This paper reports an effective method to reduce nanofibers' diameter of functionalized TiO2/Nylon 6-6 nanofibers, by dissolving polymer layers through formic acid solutions, to improve incorporated nano particles' adsorption efficiency. In order to investigate the effects of floatation in 2, 3 and 4 M formic acid solutions for different periods (A.R.F) on the nanofibers' diameter and nanoparticles' exposure, Cu2+ adsorption was applied. Due to floatation nanofibers in the formic acid solutions, the diameter decreased and incorporated TiO2 nanoparticles were exposed on the outer surface of fibers. The results revealed that best treatment performance was about 77%. Furthermore, by using A.R.F process and the decrease in polymer concentrations improved on Cu2+ removal from 77% to 92.1%, as a result of which nanoparticles' exposure was further improved. (C) 2017 Elsevier Ltd. All rights reserved.