engleski

Isotherm, kinetic and thermodynamic study of ciprofloxacin sorption on sediments

In this study equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The Kd parameter from Linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin– Radushkevich (D–R) sorption models were applied to describe the equilibrium isotherms by linear and non-linear method. The estimated Kd values varied from 171 to 37347 mL/g. The obtained values of E (free energy estimated from D-R isotherm model) were found to be from 3.51 to 8.64 kJ/mol for all experiments indicated that ciprofloxacin sorption on sediment is a physical nature which is in agreement with obtained H°. According to obtained n values as measure of intensity of sorption estimate from Freundlich isotherm model (from 0.69 to 1.442), ciprofloxacin sorption on sediments can be categorized from poor to moderately difficult sorption characteristics. Kinetics data were best fitted by the pseudo-second-order model (R2 > 0.999). Thermodynamic parameters including the Gibbs free energy (G°), enthalpy (H°) and entropy (S°) were calculated to estimate the nature of ciprofloxacin sorption. Results suggested that sorption on sediments was a spontaneous and exothermic process.

ciprofloxacin ; sediment ; sorption ; isotherm ; ionic strength ; temperature ; kinetic and thermodynamic study

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