Titanium dioxide nanotube arrays with silane coupling agent modification for heavy metal reduction and persistent organic pollutant degradation

Abstract

Among the technologies for removal of deposited heavy metals and degradation of persistent organic pollutants, TiO₂ semiconductor catalysts have gained extensive attention owing to their excellent catalytic ability, relatively stable physical and chemical properties and competitive price. But there are still some drawbacks associated with these TiO₂ semiconductor catalyst materials such as their weak adsorption and photocatalytic abilities in managing the organic pollutants and difficulties in recycling the TiO₂ powder (P25). Therefore, a new class of TiO₂ nanotube (TiO₂-NT) arrays was synthesized using the silane coupling agent KH570 as a modifier and applied in the reduction of heavy metals, and degradation of phenol and persistent organic pollutants like Poly Brominated Diphenyl Ethers (PBDEs). The products were thoroughly characterized by SEM, TEM, DTG, AFM, BET, EDS, DRS and XRD, which confirmed that the surface of TiO₂ was well modified by KH570. From the degradation experiment of phenol and BDE47, along with the heavy metal reduction experiment we can see that the catalytic efficiency (2 h) of the modified catalyst was 5%, 15% and 3–20% higher than that of the unmodified catalyst, respectively. As a kind of hole scavenger on the surface of catalysts, the modified TiO₂ nanotube arrays could not only enhance the adsorption effect of catalysts on organic pollutants, but also increase the electronic separation efficiency of holes. The results also indicated that this new class of catalyst had advantages both in surface modification and materials recycling, providing a new direction in environment pollution control.