Highly water-dispersible and easily recyclable anatase nanoparticles for photocatalysis

摘要

A simple, scalable sol-gel method was developed for preparing anatase TiO2 nanoparticles under mild conditions without the use of surfactants. The synthesized nanocrystals can be easily dispersed in acidic (pH < 4) or alkaline (pH > 8) aqueous solutions, and form a transparent hydrocolloid which remains stable for more than 1 year. However, the TiO2 nanoparticles could be precipitated from the stable hydrocolloid by adjusting the pH to 5-7, and the nanoparticles harvested by simple filtration. The synergistic effect of the steric hindrance of an ethoxy group on the nanoparticle surface and Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory force were used to explain the ease with which the nanoparticles redisperse in water, the high stability of the suspensions, and the reversible and controllable water dispersibility of TiO2 nanocrystals. Finally, the anatase nanoparticles were used as a recyclable photocatalyst to degrade Rhodamine B (Rh B) under 175 W High-Pressure Mercury Lamp illumination. Freshly prepared TiO2 nanoparticles exhibited a high photodegradation efficiency of 99% and the nanocatalyst retained its 99% efficiency even after 10 degradation cycles. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.