Sorption of hydrophobic organic contaminants on functionalized biochar: Protagonist role of π-π electron-donor-acceptor interactions and hydrogen bonds

Mohammad Boshir Ahmed; John L Zhou; Huu H Ngo; Md Abu Hasan Johir; Liying Sun; Mohammad Asadullah; Dalel Belhaj

doi:10.1016/j.jhazmat.2018.08.005

Sorption of hydrophobic organic contaminants on functionalized biochar: Protagonist role of π-π electron-donor-acceptor interactions and hydrogen bonds

J Hazard Mater. 2018 Oct 15:360:270-278. doi: 10.1016/j.jhazmat.2018.08.005. Epub 2018 Aug 7.

Authors

Mohammad Boshir Ahmed¹, John L Zhou², Huu H Ngo¹, Md Abu Hasan Johir¹, Liying Sun³, Mohammad Asadullah⁴, Dalel Belhaj⁵

Affiliations

¹ School of Civil and Environmental Engineering, University of Technology Sydney, 15 Broadway, NSW, 2007, Australia.
² School of Civil and Environmental Engineering, University of Technology Sydney, 15 Broadway, NSW, 2007, Australia. Electronic address: junliang.zhou@uts.edu.au.
³ Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
⁴ Eurofins Lancaster Laboratories-Environmental, LLC, 2425 New Holland Pike, Lancaster, PA, 17601, USA.
⁵ University of Sfax-Tunisia, FSS, Department of Life Sciences, Laboratory of Biodiversity and Aquatic Ecosystems Ecology and Planktonology, Street of Soukra Km 3.5, BP 1171, CP 3000, Sfax, Tunisia.

PMID: 30125743
DOI: 10.1016/j.jhazmat.2018.08.005

Abstract

The sorption of five potent endocrine disruptors as representative hydrophobic organic contaminants (HOCs) namely estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2) and bisphenol A (BPA) on functionalized biochar (fBC) was systematically examined, with a particular focus on the importance of π-electron-donor (phenanthrene: PHEN) and π-electron-acceptors (1,3-dinitrobenzene: DNB, p-amino benzoic acid: PABA) on sorption. Experimental results suggested that hydrogen-bond formation and π-π-electron-donor-acceptor (EDA) interactions were the dominant sorption mechanisms. The sorption of HOCs decreased as E1 > E2 > EE2 > E3 > BPA based on the Freundlich and Polanyi-Mane-models. The comparison of adsorption coefficient (K_d) normalized against hexadecane-water partition coefficient (K_HW) between HOCs and PHEN indicated strong π-π-EDA interactions. π-π interactions among DNB, PHEN and HOCs were verified by the observed upfield frequency (Hz) shifts using proton nuclear magnetic resonance (¹H NMR) which identified the specific direction of π-π interactions. UV-vis spectra showed charge-transfer bands for π-donors (PHEN and HOCs) with the model π-acceptor (DNB) also demonstrating the role of π-π EDA interactions. The role of π-electron-donor and π-electron-acceptor domains in fBC was identified at different solution pH.

Keywords: EDCs; HOCs; Hydrogen bonds; fBC; π-π-EDA interaction.