Adsorption removal of pefloxacin from water by halloysite nanotubes

• We have carried out the batch adsorption experiments for pefloxacin using HNTs.
• The isotherm data fit well with the Freundlich model.
• The kinetic data fit well with pseudo-second order and intra-particle diffusion model.
• ΔG < 0 and ΔH > 0 indicated the spontaneous and endothermic nature of the adsorption.

Batch adsorption experiments were carried out for the removal of pefloxacin from water using halloysite nanotubes as adsorbent. The effects of various parameters such as contact time, initial solution concentration and temperature on the adsorption system were investigated. The optimum contact time was found to be 100 min. The isotherm adsorption data fit well with Freundlich model, and the kinetic data fit well with the pseudo-second order and the intra-particle diffusion model. Intra-particle diffusion analysis demonstrates that pefloxacin diffuses quickly among the particles at the beginning of the adsorption process, and then the diffusion slows down and stabilizes. Thermodynamic parameters such as ΔG, ΔH and ΔS were also calculated. The negative Gibbs free energy change and the positive enthalpy change indicated the spontaneous and endothermic nature of the adsorption, and the positive entropy change indicated that the adsorption process was aided by increased randomness.

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