Polypyrrole- and polyaniline-supported TiO₂ for removal of pollutants from water

In recent decades, the modification of titanium dioxide (TiO₂) as a well-known photocatalyst with different strategies, such as morphological change, doping and supported substrate, has been investigated. The main goals of the modification process can be described as (a) enhancing titanium dioxide performance and (b) providing a situation that uses titanium dioxide under visible or sunlight radiation. Different types of materials have been used for titanium dioxide support, among them polymers; in particular, polypyrrole (PPy) and polyaniline (Pan), that seem to be very effective due to considerable chemical and environmental stability in the aqueous phase. Meanwhile, by combining PPy and Pan with titanium dioxide, the energy of the band gap of supported titanium dioxide may be reduced and the photocatalytic process can be carried out under visible light illumination. This review demonstrates different strategies (their mechanisms and drawbacks) for enhancing titanium dioxide performance. In the field of PPy- and Pan-supported titanium dioxide, photocatalysts present a comprehensive study on their synthesis and application for removal of dye and organic pollutants. The effects of various parameters on the photocatalytic performance of PPy/titanium dioxide and Pan/titanium dioxide are also demonstrated. The main mechanisms of organic contaminants’ photodegradation by PPy/titanium dioxide and Pan/titanium dioxide in water (via an aqueous solution) are also investigated.