Adsorption of Tricyclazole and 2,4-Dichlorophenoxyacetic Acid onto Biochar Produced from Anaerobically Digested Sludge

Anaerobically digested sludge-derived biochar was produced through pyrolysis at 700 °C, called BC700. BC700 was characterized using a scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FTIR), and the Brunauer–Emmett–Teller (BET) method. The factors influencing the adsorption process and the mechanism involved in adsorbing tricyclazole and 2,4-D in single and binary systems were revealed. The theoretical maximum adsorption capacities of BC700 for tricyclazole and 2,4-D in a single system were 11.86 mg/g and 7.89 mg/g, respectively. In the binary system, the theoretical saturated adsorptive capacities of tricyclazole and 2,4-D were 5.27 mg/g and 3.20 mg/g, respectively. The adsorption of tricyclazole and 2,4-D by BC700, whether in single or binary systems, matched closely with the Freundlich isotherm and the pseudo-second-order model. This study indicates that anaerobically digested sludge-derived biochar is potentially valuable for removing pesticide contamination in surface water.