Photocatalytic degradation of ammonia by light expanded day aggregate (LECA)-coating of TiO_2 nanopartides

摘要

Photocatalytic degradation of ammonia on supported TiO_2 nanoparticles was investigated. The TiO_2 nano-particles used as photocatalyst were coated on light expanded clay aggregate granules (LECA), which is a porous and light weight support. Photocatalytic reaction activity of prepared catalyst was determined by ammonia degradation from water synthetically polluted with ammonia. Experiment results showed significantly high photocatalytic activity for the immobilized catalysts. The ammonia was removed more than 85% within 300 min of the process with optimum calcinations temperature 550 ℃ and pH 11. Kinetics of the photocatalytic reaction followed a pseudo-first order model. XRF, XRD and SEM analyses revealed a rather uniform coating of TiO_2 on the support. By using floated TiO_2/LECA as a photocatalyst in aqueous solution of NH_3, the ammonia was photodegraded into N_2 and H_2 gases, while NO_2 and NO_3~- were formed at very low concentrations.