Development of a new PET flow reactor applied to food dyes removal with advanced oxidative processes

Abstract

Scientists have been exploring new sustainable alternatives in effluent treatment due to the growing concern with highly stable organic pollutants. In this work, a photocatalytic flow reactor was developed from Poli Ethylene Terephthalate (PET) bottles in order to optimise photocatalysis of two synthetic dyes commonly found in food industry wastewater. Four different photo-oxidative systems were tested within 360 min under UV-C radiation. The best results were obtained in a UV-C/H2O2/TiO2 system due to the synergic effect of the oxidizing agents. The influence of the oxidizing agent’s amounts was investigated in a 2² experimental planning and 99.25% of dyes degradation could be reached in 180 min. A kinetic study was carried out with these results and the kinetic rate for the global reaction was estimated at 0.016 min−1 and half-life reaction time at 43.32 min applying the pseudo-first-order kinetic model. Acute toxicity assays revealed the IC50 increased 165.8% after the treatment indicating the by-products were less toxic than the parental compounds. TOC and COD were evaluated as water quality parameters and decreased from 40.50 and 103.4 mg L−1 to 8.25 and 15.0 mg L−1 after the photocatalytic process, respectively. Cost analysis of the construction and operation expenses and removal efficiency presented the developed PET flow reactor as a feasible alternative to the treatment of synthetic organic dyes.