Enhanced photoelectrocatalytic performance of TiO2 nanotube array modified with WO3 applied to the degradation of the endocrine disruptor propyl paraben

Abstract

A B S T R A C TWe report on the photoelectrocatalytic degradation of the endocrine disruptor propyl paraben (PPB) using a TiO 2 nanotube (TiO 2 -NT) electrode prepared via chemical anodization, and a TiO 2 -NT electrode modified with WO 3 by electrodeposition. Solutions containing 50 mg L − 1 PPB were subjected to the photoelectrocatalytic process in a 0.2 L one-compartment electrochemical cell under UV/VIS irradiation, and the effects of bias potential (+ 0.5, + 1.0 and +1.5 V) and solution pH (3.0, 7.0 and 10) on the performances of the unmodified and modified electrodes were investigated. Scanning electron micrographs (SEM) showed that the nanotubes were highly organized and perpendicularly aligned with a mean length of 800 nm. According to energy dispersive X-ray and SEM analyses, the concentration of W in the TiO 2 -NT/WO 3 electrode was~0.75% and the distribution of the modifier was continuous and homogeneous on the surface, with pores uncovered and decorated with WO 3 . The photocurrent of the TiO 2 -NT/WO 3 electrode was improved by more than 20% in relation to its unmodified counterpart. The maximum degradation efficiencies were achieved at higher applied potentials and under acidic conditions for both electrodes. However, best results were obtained using the TiO 2 -NT/WO 3 electrode with an applied potential of + 1.50 V and at pH 3. Under these conditions, more than 99% of PPB was removed in 30 min and 94% mineralization was achieved in 60 min. The photoactivity of the electrode was highly stable even after exhaustive application, indicating that WO 3 deposition is an important method for improving the properties of TiO 2 -NT electrodes as applied to organic oxidation.

Paraben Compounds—Part II: An Overview of Advanced Oxidation Processes for Their Degradation

“…Martins et al [36] used photo-electrocatalysis for PP removal using TiO 2 nanotubes as a catalyst. At pH = 3, total removal was achieved in only 30 min.…”

“…AOP technologies such as ozonation [23][24][25]; catalytic ozonation [26]; photocatalytic ozonation [27,28]; Fenton's process [29,30]; photo-Fenton [31]; photocatalysis with UV radiation [7,32], visible radiation [6,33], and solar radiation [34]; photolysis using UV radiation [35]; photoelectrocatalysis [36]; photo-sonochemical degradation [37]; or sonochemical oxidation [38,39] were already used for parabens abatement.…”

Removal of Heavy Metals from Wastewaters: A Challenge from Current Treatment Methods to Nanotechnology Applications

“…For instance, titanium dioxide (TiO 2 ) on metallic titanium has been used for many photoelectrochemical oxidations processes. However, changing the TiO 2 morphology from film to hierarchical TiO 2 nanotubes (TiO 2 -NTs) improves electron percolation at the TiO 2 interface due to the enlarged surface area associated with the high structural organization, which increases the reactions at surface/electrolyte interface and reduces the recombination levels of electron/hole [ 138 , 139 ]. Because TiO 2 nanotubes have low toxicity, good stability and high efficiency, TiO 2 -NTs have been an ideal material for organic pollutants removal applications.…”

“…Since major reactions take place in the MMO anode surface, increasing the anode surface can be achieved by template synthesis. Examples include vertically aligned TiO 2 -NTs used as template for deposition of PbO 2 [ 141 ], SnO 2 [ 142 ] and WO 3 [ 138 ].…”

Tailoring the ORR selectivity for H2O2 electrogeneration by modification of Printex L6 carbon with 1,4-naphthoquinone: a theoretical, experimental and environmental application study

“…AOPs are based on the generation of highly reactive oxygen species, such as hydroxyl radicals ( OH), 1,12,13 and are known to promote non-selective oxidation of a wide range of organic molecules. Hydroxyl radicals can be generated using (i) semiconductor-ZnO, 14 WO 3 , 15 and TiO 2 ; 16 (ii) other precursors, such as ozone (O 3 ) 17 and hydrogen peroxide (H 2 O 2 ); 18,19 or (iii) electro-Fenton (EF) reactions where Fe 2+ catalyses the decomposition of electrogenerated H 2 O 2 for OH production. [20][21][22][23] In addition, AOPs can be combined with an irradiation source (ultraviolet or visible) to help enhance the efficiency of the treatment process.…”