3种Ca(OH)2改性材料对水体磷的吸附特征研究

Study on Phosphorus Adsorption Characteristics from Water by Three Kinds of Ca(OH)2 Modified Materials

采用Ca(OH)2对膨润土、红壤和炉渣进行改性,研究了改性材料对水体磷酸盐的吸附机理,探讨其脱附再生利用的可行性。结果表明,Ca(OH)2改性能够明显增加3种材料的Ca含量并改变其表面形貌特征,且显著增加了红壤的比表面积(P<0.05)。3种改性材料对磷的等温吸附曲线更符合Langmuir模型,单分子层和化学吸附的共同作用是主要除磷机制;改性膨润土、红壤和炉渣对磷的吸附是一个相对缓慢过程,分别在32、24、24 h达到吸附平衡,符合准2级动力学方程。通过4次吸附-解吸实验,3种材料的解吸率低于1%,Ca2+在材料表面形成了碳酸钙等沉淀物,影响吸附剂的可重复利用性。改性材料增加了对富营养化水体磷的去除能力,可为筛选强化人工湿地磷污染去除的基质材料提供理论依据。

Bentonite,red soil and slag was modified by Ca(OH)2,the phosphorus adsorption mechanism from water by modified materials were studied and the reuse feasibility was discussed.The results showed that,calcium content of the materials increased significantly and their surface morphology changed after Ca(OH)2 modification,the specific surface area of red soil significantly increased(P<0.05).The equilibrium adsorption data of phosphate from aqueous solution on the three modified materials could be better described by the Langmuir isotherm model,and the monolayer adsorption and chemical adsorption were the main phosphorus removal mechanism.The phosphate adsorption by modified bentonite,red soil and slag was a relatively slow process with adsorption equilibrium time of 32,24 and 24 h,respectively.The adsorption kinetics of phosphate was more suitable to be described by the pseudo-second-order kinetic equation.The phosphorus desorption rate of the three materials was lower than 1%through four adsorption-desorption cycles,which could be attributed to CaCO3 precipitate formation on the material surface,reducing the reusability of the adsorbents.The removal efficiency of phosphorus from eutrophic waters was enhanced by the modified materials,which provides a theoretical basis for screening substrate for strengthening phosphorus removal in constructed wetlands.