Adsorption behavior of bisphenol A on sediments in Xiangjiang River, Central-south China

The overall objective of this study was to investigate adsorption behavior of bisphenol A (BPA) on sediments through batch adsorption experiments. The sediment samples were collected from Xiangjiang River (Changsha, Central-south China). Data obtained from adsorption experiments show that the rapid adsorption plays the main role rather than slow adsorption in adsorption process of BPA on sediments. Freundlich model can describe the adsorption behavior of BPA on sediments very well. The calculated Kf (mg1−n ln g−1) ranged from 0.0072 to 0.0178 (n ranged from 0.6944 to 0.8106). Through analyzing the data of adsorption experiments and properties of sediments, we consider that black carbon (e.g. soot- and charcoal-like material, collectively termed black carbon or BC) and hole-filling domain of the organic matters in sediment are responsible for the observed nonlinear adsorption and desorption hysteresis. The calculated hysteresis coefficient H ranged from 0.6718 to 1.0928. Negative and low molar formation enthalpy (ΔH0 = −5.735 kJ mol−1) indicates that adsorption process of BPA on sediments is an exothermic reaction, attributed to the physical adsorption which is dominated by dispersive force and driven by enthalpy thoroughly. In this study, the amount of adsorbed BPA on sediment was found to decrease as sediment concentration increased, whereas it increased with an increase of ironic concentration. In acidic surroundings, the amount of adsorbed BPA on the sediment was found to decrease as pH value increased, whereas it varied indistinctively in alkaline surroundings.