Photodegradation of the Herbicide 2,4-Dichlorophenoxyacetic Acid in the Presence of TiO2 and P25/βCD Nano Photocatalysts in the Photoreactor

The dichlorophenoxyacetic acid (2,4-D) is common and toxic herbicide used around the world to control wide leaf weeds present in cereal crops. This herbicide is resistant to biodegradation and chemical degradation in the environment. The main purpose of this study is synthesis and optimizing of titania nanoparticles and evaluating their effectiveness in photodegradation of 2,4-D from aqueous solutions in both batch and flow photoreactors including light emitting diod (LED).

The First, the P25/βCD nano photocatalst was synthesized and then its efficiency in the 2,4-D photo degradation was compared with commercial P25 nanophotocatalyst in both of the batch and flow photoreactors. Effective parameters include; the effects of nanocatalyst dose, select the best bed of catalyst, the β-CD amount on bed catalyst, irradiation time, kind of photoreactor on the photocatalytic degradation efficiency were investigated. The degradation was monitored using a UV-Vis spectrophotometer in 2,4-D absorption band at 284 nm.

The optimum amount of P25, P25/β-CD nano photocatalysts were 1 and 0.1 g/L, respectively. In batch photoreactor the photodegradation efficiency of 2,4-D after 5 h with P25 and P25/β-CD as a photocatalyst were approximately 81 and 85% respectively. Also, in flow photoreactor 2,4-D degradation yeild after 5 h in presence of P25 and P25/β-CD nano photocatalysts were 88.8 and 90.4% respectively. Also, after 5 consecutive periods of irradiation, photodegradation efficiency in presence of P25 and P25/β-CD nano photocatalysts were maintained 82.6 and 84%, respectively which indicates their remarkable stability.

The using of photodegradation process for the removal of organic pollutants, such as herbicides from aqueous solutions, is successful.