污泥基生物炭处理酸性含U(Ⅵ)废水的效能与机理

通过城市污泥（SS）慢速热解制备污泥基生物炭（SSB），并研究初始pH、投加量、共存离子、吸附时间和温度等因素对SSB去除U(Ⅵ)的影响，探讨吸附动力学和吸附等温线特征。通过元素分析、扫描电镜（SEM）、傅里叶红外光谱（FTIR）、X射线衍射（XRD）和X射线光电子能谱（XPS）分析U(Ⅵ)吸附去除的机理。结果表明SSB去除U(Ⅵ)的适宜条件为：pH=3、投加量1 g/L、吸附时间240 min；在此条件下，在温度30℃时最大吸附量为34.51 mg/g。吸附动力学符合拟二级动力学模型；Langmuir吸附等温模型能更好描述生物炭对U(Ⅵ)的吸附行为。U(Ⅵ)吸附去除机理主要包括静电作用，与Si—O—Si的n-π相互作用，与羟基（—OH）、羧基（—COOH）的配位络合。通过5次吸附-解吸试验发现，U(Ⅵ)去除率和SSB再生率均在80%以上。本研究表明污泥基生物炭具备处理与修复酸性含U(Ⅵ)废水污染的潜力。

The efficiency and mechanism of U(Ⅵ) removal from acidic wastewater by sewage sludge-derived biochar

Sewage sludge-derived biochar (SSB) was prepared by slow pyrolysis of sewage sludge (SS), and the effect factors, including initial pH, dosage, coexisting ions, contact time and temperature, on the U(Ⅵ) adsorption by SSB were investigated. The adsorption kinetics and isotherm were also studied. The mechanism of U(Ⅵ) adsorption removal was analyzed by elemental analysis, scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the suitable conditions for U(Ⅵ) removal were pH of 3, dosage of 1 g/L and adsorption time of 240 min under 30°C. Under these conditions, a maximum adsorption capacity of 34.51 mg/g was obtained. The adsorption kinetics of U(Ⅵ) was accurately described by a pseudo-second-order model. Langmuir adsorption isotherm model can describe the adsorption behavior of U(Ⅵ) well. The adsorption mechanisms mainly include electrostatic interaction, n-π interaction of Si—O—Si, coordination complexation of hydroxyl (—OH) and carboxyl (—COOH) groups. Based on 5 adsorption-desorption cycles, the efficiencies of both U(Ⅵ) removal and SSB regeneration were above 80%. This study indicated that sewage sludge-derived biochar has the potential for acidic U(Ⅵ)-containing wastewater treatment.