Hydrogen Peroxide-Modified Biochars from Wetland Plants for Bisphenol A Removal in Water

In this study, hydrogen peroxide-modified biochars from wetland plants were synthesized and employed for aqueous bisphenol A (BPA) removal, which achieved equilibrium within 300 min. The adsorption trend increased with increasing initial BPA concentration or contact time before reaching adsorption equilibrium. The pseudo-second-order adsorption kinetic model and Langmuir adsorption isotherm model fitted well with the adsorption data. The maximum adsorption capacities of Phragmites australis and Typha orientalis biochar carbonized at 500 °C for 6 h and modified with 5% hydrogen peroxide reached 10.589 and 8.483 mg/g, respectively. The modification of hydrogen peroxide resulted in the highest specific surface area of 7.143 m2/g for P. australis and 9.848 m2/g for T. orientalis, thereby promoting the adsorption of BPA. Characterization showed that hydrogen peroxide increased micropore and mesopore volumes and micropore and mesopore surface areas of biochars, disrupted the microcrystalline structures, and reduced the regularity of biochars. The regeneration study demonstrated that the hydrogen peroxide-modified biochars exhibited reusability for up to five cycles, with a reduction in the BPA removal efficiency of 10.67% for P. australis biochar and 10.07% for T. orientalis biochar.