Synthesis of EDTA-cysteine-β-cyclodextrin for the removal of organophosphate flame retardants (OPFR) from sediments and soil samples from the Buffalo River Estuary, Eastern Cape of South Africa

Abstract

Due to the growing water and environmental pollution worldwide, it is important to develop new effective materials for the remediation of sediments, soil and water contaminated with organic pollutants including flame retardants. In this study, a new soluble and hydrophilic polymer material containing ethylenediaminetetraacetic acid (EDTA), cysteine and beta cyclodextrin (β-CD) depicted as EDTA-Cysteine-β-Cyclodextrin was prepared for the removal of organophosphate flame retardants (OPFRs) from simulated sediment and soil samples and those collected from the Buffalo River Estuary in East London, Eastern Cape Province of South Africa. The β-CD was modified using cysteine and EDTA. The EDTA-Cysteine-β-Cyclodextrin was characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDX). The results show that a non-porous spherical and bubble shaped material was synthesized. For the adsorption study, different contaminants’ concentrations, solution pH, adsorbent dose and contact time were varied to ascertain the optimum conditions for the removal of OPFRs from soil and sediment. The removal of OPFRs was highly dependent on pH, adsorbent dose, concentration and contact time of the adsorption process. The optimum pH, contact time, OPFRs concentration and adsorbent dose were 3, 120 min, 60 mM and 5 mL, respectively with average adsorption percentage of 97.13 ± 14.04 %. The results proved that this newly developed polymer can decontaminate sediments and soil. The EDTA-Cysteine-β-Cyclodextrin gave promising possibilities for practical application for the remediation of OPFRs from sediment and soil samples through adsorption process.

Keywords

• EDTA-Cysteine-β-cyclodextrin
• Remediation
• Emerging contaminants
• Pollution