活性污泥水热碳化法制备磁性炭及对水体Cd2+及Pb2+的去除

以含有FeSO₄的活性污泥为原料，采用水热碳化法，在220℃，4 h条件下，制备得到磁性炭（Fe-SSBC），并实现污泥减量。以Cd2+和Pb2+为模型污染物，探究了Fe-SSBC的投加量、起始酸碱度对Cd2+和Pb2+吸附的影响以及吸附机理。采用元素分析（EA）、X射线能谱分析（EDS）、傅里叶红外光谱分析（FTIR）、比表面积（BET）、X射线光电子能谱分析（XPS）、磁滞回线对样品进行表征。研究结果表明:在投加量为0.2 g，pH为5的条件下，Fe-SSBC对Cd2+的吸附效果最好，在10 h后去除率接近100%；投加量为0.3 g，pH为6时，对Pb2+的吸附效果最佳，在8.5 h后Pb2+去除率接近100%。Fe-SSBC对Cd2+和Pb2+的吸附动力学拟合结果更符合准二级动力学模型，Langmuir吸附等温线模型能够更好地反映Cd2+和Pb2+在Fe-SSBC上的单分子层吸附，化学吸附为控制吸附过程，同时存在物理吸附。制备磁性炭在实现污泥减量的同时，具有有效去除水中Cd2+和Pb2+的作用。

REMOVAL OF CADMIUM AND LEAD IN WATER BY MAGNETIC CARBON PREPARED FROM ACTIVATED SLUDGE WITH HYDROTHERMAL CARBONIZATION

Magnetic biochar (Fe-SSBC) was prepared from activated sludge containing ferrous sulfate by hydrothermal carbonization at 220℃ for 4 h, achieving sludge reduction at the same time. Using Cd2+ and Pb2+ as the model pollutants, the effect of the Fe-SSBC dosage and the initial pH on the adsorption of Cd2+ and Pb2+ were studied, then the adsorption mechanism was investigated by adsorption kinetics and adsorption isotherm experiments. The samples were characterized by elemental analysis (EA), X ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), specific surface area (BET), X ray photoelectron spectroscopy (XPS) and hysteresis loop. The results showed that optimal condition for the best Cd2+ adsorption by Fe-SSBC was dosage of 0.2 g under pH=5, after 10 h, and the removal rate was close to 100%; while that for Pb2+ adsorption was dosage of 0.3 g under pH=6, after 8.5 h, and the removal rate was close to 100%. The adsorption kinetics of Cd2+ and Pb2+ by Fe-SSBC fitted the second-order kinetic model. The adsorption isotherm model of Langmuir could better fit the monolayer adsorption of Cd2+ and Pb2+ on Fe-SSBC. Chemisorption controlled the rate of adsorption process, and there was physical adsorption at the same time. In this study, sludge reduction was achieved by hydrothermal carbonization, meanwhile, a adsorbent was prepared to remove Cd2+ and Pb2+ effectively from water.