Surface functionalization of natural hydroxyapatite by polymerization of β-cyclodextrin: application as electrode material for the electrochemical detection of Pb(II).

Rodrigue Tchoffo,Emmanuel Ngameni,Guy B P Ngassa,Giscard Doungmo,Arnaud T Kamdem,Ignas K Tonlé

doi:10.1007/s11356-021-15578-8

Abstract

A composite material prepared by polymerization of β-cyclodextrin (β-CD) on the surface of natural hydroxyapatite using citric acid as cross linker, was employed as electrode material for the detection of Pb(II). Hydroxyapatite was obtained from bovine bones, following a three-step procedure including pre-calcination, chemical treatment with (NH4)2HPO4, and calcination. The structure and morphology of the pristine hydroxyapatite (NHAPP0.5) and its functionalized counterpart (NHAPp0.5-CA-β-CD) were examined using XRD, FTIR, and SEM. Upon deposition as thin film on a glassy carbon electrode (GCE), the ion exchange ability of NHAPp0.5-CA-β-CD was exploited to elaborate a sensitive sensor for the detection of lead. The electroanalytical procedure was based on the chemical accumulation of Pb(II) ions under open-circuit conditions, followed by the detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The reproducibility of the proposed method, based on a series of 8 measurements in a solution containing 2 μM Pb(II) gave a coefficient of variation of 1.27%. Significant parameters that can affect the stripping response of Pb(II) were optimized, leading to a linear calibration curve for lead in the concentration range of 2 × 10-8 mol L-1 - 20 × 10-8 mol L-1 (R2 = 0.998). The detection limit (3S/m) and the sensitivity of the proposed sensor were 5.06 × 10-10 mol L-1 and 100.80 μA.μM-1, respectively. The interfering effect of several ions expected to affect the determination of lead was evaluated, and the proposed sensor was successfully applied in the determination of Pb(II) ions in spring water, well water, river water and tap water samples.

Highlights

Due to their non-biodegradability and especially their toxicity, inorganic pollutants such as heavy metals pose a major threat to the environment because of their involvement in many natural and industrial processes (Adebisi et al 2017)
Furthermorer, comparing the spectra of pristine HAP and NHAPP0.5-CA-β-CD samples clearly showed additional peaks at 2933 and 1729 cm− 1 that are respectively attributed to the vibrations bands of C-H groups of β-CD and C = O bands of ester bonds formed during the polymerization (Leprêtre et al 2009; Tang et al 2013; Tcheumi et al 2019; Heydari and Sheibani 2015)
The observed absorption bands of ester groups indicated that hydroxyl groups of β-СD have reacted with the carboxyl groups of citric acid, leading to the formation of a threedimensional polymer network (Tcheumi et al 2019)

Summary

Introduction

Due to their non-biodegradability and especially their toxicity, inorganic pollutants such as heavy metals pose a major threat to the environment because of their involvement in many natural and industrial processes (Adebisi et al 2017). Several studies have reported the use of this material as electrode modifier for the detection of various organic pollutants (El Mhammedi et al 2007; El Mhammedi et al 2009a; Li et al 2009; Yin et al 2010; Tchoffo et al 2021).

Results

Conclusion