This paper presents the fabrication, characterization, and testing of the photocatalytic potential of a non modified titania nanotube (TNT) and Sn-modified TNT synthesized through a facile one-step hydrothermal method. Two tin compounds (SnCl2 and SnO2) and aqueous solutions (HCl and SnCl2) were utilized as precursors and acid washing solutions, respectively. Because the Sn-modified TNT was free of calcination, the resulting sample possessed a high Brunauer-Emmett-Teller surface area. In addition, the Sn-modified TNT exhibited higher electron-hole separation efficiency. The photocatalytic reaction rate for the sample with methylene blue and malachite green dye decomposition was governed on the basis of their pre-adsorption abilities. The Sn-modified TNT had more Cl species than the non-modified TNT, resulting in higher pre-adsorption abilities for the methylene blue dye. Even though the Cl species on SnO2-TNT sample surface were removed, a higher electron hole separation efficiency and anatase-rutile mixed phase can promote the photocatalyst activity of SnO2-TNT. On the other hand, the Cl species on the surface of SnO2-TNT-HCl washing sample appeared to act as one of the adsorption sites and enhance gaseous elemental mercury removal.