Prompt removal of antibiotic by adsorption/electro-Fenton degradation using an iron-doped perlite as heterogeneous catalyst

Abstract In the current study, a novel-fangled sequential approach, adsorption/electro-Fenton, was developed for the elimination of micropollutants from aqueous matrixes. Therefore, the prompt removal of a pharmaceutical, sulfamethizole, by adsorption on carbonaceous materials is proposed. After that, the concentrated solution was treated by electro-Fenton using novel synthesized perlite-based catalyst. Initially, three different carbonaceous adsorbents (pellets carbonaceous nanogel doped with iron, honeycomb carbonaceous aerogel and orange biochar) were considered. The kinetics and isotherms of the pollutant adsorption were studied. The higher removal level was attained by the pellets with the adsorption process following a pseudo-2nd order model and being well defined by the Langmuir adsorption isotherm. After that, the pollutant was extracted from the pellets, concentrated in aqueous solution and treated by different advanced oxidation processes (anodic oxidation and electro-Fenton process). The results confirmed the higher efficiency of electro-Fenton treatment and its improvement was evaluated using a novel synthesized iron perlite catalyst. For this purpose, the synthesis of iron catalysts supported in perlite was performed by different methods (carbonisation, precipitation and hydrothermal). Among them, the hydrothermal synthesis produced catalysts with high catalytic activity, significant pollutant removal (>95 %), high stability and without iron leaching after several cycles of treatment. Based on these results, the development of a continuous treatment system was successfully carried out attaining high TOC removal values. Moreover, the feasibility of the treatment was also validated in complex water matrixes and toxicity assays demonstrated the viability of the proposed treatment for a global management of this pollutant.