镧改性净水污泥水热炭对水体中磷的吸附特性及底泥内源磷的固定

以净水污泥和氯化镧为原料，通过一步水热炭化同时负载镧，制备了镧改性净水污泥水热炭.采用SEM-EDS、 BET、 FTIR、 XRD和XPS对材料进行表征，考察溶液初始pH、吸附时间、吸附等温线和吸附动力学等，研究其对水体磷酸盐的吸附特性.结果表明，制备的材料相比净水污泥原泥，比表面积和孔容孔径有明显提高，磷吸附量大幅提升.吸附过程符合准二级动力学模型，Langmuir模型拟合对磷的最大吸附量达到72.69 mg·g^-1.主要吸附机制为静电引力和配体交换.镧改性净水污泥水热炭添加入底泥，可以有效控制底泥内源磷向上覆水的释放.分析底泥磷形态，水热炭的添加促使底泥中不稳定的NH₄Cl-P、 BD-P和Org-P向非常稳定的HCl-P转变，降低了底泥中潜在活性磷含量，同时也大幅降低了底泥中生物有效磷含量.说明镧改性净水污泥水热炭可以有效吸附去除水体磷酸盐，同时也可作为底泥改良材料，有效稳定底泥内源磷，控制水体磷含量.

Phosphorus Adsorption in Water and Immobilization in Sediments by Lanthanum-modified Water Treatment Sludge Hydrochar

Using water treatment sludge and lanthanum chloride as raw materials, lanthanum-modified water treatment sludge hydrothermal carbon was prepared through one-step hydrothermal carbonization and loading lanthanum. SEM-EDS, BET, FTIR, XRD, and XPS were used to characterize the materials. The initial pH of the solution, adsorption time, adsorption isotherm, and adsorption kinetics were investigated to study the adsorption characteristics of phosphorus in water. The results showed that the specific surface area, the pore volume, and the pore size of the prepared materials were significantly increased, and the phosphorus adsorption capacity was greatly improved compared with that of the water treatment sludge. The adsorption process conformed to the pseudo-second-order kinetic model, and the Langmuir model fitted the maximum phosphorus adsorption capacity to 72.69 mg·g^-1. The main adsorption mechanisms were electrostatic attraction and ligand exchange. Adding lanthanum-modified water treatment sludge hydrochar into the sediment could effectively control the release of endogenous phosphorus from the sediment to the overlying water. According to the analysis of phosphorus forms in sediment, the addition of hydrochar promoted the transformation of unstable NH₄Cl-P, BD-P and Org-P into the very stable HCl-P in the sediment, which reduced the content of potential active phosphorus and also significantly reduced the content of biologically available phosphorus. This indicated that lanthanum-modified water treatment sludge hydrochar could effectively adsorb and remove phosphorus in water and could also be used as sediment improvement material to effectively stabilize endogenous phosphorus in sediment and control phosphorus content in water.