Transport of Bisphenol A, Bisphenol S and three Bisphenol F isomers in saturated soils

Abstract

Abstract With the limitation of the use of bisphenol A (BPA), the production of its substitutes, bisphenol S (BPS) and bisphenol F (4,4’-BPF) is increasing. Understanding the fate and transport of BPA and its substitutes in porous media can help reduce their risk of contaminating soil and groundwater systems. In this study, column and batch adsorption experiments were performed with 14C-labeled bisphenol analogs and combined with mathematical models to investigate the interaction of BPA, BPS, 4,4’-BPF, 2,2’-BPF and 2,4’-BPF with four standard soils with different soil organic matter (SOM) contents. The results show that the transport capacity of BPS and 4,4’-BPF in the saturated soils is significantly stronger than that of BPA. Meanwhile, the mobility of the three isomers of bisphenol F (2,2’-BPF, 2,4’-BPF and 4,4’-BPF) showed some variability in saturated soils with high SOM content. The two-site kinetic retention mode was applied to simulate and interpret experimental data, and model simulations described the interactions between the bisphenol analogs and soil very well. The fitting results show that SOM provides more adsorption sites for bisphenol analogs and these adsorption sites may be irreversible adsorption sites. For the different mobility of bisphenol analogs, hydrophobicity is the main factor leading to the difference in adsorption affinity between BPA, BPS, 4,4’-BPF and soil. The main factor leading to the difference of adsorption affinity between 4,4’-BPF and its isomers (2,2’-BPF and 2,4’-BPF) and soil may be hydrogen bonding force. In addition, the results of this study show that the relatively high mobility of BPA substitutes BPS and 4,4’-BPF may pose a significant risk to groundwater quality, so 4,4’-BPF and BPS may not be environmentally friendly alternatives to BPA. In addition, as by-products of 4,4’-BPF production, 2,2’-BPF and 2,4’-BPF have high mobility in soil and may pose a more significant threat to groundwater than 4,4’-BPF.