Easy-handling semi-floating TiO₂-based aerogel for solar photocatalytic water depollution

One of the capital issues of photocatalytic technology is how to use photocatalytic materials in real world conditions. Suspension photocatalysts are the most effective, while the handling and recovery of nanoparticles are very challenging and costly. Herein, we report the design of semi-floating aerogel TiO_2-based photocatalyst for the oxidation of dyes and photoreduction of Cr(VI). TiO₂ aerogel-based photocatalyst was fabricated through in situ polymerization using borax, poly(vinyl alcohol) and polyvinylidene in the presence of H₂O₂ as a catalyst. Cubic TiO₂ aerogel of few centimetres was designed for the photocatalytic tests under solar light irradiation. TiO₂ aerogel showed a good photoactivity against the oxidation of three types of dyes and Cr(VI) photoreduction. In terms of dyes, the kinetics of methylene blue oxidation was the fastest as compared to rhodamine B and methyl red, while, a total reduction of Cr(VI) at 10 ppm was obtained within 30 min after the addition of tartaric acid as hole scavenger. TiO₂ aerogel can be easily recovered, washed and recycled. TiO₂ aerogel can move freely from the top to the deep solution. The semi-floating property could be an advantage to enhance the mass transfer along with bulk solution, as compared to totally floating-based photocatalysts.