Sorptive removal of phenolic endocrine disruptors by functionalized biochar: Competitive interaction mechanism, removal efficacy and application in wastewater

Mohammad Boshir Ahmed,John L Zhou,Huu Hao Ngo,Md Abu Hasan Johir,Kireesan Sornalingam

doi:10.1016/j.cej.2017.11.041

Mohammad Boshir Ahmed, John L Zhou + Show 3 more

Open Access

https://doi.org/10.1016/j.cej.2017.11.041

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Abstract

Sorptive removal of six phenolic endocrine disrupting chemicals (EDCs) estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4-tert-butylphenol (4tBP) by functionalized biochar (fBC) through competitive interactions was investigated. EDC sorption was pH dependent with the maximum sorption at pH 3.0–3.5 due to hydrogen bonds and π-π interactions as the principal sorptive mechanism. Sorption isotherm of the EDCs was fitted to the Langmuir model. Sorption capacities and distribution coefficient values followed the order E1 > E2 ≥ EE2 > BPA > 4tBP > E3. The findings suggested that EDC sorption occurred mainly through pseudo-second order and external mass transfer diffusion processes, by forming H-bonds along with π-π electron-donor–acceptor (EDA) interactions at different pH. The complete removal of ∼500 μg L−1 of each EDC from different water decreased in the order: deionised water > membrane bioreactor (MBR) sewage effluent > synthetic wastewater. The presence of sodium lauryl sulphonate and acacia gum in synthetic wastewater significantly suppressed sorption affinity of EDCs by 38–50%, hence requiring more fBC to maintain removal efficacy.

Highlights

Endocrine disrupting chemicals (EDCs) can cause adverse effects due to exogenous endocrine disruption in the reproductive, sexual differentiation, neurological and immune systems even at low concentrations, and have attracted increasing attention [1,2]
In term of sorption mechanism, endocrine disrupting chemicals (EDCs) sorption mainly occurred through π-π EDA interactions and by forming different hydrogen bonds
The sorption capacity and distribution coefficient values decreased as E1 > E2 ≥ EE2 > bisphenol A (BPA) > 4-tert-butyl phenol (4tBP) > E3 due to the difference in the EDCs’ hydrophobicity

Summary

Introduction

Endocrine disrupting chemicals (EDCs) can cause adverse effects due to exogenous endocrine disruption in the reproductive, sexual differentiation, neurological and immune systems even at low concentrations (ng L-1 to μg L-1), and have attracted increasing attention [1,2]. The chemical structures and physicochemical properties of the EDCs are shown in Fig. 1 and Table 1, respectively Many separation processes such as coagulation, flocculation and precipitation have been used for the removal of EDCs from different water [3, 5]. The sorption of EDCs has been studied using single compound, there are reports on using membrane-based processes for mixture removal Carbonaceous materials such as CNT, graphene, activated carbon and biochar may have natural properties to sorb different organic contaminants simultaneously from water, such data, especially on EDCs, is scarce. MBR effluent and synthetic wastewaters were spiked with ~500 μg L-1of each EDC in the mixture before interaction with fBC for 44 to 64 h at pH 3.0-3.25, (maximum sorption-based on the pH study) at 25 oC.

Results and discussion

EDC sorption kinetics 11

Conclusions

E2 E3 EE2 BPA 4tBP pH