Development Of Nano-Sized Β-Cyclodextrin Polymers As An
Adsorbent For The Effective Removal
Of Phenolic Compounds From Aqueous Samples
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Date
2021-04
Authors
Suwaibatu, Mamman
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The use of cyclodextrin-based materials as adsorbents for removing different
contaminants is cutting-edge research that has caught the attention of many researchers
worldwide. In this research, magnetite methacrylic acid-functionalized β-cyclodextrin
(Fe3O4@MAA-βCD), magnetic molecularly imprinted polymer based on methacrylic
acid-functionalized β-cyclodextrin (MMIP MAA-βCD), magnetic non-molecularly
imprinted polymer based on methacrylic acid-functionalized β-cyclodextrin (MNIP
MAA-βCD, magnetic molecularly imprinted polymer based on methacrylic acid
(MMIP MAA) and magnetic non-molecularly imprinted polymer based on
methacrylic acid (MNIP MAA) were successfully synthesized for the removal of 2,4-
dichlorophenol (2,4-DNP), 2,4-dinitrophenol (2,4-DNP) and bisphenol A (BPA) from
aqueous media. The adsorbents were characterized by Fourier transform infrared
spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron
microscopy (TEM), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller
(BET), thermogravimetric analyzer (TGA) and X-ray Diffraction (XRD). 1H NMR
spectroscopy was used to characterize the MAA-βCD and BPA-MAA-βCD inclusion
complex. Several variables influencing the adsorption efficiency of the selected
phenolic compound have been analyzed in depth. Fe3O4@MAA-βCD gave the optimal
removal amount of the studied phenolic compounds studied at pH 2 for 2,4-DNP, pH
7 for 2,4-DCP, and pH 6 for BPA. While the contact time, initial concentration, the
adsorbent dose was set at 60 min, 10 mg/L, and 20 mg, respectively. The optimum removal efficiency at 60 min was 89%, 78%, and 69% for 2,4-DNP, 2,4- DCP and
BPA. Similarly, MMIP MAA-βCD for removing BPA gave an optimum adsorption
time of 60 min at pH 8, 10 mg/L analyte concentration, 20 mg adsorbent dose and 250
rpm stirring speed. At the optimized conditions, the removal efficiency of BPA was
found to be 96%. MMIP MAA-βCD showed high selectivity, affinity and fast kinetic
response for BPA adsorption compared to MMIP MAA (without βCD) and it was
selected as the best adsorbent. The Pseudo-second-order model provided the best fit
for the kinetic results in all the studied adsorbents. The Freundlich and Halsey model
best fitted the adsorption equilibrium data with R2> 0.9563, indicating MMIP MAA-
βCD and Fe3O4@MAA-βCD are heterogeneous systems. Thermodynamic
experiments have demonstrated that the adsorption system is thermodynamically
feasible, exothermic and spontaneous. The result also revealed that the primary type
of interactions involved in this analysis was hydrogen bonding, inclusion complex
formation and π–π interaction. These new materials incorporate both the benefit of
using supra magnetic host-guest interaction and the molecularly imprinted polymer’s
molecular recognition properties. The synthesized materials are green, easy to prepare,
efficient and easily used in large-scale operations without raising environmental or
health concerns. Also, these materials proved to be promising adsorbents for the
routine removal of the phenolic compounds from aqueous environmental samples.
Description
Keywords
Chemistry