Study on amino-directed modification of oil sludge-derived carbon and its adsorption behavior of bisphenol A in water

Abstract

In order to remove bisphenol A (BPA) in wastewater, this paper reported an amino-functionalized oily sludge-derived carbon (GP-H-OSC) obtained by grafting amino groups using oily sludge as a precursor, which could quickly adsorb BPA in the wastewater. The adsorption results showed that the grafting modification method was more likely to form effective adsorption sites on the surface than the impregnation modification. FT-IR and Boehm titration results indicated that the oxidation modification strategy was beneficial in generating more carboxyl groups on the surface of the oily sludge-derived carbon, which could provide intermediate connection groups for the subsequent grafting. The SEM and BET results revealed that the polyethyleneimine (PEI) would form a dense mesoporous structure on the surface during the grafting process, which was conducive to the transport of pollutants. The adsorption process of BPA by GP-H-OSC conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum extent of BPA adsorption was 393.2 mg/g based on the Langmuir isotherm model. Based on the analysis of FT-IR and XPS, GP-H-OSC mainly trapped BPA in water through the formation of hydrogen bonds between the functional amino groups on the surface and the hydroxyl groups on BPA. Moreover, primary amines were more likely to form hydrogen bonds with hydroxyl groups on BPA than imines. The removal rate of GP-H-OSC for low concentration BPA wastewater could reach 95% within 1 h, and it still had strong adsorption performance after recycling experiments. In summary, it was feasible to graft PEI on the surface of sludge-derived carbon, and the obtained amino-functionalized carbon material could adsorb BPA quickly and efficiently, showing great potential in practical wastewater treatment.