污泥活性炭的表征及其对Cr（Ⅵ）的吸附特性

以城市污水处理厂污泥为原料，采用磷酸活化一微波热解法制备得到污泥活性炭，并将其用于吸附水溶液中的Cr（Ⅵ）。分别采用元素分析仪（VarioELcube）、比表面积孔径分布测定仪（ASAP2020）、扫描电镜（SEM）和傅里叶红外光谱（FT—IR）等仪器对原污泥及污泥活性炭的表面组成和结构进行表征，探讨污泥活性炭的孔隙结构参数和表面化学性能。通过静态吸附实验，考察了溶液初始pH，接触时间，初始Cr（Ⅵ）浓度对污泥活性炭吸附Cr（Ⅵ）效果的影响，并探讨了污泥活性炭去除Cr（Ⅵ）的机理。实验结果表明，pH越低吸附效果越好，吸附平衡时间为100h。不同温度下吸附过程均符合Langmuir等温吸附模型，30℃时最大吸附容量为27．55mg／g；吸附动力学过程符合准二级速率方程（R2〉0．99）；污泥活性炭对Cr（Ⅵ）的去除是一个吸附-还原耦合的过程。

Characterization of sludge-based activated carbon and its adsorption properties on Cr（Ⅵ）

Sewage sludge was used as precursor to develop a sludge-based activated carbon （SAC）by the method of H3 PO4 activation-microwave pyrolysis. The resulting materials were evaluated as adsorbents for the re- moval of Cr（Ⅵ） from aqueous solution. The elemental analyzer,specific surface porosity detector,scanning elec- tron microscope and Fourier transform infrared spectrometry were used to evaluate the pore structural parameters and surface chemistry properties of sewage sludge and sludge-based adsorbents, respectively. The effects of vari- ous parameters,such as pH,contact time and Cr（Ⅵ） initial concentration were investigated in astatic adsorption experiment. The results showed that the adsorption equilibrium time of Cr（Ⅵ） onto sludge-based activated car- bon was 100 h, and low pH value was beneficial for the adsorption. The experimental adsorption isotherm data were well fitted with Langmuir model and the maximum adsorption capacity of Cr（Ⅵ） was found to be 27.55 mg/g at 30℃ ,in the solution of pH 3.0 ± 0.05. The kinetic study demonstrated that the adsorption process was followed the pseudo second-order kinetic equation. The removal of Cr（Ⅵ） by Sludge-based activated carbon was found to be a adsorption-coupled reduction process based on batch experiments.