Strainer-Separable TiO(2) on Halloysite Nanocomposite-Embedded Alginate Capsules with Enhanced Photocatalytic Activity for Degradation of Organic Dyes

Photocatalysis driven by natural sunlight is an attractive approach to removing pollutants from wastewater. Although TiO(2)–based photocatalysts using various support nano-materials with high catalytic activity and reusability have been developed for purifying wastewater, the centrifugal separation methods used for the nanocatalysts limit their use for treating large amounts of water. Here, we prepared a TiO(2) nano-catalyst supported on a halloysite nanotube (HNT)-encapsulated alginate capsule (TiO(2)@HNT/Alcap) to recapture the catalysts rapidly without centrifugation. The structure of TiO(2)@HNT/Alcap was characterized by X-ray diffraction, SEM, and TGA. In our system, the combination of HNTs and alginate capsules (Alcaps) improved the efficiency of adsorption of organic pollutants to TiO(2), and their milli = meter scale structure allowed ultra-fast filtering using a strainer. The TiO(2)@HNT/Alcaps showed ~1.7 times higher adsorption of rhodamine B compared to empty alginate capsules and also showed ~10 and ~6 times higher degradation rate compared to the HNT/Alcaps and TiO(2)/Alcaps, respectively.