过氧化钙重塑底泥对水中磷酸盐的吸附作用

本研究模拟原位覆盖CaO₂流失后状态，以修复后表层2cm底泥为研究对象，通过扫描电子显微镜（SEM）和X射线能谱仪（EDX）对底泥修复前后表面进行观察和元素分析，发现CaO₂重塑明显改变了底泥结构，去除底泥表面附着的大部分有机物和铁锰氧化物，提高底泥颗粒孔隙率，增加底泥表面Ca²⁺含量；CaO₂重塑使底泥内源磷更加稳定，TP含量减少约20%，潜在活性磷含量减少约30%，Ca-P和Res-P含量明显增加，同时厌氧环境下重塑底泥磷释放量明显小于原始底泥，表明CaO₂重塑极大降低了底泥内源磷释放风险；Langmuir模型与Freundlich和Dubinin-Radushkevich模型相比，更适用于描述CaO₂重塑底泥对水中磷酸盐的等温吸附行为，CaO₂重塑明显提高底泥对水中磷酸盐的吸附能力，其最大磷吸附量由1.44 mg·g^-1增加到20.91 mg·g^-1，其对水中磷酸盐的吸附机制由化学吸附转变为物理化学吸附共同作用，此外准二级动力学模型可以较好地描述CaO₂重塑底泥对水中磷酸盐的吸附动力学过程，且CaO₂重塑显著提高底泥对水中的磷酸盐的吸附速率.

Adsorption Behavior of Phosphate by CaO2 Remolded Sediment

This study simulated the state of CaO₂ loss after in situ coverage and examined the bottom 2 cm of sediment after restoration. Observations and elemental analysis of the sediment using scanning electron microscopy (SEM) and X-ray energy spectrometry (EDX) were also performed. The CaO₂ remodeling notably changed the structure of the sediment; most of the organic matter and iron-manganese oxide attached to the sediment surface was removed, the porosity of the sediment particles increased, and the Ca²⁺ content was also increased. CaO₂ remodeling stabilized the endogenous phosphorus in the sediment; total phosphorous (TP) was reduced by approximately 20% and potential active phosphorus content was reduced by approximately 30%. Furthermore, the contents of Ca-P and Res-P were significantly increased. The amount of phosphorus released from the remodeled sediment under anaerobic conditions was significantly lower than the original sediment, indicating that the CaO₂ remodeling greatly reduced the risk of endogenous phosphorus release. The Langmuir model was more suitable than the Freundlich and Dubinin-Radushkevich models for describing the isothermal adsorption behavior of the CaO₂ remodeling, which significantly improved the adsorption capacity of the sediment with respect to phosphate from 1.44 mg·g^-1 to 20.91 mg·g^-1. The mechanism of adsorption was switched from chemical adsorption to physicochemical adsorption. In addition, the adsorption kinetics of the CaO₂ remodeled sediment with respect to phosphate could be best described using the quasi-second-order kinetic model.