Sorption-photocatalysis of structurally distinct pesticides using polythiophene/TiO2 composites: Kinetics, equilibrium, reusability and operational economics

Abstract

An integrated process involving adsorption and photocatalysis are utilized for the breakdown of three different pesticides such as 2,4-D, 4-CPA and TCP. Photo-catalysts were fabricated using polythiophene supported TiO2 composites and utilized for the pesticides degradation under UV light irradiation. The synthesized materials were characterized for elemental, microscopic, spectroscopic and spectrophotometric properties. The outcome shows that polythiophene supported titanium dioxide systems can successfully facilitate the breakdown of pesticides under UV irradiation. The photocatalytic effectiveness of the TiO2 catalyst was significantly improved by the addition of polythiophene. Maximum amount of adsorption capacity for 2,4-D, 4-CPA and TCP were 8.18, 6.333, and 9.681 mg/g by pTh-1. The modified version of the Langmuir-Hinshelwood (L-H) model explained the inter-relationship between the adsorption and photodegradation. Results explained that the pTh-1 catalyzed photodegradation of 4-CPA, TCP and 2,4-D exists the surface reaction which was rate-limiting. Langmuir- Hinshelwood and electrical energy per order (EEO) model provided good fit with batch-mode experiments. Furthermore, these models were successful in elucidating the mechanisms of photocatalytic degradation when pTh-1 was available in the reaction mixture.