REMOVAL OF CADMIUM AND LEAD IN WATER BY MAGNETIC CARBON PREPARED FROM ACTIVATED SLUDGE WITH HYDROTHERMAL CARBONIZATION
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摘要: 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。Abstract: 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.
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Key words:
- magnetic biochar /
- cadiumion /
- leadion /
- adsorption /
- water treatment
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