Use of mine waste for H2O2-assisted heterogeneous Fenton-like degradation of tetracycline by natural pyrite nanoparticles: Catalyst characterization, degradation mechanism, operational parameters and cytotoxicity assessment

Abstract

Degradation of tetracycline (TTC) with a heterogeneous Fenton-like pyrite/H 2 O 2 process by pyrite from mine waste as a mineral catalyst was investigated. The study focused on identifying the main oxidizing agents and degradation mechanisms along with operational variables including solution pH, pyrite and H 2 O 2 concentration, contact time, solution temperature, and initial TTC concentration. Catalyst characterization tests revealed that pyrite is a mesoporous powder with a high degree of FeS 2 purity. Radical scavenger tests demonstrated that • OH was the main oxidizing agent generated by both solution and surface phase reactions. During the pyrite/H 2 O 2 process, more than 85% of TTC was mineralized in 60 min and the maximum TTC removal was attained in the solution at an acidic pH value (4.1). The most abundant transformation products of TTC, formed by the attack of • OH radicals, were simple chain carboxylic acids. Cultured cells of human embryonic kidney (HEK) were used for the cytotoxicity assessment of raw and pyrite/H 2 O 2 treated TTC solutions. The results illustrated that the viability of HEK cells was enhanced considerably after treating TTC solutions under optimal conditions. Accordingly, pyrite originating from mine waste is a practically effective and cost-effective catalyst in heterogeneous Fenton-like systems for mineralization and degradation of emerging contaminants such as antibiotics. • Nano-sized pyrite with highly purity prepared from mine waste was used as a mineral catalyst. • Hydroxyl radicals are the main oxidants for TTC degradation in the pyrite/H 2 O 2 process. • Both solution and surface sulfur-defects are responsible for. • OH generation • The pyrite/H 2 O 2 process acquired comprehensive removal of 50 mg/L TTC and over 85% mineralization during 60 min. • The pyrite/H 2 O 2 process is an effective AOP for removing emerging contaminants.