Adsorptive removal of ciprofloxacin from simulated wastewater using crosslinked starch ester: Isotherms, kinetics, thermodynamics, modeling, and simulation for continuous operation

Abstract

The rise in fluoroquinolone concentrations in wastewater caused significant concern due to their potential acute toxicity to living organisms. A novel eco-friendly adsorbent, crosslinked potato starch ester, was used to remove ciprofloxacin from a simulated aqueous solution by a batch adsorption process and used its obtained parameters to solve mathematical modeling. With a maximum adsorption capacity of 243.90 mg/g, the ciprofloxacin adsorption on crosslinked potato starch ester was suitable for the Langmuir isotherm model. The kinetics of ciprofloxacin adsorption showed that the pseudo-first-order kinetic model was a good fit for the adsorption process. Thermodynamic parameters exhibited that ciprofloxacin adsorption onto crosslinked potato starch ester was exothermic, achievable, and spontaneous. Finally, the process is simulated under various operating conditions using the mathematical model of a fixed bed continuous adsorption column. According to the results, under optimal operation conditions of inlet fluid velocity, particle size, bed height, and initial ciprofloxacin concentration with values 0.002 m/s, 1.2 mm, 0.2 m, and 143.4 mg/L, respectively, the highest dynamic adsorption capacity was 18.75 mg/g.