Effect of light on concomitant sequestration of Cu(II) and photodegradation of tetracycline by H-MOR/H-ß/H-ZSM5 zeolites.

It is important that a pollution remediation system be able to cater for a variety of pollutant species present in the water to be treated. The aim of this study was to utilise a series of commercial zeolites (H-MOR, H-ß, and H-ZSM5) for the concomitant adsorption and photodegradation of Cu2+ and tetracycline (TC) molecules. The adsorbent cum photocatalyst was characterised by SEM and FTIR. FTIR confirmed the key functional groups (Si-O-Si and Al-O-Si) in the series of zeolites, and H-ß zeolite was demonstrated to be the most effective adsorbent cum photocatalyst for both adsorption and photodegradation of Cu2+ and TC molecules. These results were further corroborated from the pseudo-first-order rate constant values. Among the investigated zeolites, H-ZSM5 displayed the least adsorption and photodegradation performance for Cu2+ and TC molecules. The photolysis reaction confirms the significant role of zeolites in the photodegradation test, as low performance was recorded in the absence of the zeolites.

Photocatalytic remediation of methylene blue using hydrothermally synthesized H-Titania and Na-Titania nanotubes.

Although nanotube is among the most effective morphology of Titania due to its unilateral pathway for photo-generated charge transfer and mechanical stability, its performance is still hampered by high recombination. In the present study, to further improve the photocatalytic degradation performance of Titania, univalent elements of H and Na were respectively ion-exchanged into the Titania nanotubes (TNTs). The photocatalyst was characterized using XRD, TEM, ICP-AES, and FTIR. The modified samples displayed enhanced photocatalytic degradation performance over Degussa TiO2 under UV-A light illumination of MB. The rate constants of NaTNT and HTNT were 16 and 13 times that of Degussa TiO2. Specifically, the Na-TNTs showed better photocatalytic degradation activity than H-TNTs with a rate constant of 0.12 min-1 while the latter showed 0.09 min-1. The optimum adsorption and photocatalytic performance of NaTNT were determined at pH 6 achieving about 99% MB removal within 10 min of irradiation. The ion exchange NaTNT displayed excellent reusability after the fifth cycle of the photocatalytic tests and superoxide radicals were experimentally determined to be the main reactive oxygen species involved in the photocatalytic degradation of MB.