Iron-modified peat and magnetite-pine bark biosorbents for levofloxacin and trimethoprim removal from synthetic water and various pharmaceuticals from real wastewater

Abstract

Humans are at significant risk of antibiotic resistance genes (ARGs) and antimicrobial resistance (AMR) via exposure to pharmaceutical contaminants in water, so there is a strong need for cost-effective environmental solutions to mitigate this crisis. This study introduces iron-modified peat and magnetite-pine bark as efficient, low-cost and green biosorbents for the adsorption of pharmaceutical contaminants from wastewater. Peat biomass, modified by iron extracted from a groundwater treatment sludge was dissolved in acid to prepare the iron-modified peat biosorbent, and pine (Pinus sylvestris) bark as a forest industry by-product was mixed with iron salts (Fe3+: Fe2+ = 2:1) to obtain the magnetite biosorbent. The adsorption of levofloxacin was little influenced by pH compared to trimethoprim. The equilibrium removal efficiency of antibiotics over both biosorbents was reached after 180 min contact time. The maximum adsorption capacity over iron-modified peat was about 200 mg/g for both antibiotics and over magnetite-pine bark 153.0 mg/g for levofloxacin and 184.1 mg/L for trimethoprim. Possible antibiotic adsorption mechanisms were proposed based on the Fourier transform infrared spectroscopy (FTIR) analysis. Experiments with real wastewater effluent revealed trimethoprim removal of 56.6–84.3% (dosage: 3 g/L). Moreover, a variety of other pharmaceuticals were removed by the biosorbents.