Well-aligned, high aspect-ratio and open-ended TiO2 nanotube arrays secured within a Ti foil (TiO2 nanotubes cartridge) were successfully prepared through the double-sided anodization method. With approximate to 210 mu m of nanotube length, the anodic growth of TiO2 was accelerated and stabilized by the lactic acid-containing ethylene glycol electrolyte. In the absence of lactic acid, the anodization led to detachment of nanotubes from the Ti foil after 5-6 h of high voltage (80 V) anodization. Transmission electron microscope image and Raman spectrum revealed that the as-anodized TiO2 nanotube arrays without annealing treatment were partially crystalline anatase and demonstrated photocatalytic activity in the mineralization of formic acid. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 415-420, 2016