Application of H-titanate nanofibers for degradation of Congo Red in an annular slurry photoreactor

Anatase nanofibers (TiO2–N) were synthesized as photocatalyst for the application in an annular slurry photoreactor (ASP). The unique properties of TiO2–N have facilitated its high reactivity and suitability for water treatment. The influence of operational variables: TiO2–N loading, pH, aeration rate and dye concentration on the photo-degradation kinetics and efficiency to remove a model compound of Congo Red (CR) were investigated. The photo-degradation kinetics of CR followed the Langmuir–Hinshelwood regime at lower pH. The Langmuir adsorption constant, KL–H was determined as 7.695 × 102 dm3 mol−1. The optimal photo-degradation rate of 3.47 × 10−2 mol dm−3 min−1 was achieved at 60 ppm CR, pH 3, aeration rate of 5 dm3 min−1 and TiO2–N loading of 4 g dm−3. Batch settling tests based on Kynch's theory revealed that the TiO2–N photocatalysts could produce a settling velocity of 8.38 × 10−4 ms−1. It was expected that these novel TiO2–N particles can deliver a true engineering solution as an industrial process for photocatalytic water treatment.