Kinetics, Equilibrium, and Thermodynamics of the Sorption of Bisphenol A onto N-CNTs-β-Cyclodextrin and Fe/N-CNTs-β-Cyclodextrin Nanocomposites

Keletso Mphahlele,Sabelo D Mhlanga,Maurice S Onyango

doi:10.1155/2015/214327

Abstract

We analysed the adsorptive behaviour of Fe/N-CNTs-β-CD nanocomposite in the removal of bisphenol A (BPA) from aqueous solution and identified the key influencing parameters. The Fe/N-CNTs-β-CD nanocomposite adsorbent was prepared by dispersing Fe uniformly on N-CNTs-β-CD using a microwave polyol method and characterized using Fourier transform infrared spectroscopy (FTIR), focused ion beam scanning electron microscopy (FIB-SEM), and energy-dispersive X-ray spectroscopy (EDS). The solution pH and temperature had minimal effect on sorption of BPA while the initial concentration and adsorbent mass affected the adsorption of BPA. No leaching of Fe into the water was observed; thus the nanocomposites were found suitable for use in water purification. From equilibrium isotherm studies, the Langmuir isotherm model gave the best description of the experimental data. The Langmuir monolayer adsorption capacities of BPA onto N-CNTs-β-CD and Fe/N-CNTs-β-CD are 38.20 mg·g−1and 80.65 mg·g−1at 298 K, respectively. Evidently, these adsorption capacity values gave an indication that uniform dispersion of Fe N-CNTs-β-CD prepared by the microwave polyol method enhances the adsorption of BPA. Meanwhile, the sorption kinetics of BPA onto Fe/N-CNTs-β-CD were best described by the pseudo-second-order model.

Highlights

Bisphenol A (BPA) is generally used as a monomer in the fabrication of polycarbonates and epoxy resins, as an antioxidant in polyvinyl chloride (PVC) plastics, and as an inhibitor of end polymerization in PVC polymers [1]
The sorbent was characterized before and after BPA sorption and the results are as discussed in Sections 3.1.1 and 3.1.2
It is well known that CDs form host-guest complexes with hydrophobic compounds [18]. These results suggested that BPA was trapped by the sorbents through the hydrophobic interaction and the hydrogen-bonding interaction simultaneously [39]

Summary

Introduction

Bisphenol A (BPA) is generally used as a monomer in the fabrication of polycarbonates and epoxy resins, as an antioxidant in polyvinyl chloride (PVC) plastics, and as an inhibitor of end polymerization in PVC polymers [1]. Due to the recurrent usage of polycarbonate plastics, epoxy resins, and PVC in industry and at homes, BPA has been allegedly observed in rivers, seas, and soils. BPA is difficult to remove once it builds up in the environment or in the human body due to its poor solubility (381 mg⋅L−1 in water) [4]. The main sources of BPA discharged to environmental water are expected to be the release of industrial wastewater and municipal effluent [5]. The removal of BPA from environmental water is necessary and critical

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Conclusion