which represents the interlayer distance of TNT is shifted from for S1 to 8.79° for S2, i.e., the interlayer distance in the modified TNT decreased. This result is opposite to the observation of the increase in the distance between the interlayer layers of Fe-TNT prepared by the method published in paper [ 37 ]. However, in the paper [ 37 ] no hydrochloric acid solution was used during the washing procedure, which is crucial for the degradation of iron oxide nanoparticles, which become a source of embedded iron ions.…”

“…The methods of doping titanate nanotubes with ions depend on the specific application. The examples of ions that are often used are Fe 3+ [ 34 , 35 , 36 , 37 , 38 ], Co 2+ [ 39 , 40 , 41 ], Ni 2+ [ 39 ], Mn 2+ [ 42 ], Gd 3+ [ 43 ], Yb 3+ [ 44 ], Nd 3+ [ 44 ], Au 3+ [ 45 ], Pt 2+ [ 45 ]. They show how diverse the methods of doping TiO 2 nanotubes are.…”

Synthesis, Characterization and Enhanced Photocatalytic Activity of Iron Oxide/Carbon Nanotube/Ag-doped TiO2 Nanocomposites

“…This transforms into reactive oxygen species, such as The iron oxide present in the catalyst can act as a temporary site for capture of electrons (e , there is a strong tendency for charge transfer of the TiO 2 surface to the iron oxide, forming the hydroxyl and superoxide radicals (equations 6 and 7). 55,62,68 (6) (7) The hydroxyl radicals and the superoxide anion produced in this process have sufficient oxidative potential to degrade phenol molecules (equations 8 and 9).…”

Simultaneous removal of Cr(VI) and 4-chlorophenol through photocatalysis by a novel anatase/titanate nanosheet composite: Synergetic promotion effect and autosynchronous doping

“…However, pure titanate possesses two main defects: (1) low adsorption capacity for metal anions (like Cr(VI) and As(V)) and organics [27][28][29], and (2) weak photocatalytic activity because of the immediate recombination of photo-generated electron-hole pairs [18,[30][31][32]. Therefore, combination of TiO2 and titanate would appear to be a sensible method for simultaneous removal of both heavy metals and organics through initial photocatalysis and subsequent adsorption.…”