Comparison of the efficiency of immobilized and suspended systems in photocatalytic degradation of the pirimicarb pesticide by TiO2 nanoparticles in aqueous solutions

In this study, the photodegradation of pirimicarb pesticide was investigated in presence of suspended and immobilized TiO2 on a glass plate. The influence of operational parameters (initial concentration of pirimicarb, pH and light intensity) on the photocatalytic activity of TiO2 and the kinetic of reaction was investigated. The results show that TiO2 as a photocatalyst has a good efficiency in the presence of UV-C light to remove pirimicarb from aqueous solution. The favorable conditions obtained for the photodegradation of pirimicarb were pH= 6, light intensity = 17 Wm−2, and [pirimicarb]0 = 40 mgL−1 in both the systems. Also, in the slurry system, the most suitable catalyst dosage was 300 mgL−1. The kinetic examination, following the pseudo first-order reaction kinetics, was made based on the Langmuir–Hinshelwood model. Also, the decreasing trend of total organic carbon (TOC) and the increasing trend of inorganic carbon (IC) over time and during the photocatalytic process, indicates the oxidation of organic pollutant over the reaction time.