Removal of ciprofloxacin as an emerging pollutant: A novel application for bauxite residue reuse

Abstract

Ciprofloxacin, a widely used fluoroquinolone antibiotic frequently detected in aquatic environments, represents a group of emerging pollutants with the potential to spread antibiotics resistance. Bauxite residue, an industrial waste produced in vast quantities, was evaluated for its potential in the removal of ciprofloxacin as a sustainable sorbent material for the first time. The removal of ciprofloxacin by bauxite residue was positively correlated to the cation exchange capacity and specific surface area of bauxite residue, suggesting that cation exchange was the primary mechanism contributing to ciprofloxacin removal. Kinetics analysis indicated that ciprofloxacin removal by bauxite residue could be adequately modeled with first-order kinetics. Further testing revealed that the application of bauxite residue in the removal of ciprofloxacin was most effective under the conditions of circumneutral pH, low ionic strength, low concentrations of ciprofloxacin, and ambient temperatures lower than 40 °C. These process conditions would be typical of natural surface waters, suggesting the potential utility of bauxite residue in these environments. Bauxite residue has been shown to be effective in the removal of diverse groups of pollutants including nutrients, heavy metals, and various organics. Findings from this study further expanded the spectrum of pollutants for the application of bauxite residue and provided insight needed for the development of treatment processes using bauxite residue as a sustainable source of sorbent material.