| In recent years, environmental endocrine disrupting chemicals (EEDCs), as one type of emerging contaminants, which have the ability to interfere with complex endocrine functions, often through mimicking or blocking endogenous hormones. Published evidence has raised public and scientific concerns. As a kind of typical environmental endocrine disruptors, widespread occurrence of bisphenol A (BPA) in environmental matrices, including air, water, sewage sludge, soil, house dust, and foodstuffs as well as human urine, blood, breast milk, and saliva is known. Concerns about the health risks of BPA are increasing, and restrictions/regulations have been put forward to limit its application in some consumer products. To comply with restrictions and regulations, manufacturers are gradually replacing BPA with other related compounds, including bisphenol S (BPS), as substitutes in industrial applications. However, the environmental behaviours and environmental fates of BPS remain unclear. It is essential to profoundly study on the distribution, transformation, mechanism and environmental risks of BPS due to its own toxicity and high contaminative potential.This study mainly conducted a series of batch adsorption experiments by using different carbonaceous sorbents and natural soils. The effects of the physical and chemical properties of both sorbents were investigated. The adsorption mechanism of BPS on carbonaceous sorbents and natural soils were discussed.The major findings and conclusion of the study are as follows:1. The surface accessibility of adsorbents played the important part of adsorption. Owing to the competitive effects of water clusters and steric hindrance, BPS showed higher sorption on MG and GP than that on MH and MC;2. In comparison to the adsorption of other BPS analogues, we hold that the hydrophobic effects, the π-π donor-acceptor interaction and electrostatic interactions were not the dominant mechanism of BPS on MWCNTs;3. The experimental results demonstrate that chemicals with a butterfly structure formed between the two benzene rings show consistently high sorption on MWCNTs, independent of the substituted electron donating or accepting functional groups. A chemical with two benzene rings presented in the same plane did not show this structural advantage for its sorption.Thus, the special butterfly structure benefited for BPS sorption on carbonaceous sorbents;4. The adsorption of BPS on natural soils correlated significantly with soil organic matter, as a result, the BPS sorption increased with foc (%);5. According to adsorption isotherms and speciation distribution, the proportion of positively charge of BPS was lower than PH and BPA at the same pH. As a result, the electrostatic attraction between the positively charged BPS and negtively charged natural soils were decreased. Overall, electrostatic attraction was likely contributed to the decreased adsorption of BPS on natural soils.6. The sulfonyl group in BPS is a strong electron-withdrawing group, which may affecte or inhibit BPS sorption through π-π donor-acceptor interactions on soil organic matters when the effects of soil minerals were ruled out. This feature is probably why the sorption of BPS was lower than PH and BPA.In summary, this study emphasized the importance of chemical conformation on organic contaminant sorption on engineered carbonaceous materials and natural soils. As the first experimental attempted to investigate the adsorption mechanisms of BPS, the results of this study is expected to offer useful information towards understanding and predicting the environmental fate and risks of BPS. |
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