Biowaste valorization on pharmaceuticals and pesticides abatement in aqueous environments

Abstract

This study focuses on the abatement of pharmaceuticals and pesticides in water using sustainable biosorbents. Adsorption kinetics and equilibrium measurements were performed to characterize the adsorption of fluoxetine hydrochloride (FLX), carbamazepine (CRB) and atrazine (ATZ) by raw pine bark. The amount of adsorbed pollutants by mass of adsorbent followed the order: FLX (0.652 mg/g) > ATZ (0.522 mg/g) > CRB (0.144 mg/g), explained by the different interactions between the untreated pine surface and the target pollutants, according to the adsorption mechanism proposed. The evaluation of chemically and thermically modified pine was also assessed. In terms of the overall entrapment capability, pine bark modified with HNO3 was shown to be the best biosorbent (1.95 mg/g). The economic feasibility of the biosorbents was evaluated through a detailed cost analysis. Among the performed modifications, the one with H2O2 was the most expensive procedure, 23.7 /mmol (pollutants mixture) being the hydrochar production the less expensive, 1.1 /mmol. Through desorption assays it was found that 100% of FLX, 98% of CRB and 30% of ATZ, respectively, can be recovered from raw pine, using 50% (v/v) acetonitrile solution. The recyclability of the natural biosorbent was evaluated by adsorption-desorption cycles. Pine bark can be regenerated and reused at least for two times, without losing its adsorption efficiency. A pre-pilot air-lift type reactor was investigated as an effective rehabilitation approach to treat contaminated water, for up-scale purpose. Using biowastes for emerging pollutants entrapment can be considered a sustainable water rehabilitation pathway, promoting a circular bioeconomy and environmental protection.