Simple hydrothermal synthesis of magnetic MnFe_2O_4-sludge biochar composites for removal of aqueous Pb~(2+)

摘要

The magnetic MnFe2O4-sludge biochar composites (MFSB) was synthesized in one-step hydrothermal approach, realizing hydrothermal carbonization of sludge and preparation of MnFe2O4 simultaneously. The characterizations of prepared adsorbents indicated that the combination of hydrothermal sludge biochar and MnFe2O4 enhanced the structure of the hydrothermal sludge, prevented the agglomeration of MnFe2O4, and endowed the composites with magnetism and higher specific surface area. Batch adsorption experiments showed higher adsorption efficiency of MnFe2O4-sludge biochar composites with sludge content of 1.5 g (MFSB-1.5) to Pb2+. In the Pb2+ adsorption process on MFSB-1.5, the better fit of Pseudo-second-order model and the Langmuir isotherm was demonstrated, with a maximum adsorption amount of 174.216 mg/g at the reaction temperature of 25 celcius. Based on adsorption mechanism analysis, the Pb2+ adsorption onto MFSB-1.5 mainly resulted from physical adsorption, electrostatic attraction, co-precipitation, and complexation. Due to simple operation, strong adsorption capacity, effortless magnetic separation, and sludge resource utilization, MFSB-1.5 composites have great potential in removing Pb2+ from the water body.