Low-cost carbon-based sorbents for the removal of pharmaceuticals from wastewaters

Abstract

The increasing occurrence of pharmaceuticals in wastewater poses environmental and health risks. This study focuses on developing and evaluating cost-effective carbon sorbents, specifically biochar and graphitic carbon nitride, for efficiently removing pharmaceutical contaminants from 2023 wastewater samples from a treatment plant serving around 300,000 people. The adsorptive capabilities of these materials were evaluated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of pharmaceuticals and their metabolites. Characterization of these sorbents encompassed analyses of their physical and chemical attributes, such as specific surface area, porosity, and functional group composition, thereby aiding in elucidating their adsorption mechanisms. The study revealed a direct correlation between sorption efficacy and specific surface area. The most effective sorbent was identified as a biochar blend, comprising both commercially available corn and wood-derived biochar and laboratory-synthesized biochar from conifer cones. Notably, this sorbent demonstrated exceptional efficiency in reducing concentrations of major pharmaceutical pollutants. The levels of clarithromycin were reduced from 320 ng/L to 30 ng/L, trimethoprim from 160 ng/L to 8.6 ng/L, telmisartan from 1600 ng/L to 66 ng/L, and diclofenac from 880 ng/L to 260 ng/L.