Adsorption and photocatalytic detoxification of diazinon using iron and nanotitania modified activated carbons

Abstract Diazinon is used as an insecticide for different types of cultivation. It is considered to be a toxic pollutant. In this work, we present a comparative study of diazinon detoxification by two methods: adsorption and photocatalytic degradation. Chemically activated carbon (AC) was prepared from flamboyant pods. AC was modified with iron (Fe-AC) to be used as a solid adsorbent for diazinon. TiO 2 and TiO 2 -AC, as photocatalysts for degradation of diazinon, were prepared by the sol–gel method. Textural and surface characterizations of the prepared solid samples were carried out using nitrogen adsorption at −196 °C, scanning electron microscopy (SEM), pH PZC and the Boehme titration method. Adsorption of diazinon was investigated on AC and Fe-AC considering the effects of pH, time, adsorbent dosage and concentration. The results showed that the adsorption capacity of Fe-AC is three times higher than that of AC. Furthermore, as the adsorbent dosage increases, the diazinon removal percentage increases, and adsorption follows pseudo-first- and pseudo-second-order equations. The diazinon photocatalytic degradation efficiency for TiO 2 -AC is higher than that for TiO 2 ; the diazinon degradation percentage reaches 95% in the case of TiO 2 -AC and only 55% in case of TiO 2 after 80 min.